Surface sediment samples were collected from different streams of Awetu Watershed in southwestern Ethiopia. Sediment samples were analyzed for As, Cd, Cr, Pb, and Hg levels using inductively coupled plasma optical emission spectrometry. The heavy metal concentration ranged from 183.60 to 1102.80 mg/kg for As (mean 623.32 ± 291.65 mg/kg), 4.40 to 303.20 mg/kg for Cd (151.09 ± 111.5 mg/kg), 149.20 to 807.20 mg/kg for Cr (375 ± 212.03 mg/kg), 485.60 to 3748.80 mg/kg for Pb (2005.94 ± 954.99 mg/kg) and 3.6 to 5.6 mg/kg for Hg (4.64 ± 0.59 mg/kg). The mean heavy metal concentration in the streams followed the decreasing order of Pb > As > Cr > Cd > Hg. As, Cr and Pb are detected at high concentrations with values of 623.32, 375.00, and 2,005.94 mg/kg respectively. A low level of heavy concentration (3.6 mg/kg) was recorded for Hg. The contamination factor (CF) of all the studied heavy metals ranged from a low degree (CF < 1) to a very high degree (CF ≤ 6). Mainly, Dololo and Kito streams show a very high degree of contamination (CF ≤ 6) than Awetu and Boye streams. Specifically, As, Cd, and Cr in the Dololo and Kito streams have significantly elevated concentrations than others. Geo-accumulation index (Igeo) shows low to moderate contamination level with As, Pb, and Hg; uncontaminated to heavily contaminated by Cr; and moderate to extreme contamination by Cd. Untreated solid waste, garages and farmlands were sources of contamination. Streams receiving wastewater effluents from teaching institutions had higher heavy metal concentrations. Dumping of electronic wastes and car washing discharges also identified as another source of pollution.

中文翻译：

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埃塞俄比亚西南部阿维图流域河流沉积物重金属污染

从埃塞俄比亚西南部的 Awetu 流域的不同河流收集表层沉积物样品。使用电感耦合等离子体发射光谱法分析沉积物样品中的 As、Cd、Cr、Pb 和 Hg 水平。重金属浓度范围为 As 183.60 至 1102.80 mg/kg（平均 623.32 ± 291.65 mg/kg），Cd 4.40 至 303.20 mg/kg（151.09 ± 111.5 mg/kg），149.20 mg/kg（平均 623.32 ± 291.65 mg/kg），149.20 mg/kg（平均 623.32 ± 291.65 mg/kg） 375 ± 212.03 mg/kg)，Pb 为 485.60 至 3748.80 mg/kg (2005.94 ± 954.99 mg/kg)，Hg 为 3.6 至 5.6 mg/kg (4.64 ± 0.59 mg/kg)。流中的平均重金属浓度遵循 Pb > As > Cr > Cd > Hg 的递减顺序。As、Cr 和 Pb 在高浓度下被检测到，分别为 623.32、375.00 和 2,005.94 mg/kg。记录到 Hg 的低浓度重浓度 (3.6 mg/kg)。所有研究的重金属的污染因子 (CF) 范围从低度 (CF < 1) 到非常高 (CF ≤ 6)。主要是，Dololo 和 Kito 溪流比 Awetu 和 Boye 溪流表现出非常高的污染程度 (CF ≤ 6)。具体而言，Dololo 和 Kito 流中的 As、Cd 和 Cr 的浓度明显高于其他流。地质累积指数 (Igeo) 显示 As、Pb 和 Hg 的低至中度污染水平；未受铬污染至严重污染；和中度到极端的 Cd 污染。未经处理的固体废物、车库和农田是污染源。接收来自教学机构的废水的溪流具有较高的重金属浓度。倾倒电子废物和洗车排放也被确定为另一个污染源。