鄱阳湖不同高程沉积物中磷形态特征研究

选取了枯水期鄱阳湖10~13m高程共14个出露表层沉积物样品,通过研究其总磷(TP)及各形态磷含量与分布特征,试图揭示江湖关系变化导致的水位下降对鄱阳湖沉积物磷潜在释放风险的影响.结果表明,鄱阳湖表层沉积物总磷(TP)含量在214.5~736.0mg/kg之间, 平均含量为(428.6±154.3)mg/kg.空间分布呈“五河”入湖尾闾区(444.5mg/kg)≈湖心区(445.4mg/kg)>北部湖区(387.7mg/kg).各形态磷在空间上的差异相对较小,不同形态磷含量次序为活性磷(254.6±114.3mg/kg)>有机磷(105.0±49.2mg/kg)>非活性磷(69.1±26.3mg/kg).江湖关系变化引起鄱阳湖枯水期沉积物出露时间提前并且延长,进而导致不同高程沉积物总磷及其各形态磷含量差异明显,其含量变化趋势为12~13m> 11~12m>10~11m,即高程越高,沉积物总磷及其各形态磷含量越高.其中活性磷增幅最大,OP次之,非活性磷最小.而空间增幅表现出“五河”入湖尾闾区最为显著,湖心区次之,而北部湖区最小.

Distribution characteristics of phosphorus in sediments at different altitudes of Poyang Lake

The total phosphorous (TP) and various forms of phosphorus contents characteristics of Poyang Lake surface exposed sediments were studied, in order to reveal the influence of the water level descended resulted from the relationship between Yangtze River and the Poyang Lake changed on the potential phosphorus-release risk of Poyang Lake sediments. Results showed that: The TP contents of Poyang Lake surface sediments varied from 214.5 to 736.0mg/kg, and the average content of TP was (428.6±154.3)mg/kg, The TP contents in the estuary of “five rivers” and central area of Poyang Lake were closed, were 444.5mg/kg and 445.4mg/kg, the content in the north area was 387.7mg/kg which far less than the estuary of “five rivers” and central area of Poyang Lake. The spatial distribution of various forms of phosphorus of Poyang Lake surface sediments was relatively uniform, the average content of reactive phosphorous from Poyang Lake surface sediments was (254.6±114.3)mg/kg, non-reactive phosphorus was (69.1±26.3)mg/kg, and organic phosphorus was (105.0±49.2)mg/kg, their contents relationship was the reactive phosphorous > organic phosphorus > non-reactive phosphorus. The relationship between Yangtze River and the Poyang Lake changed, resulting in the low water level advanced and the outcropped time prolonged, then caused the TP and various forms of phosphorus contents increased with the elevation rise from 10~11m to 12~13m, and the growth rate of the reactive phosphorous was faster than organic phosphorus and non-reactive phosphorus. The growth in the estuary of “five rivers” was the most significant, the central area comes second, and the north area was the least.