Huailiang Yu

Heavy metal pollution poses a significant threat to industrial and agricultural ecosystems; however, thorough research on the coupled risks and migration mechanisms of heavy metals within soil-groundwater systems in arid-region industrial parks remains limited. This study systematically collected 312 surface soil samples and 239 groundwater samples from typical chemical industrial parks in Xinjiang, northwestern China. The pollution levels of six typical heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) were quantitatively evaluated utilizing the Single Pollution Index (P_i), Nemerow Pollution Index (P_N), and Potential Ecological Risk Index (RI) for soil and the improved Heavy Metal Contamination Index (HCI) for groundwater. Additionally, GIS mapping and the Positive Matrix Factorization (PMF) model were integrated to delineate spatial distributions and primary emission sources. The assessment results indicated overall moderate pollution risks for Cd, Cu, and Ni in the soil, and for Cd, Pb, Cr, and Ni in the groundwater. Notably, Cd emerged as the primary risk contributor across both media. The RI identified Cd as the element posing the highest soil toxicity risk (with a mean RI of 53.57), while the HCI revealed that specific industrial zones face severe contamination levels (HCI > 4500), predominantly driven by Cd and Pb. GIS analysis illustrated a distinct distance–decay diffusion pattern emanating from industrial point sources. Crucially, PMF source apportionment demonstrated divergent contamination pathways: surface soil heavy metals (e.g., Cr, Cu, Pb, Zn) were primarily governed by top-down local industrial emissions (52.5%), whereas groundwater contamination was largely dictated by regional groundwater flow carrying mixed agricultural and natural geogenic inputs (75%). Furthermore, Pearson correlation analysis revealed a prevalent weak or negative correlation between heavy metal concentrations in the two media, suggesting a spatial “decoupling” of their contamination pathways. This phenomenon is likely driven by a dynamic “retention-leaching” mechanism within the arid vadose zone, where alkaline pH and high clay content act as a hydrochemical barrier impeding vertical migration. These findings underscore that soil and groundwater in arid industrial regions should be managed as distinct hydrochemical systems, providing a robust scientific basis for targeted remediation and the sustainable redevelopment of industrial brownfields.

As a core element of comprehensive land consolidation, cultivated land serves as both a fundamental resource and strategic platform for driving rural revitalization and advancing ecological civilization development. Based on the five periods of remote sensing monitoring data of land use from the 1980 to 2020 in Beichuan Qiang Autonomous County, this study systematically examines cultivated land transfer dynamics and quantitatively assesses fragmentation levels through landscape metrics analysis, with the ultimate objective of informing strategic land consolidation planning at the county scale. The results indicate that (1) the cultivated land transformation in Beichuan Qiang Autonomous County exhibited distinct temporal patterns demarcated by 2010. During the initial phase, limited land transfers predominantly involved woodland transfers, characterized by cross-regional occupation–compensation dynamics and a northwest-oriented spatial shift. The subsequent phase witnessed substantial transfer intensification, incorporating grassland and construction land transfers alongside woodland. This period demonstrated balanced intra-township occupation–compensation mechanisms and a marked southeastward migration of transfer concentration; (2) cultivated land transfer dynamics demonstrated greater intensity in topographically moderate townships, whereas northwestern mountainous townships characterized by elevated altitudes and pronounced gradients maintained comparative spatial stability in transfer patterns; (3) cultivated land fragmentation exhibited topographic modulation, with reduced spatial disaggregation in low-lying plains contrasting elevated indices across northwestern highland terrains; and (4) the cultivated land area showed a predominant reduction in low-elevation and gentle-slope regions, accompanied by a decrease in landscape fragmentation. Conversely, in areas with higher elevations and steeper slopes, expansions in both cultivated land area and fragmentation were observed.