| The geochemical evaluation on the land resources quality is based on geochemical indicators,such as nutrient beneficial elements,heavy metal elements and compounds,organic pollutants,and soil physical and chemical properties,that affect the land resources quality,and their influenced degree on the basic functions of the land resources,mainly based on soil geochemical surveys.Taking into account the geochemical survey of the atmosphere,irrigation water and crops,assessing the geochemical grade of land quality,in order to quantify the land quality,realize the comprehensive evaluation project of dynamic management and utilization of result data.The geochemical evaluation indicators of land quality are mainly based on soil nutrient indicators and soil environmental indicators that affect land quality,supplemented by air quality,water quality and agricultural product safety,and comprehensively consider various factors related to land use to realize the geochemistry evaluation of land quality,the results can be widely used in the fields of land management,regional environmental protection and modern agricultural development,and are the basis for the rational use of land,the improvement of food production and the quality of agricultural products,besides the improvement of the ecological environment.For this reason,the Ailao Mountain area in Xinping County of the southern Yunnan is selected as the research area.Soil,atmosphere,irrigation water,and crops are the main survey media,guided by the theory of ecological geochemistry,methods of geochemical survey and evaluation are used.detailed investigation and evaluation was Carried out,distribution,control factors and causes of elements in soil were obtained.This study provides suggestions on the planning and utilization of regional land resources,agricultural economic zone planning,and planting structure adjustment.This research mainly achieved the following conclusions:(1)The soil nutrient status of the study area was generally good.More than half of the area shows a third-class level(53.93%);area shows second-class(richer)and fourth-class(less)accounts for 25.39% and 15.05%,respectively;the first-class(rich)and fifth-class(lack)accounts for 4.25% and 1.39%,respectively.which display a small amount of levels.(2)The environmental quality of soil in this area was excellent and good.The comprehensive grades were mainly first-class and second-class,with an area of 78.74% and13.36%,and there was a very small amount of fourth-class and fifth-class contaminated soil,which account for 5.32%.The heavily polluted areas were mainly concentrated in Pingzhang-Mengnong-Jianxing and Yaojie-Yutang-Liming area.The former polluted area was mainly related to the ultrabasic rocks,soil in this region shows a pollution of heavy metal Cr and Ni,the other polluted area was mainly related to the iron-copper ore-bearing rocks of the Dahongshan Group,the pollution element was mainly Cu.(3)The atmospheric environment and irrigation water environment in the area were both first-class,and the safety and quality of crops were generally good.Among them,ratio of crop safety accounted for 88.78%,and risky crops from heavy metals(accounting for 11.22%)were mainly rice.(4)The comprehensive grades of land quality in this area were mainly first? third-class,with an area of 19.06%,45.25% and 26.46%,respectively.There were a small amount of fourth and fifth-class,with an area of 3.91% and 5.32% respectively,which mainly distributed near the Dahongshan Group in Gasa-Mosha region and ultrabasic rocks in Pingzhang-Jianxing region,which were basically consistent with the soil environment distribution.(5)In view of the existing problems on land quality in the area,comprehensive evaluation of selenium resources and heavy metal distribution w as carried out,the causes of selenium-rich and source of heavy metals in soil were identified.The results show that,The coefficients of variation of all elements show a wide range except for Zn in a medium variation,the pollution sources are mainly affected by geological background,mining activities,human life and other factors.Se in soil mainly comes from the secondary enrichment of soil-forming parent material,and the influence of irrigation water and atmospheric dry-wet deposition is relatively small.the soil in the Permian and Carboniferous strata shows a high enrichment of Se than soil in other area.Potential ecological risks assessment and the development and utilization suggestions of the soil in the area were evaluated,which enhanced the practical value of the survey results.(6)The research results provided a direct basis for land resource utilization planning,agricultural economic zoning,and planting structure adjustments in the Ailaoshan area of Xinping County that could provide reference for land quality investigation,evaluation,besides development and utilization in similar areas. |
PDF Full Text Request