Environmental Health - Toxic Substances Hydrology Program

Toxic Substances Hydrology Program Investigations

The U.S. Geological Survey (USGS) Toxic Substances Hydrology Program has investigations focused on issues of national concern including contaminants associated with energy production, resource extraction, harmful algal blooms, home and personal-care product use and disposal, and agricultural production.

Graph, sampling depth in meters on left, oxygen concentration in micromoles per kilogram on right.
The location of the maximum methylmercury concentration at depth in the Pacific Ocean was the first evidence noted by the researchers pointing to the new methylation cycle. The graphic shows sampling depth on the left (in meters), and oxygen concentration on the right (in micromoles per kilogram of seawater [µmol/kg]) along a north-south latitudinal transect in the eastern North Pacific Ocean. The specific depth of maximal methylmercury concentration was consistently found at the ocean depth where the most rapid loss of oxygen was also observed. The process linking these two observations is microbial decomposition of "ocean rain", which is settling algae produced near the surface of the ocean. The decomposition process consumes oxygen from the water, but also leads to unintended methylmercury production -- from the Mercury in Aquatic Ecosystems Investigation
USGS scientist collecting water samples and measuring water field properties

Chemical Mixtures and Environmental Effects

The USGS is providing the science to understand the occurrence and the potential effects of complex mixtures of both natural and anthropogenic chemicals in environmental waters.

USGS scientist with equipment used to inject fluids for a bioaugmentation experiment

Chlorinated Solvents in Fractured-Rock Aquifers

The USGS is providing the science to understand the hydrological, geochemical, and microbiological processes controlling contaminant fate in fractured-rock aquifers.

Four sample bottels filled with leachate

Contaminants of Emerging Concern in the Environment

The USGS is providing the science to understand the sources, fate, exposure, and potential effects of a broad range of chemical and microbial contaminants that we use in our everyday lives.

USGS scientists collecting a water sample from a well at the USGS Bemidji Research Site

Crude Oil Contamination in the Shallow Subsurface

The USGS is providing the science to understand the long-term persistence and natural attenuation of petroleum hydrocarbon spills in soils and groundwater.

USGS scientist lifting a sample bottle from ice hole

Fate and Effects of Wastes from Oil and Gas Development

The USGS is providing the science to assess the environmental health risks associated with wastes from oil and gas development by characterizing waste materials, identifying potential environmental pathways, and evaluating the potential effects on organisms from exposure to unintended waste releases.

USGS scientists collecting gas samples from the unsaturated zone

Low-Level Radioactive and Mixed- Hazardous Wastes

The USGS is providing the science to understand of processes controlling the migration and fate of contaminants in arid environments.


Mercury in Aquatic Ecosystems

The USGS is providing the science to understand mercury sources, pathways, and key processes in the environment, with particular emphasis on understanding mercury methylation and accumulation in aquatic ecosystems.

USGS scientist collecting a water-quality sample from Zollner Creek, Oregon

Pesticide Contamination and Environmental Exposure

The USGS is developing methods to measure new pesticides and their byproducts in environmental media, conducting studies on the fate of these chemicals, assessing exposure to understand potential effects on fish, wildlife, and human health.

Fish in flow-through containers sitting in a small stream.
Fish held in flow-through containers are exposed to metal concentrations with daily high and low cycles (diel cycles). Scientists conducted a field experiment to compare survival of newly hatched trout (fry) exposed to constant versus varying metal concentrations, High Ore Creek, Montana The experiment will help scientists understand the effect of diel variations in the concentration of metals on fish in mining affected areas -- from the Watershed Contamination from Metal and Uranium Mining Investigation
White tanks used to hold the tracer injection solutions with tubing going to injection wells

Sewage-Contaminated Groundwater

The USGS is providing the science to understand the potential health risks of contaminants from wastewater plumes and spills that have persisted for decades in shallow groundwater.

View of Cement Creek, a mining impacted stream in Colorado

Watershed Contamination from Metal and Uranium Mining

The USGS is providing information and tools to support decisions related to management, risk assessment, remediation planning, and mitigation of the effects of hard-rock metal mining and uranium mining on watersheds and ecosystems.


Archive of Completed and Past Investigations


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Page Last Modified: 16-Jun-2017 @ 03:56:44 PM EDT