城市土壤中黑碳的特征与溯源及其环境意义
发布时间：2018-07-29 08:49
【摘要】：本论文以鞍山城市土壤为研究对象,对城市土壤中黑碳的浓度、空间分布以及溯源等进行了研究。研究采集115个城市表土和4个土壤剖面样本,利用化学氧化法测定城市土壤中的黑碳(BC)和总碳(TC)浓度,并分析了它们的空间分布规律和来源。结果表明鞍山城市表土中黑碳的浓度介于1.86～346.46g/kg之间,平均浓度为33.86g/kg,黑碳占土壤中总碳比例的平均值为75.73%。土壤剖面中BC和TC的浓度随着深度的增加而减少,而BC/TC比值随剖面深度的变化不明显。城市土壤BC浓度的空间分布图表明,高浓度的黑碳区位于城市北部,系该市钢铁生产企业分布区。表土中BC的富集系数(EF)介于0.28和37.23之间,平均值为5.11,表明城市表层土壤中BC呈中等或严重的累积。土壤颗粒中BC的粒级分布表明,BC的分布系数(DF)以1000-500μm粒级最高,50-2μm粒级最低。而250-50μm和50-2μm这两级BC的质量负荷系数(GSF)占76.2%,表明BC容易在这两级土壤粒级中累积。土壤中BC和重金属负荷污染指数(PLI)之间具有很强的相关性,表明土壤中BC和重金属具有相同的来源。土壤中BC/TC比在0.45～0.97之间,平均值为0.75。BC/TC的比值可以用来识别BC的来源。钢铁工业区采集的土壤样品中,BC/TC比值的平均值为0.88,表明BC主要来源于煤炭的燃烧。土壤中BC浓度和BC/TC比值可以反映城市土壤中人类活动的影响程度和污染源,可作为指示土壤中人为污染的指标。黑碳(BC)是参与许多地质和环境过程的一种关键碳。利用元素分析、扫描电子显微镜和能散x射线能谱(SEM/EDS)、傅里叶变换红外光谱(FTIR)、热重分析(TGA)、X射线衍射(XRD)和稳定碳同位素(δ13C)等方法对城市土壤中BC的化学成分、形貌、分子结构和碳稳定同位素进行了研究。元素分析结果表明,黑碳中碳元素含量平均超过70%,H/C和O/C摩尔原子比的平均值分别为0.73和0.18。BC颗粒的显微图像显示了 BC的不同形态,主要有多孔球形,不规则多孔碎块以及块状颗粒。其中,多孔球形BC颗粒的O/C摩尔原子比范围在0.04和0.37之间,表明这些BC颗粒主要来源于煤炭的燃烧。BC的XRD结果显示,BC结合的矿物主要有赤铁矿(Fe2O3),高岭石(Al2Si2O5(OH)4),石英(SiO2)和方解石(CaCO3)。傅里叶红外光谱显示BC的主要化学键为:3400cm-1的O-H键,2920 cm-1的 C=H 键,1600 cm-1的 C=C 键,1230 cm-1 的 C=O 键以及 1070 cm-1 的 C=O 键。BC的稳定碳同位素(δ13C)值范围为-24.48‰～-23.18‰,平均值为-23.79‰±0.39。BC中O/C摩尔原子比和碳同位素(δ13C)表明,它们主要来自化石燃料燃烧。因此,城市土壤中黑碳的浓度可以记录大气污染的历史,可作为区分城市环境污染源指标。围绕BC与重金属的相关性,研究了城市土壤黑碳中的重金属分布、迁移性和潜在环境风险。以10个代表性土壤的黑碳颗粒为材料,按照颗粒大小将BC分为三级,测定了重金属(Cd、Cr、Cu、Pb、Zn和Ni)的浓度,并利用毒性淋溶试验(TCLP)和EDTA浸提法评价了黑碳中重金属的生物有效性和淋溶性。结果表明,黑碳中重金属的浓度随着颗粒粒径的减小而增加,尤其以50μm粒径的BC中重金属浓度最高,重金属的富集系数(EFs)随着黑碳粒级的减小而增大,尤其以Cd和Zn富集最为严重。表明细颗粒黑碳积累较多的重金属,具有较大的重金属污染风险。细粒黑碳颗粒中重金属的分布系数(DFs)为Zn(3.22)Cu(2.84)Pb(2.61)Cr(2.19)Cd(2.05)。同时,根据 TCLP 和 EDTA 的淋溶性测定表明Cd和Zn比其他重金属有较高的淋溶性和生物有效性。根据上述研究,可以认为细黑碳颗粒是潜在有毒金属的重要来源,而不同粒级黑碳中重金属含量的变化在环境评估中也应该被考虑。为了进一步理解不同生物质燃烧源BC的特性,采集了21种不同的生物质原料,开展了不同热解温度和时间条件下生物质燃烧源BC特性的研究。生物质燃烧源BC特性的表征包括元素分析(C、H、O、N)、灰分、产量、pH值、EC、总碳、阳离子交换量、官能团(酸、碱、酚和羧基)和表面负电荷等。结果表明,黑碳中C含量、pH值和EC随着热解温度的增加而增加;而H、O、N含量、总碳(TC)、阳离子交换量(CEC)、黑碳产率和表面负电荷则随着裂解温度下降而降低。含氧官能团中,酸性官能团随着热解温度的升高而增加,而其他三种官能团则随着热解温度的增加而降低。对黑碳的基本性质进行相关性分析、主成分分析和聚类分析,结果发现黑碳的pH值同总碳含量,灰分含量,EC,羧基以及表面负电荷呈显著相关;主成分分析表明黑碳的性质可以分成四个主成分。根据聚类分析,21种黑碳可以分为四类。研究结果表明,生物质燃烧源黑碳的理化性质在很大程度上依赖于原料,黑碳理化性质的差异有助于理解土壤中BC的来源。城市土壤中黑碳的来源很广泛,我们研究了六种黑碳颗粒的基本性质以及黑碳与土壤矿物的相互作用。其中,利用元素分析、SEM/EDS、FTIR、XRD等对不同来源黑碳的基本性质进行研究。结果表明,除了污泥黑碳的碳含量较低,大约36%外,其余五种黑碳的碳含量均大约50%。黑碳的傅里叶红外光谱显示主要化学键的位置,其中,具体为3400cm-1的O-H键,1600cm-1的C=C键,1230 cm-1的C=O键以及1070 cm-1的C=O键。XRD分析表明,六种黑碳颗粒的矿物组成差异明显,尤其ASBC样品更为特殊,仅它含有赤铁矿以及2920 cm-1处的C=H键。SEM图像显示不同来源的黑碳颗粒具有不同的形态,其中生物黑碳孔隙规律,边缘锋利,几乎没有球形结构,而煤质黑碳呈孔隙不规律,多孔球形或者块状结构。SEM观察发现黑碳颗粒和土壤矿物的相互作用方式有表面接触,表面嵌入以及内部结合。土壤中黑碳与矿物的相互作用是理解BC在环境中的持久性、环境行为和对土壤性质影响的重要内容。
[Abstract]:In this paper, the concentration, spatial distribution and traceability of black carbon in urban soil were studied in Anshan city soil. 115 urban topsoil and 4 soil profile samples were collected, and chemical oxidation method was used to determine the concentration of black carbon (BC) and total carbon (TC) in urban soil, and their spatial distribution and distribution were analyzed. The results show that the concentration of black carbon in the urban topsoil of Anshan is between 1.86 and 346.46g/kg, the average concentration is 33.86g/kg, the average ratio of black carbon to the total carbon in the soil decreases with the depth of BC and TC in the 75.73%. soil profile, but the BC/TC ratio is not obvious with the depth of the section. The space of BC concentration in urban soil is in space. The distribution map shows that the high concentration of black carbon area is located in the northern part of the city. The concentration coefficient (EF) of BC in the topsoil is between 0.28 and 37.23, with an average of 5.11, indicating that the BC in the surface soil of the city is medium or serious. The distribution of BC in the soil particles indicates