区域尺度下农田土壤微生物对重金属和土壤特性的响应与定向变异

发布时间：2018-07-25 12:37

【摘要】：由于城镇化、工业化的快速发展,我国土壤重金属污染已成为近几十年来的重要环境问题。农业土壤重金属污染会造成土壤功能紊乱和作物中重金属的含量增加。水稻是我国第一大粮食作物,稻米的品质与人们的健康息息相关。因此,开展土壤-水稻系统重金属污染的研究,对土壤环境质量监测和保障农产品安全具有重要意义。同时,土壤重金属污染易导致微生物群落结构的变化,进而影响到土壤生态系统的功能多样性和生物化学过程。目前此类研究多为实验室实验或小范围进行的田间实验,因此,有必要进行区域尺度下微生物对重金属和土壤特性的响应分析,探究农田微生物的关键影响因子,为农业可持续发展和生态环境的保护提供依据。本研究以浙江省温岭市为研究区域,利用地统计和多元统计分析方法,系统研究了土壤-水稻系统重金属污染现状、趋势、潜在生态风险和人体健康风险；分析了土壤微生物群落结构的空间分布特征及其与重金属和土壤特性的响应关系。获得的主要结果如下：(1)通过地统计和空间分析方法,对土壤-水稻系统重金属的时空变异研究表明,空间上,研究区土壤和水稻重金属均有一定的空间分布规律；时间上,与2006年相比,土壤中Cd、Cu和Pb的平均含量增加。土壤Cd和Cu含量增加区域最明显。水稻中Cd的平均含量增加了近一倍,并且含量增加区域分布普遍,须引起重视。(2)参照土壤环境质量二级标准,土壤中Cd和Cu的超标率最高。与国家食品卫生标准相比较,水稻中Cd超标率最高,有轻微污染特征。Cd潜在生态风险指数最高,达到了中等危害水平。成人和儿童面临的非致癌风险主要来自食用大米,成人风险高于儿童。研究区居民面临致癌风险,且Cd的致癌风险大于Ni。土壤重金属潜在风险指数,健康风险评价指数均在北部和西南部存在高值区。(3)相关分析和RDA分析表明,Zn和Cu主要与社会环境因子关系密切。Cd和Pb与农业活动相关。Ni主要受土壤理化性状影响。土壤环境因子共解释了43.3%的重金属总变异。(4)土壤微生物单个脂肪酸和各类群磷脂脂肪酸绝对含量均为研究区西南部含量较高。通过因子分析和回归分析表明,单个脂肪酸中,18:1ω9c、i15:0、il6:0、a17:0、 i17:0、cy19:0ω8c、10Me16:0和10Me18：0的关键影响因子为土壤理化性状；16：00、16：1ω5c、16：1ω7c、18：1ω7c、a15：0、cy17：0和18：2ω6,9c与土壤理化性状和重金属密切相关。对于微生物类群,细菌、革兰氏阴性菌、革兰氏阳性菌和真菌受土壤重金属含量和理化性状的综合影响；放线菌则主要受土壤理化性状的影响。土壤环境因子中,有机碳是微生物的主要促进因子。影响微生物的重金属主要为Cd和Cu。Cd表现为抑制作用,Cu对微生物具有明显的促进作用。(5)对微生物磷脂脂肪酸相对含量的分析表明,16:00、16:1ω7c、18:1ω7c、 18:1ω9c、115:0、cy19:0ω8c、10Me16:0为研究区土壤微生物的优势类群,细菌丰度最高,其次为放线菌,真菌最低。地统计分析表明,各特征脂肪酸的相对含量的分布格局差异较大。细菌和革兰氏阴性菌在研究区东部和西北部的相对含量较高；革兰氏阳性菌和放线菌的高值区位于研究区西北部；真菌的高值区主要分布在偏南部地区。革兰氏阳性菌与重金属呈负相关,革兰氏阴性菌和阳性菌的比值与重金属的正相关关系表明重金属污染土壤中,革兰氏阴性菌比革兰氏阳性菌更具优势；真菌与重金属呈负相关关系；真菌和细菌的比值与Cd显著负相关,表明研究区土壤重金属污染导致土壤生态系统稳定性降低；cy/pre与重金属的正相关关系说明重金属污染已对研究区土壤微生物群落结构产生了胁迫作用。RDA分析表明,环境因子共解释微生物群落结构39.8%的变异,其中土壤理化性状解释33.4%的变异,重金属解释的变异量为14.7%。土壤微生物群落结构的主要影响因素为pH、电导率(EC)、有机碳(OC)、重金属、机械组成以及铝氧化物。(6)Shannon指数、Pielou均匀性指数和Simpson优势度指数空间分布规律相似,高值区均存在于研究区西南部。相关分析表明,三种多样性指数与重金属存在显著正相关关系,表明本研究区土壤中重金属污染对微生物存在中等程度的胁迫,导致微生物多样性和均匀度增加,优势度降低。
[Abstract]:Due to urbanization and rapid development of industrialization, heavy metal pollution in soil in China has become an important environmental problem in recent decades. Heavy metal pollution in agricultural soils will cause soil dysfunction and increase the content of heavy metals in crops. Rice is the first major grain crop in China. The quality of rice is closely related to the health of people. Therefore, the quality of rice is closely related to people's health. The study of heavy metal pollution in the spreading soil rice system is of great significance for monitoring soil environmental quality and ensuring the safety of agricultural products. At the same time, heavy metal pollution in soil easily leads to the change of microbial community structure, and then affects the functional diversity and biologic process of soil ecosystem. Or small field experiments, therefore, it is necessary to analyze the response of microbes to the characteristics of heavy metals and soil under regional scale, explore the key influencing factors of agricultural microbes, and provide the basis for the sustainable development of agriculture and the protection of the ecological environment. This study takes Wenling, Zhejiang as the research area, and uses land statistics and multivariate analysis. The statistical analysis method was used to systematically study the current situation, trend, potential ecological risk and human health risk of soil rice system, and analyze the spatial distribution characteristics of soil microbial community structure and its response to the characteristics of heavy metals and soil. The main results are as follows: (1) through the method of land statistics and spatial analysis The spatial and temporal variation of heavy metals in soil rice system showed that the spatial distribution of heavy metals in soil and rice had a certain spatial distribution in the study area. Compared with 2006, the average content of Cd, Cu and Pb in soil increased. The increase of soil Cd and Cu content was most obvious. The average content of Cd in rice increased by nearly one time. More attention should be paid to the increasing regional distribution of the content. (2) according to the two grade standard of soil environmental