The overall objective of the project is to identify sources of arsenic to the Wallkill River Watershed. Individual objectives include:
Determining whether arsenic (and other trace element) concentrations in surface water vary diurnally, in order to select an optimum time for sampling;
Verifying reaches of the Wallkill River where arsenic concentrations are elevated relative to New Jersey surface-water-quality standards and determining concentrations of associated trace elements;
Determining potential anthropogenic sources by evaluation of historic and existing land uses;
# Determining the constituents that have increased (likely from increased development) in stream water over time by analysis of historic water-quality data; Determining the combinations of other elements associated with arsenic that can be used as chemical fingerprints of the three major groups of arsenic sources (geologic, disturbed geologic, and anthropogenic); fingerprinting would start with sediments, and the concept would be extended, if possible, to surface and ground water;
Determining whether water that has flooded the abandoned Franklin and Sterling Hill mines contains high levels of arsenic leached from the surrounding bedrock, as well as other elements useful in establishing a chemical fingerprint for water in contact with the highly mineralized marble bedrock formation;
Identifying whether domestic wells in different lithologies are tapping water with elevated concentrations of arsenic and whether ground water is a major source of arsenic in base flow.
Statement of Problem
Arsenic concentrations in water from the Wallkill River and Papakating Creek have been found to exceed the SWQS. Background data needs to be collected to support establishment of TMDLs by NJDEP at five sites on the Wallkill and one on the Papakating. Ground water in wells in the watershed also may tap water with arsenic levels that could exceed the proposed NJDWS. Potential sources of arsenic to water from the Papakating Creek and the Wallkill River include runoff containing residues of land applications of arsenical compounds, arsenic released from direct discharges to the streams, discharge of ground water containing trace elements contributed by geologic materials, and desorption of arsenic from stream sediments derived from soils and geologic materials.
Strategy and Approach
To characterize potential arsenic sources, GIS coverages of the region’s geology, both bedrock and surficial (including metadata) will be created from the USGS GIS library, or, if needed, acquired. Land-use data, including GIS coverage of agricultural areas and mine locations (including metadata) will be compiled, and historic aerial photography of the watershed will be evaluated.
To determine diurnal variations in metal concentrations in stream water during active photosynthesis, two ISCO samplers will be deployed during August to obtain trace-element data for stream water from the Wallkill River.
On the basis of results of bi-hourly samples, optimum sampling time for obtaining the highest concentrations of arsenic in stream water will be determined and samples will be collected at that time for analysis of arsenic and other trace elements, major ions, nutrients, and chemical characteristics such as pH and Eh. Surface-water samples under base-flow conditions will be collected at 6 locations along the Wallkill River and two locations on Papakating Creek.
To determine trace-element content of bottom sediment samples and upland sources of sediments to the river and creek, samples of stream-bottom sediments will be collected at the same locations as surface-water samples during the first (low-flow) sampling event. Additional stream-bottom sediment samples from the Wallkill River at Lake Mohawk and from Franklin Pond; from tributaries to the Wallkill River at two locations above Ogdensburg, at the Wildcat Brook, above and below Hamburg, at Beaver Run, and above Wantage; from two additional locations on the Papakating Creek and a tributary, above and below Sussex, and farther up the Papakating, near Wykertown, will be collected upstream of road crossings.
To amplify existing data for the quality of the area’s ground water, particularly that from domestic wells, previously unsampled domestic wells within 0.5 mile of the Papakating Creek and the Wallkill River channels will be sampled—3-4 domestic wells completed in the Quaternary deposits (stratified drift), 3-4 in the area’s clastic rock formations (primarily the Martinsburg Shale), 3-4 completed in the carbonate formations (Allentown Dolomite, Leithsville Formation, Jacksonburg Limestone), 5-6 in the Franklin Marble (if possible), 4-5 in the gneisses with preference given to those closest to the Franklin and Sterling Hill mines.
To determine relations between arsenic and other chemical constituents in stream water and hydrologic conditions, existing water-quality data will be analyzed for correlations between constituents, for trends with stream flow, for seasonal trends, and, where possible, analyzed for trends in constituent concentrations over time. To develop chemical fingerprints for possible arsenic sources, statistical and graphical techniques used in previous investigations (Barringer et al., 1998; Barringer et al., 2001) will be tailored to the proposed study