The EAPS Weekly News

November 10, 2014 Like EAPS on Facebook Follow EAPS on Twitter

UPCOMING EAPS MEETINGS

EAPS STAFF MEETINGS Thursday, Nov. 20, 2014

9:00-10:00 a.m. HAMP 2201

~ ~ ~ ~ ~ ~ EAPS RECEPTIONS AT CONFERENCES

AGU (SAN FRANCISCO) Wednesday, Dec. 17, 2014

7:00 - 9:00 p.m. Thirsty Bear-Billar Room

AMS (PHOENIX) Tuesday, Jan. 6, 2015

6:30 - 8:30 p.m. Sheraton Phoenix Downtown Hotel

~ ~ ~ ~ ~ ~ FALL FACULTY MEETING SCHEDULE

Tuesday, Nov. 18, 2014 3:00-4:30 p.m. HAMP 3201

SPRING FACULTY MEETING SCHEDULE

Tuesday, Jan. 27th, Feb. 10th (Dean’s Visit to Dept.), Mar. 24th, and Apr. 14th, 2015

3:00-4:30 p.m. HAMP 3201

PUBLICATIONS

Qin, Zhangcai and Zhuang, Qianlai (2014) Estimating Water Use Efficiency in Bioenergy Ecosystems Using a Process-Based Model, in Remote Sensing of the Terrestrial Water Cycle (eds V. Lakshmi, D. Alsdorf, M. Anderson, S. Biancamaria, M. Cosh, J. Entin, G. Huffman,W. Kustas, P. van Oevelen, T. Painter, J. Parajka, M. Rodell and C. Rüdiger), John Wiley & Sons, Inc, Hoboken, NJ. doi:10.1002/9781118872086.ch30

EAPS COLLOQUIA

“Profiling Developing Tropical Storm Environments Using GPS Airborne Radio Occultation”

Brian Murphy PhD Candidate

Tuesday, Nov. 11, 2014 at 4:00 p.m. HAMP 2201

“Opportunities and Challenges of Shale Gas Development” Mark D. Zoback

Thursday, Nov. 13, 2014 at 4:00 p.m. Matthews Hall/Room 210 Please see attached map.

(Please see attached fall 2014 EAPS Colloquia)

EAPS NEWS

ELEMENTS MAGAZINE

The most recent issue of Elements magazine is devoted to cosmogenic nuclides; an area in which EAPS and Purdue have become a world leader. Two out of six articles in this feature are authored by our own Nat Lifton and Darryl

Granger. It is an honor for our department and our faculty to be featured so prominently in such a high profile journal read by earth scientists who want to know about what

people in other fields are doing. We are very proud of efforts made by both Nat and Darryl as well as PRIME lab and

Marc Caffee to make it possible. Please see attached.

http://www.facebook.com/EAPSPurduehttp://www.twitter.com/PurdueEAPS

~ --

EAPS OMBUDSMAN

What is an Ombudsman? The ombudsmen are an informal, neutral, confidential resource for people in the department, especially students, to raise questions or concerns about any aspect of their academic experience. The EAPS ombudsman is Barbara Gibson (HAMP 2169B;

barbara@purdue.edu) - please feel free to contact her if needed.

UNDERGRADUATE AND GRADUATE STUDENT INFORMATION

OPENHATCH

On Sunday, Nov. 16th, OpenHatch and Purdue’s Computer Science Women’s Network are hosting a day-long (12:30 - 6:30) open source software immersion event. We invite Earth, Atmospheric, and Planetary Science students to join us! You can sign up here: http://purdue.openhatch.org/. You don’t need to be a programmer to contribute to open

source, or to attend and enjoy our event. Most open source projects are also in need of designers, translators, documenters, bug-finders and testers. The event is open to all students. Open source software -- software that is shared freely and

available to build upon -- has become part of our daily lives. Popular projects like WordPress, Firefox, Adium, and Ubuntu have millions of users. In the atmospheric sciences, agencies like the EPA and the National Weather Service lead development of open source projects like GEMPAK, a weather forecasting, display and analysis software package, and CMAQ, a program for air quality modeling, not to mention the dozens of other projects in academia and industry. You can learn more about these projects, and start helping out with them, at our event. Open source participation is one way to gain real-world

skills and make connections that will last you through your career. Volunteer staff will include professionals and academics that use open source daily.

~ ~ ~ ~ ~ ~ BENDER VIRTUAL CAREER FAIR – EMPLOYMENT FOR

PEOPLE WITH DISABILITIES

Thursday, November 13, 2014. Students and alumni with disabilities are invited to chat with employers. Register at www.careereco.com/register/disability.

TALENTED WRITERS

The Writing Lab is looking for talented undergraduate writers of all majors who demonstrate a strong interest in business, technical, or professional writing to join us as Business & Professional Writing Consultants. Prospective consultants will enroll in a Spring 2015 training course which will prepare them to work with students on a variety of workplace documents and course assignments, including resumes, cover letters, memos, and reports.

o Undergraduates of all majors are invited to apply for spring 2015;

o Prerequisite courses include one of ENGL 203, 306, 309, 420, 421, or 422;

o Applications must include a recommendationfrom a former English instructor as well as acurrent résumé and cover letter.

~ ~ ~ ~ ~ ~ PETROLEUM AND GEOSYSTEMS ENGINEERING

INTERNSHIPS

Summer research internships are available for undergraduate students within the UT Austin Petroleum and Geosystems Engineering Department. UT PGE is currently accepting applications for interns, where they will work for 10 weeks in the summer of 2015 for a salary of $4000 plus on-campus housing, a meal plan and travel to Austin. The interns will be mentored by a UT PGE faculty member and work on a project that is of interest to them. This is a great opportunity for an undergraduate to get research experience, learn about the energy industry and a taste of the grad school experience. SURI will consider application students from all engineering and science majors with at least a 3.25 GPA. This program only accepts students who are U.S. Citizens or permanent residents. The deadline to apply is January 12, 2015. Apply to PGE.

~ ~ ~ ~ ~ ~ TAIWAN SPRING BREAK TRIP

Krannert is opening spaces for the Taiwan Spring Break program, Asian Emerging Markets and Economies, to all Purdue majors at this time. During the program, students get to heavily interact with students from National Chengchi University, while learning about Asian economy and culture from the top professors and business executives in Taipei. Students receive 1 credit for the program and almost all costs are included in the program price. Information: Program applications will be open until Saturday, November 15th and we would love to have students from multiple disciplines at Purdue participate in the program.

http://purdue.openhatch.org/https://www.careereco.com/register/disabilityhttp://www.pge.utexas.edu/http://www.krannert.purdue.edu/undergraduate/study-abroad/short-term-programs/taiwan/home.aspmailto:barbara@purdue.edu

INTERN IN SINGAPORE SUMMER 2015

The companies include Rockwell Automation, Toshiba, Paypal, Rolls Royce, Hershey and several others. The program is open to all majors at Purdue and runs during the month of June. The call-out is Wed, Nov. 12th at 6 p.m. in HAAS Rm. G-066.

~ ~ ~ ~ ~ ~ PURDUE WINTERIZATION 2014

Interested in spending a day helping your community and having fun with your friends? Winterization is a community service project in which students from Purdue University assist in preparing the yards and homes of the elderly and disabled in Tippecanoe County for winter. This event will take place Saturday, November 15, 2014. Breakfast and lunch are provided for volunteers. For more information and to register please visit here.

~ ~ ~ ~ ~ ~ LBC CERTIFICATE

Interested in a certificate for Learning Beyond the Classroom? Visit LBC to find out more.

~ ~ ~ ~ ~ ~ NASA EARTH AND SPACE SCIENCE FELLOWSHIP

(NESSF) PROGRAM

NASA announces a call for graduate fellowship proposals to the NASA Earth and Space Science Fellowship (NESSF) program for the 2015-2016 academic years. This call for fellowship proposals solicits applications from accredited U.S. universities on behalf of individuals pursuing Master of Science (M.Sc.) or Doctoral (Ph.D.) degrees in Earth and space sciences, or related disciplines. The purpose of NESSF is to ensure continued training of a highly qualified workforce in disciplines needed to achieve NASA’s scientific goals. Awards resulting from the competitive selection will be made in the form of training grants to the respective universities. The deadline for NEW applications is February 2, 2015,

and the deadline for RENEWAL applications is March 16, 2015. The NESSF call for proposals and submission instructions

are located at the NESSF 15 solicitation index page at http://nspires.nasaprs.com/ - click on "Solicitations" then click on "Open Solicitations" then select the "NESSF 15" announcement. Also refer to “Proposal Submission Instructions” and “Frequently Asked Questions” listed under “Other Documents” on the NESSF 15 solicitation index page. All proposals must be submitted in electronic format only

through the NASA NSPIRES system. The advisor has an active role in the submission of the fellowship proposal. To use the NSPIRES system, the advisor, the student, and the university must all register. Extended instructions on how to submit an electronic proposal package are posted on the NESSF 15 solicitation index page listed above. You can register in NSPIRES at http://nspires.nasaprs.com/.

For further information contact Claire Macaulay, Program Administrator for NESSF Earth Science Research, Telephone: (202) 358-0151, E-mail: claire.i.macaulay@nasa.gov or Dolores Holland, Program Administrator for NESSF Heliophysics Research, Planetary Science Research, and Astrophysics Research, Telephone: (202) 358-0734, E-mail: hq-nessf-Space@nasa.gov.

~ ~ ~ ~ ~ ~ DINING ETIQUETTE WITH MR. ANTHONY CAWDRON

Purdue students are invited to a Professional Dining Etiquette Event with Mr. Anthony Cawdron in the Union's

west faculty lounge November 10th from 6-7p.m. The event is presented by Purdue CCO, Alpha Kappa Psi and Beta Alpha Psi and sponsored by ArcelorMittal. Mr. Anthony Cawdron is a dining etiquette expert and coordinator of Westwood (President Daniel’s residence). Students can reserve a seat for the presentation any time before the

event (11/10) using this link. View the Facebook event page here .

