Charli's Analysis

Interestingly, different heavy metals showed variable concentrations both throughout the pond system and into the pond’s core. Not only that, but different metals show different trends, suggesting that they were deposited into the sediment from different sources, and transit the system differently. Manganese and iron show a similar trend: each were found in their highest concentration at the stream’s source, and at similar concentrations through the remainder of the system. While both elements are natural components of soil, the fact that they have their highest concentration at the stream’s source suggests that they may be input to the stream externally—perhaps through runoff—and deposited at the source, and cannot travel further down the stream. Like manganese and iron, zinc concentrations are highest at the stream source, but the trends diverge in the rest of the system. Zinc has much lower concentrations through the rest of the stream, but concentrations rise again within the pond. This may suggest that the zinc in the stream source and in the pond have different sources. At the stream source, zinc may be a product of runoff that is deposited, like iron and manganese. Within the pond, zinc may also be coming from runoff from another source, like (road name), or it could be an old product of Paintshop Pond. Paintshop Pond, located just west of Lake Waban, is contaminated with various toxins and heavy metals (including zinc, copper, chromium, and lead) because of its proximity to Henry Wood’s Sons Paint Factory, which operated and dumped waste materials on-site from 1848 to the 1920s.^x Although the college has been remediating the pond since the 1970s, and Paramecium Pond dredges have taken place since then, it is likely that Paintshop Pond is the primary source of zinc, chromium, and copper in the pond. In fact, since chromium and copper are not present in the Silver Thread at detectable levels, it is possible that Paintshop Pond is the sole contributor of those elements to the pond. Lead is present at higher concentrations in the pond than the stream, but since it is detectable in stream sediment, it’s likely there is another contributing lead source to the stream. This source may be the pipes that feed the stream, or runoff.