银叶树对Pb、Cd、Cu污染模拟湿地的适应性和修复潜力

Adaptability and remediation potentials of Heritiera littoralis onto simulated wetland polluted by lead,cadmium and copper

【目的】探究银叶树(Heritiera littoralis)对重金属污染湿地环境的修复潜力。【方法】以银叶树为研究对象,在盆栽条件下模拟湿地环境,以不添加重金属为对照(CK),探究T_(1)(50 mg·L^(-1)Pb+5 mg·L^(-1)Cd+100 mg·L^(-1)Cu)、T_(2)(100 mg·L^(-1)Pb+10 mg·L^(-1)Cd+200 mg·L^(-1)Cu)、T_(3)(200 mg·L^(-1)Pb+20 mg·L^(-1)Cd+400 mg·L^(-1)Cu)3个复合污染水平(处理)对银叶树幼苗生长、养分吸收及Pb、Cd、Cu累积量的影响。【结果】与CK相比,T_(1)对银叶树根部生物量无显著影响,而T_(2)、T_(3)显著抑制根部生物量生长,3个处理银叶树的株高、地上生物量、总生物量与CK无显著差异;T_(1)处理银叶树的耐性系数为103.96%,T_(2)、T_(3)处理分别降至95.18%、80.80%;3个处理银叶树的N、P、K吸收量无显著变化。随着重金属含量的提高,银叶树对Pb、Cd、Cu的吸收量均不断增加,且大部分储存在根部;3个处理银叶树对Pb、Cu的转运系数较对照均显著下降,对Cd的转运系数则呈现先上升后下降的变化趋势。熵权TOPSIS模型评价结果表明,T_(3)处理银叶树的修复潜力最好,T_(2)、T_(1)次之。【结论】银叶树对复合重金属污染湿地的适应性较高,但高浓度重金属显著抑制根系生长;在ρ(Pb)≤50 mg·L^(-1)、ρ(Cd)≤5 mg·L^(-1)、ρ(Cu)≤100 mg·L^(-1)的重金属污染湿地中,银叶树生长不受影响。

【Objective】The remediation potential of Heritiera littoralis on heavy metal polluted wetland was investigated.【Method】Polluted wetland environment was stimulated by irrigating different levels of lead(Pb),cadmium(Cd)and copper(Cu)solutions,including T_(1)(Pb 50 mg·L^(-1),Cd 5 mg·L^(-1),Cu 100 mg·L^(-1)),T_(2)(Pb 100 mg·L^(-1),Cd 10 mg·L^(-1),Cu 200 mg·L^(-1)),T_(3)(Pb 200 mg·L^(-1),Cd 20 mg·L^(-1),Cu 400 mg·L^(-1))and CK(tap water)to potted wetland sediments where H.littoralis were grown.Then the effects of combined pollution on the growth,nutrient uptake,and Pb,Cd and Cu accumulation of H.littoralis were analyzed.【Result】Compared with CK,root biomass of H.littoralis was not affected by T_(1) but significantly inhibited by T_(2) and T_(3);apart from this,the plant height,aboveground biomass and total biomass of the 3 treatment groups were not significantly different from CK.Although its tolerance index was down to 95.18%in T_(2) and 80.80%in T_(3) in comparison to the counterpart(103.96%)in T_(1),the nitrogen,phosphorus and potassium uptakes by H.littoralis were not significantly affected by the pollutions compared to CK.With the increase of heavy metals loads,the assimilations of Pb,Cd and Cu by H.littoralis rose continuously,predominantly accumulated in the roots.The transfer factors of Pb and Cu of the treatment groups were significantly lower than that of the CK,and that of Cd firstly increased and then declined with increased heavy metal concentrations.Entropy-weighted TOPSIS model further showed that H.littoralis demonstrated the best remediation potential in T_(3),followed by T_(2) and T_(1).【Conclusion】H.littoralis was well adapted to heavy metals polluted wetland environment,but its root growth was significantly inhibited in excessive heavy metals polluted environment;its growth was not adversely affected when the contents of Pb,Cd and Cu were equal or less than 50,5 and 100 mg·L^(-1),respectively.