【摘要】：汞是一種全球關(guān)注的高毒性金屬元素,汞礦區(qū)一直是汞污染研究的熱點區(qū)域之一。研究表明,位于貴州省東部的萬山汞礦區(qū)的水稻可以富集甲基汞,食用大米是當(dāng)?shù)鼐用窦谆┞兜闹饕緩�。同時,硒作為萬山汞礦的伴生元素可能會影響汞的生物地球化學(xué)循環(huán)。因此,非常有必要對稻田生態(tài)系統(tǒng)硒對甲基汞遷移轉(zhuǎn)化的影響進行研究。本研究通過野外調(diào)查實驗和室內(nèi)模擬實驗兩方面開展。系統(tǒng)采集萬山汞礦區(qū)的稻米樣品,測定其總汞、甲基汞以及總硒含量,分析稻米汞、硒之間的相互關(guān)系,探討硒對稻米中總汞和甲基汞生物富集的影響。此外,通過室內(nèi)模擬實驗,水培種植水稻幼苗,進行硒添加背景下的水稻幼苗對甲基汞的吸收動力學(xué)實驗,以探究硒對水稻甲基汞吸收和遷移轉(zhuǎn)化的影響,為汞污染地區(qū)的生物修復(fù)提供新的途徑和啟示。1)貴州萬山汞礦區(qū)稻米總汞含量幾何平均值為24.0 ng·g-1(2.40~401 ng·g-1),51%的樣品超過我國食品汞限量標(biāo)準(zhǔn)(20 ng·g-1);甲基汞含量幾何平均值為8.97ng·g-1(1.10~45.1 ng·g-1),占總汞平均比例的44.8±23.9%。稻米總汞含量分布表現(xiàn)為上游尾礦堆附近區(qū)域汞污染嚴(yán)重,隨流域往下汞含量顯著降低,這表明汞礦活動是當(dāng)?shù)氐久讎?yán)重汞污染的原因。萬山汞礦區(qū)稻米硒含量幾何平均值為124.3 ng·g-1(21.45~1991 ng·g-1),顯著高于我國糧食硒的平均含量(40~70ng·g-1),這與當(dāng)?shù)赝寥栏呶坑嘘P(guān)。2)萬山汞礦區(qū)稻米硒含量與總汞含量無顯著相關(guān)性。當(dāng)?shù)久孜凹谆烤^低時,硒與甲基汞之間無明顯相關(guān)性;當(dāng)硒或甲基汞含量較高時,兩者呈現(xiàn)出明顯的反相關(guān)關(guān)系,這表明硒可以顯著抑制水稻對甲基汞的吸收和富集。3)室內(nèi)模擬實驗表明,水稻生長期間,硒對水稻幼苗甲基汞的含量有顯著影響。一定濃度范圍內(nèi)Se(VI)能有效抑制水稻甲基汞的吸收,且不同濃度Se(VI)其抑制作用存在差異。而同一濃度的Se(IV)則能促進水稻對甲基汞的吸收。4)水稻根系對甲基汞富集能力較強,但向地上部分運轉(zhuǎn)則相對困難。硒的添加對甲基汞在水稻根部和莖葉的分配具有顯著影響(P0.05)。水稻根系對甲基汞的吸收系數(shù)隨水稻生長而增大,變化范圍為2.54~122;而水稻轉(zhuǎn)運系數(shù)則隨水稻生長呈下降趨勢,變化范圍為0.22~0.74。Se(VI)處理在某一閾值內(nèi)能降低水稻根系對甲基汞的富集以及根部向莖葉轉(zhuǎn)運甲基汞的能力,而Se(IV)處理則會促進水稻根部對MeHg的吸收。5)水稻至成熟時稻米甲基汞含量的估算表明,Se(VI)對稻米甲基汞的富集表現(xiàn)為抑制作用,而Se(IV)則可能會促進稻米中甲基汞的富集。
[Abstract]:Mercury is a highly toxic metal element of global concern. Mercury mining area has always been one of the hot areas of mercury pollution research. The study shows that rice can enrich methyl mercury in the Wanshan mercury mine area in the eastern part of Guizhou province. Therefore, it is very necessary to study the effect of selenium on the migration and transformation of methyl mercury in rice field ecosystem. This study is carried out through two aspects of field investigation and indoor simulation experiments. The rice samples of the Wanshan mercury mining area are collected systematically to determine the total mercury, methyl mercury and total selenium content, and the analysis of rice rice The relationship between mercury and selenium, and the effects of selenium on the bioaccumulation of total and methyl mercury in rice. In addition, the experiment on the absorption and transformation of methyl mercury from rice seedlings in Rice Seedlings under the background of selenium supplementation was carried out to explore the effects of selenium on the absorption and transfer of methyl mercury in rice. The bioremediation of the area provides a new way and inspiration.1) the geometric mean value of the total mercury content in the Guizhou Wanshan mercury mining area is 24 ng. G-1 (2.40~401 ng. G-1), and 51% of the samples exceed our national food mercury limit standard (20 ng. G-1); the geometric mean of the methyl mercury content is 8.97ng g-1 (1.10~45.1 ng.), accounting for the average percentage of total mercury 44.8 +. The distribution of the total mercury content of the rice was serious in the vicinity of the upstream tailings heap, and the mercury content decreased significantly with the lower mercury content in the basin. This indicates that the mercury mine activity is the cause of serious mercury pollution in the local rice. The geometric mean value of the rice selenium content in the Wanshan mercury mine is 124.3 ng. G-1 (21.45~1991 ng. G-1), which is significantly higher than the average content of the grain selenium in China (40~ 70ng. G-1) there was no significant correlation between the content of rice selenium and total mercury content in the Wanshan mercury mining area. There was no significant correlation between the content of selenium and the total mercury content in the Wanshan mercury mining area. There was no significant correlation between selenium and methyl mercury when the content of rice selenium and methyl mercury was low. When the content of selenium or methyl mercury was high, the two showed a clear anti correlation relationship, which indicated that selenium could be significantly inhibited. Indoor simulation experiments on the absorption and enrichment of methyl mercury in rice showed that the content of methyl mercury in rice seedlings was significantly affected by selenium during the growth period of rice. Se (VI) could effectively inhibit the absorption of methyl mercury in rice, and the different concentrations of Se (VI) were different in a certain concentration range, while the same concentration of Se (IV) could promote rice treatment. The absorption of methyl mercury by.4) the ability of rice roots to enrich methyl mercury is stronger, but it is relatively difficult to run to the upper part of the earth. The addition of selenium to the distribution of methyl mercury in the roots and stems of rice has significant influence (P0.05). The absorption coefficient of methyl mercury in rice root increases with the growth of rice, and the range of variation is 2.54~122. As the growth of rice decreased, the range of variation was 0.22~0.74.Se (VI) treatment in a certain threshold to reduce the enrichment of rice roots to methyl mercury and the ability to transport methyl mercury to the stems and leaves, while Se (IV) treatment would promote the absorption of MeHg by the rice root to MeHg. The estimation of the content of methyl mercury in rice from rice to maturity showed that Se (VI) was to rice. The enrichment of M methyl mercury is inhibited, while Se (IV) may promote the enrichment of methylmercury in rice.
【學(xué)位授予單位】：貴州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S511;X56

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