| Guizhou is a typical karst region of southwest China, which is generally considered to be very fragile and poor environmental capacity. Guizhou is a province with rich mineral resources, and large-scale mining brought economic benefit followed by environmental pollution and ecological destruction. Once the karst environment was damaged or contaminated, that threaten karst ecosystem seriously. Therefore, it’s particularly important to study the effects of AMD on the upland soil environment and biology. This paper selected the calcareous soil dry land around typical coal mine as the object of study. Simulating AMD pollution with different addition of AMD to detect the overall characteristic pH, Eh, EC and CEC; nitrogen, phosphorus, potassium, calcium, magnesium and their effectiveness; and the variation of soil metal and microbiological characteristics. The results showed:(1) The calcareous upland soil in karst area had superior cushioning performance against continuous AMD pollution. Soil pH still could remain above 6.65 when the solid-to-liquid ratio was 1:10; with the ratio increasing, Eh, EC increased highly significantly(p<0.01); CEC reduced significantly at low pollution level, but increased at high level.(2) AMD had unconspicuous effect on soil total phosphorus compared with contrast. total nitrogen, total potassium, total calcium, total magnesium reduced significantly; the effective mineral nutrients as available nitrogen, rapidly available potassium, slowly available potassium reduced highly significantly with AMD addition(p<0.01); Low concentration AMD could increase soil available phosphorus, organic matter at some level, but high concentration AMD could promote the release and degradation of available phosphorus and organic matter(p<0.01).(3) AMD with different addition had obvious effect on characteristic pollution parameter. Soil iron, copper, arsenic content were significantly or extremely significantly increased with AMD adding(p<0.05); the tendency of sulfate content under the lower degree of AMD pollution was not obvious, but had highly significant increase under high degree of AMD(p<0.01); soil manganese and zinc increased significantly under low concentration of AMD, but reduced under high concentration especially in the solid-to-liquid ratio of 1:10 was lower than the contrast. On the whole, manganese did not present obvious differences, but zinc presented extremely significant difference(p<0.01); the amount of CO2 release increased extremely significantly(p<0.01).(4) AMD had more obvious effect on the biological indicator of soil. Soil urease activity increased with AMD level increasing under low concentration; but it reduced significantly under high concentration. The microbial biomass reduced with AMD adding, but the tendency rose to extremely significant level under high concentration, overall it presented extremely significant difference(p<0.01).In conclusion, Soil in karst area has certain acid buffer to AMD, but will prompt the Ca2+, Mg2+ in soil of leaching, It would cause lethal effect to which have adapt to the karst ecosystem, calcareous soil formed in the long time of adaptive evolution of calcium plants, the adaptation of karst habitat has very strong dependence, once the plants of the habitat destruction, will cause serious impact to plant growth. Secondly, AMD pollution will cause the soil N、K, especially the effectiveness of leaching, this will affect the plant growth and development condition 、 physiological and biochemical process and crop yield, thus threatens the whole agricultural ecosystem. Once more, when in the higher AMD pollution levels, characteristics of pollutants in the soil of the cumulative sharply, the total soil microbes significantly reduce, soil enzyme activity significantly lower, this will seriously affect the quality of the soil. In addition, AMD pollution will cause a lot of carbon dioxide, so it contribution to the atmospheric greenhouse effect is not allow to ignore. |
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