As part of the National Water-Quality Assessment (NAWQA) Program, the U.S
Geological Survey (USGS) is conducting Source-Water Quality Assessments (SWQAs)
to characterize the occurrence and concentrations of anthropogenic organic compounds in
groundwater withdrawn from selected aquifers used for water supply. SWQAs are
intended to complement existing drinking water monitoring required by Federal, State,
and local programs, which focus primarily on post-treatment compliance monitoring. In
the first year, samples of source or raw water collected from about 15 production wells in
each of 11 study areas across the United States were analyzed for about 270
anthropogenic organic compounds that include pesticides, pesticide degradates,
polycyclic aromatic hydrocarbons, and volatile organic compounds (VOCs). Detection-
frequency and concentration criteria developed from the results of these analyses were
used to select a subset of the initial 163 wells for sampling during the second year of the
study. During the second year, samples of source water from 69 wells and of the
corresponding finished water were analyzed to characterize the extent to which
compounds detected in source water are detected in finished water.
Preliminary findings from the first year of sampling indicate that the five most frequently
detected compounds were the pesticides metolachlor, deethylatrazine, and atrazine with
detection frequencies of 52, 42, and 37 percent, respectively, and maximum
concentrations of 3.6, 0.3, and 0.4 micrograms per liter, respectively; the pesticide
degradate alachlor ethane sulfonic acid, with a detection frequency of 33 percent and a
maximum concentration of 0.6 micrograms per liter; and the VOC trichloromethane, with
a detection frequency of 47 percent and a maximum concentration of 13.5 micrograms
per liter. About 45 percent of the constituents analyzed for were detected at least once.
Results from the second year of sampling, which focuses on comparing concentrations of
anthropogenic organic compounds in source water to concentrations in finished water,
will enable NAWQA researchers to ascertain which compounds frequently found in
source water are entering the communities' distributions systems and the concentrations
at which they occur. Includes abstract only.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 650 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 1 |
| Published : | 11/01/2005 |
