碱式硫酸铝溶液吸收二氧化硫

为了探讨碱式硫酸铝对二氧化硫的吸收效果,对所需试剂硫酸铝和碳酸钙的适宜比例（碱度）,以及碱式硫酸铝能稳定存在的铝量范围等进行了研究,测定了不同铝量和碱度的碱式硫酸铝对二氧化硫的吸收量以及pH值,并分析每种吸收液的饱和吸收量,最后将其与乙二胺/磷酸溶液的吸收情况进行对比。结果表明,碱度为40%时,铝量要保持在70 g/L以下才能在加热时不产生沉淀,吸收过程pH由4.5左右一直下降到2.0左右保持稳定,饱和吸收时间控制在140~160 min为宜,较为理想的方案是铝量32 g/L,碱度35%。     

红壤中La对油菜的剂量效应和临界浓度

通过盆栽试验,研究了红壤中不同浓度La对油菜的生长、产量、叶绿素含量和过氧化物酶活性的影响.结果表明:低浓度La可促进油菜生长并增加产量,但达不到显著水平;300mg·kg^-1以上的高浓度La则显著抑制油菜生长和降低产量.La浓度为600mg·kg^-1时油菜死亡,油菜产量降低一半时的EC50=300mg·kg^-1.La浓度为15 mg·kg^-1时油菜叶片叶绿素和叶绿素a/b分别减少,POD活性随La的浓度的增加和施加时间的延长而逐渐增加.     

Effects of plant species coexistence on soil enzyme activities and soil microbial community structure under Cd and Pb combined pollution

The relationship between plant species coexistence and soil microbial communities under heavy metal pollution has attracted much attention in ecology. However, whether plant species coexistence could o set the impacts of heavy metal combined pollution on soil microbial community structure and soil enzymes activities is not well studied. The modified ecological dose model and PCR-RAPD method were used to assess the e ects of two plant species coexistence on soil microbial community and enzymes activities subjected to Cd and Pb combined stress. The results indicated that monoculture and mixed culture would increased microbe populations under Cd and Pb combined stress, and the order of sensitivity of microbial community responding to heavy metal stress was: actinomycetes > bacteria > fungi. The respirations were significantly higher in planted soil than that in unplanted soil. The plant species coexistence could enhance soil enzyme activities under Cd and Pb combined. Furthermore, planted soil would be helpful to enhance soil genetic polymorphisms, but Cd and Pb pollution would cause a decrease on soil genetic polymorphisms. Mixed culture would increase the ecological dose 50% (ED50) values, and the ED50 values for soil enzyme activities decreased with increasing culture time. The dehydrogenase was most sensitive to metal addition and easily loses activity under low dose of heavy metal. However, it was di cult to fully inhibit the phoshpatase activity, and urease responded similarly with phosphatase.