三峡库区典型农业小流域溶解性有机质（DOM）的地球化学特征分析
发布时间：2019-05-18 21:43
【摘要】：三峡库区消落带作为敏感的生态环境系统,自蓄水以来,以其独特的“干湿交替”特征一直受到广泛关注。它是库区水体和周边陆地生态系统物质和能量转移与转化的活跃地带,具有缓冲带和植物护岸功能,对外界变化的响应相当敏感。以坡耕地为主的农业小流域系统,对库区消落带生态环境质量起着重要作用。DOM作为全球碳循环的重要组成部分,它对全球气候变化有重要影响,也是生态系统中物质与能量循环的重要活性组分,与生态系统中诸多重要环节密切相关。由于DOM活跃的环境角色,农业小流域中DOM对临近水环境产生的重要影响,无疑会进一步影响该区域内营养元素、重金属、有机污染物及温室气体等的环境行为。基于此,本研究选取了三峡库区消落带典型农业小流域——重庆涪陵区王家沟小流域为对象,结合紫外可见及荧光光谱手段对该流域内不同利用类型土壤DOM和不同类型水体DOM以及两条小流域出口水DOM的季节变化进行监测分析,以期阐明典型农业小流域土壤和水体中DOM地球化学特征的异质性,结果表明:(1)不同土地利用条件下DOM性质差异明显,以林地土壤DOM的芳香性程度较高,腐殖化特征最强,其次为田地;尽管居民用地和菜地溶解性有机碳(DOC)含量高(均值分别为80.69 mg·L-1和89.20 mg·L-1),但是芳香化程度低,DOM中非生色组分对高DOC含量的贡献明显。所有样本荧光指数(FI)介于自生源特征(FI=1.9)和陆源特征(FI=1.4)之间,自生(类蛋白组分)和异生源(类腐殖组分)对DOM均有贡献。大部分土壤样本类蛋白/类腐殖荧光组分(r(T/C))都大于2.0,说明该农业小流域土壤DOM受外来因素尤其是人类活动影响较大,尤以菜地为代表。另外,不同紫外可见和荧光光谱参数对不同土地利用条件下DOM结构和性质差异性的灵敏程度不同,光谱斜率比值(SR)和腐殖化指数(HIX)不能反映DOM地化特征的差异性,因此单一的紫外可见或者荧光光谱指标并不能全面提供DOM的特征信息,建议两种光谱分析方法联用。(2)溶解性有机质(DOM)作为重要的地球化学因子,在流域水体环境中扮演着重要的作用。该农业小流域水体dom空间差异较大,其组成和来源均存在明显不同。有色溶解性有机质(cdom)在dom中所占比例(ag*(355))大小顺序为:稻田水沟渠水池塘水井水出口水,其中稻田水和沟渠水的suva254较井水和出口水大,芳香性更明显。三维荧光光谱中存在2类4个荧光峰(a、c和b、t),dom来源都是内部(微生物、藻类)以及外源(腐殖质)的双重贡献。除自生源微生物活动的影响外,外源生活污水和农业生产用水的影响也是导致dom组分中类蛋白组分增多的重要原因。对比了不同种植季时相同位置水样dom光谱特征,类蛋白组分是控制两个种植季水体dom特征波动的重要因素。土地使用方式变化后水体doc、cdom和dom当中的r(t/c)存在明显差异,而fi、自生源指数(bix)和短波处/长波处类腐殖荧光组分(r(a/c))差异不显著。(3)不同土地利用类型土壤doc库容量差异较大,呈现出不同地化特征。其中以菜地doc库容量最大为0.798mg·g-1,结构较为复杂;田地最低为0.237mg·g-1。dom中非生色组分对高doc含量具有重要贡献。不同提取比例的cdom与doc不存在显著性相关性(p0.05)。主成分分析结果表明doc库容量变化受到自生源微生物活动及外来人为因素等共同的影响。由于受到外部光降解及人为因素等的综合影响,四种类型土壤doc库容量与dom各光谱参数的相关性不尽相同,单一的光谱指标并不能准确的反映出doc库容量变化情况,建议紫外和荧光光谱两种指标联合分析。吸附平衡常数ks与溶解性有机碳库容量[doc]具有极显著性正相关,吸附常数大的土壤具有较高的doc库容量。(4)小流域全年出口水样dom的荧光有机物(fdom)、cdom分别与doc表现出极显著的相关性(p0.05),不同采样时间doc浓度大小顺序为:4月11月7月1月。doc浓度全年变化范围在1.22~165.00mg·l-1之间,cdom浓度[a(355)]变化范围在0.08~24.47m-1,fdom浓度[fn(355)]变化范围为2063.80~102811.99m-1。不同采样时间类蛋白物质(peakb和peakt)荧光强度的顺序为4月11月7月1月。fi值年季变化范围为1.55~1.75,介于陆源特征值1.40和内源贡献值1.90之间,dom受内源贡献和外源输入的综合影响。两条小流域sub-1和sub-2的自生源贡献、芳香性、疏水性组分大小、分子量均存在显著性差异。夏季农业小流域水体dom腐殖化程度最高,自生源特征较明显,类蛋白组分贡献较大,生物可利用性较高;春、秋季水样dom腐殖化程度居中,冬季最弱。农业小流域水体thg和表征dom分子量大小的sr存在极显著正相关性(p0.05),而与fi显著负相关(p0.05)。dhg与a(355)、sr也存在极显著性正相关(p0.05),而与fi显著负相关(p0.05)。(5)溶解性有机质(dom)是水体生态系统的重要组成部分,其性质和结构决定了其在污染物环境行为中扮演着重要角色(例如对汞的迁移转化的影响)。另外,SUVA254和DOC与各形态Hg无明显相关性,但水体生色组分和分子量大小是控制溶解态和活性汞的重要因素;甲基汞变化可能与水体初级生产力导致的有机质富集和迁移关系密切。
[Abstract]:As the sensitive ecological environment system of the Three Gorges Reservoir, its unique "dry and wet alternation" characteristics have been widely concerned since the water storage. It is an active area of the physical and energy transfer and transformation of the water and surrounding land ecosystem in the reservoir area, and has the function of buffer zone and plant bank protection, and is quite sensitive to the response of the external change. The agricultural small watershed system, which is based on the slope land, plays an important role in the ecological environment quality of the reservoir in the reservoir area. As an important part of the global carbon cycle, DOM has an important influence on the global climate change, and it is also an important active component of the material and energy circulation in the ecosystem, which is closely related to many important links in the ecosystem. Because of the active role of the DOM, the important influence of the DOM on the water environment in the agricultural small watershed will undoubtedly further affect the environmental behavior of the nutrient elements, heavy metals, organic pollutants and greenhouse gases in the region. On the basis of this, the study has selected the small watershed of Wangjiagou, the typical agricultural small watershed in the Three Gorges Reservoir area, which is the object of the small watershed. in ord to clarify that heterogeneity of the DOM geochemical characteristics in the soil and the water body of the typical agricultural small watershed, The results show that: (1) The difference of DOM in different land-use conditions is obvious, and the soil DOM of the forest land has a high degree of aromaticity, and the humification is the strongest, and the second is the field; Although the content of soluble organic carbon (DOC) was high (80.69 mg 路 L-1 and 89.20 mg 路 L-1, respectively), the degree of aromatalization was low and the contribution of the non-chromophoric component in the DOM to the high DOC content was significant. The fluorescence index (FI) of all samples is between the self-source characteristics (FI = 1.9) and the land-source characteristics (FI = 1.4), and the self-generated (class-like component) and the isogenic (species-like humic components) contribute to the DOM. Most of the soil sample class protein/ humic fluorescent component (r (T/ C)) is greater than 2.0, indicating that the soil DOM of the agricultural small watershed is influenced by external factors, especially