武汉南湖水体及沉积物不同形态磷的季节变化

在武汉南湖5个采样点分别采集了湖水和柱状沉积物样品，对水体、沉积物及其间隙水中磷的季节变化以及沉积物中的不同形态磷进行了研究.结果表明: 水体总磷（TP）和正磷酸盐磷（PO₄^3--P）的平均含量分别为0.240和0.033 mg·L^-1.TP和PO₄^3--P均在11月含量最高，但TP含量的最低值出现在2月，PO₄^3--P含量的最低值出现在8月.沉积物中TP的平均含量为1.005 mg·g^-1, 4—11月呈上升趋势，11月至次年2月趋于稳定；其垂直分布上随沉积深度增加逐渐降低.其间隙水PO₄^3--P的平均含量为0.209 mg·L^-1，11月最高，2月最低，其垂直分布规律与沉积物TP一致.沉积物中的不同形态磷以无机磷为主，占TP的61.4%～77.1%.沉积物中活性磷（BA-P）的含量很高，但BA-P随沉积深度增加显著降低.相关性分析表明，沉积物主要通过BA-P和自生钙磷（ACa-P）的释放向水体供给磷.

Seasonal dynamics of phosphorus forms in water body and sediments of Nanhu Lake, Wuhan

Water samples and sediment cores were taken at 5 sites of Nanhu Lake, Wuhan to investigate the seasonal dynamics of phosphorus in water body, sediments and their interstitial water, as well as the phosphorus forms in sediments. The results showed that the average concentrations of total phosphorus (TP) and orthophosphate (PO₄^3--P) in water body were 0.240 and 0.033 mg·L^-1, respectively, with the highest concentrations of TP and PO₄^3--P in November and the lowest concentration of TP and of PO₄^3--P in February and August, respectively. The concentration of TP in sediments was averagely 1.005 mg·g^-1, being increased from April to November and becoming stable from November to February, and decreased with sedimentation depth. The concentration of PO₄^3--P in interstitial water was 0.209 mg·L^-1 on average, being the highest in November and the lowest in February, with the same vertical distribution pattern like TP in sediments. The dominant form of phosphorus in sediments was inorganic phosphorus (IP), occupying 61.4%-77.1% of total extracted phosphorus. The concentration of bio-available phosphorus (BA-P) in sediments was very high, but decreased significantly with sedimentation depth. According to the significant correlations between phosphorus forms in sediments and PO₄^3--P in interstitial water, the BA-P and auto-calcium bound phosphorus (ACa-P) in sediments should be the main P sources released from sediments to water body.