Study On Geochemical Evaluation Of Land Quality Of The Typical Villages And Towns In Jiangshan City,Zhejiang Province

Based on the data of 1:50,000 land quality geochemical surveys in the four typical townships of Hecun Town,Qinghu Town,Xitou Town and Xintangbian Town in Jiangshan City,Zhejiang Province,this paper is based on elemental geochemistry in soil and rice in the study area.The characteristics were analyzed.According to the characteristics of the fragmentation of the ground and the changeable geological background in the southern hill basin area to which the study area belonged,the unsampling method was used to perform sampling experiments on the actual sample sites in the study area.The error analysis of measured values,predicted evaluation grades and measured evaluation grades determines the optimal interpolation and assignment methods suitable for the study area;according to the optimal interpolation and assignment methods suitable for the study area,refer to the relevant regulatory requirements.The overall situation of soil environment,soil nutrients and soil quality in the study area was evaluated and the following results were obtained:(1)Through analysis of elemental geochemical characteristics of soil and rice,it was found that the content of nutrient elements P,manganese,molybdenum,selenium,and iodine in the soil in the study area was higher than the average value of surface soil in Zhejiang Province;The contents of mercury,cadmium,lead,and zinc were lower than those of the topsoil in Zhejiang province.Affected by the Cretaceous basalt strata,the contents of nickel,chromium,and copper were higher than the average of the surface soil in the province.(2)The comparison of the error analysis of prediction data and measured data,the comparison of the prediction rating and the actual evaluation rating indicates that the accuracy of the inverse distance weight interpolation method is higher than that of the Kriging interpolation method;the precision of the point-to-point assignment method is higher than The accuracy of grid evaluation method,thus establishing the inverse distance weight interpolation method and point-to-point assignment method as the interpolation and assignment of the unknown point in the study area,and using this method to carry out geochemical evaluation of the land quality in the study area.(3)According to the elemental geochemical content and distribution characteristics of the soil in the study area,using inverse distance weight interpolation method and point assignment method,and referring to the land quality evaluation specification(DZ/T 0295-2016),to Hecun Town and Qinghu Lake The geochemical comprehensive evaluation of the soil quality in the four typical townships of Zhen,Jiaotou and Xintangbian Towns showed that the soil in the area was generally cleaner,and the proportion of soil nutrient comprehensive levels in the area was only 22% in the fourth and fifth grades.In the integrated grade of environmental classification,the ratio of primary and secondary accounts for 85%.In terms of the comprehensive classification of soil quality,40% of high quality and good soil are mainly distributed in Qinghu Town and Xintangbian Town,and 18% of them are poor.The inferiority is mainly distributed in the northwest of Hecun Town.(4)According to the evaluation of the content and distribution of selenium in the soil of the study area,the proportion of selenium-enriched soil in the study area has reached 30%,and according to the relevant regulations,three selenium-enriched farmland areas have been established,covering an area of 6.9 million mu.It provides a geochemical basis for the development of selenium-enriched rice in this area in the later period.