关中地区典型设施菜田重金属Cd、Pb污染的修复途径及机制研究

发布时间：2018-09-08 12:07

【摘要】：在前期实地调研和取样分析的基础上,以陕西关中地区的典型设施菜田种植区-咸阳、杨凌和宝鸡受重金属镉(Cd)、铅(Pb)污染的土壤为研究对象,深入研究了重金属Cd、Pb在土壤中各赋存形态的变化特征及不同形态对作物吸收Cd、Pb的贡献、影响重金属Cd、Pb在土壤中形态分布的关键土壤肥力因子；通过室内培养试验,以设施番茄为研究对象,从植株个体水平、细胞水平,探讨了风化煤、草炭和生物炭对设施菜田重金属Cd、Pb污染土壤修复的可行性及作用机理。获得的主要研究结果如下：(1)咸阳、杨凌和宝鸡的设施菜田土壤中Pb的分布规律一致：残渣态(68.56%～75.71%)铁锰氧化物结合态(13.51%～15.92%)有机结合态(8.02%～11.79%)碳酸盐结合态(1.86%-3.81%)交换态(0.00%～0.03%)；Cd主要以碳酸盐态和铁锰氧化物结合态两种形态存在,占总量的50%以上,其次是有机结合态,残渣态和交换态所占比例较低。(2)咸阳、杨凌和宝鸡设施番茄果实中的Cd累积量主要取决于土壤中Cd交换态和Cd碳酸盐结合态的比例；在杨凌和宝鸡设施种植区,番茄果实Cd累积量与土壤Cd残渣态呈强负相关关系。(3)土壤中速效磷、速效钾和碱解氮是影响重金属Cd交换态和Cd碳酸盐结合态的关键正因子；土壤pH和阳离子交换量是影响Cd交换态的关键负因子。土壤中Pb形态分布与土壤肥力因子的相关性在不同地区呈现不同规律。(4)风化煤降低了Pb单一和Cd、Pb复合污染对番茄植株的胁迫作用,并通过提高叶片SOD活性,增强番茄植株对Cd胁迫的抗逆能力;草炭降低了Pb单一和Cd、Pb复合污染对番茄植株的胁迫作用,并通过提高叶片SOD活性,增强番茄植株对Cd胁迫的抗逆能力；生物炭通过提高叶片SOD活性来增强番茄植株对Cd胁迫修复作用,通过提高叶片POD活性来增强番茄植株对Pb单一和Cd、Pb联合胁迫的修复作用。(5)重金属Cd、Pb对番茄植株有较强的毒害作用。风化煤、草炭和生物炭保证了番茄叶片细胞的基本形念和结构完整,降低了Cd、Pb对番茄植株的损伤,均对Cd、Pb污染中番茄植株有修复作用,风化煤和草炭的修复效果优于生物炭。(6)风化煤、草炭和生物炭对土壤Cd、Pb具有良好的固定作用,并抑制了番茄地上部对Cd、Pb的累积；番茄Cd含量与土壤中Cd交换态含量呈极显著正相关关系(P0.01),番茄Pb含量与Pb交换态、碳酸盐结合态和铁锰氧化物结合态三者之和呈极显著正相关关系(P0.01)。说明风化煤、草炭和生物炭可通过降低土壤中Cd、Pb高活性态比例,以减少植株对Cd、Pb的累积。综合来看,咸阳、杨凌和宝鸡设施菜田中,Cd主要以碳酸盐结合态和铁锰氧化物结合态存在,Pb主要以残渣态形式存在,而番茄植株果实中Cd的累积量主要与土壤中Cd交换态和Cd碳酸盐结合态的含量相关。通过室内培养试验发现,风化煤、草炭和生物炭通过改变土壤pH值和对重金属的固定(吸附、络合)作用,降低了土壤中Cd、Pb高活性态比例,进而减少了植物对Cd、Pb的累积,可以作为重金属Cd、Pb污染土壤的有效修复剂。
[Abstract]:Based on the previous field investigation and sampling analysis, the soil contaminated by heavy metal cadmium (Cd) and lead (Pb) in Xianyang, Yangling and Baoji, a typical greenhouse vegetable planting area in Guanzhong area of Shaanxi Province, was taken as the research object. The variation characteristics of Cd and Pb forms in soil and their contribution to Cd and Pb uptake by crops were studied. The key soil fertility factors affecting the speciation and distribution of heavy metals Cd and Pb in soils were studied. The feasibility and mechanism of remediation of heavy metals Cd and Pb contaminated soils in greenhouse vegetable fields by weathered coal, peat and biochar were studied at individual and cell levels in laboratory. The results were as follows: (1) The distribution of Pb in the greenhouse vegetable soils of Xianyang, Yangling and Baoji was the same: residue (68.56%-75.71%) Fe-Mn oxides bound state (13.51%-15.92%) organic bound state (8.02%-11.79%) carbonate bound state (1.86%-3.81%) exchanged state (0.00%-0.03%); (2) Cd accumulation in tomato fruits of Xianyang, Yangling and Baoji facilities mainly depended on the proportion of Cd exchangeable state and Cd carbonate combined state in the soil; in Yangling and Baoji facilities, the accumulation of Cd in tomato fruits was related to soil. (3) Available phosphorus, available potassium and alkali-hydrolyzable nitrogen were the key positive factors affecting the exchangeable state of heavy metals Cd and the bound state of cadmium carbonate; soil pH and cation exchange capacity were the key negative factors affecting the exchangeable state of cadmium. (4) Weathered coal reduced the stress of Pb single and Cd, Pb compound pollution on tomato plants, and enhanced the resistance of tomato plants to Cd stress by increasing the activity of SOD in leaves; peat reduced the stress effect of Pb single and Cd, Pb compound pollution on tomato plants, and enhanced the stress of tomato plants to Cd by increasing the activity of SOD in leaves. Biochar enhanced the phytoremediation of tomato plants under Cd stress by increasing the activity of SOD in leaves, and enhanced the phytoremediation of tomato plants under combined stress of Cd and Pb by increasing the activity of POD in leaves. (6) Weathered coal, peat and biochar had good fixation effect on soil Cd and Pb, and inhibited the accumulation of Cd and Pb in tomato shoots. The content of Cd in tomato was positively correlated with the content of Cd exchangeable state in soil (P Cd and Pb accumulation in greenhouse vegetable fields of Xianyang, Yangling and Baoji were mainly in carbonate-bound and iron-manganese oxides-bound forms, while Pb was mainly in residue form. The accumulation of Cd in tomato fruits was mainly related to the contents of Cd-exchanged and cadmium-bound forms in soil. Weathered coal, peat and biochar can reduce the proportion of Cd and Pb in soil by changing soil pH value and fixing (adsorption, complexation) of heavy metals, thereby reducing the accumulation of Cd and Pb by plants, and can be used as an effective remediation agent for heavy metal Cd and Pb contaminated soil.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X53

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