human activities, especially in the vegetable field. in addition, that sensitivity of the different UV-and fluorescence spectral parameters to the difference of the DOM structure and the property in different land-use conditions is different, and the ratio of the spectral slope (SR) and the humification index (HIX) cannot reflect the difference of the characteristic of the DOM, Therefore, the single ultraviolet-visible or fluorescent spectrum index can not provide the characteristic information of the DOM in a comprehensive way, and it is suggested that the two spectral analysis methods can be used in combination. (2) The soluble organic matter (DOM) plays an important role in the water environment of the basin as an important geochemical factor. There is a large difference in the dom space between the water bodies in the small watershed, and the composition and the source of the water are obviously different. The order of the size of the colored soluble organic matter (cdrom) in the dom (ag * (355)) is: the water outlet of the water in the water and the water in the paddy field of the rice field, wherein the suva254 of the rice field water and the ditch water is larger than the well water and the outlet water, and the aromatic property is more obvious. There are four fluorescence peaks (a, c and b, t) in the three-dimensional fluorescence spectrum, both of which are the dual contribution of the inside (micro-organisms, algae) and the foreign (humus). In addition to the influence of the microbial activity of the biogenic source, the influence of the exogenous domestic sewage and the water for agricultural production is also an important cause of the increase of the protein-like components in the dom component. The dom spectral characteristics of the water samples at the same location in different planting season are compared, and the component of the class protein is an important factor to control the fluctuation of the dom characteristics of the two planting seasons. There was a significant difference in r (t/ c) among the water body doc, cdrom and dom after the change of the land use method, and the difference of fi, the self-source index (bix) and the humification fluorescent component (r (a/ c)) at the short-wave and long-wave sites was not significant. (3) The different types of soil doc storage capacity of different land use types show different characteristics. The maximum capacity of doc is 0.798 mg 路 g-1, the structure is more complex, the lowest of the field is 0.237 mg 路 g-1.dom, the non-chromophoric component has an important contribution to the high doc content. There was no significant correlation between ccom and doc in different extraction ratios (p0.05). The results of principal component analysis show that the change of the capacity of doc library is influenced by the self-source microbial activity and the external human factors. Due to the comprehensive influence of external photodegradation and human factors, the correlation between the capacity of the four types of soil doc and the parameters of dom's spectral parameters is different, and the single spectral index can not accurately reflect the change of the capacity of the doc library, and it is suggested that the combination of the two indexes of the ultraviolet and the fluorescence spectrum can be combined. The adsorption equilibrium constant ks has a very significant positive correlation with the dissolved organic carbon library capacity[doc], and the soil with large adsorption constant has higher doc storage capacity. (4) The fluorescence organic matter (fdom) and cdrom of the water sample dom in the whole year of the small watershed were significantly correlated with the doc (p0.05). The order of the concentration of the different sampling time doc was: April, November, November. The variation range of the concentration of doc (a (355)] in the range of from 1.22 to 165.00 mg 路 l-1 and the concentration of fdom[a (355)] varied from 0.08 to 24.47 m-1, and the range of fdom concentration[fn (355)] ranged from 2063.80 to 102811.99 m-1. The order of the fluorescence intensity of a different sample time class of protein material (peakb and peakt) was April, November, November. The variation range of fi-value is 1.55-1.75, between the land-source characteristic value 1.40 and the intrinsic contribution value of 1.90, and dom is influenced by the endogenous contribution and the exogenous input. There was a significant difference in the self-source contribution, the aromaticity, the hydrophobic component size and the molecular weight of the sub-1 and sub-2 of the two small watersheds. In summer, the degree of water dom in the small watershed is the highest, the self-source is more obvious, the component of the class protein is relatively large, and the bioavailability is