OTHER NEWS

CLIMATE CHANGE DIRECT HIRE AUTHORITY INTERNSHIP OPPORTUNITIES IN THE NATIONAL PARK

SERVICE PARTNERS

National parks and NPS programs develop and oversee structured projects in one or more of the following interdisciplinary areas: climate change science and monitoring; resource conservation and adaptation; policy development; sustainable park operations; facilities adaptation; and communication/interpretation/education. During the internship, students apply critical thinking and problem solving skills to climate change challenges and communicate with diverse stakeholders. Interns who successfully complete the YLCC, an approved Direct Hire Authority Internship program, will be eligible to be hired non-competitively into subsequent federal jobs once they complete their degree program. These jobs would be in the Department of Interior (DOI), NPS, or one of the other bureaus within the DOI. An intern must qualify for the job in order to be hired non-competitively.

Quick Facts and Deadlines: • The YLCC is managed cooperatively with the University of Washington • Internship opportunities and application forms are posted on parksclimateinterns.org • Internships are 11-12 weeks (40 hours/week) during the summer • Interns are paid $14/hour plus benefits • Applications are accepted from early December 2014 until late January 2015

This is a great opportunity for students who might be interested in a climate change internship. Upon completion, students will be eligible to be hired non-competitively into subsequent federal positions once they have completed

http://www.purduewinterization.org/http://science.purdue.edu/Current_Students/learning-beyond-the-classroom/enroll.htmlhttps://urldefense.proofpoint.com/v2/url?u=http-3A__nspires.nasaprs.com_&d=AAMFAg&c=jF7FvYH6t0RX1HrEjVCgHQ&r=p_kmtdKbcxzYOYWhwJpYmQ&m=7gc_mSHXX3ASgm2wSsktbSJmWTGeyM_DPGk61Q1odPo&s=72e9nk9xl3F2bLn_IKmGsqSnskOqqALEls7_VJM2WeA&ehttps://urldefense.proofpoint.com/v2/url?u=http-3A__nspires.nasaprs.com_&d=AAMFAg&c=jF7FvYH6t0RX1HrEjVCgHQ&r=p_kmtdKbcxzYOYWhwJpYmQ&m=7gc_mSHXX3ASgm2wSsktbSJmWTGeyM_DPGk61Q1odPo&s=72e9nk9xl3F2bLn_IKmGsqSnskOqqALEls7_VJM2WeA&emailto:claire.i.macaulay@nasa.govmailto:hq-nessf-Space@nasa.govhttp://goo.gl/zbZICbhttps://www.facebook.com/events/1560809187483840/?notif_t=plan_editedhttp:parksclimateinterns.org

their degree programs. Application deadline is January 30, 2015. For More Information contact Tim Watkins, Climate

Change Response Program, NPS, TimWatkins@nps.gov

~ ~ ~ ~ ~ ~ INDIANA STATE DEPARTMENT OF HEALTH

October 29, 2014

The first cases of Ebola Virus Disease (EVD) diagnosed in the United States have heightened awareness of our global community and this serious disease. It also raised the level of concern for the safety of travelers both to the affected counh·ies, and those returning to Indiana from an affected country, and the safety of the academic community. The Ebola virus is not spread through the air, by water or

food, or by casual contact. People with Ebola can only spread the Ebola virus when they have symptoms. There is no lmown risk of transmission if someone does not have symptoms. Ebola is only spread through direct contact with blood or body fluids (including but not limited to urine, saliva, feces, vomit and semen, or a needlestick) of a person who is sick with Ebola or the body of a person who has died from Ebola. Currently in the U.S., individuals at risk for developing

EVD are those who have arrived in the U.S. from Guinea, Liberia, or Sierra Leone within the past 21 days (the maximum incubation period for Ebola virus). Previous travel to these countries outside the 21-day incubation period is not a risk factor for Ebola. Individuals who have had direct contact with identified

Ebola cases in the U.S. may also be at risk for the EVD if that contact occurred at the time the case was symptomatic. Ebola symptoms include fever, headache, nausea, vomiting, diaIThea, muscle or body aches, and fatigue. The Indiana State Department of Health (ISDH) website has more information about EVD at www.statehealth .in.gov. The Centers for Disease Control and Prevention (CDC)

has prepared a document specifically addressing the unique concerns of colleges, universities, and students around the EVD occurring in the West African countries of Guinea, Liberia, and Sierra Leone. You can find that information at: http://wwwnc.cdc .gov/travel/page/advice-for-college s-universities-and-student s-about-ebola-in -west-africa. To read more, please see attached.

APPLICATIONS SOUGHT FOR NEXT IMPACT COHORT November 3, 2014

The IMPACT program is now taking applications for the spring 2015 cohort, and applications are due by 5 p.m., Nov. 28th. The application link and information about the program are available at www.purdue.edu/impact.

IMPACT (Instruction Matters: Purdue Academic Course Transformation) is a campus-wide initiative begun in 2011 by the Provost's Office for the redesign of classes. Its aim is to engage students more fully in their learning, thereby improving competency, retention and completion in classes that serve students across the entire campus. It is related to Purdue Moves and the University's efforts to be the national forerunner in transformative higher education.

For more information on the program, contact Chantal Levesque-Bristol, director of the Center for Instructional Excellence, at cbristol@purdue.ed

BIRTHDAYS

Nov. 10th

Nov. 11th Tim Filley Frank Bakhit

Nov. 12th Gerald Krockover Nov. 12th Ken Ridgway

mailto:TimWatkins@nps.govhttp://wwwnc.cdc/http://www.purdue.edu/impacthttp://www.purdue.edu/purduemoves/mailto:cbristol@purdue.edwww.statehealth

What- people t-h1nk a6ou-t during ~our c..onterenc..e t-aH-.o(,

1-k':j! -n...t•

Profiling Developing Tropical Storm Environments Using GPS Airborne Radio Occultation

An extensive set of airborne radio occultation (ARO) data has been collected by GISMOS, the GNSS Instrument System for Multi-static and Occultation Sensing, while deployed during the PRE-Depression Investigation of Cloud systems in the Tropics (PREDICT) experiment in 2010 to study developing tropical storms in the southern Atlantic and Caribbean region. This is the first time RO observations have been used to investigate the spatial and vertical variability of moisture with sufficient density (~ 7 profiles within 450 km of the storm center ) to characterize the mesoscale storm environment. GISMOS applies the radio occultation technique to remotely sense the atmosphere by measuring the phase delay and amplitude of received GPS radio signals due to the density and water vapor content of the atmosphere. High resolution vertical profiles of atmospheric refractivity below the aircraft altitude are obtained from the ARO data. Both geodetic GPS receivers using conventional phase-lock loop tracking and a high rate 10 MHz GPS recording system were used to collect GPS signal data over twenty-six missions. The ARO profiles retrieved from the geodetic receivers consistently agree within ~2 % of refractivity profiles calculated from the European Center for Medium-range Weather Forecasting (ECMWF) model interim re-analyses as well as from nearby dropsondes and radiosondes. The number of profiles and the minimum altitude sampled by the profiles obtained from the geodetic receivers were limited by the conventional phase-lock loop tracking which does not perform optimally in the lower tropical atmosphere where moisture levels result in sharp changes in refractivity causing rapid changes in GPS signal phase. A much larger set of profiles extending farther below aircraft height is obtained from the 10 MHz recorded GPS signal data using an open loop tracking algorithm, which is implemented in a software receiver. We will demonstrate the consistency of the combined dropsonde and RO dataset with increasing moisture in the mid-to-upper tropopause over the hurricane genesis time period for Karl.

Purdue University Joint Earth, Atmospheric, and Planetary Sciences /

Physics and Astronomy Colloquia S. Thomas Crough Memorial Lecture

Mark D. Zoback Prof. of Geophysics, Stanford University

Opportunities and Challenges of Shale Gas Development Thursday, November 13 4:00 PM – 5:00 PM Mathews Hall Room 210 Refreshments at 3:30 in Mathews 210

Open to the public

Abstract: The proven ability to produce large quantities of natural gas from organic-rich shale formations is changing the energy picture in many parts of the world. In this talk I will discuss steps that can be taken to assure such resources are developed in an optimally efficient and environmentally responsible manner. Responsible development of shale gas resources has the potential to substantially reduce greenhouse gas emissions in the near term and significantly reduce air pollution and benefit public health. I will discuss several on-going research projects investigating the wide variety of factors affecting the successful gas production from these extremely low permeability formations and procedures for managing the risks of earthquakes triggered by injection of hydraulic fracturing waste water.

Dr. Mark D. Zoback is the Benjamin M. Page Professor of Geophysics at Stanford University. Dr. Zoback conducts research on in situ stress, fault mechanics, and reservoir geomechanics with an emphasis on shale gas, tight gas and tight oil production. Dr. Zoback was one of the principal investigators of the SAFOD project in which a scientific research well was successfully drilled through the San Andreas Fault. He is the author of a textbook entitled Reservoir Geomechanics published in 2007 by Cambridge University Press, the author/co-author of 300 technical papers and holder of five patents. Dr. Zoback has received numerous awards and honors, including the 2006 Emil Wiechert Medal of the German Geophysical Society and the 2008 Walter H. Bucher Medal of the American Geophysical Union. In 2011, he was elected to the U.S. National Academy of Engineering and in 2012 elected to Honorary Membership in the Society of Exploration Geophysicists. He recently served on the National Academy of Engineering committee investigating the Deepwater Horizon accident and the Secretary of Energy’s committee on shale gas development and environmental protection.

