长江口及其邻近海域沉积物磷的赋存形态和空间分布

Fractions and spatial distribution of phosphorus in sediments of the Yangtze Estuary and adjacent marine zones

采用SMT磷分级法研究长江口及其邻近海域沉积物中磷的赋存形态及分布特征,并探讨了其影响因子.研究结果表明,沉积物中总磷(TP)含量为476.91~980.04μg·g^(-1),有机磷(OP)含量为15.84~139.21μg·g^(-1);而无机磷(IP)为主要赋存形态,其含量为421.67~844.86μg·g^(-1),约占TP 72.9%~96.7%.IP中以钙结合态磷(HCl-P)为主,其含量为186.88~431.69μg·g^(-1),占IP的42.3%~57.79%;而铁/锰结合态磷(Na OH-P)的含量最少,其含量为4.17~52.76μg·g^(-1),仅占IP的2.0%~3.3%.空间分布上,不同形态磷含量具有明显的时空变化特征.夏季TP和IP的含量由咸水端到淡水端呈现出先降低后升高,冬季则先升高后降低的趋势.OP的含量在夏季时无明显分布规律,而在冬季时表现出由咸水端到淡水端降低的趋势.Na OH-P含量在冬夏季均表现为淡水端处较高;HCl-P含量在夏季无明显的变化规律,而冬季时近淡水端处较高.沉积物粒径大小影响磷的赋存形态,表现为夏季粘粒对OP影响较大;冬季粘粒和粉粒与IP存在着负相关性,与OP存在着显著的正相关性.此外,沉积物总有机碳、盐度和碱性磷酸酶活性也是影响磷赋存形态的主要因子.

The fractions and distribution of phosphorus in sediments of the Yangtze Estuary and its adjacent marine and associated environmental variables were studied based on SMT phosphorus classification method. The results indicate that the total and organic phosphorus in sediments ranged from 476.91 to 980.04 μg·g-1 and 15.84～ 139.21 μg·g-1 , respectively. Inorganic phosphorus was the predominate form of phosphorus, with content of 186.88～431.69 μg·g-1 , accounting for 72.9% -96.7% of total phosphorus. The P linked to calcium （HC1-P） was in the range of 186.88-431.69 μg·g-1 , accounting for 42.27% ～57.79% of inorganic phosphorus. However, relative low concentration of P linked to Fe/Mn （NaOH-P） was in the range of 4.17 ～ 52.76μg· g- 1, accounting for 2.00% ～ 3.27% of inorganic phosphorus. The contents of different forms of phosphorus differed in space and time. Total phosphorus concentration in summer shows decreasing first and then increasing, while opposite variation trend was observed in winter from saltwater to freshwater zones. The organic phosphorus had no spatial variation in summer, while a decreasing trend from saltwater to freshwater zones was observed in winter. The content of NaOH-P was higher in freshwater than in saltwater zones. However, there was no obvious spatial variations of HC1-P in summer, and slight high contents near the freshwater zones were observed. The results of correlation analysis show that the particle size was the key factor affecting the forms of phosphorus in the sediments. Specifically, clay was significantly related to organic phosphorus in summer, while clay and silt show significant negative correlation with inorganic phosphorus and positive relation to organic phosphorus in winter. In addition, TOC, salinity and alkaline phosphatase were main factors affecting forms of phosphorus in sediments.