【摘要】：近年來,我國受重金屬污染的耕地面積持續(xù)增長,由土壤污染導致的食品安全事件頻頻發(fā)生。稻田作為我國第一大糧食作物的耕種地,其重金屬污染帶來的健康風險更為突出。重金屬不僅影響水稻產(chǎn)量和品質(zhì)及整個農(nóng)田生態(tài)系統(tǒng),還可通過食物鏈危及動物和人類的健康。當下,稻田重金屬污染問題日趨凸顯,其污染狀況調(diào)查和防控也愈加緊迫。本文以江安縣境內(nèi)土壤—水稻系統(tǒng)中常見且與人類密切相關的8種重金屬元素(砷、鎘、鉻、銅、汞、鎳、鉛、鋅)為研究對象,對不同方位、不同類型的表層土壤及對應區(qū)稻米中重金屬元素進行了檢測,并參照相關背景值和國家標準評價土壤環(huán)境質(zhì)量、稻米安全質(zhì)量及重金屬污染程度;同時,討論了土壤和稻米中重金屬全量間的相關性以及土壤pH、有機質(zhì)對稻米吸收土壤重金屬能力的影響;并以此為依據(jù),提出了針對性的重金屬污染防控建議。論文研究結果可為江安縣土壤-水稻系統(tǒng)中重金屬污染的防控提供科學依據(jù)。主要研究結果如下:1.以國家土壤二級標準值為參照,該地區(qū)鎘污染最嚴重,受污染比例高達77.1%,根據(jù)內(nèi)梅羅綜合污染指數(shù)評價結果,約三分之一樣點存在生態(tài)安全隱患。以背景值為參照,江安縣重金屬潛在生態(tài)風險指數(shù)較低,為134.59,處無風險狀態(tài)。單項風險系數(shù)大小為:汞鎘砷鉛銅鎳鉻鋅,潛在生態(tài)風險指數(shù)在空間上分布規(guī)律為:北部中部南部,交通干道區(qū)農(nóng)業(yè)耕種區(qū)工業(yè)集中區(qū)自然保護區(qū),平地河漫灘丘陵。2.稻米重金屬中,該地區(qū)鋅含量最高,汞含量最低。以食品安全國家標準為參照,除鎘、鉻個別樣點超標外,其余均達標。根據(jù)內(nèi)梅羅綜合污染指數(shù)評價結果,受污染的稻米比例為8.6%。以背景值為參照,稻米重金屬污染嚴重,鎳污染指數(shù)為23.09,鉛無污染,其他6元素污染指數(shù)介于二者之間�？臻g上的分布規(guī)律為,工業(yè)集中區(qū)所在的中部污染最重,自然保護區(qū)所在的南部污染次之。3.該地區(qū)土壤—水稻系統(tǒng)的重金屬相關性很小,其中砷相關系數(shù)最高,為0.202。水稻對土壤中重金屬的富集系數(shù)介于0.002～0.231之間,順序為:鋅汞鎳鎘銅砷鉻鉛。多元回歸結果表明,富集系數(shù)與土壤pH呈負相關、與土壤有機質(zhì)總體上呈正相關關系。稻米吸收土壤中重金屬的能力受土壤pH的影響程度具體順序為:鎳砷鋅鎘汞銅鉻鉛。
[Abstract]:In recent years, the area of cultivated land polluted by heavy metals has been increasing, and food safety events caused by soil pollution have occurred frequently. As the largest cultivated land of grain crops in China, the heavy metal pollution brings more serious health risks. Heavy metals not only affect the yield and quality of rice and the whole farmland ecosystem, but also endanger the health of animals and human beings through the food chain. At present, the problem of heavy metal pollution in paddy field is becoming more and more serious, and its pollution investigation and prevention and control become more and more urgent. In this paper, eight heavy metal elements (arsenic, cadmium, chromium, copper, mercury, nickel, lead, zinc) which are common in the soil-rice system in Jiangan County are studied. Heavy metal elements in different types of topsoil and rice were detected, and soil environmental quality, rice safety quality and heavy metal pollution were evaluated according to relevant background values and national standards. The correlation between the total amount of heavy metals in soil and rice and the effect of soil pH, organic matter on the ability of rice to absorb heavy metals were discussed, and based on this, some suggestions for prevention and control of heavy metal pollution were put forward. The results can provide scientific basis for the prevention and control of heavy metal pollution in the soil-rice system in Jiangan County. The main results are as follows: 1. According to the national soil secondary standard value, cadmium pollution is the most serious in this area, and the polluted ratio is as high as 77.1. According to the evaluation results of Nemero comprehensive pollution index, there is a hidden danger of ecological security at about one third of the same point. Taking the background value as reference, the potential ecological risk index of heavy metals in Jiangan County was low, 134.59, and it was in a risk-free state. The single risk coefficient is mercury, cadmium, arsenic, lead, copper, nickel, chromium and zinc. The spatial distribution of potential ecological risk index is as follows: the central and southern part of north, the nature reserve of industrial concentration area in agricultural cultivation area of traffic trunk area, and the flat floodplain hilly area. 2. Among the heavy metals in rice, zinc content was the highest and mercury content was the lowest in this area. With food safety national standards as reference, except cadmium and chromium other points exceed the standard, the rest are up to standard. According to the comprehensive pollution index of Nemero, the proportion of contaminated rice was 8.6%. Compared with the background value, the heavy metal pollution of rice was serious, the pollution index of nickel was 23.09, the pollution index of the other six elements was between them. The spatial distribution law is that the pollution in the middle of the industrial concentration area is the most serious, followed by the southern pollution in the nature reserve. 3. 3. The correlation of heavy metals in the soil-rice system is very small, and the correlation coefficient of arsenic is the highest (0.202). The enrichment coefficient of heavy metals in soil by rice was between 0.002 and 0.231, in the order of zinc, mercury, nickel, cadmium, copper, arsenic, chromium and lead. The results of multiple regression showed that the enrichment coefficient was negatively correlated with soil pH and positively correlated with soil organic matter in general. The order of the ability of rice to absorb heavy metals in soil affected by soil pH was: nickel, arsenic, zinc, cadmium, mercury, copper, chromium, lead.
【學位授予單位】：南京農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X825;S511

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