土壤微生物对邻苯二甲酸二(2-乙基己)酯胁迫的生态响应

为了探讨和分析典型酞酸酯邻苯二甲酸二(2-乙基己)酯(DEHP)对土壤微生物的生态毒性效应,采用室内避光培养模拟实验,设定DEHP在土壤中的染毒浓度为0、0.1、1、10、50 mg·kg-1,取样时间为7、14、21、28 d,考察了DEHP对3种土壤酶、土壤呼吸和土壤微生物生物量碳、氮的影响。结果表明:在染毒初期,过氧化氢酶活性受到明显抑制,且随DEHP浓度增大抑制作用减弱,抑制率为25.0%~14.3%;0.1~10 mg·kg-1处理组脱氢酶活性受到显著抑制,抑制率分别为86.3%、54.7%和31.7%,但50 mg·kg-1处理组脱氢酶活性则是对照组的2.05倍;染毒前期脲酶对DEHP胁迫不敏感,染毒后期其活性受到抑制,且随DEHP浓度增大抑制作用增强;过氧化氢酶和脲酶活性随时间呈下降趋势,而脱氢酶活性随时间呈先上升后下降的趋势。此外,在DEHP的胁迫下土壤呼吸强度和土壤微生物生物量碳及生物量氮均受到刺激,且随DEHP浓度的增加均呈先升高后降低的趋势,随时间均呈下降的趋势。总体来说,DEHP胁迫下,土壤酶活性、土壤呼吸强度和微生物生物量均发生明显变化,土壤微生物生态环境受到一定影响。

Ecological effects of di(2-ethylhexyl) phthalate on soil microorganisms

Pollution by phthalic acid esters (PAEs) is becoming more and more serious in the soil environment. Here, a laboratory experiment was performed to evaluate the ecological toxicological effects of di(2-ethylhexyl) phthalate (DEHP), a typical phthalate, on some soil enzymes (urease, catalase, and dehydrogenase), respiration, and microbial biomass in soil under different DEHP rates (0, 0.1, 1, 10 mg and 50 mg DEHP per kg soil) on the 7th, 14th, 21st, and 28th day after treatments with DEHP. Results showed that soil catalase activity was significantly inhibited and decreased by 25.0%~14.3% compared with the control on the 7th day. Soil dehydrogenase activity decreased by 86.3%~31.7% at 0.1~10 mg·kg^-1 treatments but increased by 105% at 50 mg·kg^-1. However, DEHP suppressed soil urease activity more during later period than during early period. Furthermore, soil urease activity significantly decreased over time, which may relate to nitrogen contents in soil. With DEHP increasing, soil respiration and soil microbial biomass carbon and biomass nitrogen increased, but decreased at higher rates. Compared with the control, however, they were all stimulated, whereas these parameters decreased over time. In conclusion, DEHP has significant ecological effects on soil microbes.