ANTHROPOGENIC IMPACTS TO RIVER SEDIMENT IN MASSACHUSETTS RIVERS

Sediment quality in suburban stretches of four Southeastern Massachusetts riverways (Charles River (Medway), Neponset River (Norwood), Cushings Brook (Hanover) and Furnace Brook (Quincy)) was tested to determine the levels of sediment pollutants associated with non-point sources. On each river, six sediment samples were collected from a contiguous reach and analyzed for total organic carbon (TOC), grain size, extractable petroleum hydrocarbons (EPH), polycyclic aromatic hydrocarbons (PAHs), arsenic, lead and chromium. Water quality parameters (dissolved oxygen, pH, temperature, turbidity, and conductivity) also were recorded at each sample station. All river sediments generally consisted of sand and silt, with minor amounts of clay. EPH fractions, PAHs and metals were detected in every sample collected within each river stretch. Among all samples from each river stretch, the ranges of concentrations of contaminants were typically within one to two orders of magnitude.

Discrimination patterns of the constituents detected were compared to available data describing similar compounds in bituminous pavement and pavement coatings. The patterns of these constituents were generally reflective of those associated with anthropogenic impacts resulting from storm water/roadway runoff, with heavier-weight PAHs and EPH fractions predominant. In most samples, detected concentrations of constituents exceeded these screening levels. A comparison was also made with sediment testing results from recent studies by others including USGS (Mystic River Basin and Lower Neponset River). Sediment quality results were also compared to consensus-based ecological sediment screening levels as a means of assessing potential toxicity to benthic invertebrates. The study further documents the ubiquitous presence of these contaminants in sediments of suburban rivers and underscores the importance of considering non-point sources of contamination in suburban/urban waterways when planning assessment activities and evaluating impacts to, and as a result of, sediment quality.