ANALYSIS OF TOXIC METALS IN STREAM SEDIMENTS ALONG PIPER BROOK, PARK RIVER WATERSHED, CONNECTICUT

Piper Brook is a tributary of the South Branch of the Park River, and flows through a well-developed industrial district located in New Britain and Newington, CT. Piper Brook has been significantly transformed from its natural flow path in order to accommodate for increasing urbanization; as it is now partially channelized, locally runs through culverts, and was displaced by a railway and a major highway.

Piper Brook flows on Jurassic Portland arkose bedrock that is overlain by coarse-grained glacial deposits. Stream water quality data collected in early fall 2011 give conductivity values of ~300 µs/cm, and pH of ~8. In order to assess the potential for toxic trace metal contamination, 16 sediment samples (<64 micron fraction) were collected from 8 sites. Sampling sites are spaced from 570 to 2100 m. A weak acid digestion was used to prepare samples for ICP-OES analysis to determine the concentration of major trace metal elements.

Most metals analyzed have high concentrations. Copper values are very high, (187 to 610 ppm) and exceed Probable Effect Concentration (PEC) at all sites; while cadmium values range from <2.0 to 18.0 ppm and most sites exceed PEC. Arsenic has relatively low values of <0.3 to 2.9 ppm. Arsenic, copper and cadmium concentrations increase markedly downstream as Piper Brook passes through the industrial zone. Chromium values range from <15 to 127 ppm, with two sites exceeding PEC. Lead values range from <30 ppm to 244 ppm with most exceeding the Threshold Effect Concentration (TEC) while 4 sites exceed the PEC. Zinc values range form 90 to 572 ppm with most exceeding the TEC, while 3 sites exceed the PEC. Vanadium values range from <10 to 61 ppm and barium values range from <50 to 300 ppm. The high levels of metals in Piper Brook sediments are likely to negatively influence the stream ecosystem.