Studies About Effects Of Irrigation With Mine Wastewater On Wheat Growth And Soil Environmental

In China, most of the mining areas are mainly concentrated in the northern drought areas, whereagricultural water is seriously insufficient but the utilization rate of mine wastewater is low. In order topromote wastewater reusing in agriculture, two experiments were carried out,including long-termirrigation with mine water and coal gangue leaching water in the field,short-term irrigation with minewater and coal gangue leaching water in the pot. The objectives of this work were to investigate the effectsof irrigation with mine wastewater on wheat growth and physical and chemical property of soil, andcontents of heavy metal in soil-wheat system. The main conclusions were as follows:1. Long-term irrigation with mine wastewater had a significant suppression on wheat growth, thatwere reflected in plant height, leaf age and dry weight of single stem, and that were eased by adding dairymanure. The short-term mine wastewater irrigation had no obvious suppression on plant height, leaf ageand relative chlorophyll content of potted wheat, but had a significant suppression on dry weight ofsingle-stem. Generally speaking, compared with normal well water irrigation, the wheat that irrigated withmine wastewater showed a worse situation during the whole growth stage.2. At the beginning of flowering stage, the net photosynthetic rate (Pn) of wheat which irrigated withmine wastewater for short-term was much lower than that irrigated with normal well water; at the end offlowering, compared with the wheat that irrigated by normal well water, there were no significantdifference of Pn between the wheat which irrigated by treated mine water and gangue leaching water, andthe Pn value of the wheat that irrigated with mine wastewater was lowest. The transpiration rate of wheatwhich irrigated with mine wastewater showed a increase at first and then decreased, but there showed agradually increase in the treatment that irrigated with coal gangue leaching water and normal irrigationwater.3. Irrigated with mine wastewater for long-term, urease activity and sucrase activity of soil weresignificantly lower than soil which irrigated with normal well water. Catalase activity of soil irrigated withcoal gangue leaching water was the biggest, and soil irrigated with mine water was the smallest. There wasno significant difference between the treatments which irrigated by normal well water and soil adding dairymanure irrigated with mine wastewater. Soil irrigated with mine wastewater for short-term, had a less urease activity than soil irrigated by normal well water, sucrase activity and catalase activity of soil had nosignificant difference. Short-term irrigation with mine wastewater had been a significantly inhibited on soilreflecting on available N, available P, and CEC, did not had significant influence on soil organic matter andpH.4. Irrigated by mine wastewater for long-term, different organs of wheat had heavy metalaccumulation, but stem and Leaf had the most accumulation. Cr, Zn, Pb obviously accumulated in allorgans of wheat which irrigated by mine wastewater, and were significantly higher than wheat irrigatedwith normal well water. In potted experiment, when irrigated by mine wastewater, the concentration of Crin roots and grains, was significantly higher than wheat irrigated by normal well water. when irrigated withmine wastewater, there had been a high concentration of Cu in spike stalk and glume, and also had a highconcentration of Pb in roots. Other organs showed no significant difference comparing with wheat irrigatedby normal well water.5. While irrigated with mine wastewater and coal gangue leaching water for long-term, theconcentration of Cr and Pb in soil were significantly higher than soil that irrigated with normal well water,but the concentration of Cu and Zn were lower than irrigated with normal well water. Irrigated with minewastewater and coal gangue leaching water for short-term, the concentration of Cu and Pb in soil that werenot significantly different with the treatment irrigated by normal well water, but the concentration of Cr hada little increase. During the whole period of wheat growth, the concentration of Zn in soil had no obviousrule.6. The experiments of irrigation with mine wastewater for Long-term and short-term did not cause soilpollution. Irrigation with mine wastewater for Long-term caused grain seriously pollution by Cr, Cu, Zn, Pb,and all the comprehensive risk index of wheat grains were in the high level. According to the food standard,Pb and Zn contents in wheat grain exceeded the standard while irrigated with mine wastewater forshort-term, the single pollution index of Cr of wheat grain reached moderate to high pollution level. All thecomprehensive risk indexes of wheat grain were in the high level.