Geo-accumulation Index Method to Optimize the Evaluation Method of Polymetallic Environment Quality: Taking Developed Agricultural Areas as an Example

Abstract

An accurate and reasonable soil pollution assessment method is the premise of regional soil pollution assessment. Triangular fuzzy numbers were introduced into the geo-accumulation index method, combined with α-cut technology and the Latin hypercube sampling (LHS) stochastic simulation method, to evaluate the accumulation of heavy metals in five different soil types (moisture soil, aeolian sandy soil, cinnamon soil, loessal soil, and alluvial soil), with large differences in heavy metal (Cd, Hg, As, Pb, and Cr) content in the study area. This method can avoid the inaccuracy of the evaluation results caused by the traditional geological accumulation index method in the selection of background values and the great difference between local and whole heavy metal contents in the study area and can comprehensively and truly represent the regional soil heavy metal pollution status, thus providing a theoretical basis for scientific decision-making. The results showed that the improvement in the method will not affect the evaluation results when the heavy metal content difference is small, that is, when the evaluation results of the geological accumulation index at all points are within a certain interval level or when the evaluation results of the geological accumulation index at all points are less than 0. The traditional and geological cumulative index method based on the evaluation with triangular fuzzy numbers provides results for a certain level, which is determined by the heavy metal content in the study area average; conversely, differences in the heavy metal content of soil sampling points throughout the study area can result in a decrease or increase in the recorded heavy metal contents in larger areas, making the evaluation result inaccurate. Combined with the LHS sampling method, the possibility of changing the evaluation results into various pollution levels can greatly improve the limitations of traditional evaluation methods and make the evaluation results more reasonable and accurate. Combined with the geographic information system (GIS) method, the regional heavy metal pollution accumulation concentration can also be visualized.