Key Laboratory of Biogeology and Environmental Geology of Chinese Ministry of Education, China University of Geosciences, 430074 Wuhan, PR China.
J Hazard Mater. 2010 Jan 15;173(1-3):510-6. doi: 10.1016/j.jhazmat.2009.08.114. Epub 2009 Aug 31.
Microcalorimetry was applied to assess and compare the toxic effect of heavy metals, such as As, Cu, Cd, Cr, Co, Pb and Zn, on the soil microbial activities and community. About 1.0 g soil spiked 5.0mg glucose and 5.0mg ammonium sulfate, the microbial activities were recorded as power-time curves, and their indices, microbial growth rate constant k, total heat evolution Q(T), metabolic enthalpy Delta H(met) and mass specific heat rate J(Q/S), were calculated. Comparing these thermodynamic parameters associated with growth yield, a general order of toxicity to the soil was found to be Cr>Pb>As>Co>Zn>Cd>Cu. When soil was exposed to heavy metals, the amount of bacteria and fungi decreased with the incubation time, and the bacterial number diminished sharply. It illustrates that fungi are more tolerant, and bacteria-fungi ratio would be altered under metal stress. To determine the status of the glucose consumed, a glucose biosensor with eggshell membrane was used to measure the remaining glucose in soil sample. Results showed that the time at which glucose was consumed completely was agreed with the microcalorimetric time to a large extent, and depended on the toxicity of heavy metals as well.
微量热法被应用于评估和比较重金属（如 As、Cu、Cd、Cr、Co、Pb 和 Zn）对土壤微生物活性和群落的毒性效应。大约 1.0 g 土壤中加入 5.0mg 葡萄糖和 5.0mg 硫酸铵，微生物活性被记录为功率-时间曲线，并且计算了它们的指标，微生物生长速率常数 k、总热释放量 Q(T)、代谢焓变 Delta H(met)和质量比热率 J(Q/S)。通过比较这些与生长产量相关的热力学参数，发现土壤的一般毒性顺序为 Cr>Pb>As>Co>Zn>Cd>Cu。当土壤暴露于重金属时，细菌和真菌的数量随时间的推移而减少，细菌数量急剧减少。这表明真菌更具有耐受性，并且在金属胁迫下细菌-真菌比例会发生改变。为了确定消耗的葡萄糖的状态，使用带有蛋壳膜的葡萄糖生物传感器来测量土壤样品中剩余的葡萄糖。结果表明，葡萄糖被完全消耗的时间在很大程度上与微量热法的时间一致，并且也取决于重金属的毒性。
