Abstract

Following the high rate at which many drinking water sources are polluted globally, an adequate evaluation of the potential hazards posed by polluted water systems is essential. In Nnewi urban (southeastern Nigeria), inhabitants indiscriminately dispose municipal solid wastes into streams and rivers, thereby exposing the surface water quality to deterioration. The aim of this study was to assess the pollution status, ecological risks, and probabilistic health risks of surface waters in this area using integrated study approach. Several heavy metal pollution indices used in this study showed that the waters generally have low pollution. However, Pb was identified as the priority pollutant. Ecological risk assessment revealed that the samples pose low ecological risk. Furthermore, non-carcinogenic risk assessment revealed low chronic risk; but children are more exposed to chronic risk due to ingestion than adults. However, with respect to dermal contact, all the samples pose negligible risks to both populations, as their hazard indices were <0.1. The probability of cancer risk, when compared to the acceptable range of ≤1 × 10⁻⁶ to 1 × 10⁻⁴, revealed that many of the samples pose carcinogenic risk due to Pb ingestion to adults (75%) and children (100%). However, all the samples pose negligible cancer risk due to dermal contact. Water quality index revealed that majority (75%) of the samples are poor quality water, and thus not recommended for drinking purpose. Correlation and factor analyses showed that both geogenic and anthropogenic factors influence the presence of the analytes in the surface waters.

摘要

随着全球许多饮用水源的高污染率，对受污染的水系统造成的潜在危害进行充分评估至关重要。在 Nnewi 城市（尼日利亚东南部），居民不分青红皂白地将城市固体废物排放到溪流和河流中，从而使地表水质量恶化。本研究的目的是采用综合研究方法评估该地区地表水的污染状况、生态风险和概率性健康风险。本研究中使用的多项重金属污染指数表明，该水域总体污染程度较低。然而，铅被确定为优先污染物。生态风险评估显示，样本的生态风险较低。此外，非致癌风险评估显示慢性风险较低；但儿童比成人更容易因摄入而面临慢性风险。然而，就皮肤接触而言，所有样本对两个人群的风险都可以忽略不计，因为它们的危害指数<0.1。与 ≤1 × 10 的可接受范围相比，癌症风险的概率^-6到 1 × 10 ^-4显示，由于铅摄入成人（75%）和儿童（100%），许多样品具有致癌风险。然而，由于皮肤接触，所有样本的癌症风险都可以忽略不计。水质指标显示，大部分（75%）样本为劣质水，因此不建议饮用。相关性和因素分析表明，地质和人为因素都会影响地表水中分析物的存在。