螯合剂GLDA对象草修复镉污染农田的影响

Effects of Chelate GLDA on the Remediation of Cadmium Contaminated Farmland by Pennisetum purpureum Schum

为探明螯合剂谷氨酸二乙酸四钠(GLDA)对象草修复镉(Cd)污染农田的影响,通过田间小区试验,于60 d内以不同方式(总施加量585、1170和2340 kg·hm^-2分别等分为1~4次施加,分2~4次施加的时间间隔分别为30、20和15 d)向已种植60 d象草的Cd污染农田(总Cd:0.62 mg·kg-1)施加GLDA,分析了象草地上部生物量、Cd含量和Cd提取量以及土壤pH和可溶性有机碳(DOC)质量浓度等指标.结果表明,少量且分多次施加GLDA能显著提高象草地上部生物量和Cd含量,其中分施次数和总施加量分别是生物量和Cd含量的关键影响因子;Cd提取量在总施加量585 kg·hm^-2分4次施加时最高,为16.78 g·hm^-2,较CK(不施加GLDA)显著提高275.39%;土壤pH、DOC质量浓度和DTPA-Cd含量与总施加量和分施次数存在显著正相关关系;DOC质量浓度是影响DTPA-Cd含量的主要因素;土壤总Cd含量在总施加量585 kg·hm^-2分4次施加时可较种植象草前土壤降低3.23%.因此,在利用象草修复Cd污染农田时,施加GLDA具有重要意义,且需合理选择施加方式.

In order to clarify the effects of chelate tetrasodium glutamate diacetate(GLDA)on the remediation of cadmium(Cd)contaminated farmland by Pennisetum purpureum Schum,GLDA was applied in different methods within 60 days:total application doses of 585,1170,and 2340 kg·hm^-2 were equally divided into 1-4 applications,respectively,and the time intervals of 2-4 applications were 30,20,and 15 days,respectively.The biomass,Cd content,and amount of Cd extracted from aboveground parts of Pennisetum purpureum Schum,in addition to the pH,dissolved organic carbon(DOC)mass concentration,and other indicators in soil were analyzed.The results showed that the biomass and Cd content of the aboveground parts of Pennisetum purpureum Schum increased significantly when GLDA was applied many times at a low application dose.The number of applications and the total dose were the key factors influencing the biomass and Cd content,respectively.The highest amount of Cd extracted was 16.78 g·hm^-2 at 585 kg·hm^-2(applied four times),which was 275.39%higher than the CK treatment(i.e.,no GLDA was applied).There was significant positive correlations between the pH,mass concentration of DOC,and content of DTPA-Cd,and the total dose and number of applications.The mass concentration of DOC was the main factor affecting the DTPA-Cd content.The total Cd content in the soil(after at 585 kg·hm^-2 was applied four times)decreased by 3.23%compared with that of the soil before planting Pennisetum purpureum Schum.Therefore,the application of GLDA is of great significance for the remediation of Cd contaminated farmland by Pennisetum purpureum Schum,and the application method should be selected reasonably.