Disscussion On The Mechanism Of Detoxification Of Sulfur And Ferric Oxide On Copper And Chromium Contamineted

This study used pot culture and water culture experiment to discuss the effects of sulfuron the content of MDA in leaf SPAD and biomass with wheat, corn and rice respectivelyunder copper stress by controlling the copper and sulfur levels in soil or hydroponics nutrientsolution; Comparing the MDA content, SPAD value, biomass, root hydraulic conductivity androot to express the changes of iron content and other indexes by adding ferric oxide to the soilor preparing the artificial root iron plaque. Through adding Cr slag into soil to simulate thechromium contaminated soil samples to explore the method of cleaning anaerobic pollutantsand the removal efficiency of chromium(VI) in the artificial wetland treatment system, andthen, doing the comparison of the effects on wheat growth in different treatment of soil.The main results are:1. Influences of sulfur nutrition on the growth of corn under copper stress(1) On the stages of seedling and jointing, the contamination of copper pollution which issimulated in the soil (400mg/kg) has significant inhibiting treatment on plant biomass; Whereas, it increased significantly after the distribution of sulfur fertilizer than in copper pollutiontreatment. This fact indicated that sulfur nutrition can promote the reduction of the effect onthe plant biomass of corn, which caused by the copper.(2) According to the different SPAD in different treatment, we found that when thesulfur was applied to the soil as a necessary nutrients of plants, it can increase the SPAD ofmaize plant obviously. To apply400mg/kg soil concentrations of copper to the soil, the SPADvalue in corn leaf decreased significantly with the comparison of blank experiment. Whileapplying50mg/kg soil concentrations of sulfur, the negative stress was mitigated. It will bestronger and stronger with the growth of corn.(3) In the beginning of testing, the400mg/kg copper made the enable MDA contentincrease and showing the copper stress can strengthen peroxidation degree of membrane inthe corn leaf; When the soil was applied50mg/kg sulfur, the leaves had decreased in thecontent of MDA.This phenomenon indicated that the sulfur played a certain role inalleviating the copper stress. 2. Influences of sulfur nutrition on the activity of ATPS in maize leafIt had a negative effect on ATPS activity to increase the sulfur in soil. However, it couldstrengthen the activity of ATPS on the condition of copper stress. It showed that sulfurnutrition had a positive regulation on ATPS activity under heavy metal stress. In different soiltypes, there were certain differences of the role of sulfur nutrition. The affection of sulfurnutrition in Northern Shaanxi Sandy Soil was stronger than in Guanzhong clayey soil.3. The effects of iron oxide on crops to resist the copper pollution(1) To add iron oxide to the soil which was simulated the copper contamination, theSPAD values of rice plants increased significantly. This result showed that iron oxide had apositive effect on maintaining the chlorophyll of plants, though more iron oxide would be notconducive to the biomass of rice seedling, causing MDA content increased slightly.(2) Through the hydroponic experiment of artificial root iron plaque, we found that,under the gradient increased copper concentration conditions, although copper stress can leadto the decreasing of SPAD and increasing of MDA content, both of them had not significantlychanges for96hours of continuous stress, and the copper concentration increasing from1to15mg/L. This result showed that artificial root iron plaque on rice root could increase thetolerance of copper pollution and contribute to maintain the high chlorophyll levels, as well asdeclining the content of MDA.(3) By determination the root hydraulic conductance, we found that the artificial rootiron plaque could promote the increasing of the hydraulic conductivity of rice root systemunder Cu2+stress, even could be similar with the contrast treatment. In contrary, roothydraulic conductance would decrease without the root iron plaque. It explained that theartificial root iron plaque was able to reduce the Cu2+stress through changing the roothydraulic conductivity.4. Simulated artificial wetland treatment on the role of chromium pollution elimination(1) The content of Cr (VI) in the soil which was under the anaerobic treatment for10and20days by flooding method decreased from200mg/kg to below0.5mg/kg. And the rateof purification could reach above99.7%. Adding ferric hydroxide to the soil could have apositive effect on Cr(VI) reduction. What is more, the rate of Cr(VI) purification wassignificantly higher than the treatment without ferric hydroxide.(2) Doing the biological experiment with treated soil, the wheat biomass wassignificantly higher than that without treatment of chromium-containing soil and so did thetreatment which added the ferric hydroxide. It showed that the flooding treatment played aimportant role in reducing the chromium pollution in soil.