【摘要】：土壤是人類賴以生存的基礎(chǔ),Cd是一種劇毒的重金屬元素,其通過食物鏈途徑可以累積于人體內(nèi)。稻米是人類主要的糧食作物,人體攝入Cd主要通過稻米。因此通過吸收系數(shù)研究土壤鎘污染與稻米鎘富集的關(guān)聯(lián)性,并以此為依據(jù)篩選稻米Cd風(fēng)險(xiǎn)種植區(qū),可以避免鎘米對(duì)人體產(chǎn)生危害。為滿足數(shù)據(jù)保密性需要和提高使用便捷性,建立了研究用數(shù)據(jù)庫。以市、縣、鎮(zhèn)不同尺度探討了區(qū)域吸收系數(shù)的差異性,并研究了造成差異性的原因,探討了四種有效態(tài)方法對(duì)稻米Cd的預(yù)測(cè)能力,并基于上述研究結(jié)果篩選了稻米鎘風(fēng)險(xiǎn)種植區(qū)。主要研究結(jié)論如下:(1)對(duì)不同區(qū)域吸收系數(shù)差異性進(jìn)行了描述性統(tǒng)計(jì),結(jié)果表明:市、縣、鎮(zhèn)都為中高度變異。不同區(qū)域吸收系數(shù)差異性的方差分析表明,研究所選用的不同市、不同縣吸收系數(shù)存在普遍的顯著差異,而在同一縣的不同鎮(zhèn)之間幾乎不存在顯著性差異,因此選取縣為尺度來確定區(qū)域吸收系數(shù)。(2)吸收系數(shù)差異性的最主要影響因素為pH值,整體上呈現(xiàn)隨著pH值升高吸收系數(shù)下降的趨勢(shì)。當(dāng)細(xì)化pH間隔到0.1時(shí),吸收系數(shù)在4.8~6.0區(qū)間幾乎沒變化,但當(dāng)pH為6.0~6.3時(shí)出現(xiàn)吸收系數(shù)下降突變點(diǎn)。當(dāng)土壤pH為小于6.0時(shí),吸收系數(shù)最高,且變化平緩;當(dāng)土壤pH大于下降突變點(diǎn)時(shí),吸收系數(shù)急劇下降;當(dāng)土壤pH大于7.0時(shí)吸收系數(shù)降到最低。(3)土壤有機(jī)質(zhì)、土壤質(zhì)地、土壤類型也會(huì)對(duì)吸收系數(shù)產(chǎn)生影響,但影響性遠(yuǎn)小于土壤pH值。不同土壤污染程度下吸收系數(shù)隨污染程度升高而降低。土壤Zn/Cd也會(huì)影響吸收系數(shù),吸收系數(shù)較大的地區(qū)土壤Zn/Cd比較小,且土壤Zn/Cd比大于稻米Zn/Cd比,可能原因是Zn抑制稻米對(duì)Cd的吸收和Cd在稻米中的遷移轉(zhuǎn)化。(4)有效態(tài)測(cè)定DGT方法、CaCl2方法都可以作為預(yù)測(cè)稻米Cd的有效方法。當(dāng)土壤Cd有效率很低時(shí),稻米Cd的吸收系數(shù)顯著低于其它有效率時(shí)的吸收系數(shù)。當(dāng)有效率高于某一值后,不同有效率下稻米Cd的吸收系數(shù)無顯著差異。當(dāng)pH值降低時(shí),土壤Cd有效率有升高的趨勢(shì);土壤pH大于7.0時(shí),土壤Cd有效率降至最低。(5)本研究對(duì)湖南、廣東、浙江進(jìn)行了稻米Cd風(fēng)險(xiǎn)種植區(qū)篩選。結(jié)果表明,湖南地區(qū)稻米種植區(qū)Cd風(fēng)險(xiǎn)程度高于廣東,廣東又高于浙江。浙江的稻米種植區(qū)Cd風(fēng)險(xiǎn)幾乎都為安全級(jí)別。
[Abstract]:Soil is the basis of human survival. Cd is a highly toxic heavy metal element, which can be accumulated in human body through the food chain. Rice is the main food crop for human beings. Human body ingest Cd mainly through rice. Therefore, by studying the correlation between cadmium pollution in soil and cadmium enrichment in rice by absorption coefficient, and selecting rice Cd risk planting area based on this, the harm of cadmium rice to human body can be avoided. In order to meet the need of data confidentiality and improve the convenience of use, a research database was established. In this paper, the difference of regional absorption coefficient was discussed at different scales of city, county and town, and the cause of the difference was studied. The prediction ability of four effective state methods for rice Cd was discussed. Based on the above results, rice cadmium risk growing areas were selected. The main conclusions are as follows: (1) the difference of absorption coefficient in different regions is described. The results show that: city, county and town are medium height variation. The variance analysis of the difference of absorption coefficient in different regions shows that there are significant differences in absorption coefficient between different cities and different counties, but there is almost no significant difference among different towns in the same county. Therefore, the county is chosen as the scale to determine the regional absorption coefficient. (2) the main influencing factor of the difference of absorption coefficient is the pH value, and the overall absorption coefficient decreases with the increase of the pH value. When the pH interval is refined to 0.1, the absorption coefficient almost does not change in the range of 4.86.0.However, when the pH is between 6.0 and 6.3, the abrupt point of absorption coefficient decreases. When the soil pH is less than 6.0, the absorption coefficient is the highest and the change is gentle, and when the soil pH is larger than the decreasing mutation point, the absorption coefficient decreases sharply. (3) soil organic matter, soil texture and soil type also affect the absorption coefficient, but the influence is much less than the soil pH value. The absorption coefficient decreased with the increase of soil pollution. Soil Zn/Cd also affected the absorption coefficient. The soil Zn/Cd ratio was smaller and the soil Zn/Cd ratio was higher than the rice Zn/Cd ratio in the areas with higher absorption coefficient. The possible reason is that Zn inhibits the absorption of Cd in rice and the migration and transformation of Cd in rice. (4) DGT method and CaCl2 method can be used to predict Cd in rice. When the soil Cd efficiency was very low, the absorption coefficient of rice Cd was significantly lower than that of other efficient rice. When the effective rate was higher than a certain value, there was no significant difference in the absorption coefficient of rice Cd under different effective rates. When pH value decreased, soil Cd efficiency increased, and soil Cd efficiency decreased to the lowest when soil pH was greater than 7.0. (5) in Hunan, Guangdong and Zhejiang provinces, rice Cd risk planting areas were screened. The results showed that the Cd risk level in rice growing areas in Hunan was higher than that in Guangdong and Zhejiang. The Cd risk in rice growing areas in Zhejiang Province is almost always a safety level.
【學(xué)位授予單位】：中國農(nóng)業(yè)科學(xué)院
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X53

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