[Type text]

PURDUE UNIVERSITY Department of Earth, Atmospheric, and Planetary Sciences

Colloquia – Fall 2014Thursdays at 3:30 PM, Room 1252 HAMP (unless noted)

Sept. 4 When Engineering Geology Meets Geotechnical Engineering

Sept. 9

Gary Luce, Knight Piesold & Co., AEG President

The Impact of Climate Change and Agricultural Activities on Water

Host: West

Cycling in Northern Eurasia Yaling Liu, PhD Candidate Advisor: Zhuang

Tuesday, 4:00PM, Room 2201/HAMP

Sept. 11 The DOE Accelerated Climate Modeling for Energy Project Dr. Robert Jacob, Argonne National Laboratory Host: Harshvardhan

Sept. 18 The Origins of Volatile-rich Solids and Organics in the Outer Solar Nebula Prof. Fred Ciesla, University of Chicago Host: Minton

Sept. 25 Long-term Morphological Changes in Mature Supercell Thunderstorms Following Merger with Nascent Supercells

Prof. Ryan Hastings, Purdue University Sept. 30 Making Weather and Climate Data More Usable for Agriculture Across

the U.S. Corn Belt Olivia Kellner, PhD Candidate Advisor: Niyogi

Tuesday, 4:00PM, Room 2201/HAMP

Oct. 2 New Perspectives on Tidewater Glacier Mass Change Dr. Tim Bartholomaus, University of Texas-Austin Host: Elliott

Oct. 9 Sulfur Cycling on Mars from a Perspective of Sulfur-Rich Terrestrial Analogs Prof. Anna Szynkiewicz, University of Tennessee Host: Horgan

Oct. 16 Climate Impacts and Extremes in Large Earth System Model Ensembles Prof. Ryan Sriver, University of Illinois-Champaign/Urbana Host: Wu

Oct. 21 Towards a Paradigm Shift in the Modeling of Soil Carbon Decomposition for Earth System Models

Yujie He, PhD Candidate Advisor: Zhuang Tuesday, 4:00PM, Room 2201/HAMP

Oct. 23 Anthropogenic Signals in InSAR Prof. Rowena Lohman, Cornell University Host: Elliott/Flesch

Oct. 28 Giant Impacts on the Asteroid Vesta Tim Bowling, PhD Candidate Advisor: Melosh

Tuesday, 4:00PM, Room 2201/HAMP

Oct. 30 Abiotic and Biogeochemical Controls on Reactive Nitrogen Cycling on Boundary Layer Surfaces

Prof. Jonathan Raff, Indiana University Host: Shepson

(continued on next page)

PURDUE UNIVERSITY Department of Earth, Atmospheric, and Planetary Sciences

Colloquia – Fall 2014 (cont.)

Nov. 6 Andean Foreland Basins: A Thermochronologic Perspective on Sediment Provenance, Deformation, and Basin Thermal Histories

Prof. Julie Fosdick, Indiana University Host: Ridgway

Nov. 11 Profiling Developing Tropical Storm Environments Using GPS Airborne Radio Occultation

Brian Murphy, PhD Candidate Advisor: Sun/Haase Tuesday, 4:00PM, Room 2201/HAMP

Nov. 13 Shale Gas Development and the Environment Prof. Mark Zoback, Stanford University Host: Nowack

Thursday, 4:00pm, Room 210/MTHW (joint with the Physics Dept.)

Nov. 20 The Role of Monsoon Circulation on Tropopause Variability Prof. Yutian Wu, Purdue University

Dec. 4 CSI Patagonia: Tracking Glacial and Climate Dynamics over the Last Glacial Cycle Alessa Geiger, University of Glasgow Host: Harbor

[Type text]

The Nuts and Bolts of Cosmogenic Nuclide Production

Tibor J. Dunai1 and Nathaniel A. Lifton2

Supernova explosions, such as the one that

formed the Crab Nebula, are the major source

of cosmic rays. CREDIT: NASA/ESA / J. HESTER

1811-5209/14/0010-347$2.50 DOI: 10.2113/gselements.10.5.347 (ARIZONA STATE UNIVERSITY), STSCI-2005-37

O ver the last 60 years, our understanding of how cosmic rays produce cosmogenic nuclides has grown from basic physical considerations. We introduce the different types of cosmic ray particles and how their COSMIC RAY PARTICLES flux varies with altitude, latitude, and time. Accurately describing these varia-

tions remains a challenge for some regions when calculating production rates. At t he top of t he E a r t h’s atmosphere, galactic cosmic rays We describe current and emerging computational methods for calculating are dominated by protons (87%)

production rates that address this challenge. Continuing developments in and α-particles (12%), with a small our understanding of modern and prehistoric cosmic ray fluxes and energy contribution of heavier nuclei

(~1%). Upon entering the Earth’s spectra in Earth’s atmosphere and at its surface are bound to contribute in atmosphere, these primary cosmic

the future to more robust applications. rays interact with the atoms in the air to produce secondary cosmic KEYWORDS: cosmogenic nuclide production, reaction, scaling factor, cosmic ray rays. Some of these secondary particles (neutrons and muons) are responsible for most of the atmospheric and in situ cosmo-genic nuclides on Earth. INTRODUCTION

Cosmic rays are high-energy charged particles that impinge on the Earth from all directions from space. The majority of cosmic ray particles are atomic nuclei, but they also include electrons, positrons, and other subatomic particles. Typical energy levels range from a few mega–electron volts (MeV) up to ~1020 eV, with a maximum energy of a few hundred MeV per nucleon (Eidelman et al. 2004).

For the purposes of in situ and atmospheric cosmogenic nuclides, the term cosmic rays usually refers to galactic cosmic rays, which originate from sources outside the Solar System. Supernova explosions, which occur approximately once every 50 years in our galaxy, produce most galactic cosmic rays, with energies of up to 1015 eV (Eidelman et al. 2004; Diehl et al. 2006). The galactic cosmic ray flux is generally assumed to be isotropic and to have been approxi-mately constant over the last 10 million years (Leya et al. 2000). Good entry-level reviews on cosmic ray physics can be found, for example, in Rossi (1964) and in reviews on geologic applications of cosmogenic nuclides (Gosse and Phillips 2001; Dunai 2010). In the following section, we draw from these sources, and their references, to introduce the nature of cosmic ray particles and the mechanisms of cosmogenic nuclide production.

Nucleons The high energies of the primary (and many secondary) cosmic rays are well in excess of the binding energies of atomic nuclei (typically 7–9 MeV per nucleon). Consequently, the dominant nuclear reaction is that of spallation, the process by which nucleons are sputtered off target nuclei. Spallation-produced nucleons largely continue in the direction of the impacting particle and can retain enough energy to keep on inducing spallation in other target nuclides, producing a nuclear cascade in the Earth’s atmosphere (FIG. 1).

Because neutrons do not lose energy through ionization as do protons, the composition of cosmic rays undergoes changes from proton-dominated to neutron-dominated over the course of the nuclear cascade. At sea level, neutrons constitute 98% of the nucleonic cosmic ray flux. However, energy losses incurred with each interaction result in the mean energy of the secondary neutron flux being signifi-cantly lower than that of the primary flux (FIG. 1).

Muons In addition to producing secondary atmospheric neutrons, collisions of high-energy primary cosmic rays with atomic nuclei high in the atmosphere produce elemental particles known as pions, which decay within a few meters of travel to either positively or negatively charged muons. Muons can be considered the heavier brother of the electron (206.7 times heavier).

Muons interact only weakly with matter—therefore, they have a much greater penetration depth than nucleons, and hence are the most abundant cosmic ray particles at sea level. However, due to stronger interaction with matter, the

1 Institute for Geology and Mineralogy, University of Cologne Zülpicher Str. 49b, 50674 Köln, Germany E-mail: tdunai@uni-koeln.de

2 Departments of Earth, Atmospheric, and Planetary Sciences, and Physics and Astronomy, Purdue University 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, USA E-mail: nlifton@purdue.edu

ELEMENT S, VOL . 10, PP. 347–350 347 OCT OBE R 2014

mailto:tdunai@uni-koeln.demailto:nlifton@purdue.eduhttp:1811-5209/14/0010-347$2.50

I I I I I I I I

I

I

I

a. I

I

I

I

I

I

I

I

I n µ I

I l I I I I I I I I I I I

a. I

__ .. __ I

I

I

I

I

I I

t I I I I

( )'( )'

-

nucleonic component dominates atmospheric and terres-trial cosmogenic nuclide production. Muons, in turn, are responsible for the majority of subsurface production.

COSMOGENIC NUCLIDES Cosmogenic nuclides are the products of interactions of primary and secondary cosmic ray particles with atomic nuclei. At the Earth’s surface, more than 98% of the cosmo-genic nuclide production arises from secondary cosmic ray particles, such as neutrons and muons. Depending on the energy of these particles, a range of nuclear reactions can produce cosmogenic nuclides (FIG. 1).

Spallation In spallation reactions, high-energy nucleons (largely neutrons at ground level) collide with atomic nuclei (“target nuclei”) and knock off protons and neutrons, leaving behind a lighter residual nucleus. The mass differ-ence between a target nucleus and the lighter product is usually a few atomic mass units. Thus, target elements with nuclide masses nearest to the resulting cosmogenic nuclide usually contribute most to its production.

Neutron Capture The majority of neutrons in the nuclear cascade eventually slow down to energies corresponding to the temperature of their surroundings. These “thermal” neutrons (energies of ca 0.025 eV) can subsequently be captured by nuclei. Some thermal neutron–capture reactions have very high probabilities of occurrence and can produce appreciable amounts of cosmogenic nuclides (e.g. 3He, 36Cl).

THE ATMOSPHERIC NUCLEAR CASCADE

softening of energy spectrum

increasing atmospheric depth / atm. pressure

+

N

P, N: high-energy (>10 MeV) secondary protons and neutrons carrying the nuclear cascade

n, p, : secondary particles not carrying the nuclear cascade

± , ±, e±: pions, muons, electrons, and positrons

primarycosmic ray particle

target nucleus (e.g. N, O, Ar)

P N

n p P p

N n p n P

e -

e N p p

e± n p

n N n

residual nuclei are “cosmogenic nuclei” N n

n p

electromagnetic mesonic nucleonic

Nuclear reactions in the atmosphere produce atmospheric cosmogenic nuclides as well as secondary

FIGURE 1

particles, mostly neutrons. The latter are responsible for the cosmo-genic nuclides measured in minerals. FIGURE REDRAWN AFTER DUNAI (2010)

Muon Reactions There are two main types of muon reactions leading to cosmogenic nuclide production: negative muon capture and high-energy (fast) muon interactions. Negative muons that have been decelerated by ionization to thermal energies (termed “stopped muons”) can be captured by an atom’s electron cloud, and they quickly cascade to the lowest electron shell. There they decay, or are captured by the nucleus where they neutralize one proton. The probabilities for negative muon–capture reactions are much lower than those involving neutrons.

