Poster Session 3, 1:15 PM - 2:00 PM: Campus Center Auditorium [A41]

Differences in Distributions & Lability of Contamination-Prone Trace Metals in the Kennebec, Sheepscot, & Damariscotta Rivers

Presenter: Bella Brown

Faculty Sponsor: Jesse Farmer

School: UMass Boston

Research Area: Geology and Earth Sciences

ABSTRACT

Rivers are key contributors to the oceans’ trace metal budget, supplying micronutrients to phytoplankton and driving coastal geochemistry. Trace metals have natural sources, but can act as conservative pollutants if leached from anthropogenic activities, bioaccumulating up trophic levels and affecting marine ecosystems. In the Gulf of Maine, riverine trace metal inputs are widely understudied. In this study, three rivers that empty into the Gulf of Maine– the Sheepscot, the Kennebec, and the Damariscotta– were analyzed to determine differences in chemical lability and potential anthropogenic input of contamination-prone trace metals. Dissolved, total particulate, and labile particulate concentrations of iron, lead, aluminum, and copper were measured using an ICP-MS with standard digestion methods. Higher concentrations of particulate and dissolved copper were found in the Sheepscot compared to assumed crustal abundance, suggesting different input methods or differences in cycling processes between rivers. Particulate lead was found have a labile fractionation of 49.61% to 74.74% compared to copper and aluminum’s 1-8%. Labile particulate lead concentrations covaried with labile particulate iron along the Sheepscot with a linear relationship (R2=0.993). Overall, the Damariscotta contained higher concentrations of labile lead, iron, and copper than the Sheepscot. These concentrations decreased at a more rapid rate than those of the Sheepscot as salinity increased. All three rivers showed decreasing concentrations of dissolved iron as salinity increased, with the Kennebec and Damariscotta showing evidence of estuarine removal of dissolved iron due to flocculation of iron colloids. This study addresses a key knowledge gap on trace metal composition and potential contamination in rivers of the Gulf of Maine.

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