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