Wang Liling, Eziz Mamattursun, Hu Yonglong, Subi Xayida
College of Geographical Science and Tourism, Xinjiang Normal University, Urumqi 830054, China.
Laboratory of Arid Zone Lake Environment and Resources, Xinjiang Normal University, Urumqi 830054, China.
Toxics. 2024 Jul 3;12(7):488. doi: 10.3390/toxics12070488.
Heavy metal(loid) (HM) contamination is a significant threat to wetland ecosystem. However, contamination risks of HMs in overlying water of small wetlands, which are easily ignored because of their minor occupancy in an overall area, are nearly unknown. A total of 36 water samples containing six HMs were collected from the urban and rural small wetlands of Urumqi in China, and the contamination levels and probabilistic health risks caused by HMs were assessed using the Nemerow pollution index (NPI) and the health risk assessment model introduced by the US EPA. The results revealed that the average concentration of Hg in the urban and rural small wetlands surpassed the Class II thresholds of the Environmental Quality Standards for Surface Water (GB 3838-2002) by factors of 3.2 and 5.0 times, respectively. The overall contamination levels of HMs in the small wetlands fall into the high contamination level. Results of a health risk assessment indicated that non-carcinogenic health risk of the investigated HMs are found to be lower than the acceptable range for adults, but higher than the acceptable range for children. Meanwhile, As falls into the low carcinogenic risk level, whereas Cd falls into the very low carcinogenic risk level. Overall, HMs in rural small wetlands showed relatively higher contamination levels and probabilistic health risks than that of urban small wetlands. In addition, As was identified as the dominant health risk factor in the overlying water of small wetlands in the study area. Findings of this study provide scientific support needed for the prevention of HM contamination of small wetlands in arid zones.
重金属（类金属）（HM）污染是对湿地生态系统的重大威胁。然而，小型湿地覆盖水中重金属的污染风险因在总面积中占比小而容易被忽视，目前几乎无人知晓。在中国乌鲁木齐的城乡小型湿地共采集了36份含六种重金属的水样，并采用内梅罗污染指数（NPI）和美国环境保护局引入的健康风险评估模型评估了重金属造成的污染水平和概率健康风险。结果显示，城市和农村小型湿地中汞的平均浓度分别超过了《地表水环境质量标准》（GB 3838 - 2002）二级标准限值的3.2倍和5.0倍。小型湿地中重金属的总体污染水平处于高污染级别。健康风险评估结果表明，所调查重金属的非致癌健康风险对成年人而言低于可接受范围，但对儿童而言高于可接受范围。同时，砷处于低致癌风险水平，而镉处于极低致癌风险水平。总体而言，农村小型湿地中的重金属污染水平和概率健康风险相对高于城市小型湿地。此外，砷被确定为研究区域小型湿地覆盖水中的主要健康风险因素。本研究结果为干旱地区小型湿地重金属污染防治提供了所需的科学支持。
