| Guided by ecological geochemistry theory,soil investigation is the main part,supplemented by the investigation of atmospheric dry and wet sediments,irrigation water and crop samples,which is a basic investigation work mainly for Quaternary coverage area.The working method mainly refers to the Code for Geological Survey of Land Quality(DB33?T 2224-2019)and the Code for Geochemical Evaluation of Land Quality DZT0295-2016.By measuring the contents of beneficial elements and harmful elements in soil and related soil physical and chemical indexes,a basic geological survey is carried out for the purpose of evaluating the abundance and deficiency of soil nutrients,the law of element migration and transformation and the degree of soil pollution.In this paper,the land in Kecheng district of Quzhou city was taken as the study area,and the city and surrounding suburbs were investigated in detail.Combined with the geological background,soil types and soil-forming parent materials,surface soil,profile soil and root soil samples were collected and tested,and mathematical statistics were carried out by Excel and SPSS software.the geochemical characteristics of shallow soil in the study area were analyzed and studied by Arc GIS platform,and the geochemical grades of soil environment and soil nutrients in the study area were determined.The migration,transformation and accumulation laws of geochemical elements in vertical soil profile and soil-agricultural products were analyzed,thus providing scientific basis for agricultural production and environmental control in this area.Through the research,the following results are obtained:(1)The geological and geomorphic environment of the study area was surveyed on the spot,and the characteristics of regional soil-forming parent material,soil texture and p H value were basically found out.The plain area of soil-forming parent material in Kecheng District is mainly composed of valleys,estuarine alluvium and sediments,and the cultivated layer is mainly composed of loam and clay.The parent material of soil formation in hilly area is mainly acid volcanic weathering,and some are sandstone weathering,and the soil texture is mainly loam.(2)The soil heavy metals in Kecheng study area were evaluated by single factor index method.The pollution area of Cd,Hg,As,Pb,Cr,Cu,Ni and Zn in Kecheng study area was very small,and most of the soil geochemical environment quality was high.Using the "limit condition method" to evaluate the soil environmental quality in the study area of Kecheng,it is determined that the comprehensive evaluation of heavy metal pollution in cultivated land in Kecheng District is clean,and the main heavy metal pollution is cadmium and arsenic pollution caused by human activities.(3)The study on the law of element migration and transformation shows that heavy metal elements Cr and Ni are easy to migrate and not easy to enrich,while heavy metal elements Cu,Cd,Pb and Zn are difficult to migrate and easy to enrich.In the impact of soil environment on agricultural products,the overall pollution degree of crop root soil is not high,and it is mainly clean.(4)Through the study of selenium which is closely related to human health,it is concluded that the content of Se in rice growing areas in Kecheng is low,which is presumed to be related not only to the low content of Se in weathered materials of purple clastic rocks,but also to factors such as supergene geochemical environment.(5)Comprehensive evaluation of soil nutrients in the study area of Kecheng was carried out by using the comprehensive classification table of soil nutrient geochemistry,and the comprehensive grade of soil nutrients in Kecheng District was medium.In the later period,we should reduce the amount of chemical fertilizer and agricultural non-point source pollution. |
PDF Full Text Request