吴晓丹,常凤鸣,吴斌,等. 南黄海表层沉积磷的赋存形态及其对水体富营养化态势的影响[J]. 海洋地质与第四纪地质,2023,43(5): 106-118. DOI: 10.16562/j.cnki.0256-1492.2023073101
引用本文: 吴晓丹,常凤鸣,吴斌,等. 南黄海表层沉积磷的赋存形态及其对水体富营养化态势的影响[J]. 海洋地质与第四纪地质,2023,43(5): 106-118. DOI: 10.16562/j.cnki.0256-1492.2023073101
WU Xiaodan,CHANG Fengming,WU Bin,et al. Forms of sedimentary phosphorus in the South Yellow Sea and the implication to regional eutrophication trend[J]. Marine Geology & Quaternary Geology,2023,43(5):106-118. DOI: 10.16562/j.cnki.0256-1492.2023073101
Citation: WU Xiaodan,CHANG Fengming,WU Bin,et al. Forms of sedimentary phosphorus in the South Yellow Sea and the implication to regional eutrophication trend[J]. Marine Geology & Quaternary Geology,2023,43(5):106-118. DOI: 10.16562/j.cnki.0256-1492.2023073101

南黄海表层沉积磷的赋存形态及其对水体富营养化态势的影响

Forms of sedimentary phosphorus in the South Yellow Sea and the implication to regional eutrophication trend

  • 摘要: 南黄海水体富营养化日益加剧,作为我国绿潮孕育和暴发的主要场所,其水体富营养化的形成演变机制仍未完全清楚。为解析该区沉积物中营养元素磷(P)的释放特征和对水体富营养化的潜在贡献,采用改进的连续浸取法(SEDEX)分析了表层沉积中磷的含量水平和赋存形态,探讨了其生物有效性和对水体富营养化态势的影响。研究表明:总磷(TP)平均值为514 mg/kg,处于轻度污染,以无机磷(IP)为主要赋存形态(76.39%),有机磷(OP)次之,IP又以Ca-P为主(30.17%)。各形态磷平均贡献依次为OP>Ca-P>De-P>Fe-P>Ex-P。Ca-P和De-P属于生物不可利用磷,在沉积物中稳定性较强,在较粗粒径沉积物中含量较高。Ex-P和Fe-P易吸附于细颗粒沉积物表面,pH、温度、水体动力和氧化还原条件等是影响其吸附-释放的主要因素,南黄海海水酸化将促进Ex-P和Fe-P向海水释放,加剧海水富营养化程度。OP变化趋势显示,近岸以陆源输入为主,远岸生物过程具有重要贡献。南黄海生物有效磷(BAP:Ex-P + Fe-P + OP)平均值为240.1 mg/kg,占TP的46.4%,表明研究区沉积磷生物可利用性较强,释放到水体的风险较高,对该区富营养化具有重要长期潜在贡献。

     

    Abstract: Eutrophication has been increasingly occurred in the South Yellow Sea (SYS), the main region of outbreak of green tide. However, the mechanism and evolution of eutrophication in this area remains not fully resolved. Concentrations and forms of the surface sediment phosphorus (P) in the SYS were determined by the modified sequential extraction method (SEDEX) to examine the bioavailability and potential contribution to the eutrophication. Results show that the mean value of total phosphorus (TP) in surface sediments was 514 mg/kg, being generally in a mildly contaminated condition. Inorganic phosphorus (IP) was the main form (76.39%), of which 30.17% was Ca-P. The average contribution of each P form was in the order of OP (organic P) > Ca-P (Ca bound P) > De-P (detritus P) > Fe-P (Fe bound P > Ex-P (exchangeable P). Ca-P and De-P are not bioavailable species, which are less easily released under normal hydrodynamic disturbance in sediments, and are generally enriched in coarse-grained sediments. Ex-P and Fe-P are easily adsorbed into fine-grained sediments, for which pH, temperature, hydrodynamics, and redox conditions are important environmental factors. Acidification of seawater in the SYS will elevate the release of Ex-P and Fe-P into seawater and worsen the degree of eutrophication. Distribution of OP indicated the contribution of biological processes in the open sea in addition to the terrestrial input in the nearshore. The mean value of bioavailable phosphorus including Ex-P, Fe-P and OP was 240.1 mg/kg, which accounted for 46.4% of TP, suggesting that sedimentary P in SYS is more bioavailable, showing a higher risk of P release into the water column, and an important long-term potential contributor to local eutrophication.

     

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