Lazzaro A, Schulin R, Widmer F, Frey B
Soil Sciences, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.
Sci Total Environ. 2006 Dec 1;371(1-3):110-24. doi: 10.1016/j.scitotenv.2006.08.033. Epub 2006 Oct 4.
This study investigates the effects of Pb during time on the bacterial communities of forest soils using water-extractable Pb concentrations in the soil solution as predictors of Pb bioavailability. In a microcosm experiment we applied increasing concentrations of Pb(NO(3))(2) solutions (0.5, 2, 8, 32 mM) to 5 forest soils of pH<5 and to a calcareous soil of pH>6.5. Sampling of the microcosms was performed after 3, 30 and 90 days of incubation. Community analysis included basal respiration rates and changes in the structure of the bacterial communities through T-RFLP fingerprinting. We also investigated functional stability in terms of resistance, expressed as the effects on basal respiration after 3 days of incubation, and of resilience, expressed as the recovery of bacterial community structure and of respiration rates after 90 days of incubation. Water-extractable Pb increased with time in most of the soils, in parallel with an increase of water-extractable dissolved organic carbon (DOC). The increased concentrations slightly affected bacterial community structure, although OTU (operational taxonomic unit) richness was not significantly reduced with Pb concentrations in any of the soils. The highest Pb treatment (32 mM) caused significant effects on basal respiration in some of the acidic soils, but no clear trend was observed in relation to increased Pb bioavailability with time. Resistance to Pb additions was evident in five of the six soils, but only two showed resilience after 90 days. This is the first study showing the effects of time on Pb bioavailability in soils and on the resulting reactions of the soil microbial communities.
本研究以土壤溶液中可水溶提取的铅浓度作为铅生物有效性的预测指标，调查了随时间变化铅对森林土壤细菌群落的影响。在一项微观实验中，我们将浓度递增的硝酸铅溶液（0.5、2、8、32 mM）施加到5种pH值小于5的森林土壤和1种pH值大于6.5的石灰性土壤中。在培养3天、30天和90天后对微观系统进行采样。群落分析包括基础呼吸速率以及通过末端限制性片段长度多态性（T-RFLP）指纹图谱分析细菌群落结构的变化。我们还从抗性（以培养3天后对基础呼吸的影响表示）和恢复力（以培养90天后细菌群落结构和呼吸速率的恢复表示）方面研究了功能稳定性。在大多数土壤中，可水溶提取的铅随时间增加，同时可水溶提取的溶解有机碳（DOC）也增加。尽管在任何一种土壤中OTU（操作分类单元）丰富度并未随铅浓度显著降低，但浓度增加对细菌群落结构略有影响。最高铅处理浓度（32 mM）在一些酸性土壤中对基础呼吸产生了显著影响，但未观察到随时间铅生物有效性增加的明显趋势。六种土壤中有五种对添加铅具有抗性，但90天后只有两种表现出恢复力。这是第一项展示时间对土壤中铅生物有效性以及对土壤微生物群落相应反应影响的研究。
