Individual and combined inhibition of phenol and thiocyanate on microbial activity of partial nitritation

This study evaluated the individual and interactive effect of phenol and thiocyanate (SCN⁻) on partial nitritation (PN) activity using batch test and response surface methodology. The IC₅₀ of phenol and SCN⁻ on PN sludge were 5.6 and 351 mg L⁻¹, respectively. The PN sludge was insensitive to phenol and SCN⁻ at levels lower than 1.77 and 43.3 mg L⁻¹, respectively. A regression model equation was developed and validated to predict the relative specific respiration rate (RSRR) of PN sludge exposed to different phenol and SCN⁻ concentrations. In the range of independent variables, the most severe inhibition was observed with a valley value (17%) for RSRR, when the phenol and SCN⁻ concentrations were 4.08 and 198 mg L⁻¹, respectively. An isobole plot was used to judge the combined toxicity of phenol and SCN⁻, and the joint inhibitory effect was variable depending on the composition and concentration of the toxic components. Furthermore, the toxic compounds showed independent effects, which is the most common type of combined toxicity.

     

不同种类食细菌线虫对石油污染土壤微生物的影响

通过在石油污染土壤中接种不同种类食细菌线虫,探究土壤微生物活性和多样性的变化.本试验设置5个处理：杀灭线虫土壤（NFS）、石油污染土壤（SP）、在石油污染土壤中分别接种不同线虫,即秀丽隐杆线虫（Caenorhabditis elegans,SPN1）、头叶属线虫（Cephalobus persegnis,SPN2）和小杆属线虫（Rhabditis marina,SPN3）.结果表明,经过168d试验,和NFS相比,SP的土壤基础呼吸和脲酶活性增大,而微生物量碳含量和蔗糖酶活性减小.和SP相比,SPN1、SPN2、SPN3的基础呼吸增大,微生物量碳减少了34.59%~72.48%,蔗糖酶活性增加了15.66%~22.89%.SP、SPN1、SPN2和SPN3的微生物的丰富度（S）分别下降了5.00,7.25,2.50和9.75,Shannon-Wiener指数（H'）分别显著下降了0.18,0.15,0.15和0.23.不同种类的食细菌线虫可通过捕食作用对石油污染土壤微生物活性及多样性产生影响并有种间差异,有利于提高石油污染土壤微生物活性,促进石油降解.     

三峡库区土壤中硒、碘、氟分布特征与规律研究

利用土壤表层样分析成果,研究了三峡库区土壤中硒、碘、氟等生命元素在不同土壤中的含量分布特征,探讨了不同地貌、植被覆盖条件下对其元素分布的影响,结果表明：三峡库区土壤的硒、碘含量较低,而氟含量较高,是低硒、低碘、高氟地区。地质背景是土壤硒、碘、氟的主要来源,灰岩分布区土壤中硒、碘、氟含量均高于其它类母岩分布区土壤,泥岩分布区硒、碘含量最低,砂岩分布区的氟含量最低。除受地质背景控制外,碘、氟还受土壤分布高程、植被等因素的影响。土壤分布高程越低,地形坡度越小,土壤中碘、氟含量越低。针叶林覆盖对土壤碘、氟起富集作用。土壤硒含量受其它因素的影响较土壤碘、氟小。