The U.S. Geological Survey (USGS)Toxic Substances Hydrology (Toxics)Program provides unbiased scientificinformation on the behavior of toxicsubstances in the Nation’s hydrologicenvironments. Program contributionsimprove contaminated-site managementand remediation, and enable informeddecisions by industry, management andregulatory agencies, and the public.

The objectives of Program activities areto:

• Develop methods to measurecontaminants and their degradationproducts at levels low enough tocharacterize environmental transport andfate;

• Quantify the physical, chemical, andbiological processes that affectcontaminant migration, transformation,and degradation in the environment;

• Understand the ultimate fate ofcontaminants in hydrologic systems andthe potential long-term implications forhuman and environmental health;

• Describe the effects of contaminants onorganisms, ecosystems, and the foodchain; and

• Develop simulation models to assesspotential exposure to contaminants andto design waste-disposal facilities,monitoring networks, and remediationstrategies.

Investigations of representative types ofenvironmental contamination are beingconducted across the Nation and focus on:

Point-source subsurfacecontamination, and

Watershed- and regional-scalecontamination.

USGS Toxic Substances Hydrology Program, 2000The Toxics Program coordinates withfederal land-management, regulatory, andscience agencies to ensure that current andfuture science needs are being met. TheProgram complements the water-qualitymonitoring and assessment programs ofthe USGS, states, and others byidentifying new issues and emergingcontaminants, and by developing theknowledge and methods needed to meetfuture monitoring needs. Scientists fromuniversities, other federal agencies, andindustry actively participate in theProgram’s activities.

Investigations of Point-SourceSubsurface Contamination

Point-source subsurface investigations areconducted at sites representative ofcommon contamination problems andgeohydrologic settings. Theseinvestigations are long-term, field-basedstudies conducted by interdisciplinaryresearch teams.

Comprehensive physical, chemical, andmicrobial characterizations of the sitesestablish field-laboratory conditions thatprovide fundamental knowledge of theprocesses that control specific types ofcontamination problems. This fundamentalprocess knowledge is generalized to awide range of field conditions by specificfield and laboratory experiments at othersites with varied conditions and properties.The resulting knowledge and methodsimprove the effectiveness of and reducethe cost of characterization andremediation at contaminated sites acrossthe Nation.

A unifying theme of these investigations ischaracterization of the natural response ofhydrologic systems to contamination. Thismakes them ideally suited for assessingpotential long-term impacts, evaluating thepotential and limitations of remediation bynatural attenuation, and designingremediation-performance monitoring.

TOXICS PROGRAM STUDY SITES

Bemidji, MN(Crude Oil)

The Mid-ContinentCornbelt

(Pesticides)

Pinal Creek,AZ (Mining)

Upper ArkansasRiver Watershed

(Mining)

San FranciscoBay-Estuary(Pesticides,

Metals)

Mirror Lake, NH(Fractured Rock)

Cape Cod, MA (Sewage)

Galloway, NJ(Gasoline)

Picatinny Arsenal, NJ

(TCE)

Norman, OK(Landfill)

Southern Cotton Agriculture(Pesticides)

Upper Animas River Watershed (Mining)

Boulder River Watershed (Mining)

Amargosa Desert(Radionuclides, Mixed Wastes)

Laurel Bay, SC(Oxygenated

Gasoline)

NATIONAL INVESTIGATIONSAmphibian Research and Monitoring Initiative Mercury Contamination in Aquatic EcosystemsEmerging Contaminants in Streams and Wells

Point-source SubsurfaceInvestigations

Watershed- and Regional-Scale Investigations

U.S. Department of the InteriorU.S. Geological Survey

USGS Fact Sheet FS-062-00May 2000

Point-source subsurface investigationsinclude:

• Ground-Water Flow and Transport inFractured Rock - Mirror Lake, NewHampshire. Research develops methodsfor defining the movement of water andcontaminants in fractured-rock aquifers.Contaminant transport and fate isfundamentally different in fractured rockthan in unconsolidated (sand and gravel)aquifers. In many cases, remedial actionis delayed or stymied by the complexityof these problems.

• Landfill Leachate - NormanMunicipal Landfill, Norman,Oklahoma. Leachate from thousands ofactive and closed landfills across theNation may pose a threat to groundwater and its receiving waters. Thisresearch is defining the biogeochemicalcontrols on the migration and fate of thecomplex mixture of chemicals found inlandfill leachate.

