Abstract：
The spatial diffusion mechanism underlying cropland heavy metal contamination in a complex peri-urban environment provides a crucial basis for controlling soil contamination from the source and also for ensuring the quality of black soil croplands. However, previous studies have struggled to locate the contamination sources or trace their diffusion trajectories in space. In this regard, representative peri-urban croplands in the black soil region were selected as a case, and soil As, Pb, Hg, and Cd were deemed as the main research objects. Moreover, an affinity propagation algorithm and spatial autocorrelation regression were adopted to measure the contamination patterns and identify the major determinants, in an attempt to reveal how heavy metals are diffused in the peri-urban cultivated area. The results indicated that ① the average concentrations of soil As and Cd were 39.35 mg·kg-1 and 0.183 mg·kg-1, respectively, which exhibited heavier accumulation in the study area. The Nemerow index indicated that there were 52.38% of croplands indicating slight contamination. ② The affinity propagation algorithm identified three potential sources with a similar impact extent for As, which were situated in the typical cultivated area. Both of the two identified potential sources for Pb were situated in close proximity to Fanjiatun Town. The diffusion patterns for Hg and Cd were complex, particularly for the latter, of which the potential sources were scattered in multiple places. ③ The spatial lag model indicated that the distributions of As and Cd were mainly controlled by the intensive agriculture in peri-urban areas, among which As was related to the application of herbicide and Cd was related to the distribution of protected agriculture. Pb was mainly influenced by urbanization and industrialization, whereas Hg was found to be associated with the migration conditions of the soil. However, the regulating function provided by either croplands or their nearby environment did not play an important role in determining the diffusion patterns of heavy metals. The present study enriches the theory and methods for the spatial analysis of cropland heavy metal contamination and is significant for controlling contamination from the source in peri-urban croplands in the black soil region.
摘要：
复杂的城郊环境中农田重金属污染的空间扩散机制为从源头上控制土壤污染以及确保黑土耕地质量提供了至关重要的基础。然而,以前的研究一直在努力寻找污染源或追踪它们在太空中的扩散轨迹。在这方面,选取黑土区具有代表性的城郊农田作为案例，和土壤一样，Pb,Hg,以Cd和Cd为主要研究对象。此外，采用亲和传播算法和空间自相关回归来测量污染模式并确定主要决定因素，试图揭示重金属是如何在城市周边地区扩散的。结果表明:①土壤As和Cd的平均浓度分别为39.35mg·kg-1和0.183mg·kg-1,在研究区表现出较重的积累。内梅罗指数表明，有52.38％的农田表示轻度污染。②亲和传播算法确定了对As具有相似影响程度的三个潜在源，位于典型的耕种区域。两个确定的潜在Pb来源都位于范家屯镇附近。汞和镉的扩散模式复杂，特别是对于后者，其中潜在来源分散在多个地方。③空间滞后模型表明，城市周边地区As和Cd的分布主要受集约化农业控制，其中As与除草剂的施用有关，Cd与保护性农业的分布有关。铅主要受城市化和工业化的影响，而汞被发现与土壤的迁移条件有关。然而,农田或其附近环境提供的调节功能在确定重金属的扩散模式方面没有发挥重要作用。本研究丰富了农田重金属污染空间分析的理论和方法，对黑土区城郊农田污染的源头控制具有重要意义。
