Faculty of Agriculture, Yamagata University, 1-23 Wakaba-machi, Tsuruoka, Yamagata, 997-8555, Japan.
Faculty of Agriculture, Gadjah Mada University, Bulaksumur, Yogyakarta, 55281, Indonesia.
Environ Pollut. 2021 Jun 1;278:116813. doi: 10.1016/j.envpol.2021.116813. Epub 2021 Mar 8.
This study focused on the seasonal variation and source identification of heavy metals (HMs) while considering effects of municipal wastewater (MWW) in peri-urban farms of Hue city, central Vietnam. Moreover, associated non-carcinogenic and carcinogenic health risks from consuming vegetables containing HMs were also assessed considering the hazard quotient and cancer risk, respectively. Therefore, concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb, and As were determined in irrigation water, soil, and lettuce samples collected during dry and wet seasons from one upstream site where irrigation water has no impact on MWW as well as from two downstream sites in farms on the outskirt of the city. Although irrigation water and soil in the same farms were not polluted as strongly, lettuce samples were polluted with Cd, Zn, and Pb. Furthermore, levels of soil Cu and As and HMs (except for Cu) in lettuce in the wet season were significantly higher (p < 0.05) than those in the dry season, indicating the impact of MWW with seasonal change. The health risk assessment via lettuce consumption demonstrated an unacceptable carcinogenic risk owing to Cd and a cumulative non-carcinogenic risk owing to selected HMs in the lettuce, while all other risks were negligible. Correlation and principal component analyses were performed to identify HM sources, indicating that Cu, Zn, Cd, Pb, Cr, and As in irrigation water and soil could have anthropogenic sources (e.g., untreated MWW, fertilizer use); meanwhile, irrigation-water and soil Fe, Mn, As, and Cr could originate from non-anthropogenic sources (e.g., parent materials weathering). This study revealed that rapid urbanization together with high precipitation leading to urban floods in Hue city was a significant factor spreading HMs in agricultural farms, suggesting the importance of wastewater treatment system, which can reduce the HM load in the city to protect the local food production.
本研究关注重金属（HMs）的季节性变化和来源识别，同时考虑到越南中部 Hue 市周边农场中城市污水（MWW）的影响。此外，还分别考虑了危害系数和癌症风险，评估了食用含 HM 蔬菜的非致癌和致癌健康风险。因此，在旱季和雨季，从一个上游站点（灌溉水不受 MWW 影响）以及城市郊区的两个下游农场采集灌溉水、土壤和生菜样本，测定 Fe、Mn、Zn、Cu、Cr、Cd、Pb 和 As 的浓度。尽管同一农场的灌溉水和土壤没有受到那么强烈的污染，但生菜样本受到了 Cd、Zn 和 Pb 的污染。此外，雨季土壤 Cu 和 As 以及生菜中的除 Cu 以外的其他 HM 水平（p<0.05）显著高于旱季，表明 MWW 随季节变化的影响。通过食用生菜进行健康风险评估表明，由于 Cd 存在不可接受的致癌风险，以及由于生菜中选择的 HM 存在累积非致癌风险，因此存在风险，而其他所有风险都可以忽略不计。相关性和主成分分析用于识别 HM 来源，表明灌溉水和土壤中的 Cu、Zn、Cd、Pb、Cr 和 As 可能具有人为来源（例如，未经处理的 MWW、肥料使用）；同时，灌溉水和土壤中的 Fe、Mn、As 和 Cr 可能来自非人为来源（例如，母质风化）。本研究表明，Hue 市快速城市化和高降水导致城市洪水泛滥，这是导致农业农场中 HM 扩散的一个重要因素，这表明废水处理系统的重要性，该系统可以减少城市中的 HM 负荷，以保护当地的粮食生产。
