Research On The Optimal Allocation Of Agricultural Land With Heavy Metal Over Standard To Achieve Safe Utilization In The Township Scale

At present,soil heavy metal pollution invisively affects not only the quantity and quality of agricultural land,but also the safety of agricultural products,and it may be a threat to people’s health.Therefore,it is necessary to provide a good reference for the safe utilization and protection for the agricultural land in the study area by carrying out the study on the optimal allocation for agricultural land with heavy metal over standard to achieve safe utilization.Firstly,this paper predicts the spatial distribution of future land use in the study area based on the CLUE-S model.In addition,based on the integrated evaluation criteria of the safe utilization of agricultural land with heavy metals over standard in the study area,the single factor index method is adopted to evaluate the situation of heavy metals over standard in the study area,adjusting the land type for the agricultural land in middle and severe pollution levels to the safe utilization direction.At last,according to the results of safety utilization evaluation and the prediction results of the model,the spatial distribution of future land use of the agricultural land in the middle and severe pollution level was identified,and the comparison was made with the conversion direction of the land type based on the safe utilization evaluation criteria to determine the rationality of the use direction.The main study results are:(1)Through the analysis of land use change characteristics in the study area,the rapid development of local economy and township enterprises developed,so that the area of construction land was expanded greatly,the area of paddy field and dry land and irrigated land was obviously increased.Due to land development and finishing or village renovation and other reasons,the land were organized into a farming state,so that the area of other land was significantly reduced,and the area of garden plot and forest land is obviously decreased.(2)Based on the results of safety utilization evaluation,the area of agricultural land in the middle and severe pollution level accounts for 0.4% of the total area,mainly distributing in the vicinity of the built area.According to the safe utilization evaluation criteria to adjust the agricultural land in moderate and severe pollution levels to be the safe utilization direction.The results showed that there was no significant difference in the limit of heavy metal concentration between paddy field,dry land and irrigated land at the same pH value,so there was no mutual transformation,and the conversion direction of the land type are garden plot and forest land.After the conversion of land type,the relative degree of heavy metals over standard of agricultural land are reduced,it initially achieved the safe use in standard sense.(3)According to the results of safety utilization evaluation and the prediction results of the model,the change of agricultural land with heavy metal over standard in the study area from 2013 to 2021 was analyzed.It was found that most of the paddy fields,dry land and irrigated land maintain the original use mode,and others were adjusted to construction land and other land.Compared with the conversion direction of the land type based on the safe utilization evaluation criteria,analyzing the rationality of the use direction from the perspective of the safe utilization and the actual use respectively,and putting forward control recommendations for reference.In this paper,the optimal allocation for agricultural land with heavy metal over standard to achieve safe utilization can provide a perspective and a program basis for the safe utilization of agricultural land in heavy metal pollution area.