Source Apportionment And Environment Capacity Of Pollutants In Soil Of Hanjiang River Delta, Guangdong Province

Ever since the twentieth century, along with the rapid growth of population, the flourishing development of difference industries, the extensive utilization of manufactured products in daily life and the impressive increase of energy demand of China, a considerable quantity of contaminants including heavy metals and organic pollutants emits into various environmental medium. Rising pollutants emission in urbanization and industrialization processes overwhelmed the self-cleaning ability of soil, water and atmosphere system. These problems have been attracting considerable attention over the past few decades.The distribution of pollutants in soil are quite complex. Firstly, there generally exists a multiple source which produces different quantity of contaminants with similar or significant characteristics. Secondly, the major contaminant sources have usually been surrounded by other minor sources causing it hard to separate between the mixtrure sources. The process is further complicated by the fact that few sources emit persistent while some are discontinuous.The study area is located in Chaoshan plain of southeast Guangdong Province including Rongjiang, Lianjiang and Longjiang River. A large amount of small industrial and mining enterprises and family workshops exist in the study area. The environmental quality of the study area continues to deteriorate since such production models. In support of the Guangdong provincial government and department of finance of Guangdong province, the environmental quality of the core economic region of Hanjiang Delta have been studied thourgh abundant of representative soil, water and plant samples. The major elements and pollutants of these samples have been analyzed to clarify the spatial distribution, source, ecological efficiency, potential risk of them.The results showed that, the soil which achieved the Grade II China Environmental Quality Standard for Soils distributed widely in the area. On the basis of the pollution load index (PLI) and geo-accumulation index (Igeo), it appears that pollution level of Pb, Ni, Cd, Hg, Cr and As was 2,3,3,3,3 and 5, respectively. Ecological risk of Cd is quite high as bioactive species of it even reach 56.21%. On the basis of the delayed geochemical hazards model, there are 31.95% of As,21.74% of Pb and 4.62% of Ni in the soil of the study area have exceeded the threshold of breaking point.In the present study, a large data matrix has been obtained from the project named agricultural geology and ecological geochemistry surveys of Hanjiang Delta. The data base was subjected to a receptor model with the objective to extract some information about the environment characteristics of the sampling places, identification of soil, water and plant quality parameters responsible for spatial variations in environmental medium, the potential factors interpretation the constitution of the data matrix, the effect of the major sources on the environmental quality.8 principal component have been extracted by receptor model and explained about 15.2%,11.7%,9.6%,8.7%, 5.7%,4.5%,3.7% and 3.7% of the original total variance, respectively. The regional environment was controlled by geological background and influenced by anthropogenic activities according to the results of the source apportionment which have been multiple verified by regional geological background, characteristics of environmental geochemistry and prospecting area.We have evaluated the geochemical environmental carrying capacity based on the extracted sources and compared the evaluation result with the conclusion through traditional assessment method. We have substituted the expert grade method in the traditional method with source contributions that calculated by the present study. Subjective factors produced by the traditional assessment method have been reduced effectively in this study.To solve the collinearity that can produce the mixtrue sources mentioned in above, concentrations and distribution of the twenty-one mineral elements and sixteen polycyclic aromatic hydrocarbons (PAHs) collected in Guiyu were evaluated. Principal component analysis (PCA) in combination with multiple linear regression analysis (MLRA) was applied in source apportionment of major pollutants.PCA/MLRA applied to the data matrix of PAH in the soil extracted three major factors explaining 85.7% of the total variability identified as traffic emission (37.5%), coal combustion (35.1%) and an unidentified source (13.1%). By using metallic or metalloid element concentrations as variables, five principal components (PCs) were identified and accounted for 70.4% of the information included in the initial data matrix, which can be denoted as e-waste dismantling related contamination (22.6%), two different geological origins (16.1% and 12.5%), anthropogenic influenced source (7.8%) and marine aerosols (11.4%).The combined mineral elements and PAHs dataset not only identified different e-waste recycling technologies, pollution patterns of various villages and transportation paths of the study region, but also reasonably explained the remaining source that can not be interpreted through mineral elements or PAHs dataset separately. It is concluded that, combination of the organic and inorganic chemicals can effectively assist the source identification process by narrowing down an ambiguous source in the present study.