Bioaccumulation of Contaminants of Emerging Concern
Since the population explosion on Cape Cod in the 1980s, the health of Nantucket Sound and its numerous coastal ponds and embayments has become a concern. With increased residential and commercial development of Cape Cod come increased deleterious impacts on proximate waters. On Cape Cod, the major cause of coastal eutrophication is excess nitrogen from septic systems which discharge to groundwater. Septic systems serve more than 85 percent of commercial and residential developments, and the Cape Cod subsurface primarily consists of glacial till, a porous medium which allows for high rates of groundwater flow. The nitrogen-enriched water that stems from the Capeâ€™s high density of septic tanks eventually enters coastal waters via subsurface groundwater discharge. In addition to eutrophication, there are other potentially harmful contaminants associated with wastewater discharges broadly classified as contaminants of emerging concern (CECs).
CECs encompass a variety of natural and manmade chemicals including pharmaceuticals, hormones, personal care products, household cleansers, industrial chemicals and detergents. They can be introduced into the environment through a number of pathways but are predominantly associated with wastewater.
Â Previous research by the Silent Spring Institute has documented the presence of CECs in the Cape Cod ecosystem, both in freshwater ponds and commercial and private wells. Given the hydrologic connection between Cape Cod groundwater and proximate coastal waters, it was not surprising that research conducted by CCS beginning in 2010 has also documented the presence of CECs in our coastal waters.
The presence of any contaminants in the environment is particularly problematic if they bioaccumulate or elicit a toxicological response. Therefore, with funds provided by the Massachusetts Environmental Trust, CCS, in collaboration with several other organizations, implemented a study to measure time-integrated water concentrations of CECs and compare those data to concentrations in oyster tissue to investigate bioavailability.
In the fall of 2014, passive samplers and oyster seed were deployed at six sites on Cape Cod and the Islands. After approximately 40 days, the samplers and gear were retrieved and sent to Eurofins Laboratory for analysis for 73 CECs including hormones, pharmaceuticals, and personal care products. Several CECs were detected in both the passive samplers and the oyster tissue albeit at extremely low levels (parts per trillion). Initial results indicate that the passive samplers did accumulate more CECs than the oysters suggesting that that oysters do accumulate some, but not all, of the CECs that are found in the environment. Further work needs to be done to address potential environmental impacts and incorporation into the food chain.