high; in the spring, the water sample of autumn is in the middle of the humification degree, and the winter is the weakest. There was a significant positive correlation between the water content (thg) and the sr (p0.05), and the significant negative correlation with fi (p0.05), and a significant negative correlation with fi (p0.05), while there was a significant negative correlation with fi (p0.05). (5) Dissolved organic matter (Dom) is an important part of the water body ecosystem, and its nature and structure decide that it plays an important role in the environmental behavior of the pollutants (for example, the effect on the migration and transformation of the mercury). In addition, there is no significant correlation between SUVA 254 and DOC, but the color and molecular weight of the water body are important factors for controlling the dissolved state and active mercury; the change of methylmercury may be closely related to the enrichment and migration of organic matter caused by primary productivity of the water body.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X52
[Abstract]:As the sensitive ecological environment system of the Three Gorges Reservoir, its unique "dry and wet alternation" characteristics have been widely concerned since the water storage. It is an active area of the physical and energy transfer and transformation of the water and surrounding land ecosystem in the reservoir area, and has the function of buffer zone and plant bank protection, and is quite sensitive to the response of the external change. The agricultural small watershed system, which is based on the slope land, plays an important role in the ecological environment quality of the reservoir in the reservoir area. As an important part of the global carbon cycle, DOM has an important influence on the global climate change, and it is also an important active component of the material and energy circulation in the ecosystem, which is closely related to many important links in the ecosystem. Because of the active role of the DOM, the important influence of the DOM on the water environment in the agricultural small watershed will undoubtedly further affect the environmental behavior of the nutrient elements, heavy metals, organic pollutants and greenhouse gases in the region. On the basis of this, the study has selected the small watershed of Wangjiagou, the typical agricultural small watershed in the Three Gorges Reservoir area, which is the object of the small watershed. in ord to clarify that heterogeneity of the DOM geochemical characteristics in the soil and the water body of the typical agricultural small watershed, The results show that: (1) The difference of DOM in different land-use conditions is obvious, and the soil DOM of the forest land has a high degree of aromaticity, and the humification is the strongest, and the second is the field; Although the content of soluble organic carbon (DOC) was high (80.69 mg 路 L-1 and 89.20 mg 路 L-1, respectively), the degree of aromatalization was low and the contribution of the non-chromophoric component in the DOM to the high DOC content was significant. The fluorescence index (FI) of all samples is between the self-source characteristics (FI = 1.9) and the land-source characteristics (FI = 1.4), and the self-generated (class-like component) and the isogenic (species-like humic components) contribute to the DOM. Most of the soil sample class protein/ humic fluorescent component (r (T/ C)) is greater than 2.0, indicating that the soil DOM of the agricultural small watershed is influenced by external factors, especially human activities, especially in the vegetable field. in addition, that sensitivity of the different UV-and fluorescence spectral parameters to the difference of the DOM structure and the property in different land-use conditions is different, and the ratio of the spectral slope (SR) and the humification index (HIX) cannot reflect the difference of the characteristic of the DOM, Therefore, the single ultraviolet-visible or fluorescent spectrum index can not provide the characteristic information of the DOM in a comprehensive way, and it is suggested that the two spectral analysis methods can be used in combination. (2) The soluble organic matter (DOM) plays an important role in the water environment of the basin as an important geochemical factor. There is a large difference in the dom space between the water bodies in the small watershed, and the composition and the source of the water are obviously different. The order of the size of the colored soluble organic matter (cdrom) in the dom (ag * (355)) is: the water outlet of the water in the water and the water in the paddy field of the rice field, wherein the suva254 of the rice field water and the ditch water is larger than the well water