风浪扰动中太湖OA对水体磷循环影响的原位实验研究

Effects of Wind-Induced Wave on Organic Aggregates Physical and Chemical Characteristics in a Shallow Eutrophic Lake(Lake Taihu) in China

在一次风速12 m.s-1的强风浪过程中,对太湖梅梁湾一浅水区水体有机聚集体(organic aggregates,OA)丰度、颗粒态有机质含量、碳、氮和磷含量等基本理化性质的变化情况进行了连续的原位监测和分析,同时分析了基本的水质指标.结果表明,风浪过程会对水体OA的理化性质及水体的磷循环产生极大的影响:在风浪过程中,OA丰度出现显著的增加,达到316.87mg.L-1,为无风时期均值的29倍;虽然在此过程中,水柱中以OA形式存在的营养盐总量出现了显著的增加,但同时OA丰度也出现了显著的上升,水体OA中颗粒态碳、氮和磷等营养元素浓度都出现了下降,下降幅度都超过50%;由于风浪扰动引起了沉积物悬浮,水体总悬浮颗粒物(SS)、总氮(TN)和总磷(TP)的浓度出现了显著的增加,达到325.5、9.43和0.242mg.L-1,分别为无风期的17.5倍、1.8倍和2.8倍.但是溶解态营养盐如溶解性总氮(TDN)、溶解性总磷(TDP)、溶解性反应磷(SRP)等的浓度却没有出现明显的上升;风浪过程中沉积物的再悬浮导致水体OA碱性磷酸酶活性和OA可酶解磷含量都出现明显的增加,最高达到0.005 9μmol.(L.min)-1,可见风浪扰动加速了OA磷的矿化速率和水柱中SRP的供给补偿;风浪过后,OA丰度、OA碱性磷酸酶活性、OA可酶解磷、水体SS、TN和TP等指标均出现了显著的回落并逐步达到了风浪前的水平.这说明风浪扰动引起的水体SRP释放可能并不是SRP直接由沉积物暴发性释放,而是水体颗粒态磷(尤其是OA磷)酶解并向水柱缓慢的连续性释放.

The physical and chemical characteristics were continually monitored during a wind course one time per day,which continued for 10 days,and other water physical and chemical parameters were concomitantly monitored.Organic aggregates（OA） abundance was significantly higher during wind period than calm stage and the maximum of OA abundance,which occurred the same day when wind speed was highest,was 29 times higher than that in the calm stage.Although OA-C,OA-N and OA-P concentration were decreased during wind period,the total C,N and P contend in OA were increased for the increased OA abundance.Additionally,suspended soil（SS）,total nitrogen（TN） and total phosphorus（TP） concentration during wind period were significantly higher than that of clam stage,but total dissolved phosphorus（TDP）,total dissolved nitrogen（TDN） and soluble reactive phosphorus（SRP） were insignificantly different.During the wind,OA alkaline phosphatase activity（OA-APA） and OA enzymatically hydrolyzable phosphorus（OA-EHP） both increased significantly,which accelerated organic phosphorous mineralization and SRP release.The results indicate that SRP release induced by wind in shallow lakes may comes from suspended matter,especially OA release rather than directly comes from sediment.