Source Apportionment of Heavy Metals in Groundwater at a Chemical Industry Park in Southern China Based on the...

Heavy metal contamination of groundwater is a recognized problem in chemical industrial parks in China, however, the contaminant sources are complex and the related controlling processes remain poorly understood. In this study, a total of 127 groundwater samples were collected from a typical chemical industrial park in southern China, and 10 heavy metals, including Fe, Mn, Al, Pb, Cd, Tl, As, Co, Zn, and Ni, were analyzed. An integrated framework combining hydrochemical analysis, spatial distribution, self-organizing map (SOM), and positive matrix factorization (PMF) was applied to identify the contamination sources and controlling mechanisms. The groundwater in the study area was mainly of the Cl-Na, HCO₃-Na, and Cl-Ca·Mg types, with a wide range of TDS and a clear deviation from the regional natural hydrogeochemical evolution pathway, indicating substantial anthropogenic disturbance. Heavy metal showed strong spatial heterogeneity, with elevated concentrations mainly distributed in the central to north-central part of the study area. Fe-Mn and Co-Ni exhibited strong co-variation, whereas As was relatively independent. SOM identified five representative contamination patterns groups, and PMF further resolved five major source factors: acid-condition-driven mobilization of Fe-Mn geogenic metals (64%), followed by a mixed geogenic-anthropogenic source associated with Mn-Co-Ni source, a composite industrial source related to fluorochemical and metallurgical chemical activities, localized industrial inputs dominated by Pb-Al together with acidification-induced mobilization, and a source of As governed by natural background and hydrogeochemical processes. Overall, groundwater metal contamination in the study area was jointly controlled by anthropogenic inputs, hydrogeochemical conditions, and the geological background, with acid-driven hydrochemical disturbance being the dominant process. This study provides a basis for source identification and groundwater contamination control in chemical industrial parks.