土壤镉污染对不同品种水稻的毒性阈值及其物种敏感性分布

发布时间：2018-05-09 07:22

本文选题：富集系数 + 转运系数　；参考：《中国农业科学院》2015年硕士论文

【摘要】：土壤镉(Cd)污染对水稻的环境风险已受到了广泛的关注,但我国还缺乏切实可行的稻田Cd风险评价体系,且针对不同性质土壤的Cd风险阈值研究还相对薄弱。因此,本研究依据我国地域土壤性质(土壤p H、有机碳等)差异,选取我国8个不同地区的典型农田表层(0-20 cm)土壤,同时选取了我国水稻主产区的3种对Cd敏感性不同的水稻品种为试材,结合Log-logistic模型拟合得到水稻Cd毒性与土壤中Cd浓度的剂量-效应关系,进而获得土壤Cd污染对水稻的毒性阈值(EC10、EC50)。并通过逐步回归分析,确定水稻Cd毒性与土壤性质间的相互关系,探明水稻Cd毒性的土壤主控因子,并建立了水稻Cd毒性与土壤主控因子的毒性阈值预测模型。同时选取20种不同品种水稻开展了基于籽粒Cd含量的水稻Cd吸收敏感性研究,并通过BurrIII分布函数拟合获得了土壤中Cd对水稻毒性的物种敏感性分布(SSD),依据国家食品卫生稻米Cd限量标准推导出土壤中Cd浓度的阈值,为我国稻田土壤Cd污染防控及土壤Cd污染限量标准的修订提供参考。主要研究结果如下:1.不同性质土壤对Cd的水稻毒性有显著影响,Cd敏感性水稻品种T优167的毒性阈值EC10变化为1.40-5.25 mg·kg-1,EC50变化为17.83-46.93 mg·kg-1;Cd非敏感性品种湘早45的毒性阈值EC10变化为1.72-8.22 mg·kg-1,EC50变化为26.96-68.16 mg·kg-1。通过水稻Cd毒性阈值ECx与土壤性质间的多元回归分析证实了土壤p H、有机碳含量(OC)、阳离子交换量(CEC)是控制水稻Cd毒性的主控因子。其水稻Cd毒性预测模型为:Log(EC50)=0.078 pH+0.208 log(CEC)+0.202 log(OC)+0.705(R2=0.94,n=24),且pH、OC、CEC可以控制Cd毒性预测模型94.1%的变异性。2.在Cd浓度4.8 mg·kg-1以下的土壤上种植水稻不会显著降低水稻籽粒的产量,其籽粒产量的变化为20.69-37.22 g·pot-1。相同品种水稻在不同Cd浓度处理下,其根、茎叶、籽粒中Cd浓度逐渐增加,而相同Cd浓度处理下,不同品种水稻的根、茎叶、籽粒中Cd浓度存在显著的差异,在不同Cd浓度处理下Cd浓度相差1.52-4.11倍;1.68-3.52倍;3.54-6.00倍。Cd由根迁移转运至茎叶的转运系数TFstraw在不同品种间存在显著的差异,不同品种间TFstraw的变异系数为:41.02%-71.18%。而Cd由茎叶迁移转运至籽粒的转运系数TFgrain不同品种间差异不显著,其变异系数为:10.82%-27.50%。故转运系数TFstraw比TFgrain更能真实准确的反映不同品种水稻对Cd的吸收转运能力的差异,且不同品种水稻籽粒Cd积累量的差异主要是由于Cd由根迁移转运至茎叶的能力不同引起的。3.不同品种水稻对Cd的富集系数(BCF)存在显著差异,其变化为0.28-1.54。BCF在不同Cd浓度处理中的变异系数为10.79%-27.72%。水稻籽粒Cd浓度高的品种具有较高的转运系数和富集系数,反之,具有较低的转运系数和富集系数。故BCF可以较好的反映出不同品种水稻对Cd敏感性的差异。通过BurrIII分布函数可以很好的拟合1/BCF的物种敏感度分布,拟合函数的R2达0.9977。基于水稻籽粒Cd浓度,以国家食品卫生稻米Cd限量标准(0.2mg·kg-1)为基准,反推出土壤中Cd的限量上限浓度值为0.57 mg·kg-1,从而可以确保95%的水稻籽粒Cd浓度符合标准。
[Abstract]:Soil cadmium (Cd) pollution has been widely concerned about the environmental risk of rice, but there is still a lack of practical Cd risk assessment system in our country, and the research on the Cd risk threshold for different soils is relatively weak. Therefore, this study is based on the differences of the regional soil properties of China (soil P H, organic carbon, etc.), and selects 8 different areas of our country. The typical farmland (0-20 cm) soil in the region, and 3 varieties of rice varieties with different sensitivity to Cd in the main rice producing area of our country were selected, and the dose effect relationship between the Cd toxicity of rice and the concentration of Cd in the soil was fitted with the Log-logistic model, and the toxicity threshold (EC10, EC50) of soil Cd contamination (EC10, EC50) was obtained. Regression analysis was used to determine the relationship between Cd toxicity and soil properties, to explore the main control factors of soil Cd toxicity and to establish a model for predicting the toxicity threshold of rice Cd toxicity and soil principal control factors. At the same time, 20 different varieties of rice were selected to carry out the study on the Cd absorption sensitivity of rice based on the Cd content of grain and through BurrIII. The distribution function fitting obtained the species sensitivity distribution of Cd to rice in the soil (SSD). According to the national food hygienic rice Cd limit standard, the threshold of