Inputs of Fossil Carbon from Wastewater Treatment Plants to US Rivers and Oceans.
Publication Type:
Journal ArticleSource:
Environmental Science & Technology, Volume 43, Issue 15, Number 15, p.5647-5651 (2009)ISBN:
0013-936XKeywords:
c-14 data, DISSOLVED ORGANIC-MATTER, doc, ecosystem, estuarine, fate, food web, isotopes, marine, sedimentsAbstract:
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 ((14)C) 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 delta(13)C of -26.0 +/- 1 parts 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.