蠡湖表层沉积物中磷的形态与赋存特征及其生物有效性

采用连续分级提取法研究了蠡湖表层沉积物中有机磷和无机磷的形态及其赋存特征,同时结合间隙水体中DTP(溶解性总磷)的空间分布特征,讨论了各形态磷的生物有效性及其释放风险. 结果表明,蠡湖沉积物中的磷以IP(无机磷)为主,w(IP)占w(TP)的58.09%. IP中以生物可利用性差的Ca-P_i(Ca结合态无机磷)占优势,w(Ca-P_i)为(207.75±48.56)mg/kg,占w(IP)的48.97%；沉积物OP(有机磷)中以活性最差的NA-P_o(非活性有机磷)占绝对优势,w(NA-P_o)为(195.33±50.73)mg/kg,占w(OP)的67.09%. 间隙水中的磷以DIP(溶解性无机磷)为主,ρ(DIP)占ρ(DTP)的11.86%~86.13%,平均值为59.65%. WA-P_i(弱吸附态无机磷)、PA-P_i(潜在活性无机磷)、Fe/Al-P_i(Fe/Al结合态无机磷)、WA-P_o(弱吸附态有机磷)、PA-P_o(潜在活性有机磷)的质量分数均与间隙水中ρ(DTP)呈极显著正相关(P<0.01),w(Ca-P_i)与间隙水中ρ(DTP)呈正相关(P<0.05),w(NA-P_o)与间隙水中ρ(DTP)无显著的相关性. 因此,即使在外源磷得到有效控制的情况下,沉积物中的IP及高活性有机磷的释放仍有可能导致湖泊富营养化状态维持不变. 

Forms, Occurrence Characteristics and Biological of Phosphorus in Surface Sediments of Lihu Lake

Forms and occurrence characteristics of organic phosphorus and inorganic phosphorus in the surface sediments of Lihu Lake were studied by sequential extraction method, and the bio-availability and release risk of phosphorus in various forms were also discussed, in combination with the spatial distribution characteristics of the total dissolved phosphorus in the interstitial water. IP was the main phosphorus form in Lihu Lake sediments, and w(IP) accounted for 58.09% of w(TP). The value of w(Ca-P_i) was (207.75±48.56) mg/kg, accounting for 48.97% of w(IP), and Ca-P_i was the main form of IP. NA-P_o dominated OP in the sediments, and w(NA-P_o) was (195.33±50.73) mg/kg, accounting for 67.09% of w(OP). Phosphorus in pore water was dominated by DIP; the proportion of ρ(DIP) in ρ(DTP) was from 11.86% to 86.13%, with mean value of 59.65%. w(WA-P_i), w(PA-P_i), w(Fe/Al-P_i), w(WA-P_o) and w(PA-P_o) had significant positive correlations with ρ(DTP) in the pore water, and w(Ca-P_i) was positively associated with ρ(DTP), but there was not a significant positive correlation between w(NA-P_o) and ρ(DTP). Even the exogenous phosphorus was under effective control, the possibility for IP and OP with a high activity in sediments to keep the lake in eutrophic state still exists.