铬(Ⅵ)和菲单一及复合污染对土壤微生物酶活性的影响

Effects of single and joint pollution of chromium(Ⅵ)and phenanthrene on microbiological enzyme activities in soil

采集上海青浦现代农业园区稻田土壤,通过室内模拟试验,研究铬(Ⅵ)和菲单一及复合暴露对土壤微生物过氧化氢酶和脱氢酶活性的影响及交互作用方式。铬(Ⅵ)和菲单一及复合暴露对两种酶活性的影响表现出明显的浓度-效应关系,整体上随污染物浓度升高,酶活性降低,但低浓度菲对过氧化氢酶表现出略微激活效应。以暴露第7 d为评价终点,铬(Ⅵ)暴露对土壤过氧化氢酶EC10和EC20分别为203.61、471.48 mg·kg-1,菲暴露对土壤过氧化氢酶EC10和EC20分别为299.89 mg·kg-1和大于800.00 mg·kg-1,复合暴露对土壤过氧化氢酶EC10和EC20分别为116.14、349.28 mg·kg-1;铬(Ⅵ)暴露对土壤脱氢酶EC10和EC20都小于50.00 mg·kg-1,菲暴露对土壤脱氢酶EC10和EC20分别为113.63、223.49 mg·kg-1,复合暴露对土壤脱氢酶EC10和EC20都小于100.00 mg·kg-1。表明脱氢酶比过氧化氢酶更加敏感。采用酶活性净变量法评价交互作用方式,结果表明铬(Ⅵ)和菲复合污染对土壤微生物过氧化氢酶和脱氢酶的交互作用方式均表现为拮抗作用。

Soils have suffered from single or combined pollution by various pollutants including heavy metals and polycyclic aromatic hydrocarbons（PAHs）. However, the interactive and toxic effects of chromium（Ⅵ）and phenanthrene on soil microbiological enzymes activities remain unknown. In an indoor simulation test, the effects of single and co-exposure of chromium（Ⅵ） and phenanthrene on soil catalase and dehydrogenase activities were examined in a paddy soil collected from Qingpu modern agricultural park in Shanghai. There were significant correlations between enzyme activity and concentrations of chromium（Ⅵ）and phenanthrene. Basically, the enzymatic activities decreased with increasing pollutant concentrations. However, at low concentrations of phenanthrene, the activity of catalase was promoted.For catalase, the 7 d-EC10 and 7 d-EC20 values of chromium（Ⅵ） were 203.61 mg·kg^-1 and 471.48 mg·kg^-1, respectively, while those of phenanthrene were 299.89 mg·kg^-1and over 800.00 mg·kg^-1, respectively. For dehydrogenase, the 7 d-EC10 and 7 d-EC20 values of chromium（Ⅵ）were both less than 50.00 mg·kg^-1, whereas those of phenanthrene were 113.63 mg·kg^-1 and 223.49 mg·kg^-1, respectively.These results indicated that dehydrogenase was more sensitive to both chromium（Ⅵ）and phenanthrene pollution than catalase was. The interaction of chromium（Ⅵ） and phenanthrene showed antagonistic effects on catalase and dehydrogenase activities. The present findings would provide useful information for ecological risk assessments of combined pollution of soils.