title: Long-term changes in nutrients, chlorophyll a and their relationships in a semi-enclosed eutrophic ecosystem, Bohai Bay, China.
abstract: As the representative semi-enclosed bay of China, Bohai Bay has experienced severe eutrophication in recent decades. Monitoring data from 1995 to 2013 were analysed by generalized additive models (GAMs) to explore the temporal variations in nutrients concentrations, nutrient ratios, chlorophyll a (Chl a) concentrations and the responses of Chl a to the changes in nutrients in the spring and summer. The results showed that dissolved inorganic nitrogen (DIN) decreased from 1995 to 2000 but increased after 2000 in both the spring and summer, and soluble reactive phosphorus (SRP) decreased while the molar nitrogen/phosphorus (N/P) ratios (DIN to SRP) increased over the last two decades. Generally, P-limited phytoplankton growth was observed in the spring and summer and DIN was identified as the main pollutant constituent in Bohai Bay. Furthermore, negative correlations were found between DIN and Chl a in summer in Bohai Bay.
authors.affiliation: Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Yinhuan
authors.initials: Y
authors.lastname: Qiao
authors.affiliation: Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China. Electronic address: fengjf@nankai.edu.cn.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Feng
authors.affiliation: Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Shangfa
authors.initials: S
authors.lastname: Cui
authors.affiliation: Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhu
mesh_terms: D061006:Bays; D002681:China; D002734:Chlorophyll / Q000032:analysis*; D000077194:Chlorophyll A; D017753:Ecosystem; D004784:Environmental Monitoring; D005068:Eutrophication; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010839:Phytoplankton; D012621:Seasons; D012623:Seawater; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: Bohai Bay; Chlorophyll a; Generalized additive models; Nitrogen; Phosphorus