Carbon and nitrogen stable isotopic signatures of suspended particulate organic matter and seawater biological oxygen demand (BOD) were measured along a coastal transect during summer 2015 to investigate pollution impacts of a high-discharge submarine sewage outfall close to Salvador, Brazil. Impacts of untreated sewage discharge were evident at the outfall site by depleted δ13Corg and δ15N signatures and 4-fold increased BOD rates. Pollution effects of a sewage plume were detectable for more than 6 km downstream from the outfall site, as seasonal wind- and tide-driven shelf hydrodynamics facilitated its advective transport into near-shore waters. There, sewage pollution was detectable at recreational beaches by depleted stable isotope signatures and elevated BOD rates at high tides, suggesting high bacterial activity and increased infection risk by human pathogens. These findings indicate the urgent necessity for appropriate wastewater treatment in Salvador to achieve acceptable standards for released effluents and coastal zone water quality.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We are grateful to the Institute of Geosciences at the Federal University of Bahia for logistical support. D. Dasbach, C. Staschock and D. Peterke (ZMT) are acknowledged for analytical support. RKPK is fellow (PQ-1D) of the National Council for the Scientific and Technological Development (CNPq). This work was funded by the European Commission 7th Framework Program Marie Curie Actions—People Grant PIRSES-GA-2011-295191 through the project SymbioCoRe (Synergies Through Merging Biological and Biogeochemical Expertise in Coral Research).
ASJC Scopus subject areas
- Aquatic Science