Speculations on Human and Climate-Speculations on Human and Climate-Change Alteration of Iron Input to Change Alteration of Iron Input to Upwelling Areas off Oregon and Upwelling Areas off Oregon and

WashingtonWashington

David A. Jay, Philip M. Orton and David A. Jay, Philip M. Orton and Thomas A. ChisholmThomas A. Chisholm

Department of Environmental Science and Department of Environmental Science and Engineering, OGI School of Science and Engineering, OGI School of Science and Engineering, Oregon Health & Science Engineering, Oregon Health & Science

UniversityUniversityResearch supported by the National Science Foundation Research supported by the National Science Foundation

and Bonneville Power Administration. Thanks to Ken Bruland and Bonneville Power Administration. Thanks to Ken Bruland (UCSC) (UCSC)

and Valerie Kelly ( US GS, Portland)and Valerie Kelly ( US GS, Portland)

Why Study Columbia River (CR) Fe Why Study Columbia River (CR) Fe Input?Input?

• CR Plume supports juvenile salmon productivityCR Plume supports juvenile salmon productivity• CR Fe supply may be a major factor in CR Fe supply may be a major factor in

determining plume and coastal productivitydetermining plume and coastal productivity• CR flow regime and fine sediment transport have CR flow regime and fine sediment transport have

been greatly altered; likely Fe input alsobeen greatly altered; likely Fe input also• Region has spent more than $5 billion on salmon, Region has spent more than $5 billion on salmon,

but:but:• Mechanisms of plume productivity are poorly Mechanisms of plume productivity are poorly

understoodunderstood• Effects of CR power system on plume not examinedEffects of CR power system on plume not examined• Role of plume for salmon barely understoodRole of plume for salmon barely understood

• Changing hydropower system to restore Fe input Changing hydropower system to restore Fe input may be economical relative to other “fixes” may be economical relative to other “fixes”

Why are Ideas about CR Fe Input Why are Ideas about CR Fe Input Speculative?Speculative?

• Is Fe input supply or transport capacity limited?Is Fe input supply or transport capacity limited?• Which particulate fractions are bioavailable?Which particulate fractions are bioavailable?• What about transformations in marshes, What about transformations in marshes,

mudflats and floodplain?mudflats and floodplain?• USGS trace metal database is limited, transport USGS trace metal database is limited, transport

models uncertainmodels uncertain• Don’t know whether delivery of particulate Fe Don’t know whether delivery of particulate Fe

to shelf sediments or dissolved to shelf sediments or dissolved Fe (dFe)Fe (dFe) is more is more importantimportant

• N input is also important and has been alteredN input is also important and has been altered• The problem is important – so we forge ahead! The problem is important – so we forge ahead!

Fe Effects on Coastal Productivity off Fe Effects on Coastal Productivity off Oregon and Washington --Oregon and Washington --

Observations Suggest --Observations Suggest --• dFe may be input to surface waters from (Chase et al, dFe may be input to surface waters from (Chase et al,

2002):2002):• Upwelling (appear to be enriched by terrigenous particles on Upwelling (appear to be enriched by terrigenous particles on

shelf; Johnson et al, Nature, 1999)shelf; Johnson et al, Nature, 1999)• Offshore sub-surface watersOffshore sub-surface waters• CR plumeCR plume

• All three sources may reflect CR inputAll three sources may reflect CR input• The OR coast is mildly Fe-stressed (Hutchins et al., Type The OR coast is mildly Fe-stressed (Hutchins et al., Type

2)2)• This level of Fe limitation can disadvantage the large This level of Fe limitation can disadvantage the large

diatoms that support juvenile salmonids’ food webdiatoms that support juvenile salmonids’ food web• WA productivity is higher than OR -- is this partially WA productivity is higher than OR -- is this partially

explained by deposits of Fe-rich CR sediments on WA explained by deposits of Fe-rich CR sediments on WA shelf?shelf?

• This might require a greater degree of Fe limitation…This might require a greater degree of Fe limitation…

• More questions than answers!More questions than answers!

dFe in the CR Plume Area --dFe in the CR Plume Area --

• dFe can be plentiful in the plume (Chase et al, Bruland dFe can be plentiful in the plume (Chase et al, Bruland et al)et al)

• Fe decreases offshore, but may be elevated at fronts Fe decreases offshore, but may be elevated at fronts • Chl peaks as N is supplied to plume by mixing; again Chl peaks as N is supplied to plume by mixing; again

fronts may be importantfronts may be important

June 1997 observations Bruland et al., in preparation

Bruland et al., in preparation

Historical Changes in Columbia Historical Changes in Columbia River River Fe Input to Coastal Waters -- Fe Input to Coastal Waters --

