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Determination of Recent Inputs of Mercury to Lakes/Ponds in the Merrimack
Valley Using Sediment Cores - A Feasibility Study
FINAL REPORT PREPARED FOR Office Of Research And Standards
Massachusetts Department Of Environmental Protection
By Gordon T. Wallace
Sarah Oktay
Franco Pala
Melissa Ferraro
Melissa Gnatek
Darryl Luce Department Of Environmental, Coastal And Ocean Sciences
University Of Massachusetts At Boston
100 Morrissey Boulevard
Boston, Massachusetts, 02125 And Michael Hutcheson
Jane Rose Office Of Research And Standards
Massachusetts Department Of Environmental Protection
MARCH 2004 TABLE OF CONTENTS ABSTRACT IV
1.0 INTRODUCTION 1
2.0 METHODS 4
2.1 SAMPLE COLLECTION 4
2.2 SAMPLE PROCESSING 5
2.3 RADIOISOTOPES 6
2.4 METALS 6
3.0 RESULTS AND DISCUSSION 7
3.1 GEOCHRONOLOGY 7
3.2 GENERAL CORE PROPERTIES 7
3.3 SEDIMENT MERCURY PROFILE 8
3.4 MERCURY FLUX 9
3.5 SUPPORTING METAL DATA 10
4.0 CONCLUSIONS 11
5.0 REFERENCES 13
APPENDIX I AND II
LIST OF TABLES TABLE 1. SAMPLING LOCATIONS, WATER DEPTH AND CORE LENGTHS FOR CORES TAKEN
ON MAY 2, 2001 15
Table 2. Radioisotoope Data for Lake Cochichewick Core 15
Table 3. Organic Carbon and Nitrogen Profiles for Lake Cochichewick Core.
16
Table 4. Lake Cochichewick Core Metal Profiles. 17
Table 5. Mercury Accumulation Rates in Lake Cochichewick Core. 18
LIST OF FIGURES FIGURE 1. MAP OF LAKE COCHICHEWICK AND SURROUNDING KAMES, 1880, BY GEORGE
F. WRIGHT, FROM HISTORIC SKETCHES OF ANDOVER BY SARAH LORING BAILEY,
1880. 19
Figure 2. Turn-of-the-century photograph showing the expansion of Lake
Cochichewick to increase reservoir capacity. From the North Andover
Historical Society. 20
Figure 3. Aerial view of Lake Cochichewick with municipal waste
incinerator in background. 20
Figure 4. Topographic map showing the location of the two core samples
taken in Lake Cochichewick. 21
Figure 5. Total 210Pb plotted against depth and cumulative mass over
entire length of core. Supported 210Pb activity (0.0604 Bq/g dry
weight) is shown for reference. 22
Figure 6. Plot of the data and regression curve for the portion of the
core used to establish 210Pb geochronology. The range indicated by the
points represents about 100 years of sediment accumulation to a depth of
12 cm. 23
Figure 7. 137Cs profile shown as a function of cumulative mass and date as
determined from 210Pb geochronology. Note the date of the maximum in
137Cs is close to 1963, the time of maximum release of 137Cs into the
atmosphere by nuclear testing. 24
Figure 8. Fraction dry weight (?) and organic carbon (?) profiles for the
Lake Cochichewick core. 25
Figure 9. Mercury concentration profile for the Lake Cochichewick Core.
Mercury concentrations become elevated over background well before 1900
but the rate of change dramatically increases after that time. 26
Figure 10. Plot of mercury concentrations as a function of cumulative mass
and date as determined from 210Pb geochronology. Note the absence of
any decrease in mercury concentration over the last decade. 27
Figure 11. Mercury fluxes into sediments of Lake Cochichewick over the last
120 years. Panel on right indicates estimated change in sediment flux
for each dated core section. 28
Figure 12. Comparison of sediment mercury concentrations in dated cores
from Echo Lake and Lake Cochichewick. 29
Figure 16. Zinc profile over the entire length of the Lake Cochichewick
core. 31
Figure 17. Copper profile over the entire length of the Lake Cochichewick
core. 32
Figure 18. Arsenic profile over the entire length of the Lake Cochichewick
core. 32
Figure 19. Tin profile over the entire length of the Lake Cochichewick
core. 33
Figure 20. Aluminum profile over the entire length of the Lake
Cochichewick core. 33
Figure 21. Iron profile over the entire length of the Lake Cochichewick
core. 34
Figure 22. Fe:Al ratio profile over the entire length of the Lake
Cochichewick core. Value in ( ) an outlier. 34
ABSTRACT THE OBJECTIVE OF THIS STUDY WAS TO DETERMINE THE FEASIBILITY OF USING
ISOTOPE GEOCHRONOLOGICAL TECHNIQUES TO ESTABLISH THE RECENT HISTORY OF
MERCURY ADDITIONS TO A LAKE IN A REGION OF THE COMMONWEALTH OF
MASSACHUSETTS PREDICTED TO HAVE REGIONALLY HIGH MERCURY DEPOSITION AND
DOCUMENTED TO HAVE HIGH FISH TISSUE MERCURY CONCENTRATIONS. A SEDIMENT
CORE WAS OBTAINED BY BOX CORER FROM LAKE COCHICHEWICK IN NORTH ANDOVER, MA.
