Soils irrigated with wastewater are by and large contaminated with heavy metals, and consumption of vegetables and animal feed grasses grown in contaminated soils have been a major food chain route for human exposure and pose a health hazard. A study was conducted in three sites to assess the accumulation of heavy metals in farms irrigated with wastewater between two and five decades in and around Asmara, Eritrea. The concentrations of metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, V, and Zn) in soils and plants (Medicago sativa L., Avena sativa L., Cynodon dactylon L., Corchorus olitorius L., and Cynara scholymus L.) grown in the farms were analyzed using an inductively coupled plasma optical emission spectrophotometer (ICP-OES). Multivariate analysis, such as principal component analysis (PCA) and cluster analysis (CA), was performed on the distribution of elements in plant species to identify the source of the heavy metals. The level of the metals in the soil samples was in the order of Mo < Cd < Co < Cu < Pb < V < Cr ≈ Zn < Mn < Fe < Al. The order of the metals in the plants of the different sites has been, in general, Cd < Co < V < Cr < Pb < Cu < Zn < Mn < Al < Fe. The study revealed that the soil samples of the studied sites were unsafe for agricultural purposes with respect to Fe, Mn, and Pb except for Pb in the case of the soil sample from the Kushet area. The levels of most of the studied heavy metals in the vegetation samples from all the sites were found within the FAO/WHO permissible limit. Al and Fe exceeded the FAO/WHO permissible limit with the exception of all plant samples from the Kushet area and M. sativa from Paradizo. The concentration of Al was also below the limit in C. dactylon from Adi-Segdo and Paradizo. Of the five vegetation considered in this study, C. olitorius was found to be a good accumulator and C. dactylon, the lowest accumulator of heavy metals. Based on the results of this study, the grass species C. olitorius should be further investigated for its phytoremediation capability of contaminated soils. The results of the multivariate analysis revealed that Fe, V, Al, Cr, Co, and Pb were controlled by mixed (natural and anthropogenic) sources and Zn, Mo, Cu, Mn, and Cd originated from the anthropogenic source. Very limited and inadequate studies were conducted on the accumulation of heavy metals in plants grown in wastewater irrigated farms around Asmara. Therefore, the results of this study are expected to shed light on the understanding of the community and enable the City Council to monitor the environmental quality and take appropriate actions.

中文翻译：

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厄立特里亚阿斯马拉附近废水灌溉区种植的部分蔬菜和动物饲料草的重金属污染水平

用废水灌溉的土壤大体上受到重金属污染，食用在受污染土壤中生长的蔬菜和动物饲料已成为人类暴露的主要食物链途径，并对健康构成危害。在三个地点进行了一项研究，以评估厄立特里亚阿斯马拉及其周边地区在 2 到 50 年间用废水灌溉的农场中重金属的积累情况。土壤和植物（Medicago sativa L.、Avena sativa L.、Cynodon dactylon L.、Corchorus olitorius）中金属（Al、Cd、Co、Cr、Cu、Fe、Mn、Mo、Pb、V 和 Zn）的浓度L. 和 Cynara scholymus L.) 使用电感耦合等离子体发射分光光度计 (ICP-OES) 进行分析。多变量分析，如主成分分析（PCA）和聚类分析（CA），对植物物种中元素的分布进行了分析，以确定重金属的来源。土壤样品中金属的含量顺序为 Mo < Cd < Co < Cu < Pb < V < Cr ≈ Zn < Mn < Fe < Al。不同地点植物中金属的排列顺序一般为 Cd < Co < V < Cr < Pb < Cu < Zn < Mn < Al < Fe。研究表明，除了来自库舍特地区的土壤样品中的铅外，所研究地点的土壤样品中的铁、锰和铅对于农业用途是不安全的。来自所有地点的植被样本中大多数研究的重金属含量都在粮农组织/世卫组织允许的限度内。除了来自 Kushet 地区的所有植物样本和来自 Paradizo 的 M. sativa 之外，Al 和 Fe 超过了粮农组织/世卫组织的允许限量。来自 Adi-Segdo 和 Paradizo 的 C. dactylon 中的 Al 浓度也低于限值。在本研究中考虑的五种植被中，发现 C. olitorius 是一种很好的重金属累积剂，而 C. dactylon 则是最低的重金属累积剂。基于本研究的结果，应进一步研究草种 C. olitorius 对污染土壤的植物修复能力。多变量分析结果表明，Fe、V、Al、Cr、Co 和 Pb 受混合（天然和人为）来源控制，而 Zn、Mo、Cu、Mn 和 Cd 则来源于人为来源。对阿斯马拉周围废水灌溉农场种植的植物中重金属积累的研究非常有限且不充分。因此，本研究的结果有望阐明社区的理解，并使市议会能够监测环境质量并采取适当的行动。