• CR spring flow is down >40% due to flow regulation, irrigationCR spring flow is down >40% due to flow regulation, irrigation• Plume volume is much smaller, 1961 vs. 1999 as example:Plume volume is much smaller, 1961 vs. 1999 as example:

• June 1961 and 1999 “virgin” flows both very high (>20,000 mJune 1961 and 1999 “virgin” flows both very high (>20,000 m33 s s-1-1))• Actual 1999 flow was ~ 11,000 mActual 1999 flow was ~ 11,000 m33 s s-1-1, 1961 was ~20,000 m, 1961 was ~20,000 m33 s s-1-1

• 1999 plume covered only ~65% of area covered in 1961, 1999 plume covered only ~65% of area covered in 1961, • Fe input likely reducedFe input likely reduced

June 1961 Plume

Hydrologic Change and the CR Plume --Hydrologic Change and the CR Plume --

June 1999 Plume

Hindcasting CR dFe Supply:Hindcasting CR dFe Supply:

• Use USGS data and transport models to define Use USGS data and transport models to define sources, seasonality of dFesources, seasonality of dFe

• The Cascades are a potent dFe source, highest dFe The Cascades are a potent dFe source, highest dFe concentrations are found in Willamette (reservoir concentrations are found in Willamette (reservoir removal??)removal??)

• USGS models: CR delivers as much dFe as MississippiUSGS models: CR delivers as much dFe as Mississippi• Particulate Fe is near crustal abundance (~5%), but Particulate Fe is near crustal abundance (~5%), but

much is not available (e.g., in black sands). Not useful much is not available (e.g., in black sands). Not useful to model to model

• Can dFe model be used in historical, hindcast mode?Can dFe model be used in historical, hindcast mode?

1880 vs. 1997 input: Compare Two 1880 vs. 1997 input: Compare Two Very High-Flow Years Very High-Flow Years

1997

1880

Beaver Fe transport, Hindcast from US GS model,95% confidence limits shaded

• Almost all 1997 Fe Almost all 1997 Fe input was in winterinput was in winter

• Big winter freshets are Big winter freshets are of short durationof short duration

• 1880 input was mostly 1880 input was mostly in spring; winter inputs in spring; winter inputs low low

• 95% confidence limits 95% confidence limits indicate high levels of indicate high levels of uncertainty uncertainty

• Controls on fluvial Fe Controls on fluvial Fe inputs not understoodinputs not understood

Beaver Fe transport, Hindcast from US GS model,95% confidence limits shaded

1880 vs. 1997 Seasonal Comparison 1880 vs. 1997 Seasonal Comparison ----

Seasonal Totals

• 1880 had ~twice the total input (150,000 vs 70,000 tons), 1880 had ~twice the total input (150,000 vs 70,000 tons), and 7x the spring input (140,000 vs. 20,000 tons)and 7x the spring input (140,000 vs. 20,000 tons)

• 1997 had much larger winter input (50,000 vs 10,000 tons)1997 had much larger winter input (50,000 vs 10,000 tons)• 1880 vs. 1997 spring freshet change is typical of long-term 1880 vs. 1997 spring freshet change is typical of long-term

change: less dFe input, occurs earlier in season (May vs. June)change: less dFe input, occurs earlier in season (May vs. June)• There were actually more winter floods before 1940There were actually more winter floods before 1940

Important Factors for Spring Freshet Important Factors for Spring Freshet ----

• Estuary residence time has increased:Estuary residence time has increased:• due to dredged channel (increases exposure of water due to dredged channel (increases exposure of water

to peripheral areas)to peripheral areas)• due to reduced spring freshet, no zero-salinity estuary due to reduced spring freshet, no zero-salinity estuary

during spring freshetduring spring freshet

• River residence time has increased:River residence time has increased:• nutrient utilization = F (temperature, clarity, time)nutrient utilization = F (temperature, clarity, time)• particles are lost in storage reservoirsparticles are lost in storage reservoirs

• Need to understand historical changes in Need to understand historical changes in geochemistry from:geochemistry from:• Decreases in SPM transportDecreases in SPM transport• 70% loss of floodplain and marshes through diking70% loss of floodplain and marshes through diking

• Changes to N and Si may also be Changes to N and Si may also be importantimportant

Changes in N and Si Inputs --Changes in N and Si Inputs --

• Eutrophication is NOT aEutrophication is NOT aCR issueCR issue

• N, POM inputs to river N, POM inputs to river have increased, but:have increased, but:• Reservoirs increase T & Reservoirs increase T &

residence time, decreaseresidence time, decrease turbidity turbidity

• Fluvial production up ~4xFluvial production up ~4x• Changes in flow have increased estuary residence time and use Changes in flow have increased estuary residence time and use

of Nof N

• Annual export of N to plume may have decreasedAnnual export of N to plume may have decreased• Biggest decrease in N supply in spring, because there Biggest decrease in N supply in spring, because there

was historically little production in cold, turbid, high-flow was historically little production in cold, turbid, high-flow river river