Fast muons give rise to Bremstrahlung (“braking radia-tion”), which produces gamma ray photons. This phenom-enon occurs when charged particles slow down due to interactions with other charged particles. Such muon-derived gamma rays can be of sufficiently high energy to produce secondary neutrons from nuclei, the so-called photoneutrons, which may produce cosmogenic nuclides. They generally have a very low abundance and become important only at depths greater than 20 m below the Earth’s surface, where fast muons remain as the sole reaction-inducing “survivors” of the cosmogenic cascade.

PRODUCTION RATES AND SCALING FACTORS The production rates of cosmogenic nuclides are a function of the energy spectrum of the impacting cosmic ray particles and the corresponding reaction probabilities for target nuclei (Reedy 2013). The energy spectrum itself is a function of altitude and position in the geomagnetic field. As discussed in von Blanckenburg and Willenbring (2014 this issue), nuclide production occurs both in atmospheric gases (“atmospheric”) and in the minerals of the upper several meters of the Earth’s surface (“in situ”). In the atmosphere, nuclide production rates are typically estimated from theoretical and/or numerical models (e.g. Masarik and Beer 1999), while nuclide delivery is computed from atmospheric circulation models (Heikkilä et al. 2013). In contrast, terrestrial production rates of in situ cosmo-genic nuclides are typically experimentally established at sites that have independently determined ages (e.g. moraines, lava flows) and well-constrained exposure histo-ries (i.e. no significant prior exposure, erosion, burial, or other disturbance that can impact the cosmogenic nuclide inventory in the rock since initial exposure) (Gosse and Phillips 2001; Dunai 2010).

Identifying suitable calibration sites for terrestrial produc-tion rates requires careful characterization, and the number and geographic distribution of these sites remain limited. Scaling factors are required to translate the local production rates obtained at calibration sites to values valid elsewhere on the globe, where practitioners may use cosmogenic nuclides to obtain exposure ages and rates of geological processes. Again, this is because the cosmic ray energy spectrum varies spatially. Scaling factors must also account for temporal variations in geomagnetic and atmospheric shielding at a given location that can affect the cosmic ray flux and its energy spectrum (FIG. 2).

Geomagnetic and Atmospheric Shielding Primary cosmic rays are charged particles and are thus affected by Earth’s magnetic field. At a given location, particles with kinetic energy below a certain threshold cannot penetrate the Earth’s magnetic field and approach the Earth’s surface. This threshold is referred to as the “cutoff rigidity,” or RC, and is defined as the momentum of a particle per unit charge (in gigavolts, GV).

ELEMENT S 348 OCT OBE R 2014

• ....~ ["loo .... ' ~

~, .... '~ .... I"'- """' ...... I'-,, ~ ~ ~ ....

... I'-,, ~ .... .:::' '"" ~ .... -- ....... - ..... .... , .... , .... , .... , .... , .... , .... , .... , .... , ... , .... .... , .... , .... ....

• • I

I • . • I .. I -· .. ... ... I .. ..

r-./ ... - ... ~ ..... - - ----I I I .,

-

-

A

B

Scaling Factor

A 1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

Sea Level

LSD Lal (1991)/Stone (2000) Desilets and Zreda (2003)

Secondary neutrons produced in the atmospheric nuclear cascade attain a maximum flux at an altitude of about 16 km (Lal and Peters 1967). Below that level, their abundance decreases approximately exponentially with atmospheric depth, which is described by the attenuation length (FIG. 2B). As a rule of thumb, the nucleonic cosmic ray flux decreases by half for every 1000 m decrease in altitude (Dunai 2010).

Systematic changes in the secondary cosmic ray spectrum as a function of atmospheric depth and RC lead to corre-sponding variations in attenuation lengths (Lifton et al. 2014). Current scaling models account for this variation by directly varying attenuation lengths (Dunai 2001;

0 2 4 6 8 10 12 14 16 18 20 Desilets and Zreda 2003) or by parameterizing altitudinal [90] [52] [43] [36] [30] [24] [17] [6] and latitudinal variation in other ways (Lal 1991; Lifton

et al. 2014). RC (GV) [Geomagnetic Latitude (°N)] It is worth noting that while meteoric cosmogenic nuclides,

such as 10Be, are also produced in the atmosphere largely by spallation reactions, applications of such meteoric 10Be

B 140 are instead concerned with fluxes of the nuclide from the

Scaling Factor

10

8

6

4

2

0 1,050 950 850 750

Atmospheric Depth (g cm-2) 0 GV 15 GV

total inventory in the atmospheric column above a given site (Willenbring and von Blanckenburg 2010). It is signifi-cant that >99% of the atmospheric inventory is produced above 3 km altitude—thus, no altitude scaling is required for most of Earth’s surface. Rather, the 10Be production signal is dominated by the high cosmic ray fluxes in low RC regions (Willenbring and von Blanckenburg 2010).

Once produced, meteoric 10Be quickly adsorbs to aerosol particles that are transported by atmospheric circulation and

120

Scaling Factor

100

80

60

40

20

0 1,050 950 850 750 650 550 450 350

[700] [1620] [2620] [3750] [5000] [6500] [8250]

Atmospheric Depth (g cm-2) [Altitude (m)]

delivered to the Earth’s surface by either dry or wet deposi-tion. Combination of 10Be production and atmospheric general circulation models indicates that 10Be fluxes are dominated by wet deposition—therefore, mid-latitudes that experience high precipitation also experience the highest fluxes (Willenbring and von Blanckenburg 2010; Heikkilä et al. 2013). Comparison of (A) latitude scaling factors at sea level

and (B) altitude scaling for two cutoff rigidities (RC). FIGURE 2

(A) Scaling model of Lifton et al. (2014) as a representation of the atmospheric nucleon flux (abbreviated as LSD). Earlier scaling models based on nuclear disintegrations and various neutron detec-tors (Lal 1991, reparameterized by Stone 2000; and Desilets and Zreda 2003) are presented for comparison. The large discrepancy 200.90

0.70

RC

SFinstantaneous

SF10 integrated

SF14 integrated

12

at sea level between Lal (1991) and LSD is due to different geomag-0.85 18netic parameterization in the former. (B) Altitudinal scaling for the

LSD model at low and high RC values. The differences between the two curves arise from two effects: sea level variation in the nucleon flux as a function of RC, and variation in the attenuation length of the nucleon flux as a function of both RC and atmospheric depth (Lifton et al. 2014). Inset shows scaling in the lower 2600 m of the atmosphere.

Modern RC values are approximately zero near the poles, where essentially all energies present in the primary flux can penetrate the magnetic field. This value increases to

0.80 16

Scaling Factor

0.75 14

RC (GV)

0.65 10 0.60 8 0.55 6 0.50 4

approximately 17 GV near the equator (ca 50 % of the 0.45 2polar flux at sea level) (FIG. 2A). At RC < 1–2 GV (≥ ca 60°

geomagnetic latitude), the lowest-energy particles do not 0.40 0 have enough energy to generate an atmospheric cascade, 0 25 50 75 100 125 150 and so toward the poles the increases in the number of Age (ka) particles that enter the atmosphere do not yield corre-

FIGURE 3 The time variations in atmospheric nucleon flux (LSD) scaling factors for sea level and an equatorial location

sponding increases in the flux responsible for cosmogenic nuclide production.

are predicted using the geomagnetic field record employed in The cosmic ray spectrum at high latitudes is not sensitive to temporal changes in the geomagnetic field. Hence, terres-trial production rates are usually normalized to hypothet-ical values at sea level and high latitudes. However, the effects of secular geomagnetic field variations on nuclide production become more pronounced with increasing RC (at lower latitudes) and need to be considered when calcu-lating nuclide production in the past (Dunai 2001; Desilets and Zreda 2003; Lifton et al. 2008; FIG. 3).

Lifton et al. (2014). Note the inverse covariation of the instanta-neous variations of the relative cosmic ray flux and the cutoff rigidity (RC) at the high RC location. The integrated cosmic ray flux (i.e. the time-averaged scaling factor applicable to a given age), as relevant for exposure dating utilizing in situ cosmogenic nuclides, is shown for 10Be and 14C. Due to the integrated nature, the high-amplitude variations are dampened with increasing exposure time. For long exposure, integrated production rates of 10Be and 14C differ according to their half-lives. No variations would be observed in either time-varying RC or flux intensity at low RC locations, e.g. at >60° geomagnetic latitude. SF = scaling factor; ka = thousand years.

ELEMENT S 349 OCT OBE R 2014

Scaling Factors for In Situ neutron energy spectra and the lack of accurate neutron reaction probability functions; both have become recently Cosmogenic Nuclide Production available (Sato et al. 2008 and references therein; Reedy

Computationally complex calculations are required to 2013). These new studies (Argento et al. 2013; Lifton et consider the effects of spatial and temporal variations in al. 2014) indicate that nuclide-specific scaling factors may the geomagnetic field and atmospheric pressure on scaling be warranted for some nuclides, such as 3He. They also of in situ nuclide production. To allow nonspecialists to indicate that the larger contribution of protons at high perform these analyses, user-friendly calculators are now elevations, which are undercounted by neutron monitors available (e.g. Balco et al. 2008). The scaling factors that (Clem and Dorman 2000), needs to be considered for are currently used perform well for generally describing nuclide production. the relative flux of cosmic rays as a function of altitude, latitude (Stone 2000; Dunai 2001; Desilets and Zreda 2003; CONCLUSIONS Balco et al. 2008; Lifton et al. 2008), variations in geomag-netic field strength (Dunai 2001; Desilets and Zreda 2003; This brief review presents the fundamental principles of Lifton et al. 2008), and changes in solar activity (Lifton cosmogenic nuclide production in the atmosphere and in et al. 2008). At latitudes greater than 30º and elevations terrestrial settings. The foundations for this science were below 3 km, their results are generally very similar (Balco initially laid over 50 years ago, but recent advances in our et al. 2008). However, large differences between models abilities to model temporal variations in nuclide produc-(up to 30%) emerge for estimates at lower latitudes and tion are certain to propel the field forward. In the coming higher elevations. These variations arise from the different years, these developments will help to ensure that the neutron flux proxies used (neutron monitors, photographic rapid progress in accurately measuring cosmogenic nuclides emulsions) and their responses to changes in the neutron (Christl et al. 2014 this issue) will be matched by our under-energy spectrum (Lifton et al. 2014). standing of the rates at which these nuclides are produced.

