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LABORATORY ANALYSIS FOR ARSENIC IN DRINKING WATER SAMPLES
Citation:
Francis*, B. LABORATORY ANALYSIS FOR ARSENIC IN DRINKING WATER SAMPLES. Presented at EPA Science Forum, Washington, DC, May 31 - June 03, 2004.
Impact/Purpose:
To inform the public.
Description:
The U.S. Environmental Protection Agency (USEPA) has established maximum contaminant levels ( MCLs ), for many inorganic contaminants found in drinking water, to protect the health of consumers. Some of these chemicals occur naturally in source waters while some are the result of human contamination. Arsenic in water has been a recent regulatory focus of the USEPA. Relatively new health effects research prompted the USEPA to reduce the arsenic standard from 0.050 mg/L to 0.010 mg/L. Public water systems will have until February 2006 to be in compliance with the new rule.
Changing from one water treatment process to another can alter the chemistry of the output water. These changes may cause leaching of built-up deposits, which may contain trace contaminants such as arsenic, within the drinking water distribution pipes thereby creating additional problems. Studies are currently being conducted to determine whether arsenic will leach from distribution system solids.
Also, ongoing studies, lasting 3 months at a time, are conducted at the EPA laboratories using a small-scale water treatment plant to determine the effects of oxidation-reduction potential on the corrosion of copper, lead, iron, and brass piping.
These studies require analytical support to completely characterize the water chemistry during these testing phases. One analytical technique determines the concentration of 21 to 28 different elements, simultaneously in samples of water. This analysis is conducted on an inductively coupled argon plasma atomic emission spectrometer (ICAP-AES). The analytical technique determines these elements in the 0.0001 to 100 mg/L range. This information is employed to determine relationships and interdependency of the major background components and the elements of interest; arsenic, copper, lead and iron.
These measurements are charted over the three-month study period and reveal changes in the amounts of chemicals found in the water during that time. The results of this testing reveal the effects of the various changes and provide guidance for municipal water treatment plants throughout the United States.