棉杆炭对镉污染土壤小白菜生长及镉迁移的影响

Cadmium Translocation and Growth Characteristics of Pakchoi in Contaminated Soil after Application of Cotton Straw Biochar

为探索生物质炭对污染土壤-作物体系中镉迁移的钝化效果,本研究以小白菜为对象,采用盆栽试验,在土壤Cd2+水平为0、1、6、12mg/kg和棉杆炭添加量分别为0、10、20、50g/kg处理下,测定土壤pH值、小白菜株高、生物量及小白菜地上部分和地下部分中镉的含量,探究施加棉杆炭对土壤-小白菜体系中镉迁移的影响。结果表明,棉杆炭添加可短期内极显著提高土壤的pH值(P <0.01)。在不同镉污染土壤中,添加棉杆炭可以显著增加小白菜的生物量(P <0.05),尤其是10g/kg棉杆炭添加处理,极显著增加了小白菜的生物量(P <0.01)。添加棉杆炭能够有效提高小白菜的成活率,对株高影响不显著(P>0.05)。在1mg/kg土壤镉污染中,转运系数大于1,随棉杆炭量的增加,小白菜地上部分富集系数逐渐减少,地下部分的富集系数逐渐增加,说明镉从植物地下部分向地上部分转移量不断降低。在6mg/kg土壤镉污染浓度下,当棉杆炭添加量为10g/kg时,转运系数大于1,而当棉杆炭添加量大于10g/kg后,转运系数小于1,说明植物地下部分镉含量大于地上部分,棉杆炭的添加有效阻控了镉向植物地上部分的迁移。

Effects of cotton straw biochar added(0,10,20,50g/kg)on the growth of pakchoi(Brassica chinensis L.)and cadmium translocation in the different cadmium(Cd)-contaminated soils(0,1,6,12mg/kg)were studied by pot experiment to explore the effect of biochar on cadmium immobility in contaminated soil.Soil pH,the biomass of pakchoi and the content of Cd in the aboveground and underground parts of the pakchoi and the soil were determined.The results showed that the addition of biochar significantly increased soil pH in the short term.In different cadmium contaminated soils,adding biocar could significantly increase the biomass of pakchoi,especially in the10g/kg biocar addition treatment,which greatly increased the biomass of pakchoi(P<0.01).The addition of biochar could effectively improve the survival rate of pakchoi,but had no significant effect on plant height.Under cadmium content of1mg/kg in soil,the translocation factor(TF)was more than1.With the increase of cotton straw biocar content,the bio-enrichment coefficient(BCF)of aboveground part of pakchoi decreased,and BCF of underground part of pakchoi increased.At6mg/kg cadmium content in soil,when biocar was added to10g/kg,TF was more than1,and when biocar content was more than10g/kg,TF was less than1.This indicated that the cadmium content in the underground part of the plant was greater than that in the upper part of the plant.The addition of biocar effectively controlled the migration of cadmium to the upper part of plant.