南太行典型区小流域土壤铅含量空间分异及影响因素分析

为揭示小流域尺度土壤铅（Pb）含量的空间分异规律及影响机制,提高土壤污染修复与管控效率。该研究以蟒河小流域为研究区,采集121份土壤表层（0～20 cm）样品和15份环境辅助样品,利用经典统计学、地统计学和地理探测器等模型方法对土壤Pb空间分异特征及其影响因素展开研究。结果表明：1）蟒河小流域土壤Pb含量的平均值为110.40 mg/kg,高于区域背景值,部分点位超过农用地土壤污染风险筛选值,存在污染风险;2）土壤Pb含量变异程度为强变异,且不同方向均存在较强的变异程度,南-北（0°）和东北-西南（45°）变异在空间变异中占主导作用,变异程度受成土母质、地形等结构性因素影响大。3）经验贝叶斯克里金空间插值显示土壤Pb含量整体由西南向东北带状逐步增加,局部特征明显,东北部山前平原和中部平原区域是土壤Pb污染风险监测的重点区;4）地质类型和土地利用对土壤Pb含量空间分布差异具有最强解释力,叠加距矿山距离和工业距离等因素后,其交叉作用影响程度显著增加,地质地形、大气等自然因素叠加工矿企业及农业生产等复杂环境下区域重金属污染综合研究是未来面临并需要研究的重要内容。该研究可为南太行典型区复杂环境下土壤重金属污染防治与修复治理提供精准支撑。

Spatial differentiation and influencing factors analysis of Pb in soils in the small watershed of typical area in the Southern Taihang Mountains

Heavy metal pollution has been one of the most significant concerns on the soil environmental quality for the Taicang agricultural sustainability and human health. It is of paramount importance to analyze the spatial variations and influencing factors of regional distribution in the soil heavy metal. Among them, the Manghai River watershed is nestled within a typical ecological zone in the southern Taihang region. Rapid socioeconomic development has also been experienced by the convergence of industries, such as non-ferrous metal smelting, coal coking, and mining. Soil environmental pollution is also coupled with the unique terrain and topographical features, especially heavy metal pollution, notably lead (Pb) and cadmium (Cd). Much attention has been gained to prevent and control the soil heavy metal pollution in this region. This study aims to unveil the spatial variation patterns and influencing mechanisms of soil Pb content at the scale of the Manghai River watershed. The sampling points were employed as a 1 km×1 km grid using high-resolution remote sensing imagery and land use data. A total of 121 topsoil samples (0-20 cm) and 15 environmental auxiliary samples were collected, including 5 surface water samples, 5 dust samples, and 5 sediment samples. The classic statistical methods, geostatistics, and geographic detectors were utilized to probe the spatial variation characteristics of soil Pb content and their influencing factors. Results were as follows: 1) Soil Pb content was relatively high with an average of 110.40 mg/kg, particularly over the regional background values. Notably, the soil Pb content exceeded the threshold to identify the soil pollution risk at some locations in the agricultural land, indicating the sever contamination risks; 2) There was an outstanding variation in the soil Pb content across the study area, with the marked variances in various directions. The spatial patterns were dominated in the variability along the south-north (0°) and northeast-southwest (45°) axes, indicating the influence of structural factors, such as the parent material and terrain; 3) Empirical Bayesian kriging spatial interpolation showed that there was a gradual, belt-like increase in the soil Pb content from the southwest to the northeast, indicating the distinct local features. The northeastern foothill plain and central plain areas emerged as the focal points to monitor and control the soil Pb pollution risks; 4) Geological type and land use were the primary determinants of spatial distribution differences in the soil Pb content. The combined influence significantly heightened the impact of factors, like proximity to the mines and industries. Therefore, a comprehensive investigation can be preferred on the regional heavy metal pollution within the complex environments, including the geological and topographical factors, natural elements, such as atmospheric conditions, and complex interactions with industrial and agricultural activities. There was also the spatial heterogeneity of distribution patterns in the soil heavy metal pollution using watershed units. The spatial distribution and influencing factors of soil Pb pollution can provide precise support to the prevention, control, and remediation of soil heavy metal pollution under the complex environment of the southern Taihang region.