| Purpose: Regarding the soil of Zhalong Wetland in Hei Longjiang Province as the object, the relationship between the ground physical and chemical properties and heavy metal concentrations is studied, as well as the biological characters, parts of Physiological and biochemical indexes of a strain. That is to say, using the resistant strains separated from festuca and the experiment as a tool to repair the heavy metal pollution, the goal is to study the effect of plants repairing heavy metal alone and coalition effect added microbes.Method: First, 10 samples of soil are chosen, which come from seriously polluted areas in Zhalong Wetland. Second, the metal contents of copper, iron, manganese, zinc, cobalt, lead, cadmiun, chromium, together with their physical and chemical properties and conductivities are determined, then calculating these statistics and analyzing their relativity. Third, 8 heavy metal major opponents are refined through major opponents and path analysis, which combined the calculation ago, the study gets the situation about the direct and indirect influence on the soil. Then, a strain anti lead and cadmium is tested, and recognized with 16 SrDNA sequence analysis, researching the influence of Pb2+, Cd2+, Pb2+/Cd2+, the temperature, pH value, salt and antibiotics to the growth of strain. Next, festucas are planted into sample soil to which respectively is added Pb(NO3)2 only polluted by Pb, CdSO4 only polluted by Cd, Pb(NO3)2 and CdSO4 with united pollution of Pb and Cd, then which is mixed and waited for 3 months, comparing to no any heavy metal. Festucas biomass and plant-to-heavy metal accumulation amounts are measured.Result: Through related analysis, the complicated heavy metal brings about the influence of chemical characteristics and electrical conductivity, including the noticed negative correlation between Fe, Co, C and K+, Fe, Co and Na+, as well as the noticed positive correlation between Pb and pH, Fe and EC, Co and EC, Cu and Ca2+, Co and Ca2+, Cr and Ca2+. The NO.1 major component analysis shows the function of Cu, Fe, Mn, Cr, Co and Zn, whose increasing content will result in rising the index of EC and Ca2+, while declining that of Na+ and K+, but almost no effect to p H value. The NO.2 component shows the effection of Pb and Cd, which mainly affect the change of pH value inside of the soil. Depending on the path analysis, the effect of lead and cadmium to power of hydrogen is the most noticable, however, other metal elments, duing to the problem of cancelling out of their direct and indirect functions, don’t make the enormous effect to pH value, especially the effect of Fe and Cr to EC. The existing of most heavy metals will decrease the content of K+ and Na+ in the soil, but no much influence on Mg2+. The chosen resistant strains are turned to be Enterobacter ludwigii, which has strong ability of anti lead and cadmium and can be bred in low phosphorus and nitrogen-contained medium with Pb2+(300 mg/L) and Cd2+(200 mg/L). The removal rate and adsorptional rate of this strain to Pb2+ respectively reach 40.54% and 25.14%, its proper temperature for growing is 25℃ and the power of hydrogen is 7.0. By the way, the strain is hypersensitive to Imipenem and its growth will be restrained by the increasing mixed concentration. Through the biomass change of festucas after enriching heavy metals, the result can be got that festuca’s biomass both on and under the ground decrease with lead and cadmium rising concentration in the soil. When the concentration of lead and cadmium in the ground is below 150 and 125 mg/kg, which means depending on the rising concentration of Pb and Cd, the heavy metal in enriched festuca will increase. Turnover, if the concentration of Pb and Cd is above 150 and 125 mg/kg, the trend of this increasing will be unnoticed slow.Conclusion: The content of heavy metal in the Zhalong Wetland directly effect the soil property, which means that the increasing quality of heavy metal in the ground will bring the changes of ecotope, even determing the deterioration. From the experiment of breeding and choosing Pb-Cd resistant strains that can tolerate high concentration and have effective removal rate, the JB13 strain can more strengthen festuca’s enrichment to the heavy metal. In addition, compared to the restrain function of Pb to festuca, Cd works better, but the compound which mixed by both is the best. The effect of festuca enrichment also shows heavy metal in the part of under ground is higher than that on the ground. Besides, festuca can repair the soil better polluted by one heavy metal than that by mixed metals. Their virulence is Pb-Cd>Pb>Cd. |
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