云南个旧市郊农田土壤—作物系统重金属赋存形态

发布时间：2018-01-08 01:24

本文关键词：云南个旧市郊农田土壤—作物系统重金属赋存形态　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,土壤重金属污染问题日益受到人们关注。重金属在土壤中易积累、难降解,并且能够通过土壤-植物-动物-人这一系统进入人体,危害人类健康。在土壤中高含量的重金属难以快速、经济、有效去除这一现实条件下,为了保障人体健康,进一步深入研究土壤-植物系统中重金属的赋存形态,筛选适合在污染区种植的低吸收品种,并使用经济有效的土壤改良剂减少重金属的植物毒性,具有重要意义。本研究首先对云南个旧鸡街农田土壤和农作物中5种重金属(As、Pb、Cd、 Cu、Zn)的总量和形态进行野外调查；其次,通过室内盆栽实验从重金属高吸收蔬菜中筛选出低吸收品种,并进一步研究同一种蔬菜不同重金属吸收能力品种之间重金属形态分布的差异；最后,研究了不同改良剂对降低土壤重金属生物有效态、蔬菜重金属吸收和品质(可溶性蛋白、可溶性糖、游离氨基酸和维生素C含量)的影响。论文主要研究结果如下：(1)研究区农田土壤以Cd-Pb-As复合污染为主,其中土壤中Cd和Pb有效态高达39.12%和36.28%。对蔬菜可食部位的富集系数进行聚类分析结果表明,青菜(Brassica chinensis Cruciferae)、薄荷(Mentha haplocalyx Labiatae)、香菜(Coriandrum sativum Umbelliferae)的叶片能够大量积累5种重金属,已不适合在污染区种植。同时,选择了可食部位重金属浓度最高的3种不同类型蔬菜进行重金属形态分析,结果表明As主要以乙醇提取态和残渣态存在,Pb主要以氯化钠和残渣态存在,Cd主要以醋酸态和残渣态存在,Cu和Zn的主要存在形态分别为氯化钠和醋酸提取态,说明5种重金属中As的毒性效应最高。此外,蔬菜中5种重金属的综合污染指数为Pb As Cd Zn Cu。虽然土壤中Cd的有效态高达39.12%,但在蔬菜中Cd却以生物活性相对较低的醋酸提取态和残渣态存在。居民经食用蔬菜日摄入Cd是暂定每日耐受摄入量(PTDI)的1.86倍,远低于Pb(5.71倍)和As(5.12倍)。总起来看,与Cd相比,Pb和As对当地居民的生命健康构成了更大威胁。(2)筛选低吸收蔬菜品种的盆栽实验结果表明,同种蔬菜不同品种间的株高和生物量存在显著差异。对于As轻度污染土壤而言,实验中的27个蔬菜品种可食部位砷含量均未超过As最大允许浓度(As-MPC);对铅而言,只有部分品种可食部位Pb含量低于Pb-MPC,而所有品种可食部位Cd含量均超过Cd-MPC。这说明本盆栽实验土壤中Pb和Cd污染严重,尤其是Cd。筛选结果表明：对于实验所用的As-Pb-Cd复合污染土壤,绿秀848菠菜(S3)、粉杆青菜(P4)、春城3号莴笋(A11)和靓马长茄(A1)与其他同类蔬菜相比,其吸收重金属的能力更弱,属于相对安全的品种。对同种蔬菜可食部位重金属含量差异明显的品种进行形态分析的结果表明：对As而言,低吸收菠菜叶片(S6)中以低活性形态存在；莴苣品种无论砷吸收高低,均以低活性形态存在,在低吸收品种A15中尤为明显。对Pb和Cd而言,高吸收菠菜品种(S3)叶片以低活性形态存在,低吸收菠菜品种(S6)叶片却以高活性形态存在；低吸收茄子品种A4中Pb以低活性形态存在。因此,在重金属低吸收品种筛选中应注意避免体内金属形态以高生物活性存在的情况。(3)添加改良剂能够改变复合污染土壤中重金属生物有效态。本实验中大多数正交处理能显著降低土壤中重金属生物有效态,其中处理7、9和10能显著降低土壤As有效态,处理7、9、10、13和14能显著降低土壤Pb有效态,处理9、10、11和13能显著降低土壤Cd有效态。此外,值得注意的是,处理9和10能显著降低土壤中3种重金属的有效态,这表明中等浓度熟石灰(5g kg-1),低浓度有机肥(0-25 g kg-1)和中高浓度粉煤灰(10-15 g kg-1)能有效改良As-Pb-Cd复合污染土壤。与对照相比,处理9和10土壤有效态和青菜可食部位As含量均有显著降低,处理10和13土壤有效态和青菜可食部位Cd含量均有显著降低。此外,添加改良剂能够促进青菜的生长、株高和生物量,其中促进作用最显著的是16号处理。大多数改良处理能提高青菜品质,表现在可溶性蛋白、可溶性糖、游离氨基酸和维生素C含量能保持或增加。最后,青菜体内重金属的形态分析结果表明：在叶片和茎中,砷主要以Fethanol+Fwater形态存在,Cd主要以FNaCl+ FHAc形态存在。
[Abstract]:In recent years, the soil heavy metal pollution problem has been concerned by people. The heavy metal accumulation in soil degradation, and can enter the system of human body through the soil plant animal, harm to human health. The high content of heavy metals in soil is fast, economic and effective removal of this realistic condition, in order to protect the health of the human body, further study on the speciation of heavy metals in the soil plant system, suitable for screening low absorption varieties planted in the contaminated area, and the use of soil amendments can effectively reduce the toxicity of heavy metals in plant economy, has important significance. In this study, the first of the 5 Yunnan old chicken Street of heavy metals in soils and crops (As Pb, Cd, Cu, Zn), the amount and form of field investigation; secondly, by pot experiment from the heavy metal absorption screened low absorption varieties of vegetables, and further study the same Vegetable distribution of heavy metals in the form difference between different varieties of heavy metals; finally, study the different modifier to reduce the bioavailability of heavy metals in soil, heavy metal uptake and quality of vegetables (soluble protein, soluble sugar, free amino acid and vitamin C content) effects. The main results are as follows: (1) the study area of farmland the Cd-Pb-As compound pollution soil, enrichment coefficient of which soil Cd and available Pb reached 39.12% and 36.28%. on vegetable edible part of cluster analysis showed that the vegetables (Brassica chinensis Cruciferae), mint (Mentha haplocalyx Labiatae), coriander (Coriandrum sativum Umbelliferae) leaves can accumulate 5 kinds of heavy metals, have been not suitable for planting in the contaminated area. At the same time, can choose 3 different types of edible parts of vegetables were the highest concentration of heavy metal speciation analysis of heavy metals The results show that the As, mainly in the ethanol extractable and residual state, Pb mainly exists in the