Changes to nitrate isotopic composition of wastewater treatment effluent and rivers after upgrades to tertiary treatment in the Narragansett Bay watershed, RI

MARINE POLLUTION BULLETIN

卷:104

Article

Schmidt, Courtney E.¹  Robinson, Rebecca S.¹  Fields, Lindsey^1,2  Nixon, Scott W.¹ 

[1] Univ Rhode Isl, Grad Sch Oceanog, South Ferry Rd, Narragansett, RI 02882 USA

[2] Univ Georgia, Dept Marine Sci, 325 Sanford Dr, Athens, GA 30602 USA

关键词: Wastewater treatment;    Tertiary treatment;    Denitrification;    Nitrate;    Nitrogen and oxygen isotopes;    Narragansett Bay;   

DOI  :  10.1016/j.marpolbul.2016.02.010

来源: Elsevier

【 摘 要 】

Due to nitrogen load reduction policies, wastewater treatment facilities (WWTFs) have upgraded to tertiary treatment - where denitrification reduces and removes nitrogen. Changes to the stable isotopic composition of nitrate inputs after upgrades or how it transfers to the estuary have not been assessed in Rhode Island. We investigate whether these upgrades impact the isotopic signature of nitrate inputs to Narragansett Bay. Samples from rivers and WWTFs discharging to Narragansett Bay characterize the anthropogenic source nitrate (NO3-) isotopic composition (delta N-15-NO3- and delta O-18-NO3-) and temporal variability. At one WWTF, tertiary treatment increased effluent nitrate delta N-15-NO3- and delta O-18-NO3- values by similar to 16 parts per thousand. Riverine values increased by similar to 4 parts per thousand, likely due to the combination of decreases in N and upgrades. Combined river and WWTF flux-weighted isotopic compositions showed enriched values and an amplitude reduction in monthly variability. When seasonal isotopic means are significantly different from other sources, delta N-15-NO3- may be a useful tracer of inputs. (C) 2016 Elsevier Ltd. All rights reserved.

【 授权许可】

Free