改良剂对污染土壤上蔬菜生长及吸收重金属的影响

通过盆栽试验研究了石灰、钙镁磷肥、海泡石3种改良剂对重金属As、Cd、Pb和Zn复合污染土壤上蔬菜生长及其吸收重金属的影响,并表征了土壤有效态重金属含量、pH及脲酶活性等指标变化。研究结果表明,施加石灰和钙镁磷肥可以促进蔬菜生长,其中,石灰处理下小白菜生物量较对照提高了99.0%;石灰和钙镁磷肥处理下,西红柿茎叶生物量分别比对照提高了80.7%和82.3%。施用改良剂提高了土壤pH和脲酶活性,土壤有效态重金属含量不同程度降低,特别是海泡石的后期修复效果明显。与对照相比,石灰和钙镁磷肥处理显著降低小白菜叶中As含量,明显抑制西红柿茎叶对As、Cd和Pb的吸收(p<0.05);施加石灰明显降低小白菜叶中Cd和Pb含量(p<0.05)。然而,海泡石对抑制蔬菜吸收重金属的效果不明显。石灰和钙镁磷肥能有效抑制重金属从蔬菜根部向地上部转运,可作为重金属污染土壤上种植农作物优先考虑施用的改良剂。

Effect of Amendments on Vegetable Growth and Uptake of Heavy Metals from Contaminated Soils

Pot e xperiment was done to study the effect of different types of soil amendments including lime,calcium magnesium phosphate and sepiolite on growth and heavy metal uptake of green Chinese cabbage(Brassica chinensis L.)and tomato(Solanum lycopersicum L.)grown on soils contaminated with As,Cd,Pb and Zn.Changes of pH value,concentrations of available heavy metals and urease activity in soil were also investigated.Results showed that application of amendments to soils could stimulate the growth of vegetable.Leaf biomass of green Chinese cabbage treated with lime was increased by 99.0% and shoot biomass of tomato at the treatments with lime and calcium magnesium phosphate were enhanced by 80.7% and 82.3% as compared to the controls respectively.Adding soil amendments could increase soil pH value and urease activity,and reduce the concentrations of available As,Cd,Pb and Zn in soils.Especially for sepiolite,the effect in reducing heavy metal availability was better than other amendments in the later cultivation period.Concentrations of As in leaves of green Chinese cabbage,and As,Cd and Pb in shoots of tomato grown on soils added with lime and calcium magnesium phosphate were significantly lower than those in the control plants.Moreover,leaf concentrations of Cd and Pb in green Chinese cabbage at treatments with lime were significantly less than those of the controls.However,the effect of sepiolite on uptake of heavy metals by vegetables was not obvious.Addition of lime and calcium magnesium phosphate could effectively hinder the translocation of heavy metals from roots to shoots of vegetables,thus were useful for the growth and safe quality of vegetables grown on soils contaminated by heavy metals.