state of sodium chloride and Cd residue, mainly acetic acid state and residual state, the main form of Cu and Zn respectively. The state of sodium chloride and acetic acid extraction, description of 5 kinds of heavy metals in As toxicity of most high. In addition, the comprehensive pollution index of 5 kinds of heavy metals in vegetables is Pb As Cd Zn Cu. although soil Cd as high as 39.12%, but in vegetables Cd but with acetic acid extractable and residual activity is relatively low. The residents eating vegetables daily intake of Cd is the provisional tolerable daily intake (PTDI) 1.86 times, far lower than that of Pb (5.71 times) and As (5.12 times). In general, compared with Cd, Pb and As of the local people's life and health poses a greater threat. (2) screening of low absorption pot experiment results showed that varieties of vegetables, vegetables with different varieties of plant height and biomass deposit Significant differences in As. For slightly polluted soil, 27 varieties of vegetables in the edible part of the arsenic content did not exceed the maximum allowable concentration of As (As-MPC); to lead, only some varieties of edible parts of the Pb content is lower than Pb-MPC, and all varieties of edible parts of Cd were more than Cd-MPC. which shows the pot the experiment of soil Pb and Cd pollution is serious, especially the Cd. screening results showed that for the As-Pb-Cd contaminated soil, green show 848 spinach (S3), (P4), vegetable powder rod spring 3, lettuce (A11) and Ma Long Eggplant (A1) compared with the same kind of vegetable, its ability to absorb the heavy metal is more weak, belongs to the relative safety of the varieties of the same vegetable varieties. The contents of heavy metals in the edible parts of obvious morphological analysis results show that: for As, low absorption of spinach leaves (S6) in the form of low activity in Lettuce Cultivars; whether arsenic absorption There are in the low level of activity in the form of low absorption is obvious. The varieties of A15 Pb and Cd, the high absorption of spinach cultivars (S3) leaves at low activity form, low absorption of spinach cultivars (S6) leaves are with high activity and low absorption of eggplant A4 form; Pb exists in low activity form. Therefore, in the low absorption of heavy metal should be taken to avoid metal speciation in the presence of high biological activity. The screening of varieties (3) add modifying agent can change the bioavailability of heavy metals in contaminated soils. In this experiment, orthogonal treatment can significantly reduce most heavy metal bioavailability in soil, the treatment of 7,9 and 10 can significantly reduce the soil available As, 7,9,10,13 and 14 can significantly reduce the soil available Pb, 9,10,11 and 13 can significantly reduce the soil available Cd. In addition, it is worth noting that 9 and 10 can significantly reduce the soil in 3 The effective state of heavy metals, which indicates that the moderate concentration of lime (5g kg-1), low concentration of organic fertilizer (0-25 g kg-1) and high concentration of fly ash (10-15 g kg-1) can effectively improve the As-Pb-Cd contaminated soil. Compared with the control, treatment 9 and 10 soil and vegetables edible part of the content of As decreased significantly, 10 and 13 of soil available vegetables and edible parts of Cd levels were significantly reduced. In addition, additives can promote the growth of vegetables, plant height and biomass, which promote the most significant is the No. 16 treatment. Most improved treatment can improve the quality of Chinese cabbage, in the soluble protein. Soluble sugar, free amino acid and vitamin C content can be maintained or increased. Finally, the result of the speciation analysis of heavy metals in vegetables showed that in leaf and stem, arsenic mainly exists in the form of Fethanol+Fwater, Cd mainly FNaCl+ FHAc form.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X173

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