Publications

Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized as terrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were...

It is widely recognized that wetlands, especially those rich in organic matter and receiving appreciable atmospheric mercury (Hg) inputs, are important sites of methylmercury (MeHg) production. Extensive wetlands in the southeastern United States have many ecosystem attributes ideal for promoting high MeHg production rates; however, relatively few mercury cycling studies have been...

Compliance with U.S. air quality regulatory standards for atmospheric fine particulate matter (PM2.5) is based on meeting average 24 hour (35 μ m−3) and yearly (15 μg m−3) mass‐per‐unit‐volume limits, regardless of PM2.5 composition. Whereas this presents a workable regulatory framework, information on particle composition is needed to assess the fate and transport of PM2.5 and determine...

Phylogenetic analysis indicates that microbial arsenic metabolism is ancient and probably extends back to the primordial Earth. In microbial biofilms growing on the rock surfaces of anoxic brine pools fed by hot springs containing arsenite and sulfide at high concentrations, we discovered light-dependent oxidation of arsenite [As(III)] to arsenate [As(V)] occurring under anoxic...

The vulnerability of a municipal well in the Northwest well field in southeastern Florida to potential contamination by Cryptosporidium parvum oocysts was assessed in a large‐scale, forced‐gradient (convergent) injection and recovery test. The field study involved a simultaneous pulse introduction of a nonreactive tracer (SF6, an inert gas) and oocyst‐sized (1.6, 2.9, and 4.9 μm diameter...

Quantifying biogeochemical cycles of nitrogen (N) and the associated fluxes to surface waters remains challenging, given the need to deal with spatial and temporal variability and to characterize complex and heterogeneous landscapes. We focused our study on catchments S14 and S15 located in the Adirondack Mountains of New York, USA, which have similar topographic and hydrologic...

As part of the continuing effort to collect baseline information on the environmental occurrence of pharmaceuticals, and other organic wastewater contaminants (OWCs) in the Nation's water resources, water samples were collected from a network of 47 groundwater sites across 18 states in 2000. All samples collected were analyzed for 65 OWCs representing a wide variety of uses and origins...

The Massachusetts Military Reservation (MMR) has been a military base on western Cape Cod since the early 1900s. Contaminated surface water and ground water from the MMR have discharged into several kettle lakes on or near the base. To discover whether the prevalences of tumors and other lesions in brown bullhead (Ameiurus nebulosus) in these lakes, particularly Ashumet Pond, were...

Understanding how changes in land use affect water quality of public supply wells (PSW) is important because of the strong influence of land use on water quality, the rapid pace at which changes in land use are occurring in some parts of the world, and the large contribution of groundwater to the global water supply. In this study, groundwater flow models incorporating particle tracking...

Historical weapons testing and disposal activities at Camp Edwards, which is located on the Massachusetts Military Reservation, western Cape Cod, have resulted in the release of contaminants into an underlying sand and gravel aquifer that is the sole source of potable water to surrounding communities. Ground-water models have been used at the site to simulate advective transport in the...

Atmospheric mercury (Hg) is delivered to ecosystems via rain, snow, cloud/fog, and dry deposition. The importance of snow, especially snow that has passed through the forest canopy (throughfall), in delivering Hg to terrestrial ecosystems has received little attention in the literature. The snowpack is a dynamic system that links atmospheric deposition and ecosystem cycling through...

Aquifer susceptibility to contamination is controlled in part by the inherent hydrogeologic properties of the vadose zone, which includes preferential-flow pathways. The purpose of this study was to investigate the importance of seasonal ponding near leaky irrigation wells as a mechanism for depression-focused preferential flow and enhanced chemical migration through the vadose zone of...