Abstract
In this study, we examined the nitrogen dynamics of a highly urbanized coastal area, focusing on the impacts of sewage-derived nitrogen. High levels of dissolved inorganic nitrogen were detected in seawater near treated sewage effluent (TSE) discharge points before decreasing in the offshore direction, suggesting that the impact zone of sewage effluent is about 1–2 km from the discharge point. The stable isotope ratios of nitrate and particulate organic nitrogen suggest nitrogen uptake by phytoplankton as well as dilution by offshore seawater, which contributed to a decrease in sewage-derived nitrogen levels. However, the extent of the impact zone was controlled by tidal variations and differences in temperature between the TSE and seawater. Our results also identify nitrogen transport processes, through exchange between seawater and sediment pore water, as an additional important source of nitrogen in the study area.
Highlights
Human activities significantly influence the global nitrogen cycle and natural water environments such as rivers and coastal seas (Vitousek et al 1997; Gruber and Galloway 2008)
We examined the nitrogen dynamics of a highly urbanized coastal area of western Japan that is influenced by sewage-derived nitrogen loads
The dissolved total nitrogen (DTN) concentration in the treated sewage effluent (TSE) was lower for SU (8 mg L−1) than for KH (14 mg L−1) (Table 1); the designed treatment population for SU is electrical conductivity (EC)
Summary
Human activities significantly influence the global nitrogen cycle and natural water environments such as rivers and coastal seas (Vitousek et al 1997; Gruber and Galloway 2008). Offshore seawater samples were collected approximately 7 km from the STP on the SA line in September and October 2014.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
