Cycling of phosphorus in the Jiaozhou Bay
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Cycling of phosphorus in the Jiaozhou Bay QI Xiaohong1 , LIU Sumei1∗ , ZHANG Jing1,2 , REN Jingling1 , ZHANG Guiling1 1
Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
2
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
Received 12 January 2010; accepted 2 July 2010 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2010
Abstract Dissolved inorganic phosphorus (DIP ), dissolved organic phosphorus (DOP ), particulate inorganic phosphorus (P IP ) and particulate organic phosphorus (P OP ) in the Jiaozhou Bay (JZB) and its adjacent major rivers were analyzed during 2001–2003. DIP was the major form of dissolved phosphorus in JZB, representing 62%–83% of the total dissolved phosphorus (T DP ), and the P IP concentration generally exceeded the P OP concentration. The concentrations of phosphorus were higher in the north than in the south of the bay, which were related to the fluvial input and water exchange rate. The dissolved phosphorus concentrations were higher in the autumn and spring than in the summer, while the seasonal variation of particulate phosphorus showed opposite pattern. The distribution of phosphorus is mainly affected by the growth of phytoplankton, desorption/adsorption of DIP from and to particulates, and anthropogenic activities. A preliminary phosphorus budget was established. In JZB, riverine input and water exchange flow between JZB and the Huanghai (Yellow) Sea are the major sources of phosphorus, followed by industrial and domestic waste transport, and then atmospheric deposition. Phosphorus burial efficiency is estimated to be 91%. About 52.2×106 mol/a of phosphorus were assimilated by phytoplankton, of which about 68% was recycled in the water column and sediment. Key words: phosphorus, cycling, suspended particulate matter, sediment, rive, the Jiaozhou Bay
1 Introduction Increased nutrient concentrations and/or changing nutrient ratios have been clearly shown to reduce food web diversity, alter phytoplankton composition and even increase the intensity and frequency of harmful algal blooms (Humborg et al., 1997; Turner, 2002). Phosphorus is an essential element in regulating marine productivity in marine ecosystems such as the Mediterranean Sea (Krom et al., 1991), the Huanghe Estuary and Laizhou Bay (Turner et al., 1990; Zhang et al., 2004a). Its role as a limiting nutrient for primary productivity inextricably links it to the global carbon cycle and thus the climate system over a geologic time scale (Paytan and McLaughlin, 2007). However, there remain many unanswered questions or ambiguous answers to phosphorus cycling in marine ecosystems (Benitez-Nelson, 2000). Pinpointing the sources and sinks of this globally important element remain elusive, and changes of either one could greatly alter the residence time of phosphorus in the ocean and, thus, estimates of its contribution to carbon export through ocean productivity (Paytan
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