• Si input likely not changed very much – always in excessSi input likely not changed very much – always in excess

Chl data from Larry Small, OSU

Summary --Summary --

• Primary production in CR plume area is mildly Fe Primary production in CR plume area is mildly Fe stressed stressed

• CR is a huge Fe source to OR-WA shelf, differentiating CR is a huge Fe source to OR-WA shelf, differentiating Pacific NW from California coastPacific NW from California coast

• DEFINITEDEFINITE: Flow regulation has made plume smaller, : Flow regulation has made plume smaller, earlier in seasonearlier in season

• LIKELYLIKELY: There has been a decrease in spring freshet CR : There has been a decrease in spring freshet CR dFe, affecting plume, OR and WA shelvesdFe, affecting plume, OR and WA shelves

• POSSIBLEPOSSIBLE: Impact may also extend further into : Impact may also extend further into California Current, to N. California California Current, to N. California

• This may have reduced total primary production and This may have reduced total primary production and altered food web structure; unfavorable for salmonaltered food web structure; unfavorable for salmon

Fe Input and the CR Power System --Fe Input and the CR Power System --• How can decreased dFe input be reversed?How can decreased dFe input be reversed?• Maybe impossible to quantify the benefit… Maybe impossible to quantify the benefit…

thus, the approach should be low cost!thus, the approach should be low cost!• If spring dFe input is critical, this is If spring dFe input is critical, this is anotheranother

reason to increase spring flows. BUT this is reason to increase spring flows. BUT this is costly.costly.

• If winter particulate input to WA shelf is If winter particulate input to WA shelf is critical, then there is an “easy” fix:critical, then there is an “easy” fix:• Time winter reservoir drawdown to coincide with Time winter reservoir drawdown to coincide with

northward flow on shelf northward flow on shelf • Concentrate reservoir drawdown in a few high-flow Concentrate reservoir drawdown in a few high-flow

periods, to flush SPM and Feperiods, to flush SPM and Fe

ReferencesReferences

►Hutchins, D.A., G.R. DiTullio, Y. Zhang, and K.W. Bruland, An iron limitation mosaic in the California upwelling regime, Limnol. Oceanogr., 43, 1037-1054, 1998.

►Johnson, K.S., F.P. Chavez, and G.E. Friederich, Continental-shelf sediment as a primary source of iron for coastal phytoplankton, Nature, 398, 697-700, 1999.

►Chase, Z., A. van Geen, P.M. Kosro, J. Marra, P.A. Wheeler, 2002. Iron, nutrient and phytoplankton distributions in Oregon coastal waters. Journal of Geophysical Research, Oceans. ?? Volume, page??

Fe in the CR Plume Area Fe in the CR Plume Area (Conceptual) --(Conceptual) --• WA productivity generally higher, winter Fe input??WA productivity generally higher, winter Fe input??• Plume moves south and offshore during upwellingPlume moves south and offshore during upwelling• Fe from river, BBL and from plume frontal mixingFe from river, BBL and from plume frontal mixing

Nonlinear multivariate least-squares regression, with seasonal Nonlinear multivariate least-squares regression, with seasonal variability:variability:

Rating curve approach (Crawford, 1991):Rating curve approach (Crawford, 1991):F = function(Q,T); Q is flow; T is decimal year multiplied by 2F = function(Q,T); Q is flow; T is decimal year multiplied by 2F = exp [ kF = exp [ k11 + k + k22*ln(Q) + k*ln(Q) + k33*sin(T) + k*sin(T) + k44*cos(T) + k*cos(T) + k55*T ]*T ]Problems:Problems:

1. handling of “below detection” data1. handling of “below detection” data2. short data set (1992-date) and secular change2. short data set (1992-date) and secular change3. CR landward of Portland has low dFe levels3. CR landward of Portland has low dFe levels

US GS dFe Hydrologic Model for Beaver US GS dFe Hydrologic Model for Beaver ----

Historic Changes in Columbia Historic Changes in Columbia FlowFlow

• CR virgin flow is CR virgin flow is estimated from resevoir estimated from resevoir and agricultural and agricultural withdrawalswithdrawals

• WR virgin flow is not WR virgin flow is not known, thus the winter known, thus the winter flow shown is likely much flow shown is likely much lowerlower

• Climate change Climate change responsible for most of responsible for most of the freshet timing changethe freshet timing change

• however, 1880 was an however, 1880 was an unusually cool PDO- yearunusually cool PDO- year

• Role of marshes and tidal flats unclearRole of marshes and tidal flats unclear• lower CR marshes have been diked (75% loss)lower CR marshes have been diked (75% loss)• estuary tidal flat area has increased slightly estuary tidal flat area has increased slightly

(which is more important to dFe?)(which is more important to dFe?)