Campbell L M, Osano O, Hecky R E, Dixon D G
University of Waterloo, 200 University Avenue, N2L 3G1, Waterloo, ON, Canada.
Environ Pollut. 2003;125(2):281-6. doi: 10.1016/s0269-7491(03)00053-8.
Total mercury (THg) concentrations were measured for various fish species from Lakes Turkana, Naivasha and Baringo in the rift valley of Kenya. The highest THg concentration (636 ng g(-1) wet weight) was measured for a piscivorous tigerfish Hydrocynus forskahlii from Lake Turkana. THg concentrations for the Perciformes species, the Nile perch Lates niloticus from Lake Turkana and the largemouth bass Micropterus salmoides from Lake Naivasha ranged between 4 and 95 ng g(-1). The tilapiine species in all lakes, including the Nile tilapia Oreochromis niloticus, had consistently low THg concentrations ranging between 2 and 25 ng g(-1). In Lake Naivasha, the crayfish species, Procambrus clarkii, had THg concentrations similar to those for the tilapiine species from the same lake, which is consistent with their shared detritivore diet. THg concentrations in all fish species were usually consistent with their known trophic position, with highest concentrations in piscivores and declining in omnivores, insectivores and detritivores. One exception is the detritivore Labeo cylindricus from Lake Baringo, which had surprisingly elevated THg concentrations (mean=75 ng g(-1)), which was similar to those for the top trophic species (Clarias and Protopterus) in the same lake. Except for two Hydrocynus forskahlii individuals from Lake Turkana, which had THg concentrations near or above the international marketing limit of 500 ng g(-1), THg concentrations in the fish were generally below those of World Health Organization's recommended limit of 200 ng g(-1) for at-risk groups.
对肯尼亚裂谷地区图尔卡纳湖、奈瓦沙湖和巴林戈湖的各种鱼类进行了总汞（THg）浓度测量。在图尔卡纳湖捕获的食鱼性虎鱼（Hydrocynus forskahlii）的总汞浓度最高（湿重为636纳克/克）。图尔卡纳湖的鲈形目鱼类尼罗尖吻鲈（Lates niloticus）和奈瓦沙湖的大口黑鲈（Micropterus salmoides）的总汞浓度在4至95纳克/克之间。所有湖泊中的罗非鱼种类，包括尼罗罗非鱼（Oreochromis niloticus），总汞浓度一直较低，在2至25纳克/克之间。在奈瓦沙湖，克氏原螯虾（Procambrus clarkii）的总汞浓度与来自同一湖泊的罗非鱼种类相似，这与它们共同的碎屑食性一致。所有鱼类的总汞浓度通常与其已知的营养级位置一致，食鱼动物中的浓度最高，杂食动物、食虫动物和碎屑食性动物中的浓度逐渐降低。一个例外是来自巴林戈湖的碎屑食性鱼类圆筒唇鲮（Labeo cylindricus），其总汞浓度惊人地升高（平均为75纳克/克），与同一湖泊中顶级营养级物种（胡子鲶属和非洲肺鱼属）的浓度相似。除了来自图尔卡纳湖的两条虎鱼个体，其总汞浓度接近或高于500纳克/克的国际销售限值外，鱼类中的总汞浓度一般低于世界卫生组织针对高危人群建议的200纳克/克限值。