quality, the highest rate of Cd and Cu in the soil is the highest. Compared with the national food hygiene standard, the rate of Cd exceeding the standard in rice is the highest, and the potential ecological risk index of.Cd has the highest level, which has reached the middle hazard level. The risk of cancer is mainly from edible rice, and the risk of adult is higher than that of children. The risk of carcinogenesis of the residents in the study area is higher than that of the Ni. soil heavy metal potential risk index, and the health risk assessment index is high in the northern and southwestern regions. (3) correlation analysis and RDA analysis show that Zn and Cu are closely related to social environmental factors. The effects of cutting.Cd and Pb on agricultural activities were mainly influenced by soil physical and chemical properties. The total variation of 43.3% heavy metals was explained by soil environmental factors. (4) the absolute content of single fatty acid and phosphatidic fatty acids in soil microorganism was higher in the southwest of the study area. Through factor analysis and regression analysis, the individual fatty acid, 18:1 The key influence factors of Omega 9C, i15:0, il6:0, a17:0, i17:0, cy19:0 Omega 8C, 10Me16:0 and 10Me18:0 are soil physicochemical properties; 16:00,16:1 Omega 5C, 16:1 Omega, Omega, and Omega are closely related to soil physicochemical properties and heavy metals. For microbial groups, bacteria, Gram-negative bacteria, Gram-positive bacteria and true The bacteria were affected by the comprehensive effects of heavy metal content and physicochemical properties of soil, and actinomycetes were mainly influenced by soil physical and chemical properties. Organic carbon was the main promoting factor in soil environmental factors. Heavy metals affecting microbes were mainly inhibited by Cd and Cu.Cd, and Cu had obvious promoting effect on microorganism. (5) microorganism The analysis of the relative content of phosphatidylcholine showed that 16:00,16:1 Omega 7C, 18:1 Omega 7C, 18:1 Omega 9C, 115:0, cy19:0 Omega 8C, 10Me16:0 were the dominant groups of soil microbes in the study area, and the abundance of bacteria was the highest, followed by actinomycetes and fungi. The relative content of the negative bacteria in the East and the northwest of the study area is higher; the high value area of gram-positive and actinomycetes is located in the northwest of the study area; the high value area of the fungi is mainly distributed in the southern part of the area. In heavy metal contaminated soil, Gram-negative bacteria have more advantages than Gram-positive bacteria; fungi and heavy metals are negatively related to heavy metals; the ratio of fungi and bacteria is negatively correlated with Cd, indicating that soil heavy metal pollution in the study area leads to the degradation of soil ecosystem stability; the positive correlation between cy/pre and heavy metals indicates heavy metal pollution. .RDA analysis of soil microbial community structure in the study area showed that environmental factors co explained the variation of microbial community structure 39.8%, among which the variation of soil physical and chemical properties explained 33.4%, the variation of heavy metal interpretation was the main influencing factors of soil microbial community structure of 14.7%., electrical conductivity (EC), organic carbon (OC). Heavy metals, mechanical components and aluminum oxide. (6) Shannon index, Pielou uniformity index and Simpson dominance index are similar in spatial distribution, and high value areas all exist in the southwest of the study area. Correlation analysis shows that there is a significant positive correlation between the three diversity indices and heavy metals, indicating that heavy metal pollution in the soil of this study area is micro There is a moderate degree of stress in organisms, resulting in increased microbial diversity and evenness and dominance reduction.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：X53;S154.3

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