Recent advances have made it feasible to consider the ACKNOWLEDGMENTS temporal changes in the energy spectrum quantitatively and estimate their influence on nuclide production The authors thank Pieter Vermeesch, Greg Balco, and an (Argento et al. 2013; Lifton et al. 2014). Previously, this anonymous reviewer for their constructive and helpful omission was due to the lack of detailed environmental comments on the manuscript.

REFERENCES Argento DC, Reedy RC, Stone JO (2013)

Modeling the earth’s cosmic radiation. Nuclear Instruments & Methods in Physics Research Section B 294: 464-469

Balco G, Stone JO, Lifton NA, Dunai TJ (2008) A complete and easily acces-sible means of calculating surface exposure ages or erosion rates from 10Be and 26Al measurements. Quaternary Geochronology 3: 174-195

Christl M, Wieler R, Finkel RC (2014) Measuring one atom in a million billion with mass spectrometry. Elements 10: 330-332

Clem JM, Dorman LI (2000) Neutron monitor response functions. Space Science Reviews 93: 335-359

Desilets D, Zreda M (2003) Spatial and temporal distribution of secondary cosmic-ray nucleon intensities and applications to in situ cosmogenic dating. Earth and Planetary Science Letters 206: 21-42

Diehl R and 15 coauthors (2006) Radioactive 26Al from massive stars in the Galaxy. Nature 439: 45-47

Dunai TJ (2001) Influence of secular variation of the geomagnetic field on production rates of in situ produced cosmogenic nuclides. Earth and Planetary Science Letters 193: 197-212

Dunai TJ (2010) Cosmogenic Nuclides: Principles, Concepts and Applications in the Earth Surface Sciences. Cambridge University Press, Cambridge, 198 pp

Eidelman S and 33 coauthors (2004) Review of particle physics. Physics Letters B592: 1-1109

Gosse JC, Phillips FM (2001) Terrestrial in situ cosmogenic nuclides: theory and application. Quaternary Science Reviews 20: 1475-1560

Heikkilä U, Beer J, Abreu JA, Steinhilber F (2013) On the atmospheric transport and deposition of the cosmogenic radio-nuclides (10Be): A review. Space Science Reviews 176: 321-332

Lal D (1991) Cosmic ray labeling of erosion surfaces: in situ nuclide produc-tion rates and erosion models. Earth and Planetary Science Letters 104: 424-439

Lal D, Peters B (1967) Cosmic ray produced radioactivity on earth. In: Flugg S (ed) Handbook of Physics, vol 46/2. Springer, Berlin, pp 551-612

Leya I, Lange H-J, Neumann S, Wieler R, Michel R (2000) The production of cosmogenic nuclides in stony meteor-oids by galactic cosmic-ray particles. Meteoritics & Planetary Science 35: 259-286

Lifton NA, Smart DF, Shea MA (2008) Scaling time-integrated in situ cosmo-genic nuclide production rates using a continuous geomagnetic model. Earth and Planetary Science Letters 268: 190-201

Lifton N, Sato T, Dunai TJ (2014) Scaling in situ cosmogenic nuclide production rates using analytical approximations

to atmospheric cosmic-ray fluxes. Earth and Planetary Science Letters 386: 149-160

Masarik J, Beer J (1999) Simulation of particle fluxes and cosmogenic nuclide production in the Earth’s atmosphere. Journal of Geophysical Research D 104: 12099-12111

Reedy RC (2013) Cosmogenic-nuclide production rates: Reaction cross section update. Nuclear Instruments & Methods in Physics Research Section B 294: 470-474

Rossi B (1964) Cosmic Rays. McGraw-Hill, New York, 268 pp

Sato T, Yasuda H, Niita K, Endo A, Sihver L (2008) Development of PARMA: PHITS-based analytical radiation model in the atmosphere. Radiation Research 170: 244-259

Stone JO (2000) Air pressure and cosmo-genic isotope production. Journal of Geophysical Research 105(B10): 23753-23759

von Blanckenburg F, Willenbring JK (2014) Cosmogenic nuclides: Dates and rates of Earth-surface change. Elements 10: 341-346

Willenbring JK, von Blanckenburg F (2010) Meteoric cosmogenic Beryllium-10 adsorbed to river sediment and soil: Applications for Earth-surface dynamics. Earth-Science Reviews 98: 105-122

ELEMENT S 350 OCT OBE R 2014

Cosmogenic Nuclides and Erosion at the Watershed Scale

Darryl E. Granger1 and Mirjam Schaller2

1811-5209/14/0010-369$2.50 DOI: 10.2113/gselements.10.5.369

Landscapes are sculpted by a variety of processes that weather and erode bedrock, converting it into soils and sediments that are moved downslope. Quantifying erosion rates provides important insights into a wide range of questions in disciplines from tectonics and landscape evolu-tion to the impacts of land use. Cosmogenic nuclides contained in quartz sediment provide a robust tool for determining spatially averaged erosion rates across scales ranging from single hillslopes to continental river basins and are providing fundamental clues to how landscapes evolve. Cosmogenic nuclides in buried sediments contain unique information about paleo–erosion rates up to millions of years in the past. This article explores some of the basic ideas behind various methods used to infer catchment-wide erosion rates and highlights recent examples related to problems in tectonics, climate, and land use.

KEYWORDS: cosmogenic nuclide, erosion, paleoerosion, river sediment

INTRODUCTION At the grandest scale, Earth’s topography represents an accumulation of potential energy from mantle convection and tectonics, balanced by decay from chemical weath-ering and physical erosion. Over timescales of 103–106

years, hillslope erosion, soil formation, and sediment accumulation define the distribution and fertility of soil upon which our societies depend. There is a critical need to understand how soil erosion from land use is depleting this natural resource and how modern rates compare with those from the past. Climate change also affects erosional processes in complicated ways, which can be difficult to discern without accurate measurements of erosion rates over various timescales.

Curiously, the problem is that the rate of erosion is a tricky thing to measure. It is a measure of something that isn’t there anymore, and of how quickly it went away. What is needed is a sensitive way to measure how much material was once at a given place and the rate at which that material was lost to dissolution, erosion, and sediment transport. There have been a number of traditional approaches to the problem. For example, over long timescales (millions of years), one can use thermochronology to infer the rate of rock cooling due to exhumation by erosion from kilometers below the surface (Reiners and Shuster 2009).

1 Department of Earth, Atmospheric, and Planetary Sciences Purdue University, West Lafayette, IN 47907-2051, USA E-mail: dgranger@purdue.edu

2 Department of Geosciences, University of Tübingen 72074 Tübingen, Germany E-mail: mirjam.schaller@uni-tuebingen.de

Cosmogenic nuclides in sand from an active river

bed (here in the Pamir Mountains) disclose the modern erosion rate of

an entire watershed. Sediment from river

terraces (like those seen beneath the village)

provides the “paleo– erosion rate”: the

erosion rate prevailing at the time of sediment

deposition. PHOTO COURTESY OF ELENA GRIN

Over very short timescales of years to decades, sediment and solute fluxes from a watershed can be monitored, but these measure-ments are difficult to make with accuracy and may not capture important but infrequent events. A better approach over timescales from decades to millennia is to measure sediment acc umula-tion in lakes and reservoirs or in datable sedimentary deposits, such as alluvial fans. Unfortunately, these measurements requ ire special circumstances and can be

subject to considerable uncertainty due to spatial variations in sedimentation rate and in sediment-trapping efficiency. There is an important middle ground over timescales of 103–105 years in which rocks weather and soils form, climate changes from glacial to interglacial, rivers incise or aggrade, and civilizations rise and fall. This is the timescale that belongs to cosmogenic nuclides. Over the past two decades, cosmogenic nuclides have emerged as the method of choice for inferring erosion rates over spatial scales that can be as small as a single outcrop to as large as watersheds spanning a continent.

DETERMINING EROSION RATES

Theory and Methods Cosmogenic nuclides such as 10Be (half-life, t1/2, = 1.39 My) and 26Al (t1/2 = 0.702 My) are produced in minerals such as quartz by reactions with secondary cosmic ray neutrons, protons, and muons (for details see Dunai and Lifton 2014 this issue). These nuclides can be used to infer erosion rates because their production rates within a mineral grain depend on their proximity to the Earth’s surface. Production rates decrease exponentially with depth in rock or soil (with a mean cosmic ray penetration length of ~60 cm in rock of density 2.6 g cm-3). For an eroding surface, this means that the cosmogenic nuclide concentration integrates the history of a grain’s approach toward the surface. In other words, the cosmogenic nuclide concentration contained in a mineral grain today reflects how quickly the overlying mass went away.

Mathematically, it can be shown that the cosmogenic nuclide concentration in an eroding rock is inversely proportional to erosion rate (Lal 1991). Erosion, as used

ELEMENT S, VOL . 10, PP. 369–373 369 OCT OBE R 2014

mailto:dgranger@purdue.edumailto:mirjam.schaller@uni-tuebingen.dehttp:1811-5209/14/0010-369$2.50

IGURE

-

• •

here, refers to the combination of physical erosion and chemical weathering that removes mass near the surface. Early in the development of cosmogenic nuclide applica-tions, it was recognized that bedrock outcrops can be used to determine the denudation history of that particular rock. However, in the mid-1990s researchers realized that cosmo-genic nuclides in detrital sediment grains can also be used to determine erosion rates [for reviews see Bierman and Nichols (2004) and Granger and Riebe (2013)].

