外加镉处理下生物质炭对土壤微生物碳代谢功能多样性的影响

Effects of biochar on carbon metabolic capacity and functional diversity of soil microbial communities under Cd contamination

采用Biolog-Eco微平板法,通过模拟实验探究外源Cd胁迫下不同量(0%、2.5%、10%,W/W)秸秆生物质炭输入后土壤微生物在碳代谢功能方面的响应机制。平均吸光度(AWCD)值、多样性指数、碳源利用特征和主成分分析结果均表明:Cd污染条件下,生物质炭的施用提高了土壤中微生物群落碳源代谢活性及功能多样性,2.5%生物质炭处理下的提高效果尤为显著。土壤微生物Mc Intosh指数上升了70.59%,群落物种均一度发生巨大的变化;土壤微生物对羧酸类、氨基酸类碳源化合物的利用能力分别提高了10倍和5倍,其中2.5%低质量分数生物质炭提高了土壤微生物对羧酸类和糖类碳源化合物利用率,10%高质量分数生物质炭却提高了氨基酸类碳源化合物的利用率。进一步分析显示,羧酸类、其他类和聚合物类碳源化合物促使两个生物质炭处理组与单加Cd对照组在碳源利用率上存在差异。

Cadmium（Cd）contamination in farmland ecosystems has become more and more serious. Biochar（BC）are known to bind heavy metals. Whether BC affects the functional diversity of soil microbial communities in Cd-contaminated soil is unclear. Here a pot experiment was designed to investigate the effects of BC on carbon metabolic capacity and functional diversity of soil microbial communities in Cd contaminated soil, using Biolog-Eco micro plate. Application rates of BC were 0%, 2.5%, and 10%（W/W）. The AWCD（average well color development） values, diversity index, carbon source utilization characteristics, and the principal component analysis results all showed that though the degree to which the soil microbes in four treatments used carbon sources was different, applying BC generally improved carbon metabolic activity and functional diversity of microbial communities in Cd contaminated soil, with 2.5% BC having the greatest effects.Compared with the control, Mc Intosh index of soil microbes was increased by 70.59% and the uniform degree of the species in the coenosis experienced huge changes. The utilization ability of carboxylic acid and amino acid carbon source compounds was increased by 10 times and 5 times, respectively. However, such utilization ability of carboxylic acid and saccharide carbon source compounds was increased at low rates of BCs（2.5%）; while that of amino acid carbon source compounds was elevated at high concentration of BCs（10%）. The difference between two BC treatment groups and the control treatment group was mainly caused by carboxylic acid, polymer and other carbon source compounds.