重金属污染对土壤颗粒态有机质和添加植物材料矿化的影响

    为了解重金属污染对土壤中有机物质和添加植物材料矿化的影响,采用室内培养试验,研究不同重金属含量的植物残体进入不同程度重金属污染土壤后土壤颗粒态有机物质矿化、微生物生物量和颗粒态有机质的动态变化.结果表明,土壤和植物残体重金属污染都会减弱颗粒态有机物质和植物材料在土壤中的矿化速率,增加颗粒态有机质对微生物的抵抗能力和颗粒态有机质在土壤中的积累.在植物残体矿化过程中.土壤微生物生物量主要与土壤污染程度有关,随土壤重金属污染程度的增加而减少;当加入土壤的植物材料重金属含量较低时,中量重金属污染可在一定程度上增加土壤的呼吸强度;而土壤颗粒态有机质的积累均随土壤或植物残体中重金属的积累而增加.其中植物中重金属积累对其影响更为明显.重金属在土壤颗粒态有机质中的积累可能是土壤有机质稳定的重要原因之一.

Effect of heavy metal pollution on mineralization of soil particulate organic matters and added plant materials

In order to understand the effect of heavy metal pollution on mineralization of soil organic matter and added plant materials, incubation experiments were conducted to study dynamics of mineralization and accumulation of particulate organic matter (POM) and microbial biomass C in three soils amended with three different plant materials. The tested soils and plant materials contained different levels of heavy metals. The results show that the high concentration of heavy metals accumulated in polluted soils slowed down the rate of C mineralization of the POM and added plant materials, enhanced the capacity of the POM resistant to biodegradation,and thus increased accumulation of particulate organic matter. The microbial biomass C of the soils decreased with increasing the pollution degree of heavy metals of the soils. When soils were amended with low heavy metals-contained plant material, medium accumulation of heavy metals in the soils could increase the intensity of CO2 respiration. The accumulation of the POM increased with increasing accumulation of heavy metals in the soils and plant materials. The heavy metal pollution of the plant materials had greater effects on accumulation of the POM than that of the soils. The results found that heavy metals were significantly enriched in the particulate organic matter. The enrichment is linked to the declined rate of organic matter mineralization and the increased stability of the POM in the soils.