不同秸秆利用农业循环模式下重金属Pb、Cr、Cd、As的分配特征及其评价

发布时间：2018-02-27 03:21

本文关键词： 农业循环秸秆重金属分配污染风险评价　出处：《河南师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：在我国的农业生产中,每年都有数量庞大的秸秆资源不能被有效利用,循环农业的发展可以有效的实现秸秆的资源化,将其变废为宝。农田循环、农菌循环和农牧循环是河南省的三种常见的农业循环模式。但是在这些循环模式中不仅仅存在营养元素的迁移传递,重金属等有害元素也随之而发生迁移,从而胁迫农作物的生长造成粮食减产,并通过食物链进入人体直接危害人类健康。本研究以农田循环、农菌循环和农牧循环三种循环模式为载体,针对2013-2014年小麦和玉米两季作物秸秆,采用秸秆直接粉碎还田、秸秆栽培食用菌后还田、秸秆过腹还田等形式,采集相应农作物的土壤、秸秆、籽粒,食用菌的菌料、食用菌体、菌渣,以及畜牛的饲料、牛肉、牛粪样品,利用电感耦合等离子发射光谱法(ICP)测定样品中重金属Pb、Cr、Cd、As含量,以摸清重金属在三种农业循环链中的分配特征,并通过单项污染指数法和内梅罗综合污染指数法来评价重金属的污染风险,通过不同循环模式间富集系数和重金属转运率的对比对,不同循环链中重金属控制措施进行深入探讨。通过对研究的分析与讨论,得到主要结论如下:1.在小麦-玉米两熟农田秸秆直接还田的农田循环模式中,四种重金属在土壤中的含量没有超过《土壤环境质量标准》(GB15618-1995)中的规定,其中重金属Cr和Cd在小麦和玉米的根系中含量比土壤有明显上升,表现出来一定程度的富集;Pb和As则没有这个现象;重金属从农作物的根系到茎叶再到籽粒,其含量依次降低,但是在小麦籽粒和玉米籽粒中Pb和As的污染风险较高;在一个循环周期后,农田土壤中四种重金属的含量Cr为持平,Pb、Cd和As有小幅下降。2.在利用作物秸秆栽培食用菌,并将菌渣再还田的农菌循环模式中,重金属在食用菌菌料中的含量和相应农作物秸秆中的含量相近,而食用菌中重金属含量较低,其大部分残留在菌渣中;菌渣还田后,土壤中四种重金属的含量都处于《土壤环境质量标准》(GB15618-1995)限量标准以下,农作物的根系对Pb和As没有明显的富集,而重金属Cr和Cd的含量较土壤则出现了大幅升高;同时籽粒中的重金属含量低于茎叶,其中只有玉米籽粒中的Pb具有轻度污染风险。3.在利用作物秸秆饲喂畜牛,牛粪再还田的农牧循环中,饲料中的重金属含量略高于对应秸秆中的含量,牛粪中的重金属含量基本上和饲料中的持平;小麦季和玉米季秸秆饲喂畜牛的牛肉的重金属含量都远低于我国食品卫生标准《食品中污染物限量》(GB2762-2005)中的规定;牛粪还田后,重金属Pb、Cr、Cd和As在土壤中的含量低于《土壤环境质量标准》(GB15618-1995)限量标准值,在农作物体内重金属含量均为根系茎叶籽粒,对籽粒的重金属污染风险评价均为未污染。4.经单项污染指数法和内梅罗综合污染指数法对三种秸秆利用循环模式中不同环节重金属污染状况评价显示,在土壤重金属没有超标的情况下,小麦和玉米籽粒易受重金属Pb和As的污染;对此三种循环模式,农菌循环中从秸秆向食用菌迁移的重金属量要高于农牧循环中从秸秆向牛肉中的迁移,所以农菌循环中食用菌更容易受到重金属污染;三种农业循环模式中重金属浓度富集系数最高的部位是农作物的根系,重金属转运率最高的是农作物的茎叶,因此根、茎叶应该是农业循环中重金属迁移阻控的关键节点。
[Abstract]:In the agricultural production in China, there are a large number of straw resources can not be effectively used by each year, the development of circular agriculture of straw resources can be achieved effectively, will waste into treasure. Farmland circulation, circulation and circulation of agriculture and animal husbandry agricultural bacteria are three common agricultural circulation pattern in Henan Province. But the migration not only exist nutrient elements in these cycles in the mode of transmission, heavy metals and other harmful elements also migrate to stress the growth of crops, resulting in food production, and enter the body through the food chain directly harmful to human health. The study on farmland circulation, agricultural and pastoral cycle cycle bacteria three cycle mode as the carrier, for 2013-2014 years of wheat and corn two crops straw, the straw crushing returning straw mushroom cultivation after returning straw, manure fertilizer and other forms of collecting the corresponding crop soil, straw, seeds Grain, edible mushroom, edible fungus bacteria, bacteria residue, and feed cattle, beef cattle manure samples by inductively coupled plasma atomic emission spectrometry (ICP) determination of heavy metals Pb, Cd, Cr in the sample, the content of As, in order to find out the three kinds of heavy metals in the agricultural cycle in the chain of distribution, pollution risk and through the single pollution index and comprehensive pollution index method to evaluate the Nemero heavy metals, through different circulation patterns between the enrichment coefficient and translocation rate of heavy metals, heavy metals in different cycle chain control measures are discussed. Through the analysis and discussion of the research, the main conclusions are as follows: 