GEOCHEMICAL ANALYSIS OF THE NORTH RIVER DRAINAGE BASIN

The North River Drainage Basin is located north of Boston primarily running through the towns of Salem and Peabody, MA. The basin consists of three freshwater brooks Proctor Brook, Goldthwaite Brook and Strongwater Brook. It provides drainage from precipitation and runoff, and is a significant source of freshwater entering into the Salem Sound. The North River has a 240 year history of heavy industrial use by tanneries and other industries that used the river for means of disposal of unwanted waste products. Moreover, the region has undergone heavy urbanization as well as the construction of culverts and channels to suit the needs of the local industries and towns.

A geochemical analysis of the water was conducted using stream flow measuring equipment and a YSI chemical probe to determine the effects of runoff from streets, parking lots and other impermeable surfaces. Results from the geochemical analysis showed interesting relationships within the drainage basin, such as a stretch of Strongwater Brook showing increased salinity with higher temperatures. This may suggest that increased amounts of salt may be linked to seasonal changes in the river.

Additionally, heavy metals analysis of sediments within the drainage basin was conducted using x-ray fluorescence spectrometry. Results indicated elevated levels of chromium, lead, arsenic, copper, and zinc above the effective range low and median values for these elements. Concentrations above these values have been shown to adversely affect up to 10-50% of animals respectively. Examples include chromium concentrations exceeding 500ppm, 100ppm above the ERM value. These concentrations suggest that areas within the North River drainage basin could pose a possible risk for human health. The source of these contaminants is a likely result from past industrial use by tanneries known to use heavy metals such as chromium during the tanning process. An additional source of these heavy metals may be from pressurized wood lining the mouth of the North River. As the wood showed dangerous concentrations of several of the heavy metals found in sampled sediments.