Oyewale A O, Musa I
Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.
Environ Geochem Health. 2006 Jun;28(3):273-81. doi: 10.1007/s10653-006-9043-3. Epub 2006 Apr 20.
The objective of this investigation was to examine the heavy metal status of the lower basin of Kainji dam (used for hydroelectricity generation), which includes Lakes Kainji/Jebba, Nigeria, and the potential for human exposure to heavy metals from eating fish caught in the lakes. Water, sediments and fish were sampled from the lakes and evaluated for As, Cu, Co, Cr, Fe, Hg, Mn, Ni, Pb, Sb, Ti, V and Zn using the EDXRF technique. Fe and Mn were found to be present at high mean concentrations in the water (13 and 9 microg L(-1)), sediment (7,092 and 376 microg g(-1)) and fish (11.4 and 4.6 microg g(-1)) samples. Sb (3.2 microg L(-1)), Ti (4.1 mug L(-1)), Cr (2.2 microg L(-1)), Co (1.2 microg L(-1)), Cu (1.3 microg L(-1)) and Pb (1.2 microg L(-1)) in the water samples and Sb (29 microg g(-1)), Ti (27 microg g(-1)), V (27 microg g(-1)), Cr (27 microg g(-1)), Co (40 microg g(-1)), Ni (33 microg g(-1)), Cu (25 microg g(-1)), Zn (59 microg g(-1)) and Pb (19 microg g(-1)) in the sediment samples were found to be of medium mean concentrations. The other metals were present at trace levels (<1 microg), including As and Hg in the fish and sediment samples. There was an appreciable increase in metal concentrations in going from the water to the sediment samples. The probable source of the pollutants is anthropogenic, arising from agricultural activities, corrosion/abrasion of the ferrous steel material and additives in the lubricants and insulation used for auxiliary services on the turbine floor of the dam constructed on the lakes. However, natural geological sourcing from the underlying lake rock cannot be totally ignored, particularly the high levels of Fe and Mn in the sediment samples. The potential risk for human exposure to these metals emanates from the fish caught in the lakes and subsequently consumed, as there are already significant levels of these metals in the two fish species analysed, Tilapia (Oreochromis niloticus) and Chrysicthys (Chrysicthys auratus).
本调查的目的是检测卡因吉大坝下游流域（用于水力发电）的重金属状况，该流域包括尼日利亚的卡因吉湖/杰巴湖，以及人类因食用在这些湖泊中捕获的鱼类而接触重金属的可能性。从这些湖泊采集了水、沉积物和鱼类样本，并使用能量色散X射线荧光光谱（EDXRF）技术对其中的砷、铜、钴、铬、铁、汞、锰、镍、铅、锑、钛、钒和锌进行了评估。结果发现，铁和锰在水样（分别为13和9微克/升）、沉积物样本（分别为7092和376微克/克）和鱼类样本（分别为11.4和4.6微克/克）中的平均浓度较高。水样中的锑（3.2微克/升）、钛（4.1微克/升）、铬（2.2微克/升）、钴（1.2微克/升）、铜（1.3微克/升）和铅（1.2微克/升），以及沉积物样本中的锑（29微克/克）、钛（27微克/克）、钒（27微克/克）、铬（27微克/克）、钴（40微克/克）、镍（33微克/克）、铜（25微克/克）、锌（59微克/克）和铅（19微克/克）的平均浓度处于中等水平。其他金属的含量处于痕量水平（<1微克），包括鱼类和沉积物样本中的砷和汞。从水样到沉积物样本，金属浓度有明显增加。污染物的可能来源是人为的，源于农业活动、大坝涡轮机层辅助服务所用的黑色钢铁材料的腐蚀/磨损以及润滑剂和绝缘材料中的添加剂。然而，来自湖底岩石的自然地质来源也不能完全被忽视，特别是沉积物样本中铁和锰的含量较高。人类接触这些金属的潜在风险源于在这些湖泊中捕获并随后食用的鱼类，因为在分析的两种鱼类罗非鱼（尼罗罗非鱼）和非洲胡鲇（金色胡鲇）中，这些金属已经有相当高的含量。
