组配钝化剂对设施土壤污染镉的钝化效果及植株富集镉的影响

Passivating effect of compound passivating agent on cadmium pollution in facility soil and effects on cadmium accumulation in plant

为明确组配钝化剂对设施土壤污染镉的钝化效果,采用生物模拟方法,以外源添加镉的设施土壤为研究对象,探究骨炭粉、生物炭、纳米腐殖质组配钝化剂对设施土壤污染镉的钝化效果和对小白菜富集镉的影响。主要研究结果如下:(1)当骨炭粉、生物炭和纳米腐殖质总添加量为2%、5%,配施比例为1∶5∶2时,钝化效果最为显著。土壤有效态Cd含量显著降低,降幅为12.72%~15.73%,更易使Cd形态从弱酸提取态转化为可还原态、可氧化态和残渣态,土壤pH值显著升高0.22~0.34个单位,土壤有效磷含量显著增长15.28%~23.73%,土壤过氧化氢酶、脲酶活性显著升高,增幅分别为23.21%~52.98%、57.75%~67.75%。添加量为5%时,小白菜地上部Cd含量显著降低14.67%;总添加量为2%时,小白菜根部Cd含量显著降低14.47%。(2)其他处理也表现出了一定的钝化效果。总添加量为5%,配施比例为1∶2∶2时,土壤的有效态Cd含量显著降低了10.93%。总添加量为2%、5%,配施比例为1∶5∶5时,土壤有效态Cd含量显著降低,降幅为7.49%~7.56%。(3)通过相关性分析得出,土壤的pH值升高会降低土壤的有效态Cd含量,提高土壤有效磷含量、过氧化氢酶及脲酶活性;土壤有效态Cd含量升高会使小白菜地上部Cd含量升高,同时使土壤有效磷含量及过氧化氢酶活性降低,有效态Cd含量降低会使小白菜地上部Cd含量降低。综上所述,组配钝化剂在不同添加量及配施比例下,总体上可以有效提高土壤pH值、有效磷含量以及过氧化氢酶、脲酶活性;降低土壤的有效态Cd含量和小白菜Cd含量。此外,进一步从节约经济成本的角度进行综合分析,推荐骨炭粉、生物炭、纳米腐殖质总添加量为2%,配施比例为1∶5∶2,对Cd污染设施土壤的钝化效果最好。

In order to clarify the passivation effect of compound passivation agents on the facility soil contaminated with cadmium(Cd).The facility soil with exogenous Cd was studied.Biological simulation method was adopted to explore the passivation effect of compound passivation agents of bone charcoal powder,biochar and nano-humus on Cd accumulation in pakchoi.The main results were as follows:(1)When the total amount of bone charcoal powder,biochar and nano-humus were 2%and 5%,and the proportion was 1∶5∶2,the passivation effect was most significant.The content of available Cd was significantly decreased by 12.72%-15.73%.It was easier to convert Cd form from weak acid extraction state to reducible,oxidizable and residue state.Soil pH value was significantly increased by 0.22-0.34 units,and soil available P content was significantly increased by 15.28%-23.73%.The activities of catalase and urease in soil were significantly increased by 23.21%-52.98%and 57.75%-67.75%.When the supplemental level was 5%,the content of Cd in aboveground of pakchoi was significantly decreased by 14.67%.When the total supplemental level was 2%,the content of Cd in pakchoi root was significantly decreased by 14.47%.(2)Other treatments also showed some passivation effects.When the total addition amount was 5%,and the proportion of application was 1∶2∶2,the available Cd content in soil was significantly decreased by 10.93%.When the total addition amount were 2%and 5%,and the proportion of application was 1∶5∶5,the available Cd content in soil was significantly decreased by 7.49%-7.56%.(3)The correlation analysis showed that the increase of soil pH value would reduce the content of soil available Cd,and increase the content of soil available P,catalase and urease activities;The increase of soil available Cd content could increase the content of Cd in the aboveground part of pakchoi,and soil available P content and catalase activity decreased.The decrease of available Cd content could reduce the content of Cd in the aboveground part of pakchoi.In conclusion,under different addition amounts and proportions of application,the compound passivation agents could effectively increase soil pH value,available P content,catalase and urease activities,decrease the available Cd content in soil and Cd content in pakchoi.In addition,further comprehensive analysis was conducted from the perspective of saving economic cost.It was recommended that the total addition amount of bone charcoal powder,biochar and nano-humus was 2%,and the proportion of combined application was 1∶5∶2,which had the best passivation effect on the facility soil contaminated with Cd.