采集我国北方5个典型污灌区0~20 cm土壤,添加250 mg·kg-1的Pb进行盆栽试验,测定不同污罐区土壤中两种不同敏感性小麦对Pb吸收、转化特征,同时利用离子色谱仪及WHAM 6.0化学模型对污灌区土壤溶液性质及自由Pb2+进行测定,探究污灌区土壤中小麦对Pb吸收的主控因子及其预测模型。结果表明,不同污灌区土壤中两种小麦对Pb的富集系数(BCF)及Pb的根-茎叶转运系数(TF)均有显著(P〈0.05)差异,Pb敏感性品种轮选987根与茎叶的富集系数均明显高于耐Pb品种白麦126。山东棕壤中小麦对Pb的富集系数最大,而天津潮土的最小,最大相差255.9%;Pb污染土壤中小麦对Pb的富集系数及根-茎叶转运系数(TF)均大于相应的对照处理土壤。小麦根、茎叶中Pb含量与土壤溶液中自由Pb2+含量呈极显著正相关(P〈0.01),线性拟合方程分别为:y=0.772x+54.805(R2=0.904),y=0.087x+12.980(R2=0.897);基于土壤主控因子的小麦Pb吸收模型表明,不同污罐区土壤小麦中Pb和土壤溶液自由Pb2+含量与土壤pH、OC含量呈负相关,而与土壤溶液Cl-、Na+离子含量呈正相关。除了受土壤主要因子影响外,土壤中Cl-、Na+含量升高将增加污灌土壤中Pb的环境风险。
Five typical kinds of sewage irrigated surface(0~20 cm)soils from North China were collected. The soils were added with 250mg·kg-1Pb with Pb NO_3 solution and a pot experiment was conducted to study the bioconcentration factors(BCF), root to shoot translocation coefficient(TF)of Pb by wheat characteristed with different sensitivity to Pb in different treated soils. To investigate the factors affecting the bioavailability of Pb in soils, the soil solution properties of sewage irrigation soil and the forms of Pb in solution(free Pb~(2+))were determined using ion chromatography and WHAM6.0 model. The results showed that significant differences(P〈0.05)were found for the bioconcentration factors(BCF)of Pb uptake by two kind of wheat, the root to shoot translocation coefficient(TF)of Pb by the wheat cultivars in different sewage irrigated soils, in general, the bioconcentration factors(BCF)of Pb uptake by the wheat of Pb-sensitive cultivars LX-987 were larger than that for Pb-tolerance cultivar BM-126. The maximum BCFs of Pb in plant shoots was observed with treatment in brown soil from Shan-dong and minimum BCF with Fluvo-aquic soil from Tianjin, with a maximum variation of 225.9%, in general, the addition of Pb in soils in-creased the bioconcentration factors(BCFs)and root to shoot translocation coefficient(TFs)of Pb by the wheat cultivars as compared with that in control soils. Significant(P〈0.05)positive correlation were observed between the free Pb~(2+)in soil solutions and the concentrations of Pb in the plant roots and shoots, a significant negative correlation(P〈0.001)was observed between the Cd concentrations of plant roots and shoots, the linear equation were y=0.772x+54.805(R2=0.904)and y=0.087x+12.980(R2=0.897)respectively. Based on the main properties of the soils, predicted models of Pb bioavailability to wheat were developed, and the results indicated that negative correlation were found between the uptake of Pb by wheat