Cr3+污染对稻田土壤的反硝化细菌种群数量及其活性影响的研究

在实验室条件下,对黄松稻田土壤、紫色稻田土壤和红壤稻田土的反硝化细菌(DenitrifyingBacteria,DNB)种群数量及其反硝化活性,以及Cr2(SO4)36H2O处理4周后Cr3+污染对DNB种群数量及其反硝化活性影响进行了研究。结果表明,紫色稻田土壤、黄松稻田土壤和红壤稻田土的DNB种群数量每克干土分别为(59.04～157.59)104cfu、(42.89～108.97)104cfu和(32.14～75.30)104cfu。在每千克干土中加入200mgCr3+时,对稻田土的DNB种群数量及其活性有明显的抑制作用,但稻田土壤还能通过自身的能力,在培养3周后完全恢复稻田土壤的DNB种群数量及其活性。随着Cr3+加入量的增加,Cr3+对DNB的毒性越来越大,稻田土壤通过自身来恢复DNB种群数量及其活性越来越困难,但可通过外界力量(如调节土壤pH)逐渐恢复稻田土壤的生物活性。

Effect of Cr3+ contamination on the population and the denitrification activity of denitrifying bacteria in paddy soils

Effects of heavy metal contamination on the population and the denitrification activity of denitrifying bacteria were investigated in three type of paddy soil:huangsong paddy soil, developed from shallow sea deposit of intermediate lake deposit,red paddy soil,developed from alluvial deposit and purple paddy soil, developed from parent material of neuter purple sandstone and shale, tested with Cr₂(SO₄)₃·6H₂O at different concentrations for 4 weeks. The results obtained showed that the population of denitrifying bacteria of purple paddy soil,huangsong paddy soil and red paddy soil ranged (59.04-157.59)×10⁴、(42.89-108.97)×10⁴ and (32.14-75.30×10⁴ )cells per gram dried soil, respectively. Cr³⁺, adding 200mg/kg dried soil, significantly inhabited the population and the denitrification activity of denitrifying bacteria, but that could gradually recover or close to the levels of the control soil in three weeks by paddy soil itself. It was more difficulty recovers the population and the denitrification activity of denitrifying bacteria by paddy soil itself, when adding concentration of Cr³⁺ was more than 200 mg/kg dried soil. But that could recover by adding some material, which could be increased soil pH. The effectiveness of Cr³⁺ varied on the population and the denitrification activity of denitrifying bacteria in different paddy soils.