Two key realizations led to interpreting cosmogenic nuclides in sediment. The first was that for a well-mixed soil eroding at steady state (and in the absence of a high degree of chemical weathering within the soil), the average concentration of cosmogenic nuclides in the soil is the same at all soil depths. This concentration is equal to the concentration contained in the surface of a rock outcrop eroding at the same rate. In other words, for a given erosion rate, a sample of well-mixed soil has exactly the same concentration as exposed bedrock. The effects of chemical weathering are somewhat more complex, as they vary with depth, and an entire research field has emerged dedicated to interpreting weathering rates with cosmogenic nuclides (e.g. Dixon and Riebe 2014 this issue).

The second key to interpreting cosmogenic nuclides in sediment is that for well-mixed stream sediment, the average concentration in the sediment yields the average erosion rate in the watershed (FIG. 1). This relies on the assumptions that sediment is supplied at a rate that is proportional to the erosion rate, that the mineral being analyzed (i.e. quartz) is evenly distributed throughout the entire catchment, and that the cosmogenic nuclide in question was absent before the rock approached the surface.

It is worth examining these assumptions in detail. We begin with the idea that detrital sediment from well-mixed soil on a hillslope has a cosmogenic nuclide concentration that is inversely proportional to the hillslope erosion rate. For a watershed that is eroding homogeneously (i.e. every-where at the same rate), then the concentration in stream sediment is equal to that of the soils on the hillslopes and the stream sediment yields the erosion rate. In most cases we can ignore sediment storage and transport time in the stream system, which occurs much faster than the timescale of erosion rates, that is, the time to erode the landscape by 60 cm. For a watershed that is eroding heterogeneously, a surprisingly simple solution emerges if we consider the flux-averaged cosmogenic nuclide concentration. That is, areas of the landscape that are eroding quickly provide a large fraction of the quartz but have a low cosmogenic nuclide concentration; conversely, areas eroding slowly provide less quartz but have a high cosmogenic nuclide concentration. In this case, the average cosmogenic nuclide concentration in the sediment reflects the spatially averaged erosion rate from the entire watershed. Remarkably, the equation to determine the erosion rate from an entire watershed is functionally identical to the equation used to determine the erosion rate from a single eroding outcrop. For example, the cosmogenic nuclides contained in a single sample of sand can yield the spatially averaged erosion rate of a water-shed ranging in size from the catchment of a small upland creek to the entire Amazon River basin (FIG. 2; Wittmann et al. 2011).

While the assumption of well-mixed and representative stream sediment may hold approximately true, landslides or other such episodic events may deliver an overwhelming load of sediment that temporarily biases the average. If the preponderance of a sample comes from just one landslide, then the inferred erosion rate will reflect primarily only that area. Moreover, if the landslide incorporates fresh

Cosmic rays Cosmic rays

Cosmogenic nuclide production

Landslide (non-steady erosion)

If production = export Sediment storage in for steady erosion, no decay

N = P L/ ε terraces

N: Nuclide concentration P : Average production rate L: Cosmic ray penetration depth (R/l ≈ 60 cm) ¡: Catchment-averagederosionrate

Cosmogenic nuclide export from the landscape

FIGURE 1 An eroding landscape provides sediment that can be analyzed to determine its erosion rate. Because cosmo-genic nuclide concentrations are inversely proportional to erosion rates, the flux-weighted 10Be concentration reflects the spatially averaged erosion rate. Care must be taken to avoid the influence of landslides, which can temporarily bias the sediment budget, and to avoid catchments with extensive sediment storage. Sediment in archives such as terraces can be used to determine paleo–erosion rates at the time of sediment deposition. Penetration length Λ = 160 g cm-2; density ρ = 2.6 g cm-3 .

F 2 Sampling river sand for cosmogenic nuclide determi-nation in the Qilian Shan, northern China. A single

sample of 10–100 g of quartz can yield the spatially averaged erosion rate of the sediment-contributing area upstream. PHOTO COURTESY OF KAI HU

bedrock or saprolite, then the cosmogenic nuclide concen-tration will be lowered and the inferred erosion rate will be faster than the long-term average. On the other hand, if landsliding dominates sediment delivery in the water-shed, then it is important to sample that material or the inferred erosion rate will be too slow. The best solution is to sample a sufficiently large catchment with enough landslides so that any single event does not significantly influence the average cosmogenic nuclide concentration (e.g. Yanites et al. 2009).

Timescale of Erosion The timescale over which in situ–produced cosmogenic nuclides measure erosion rates is one of the major strengths of the method, but this also limits the sorts of problems

ELEMENT S 370 OCT OBE R 2014

-

Appa

rent

ero

sion

rate

(m/M

y)

200

100

Actual erosion rate

0 0 5 10 15 20

Time (ky)

FIGURE 3 The apparent erosion rate inferred from cosmogenicnuclides can take thousands of years to respond to an actual change in surface erosion rates. The response time, or the time it takes for the apparent erosion rate to match the real erosion rate, depends on both the erosion rate and the soil thickness. The graph shows the apparent erosion rate in response to a step change in erosion rate from 100 to 200 m/My, for soil thicknesses of 0, 100, and 200 cm, calculated for typical rock density of 2.6 g cm-3 and soil density of 1.5 g cm-3. For thin soils the apparent erosion rate has increased by 90% of the actual change within ~9 ky, while for 200 cm thick soils the same increase in apparent erosion rates takes over 15 ky.

to which cosmogenic nuclides can be applied. Because cosmogenic nuclides integrate the history of production rates and because production rates fall off exponentially with depth, for a steady erosion rate the concentration is equivalent to the mineral residence time within the top 160 g cm-2 (~60 cm in rock of density 2.6 g cm-3, or ~1 m in soil of density 1.6 g cm-3). In other words, the timescale of bedrock erosion is equal to the time it takes to lower the landscape by ~60 cm, roughly equivalent to the timescale of soil formation in many landscapes. This timescale implies that cosmogenic nuclides effectively dampen rapid changes in erosion rate. If erosion rates change suddenly— for example, due to recent land use or climate change— then the cosmogenic nuclide concentration in the soil will change only slowly, with a response time determined by both the soil mixing depth and the time taken to erode ~60 cm of rock (FIG. 3). The damped response time means that the cosmogenic nuclide concentration measured in soils today represents the long-term average erosion rate, which is usually independent of recent changes in land use and soil degradation.

Examples of Catchment-Wide Erosion Rates Over the past 20 years, erosion rates have been estimated by measuring the cosmogenic nuclides contained in thousands of river-sediment samples from virtually every climatic and tectonic environment in the world (e.g. Portenga and Bierman 2011; Covault et al. 2013 and references therein). Generally, these erosion rates are based on the measure-ment of 10Be produced in situ in quartz. Several persistent themes have emerged from the data.

One surprising conclusion from these cosmogenic nuclide– based erosion rates is that climate is less important for regulating erosion rates than previously assumed. While erosion rates certainly vary strongly under conditions of climatic extremes where erosional processes are fundamen-tally different (for example, erosion is slow in hyperarid deserts with little biological activity and fast in glacial and periglacial environments), climate generally plays a secondary role in determining erosion rates over most of the planet. Climate strongly affects the degree of soil

weathering (Dixon and Riebe 2014), but the total erosion rate is more commonly determined by factors such as river and hillslope gradients that are adjusted to balance local uplift. Thus, erosion rates on low-relief continental shields are generally slow regardless of climate (~1–10 m/My), while they are much faster (~103–104 m/My) on rapidly uplifting mountain ranges.

The conclusion that landscape erosion rates are ultimately set by tectonics driving river incision and hillslope erosion rather than by climate has a number of implications. Perhaps the most important is that cosmogenic nuclide– based erosion rates can be used as a proxy for local river incision and uplift rates (e.g. Wobus et al. 2005). This is a powerful notion for landscapes at dynamic equilibrium because it suggests that a handful of sand can provide the local incision and uplift rates (Kirby and Whipple 2012).

The numerous cosmogenic nuclide measurements now available allow comparison of erosion rates over different timescales. Catchment-averaged erosion rates from cosmo-genic nuclides can be compared to short-term suspended-and dissolved-sediment loads in rivers (e.g. Wittmann et al. 2011; Covault et al. 2013). Interestingly, Covault et al. (2013) found that the vast majority of cosmogenic nuclide–based erosion rates are faster than those inferred from monitored sediment yield. This tendency was first noticed by Kirchner et al. (2001), who invoked the impor-tance of large but infrequent events in sediment delivery. While the abundances of cosmogenic nuclides average such variability, stream-gauging methods are likely to miss the largest and most important events that may happen only once in a decade or a century. In addition, sediment storage in floodplains tends to buffer rapid changes in sediment supply due to land use (Wittmann et al. 2011). Only in the most highly modified landscapes or in landscapes with very low sediment storage capacity do modern erosion rates consistently exceed cosmogenic nuclide–based erosion rates (e.g. Hewawasam et al. 2003).

PALEO–EROSION RATES If modern-day river sediment contains information about the erosion rate of its source area, then sedimentary deposits should be able to tell us about paleo–erosion rates and how erosion rates have varied through time in response to changes in climate or tectonics.

Estimates of paleo–erosion rates provide powerful insights into the behavior of ancient landscapes. It must be recog-nized, however, that the cosmogenic nuclides that are generally useful for determining erosion rates, such as 10Be and 26Al in quartz, are radioactive. Also, cosmogenic nuclide production does not fully stop even after several meters of burial. Thus, accurate paleo–erosion rate determi-nations require correcting for loss due to radioactive decay as well as continued production by deeply penetrating muons. The slower the paleo–erosion rate and the more deeply buried the sediment, the further back in time one can infer paleo–erosion rates—generally up to 5–10 million years.

Of course, accurate paleo–erosion rate determinations require knowing the depositional age of the sediment. But what if the age is not known independently? The beauty of cosmogenic nuclides is that it is possible to date the sediment directly using “burial dating.” Measuring at least two nuclides in the same mineral grains (such as 10Be, 26Al, and/or 21Ne in quartz; Balco and Shuster 2009) allows one to solve for the burial age and the paleo–erosion rate simultaneously.

