摘要
过去流入维纳恩湖的含汞废水颇多。通过连续测定沉积物和鱼体中的汞来监测其影响和恢复状况。汞的主要源头来自湖北岸的一座氯碱工厂。尽管60年代从源头流出的废水中汞水平有了根本性的减少。附近湖泊沉积物中汞的水平从70年代中期以来只下降了一半多。狗鱼(Esoxlucius)体内汞的水平在同期下降的幅度相似。湖泊受影响最大的部分比受影响最小的部分要高出30%。湖泊中的鲈鱼(Percafluviatilis)和三文鱼鱼体内汞水平不高。尽管维纳恩湖沉积物中汞水平有所增加,比起位于同一地区而没有受当地汞废水污染湖泊内的鱼来说,维纳恩湖鱼体内汞的水平相对来说并不算高。据估算,湖内鱼类总生物量所含的汞不到湖泊底部沉积物上层活性生物层所含汞总量的千分之一。这显示了各种环境因子的潜在影响,并促使我们将来要继续对汞水平进行监测。
The past effluents of mercury (Hg) into Lake Vanern were considerable. The consequences of, and recovery from these have been monitored through continuous measurements of mercury in sediment and fish. Mercury levels in lake sediments in the vicinity of the main source of mercury, a chloralkali plant on the northern shore, have only decreased by slightly more than a half since the mid-1970s, despite a radical decrease in effluents from the source, already during the 1960s. The mercury levels in pike (Esox lucius) have decreased to a similar extent during this time period. They are now about 30% higher in the worst affected parts of the lake compared to the least affected parts. Lower levels have been measured in perch (Perca fluviatilis) and salmonoid fish in the lake. Despite the increased presence of mercury in the sediment of Lake Vanern, the mercury levels in the fish of the lake are relatively low compared to fish in lakes situated in the same region, but not affected by any local mercury effluents. As calculated, the total fish biomass of L. Vanern holds less than 1000th of the amount of mercury contained in the upper, biologically active layers of the bottom sediment of the lake. This demonstrates the potential influence of various environmental factors and motivates continued monitoring of mercury levels in the lake in the future.
