乐果与Cd2＋复合污染对土壤微生物生态效应研究

Eco-toxicological Effect of Cadium and Dimethoate Combined and Simplex Pollution on Soil Microbe

土壤微生物数量及土壤酶活性是描述土壤的重要生物学指标。在实验室控制条件下,研究了农药乐果、Cd2+单一污染及乐果与Cd2+复合污染对土壤3大类群微生物数量和主要土壤酶活性的影响。结果表明,Cd2+和乐果复合处理对土壤中微生物生长存在着明显的拮抗作用,复合抑制效应顺序为放线菌>真菌>细菌;而对土壤酶活性均有明显的协同作用,复合抑制效应顺序为蛋白酶>蔗糖酶>脲酶。单一污染时,100mg·kg-1乐果的处理可不同程度地抑制这些生物学指标,其中对土壤微生物数量的抑制效应顺序为真菌>放线菌>细菌,对土壤酶活性的抑制效应顺序与乐果和Cd2+复合污染顺序一致;50mg·kg-1浓度的乐果对这些指标几乎无影响。

Dimethoate is an insecticide widely used on fruit trees, leaf vegetables, cotton and other horticultural crops to control sucking in- sets. Owing to the widely pollution of Cd2＋ in farmland, there is a widespread belief that the phenomenon of Cd2＋ and dimethoate Combined Pollution is existence commonly in farmland ecosystem which using dimethoate frequently. This paper aims at discussing eco-toxicological effect of Cd2＋ and dimethoate combined pollution on soil microbe. The polluted soil enzyme activities （invertase, urease, proteinase ）determined by colorimetry method and microbial population determined by the pour plate method were studied in simulative experiment condi- tion. The results showed that there existed synergistic inhibiting effect on the soil enzyme activities; The order of inhibiting rate of soil enzyme activities under 100 mg·kg-1 dimethoate simplex pollution and the compound pollution of cadmium and dimethoate were proved to be：pro- teinase〉invertase〉urease; Antagonistic inhibiting effect on the population of soil microbial under the compound pollution of cadmium and dimethoate were found in this experiment results. The order of inhibiting rate of soil microbial population under the compound pollution were proved to be：actinomyces〉fungi〉bacteria; Under the 100 mg · kg-1 dimethoate simplex pollution the inhibiting effect on soil enzyme activities were proved to have and the order of inhibiting rate of soil microbial population was：fungi〉actinomyces 〉bacteria; The results also showed that there are no inhibiting effect on the soil enzyme activities and soil microbial under 50 mg·kg-1 dimethoate simplex pollution.