Long Island Sound has suffered from hypoxia for decades:

•Result of Global Warming?

•Eutrophication?

•It has always been like this…...

EAST LIS

CENTRAL LISWEST LIS

NARROWS

Sampling mud

Design “proxies” for paleo- environmental research such as•Salinity•Temperature•Faunal/floral characteristics•Oxygen saturation•Metals•SewageCalibrate proxies for these parameters on the modern LIS environment

Ages of core samples:

• 137Cs, 210Pb

• Pollen records(Europeansettlement,chestnut blight)

• Metal pollution(dated in marshcores by 210Pb)

5004003002001000

1600

1650

1700

1750

1800

1850

1900

1950

2000

Hg ppb

years AD, core A1C1

Ragweed pollen

Onset of hattingindustry

Chestnut blight

137Cs

210Pb

14C

MAY 04 CALIB ON MARINE DATA CORE A1C1

y = -0.0064x3 + 0.148x2 - 6.0776x + 2006.6R2 = 0.9971

800

1000

1200

1400

1600

1800

2000

0 10 20 30 40 50 60

DEPTH CM

AGE ANCHORSPoly. (AGE ANCHORS)

14C

14CHG

137CS

MEASURES OF ORGANIC PRODUCTIVITY:

•BURIAL RATE OF ORGANIC CARBON

•BURIAL RATE OF DIATOM “SKELETONS” (BIOGENIC SILICA)

•PRODUCTION RATE OF HETEROTROPHS LIKE FORAMINIFERA

Co

rg,

%

0

2

4

6

8

10

12

14

16

18

20

900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Age years AD

BSiCorg

0

1

2

3

4

5

6

7

900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Age years AD

Carbonate*10, Ca %

carb*10Ca %

Elphidium excavatum

QuickTime™ and aNone decompressor

are needed to see this picture.

The 13C values in foram “shells” are related to mixing of sea and

river water (salinity) and to addition of “light carbon” from

photosynthetic productivity

Estimate 13C variability not related to mixing of sea and river water (13C*)

• Measure 18O values in foraminiferal shells• Calculate 18O of water using BWT • Estimate salinity from LIS mixing model • Estimate 13C of dissolved inorganic carbonate

using the LIS mixing model• Subtract calculated - observed values:

13C * = 13Ccarbonate - 13Ccalculated in water

-3.50

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

-73.80 -73.30 -72.80 -72.30

Longitude

d13C* per mille

1996/1997

1961 Buzas

Linear(1996/1997)Linear (1961Buzas)

New York

New London

-5.0

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Age cal years AD

d13C*, per mille

-2.5

-2.0

-1.5

-1.0

-0.5

0.01350 1450 1550 1650 1750 1850 1950

Age Years AD

per mille

A4C1

d13C*

Core data

% organic Carbon and 13C*

2000180016001400120010008001.0

1.4

1.8

2.2

2.6

Corg %

Corg %

200018001600140012001000800-5

-4

-3

-2

-1

0d13C*

d13C*

Year AD

CORE A1C1

The 13C* value indicates the amount of oxidized Corg that was added to the bottom water column.

The 13C* value serves as an indirect proxy for OCI or Oxygen Consumption Index (Level of

Paleo Oxygenation)

0

20

40

60

80

100

120

140

160

900 1100 1300 1500 1700 1900

Age Years AD

Core A1C1rel T

Age years AD

0

200

400

600

800

1000

1200

1400

1600

900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

C. perfringens, #/gr sediment

Cperf

0

50

100

150

200

250

300

350

400

450

500

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Age years AD

Metals ppm

CrCuHgPb

CONCLUSIONS (1)

•Major environmental changes in the early 1800’s:• Increased Corg and Bsi storage

• Isotopically lighter carbon, lower O2 levels in bottom waters, sewage indicators, and metal pollutants

• Increased productivity of benthic foraminifera

CONCLUSIONS (2)

• Hypoxic events may have occurred since the early 1800’s but were absent before that time. They are severe in the late 20th century. Why? – Enhanced productivityEnhanced productivity==> more Corg

– Modern global warming==> higher rate of Corg decompositon and increased water stratification

HYPOXIAHYPOXIA NEED A COMBINATION OF HIGH BWT AND HIGH Corg LOADING