石灰组配有机改良剂对农田铅镉污染土壤微生物活性的影响

Effects of Lime Mixed with Organic Modifiers on Microbial Activity in Lead and Cadmium Contaminated Farmland Soil

农田铅(Pb)、镉(Cd)污染已成为危害全球土壤环境质量的主要问题之一,开展安全有效的Pb、Cd污染土壤修复材料研究对保障农产品安全及人体健康具有重要意义.采用室内盆栽试验,探讨0.2%石灰配施不同剂量(1%、2%和5%)的腐殖酸或生物质炭对Pb、Cd污染土壤有效态Pb、Cd含量,以及对基础呼吸强度、微生物量碳含量和土壤酶活性的影响.结果表明:①与CK(不施加改良剂,对照组)相比,两种组配改良剂处理均能显著降低污染土壤有效态Pb、Cd含量,以石灰配施5%生物质炭效果最佳,其有效态Pb、Cd含量较CK分别降低了96.30%和98.10%.②石灰配施腐殖酸或生物质炭均能显著提高土壤基础呼吸强度和微生物量碳含量.③两种组配改良剂处理均会促进土壤脲酶和过氧化氢酶活性,其中石灰配施2%生物质炭对土壤脲酶活性的促进作用最显著,较CK最大提高了47.42%;石灰配施5%生物质炭对土壤过氧化氢酶活性的促进效果最佳,较CK最大提高了113.56%.④相关分析表明,土壤基础呼吸强度、土壤过氧化氢酶活性均与土壤有效态Pb、Cd含量呈极显著负相关(p<0.01);土壤蔗糖酶活性与土壤有效态Pb、Cd含量均呈极显著正相关(p<0.01).研究显示,应用石灰配施腐殖酸或生物质炭对土壤重金属有效态含量有显著降低作用,对土壤微生物基础呼吸强度、土壤微生物量碳含量及相关土壤酶活性均有增强作用.

Lead(Pb)and cadmium(Cd)contamination in farmland has become one of the major problems that endanger global environmental quality.Therefore,it is of great significance to carry out research on safe and effective remediation materials for Pb and Cd contaminated soil to ensure the safety of agricultural products and human health.The effects of mixing lime(0.2%)with different concentrations of humic acid or biochar(1%,2%and 5%)on soil available Pb and Cd content,basal respiration rate,microbial biomass carbon content and soil enzyme activity were studied using indoor pot experiment.The results showed that:(1)Compared with the CK(the control group),the available Pb and Cd content in contaminated soil was significantly reduced after treatment with two groups of modifiers.The effect of mixing lime with 5%biochar was better than other treatments,and the available Pb and Cd contents were about 96.30%and 98.10%lower than those of the CK,respectively.(2)The soil basal respiration rate and microbial biomass carbon content could significantly increase by mixing lime with humic acid or biochar.(3)Mixing lime with humic acid or biochar both could promote soil urease and catalase activities.The effect of mixing lime with 2%biochar on soil urease activity was better than other treatments,and the highest increase was about 47.42%higher than that of the CK.The effect of mixing lime with 5%biochar on soil catalase activity was better than other treatments,and the highest increase was about 113.56%higher than that of the CK.(4)The relevant analysis showed that significant negative correlations(p<0.01)existed between soil basal respiration rate,soil catalase activity and soil available Pb and Cd content,and significant positive correlations(p<0.01)existed between soil sucrase activity and soil available Pb and Cd content.These findings indicate that adding modifier of lime and humic acid or biochar can not only significantly reduce soil available Pb and Cd content,but also increase the soil basal respiration rate,soil microbial biomass carbon content and related soil enzyme activities.