1. in wheat corn two crops straw directly returning farmland circulation mode, the content of four kinds of heavy metals in soil did not exceed the "soil environmental quality standard" (GB15618-1995) provisions in which heavy metals Cr and Cd in wheat and maize roots The content is significantly higher than that in the soil, showing a certain degree of enrichment; Pb and As do not have this phenomenon; heavy metals from crop roots to stems and leaves to grain, its content decreased, but the pollution risk is higher in wheat grain and corn grain in Pb and As; in a cycle, the content of Cr four kinds of heavy metals in farmland soil is flat, Pb, Cd and As slightly decreased.2. in the utilization of crop straw mushroom cultivation, and the agricultural circulation pattern of mushroom residue returning to bacteria in the similar content of heavy metals in the edible fungus material content and the corresponding crop stalks, and the content of heavy metals in edible fungi the low, most of its residues in mushroom residue; mushroom residue returned to the field, the content of four kinds of heavy metals in soil are in the "soil environmental quality standard" (GB15618-1995) standard, the enrichment of Pb and root crops without As significantly, and heavily The content of Cr and Cd than the soil sharply increased; at the same time, the heavy metal content in grains was lower than that of stems and leaves, which only maize Pb with mild pollution risk of.3. in the utilization of crop straw feeding cattle, cattle manure and straw farming cycle, heavy metal content in feed is slightly higher than the corresponding content in straw the flat, heavy metal content in cow dung basically and feed in the heavy metal content of beef; wheat and maize straw feeding livestock cattle are far lower than the limit of food hygiene standard < > pollutants in food in China (GB2762-2005) in cow dung after returning, provisions; heavy metals of Pb, Cr content in soil Cd and As are lower than that of "soil environmental quality standard" (GB15618-1995) standard limit value in the heavy metal content in crops are the root stem leaf grain, risk assessment of heavy metals pollution in grain were not polluted by.4. single pollution With Nemero index method and comprehensive pollution index method to evaluate three kinds of heavy metals pollution status of different aspects of circulation patterns in the utilization of straw, soil heavy metals did not exceed the standard in the case of wheat and maize grain is vulnerable to heavy metal Pb and As pollution; these three kinds of circulation patterns, migration from straw to edible agricultural heavy metal bacteria cycle is higher than that of migration from straw to beef in the agricultural cycle, so agricultural circulation of edible fungi bacteria more susceptible to heavy metal pollution; three kinds of heavy metals in agricultural circulation patterns in the concentration enrichment coefficients were the highest agricultural crop root system, heavy metal transport rates are highest in stems and leaves, so the crop root, stem and leaf should be the key nodes control the migration of heavy metals in agricultural circular.

【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X712;S38

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