• Subsurface Contamination byChlorinated Solvents - PicatinnyArsenal, New Jersey. Knowledgegained from this research of the physical,chemical, and biological processes thataffect transport and fate of contaminantshas improved options for effectiveremediation of chlorinated solvents inthe subsurface. Studies at the PicatinnyArsenal and at other sites have defined arange of natural microbial processes thattransform chlorinated solvents to lesstoxic chemicals.

• Waste Disposal and ContaminantMigration in the Arid Southwest -Amargosa Desert, Nevada. Themovement of moisture and radioactiveand organic contaminants in the thickzone between the land surface and thewater table is being studied. Such siteshave been selected for waste disposal inarid areas. Research is improvingknowledge of the potential and themechanisms for contaminant migrationin these environments.

• Crude Oil Contamination in theShallow Subsurface - Bemidji,Minnesota. Knowledge gained at thissite of the processes that controlmigration and fate of hydrocarbons inthe subsurface has facilitated adoption ofnatural bioremediation as a widelyaccepted remediation alternative forhydrocarbon contamination.

An array of vertical multi-point sampling devices installed to monitor small-scale subsurfacegeochemical heterogeneities in a contaminant plume at the Cape Cod, Massachusetts, researchsite. Knowledge and models developed at this site are employed at many sites with sparse data.

Vertical shaft (5 feet in diameter and 45 feetdeep) installed at the Amargosa DesertResearch Site provides access to measuremovement of moisture and contaminants in thedry zone above the water table.

• Subsurface Gasoline Spills may be themost frequently cited cause of ground-water contamination.- Conventional Gasoline -GallowayTownship, New Jersey. Models andfield methods have been developed toquantify natural attenuation ofcontaminants by biodegradation andvolatilization, and to enhance naturalattenuation using vapor extraction.- Oxygenated Gasoline - Laurel Bay,South Carolina. Use of Methyl tert-butyl ether (MTBE) as a fuel oxygenatechallenges the natural attenuationparadigm for remediation of gasolinespills. MTBE is resistant to degradationand moves readily in ground water.Research has documented how MTBEpersists in the subsurface and is focusingon the limits of natural attenuation andalternative remedial strategies.

• Sewage-Contaminated Ground Water-Massachusetts Military Reservation,Cape Cod, Massachusetts. A plume ofsewage-tainted ground waterdowngradient of a sewage disposal site isbeing studied. Measurements of verysmall-scale variations in contaminantconcentrations and results of field tracerexperiments are being used to improvemodels of how complex mixtures ofcontaminants move and attenuatenaturally in the subsurface.

Investigations of Watershed- andRegional-Scale Contamination

Watershed- and regional-scaleinvestigations address contaminationproblems typical of specific land uses orhuman activities that may pose a threat toenvironmental and human healththroughout significant parts of the Nation.These studies involve characterizingcontaminant sources and their mechanismsfor affecting aquatic ecosystems, such aswatersheds affected by abandoned mines.These studies involve widespreaddetection of compounds released to theenvironment through common use, such asuse of agricultural chemicals.Contaminants and degradation productsare measured at levels below existingwater-quality standards to assess whetherthey are actually entering the environmentand to define the mixtures in which theyoccur. The information provided by thesestudies is used for developing regulatorypolicies and standards, for registering theuse of new chemicals, for decisions on

what chemicals to manufacture, and fordevelopment of usage guidelines.

Investigations of watershed- and regional-scale contamination include:

• Contamination from AgriculturalChemicals - These investigationsaddress large-scale agricultural activitieswith similar crops and/or farmingpractices. They focus on characterizingprocesses that affect dispersal ofchemicals in the atmosphere, groundwater, and surface water; identifyingpersistent degradation products; anddeveloping methods to measure thesecompounds in water samples atenvironmentally relevant concentrations.Results are used by manufacturers,farmers, regulators, and the public. Twoinvestigations are under way.- The Midwest Corn Belt -This areaextends across parts of 12 states andaccounts for about 65 percent of the totalharvested cropland and 60 percent ofherbicide use in the Nation. The projectfocuses on characterizing the occurrence,transport, and fate of corn and soybeanherbicides and herbicide degradationproducts in streams, reservoirs, groundwater, rainwater, and air. Results of thestudy have influenced agriculturalchemical-use practices.- Cotton Agriculture Across theSouthern U.S. - Pesticide usage forcotton farming typically is three to fivetimes that for corn or soybeans. Theareas of intense cotton growing underinvestigation–the MississippiEmbayment, the High Plains of Texas,southern Arizona, and southernCalifornia–have varied hydrologicsettings and very different mechanismsfor contaminant migration in theenvironment.

