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

研究了用伪极谱法测定淡水中铜的强配体。该方法适用于在北部盆地的琵琶湖和手沼湖淡水采样。在琵琶湖表层水中检测到EDTA等强配体，而在1m和15m处的沃茨中检测到logK约为30的强配体。在这种情况下，存在非常强的配体，没有检测到的范围内的还原电位适用于伪极谱法建议。通过分析24小时后加入铜的同一水中，没有清楚地观察到这种现象。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.