Chemical and Biological Control of Mercury Cycling in Upland, Wetland and Lake Ecosystems in the Northeastern U.S.

EPA Grant Number: R827633
Title: Chemical and Biological Control of Mercury Cycling in Upland, Wetland and Lake Ecosystems in the Northeastern U.S.
Investigators: Driscoll, Charles T. , Munson, Ronald , Newton, Robert , Yavitt, Joseph
Institution: Syracuse University , Cornell University , Smith College , Tetra Tech Inc.
EPA Project Officer: Hiscock, Michael
Project Period: November 1, 1999 through October 31, 2002 (Extended to October 31, 2003)
Project Amount: $786,680
RFA: Mercury: Transport and Fate through a Watershed (1999) RFA Text |  Recipients Lists
Research Category: Water and Watersheds , Mercury , Water , Safer Chemicals

Description:

Widespread contamination of mercury in remote aquatic environments due to atmospheric deposition, and consequent high concentrations in the biota, demand an improved understanding of the mechanisms of mercury transformations and cycling in lake/watershed ecosystems. Previous studies have reported elevated concentrations of mercury in the water column and in fish in lakes in the Adirondack region of New York. Concentrations of mercury in fish tissue have been shown to increase with decreasing pH, suggesting a link between mercury accumulation and surface water acidification. Lakes which receive drainage from wetlands are characterized by high concentration of methyl mercury because of elevated rates of methylation that occur in these environments but low bioconcentration of mercury in fish due to the supply of dissolved organic carbon which decreases the bioavailability of methyl mercury. Recent paleolimnological studies have shown marked (3.5x) increases in sediment mercury deposition since 1850, suggesting that increases in atmospheric mercury deposition have contributed to the regional contamination of mercury. Moreover, these studies suggest that watershed retention of mercury has decreased markedly over the last 60 years, from 95% retention of atmospheric mercury deposition in the 1930s to 75% retention today. As a result there is an acute need to clarify the chemical and biological processes regulating the transport, fate and bioavailability of mercury in soft-water lake/watersheds of the northeastern U.S., and to develop and apply a simulation model to depict these processes.

Objectives:
The specific objectives of this proposed research are:

Objective 1. To quantify patterns of transport and transformations of mercury species in an upland northern hardwood forest through adjacent wetlands to the aquatic environment.
Objective 2. To evaluate the processes and mechanisms controlling methyl mercury concentrations and transport in pore water and surface water in wetlands.
Objective 3. To evaluate historical patterns of mercury dynamics in soft-water lakes.
Objective 4. To develop and apply a lake/watershed mercury cycling model to a lake/watershed ecosystem.

Approach:

Specifically, this project will examine: 1) the transport of mercury and interactions with organic matter and metals in upland soil, wetlands and surface waters; 2) rates and controls of methylation and demethylation of Hg in organic matter-rich wetland environments; and 3) factors which influence historical changes in the deposition of mercury to lake sediments. A combination of field watershed measurements and controlled experiments will be employed to quantify mercury behavior in a typical glaciated landscape in the Adirondack region of New York. Patterns of concentration of mercury species in soil water, porewater of wetlands, stream waters and lake sediments will be examined in concert with studies of mercury emissions, and transformations. Field and controlled laboratory studies will examine biological and physical-chemical factors regulating net methylation of mercury and factors which influence the binding of mercury to naturally occurring organic solutes. As part of this study, a watershed-wetland-lake mercury cycling model will be developed and applied to the study site. These mechanistic studies will provide a greatly improved basis for process formulations and parameter values for the mercury-cycling model. This proposed research will do done in conjunction with a funded study to investigate mercury cycling in an Adirondack lake ecosystem and mercury accumulation in fish. The proposed study will provide critical information on watershed processes controlling the chemistry and transport of mercury to a downstream lake.

Expected Results:

The 1990 Amendments of the Clean Air Act require that the United States Environmental Protection Agency (USEPA) evaluate the effects of atmospheric emission of mercury. This proposed study will provide critical information to the USEPA and agencies in northeastern U.S. concerned with the consequences of elevated atmospheric mercury deposition. Much of the northeastern U.S. is a complex mosaic of upland forests, wetlands and surface waters. While atmospheric mercury deposition entering forest watersheds undergoes transformations altering the speciation and bioavailability of mercury prior to entering aquatic ecosystems, little is known about these processes. To our knowledge there has not been a detailed study of mercury biogoechemistry in a temperate lake/watershed ecosystem. As part of this proposed study a comprehensive watershed mercury cycling model will be developed and calibrated. This model could be used in regional assessments of the effects of atmospheric mercury deposition on watershed/lake ecosystems.

Publications and Presentations:

Publications have been submitted on this project: View all 28 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

acidic deposition, beaver impoundments, organic matter., RFA, Scientific Discipline, Geographic Area, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Hydrology, Contaminated Sediments, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Chemistry, State, Fate & Transport, Ecological Effects - Environmental Exposure & Risk, Air Deposition, Mercury, aquatic, fate and transport, ecological exposure, forested watersheds, wetland ecosystem, contaminated sediment, upland ecosystems, surface water, mercury cycling, dissolved organic carbon, watershed influences, mercury cycle, water acidification, Clean Air Act, lake sediment, wetland, lake ecosystem, atmospheric deposition, heavy metals, lake ecosystems

Relevant Websites:

Synthesis Report of Research from EPA’s Science to Achieve Results (STAR) Grant Program: Mercury Transport and Fate Through a Watershed (PDF) (42 pp, 760 K)

Progress and Final Reports:

  • 2000 Progress Report
  • 2001 Progress Report
  • 2002
  • Final Report