Cd concentration in soil was derived, which provided a reference for the prevention and control of Cd pollution in paddy soil and the revision of the standard of soil Cd pollution limit. The main results are as follows: 1. different properties of soil to Cd The toxic threshold of Cd sensitive rice variety T you 167 changed to 1.40-5.25 mg. Kg-1, EC50 changed to 17.83-46.93 mg kg-1, and the toxicity threshold of Xiang Zao 45, which was not sensitive, was changed to 17.83-46.93. Multivariate regression analysis confirmed that soil P H, organic carbon content (OC) and cation exchange amount (CEC) are the main controlling factors for controlling Cd toxicity of rice. The Cd toxicity prediction model of rice is Log (EC50) =0.078 pH+0.208 log (CEC). The yield of rice grain was not significantly reduced by planting rice under.8 mg / kg-1. The variation of grain yield was 20.69-37.22 G. Pot-1.. The concentration of Cd in root, stem, leaf and grain increased gradually under the treatment of different Cd concentrations. The concentration of Cd in the roots, stems, leaves and grains of different varieties of rice was stored under the same Cd concentration treatment. In the significant difference, the difference of Cd concentration was 1.52-4.11 times of different Cd concentration and 1.68-3.52 times, and the transport coefficient TFstraw of 3.54-6.00 times.Cd from root migration to stem and leaf was significant difference among different varieties. The variation coefficient of TFstraw in different varieties was 41.02%-71.18%. while Cd was transported from stem and leaf to grain, and the transport coefficient TFgra was TFgra. The variation coefficient of in is not significant, and its coefficient of variation is 10.82%-27.50%. so that the transfer coefficient TFstraw is more true and accurate than TFgrain to reflect the difference in the absorption and transport capacity of different varieties of rice to Cd, and the difference in the accumulation of Cd in the grain of different varieties of rice is mainly caused by the.3. of Cd from the transfer of root migration to the stem and leaf. The enrichment coefficient (BCF) of different varieties of rice (Cd) has significant difference. The variation is that the variation coefficient of 0.28-1.54.BCF in different Cd concentrations is higher in 10.79%-27.72%. rice grain with higher Cd concentration and higher in transport coefficient and enrichment factor. On the contrary, it has a lower transfer coefficient and enrichment factor. Therefore, BCF can be better reflected. The difference in sensitivity of different varieties of rice to Cd was found. Through the BurrIII distribution function, the species sensitivity distribution of 1/BCF could be well fitted. The R2 of the fitting function was based on the Cd concentration of rice grain, based on the national food hygienic rice Cd limit standard (0.2mg. Kg-1), and the limit limit concentration of Cd in the soil was 0.57 mg. This can ensure that 95% of the Cd concentration of rice seeds meets the standards.

【学位授予单位】：中国农业科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

【参考文献】