Natural background level, source apportionment and health risk assessment of potentially toxic elements in multi-layer aquifers of arid area in Northwest China

• Published in: Journal of hazardous materials Vol. 479; p. 135663
• Main Authors: Yao, Rongwen, Zhang, Yunhui, Yan, Yuting, Wu, Xiangchuan, Uddin, Md Galal, Wei, Denghui, Huang, Xun, Tang, Lijun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.11.2024
• Subjects: China; Environmental Monitoring; Groundwater - analysis; Groundwater - chemistry; Health Risk Assessment; Humans; Monte-Carlo Simulation; Natural Background Level; Positive Matrix Factorization; Potentially Toxic Elements; Risk Assessment; Water Pollutants, Chemical - analysis; China; Positive Matrix Factorization; Potentially Toxic Elements; Natural Background Level; Health Risk Assessment; Monte-Carlo Simulation
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.135663

Groundwater contaminated by potentially toxic elements has become an increasing global concern for human health. Therefore, it is crucial to identify the sources and health risks of potentially toxic elements, especially in arid areas. Despite the necessity, there is a notable research gap concerning the sources and risks of these elements within multi-layer aquifers in such regions. To address this gap, 54 phreatic and 24 confined groundwater samples were collected from an arid area in Northwest China. This study aimed to trace the sources and evaluate the human health risks of potentially toxic elements by natural background level (NBL), positive matrix factorization (PMF) model, and health risk model. Findings revealed exceeding levels of potentially toxic elements existed in phreatic and confined aquifers. Source apportionment and NBL results indicated that mineral dissolution, evaporation, redox reactions, and human activities were the main factors for elevated concentrations of potentially toxic elements. High Fe and Mn concentrations were attributed to reduction environments, while F accumulation resulted from slow runoff, and irrigation from the Yellow River. Due to high F levels, more than one-third of groundwater samples (phreatic: 33.14 %, confined: 56.22 %) posed non-carcinogenic health risks to population groups. Adults displayed higher carcinogenic risks (phreatic: 19.47 %, confined: 34.16 %) than infants (phreatic: 0 %, confined: 0 %) and children (phreatic: 1.26 %, confined: 7.97 %) owing to the toxic elements of Cr. The confined aquifer presented greater health risks than the phreatic aquifer. Consequently, controlling the levels of F and Cr in multi-layered aquifers is key to reducing health risks. These findings provide valuable insights into protecting groundwater from contamination by potentially toxic elements in multi-layered aquifers worldwide. [Display omitted] •NBLs and TVs indicated F, Al, Cr, Mn, and Fe exceed the drinking permission limits.•Three sources of potentially toxic elements were identified by PMF model.•Over one-third of groundwater samples posed non-carcinogenic health risks in all populations.•F and Cr were the most sensitive variables affecting human health risk.