土壤镉环境行为对水分管理模式的响应差异

Response Difference of Soil Cadmium Environmental Behavior to Water Management Model

为探讨碳酸盐岩地区发育的石灰性水稻土在不同水分管理模式(60%田间持水量、淹水与干湿交替)下,外源Cd进入土壤中的形态随时间的动态响应差异,该文以石灰性水稻土为研究对象,采用室内培养,模拟3种水分环境条件,通过Tessier连续提取法对Cd的5种形态(可交换态、碳酸盐结合态、铁锰氧化态、有机结合态和残渣态)进行测定分析。结果表明,不同水分管理模式下各个时期Cd形态分布中铁锰氧化态所占比例最高;整个培养期间,不同水分管理模式下的可交换态Cd含量变化幅度较小,此外,90%以上有机结合态Cd所占比例较其他4种形态较低;外源Cd进入石灰性水稻土后,60%田间持水量比淹水和干湿交替条件下相对容易达到稳定的状态。研究中石灰性水稻土中Cd的各形态对水分管理模式的响应差异不明显,土壤重金属形态在土壤各相中的再分配及可利用性受土壤理化性质的多重因素影响。

In order to study the effects of different water management modes(60% field capacity, flooding and alternation of drying and wetting) on calcareous paddy soil in carbonate area, the dynamic response of the forms of exogenous Cd entering the soil was different with time. Taking calcareous paddy soil as the research object, indoor culture was used, five forms of Cd(exchangeable, carbonate bound, Fe Mn oxidized, organic bound and residual) were determined and analyzed by Tessier continuous extraction method under three water environment conditions. Under different water management modes, the proportion of iron and manganese oxidation in the distribution of Cd forms was the highest. During the whole cultivation period, the exchangeable Cd content under different water management modes changed slightly, and the proportion of more than 90% organically bound Cd was lower than that of the other four forms. When exogenous Cd was added into calcareous paddy soil, 60% field capacity was easier to reach a stable state than under the condition of flooding and alternation of drying and wetting. Results indicated that there was no significant difference in the response of Cd forms to water management patterns in calcareous paddy soil, the redistribution and availability of heavy metals in different soil phases are affected by multiple factors of soil physical and chemical properties.