基于通径分析的土壤性质与硒形态的关系——以黑龙江省主要类型土壤为例

黑龙江省是缺硒(Se)比较严重的省份之一,位于全国低Se带的始端。本文选择黑龙江省不同类型土壤,采用连续浸提法测定了土壤中Se的形态,并运用通径分析法研究了土壤理化性质对土壤Se形态、全Se的影响。结果表明:总Se含量在不同类型土壤中差异较大,整体上处于中等偏低水平;各结合态Se中以有机态和残渣态为主,分别占8.16%~50.5%和26.32%~70.90%,酸溶态占0.80%~33.97%,而水溶态与交换态仅占0.70%~7.18%和0.75%~9.37%。通径分析显示,土壤理化性质通过直接和间接作用共同影响着土壤各赋存形态Se的含量和分解转化方向,但其各自的作用机理和影响强度不同。在土壤各性质中,土壤有效铁、锰和黏粒以及它们间的共同作用决定了土壤Se形态分布,其中,土壤有效铁对于除残渣态Se之外的4种形态Se的生成转化起到了主导作用,而土壤有机碳、pH等其他性质主要通过正或负的间接作用影响Se形态。土壤总Se方面,土壤有效铁、锰及黏粒含量对总Se有较强的富集作用,但土壤有机碳和pH等因素间的相互作用也不可忽略。

Relationship Between Soil Physico-chemical Properties and Selenium Species Based on Path Analysis

Samples of different kinds of soils were collected from Heilongjiang Province for analysis of Selenium (Se) species using a sequential extraction method. Se in soils may be partitioned into: 1) water soluble Se (SOL-Se), 2) exchangeable Se and Se bound to carbonate (EX-Se), 3) Acid soluble Se (FMO-Se), 4) Se bound to organic matters (OM-Se), 5) residual Se (RES-Se). Relationships between soil physico-chemical properties and Se species were investigated with path analysis. Results showed that total Se content in the soils from the province was low, but varied with soil types. In terms of Se species, Se in the soils existed mainly in the forms of OM-Se and RES-Se, which accounted for 8.16%–50.5% and 26.32%–70.90% of total Se, respectively. FMO-Se accounted for 0.80%–33.97%, but SOL-Se and EX-Se only accounted for 0.70%–7.18% and 0.75%–9.37% of total Se in the soils, respectively. The results of path analysis indicated that soil properties affected transformation direction and contents of Se species directly or indirectly, but their influencing mechanisms were different. Soil available iron (aFe) showed stronger positive effects on MO-Se, FMO-Se, SOL-Se and EX-Se. The contents of aFe, available Mn (aMn) and clay as well as the interaction among them determined largely the distribution of Se species in the soils. Soil organic carbon (SOC) and pH had indirect impacts on Se forms positively or negatively. The contents of aFe, aMn and clay also showed stronger direct impacts on soil total Se content. The interaction between soil SOC and pH could have certain influence on soil total Se.