ELEMENT S 371 OCT OBE R 2014

-

• • • • ,.e

[ - I

tt.~.. . .. . . I 1~~-.... I t= --1 ~:. -~ I

Examples of Paleo–erosion Rates A good example of how paleo–erosion rates can be estimated over glacial/interglacial timescales comes from the pioneering work of Schaller et al. (2002). In their study of sediments in terraces of European rivers, they found that erosion rates were roughly twice as fast during the Last Glacial Maximum (LGM) as they are today. Estimates show that the ~80 m/My determined for the LGM became much slower, to ~30–40 m/My, through the Holocene to the present. The faster rates may be due to frost-cracking and/or periglacial processes that accelerated erosion and soil transport during the LGM (e.g. Delunel et al. 2010).

Paleo–erosion rates can also be determined from buried sediment over much longer timescales of millions of years to decipher how landscapes have responded to climate change and tectonic uplift (Schaller et al. 2004). Paleo– erosion rates (and burial dates) allow one to explore how erosion rates and valley-incision rates have varied at the same site over millions of years, and thus to quantify how landscapes have responded to long-term climate change and uplift. For example, a compilation of paleo–erosion rate determinations that span million-year timescales (FIG. 4) records the varied responses of landscapes to the expan-sion of Northern Hemisphere glaciation near 2.5 My ago. Together these types of studies provide an opportunity to examine the influence of long-term climate change on hillslope erosion rates.

Measurements of cosmogenic nuclides also show that erosion rates have increased in many glaciated or partially glaciated watersheds, even during interglacials. This is true in the northern Swiss Alps (Haeuselmann et al. 2007), the Sierra Nevada of California, USA (Stock et al. 2004), and the Tian Shan in China (Charreau et al. 2011) (FIG. 4). Erosion rates have increased in some unglaciated watersheds as well, particularly in areas subject to a periglacial climate. Schaller et al. (2004) found increased erosion in the Meuse River, the Netherlands, likely due to both climate change and uplift of the Ardennes Mountains. A dramatic increase in erosion rate is documented in an unglaciated valley in the Sangre de Cristo Range, Colorado, USA (Refsnider 2010). Anthony and Granger (2007) studied sediment in caves along the Cumberland Plateau in the unglaci-ated southeastern United States and showed that paleo– erosion rates systematically increase in the Pleistocene hundreds of kilometers south of the Laurentide ice sheet margin. Interestingly, data from Mammoth Cave in central Kentucky (Granger et al. 2001) do not show any change in paleo–erosion rates across this same climatic transition, even though the site is closer to the ice margin.

DEVELOPING TRENDS: METEORIC 10BE While the discussion thus far has focused on 10Be produced in situ within mineral grains, there is another, much larger, inventory of meteoric 10Be in soil. 10Be is produced in the atmosphere and delivered to the surface by wet and dry deposition (e.g. Dunai and Lifton 2014). As a fallout radio-

nuclide, meteoric 10Be is incorporated into a variety of archives, including snow and ice; lacustrine, estuarine, and marine sediment; manganese nodules on the sea floor; and soil. Measurements of meteoric 10Be have been used to address a wide range of geologic problems, from snow and ice accumulation to sediment recycling in subduc-tion zones. We focus here on the specific use of meteoric 10Be for determining erosion rates. For recent reviews, see Willenbring and von Blanckenburg (2010), Graly et al. (2010), and Granger et al. (2013).

Meteoric 10Be is a particle-reactive species that adsorbs strongly to mineral grains, particularly clays, for soil pH greater than about 6. Unlike in situ–produced 10Be, the meteoric variety migrates within the soil profile, to a depth determined largely by soil pH, soil texture, and grain size. More recently, the 10Be/9Be ratio of beryllium adsorbed to sediment has been used to simultaneously determine the erosion rate and the degree of chemical weathering of bedrock within a watershed. The 10Be is derived from meteoric fallout while the 9Be comes from the chemical weathering of bedrock (von Blanckenburg et al. 2012). Advantages of the meteoric technique are that only ~1 gram of fine-grained material is required and that the 10Be/9Be ratio is nearly independent of lithology.

Tian Shan, China

Sangre de Cristo Mtns., USA

Sierra Nevada, USA

Meuse River, the Netherlands

Pale

o-er

osio

n Ra

te (m

/My)

600 Siebenhengste, Swiss Alps

400

200

0 3000

2000

1000

0 60

40

20

0 60

40

20

0 10

8 6 4 2

0 600

400

200

0 80

60

40

20

0

Cumberland Plateau, USA

Mammoth Cave, USA

0 1 2 3 4 5 6 7 8 9

Age (My)

FIGURE 4 Paleo–erosion rates from ancient sediment as a function of time for seven northern-latitude sites that

span at least 1 million years. All but one show increasing erosion rates and/or erosional variability, whether for slowly eroding landscapes such as the Cumberland Plateau, USA, or the Meuse River in the Netherlands where maximum erosion rates are 60 m/ My or for high mountains such as the Swiss Alps or the Tian Shan, China, eroding more than 10 times faster. All ages and erosion rates are plotted as originally reported by the authors (cited in the text) and have not been adjusted to a uniform 10Be production rate and half-life, which would result in minor changes.

ELEMENT S 372 OCT OBE R 2014

During the early years of cosmogenic nuclide applica-tions, meteoric 10Be was widely used for exploring surface processes because of its relatively high atmospheric concen-trations. This approach, however, was largely eclipsed by measurements of the in situ–produced variety in the early 1990s as methods were developed for determining 10Be contained in quartz. Recent years have seen a resurgence in the meteoric variety’s popularity, but one must recog-nize that beryllium mobility in the environment can be complex and is still poorly understood. Meteoric 10Be holds great promise for exploring erosion rates and sediment transport, as well as changing environmental conditions.

SUMMARY Cosmogenic nuclides are now the “gold standard” for deter-mining erosion rates of rocks and watersheds. The method is rooted in the physics of energetic-particle attenuation,

which allows geologists to query a rock about the material that used to be on top of it and the rate at which the material was lost. A handful of sand from a riverbed can tell us about the average erosion rate upstream. Sedimentary archives offer a unique record of how erosion rates have changed through time. Cosmogenic nuclides are finally allowing geologists to answer age-old questions about how the landscapes and soils around us reflect their combined legacy of climate, tectonics, and land use.

ACKOWLEDGMENTS We would like to acknowledge the helpful comments by the guest editors as well as reviews by P. Belmont, B. Bookhagen, and V. Godard.

REFERENCES Anthony DM, Granger DE (2007) A new

chronology for the age of Appalachian erosional surfaces determined by cosmogenic nuclides in cave sediments. Earth Surface Processes and Landforms 32: 874-887

Balco G, Shuster DL (2009) 26Al–10Be–21Ne burial dating. Earth and Planetary Science Letters 286: 570-575

Bierman PR, Nichols KK (2004) Rock to sediment—slope to sea with 10Be—rates of landscape change. Annual Review of Earth and Planetary Sciences 32: 215-255

Charreau J and 11 coauthors (2011) Paleo-erosion rates in Central Asia since 9 Ma: A transient increase at the onset of Quaternary glaciations? Earth and Planetary Science Letters 304: 85-92

Covault JA, Craddock WH, Romans BW, Fildani A, Gosai M (2013) Spatial and temporal variations in landscape evolu-tion: Historic and longer-term sediment flux through global catchments. Journal of Geology 121: 35-56

Delunel R, van der Beek PA, Carcaillet J, Bourlès DL, Valla PG (2010) Frost-cracking control on catchment denudation rates: Insights from in situ produced 10Be concentrations in stream sediments (Ecrins–Pelvoux massif, French Western Alps). Earth and Planetary Science Letters 293: 72-83

Dixon JL, Riebe CS (2014) Tracing and pacing soil across slopes. Elements 10: 363-368

Dunai TJ, Lifton NA (2014) The nuts and bolts of cosmogenic nuclide production. Elements 10: 347-350

Graly JA, Bierman PR, Reusser LJ, Pavich MJ (2010) Meteoric 10Be in soil profiles – A global meta-analysis. Geochimica and Cosmochimica Acta 74: 6814-6829

Granger DE, Riebe CS (2013) Cosmogenic nuclides in weathering and erosion. In: Drever JI (ed) Surface and Groundwater, Weathering and

Soils. Treatise on Geochemistry 5, Elsevier, 36 pp, doi:10.1016/ B978-0-08-095975-7.00514-3

Granger DE, Fabel D, Palmer AN (2001) Pliocene–Pleistocene incision of the Green River, Kentucky, determined from radioactive decay of cosmogenic 26Al and 10Be in Mammoth Cave sediments. GSA Bulletin 113: 825-836

Granger DE, Lifton NA, Willenbring JK (2013) A cosmic trip: 25 years of cosmo-genic nuclides in geology. GSA Bulletin 125: 1379-1402

Haeuselmann P, Granger DE, Jeannin P-Y, Lauritzen S-E (2007) Abrupt glacial valley incision at 0.8 Ma dated from cave deposits in Switzerland. Geology 35: 143-146

Hewawasam T, von Blanckenburg F, Schaller M, Kubik P (2003) Increase of human over natural erosion rates in tropical highlands constrained by cosmogenic nuclides. Geology 31: 597-600

Kirby E, Whipple KX (2012) Expression of active tectonics in erosional landscapes. Journal of Structural Geology 44: 54-78

Kirchner JW and 6 coauthors (2001) Mountain erosion over 10 yr, 10 k.y., and 10 m.y. time scales. Geology 29: 591-594

Lal D (1991) Cosmic ray labeling of erosion surfaces: in situ nuclide produc-tion rates and erosion models. Earth and Planetary Science Letters 104: 424-439

Portenga EW, Bierman PR (2011) Understanding Earth’s eroding surface with 10Be. GSA Today 21(8): 4-10

Refsnider KA (2010) Dramatic increase in late Cenozoic alpine erosion rates recorded by cave sediment in the southern Rocky Mountains. Earth and Planetary Science Letters 297: 505-511

Reiners PW, Shuster DL (2009) Thermochronology and landscape evolution. Physics Today 62: 31-36

Schaller M, von Blanckenburg F, Veldkamp A, Tebbens LA, Hovius N, Kubik PW (2002) A 30 000 yr record of erosion rates from cosmogenic 10Be in Middle European river terraces. Earth and Planetary Science Letters 204: 307-320

