巢湖沉积物-水界面磷酸盐释放通量研究

采用现场采样与室内测试方法,对调水后巢湖沉积物-水界面磷酸盐释放通量进行了研究。结果表明,夏季巢湖表层水、底层水、间隙水磷酸盐浓度变化范围分别为0.02～0.16、0.02～0.17、0.01～0.08mg.L-1,均值分别为（0.03±0.04）、（0.04±0.04）mg.L-1和（0.03±0.02）mg.L-1。秋季6个取样点表层水、底层水磷酸盐含量的变化范围均为0.03～0.06mg.L-1,均值为（0.04±0.04）mg.L-1,显著高于夏季对应样点浓度。而秋季间隙水磷酸盐浓度平均值为（0.015±0.003）mg.L-（1变化范围0.01～0.02mg.L-1）,与夏季对应样点相比差异不显著。夏季沉积物-水界面磷酸盐释放通量的变化范围为-27.46～6.27μgP.m-.2d-1,平均值为-1.54μgP.m-.2d-1。秋季磷酸盐释放通量变化范围为-10.61～-3.77μgP.m-.2d-1,均值为-6.19μgP.m-.2d-1,与夏季对应样点释放通量差异显著（α=0.05,P=0.002）。情景模拟表明,排除外源污染的影响,当引入长江水磷酸盐浓度介于0.003～0.009mg.L-1时,巢湖调水后替换水体可在7.2a左右达二次富营养化。

Benthic Flux of Phosphate Across Sediment-water Interface in Lake Chaohu

This research was performed in Lake Chaohu,aimed to estimate the benthic flux of phosphate across sediment-water interface.Results showed that concentrations of phosphate in surface,overlying and sediment interstitial water varied from 0.02 to 0.16（with mean value of 0.03 ± 0.04）,0.02 to 0.17（with mean value of 0.04±0.04）,and 0.01 to 0.08（with mean value of 0.03±0.02）mg·L-1,respectively in the summer of 2008.While concentrations of phosphate in both surface and overlying water varied from 0.03 to 0.06 mg·L-1,with average values of 0.04±0.04 mg·L-1 in the autumn of 2008.Phosphate concentrations in surface and overlying water showed no significant differences between summer and autumn observations.However,mean phosphate concentrations in interstitial water was 0.01 mg·L-1（0.01~0.02 mg·L-1） in autumn,significantly lower than those in summer.Benthic flux of phosphate ranged between-27.46 and 6.27 μgP·m-2·d-1 and averaged-1.54 μgP·m-2·d-1 in the summer,significantly different with that in the autumn（from-10.61 to-3.77 μgP·m-2·d-1,mean-6.19 μgP·m-2·d-1）（α=0.05,P=0.002）.In addition,we estimated that,excluding the influence of external pollution,Lake Chaohu would be eutrophic within 7.2 years after the project of water transportation from the Changjiang River to Lake Chaohu was carried out,when the concentration of phosphate in the transported water ranges between 0.003 mg·L-1 and 0.009 mg·L-1.