甲苯对土壤芳基硫酸酯酶活性的影响

甲苯作为土壤酶测定的前处理试剂及许多有机污染物在环境中降解的中间产物,有关其对土壤酶的影响研究在土壤酶学和环境科学领域具有重要意义.因此,采用模拟方法,较系统地研究了不同剂量甲苯和处理时间下芳基硫酸酯酶活性的变化规律.结果表明,甲苯对纯酶具有明显的抑制作用,酶活性降幅最大达到45.5%;灭菌土壤对溶液中的纯酶有很强的吸附能力;极微量的甲苯即可完成对土壤中酶活性的激活作用,酶活性增幅为109%～298%;随着甲苯剂量的增加,土壤酶活性的变化幅度逐渐趋缓,并可用Langmuir模型较好地拟合,由此获得了最大表观酶活性Umax,发现其与土壤性质显著相关,说明甲苯主要是通过杀死土壤中的微生物来影响土壤酶活性的.此外,初步探讨了不同土壤中胞外酶量与胞内酶量的关系,发现在供试土样中土壤芳香硫酸酯酶胞外酶和胞内酶分别占54.4%和45.6%.本研究可为后续土壤酶测定质量的完善和提高提供依据.     

The effects of high metal concentrations in soil-compost mixtures on soil enzymes

The study was undertaken to determine the impact of high-metal composts on the activities of four soil enzymes. High concentrations of metal salts (Cr, Cu, Ni or a Co-Mo-Pb combination) were added to feedstocks during the thermophilic stage of composting. These four metal-enriched composts and an unamended control compost were then mixed with soil collected from long-term agriculture plots under organic management or conventional management. The compost-soil mixtures were prepared at two rates (1:1 or 1:3 compost:soil, v/v) and incubated at 20°C for three weeks. These 20 combinations plus the five composts and the two soils were added to pots and incubated for three weeks. Following incubation, soil enzyme activities (acid phosphatase, arysulfatase, dehydrogenase, phosphodiesterase) were measured using traditional assay procedures. Compared to the control, none of the high-metal composts inhibited soil enzyme activity. Notably, the Cu compost treatment produced significantly higher activity of all four enzymes in the soil compared to the control. Previous soil management influenced the activity of three enzymes, arysulfatase and dehydrogenase had greater activity in the organic soil while phosphatase activity was greater in the conventional soil. Increasing the proportion of compost in the pot had a positive effect on phosphodiesterase activity only. In conclusion, the high-metal compost treatments either enhanced or caused no adverse effects on soil enzyme activity.     

污水中基于酶活性分析的硫酸雌酮雌激素效应

在污水处理厂尾水中,雌酮（E1）和硫酸雌酮（E1-3-S）分别是赋存浓度最高的自由态雌激素和结合态雌激素.E1-3-S难以被生物降解且雌激素效应有限,但环境条件适宜时可在芳基硫酸酯酶（AryS）作用下通过水解释放出具有雌激素效应的E1.本论文提出了一种利用AryS活性值和E1-3-S酶促水解动力学参数计算E1-3-S半寿期的方法.根据现场取样分析得到了重庆市某污水处理厂生物处理构筑物内混合液,合流制管道溢流口与尾水受纳水体底泥中在冬、春、夏3个季节的AryS活性值,其均值分别为417.41~941.14,91.55~179.42,28.11~59.64μg对硝基酚/（g·h）.在20℃的实验室条件下,E1-3-S的酶促水解遵循一级动力学模式（P<0.01）,且水解速率K_d与AryS活性呈线性正相关（R²=0.9774）.根据春季的AryS活性数据和实验室条件下E1-3-S水解速率与酶活性的线性回归方程推算,得到了在污水处理厂生物构筑物内、合流制管网溢流口和污水厂尾水排放点附近水体中E1-3-S在对应环境温度条件下通过酶促水解的半寿期分别为33.5,153.0,410.0h.该方法可用于评估硫酸型结合态雌激素在水环境中的雌激素效应释放风险.