Schaller M, von Blanckenburg F, Hovius N, Veldkamp A, van den Berg MW, Kubik PW (2004) Paleoerosion rates from cosmogenic 10Be in a 1.3 Ma terrace sequence: Response of the River Meuse to changes in climate and rock uplift. Journal of Geology 117: 127-144

Stock GM, Anderson RS, Finkel RC (2004) Pace of landscape evolution in the Sierra Nevada, California, revealed by cosmogenic dating of cave sediments. Geology 32: 193-196

von Blanckenburg F, Bouchez J, Wittmann H (2012) Earth surface erosion and weathering from the10Be (meteoric)/9Be ratio. Earth and Planetary Science Letters 351-352: 295-305

Willenbring JK, von Blanckenburg F (2010) Meteoric cosmogenic Beryllium-10 adsorbed to river sediment and soil: Applications for Earth-surface dynamics. Earth-Science Reviews 98: 105-122

Wittmann H, von Blanckenburg F, Maurice L, Guyot J-L, Filizola N, Kubik PW (2011) Sediment production and delivery in the Amazon River basin quantified by in situ-produced cosmo-genic nuclides and recent river loads. GSA Bulletin 123: 934-950

Wobus C, Heimsath A, Whipple K, Hodges K (2005) Active out-of-sequence thrust faulting in the central Nepalese Himalaya. Nature 434: 1008-1011

Yanites BJ, Tucker GE, Anderson RS (2009) Numerical and analytical models of cosmogenic radionuclide dynamics in landslide-dominated drainage basins. Journal of Geophysical Research Earth Surface 114: doi: 10.1029/2008JF001088

ELEMENT S 373 OCT OBE R 2014

,&3 6DPSOH ,QWURGXFWLRQ 6ROXWLRQV IRU *HRFKHPLVWU\ � from the leader in fluoropolymer manufacturing

Savillex Corporation “Geochemistry would has been proudly

not be where it is serving the today if it were not for geochemistry Savillex Corporation.” community for over 35

years. –Dr.MikeCheatham, Our fluoropolymer Syracuse University labware products are

used throughout the world for sample digestion, separations, storage and many other applications. We understand the unique needs of geochemists and now our new line up of ICP-OES and ICP-MS sample introduction products combine the highest performance and the lowest metal background with the ruggedness and reproducibility required for routineanalysis.

All of our ICP sample introduction products are designed, molded and tested in house, using only the highestpuritygradePFAresins.

For technical notes, videos and to find your local Savillex distributor, visit www.savillex.com.

Savillex Corporation Phone: 952.935.4100 | Fax: 952.936.2292 Email: info@Savillex.com | www.savillex.com

Nebulizers – C-Flow

• C-Flow microconcentric PFA nebulizer range with the narrowest uptake rate specification

• New C-Flow 35 with uptake rate of

35uL/min+/-7uL/min • C-Flow range for desolvators – standard fitment on the CETAC Aridus II

• C-Flow 700d with removable uptake line for high solids applica-tions – up to 25% TDS

• All C-Flows can be backflushed without tools

Inert Kits

• PFA kits with Scott type chamber • True double pass design gives lower RSDs

• O-ring free end cap • Platinum or sapphire injectors • Available for Agilent 7500/7700/8800 and Thermo Element 2/Neptune

1(:! 3XULOOH[é)(3DQG

3)$ %RWWOHV • Lowest metal background • Highest seal integrity

http://www.savillex.com/mailto:info@Savillex.comhttp://www.savillex.com/

Climate Change Response Program National Park Service U.S. Department of the Interior

Climate Change Direct Hire Authority Internship Opportunities in the National Park Service

The implications of climate change are challenging and far-reaching, particularly for land managers tasked with protecting the resources of national parks and other protected areas. To meet this challenge, managers need to encourage and make use of the creative and innovative thinking of the next generation of youth scientists and leaders.

The George Melendez Wright Initiative for Young Leaders in Climate Change (YLCC) builds a pathway for exemplary students in higher education to apply cutting-edge climate change knowledge to park management. Through a summer-long internship, undergraduate and graduate students will gain valuable work experience, explore career options, and develop leadership skills under the mentorship and guidance of the National Park Service. Parks and programs will increase their capacity to understand and respond to climate change and its impacts.

National parks and NPS programs develop and oversee structured projects in one or more of the following interdisciplinary areas: climate change science and monitoring; resource conservation and adaptation; policy development; sustainable park operations; facilities adaptation; and communication/interpretation/education. During the internship, students apply critical thinking and problem solving skills to climate change challenges and communicate with diverse stakeholders. Interns who successfully complete the YLCC, an approved Direct Hire Authority Internship program, will be eligible to be hired non-competitively into subsequent federal jobs once they complete their degree program. These jobs would be in the Department of Interior (DOI), NPS, or one of the other bureaus within the DOI. An intern must qualify for the job in order to be hired non-competitively.

Quick Facts and Deadlines:

• The YLCC is managed cooperatively with the University of Washington • Internship opportunities and application forms are posted on

parksclimateinterns.org • Internships are 11-12 weeks (40 hours/week) during the summer • Interns are paid $14/hour plus benefits • Applications are accepted from early December 2014 until late

January 2015

Who was George Melendez Wright?

George Melendez Wright was deeply influential in bringing science to the management of America’s national parks. Working as a naturalist in Yosemite National Park in the 1920s, Wright argued that good science was needed for effective conservation. In 1930, he was appointed Chief of the Wildlife Division for the NPS where he encouraged the agency to embrace science-based approaches to conserving species, habitats, and other natural conditions in the parks. Although he died while he was still a young man, Wright’s legacy lives on in the NPS’s commitment to use the best available science for preserving the resources of our National Parks.

For More Information: Tim Watkins, Climate Change Response Program, NPS, Tim_Watkins@nps.gov

mailto:Tim_Watkins@nps.govhttp:parksclimateinterns.org

t: Michael R. Pence Governor \i !J Jerome M.Adams, MD,MPH. : j,./ State Health Commissioner Indiana State

De12artment of Health An Equal Opporlunny Employer

October 29, 2014

To College and University Administrators:

The first cases of Ebola Virus Disease (EVD) diagnosed in the United States have heightened awareness of our global community and this serious disease. Italso raised the level of concern for the safety of travelers both to the affected counh·ies, and those returning to Indiana from an affected country, and the safety of the academic community.

The Ebola virus is not spread through the air, by water or food, or by casual contact. People with Ebola can only spread the Ebola virus when they have symptoms. There is no lmown risk of transmission if someone does not have symptoms. Ebola is only spread through direct contact with blood or body fluids (including but not limited to urine, saliva, feces, vomit and semen, or a needlestick) of a person who is sick with Ebola or the body of a person who has died from Ebola.

Currently in the U.S., individua ls at risk for developing EVD are those who have arrived in the U.S. from Guinea, Liberia, or Sierra Leone within the past 21 days (the maximum incubation period for Ebola virus). Previous travel to these countries outside the 21-day incubation period is not a risk factor for Ebola.

Individuals who have had direct contact with identified Ebola cases in the U.S. may also be at risk for the EVD if that contact occurred at the time the case was symptomatic. Ebola symptoms include fever, headache, nausea, vomiting, diaIThea, muscle or body aches, and fatigue. The Indiana State Department of Health (ISDH) website has more information about EVD at www.statehealth .in.gov.

The Centers for Disease Control and Prevention (CDC) has prepared a document specifically addressing the unique concerns of colleges, universities , and students around the EVD occurring in the West African countries of Guinea, Liberia, and Sierra Leone. You can find that information at: http://wwwnc.cdc .gov/travel/page/advice-for-college s-universities-and-student s-about-ebola-in -west-africa.

The CDC has issued a Level 3 Warning travel advisory, urging all U.S. residents to avoid non-essential travel to Liberia, Guinea, and Sierra Leone because of unprecedented outbreaks of Ebola in these countries. In addition, the CDC is screening all passengers departing from airports in Liberia, Guinea, or Sierra Leone for contacts with persons diagnosed with Ebola and symptoms of Ebola. Exit screening involves travelers responding to a traveler health questionnaire, being visually assessed for potential illness, and having their body temperature measured before they board the flight. Passengers with a positive screen are not permitted to board flights.

To augment the screening process, the CDC Division of Global Migration and Quarantine began screening passengers from Liberia, Guinea, and Sierra Leone arriving at five U .S. ports of entry on October 11, 2014. Beginning this weekend, all passengers traveling from these countries will be routed through the five aiiports where screening has been established. Passengers will complete a health assessment form, provide destination and contact information, and have their temperature checked. Anyone with risk factors for Ebola will be further evaluated on site at the airport by a CDC medical officer. Arriving passengers with symptoms will be

O 2NorthMeridian Street•lndlanapolls, IN46204 1 Topromote andprovide 317.233.1325 tdd 317.233.5577 essential public health services indiana 1 www.statehealth.ln.gov · AStatethat

http://wwwnc.cdc/http://www.statehealth.ln.gov/www.statehealth

transported to a designated hospital for medical evaluation in the mTival city. Those with risk factors will be restricted from traveling on commercial conveyances (air, bus, train, taxi/limousine) until the 21-day incubation period has passed.

Travelers at low risk will be allowed to proceed to their destinations, with notification provided to the state health department. The ISDH has already begun receiving notification about any traveler with Indiana as a destination and has an established system, with local public health officials, for monitoring these travelers for fever and other symptoms, so they can be immediately hospitalized should they develop symptoms of Ebola. All passengers arriving from the Liberia, Guinea, and Sierra Leone, regardless of their exposure level, will be monitored by ISDH and local health depmiments twice daily for 21 days. This includes, checking temperature and symptoms.

To read more about enhanced screening of travelers from Liberian, Guinea, and Sierra Leone at airpo1is in the U.S.,pleasevisit the CDCwebsite at:http://www.cdc.gov/media/releases/2014/p1008-ebola-screening.html. CDC has strongly recommended that people avoid non-essential travel to Guinea, Liberia, or SierraLeone at