Inputs of fossil carbon from wastewater treatment plants to U.S. rivers and oceans.
Every day more than 500 million cubic meters of treated wastewater are discharged into rivers, estuaries, and oceans, an amount slightly less than the average flow of the Danube River. Typically, wastewaters have high organic carbon (OC) concentrations and represent a large fraction of total river flow and a higher fraction of river OC in densely populated watersheds. Here, we report the first direct measurements of radiocarbon (14C) in municipal wastewater treatment plant (WWTP) effluent. The radiocarbon ages of particulate and dissolved organic carbon (POC and DOC) in effluent are old and relatively uniform across a range of WWTPs in New York and Connecticut Wastewater DOC has a mean radiocarbon age of 1630 +/- 500 years B.P. and a mean delta13C of -26.0 +/- 1 per thousand. Mass balance calculations indicate that 25% of wastewater DOC is fossil carbon, which is likely derived from petroleum-based household products such as detergents and pharmaceuticals. These findings warrant reevaluation of the "apparent age" of riverine DOC, the total flux of petroleum carbon to U.S. oceans, and OC source assignments in waters impacted by sewage.
Griffith
David R
DR
School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA. griffdr@mit.edu
Barnes
Rebecca T
RT
Raymond
Peter A
PA
D002244:Carbon / Q000032:analysis* / Q000633:toxicity; D002247:Carbon Isotopes; D003902:Detergents / Q000494:pharmacology; D004784:Environmental Monitoring / Q000379:methods; D005580:Fossils; D019015:Geologic Sediments; D009792:Oceans and Seas; D045483:Rivers; D012722:Sewage; D014481:United States; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods
D002247:Carbon Isotopes; D003902:Detergents; D012722:Sewage; D014874:Water Pollutants, Chemical; D002244:Carbon