Terrestrial input and nutrient change reflected by sediment records of the Changjiang River Estuary in recent 80 years
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Terrestrial input and nutrient change reflected by sediment records of the Changjiang River Estuary in recent 80 years LI Junlong1, 2, 3, ZHENG Binghui2*, HU Xupeng4, WANG Yiming4, DING Ye3, LIU Fang3 1 2
College of Water Sciences, Beijing Normal University, Beijing 100875, China State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
3
State Environmental Protection Key Laboratory of Quality Control in Environmental Monitoring, China National Environmental Monitoring Center, Beijing 100012, China
4
Zhoushan Marine Ecological Environmental Monitoring Station, Zhoushan 316000, China
Received 12 November 2013; accepted 25 April 2014 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2015 Abstract A variety of environmental problems have been observed in the Changjiang River Estuary and adjacent coastal area, including eutrophication, harmful algal blooms (HABs), and hypoxia in recent decades. Application of sedimentary biogenic element indicators on the study of paleoenvironment can reconstruct environmental evolution history of waters. Two 210Pb-dated cores were collected from the Changjiang River Estuary (S3) and adjacent coastal area (Z13), and total organic carbon (TOC), total nitrogen (TN), biogenic silicon (BSi), total phosphorus (TP) and phosphorus (P) species were analyzed. Three stages of environmental changes are deduced by the nutrient sedimentary records. First, nutrient concentration increased rapidly since the 1950s, which attributed to agriculture development and overused chemical fertilizers. Second, nutrient concentration kept high and primary production began to promote during the 1960s to 1980s, while diatom abundance and proportion began to decline since the 1970s, accompanied by reduced SiO23− concentration and flux from the river. Third, due to several dams and bridges constructed, river runoff and coastal hydrodynamic conditions reduced to a certain extent since the 1990s, which aggravated the unbalance in nutrient structure. Multi-nutrient proxies in sediment can reflect the natural environm-ental changes as well as influence of human activities. Key words: biogenic elements, phosphorus species, sediment cores, Changjiang River Estuary Citation: Li Junlong, Zheng Binghui, Hu Xupeng, Wang Yiming, Ding Ye, Liu Fang. 2015. Terrestrial input and nutrient change reflected by sediment records of the Changjiang River Estuary in recent 80 years. Acta Oceanologica Sinica, 34(2): 27–35, doi: 10.1007/s13131-015-0617-8
1 Introduction Environmental information can be preserved in the sedimentary records when the particulate matter settled from water to the seabed. The past environmental conditions can be reconstructed with sedimentary chemical indicators to reflect the influence of climate change and human activities on water ecological system. The accumulation of TOC, N, BSi and P in sediments provide information about the settlement and preservation of these substances, and they can indicate
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