Identification of metal ligands and their producers affecting ecosystem in Lake Biwa

采用伪极谱法研究了淡水中铜的“强”配体检测。将该方法应用于琵琶湖北部盆地和Teganuma湖的淡水采样。琵琶湖地表水中检测到EDTA等强配体，1m和15m采样水域中检测到logK估计在30左右的强配体。通过对Teganuma湖的水进行分析，在取样过滤后立即添加铜。在这种情况下，存在在赝极谱还原电位范围内未检测到的强配体。24小时后对加入铜的同一水进行分析时，没有清楚地观察到这一现象。这一事实表明存在不稳定的和非常强的配体，如硫化物。

Detection of "strong" ligand for copper in freshwater was investigated by pseudopolarography. This method was applied to freshwaters sampled in north basin of Lake Biwa and Lake Teganuma. In surface water of Lake Biwa, strong ligand like EDTA was detected, while highly strong ligand that was estimated to have logK around 30 was detected in waters sampled at 1m and 15m.By analyzing water of Lake Teganuma, copper was added immediately after sampling and filtration. In this case, existence of very strong ligand that was not detected within the range of reduction potential applicable in pseudopolarography was suggested. This phenomenon was not clearly observed by analysis of the same water in which copper was added 24hrs later. This fact suggests the existence of labile and very strong ligand like sulfide.