• Human Influences on San FranciscoBay - Like all urban estuaries in theworld, San Francisco Bay receives toxicsubstances from a variety of natural andhuman sources. Studies here focus oncharacterizing the interrelated physical,chemical, and biological processes thataffect contamination within the Bay andthe delta ecosystems. Results of thesestudies are providing an understandingof the effects of contamination onspecies throughout the food chain and of

San Francisco Bay is affected by urban runoff,industrial and municipal discharges, andagricultural runoff from nearby fertile rivervalleys. (Landsat-7 image distributed by USGSEROS Data Center, Distributed Active ArchiveCenter.)

the effectiveness of resource-management strategies.

• Contamination from Hard RockMining - Thousands of historical hard-rock mines (such as gold, copper, andzinc mines) exist across the WesternUnited States. Mine dumps, tailing piles(the residue after ore processing), andunmined mineral deposits oftencontaminate the surrounding watershedand ecosystems when weathering ofexposed minerals results in acid drainageand metals-enriched waters. Research isfocusing on the processes that affectmigration of contamination within thewatershed and the resulting effects onthe ecosystem. Studies are under way intwo areas with differing climate andhydrologic settings. The results andmethods developed at these sites arebeing used and demonstrated through theUSGS Abandoned Mine Lands Initiative.

More than 800 samples from 303 wells in thetwelve “corn belt” states indicate that analyzingfor herbicide degradates is essential foraccurate estimation of the total mass andfrequency of detection of total herbicidecompounds.

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• Historical Hard-Rock Mining inRocky Mountain Terrain -Characterizing mining contamination inmountain streams is often confounded bythe facts that numerous sources can takeobscure pathways to the stream, andmuch streamflow can occur within thecoarse gravel streambed. Stream tracermethods, which were developed andtested in the upper Arkansas River,Colorado, have enabled identification ofspecific sources of streamcontamination.- Historical Hard-Rock Mining inSouthwest Alluvial Basins - In this aridarea, contaminants often are transportedgreat distances by ground water, andmay threaten regional water supplies. AtPinal Creek, Arizona, scientists arestudying the geochemical evolution of aplume of metals-laden ground water andits ultimate interaction with Pinal Creek.The goal is to develop and test improvedmodels of surface- and ground-waterinteraction, and ground-water transportthat are transferable to other areas withdifferent physical and chemicalcharacteristics.

- USGS Abandoned Mine Lands(AML) Initiative - The goal of thisInitiative is to develop a watershed- andscience-based strategy for cost-efficientcleanup of AML. The Initiative is underway in two pilot watersheds—the UpperAnimas River, Colorado, and theBoulder River, Montana. USGS isworking with federal land managers toclean up abandoned mines on or adjacentto public lands. The watershed approachhas enabled remedial actions to target themost serious contamination sources.

• A National Assessment of Mercury inAquatic Ecosystems - Recent dramaticincreases in fish-consumption advisoriesthat now are issued in 40 statesdemonstrate that mercury is a nationalconcern. Aquatic ecosystems across theNation are being studied to identify thecontrols on accumulation of mercury totoxic levels in the food chain.Ecosystems are being studied that areaffected by varied sources (mining,natural, and atmospheric sources) andhave varying potential to convertmercury to its most toxic form,methylmercury.

• Amphibian Research and MonitoringInitiative - Program scientists areproviding information on hydrology,ambient water quality, and occurrence ofcontaminants in support of this nationalmulti-agency Initiative. Monitoring isbeing conducted in seven regions.

Information will be used to quantifyamphibian population declines and toidentify potential causes.

• A National Reconnaissance ofEmerging Contaminants - Newcompounds continually enter theenvironment, either during intended use(such as pesticides and fumigants) or viaindustrial, human, or animal wastes(such as detergents, pharmaceuticals,antibiotics, and synthetic hormones).New low detection-level methods arebeing developed, and a national surveyof susceptible streams and wells is underway. This effort will provide the firstassessment of these compounds in theNation’s waters.

- Herbert T. Buxton

Clean sampling techniques enablemeasurement of mercury species at sub-nanogram per liter concentrations–essential forunderstanding environmental cycling andbioaccumulation in aquatic ecosystems.

Silverton, Colorado, at the mouth of the upper Animas River and its watershed in the background,where over 1,500 abandoned mine sites affect water and ecosystem quality.

For more information on theactivities of the Toxic SubstancesHydrology Program, visit our website at:

<http://toxics.usgs.gov/>

Or write to:

USGS Toxics Program MS 412 12201 Sunrise Valley Drive Reston, VA 20192