Using stable isotopes to trace sewage-derived material through Boston Harbor and Massachusetts Bay

Using stable isotopes, we assessed the effects of long-term sewage inputs w ithin Boston Harbor and extending into adjacent Massachusetts Bay. We used nitrogen and sulfur stable isotopes (delta(15)N and delta(34)S) to distingu ish between sources of these elements to sediments, particulate organic mat ter, algae, and animals. The isotope data revealed the widespread presence of sewage-derived particulate and dissolved materials. Incorporation of sew age-derived effluent particulates into sediments of the harbor and into Mas sachusetts Bay was apparent in the delta(15)N values of surface sediments a nd in sediment profiles. Changes towards more typical marine values over ti me indicated a lessening of sewage inputs. The incorporation of sewage part iculates into blue mussels as revealed by the combination of delta(15)N and delta(34)S values in their tissues was also evident and suggested the impo rtance of sewage-derived nutrients to the local food web. (C) 1999 Elsevier Science Ltd. All rights reserved.