and the outlet water, and the aromatic property is more obvious. There are four fluorescence peaks (a, c and b, t) in the three-dimensional fluorescence spectrum, both of which are the dual contribution of the inside (micro-organisms, algae) and the foreign (humus). In addition to the influence of the microbial activity of the biogenic source, the influence of the exogenous domestic sewage and the water for agricultural production is also an important cause of the increase of the protein-like components in the dom component. The dom spectral characteristics of the water samples at the same location in different planting season are compared, and the component of the class protein is an important factor to control the fluctuation of the dom characteristics of the two planting seasons. There was a significant difference in r (t/ c) among the water body doc, cdrom and dom after the change of the land use method, and the difference of fi, the self-source index (bix) and the humification fluorescent component (r (a/ c)) at the short-wave and long-wave sites was not significant. (3) The different types of soil doc storage capacity of different land use types show different characteristics. The maximum capacity of doc is 0.798 mg 路 g-1, the structure is more complex, the lowest of the field is 0.237 mg 路 g-1.dom, the non-chromophoric component has an important contribution to the high doc content. There was no significant correlation between ccom and doc in different extraction ratios (p0.05). The results of principal component analysis show that the change of the capacity of doc library is influenced by the self-source microbial activity and the external human factors. Due to the comprehensive influence of external photodegradation and human factors, the correlation between the capacity of the four types of soil doc and the parameters of dom's spectral parameters is different, and the single spectral index can not accurately reflect the change of the capacity of the doc library, and it is suggested that the combination of the two indexes of the ultraviolet and the fluorescence spectrum can be combined. The adsorption equilibrium constant ks has a very significant positive correlation with the dissolved organic carbon library capacity[doc], and the soil with large adsorption constant has higher doc storage capacity. (4) The fluorescence organic matter (fdom) and cdrom of the water sample dom in the whole year of the small watershed were significantly correlated with the doc (p0.05). The order of the concentration of the different sampling time doc was: April, November, November. The variation range of the concentration of doc (a (355)] in the range of from 1.22 to 165.00 mg 路 l-1 and the concentration of fdom[a (355)] varied from 0.08 to 24.47 m-1, and the range of fdom concentration[fn (355)] ranged from 2063.80 to 102811.99 m-1. The order of the fluorescence intensity of a different sample time class of protein material (peakb and peakt) was April, November, November. The variation range of fi-value is 1.55-1.75, between the land-source characteristic value 1.40 and the intrinsic contribution value of 1.90, and dom is influenced by the endogenous contribution and the exogenous input. There was a significant difference in the self-source contribution, the aromaticity, the hydrophobic component size and the molecular weight of the sub-1 and sub-2 of the two small watersheds. In summer, the degree of water dom in the small watershed is the highest, the self-source is more obvious, the component of the class protein is relatively large, and the bioavailability is high; in the spring, the water sample of autumn is in the middle of the humification degree, and the winter is the weakest. There was a significant positive correlation between the water content (thg) and the sr (p0.05), and the significant negative correlation with fi (p0.05), and a significant negative correlation with fi (p0.05), while there was a significant negative correlation with fi (p0.05). (5) Dissolved organic matter (Dom) is an important part of the water body ecosystem, and its nature and structure decide that it plays an important role in the environmental behavior of the pollutants (for example, the effect on the migration and transformation of the mercury). In addition, there is no significant correlation between SUVA 254 and DOC, but the color and molecular weight of the water body are important factors for controlling the dissolved state and active mercury; the change of methylmercury may be closely related to the enrichment and migration of organic matter caused by primary productivity of the water body.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X52
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8 肖q辖，
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