THIS GLACIAL LAKE OF APPROXIMATELY 600 ACRES WAS KNOWN TO HAVE RELATIVELY
HIGH CONCENTRATIONS OF MERCURY IN THE EDIBLE TISSUES OF THE FISH AND IS
ALSO LOCATED IN RELATIVELY CLOSE PROXIMITY TO SEVERAL COMMERCIAL WASTE
COMBUSTION FACILITIES. Historical mercury deposition was determined using mass accumulation rates
determined by isotope geochronology and mercury concentrations down the
length of the core. Cores were sectioned and analyzed at 1 cm intervals.
Radioactivity counts for 210Pb and 137Cs were performed for each core
section. Total mercury, lead, cadmium, zinc, copper, arsenic, tin,
aluminum and iron concentrations were determined in each core section.
Mercury deposition rates versus depth and date were determined. Mercury inputs to the lake started to increase in comparison to the rates
from another rural lake without obvious local mercury sources in
Massachusetts towards the end of World War I (1918). Rates continued to
accelerate through the twentieth century with most recent rates approaching
90 ug/m2/yr: consistent with model predicted atmospheric deposition rate
for mercury in the study area. The pre-Industrial Revolution mercury
deposition rate to the lake was around 13 ug/m2/yr. The highest increase
in mercury deposition rate between core sections was for the period between
1990 and 1996, shortly after the construction of the incinerators in the
1980s near Lake Cochichewick. Whether this jump in Hg flux was wholly in
response to the emissions from these incinerators cannot be conclusively
defined by the limited data here but does argue for closer scrutiny of the
importance of these and possibly other local and regional sources.
Ancillary metals deposition chronologies generally supported the picture
for mercury along with providing expected temporal markers in the core of
known events specific to some metals (e.g., deleading gasoline).
1.0 Introduction ANTHROPOGENIC MOBILIZATION OF MERCURY ON A GLOBAL BASIS HAS DRAMATICALLY
ALTERED THE NATURAL CYCLING OF THIS METAL AND GREATLY ENHANCED FLUXES AND
CONCENTRATIONS OF THIS METAL IN THE ECOSYSTEM. BECAUSE OF THE WELL-KNOWN
IMPACT OF MERCURY ON HUMAN HEALTH AND THE ENHANCED EXPOSURE TO THIS METAL
RESULTING FROM ANTHROPOGENIC MOBILIZATION, THERE IS A NEED TO BETTER
UNDERSTAND THE PHYSICAL, CHEMICAL, AND BIOLOGICAL PROCESSES AFFECTING THE
SPECIATION, CONCENTRATION, TRANSPORT AND FATE OF MERCURY IN THE
ENVIRONMENT. MERCURY CONTAMINATION IN THE STATE OF MASSACHUSETTS HAS
RESULTED IN UNACCEPTABLE LEVELS OF MERCURY (AS METHYLMERCURY) IN SOME
SPECIES OF EDIBLE FRESHWATER AND COASTAL FISH AND SHELLFISH RESULTING IN
PUBLIC WARNINGS TO SENSITIVE SEGMENTS OF THE PUBLIC REGARDING THE INGESTION
OF THESE FOODS (ROSE ET AL., 1999, WALLACE ET AL., 1988). Factors leading to the production and accumulation of mercury in edible
fish, primarily as methylmercury, are not well understood. Currently there
is an inability to explain the significant variability in concentration of
total mercury, mostly of which is present as methylmercury, in fish of the
same species collected from different waterbodies, even within a regional
context in the state. One of the impediments inhibiting our ability to
explain mercury body burdens is the less than complete knowledge of the
processes that control the production and bioavailability of methylmercury
in the environment. Until these processes are better understood,
explanation and prediction of body burdens in edible fish will remain an
elusive target. The production of methyl mercury in the environment has and continues to be
extensively studied. Both abiotic and biological mechanisms have been
identified as potential sources of organomercury although most agree that
microbiological processes are most prevalent. Formation of methylmercury
is a detoxification mechanism used by bacteria to ameliorate the effects of
mercury (ultimately dependent on its free metal ion activity) to which the
organisms are exposed. Direct effects of inorganic mercury are rare as the
mediating affect of dissolved and colloidal organic matter and sulfide and