The effects of anthropogenic nutrient inputs on stable carbon and nitrogen isotopes in suspended particulate organic matter in Jiaozhou Bay, China

• Published in: Continental shelf research Vol. 208; p. 104244
• Main Authors: Ke, Zhixin, Chen, Danting, Liu, Jiaxing, Tan, Yehui
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.12.2020
• Subjects: Anthropogenic influence; Coastal bay; Eutrophication; Sewage discharge; Urban river; Coastal bay; Anthropogenic influence; Sewage discharge; Urban river; Eutrophication
• ISSN: 0278-4343; 1873-6955
• DOI: 10.1016/j.csr.2020.104244

The values of δ13C and δ15N in POM and nutrient concentrations were investigated in the surface water of Jiaozhou Bay during spring, summer and autumn. Results showed that eutrophic conditions were generally the highest in the northeastern bay during the three seasons. It suggested the sewage from urban rivers were the major pollution source in the northeastern Jiaozhou Bay. The δ13C value of POM was significantly higher in the inner bay in spring, but lower in summer. Seasonal distribution of δ13C in POM seems depended on the balance between terrigenous organic matter input and in situ phytoplankton biomass. In contrast, δ15NPOM showed a consistent distribution pattern during the three seasons, where it was higher in the northwest and lower in the northeast. It suggests that a different source or intensity of anthropogenic nutrient loading may have an opposite effect on the δ15N value of POM. The significantly depleted 15N in POM indicated the strong influence of urban sewage in northeastern Jiaozhou Bay. This study suggested the δ13C and δ15N of POM can effectively indicate the influence of anthropogenic nutrients loading in coastal bays. However, the effects may vary depending on the source and strength of nutrients loading. •Urban wastewater has become a major source of pollution in Jiaozhou Bay.•δ13CPOM depend on the balance between terrigenous OM and phytoplankton.•Anthropogenic nutrient loading may have opposite effect on δ15NPOM.•Lower δ15NPOM indicate strong influence of urban wastewater discharge.