RESEARCH

Recently he has been investigating atmospheric inputs of persistent organic chemicals and mercury to Lake Ontario, the atmospheric deposition and emission of mercury from forested ecosystems, and investigating the transport, deposition and sources of pollutants in New York State.

 

 

This project will provide estimates of loadings of a number of critical pollutants identified in the Lake Ontario LaMP as well as several additional chemicals. Sources of these pollutants will also be identified using advanced source-receptor models.  The sampling proposed includes the collection of ambient air samples of Hg (both elemental and reactive gaseous),

 

PCBs, DDE, Mirex, HCB and Dioxin/Furans every six days for a period of approximately one year at Sterling, NY on the shoreline of Lake Ontario.  Wet deposition samples of Hg, PCBs, DDE, Mirex, HCB and Dioxin/Furans and direct dry deposition samples for PCBs, DDE, Mirex, HCB will also be collected at the same location.  Samples will also be collected for 1 week each in spring and

summer aboard the Lake Guardian.  During each week on the ship, coupled air and water concentrations will be measured and several wet and dry deposition samples will be obtained.  During sampling on the ship, intensive daily samples will also be obtained at the land-based site.  The work outlined in this proposal will supplement the ongoing monitoring supported by Environment Canada at Point Petre, Ontario (one of the Great Lakes International Atmospheric Deposition Network (IADN) sites) and the Mercury Deposition Network (MDN).

The objectives of this project are to develop a database of ambient atmospheric measurements and apply appropriate receptor models to those data to permit us to determine the contributions of electricity generation to the observed concentrations of nitrate, sulfate, Hg⁰, reactive gases mercury (RGM) and fine airborne particulate matter.  Furthermore, we will separate the contributions of in-state and out-of-state emissions with an emphasis on transboundary sources.  Initially this work focused on daily summer samples, but as of September 2001, it changed to the sampling and analysis of samples every third day throughout the year.

Widespread contamination of mercury in remote aquatic environments due to atmospheric deposition and consequent high concentrations in aquatic biota, suggest that there is an acute need to improve understanding of the mechanisms of mercury transport and transformations in lake/watershed ecosystems.  Atmospheric deposition of mercury to forest ecosystems is enhanced by processes within the canopy. Mercury entering the forest floor largely via throughfall and litterfall may be a factor of two or more greater than wet deposition. Following deposition, mercury undergoes a series of complex pathways and transformations, which interconnect with other element cycles, and ultimately control the supply of methyl mercury to aquatic biota. Important, but poorly understood mechanisms of Hg transport and transformations include: mineralization of litter mercury inputs, binding of mercury and methyl mercury in forest soils, wetlands and sediments, conversion of ionic mercury to methyl mercury and/or volatile elemental mercury, and the bioavailability of methyl mercury to aquatic biota.

The specific objectives of this proposed Biocomplexity study are to: Objective 1: To quantify the inputs, transformations and losses of mercury species in an upland northern hardwood forest. Objective 2: To determine conditions controlling the complexation, immobilization and net methylation of mercury. Objective 3:  To assess the fate, transport and bioavailability of atmospheric mercury deposition across the Adirondack landscape.

 

 

 

 

 

 

 

 

 

 

 

To accomplish our research objectives and test hypotheses, we propose an integrated program of field and laboratory research. We will conduct detailed plot-level field studies examining pathways of mercury deposition to the forest floor, and the subsequent transport and fate of atmospherically deposited mercury (Objective 1). These studies will be conducted at the Huntington Forest, in Newcomb, NY. We will instrument a previously studied plot and conduct detailed measurements of mercury exchange with the forest floor. We will investigate binding of ionic mercury and methyl mercury with dissolved and soil organic matter in laboratory experiments (Objective 2). Biotic controls on methylation/demethylation will also be evaluated in the laboratory under a range of terminal electron acceptors, and molecular techniques will be used to identify communities of methylating bacteria.   To investigate how well our understanding of mercury dynamics can be applied across the Adirondacks, we will conduct field measurements of atmospheric deposition, soil Hg species, and Hg species in lake water and aquatic biota in eight watersheds (Objective 3).  The water column and sediment mercury deposition have been previously been studied in the lakes of these eight watersheds.  We will supplement these observations with a comprehensive sampling of the biotic assemblages.  The process-oriented Mercury in Adirondack Wetlands Lakes and Terrestrial Systems model will be a critical tool in this Biocomplexity project. Results from the field plot study and the laboratory studies will be used to improve formulations of important processes affecting mercury deposition, fate, transport, transformations and bioavailability in northern forest ecosystems.

 

  With the recent evidence linking airborne particulate matter (PM) to adverse health effects (Dockery et al., 1993), and findings that deposition of pollutants associated with PM are significant inputs to many ecosystems (Landis and Keeler, 2002), there is an urgent need for techniques that can measure PM and pollutants associated with PM at short enough time scales that sources of these particles can be characterized and mechanistic models of their chemistry and fate developed. Since health effects and deposition are dependent on particle size, these techniques should also be able to separate the PM by size before they are characterized. An additional requirement of these instruments is that they separate particles from gas stream before collection to avoid sampling artifacts (the inadvertent inclusion of gas in particle measurements or the vaporization of particle before measurement).

 

The central objective of this project is to design and evaluate an innovative sampler, Wide-Range Impactor Particle sampler for composition analysis (WRIPS), that can be routinely used to sample and analyze specific components of size-segregated atmospheric particles without artifacts.

Outline of project

1)CFD modeling

Commercial CFD software FLUENT (Fluent Inc, MA) was used to calculate and optimize the design of the WRIPS before it is built. CFD software can simulate all type of environments such as heat, mass, wind speed and direction, and so on for WRIPS. Based on these, WRIPS design parameters for instant, Counterflow virtual Impactor, new inlet, and pump requirements etc., will be optimized.

 

 

 

2)Wind tunnel test

Characterize WRIPS in controlled condition. This approach would inject particles towards the sampler (i.e. along the flow) using a thin walled injector. This technique will results in a high concentration of particles in a narrow range of streamlines at the test location. The injector will be then be translated along the height and breadth of the wind tunnel over the collection time of the sampler. This will result in a time averaged spatially uniform particle seeding for the sampler testing. The concentration profile at the test location will be experimentally investigated by collection of a filter cassette.