生物质对赤泥壤质化改良的促进作用

Effect of biomass on soil amelioration of red mud

为解决赤泥的规模化安全处置问题,以拜耳法赤泥为研究对象,选用玉米秸秆为改良剂,通过分析各改良处理的基本理化指标、土壤酶活性以及微生物群落代谢水平等指标的变化,探究了生物质改良对赤泥壤质化改良的促进作用。结果表明,生物质添加可显著降低赤泥的盐碱性。其中,pH、电导率(EC)和盐碱度(Exchangeable sodium saturation percentage,ESP)分别降至9.89、0.461 mS·cm^(−1)和35.2%,且随添加比例的增加改良效果更佳。经生物质添加处理,赤泥基质容重显著降低、孔隙度显著增加,颗粒平均重量直径(Mean weight diameter,MWD)增加至0.38 mm。经生物质改良处理,赤泥中微生物群落的生长代谢水平、多样性以及土壤脲酶、磷酸酶和脱氢酶的活性均有显著升高。冗余分析(Redundancy analysis,RDA)结果表明,微生物群落多样性参数与pH、EC和ESP呈负相关,与MWD呈正相关。本研究结果可为赤泥规模化生态处理提供参考。

To explore the large-scale safe disposal of red mud produced by the Bayer process of bauxites,the soil amelioration of biomass on red mud was evaluated by amending the crashed cornstalk over a year of outdoor cultivation.The physico-chemical and biological properties of the amended red mud were determined regularly,including pH,EC,EPS,bulk density,aggregates distribution,soil enzyme activity and microbial indicators.The results showed that,the addition of biomass could reduce the alkalinity and salinity of red mud significantly(p<0.05),and with increase of biomass addition,the pH,EC and ESP(Exchangeable sodium saturation percentage)of red mud decreased to 9.89,0.461 mS∙cm^(−1) and 35.2%,respectively.Biomass addition could significantly improve the bulk density and porosity of red mud by increasing the mean weight diameter(MWD,up to 0.38 mm)of red mud matrix particles.The microbial metabolic levels and diversity,as well as soil enzyme activities were significantly increased with the amendment of cornstalk biomass(p<0.05).The further redundancy analysis indicated that the selected biological indicators were significantly negative to the alkaline indexes(to pH,EC,and ESP)and positive to MWD.The results of this study can provide the basis for largescale soil amelioration of red mud.