Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, Enugu State, Nigeria E-mail:
J Water Health. 2022 Jun;20(6):927-945. doi: 10.2166/wh.2022.003.
The study determined the following heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) concentrations in surface water and in fish pond (water, sediments and farmed fish (Clarias gariepinus)) from a fish farm cluster with the view of assessing its pollution level and associated human health exposure risk to these heavy metals through fish consumption. Samples were digested with aqua regia and metal concentrations were determined with an atomic absorption spectrophotometer equipped with an air acetylene flame. Mean concentrations of the heavy metals (ppm) in surface and pond water ranged as follows: cadmium (below detection limit (bdl): 0.298); chromium (bdl: 0.257); copper (bdl: 0.067); manganese (bdl: 0.163); lead (bdl: 0.736) and zinc (bdl: 0.078) while in sediment, the ranges (mg/kg dry weight) were as follows: cadmium (1.156-3.329); chromium (9.439-14.373); copper (26.710-121.819); manganese (3.143-37.202); lead (0.340-1.537) and zinc (87.681-371.060). The mean concentrations of the metals in surface water were significantly different (p < 0.05) from those in sediment in all the sampling sites. The mean metal concentrations (mg/kg dry weight) in C. gariepnus were in the following ranges: cadmium (0.733-1.405); chromium (0.593-1.692); copper (175.882-245.321); manganese (bdl: 3.326); lead (0.221-0.263) and zinc (248.191-292.333). Some of the heavy metal concentrations obtained in water, sediment and catfish analyzed were above the permissible limit set by some National (DPR) and International organisations (WHO, FEPA and FAO). The pollution studies showed that lead, cadmium and chromium contaminated the surface water samples. Sediment from all sites showed low to considerable contamination by the heavy metals. The human exposure risk assessment of the metals showed that the total hazard index was less than one which indicates no probable adverse health effect from the consumption of fish from the ponds, although this case is different for Pb since there is no estimation of oral reference dose (RfDo) for lead according to EPA.
该研究确定了养殖场集群中地表水和鱼塘（水、沉积物和养殖的鱼类（Clarias gariepinus））中的以下重金属浓度：镉（Cd）、铬（Cr）、铜（Cu）、锰（Mn）、铅（Pb）和锌（Zn），目的是评估其污染水平以及通过鱼类消费接触这些重金属对人类健康的潜在风险。使用 Aqua regia 对样品进行消解，并用配备空气乙炔火焰的原子吸收分光光度计测定金属浓度。地表水和池塘水中重金属的平均浓度（ppm）如下：镉（低于检测限（bdl）：0.298）；铬（bdl：0.257）；铜（bdl：0.067）；锰（bdl：0.163）；铅（bdl：0.736）和锌（bdl：0.078）；而在沉积物中，范围（mg/kg 干重）如下：镉（1.156-3.329）；铬（9.439-14.373）；铜（26.710-121.819）；锰（3.143-37.202）；铅（0.340-1.537）和锌（87.681-371.060）。所有采样点的地表水和沉积物中金属的平均浓度（p<0.05）均存在显著差异。C. gariepnus 中的金属平均浓度（mg/kg 干重）范围如下：镉（0.733-1.405）；铬（0.593-1.692）；铜（175.882-245.321）；锰（bdl：3.326）；铅（0.221-0.263）和锌（248.191-292.333）。分析的水中、沉积物和鲶鱼中的一些重金属浓度超过了一些国家（DPR）和国际组织（世卫组织、FEPA 和粮农组织）设定的允许限值。污染研究表明，地表水样品受到铅、镉和铬的污染。所有地点的沉积物均受到重金属的低至高程度的污染。金属的人类暴露风险评估表明，总危害指数小于一，这表明从池塘中鱼类消费中可能没有不良健康影响，尽管对于 Pb 情况有所不同，因为根据 EPA，没有估计铅的口服参考剂量（RfDo）。
