氮肥协同EDDS强化三叶鬼针草修复镉污染土壤

Study on the Synergism of NitrogenFertilizer and EDDS to Enhance the Remediation of Cadmium Contaminated Soil by Bidens Pilosa L.

氮肥协同乙二胺二琥珀酸(EDDS)强化植物修复技术可应用于镉(Cd)污染土壤的修复.通过室内盆栽试验,研究了15 mg·kg^(-1) Cd胁迫下(CdCl_(2)·2.5H_2O),硝态氮(硝酸钙)、铵态氮(硫酸铵)、酰胺态氮(尿素)三种氮肥在不同浓度(25、50、75 mg N·kg^(-1))下与1 mmol·L^(-1) EDDS联合施加对三叶鬼针草(Bidens pilosa L.)幼苗修复Cd污染土壤的影响.结果表明:1)氮肥与EDDS联合作用修复Cd污染土壤,使土壤pH下降、电导率上升、全氮量显著上升,土壤过氧化氢酶和脲酶活性较原土得到显著提升.2)经EDDS处理后,土壤Cd含量下降.在EDDS+50 mg N·kg^(-1)硝态氮处理时,土壤Cd含量最低,Cd去除率达到12.44%,处理效果最好.3)经EDDS单独处理后,土壤Cd的形态发生改变,可交换态(F1)、碳酸盐结合态(F2)、有机物结合态(F4)、残渣态(F5)含量下降,铁锰氧化物结合态(F3)含量上升.在EDDS+75 mg N·kg^(-1)硝态氮处理时,F1、F2占比最大.综上所述,氮肥与EDDS联合作用能有效改善土壤理化性质,增强土壤酶活性,增加土壤有效态Cd含量.在EDDS+50 mg N·kg^(-1)硝态氮处理时,三叶鬼针草幼苗对土壤Cd污染修复效果最好.

This study aims to provide scientific basis for the application of Cd contaminated soil phytoremediation technology induced by nitrogen fertilizer and ethylenediaminedisuccinic acid(EDDS).An indoor pot experiment was conducted to study the effect of three nitrogen fertilizers,include nitrate nitrogen(calcium nitrate),ammonium nitrogen(ammonium sulfate)and amide nitrogen(urea),applied at different concentrations(25,50,75 mg N·kg^(-1))in combination with 1 mmol·L^(-1) EDDS on the remediation of cadmium contaminated soil by Bidens Pilosa L.seedlings,under the stress of 15 mg·kg^(-1) Cd(CdCl_(2)·2.5 H_(2)O).The results showed that:1)The combined action of nitrogen fertilizer and EDDS to remediate Cd contaminated soil can reduce the soil pH,increase the conductivity and the total nitrogen significantly,and soil catalase and urease activities can be significantly improved compared with the original soil.2)After EDDS treatment,the soil Cd content decreased.The Cd content in the soil was the lowest when the cadmium contaminated soil was treated with EDDS+50 mg N·kg^(-1) nitrate nitrogen,with the best treatment effect of 12.44%Cd removal rate.3)After EDDS treatment alone,the forms of Cd changed,the content of exchangeable(F1),carbonate bound(F2),organic matter bound(F4)and residue(F5)decreased and the content of Fe-Mn oxide bound(F3)increased.After the treatment of EDDS+75 mg N·kg^(-1) nitrate nitrogen,F1 and F2 accounted for the largest proportion.In summary,the combined effect of nitrogen fertilizer and EDDS could effectively improve the physical and chemical soil properties,enhanced soil enzyme activity,and increased soil available cadmium content.Bidens Pilosa L.seedlings treated with EDDS+50 mg N·kg^(-1) nitrate nitrogen had the best remediation effect on cadmium contaminated soil.