科研之友
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摘要
Cadmium (Cd) is a toxic heavy metal, accumulated in soil by anthropogenic activities and has serious effects on soil microbial activities in contaminated soils. Moreover, there is a lack of reliable data on the effects of Cd in the soil-plant system, since most of the information on Cd-microorganism interactions in soils are based on sewage sludge without plants. The main objective of this study was to assess the effects of Cd on soil microbial activities and community structure during growth of plant. A greenhouse pot experiment was conducted to evaluate the impact of different concentrations of Cd on soil microbial activities during the growth of Chinese cabbage (Brassica chinensis) in two different soils. The field soils were used in this short-term (60 days) greenhouse pot experiment. The soils were spiked with different Cd concentrations, namely, 0, 1, 3, 8, 15, 30 mg Cd kg(-1) oven dry soil, respectively. The experimental design was a 2 (soil) x 2 (vegetation/non-vegetation) x 5 (treatments (Cd)) x 3 (replicate factorial experiment). After 60 days, the study was terminated and soils were analyzed for selected microbial parameters, such as, microbial biomass carbon (C-mic), basal respiration and phospholipid fatty acids (PLFAs). Application of Cd at lower concentrations (1 and 3 mg kg(-1)) resulted in a slight increase in C-mic, whereas Cd concentrations > 8 mg kg(-1) caused an immediate significant decline in C-mic, the ratio of C-mic to total organic C (C-mic/C-org) decreased and the metabolic quotient (qCO(2), namely, the basal respiration CO2/C-mic) increased with elevated Cd concentration. However, the impact on soil C-mic and basal respiration caused by Cd was dependent from plant cover or soil properties. The results of PLFAs showed relative increase in fatty acid indicators for fungi and actinomycetes and gradual increase in the ratio of Gram-positive to Gram-negative bacteria which were responsible for these differences with increasing Cd concentration in the planted and unplanted soils. Soil microbial parameters, including, soil C-mic, the ratio of C-mic/C-org, qCO(2), and community structure, may be sensitive indicators reflecting environmental stress in soil-Cd-plant system. However, further research work is needed for better understanding the changes in microbial community structure and actually impact on soil microbial community function.
- 出版日期2010-7
- 单位浙江大学
