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Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] In order to understand the content characteristics and ecological risk of heavy metals in agricultural soils in small-scale areas of karst regions, the present paper provides reference for the utilization of land function and the protection of cultivated soil environment. [Method] A total of 27 sites were laid on soil on agricultural land in the southwestern of Guizhou Province, samples of surface soil ( 0 - 20) cm were collected, and 8 heavy metal elements such as pH and Cd, Hg, As, Pb, Cr, Cu, Zn and Ni were analyzed and determined. The 'Soil Environmental Quality-Soil Pollution Risk Control Standard for Agricultural Land' (GB15618 - 2018) was used as the evaluation criteria to analyze its distribution characteristics, ecological risks and sources. [Result] The results showed that the soil pH in the study area was 5. 46 to 8. 07, and the average contents of heavy metals Zn, Cr, Pb, Ni, As, Cu, Cd and Hg were 154. 24, 153. 71, 64. 25, 61. 76, 50. 38, 49. 86, 0. 41 and 64. 25 mg/kg, respectively. The soil pollution index of agricultural land in the study area was 1. 68 and 1. 38, respectively. The hazard index (IR) value of 8 kinds of heavy metals was 69. 00, which was less than the limit of ecological hazard (IR = 150) . Cd and Pb, Hg and As, Cu, Zn, Ni, As and Cu, Zn, Ni, Cr, Cr and Cu, Zn, Ni, Zn and Ni have homology respectively, and there is compound pollution. The results of the main component analysis show that As, Hg, Cr, Cu, Zn, Ni have a higher load in the first main component, the variance contribution rate is 57. 565%, the content is mainly caused by the long-term application of heavy metal fertilizer; Cd and Pb have higher load in the second principal component, and their variance contribution rate is 80. 277%. The higher content is mainly due to the higher content in the parent material. [Conclusion] The soil pH of agricultural land in the study area is 5. 46 - 8. 07 which has been polluted by As and Cd to different degrees. Cr and Ni pollution is still clean range; Hg, Pb, Cu and Zn are in the clean range. The pollution level is slight ecological hazard [ABSTRACT FROM AUTHOR]

China as a biggest producer of electrolytic manganese is in the imperative to ameliorate the soil pollution which caused by electrolytic manganese waste residue. In this study, a survey was undertaken at a electrolytic manganese residue storage in Caixi Village of the Yuping Dong-minority Autonomous County under the jurisdiction of Tongren City of Guizhou Province, where the largest reserve of manganese ore resources in China is situated. To understand the characteristics of soil pollution, the speciation distribution of heavy metals (incl. Mn, Zn, Pb, Ni, Cr and Cd), and ecological risk of heavy metal contamination of the soil around the electrolytic manganese residue storage were analyzed by wet digestion and BCR sequential extraction. Mn, Pb and Cd, inter alia, had caused the severest impacts on the environmental quality of soil: Mn concentration was in the range of 356~14 915 mg/kg, with an average of 3 828 mg/kg, being 4.8 times higher than the background value of the soil in Guizhou; and the average concentrations of Pb and Cd were 3.1 and 40.2 times, respectively, higher than the "risk screening values of the National Standard for Farmland Soil". As to the heavy metal speciation, six species of heavy- metal were mainly composed of migratory dissolved weak acid, and the content of dissolved fraction of weak acid of Mn and Cd in soil increased as the distance got closer towards the residue storage dam (P<0.05). According to the analytic result by using the common Kriging spatial interpolation, there existed a kind of moderate spatial correlation among the content of Mn, Cd, Zn, Pb and Ni; in addition, the content of Mn and Cd, among others, were randomly affected by the pollution of human activity considerably; and the spatial distribution of concentrations of Mn and Cd in general showed the higher in the east and lower in the west parts of the area being investigated, and the high values of Mn and Cd concentrations were found mostly near the dam of the waste residue storage; and the results of principal component analysis (PCA) indicated that Mn, Cd and Pb were mainly resulted from the pollution of electrolytic manganese residue, while the contamination sources of Ni and Zn could be traced to the nearby agricultural activities and industrial production. Furthermore, Cr was mainly affected by the geological background factors, the highest potential ecological risk level belonged to the soils in proximity to the waste residue storage, and particularly, the contribution ratio of Cd was the highest (91%). [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to provide the scientific basis for rational land-use planning, soil resources conservation and pollution-free agricultural development in Luodian County, Guizhou. [Method] The effects of five typical land-use patterns (forestland, natural grassland, artificial grassland, cropland and abandoned farmland) on content and environment contamination of Cd, Cr, Pb, Ni, Hg and As in topsoil were evaluated by Nemerow comprehensive index, single-factor contamination index and Hakanson potential ecological hazard methods. [Result] The content of 6 heavy metals in topsoil was Cr > Pb > Ni > As > Cd > Hg and lower than the contamination background value of heavy metals in Guizhou overall. The topsoil Cd content was the highest in abandoned farmland and lowest in forestland. The topsoil Cr content was the highest in abandoned farmland and lowest in natural grassland. The topsoil Pb and Hg content was the highest in cropland and lowest in forestland. The topsoil Ni content was the highest in artificial grassland and lowest in natural grassland. The topsoil As content was the highest in natural grassland and lowest in cropland. The topsoil Cd, C.r, Pb and Hg content was high relatively and greatly influenced by human activity. Topsoil Cr had the same source as Ni, Hg and As. The topsoil As content was closely related to soil pH. The topsoil Cd and Cr content was closely related to soil cation exchange capacity (CEC) . The topsoil Pb, Hg and As content was closely related to soil organic matter (SOM). [Conclusion] Six heavy metals in topsoil do not cause soil contamination. The single-factor contamination index and potential ecological hazard index both are at the clean level. The pollution-free agriculture can be vigorously developed according to local soil nutrient, soil fertility and land-use pattern in Luodian County, Guizhou. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)