IMPACT OF ROAD POLLUTION AND RUNOFF ON THE HEAVY METAL CONCENTRATIONS OF SEDIMENTS WITHIN THE FOREST RIVER ESTUARY, SALEM, MA

Much research has been done assessing the potential for the contamination of sediments with heavy metals from runoff. The Forest River estuary in Salem, MA has already been shown to contain sediments contaminated with heavy metals which were argued to most likely originate from previous industrial activity. However, concentrations of heavy metals tended to be highest around outfall pipes that carry runoff from roads into the estuary. Heavy metals on roads can be derived from various sources such as road paint, vehicle emissions, wearing of brake pads, and other sources which eventually end up in the estuary through runoff. The purpose of this study is to determine whether or not runoff is a major source of contaminants to the sediments of the estuary. Road dust from several nearby drains and outfall pipes were sampled. The samples were then dried, homogenized and analyzed by pED-XRF. The samples were analyzed for bulk concentrations of cadmium, chromium, copper, lead, nickel, silver, and zinc. Lead, zinc, and copper all were shown to have 1.2-1.7 times greater mean concentrations at the outfall pipes than they were shown to have at any of the road drains. Silver, nickel, cadmium and chromium all had mean concentrations of minimal difference, less than 4ppm, from road drain to outfall pipe. Mean concentrations were used due to the concentrations of each metal varying too greatly from road drain to road drain and outfall pipe to outfall pipe. This is likely due to the distribution of metals being linked to traffic volume and congestion. Chromium, cadmium, lead, and copper all have concentration ranges of 64.7-159.9ppm, 4.8-6.3ppm, 37.2 to 97ppm and 14-68.8ppm respectively, which are in most cases lower than the previously recorded mean concentrations of these metals at 250.42ppm, 6.89ppm, 211.15ppm, and 45.93ppm for the estuarine sediments. This indicates that runoff is not a major source of these metals in the estuary; however, silver, zinc, and nickel all have concentrations at the road drains ranging from 20-26.7ppm 76.5-243.4ppm, 23.5-42.5ppm respectively which are, in most cases, equal to or higher than the previously recorded mean concentrations of these metals at 4.47ppm, 110.18ppm, 31.08ppm in the estuarine sediments. Therefore, runoff may be a major contributor of these metals to the sediment of the Forest River estuary.