| Soil is the premise for human survival and long-term development.With the rapid development of industry and the enhancement of human activities,soil fertility declines and heavy metal pollution becomes more and more prominent.Soil quality has become a hot issue of high concern to the country and the public.The study area is located in the middle Chengdu plain,mainly farm land,is an important grain,vegetables,fruit producing area in China,large population,grasp the content of topsoil elements in the area and distribution characteristics,the degree of nutrient abundant deficiency,situation and sources of heavy metal pollution,soil quality to guide agricultural production activity,the ecological risk assessment,reasonable planning and utilization of land resources has important practical significance.In this paper,financial supported by China geological survey geological survey projects,find out in the area to basic geological survey and soil on the basis of the content of elements by geological statistics analysis method,the positive definite matrix factorization method model(PMF),minimum data set(MDS)on the source of topsoil in the study area element geochemical characteristics,the source of heavy metals and soil quality were studied and evaluated,the results showed that:(1)The average p H value of the topsoil in the study area was 6.44,and the average content of eight major heavy metals were found.Compared with Chengdu Economic Zone,the toxic As and Hg in the topsoil were relatively worsen,while other heavy metals were close to the local background value.Nevertheless,Cd,Cu,Hg and Pb are relatively deteriorated by compare with China topsoil,and As,Cr,Ni and Zn are close to the value.(2)The soil were enriched with total-K(44.43% area)and total-P(38.34% area),by compare,the total-nitrogen and organic matter are relatively deficient.The comprehensive evaluation soil nutrient was reached 3-degree(52.5% area),appropriately 23.26% are rich,24.24% are infertility.(3)The soil environment is in the clean and clean state as a whole,except for a slight pollution of Cd and Cu.The 1-degree and 2-degree soil in the study area are count to 92.85% and 7.09% respectively for other toxic metals.(4)The soil quality is good on the whole.the geochemical grade of the topsoil quality in the study area can be divided into 5 grades,from 1-degree to 4-degree,the occupied land are 9.57%,55.29% 32.80%,2.34%,0% respectively.The area with good or good soil quality accounts for 64.86%.(5)the provenance of As,Cr,Cu,Hg,Ni,Pb and Zn in the soil were studied from positive definite matrix(PMF).The impact factors order is agricultural and natural sources(33.52%)> industrial sources(19.62%)> natural sources(18.54%)> traffic sources(13.31%)> coal sources(15.01%).(6)The MDS indexes for the comprehensive evaluation of soil nutrients in the study area were: organic matter,total phosphorus,Zn and Co.The results of the comprehensive evaluation of soil nutrients based on MDS showed that the area with a score higher than 0.6(40.49% area),the quality of soil nutrients was good.Moreover,the comprehensive evaluation results of soil nutrients in the study area based on MDS index can well represent the comprehensive evaluation results of soil nutrients in total date set(TDS). |
PDF Full Text Request