that the BC distribution coefficient (DF) is 1000-500 mu m particles. At the highest level, the grain level of 50-2 mu m is the lowest. The mass load coefficient (GSF) of 250-50 m and 50-2 micron BC (GSF) accounts for 76.2%, indicating that BC is easy to accumulate in the grain grade of the two grade soil. The BC and heavy metal load pollution index (PLI) in the soil have a strong correlation, indicating that the soil BC and heavy metals have the same source. The BC/TC ratio in the soil is 0.45. To 0.97, the ratio of the average value of 0.75.BC/TC can be used to identify the source of BC. The average value of the BC/TC ratio in the soil samples collected in the iron and steel industrial area is 0.88, indicating that the BC mainly originates from the combustion of coal. The BC concentration and BC/TC ratio in the soil can reflect the degree of influence of human activity in the urban soil and the source of pollution, which can be used as an indication. Black carbon (BC) is a key carbon that participates in many geological and environmental processes. Using elemental analysis, scanning electron microscopy and energy dispersive X ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X ray diffraction (XRD) and stable carbon isotope (delta 13C), and other methods for BC in urban soil Chemical composition, morphology, molecular structure and carbon stable isotopes have been studied. Elemental analysis shows that the average content of carbon in black carbon is more than 70%, the average value of H/C and O/C molar ratio is 0.73 and 0.18.BC particles, respectively, showing different shapes of BC, which are mainly porous, irregular, porous and lumpy. Among them, the O/C molar ratio range of the porous spherical BC particles is between 0.04 and 0.37, indicating that these BC particles are mainly derived from the XRD results of coal combustion.BC, and that the BC binding minerals are mainly hematite (Fe2O3), kaolinite (Al2Si2O5 (OH) 4), quartz (SiO2) and calcite (CaCO3). Fourier infrared spectroscopy shows the main chemistry of BC. The key is: the O-H key of 3400cm-1, the C=H key of 2920 cm-1, the C=C key of the 1600 cm-1, the C=O key of 1230 cm-1, and the.BC stable carbon isotope (delta 13C) of 1070 cm-1 C=O key range from per thousand to per thousand, and the average value is shown by the molar ratio of molar atoms and carbon isotopes (delta), which are mainly from the combustion of fossil fuels. Therefore, the concentration of black carbon in urban soil can record the history of atmospheric pollution and can be used as an indicator of urban environmental pollution. Around the correlation between BC and heavy metals, the distribution, mobility and potential environmental risk of heavy metals in urban soil black carbon are studied. The black carbon particles in 10 representative soils are used as the material and BC according to the size of the particles. The concentration of heavy metals (Cd, Cr, Cu, Pb, Zn and Ni) was measured, and the bioavailability and leaching of heavy metals in black carbon were evaluated by toxic leaching test (TCLP) and EDTA leaching. The results showed that the concentration of heavy metals in black carbon was increased with the decrease of particle size, especially the heavy metal concentration in BC of 50 micron diameter. The concentration coefficient (EFs) of metal increases with the decrease of the black carbon particle size, especially in Cd and Zn. It shows that the heavy metals with more heavy black carbon accumulation have greater heavy metal pollution risk. The distribution coefficient of heavy metals in fine black carbon particles (DFs) is Zn (3.22) Cu (2.84) Pb (2.61) Cr (2.19) Cd (2.05). At the same time, it is based on TCLP and E. The leaching of DTA shows that Cd and Zn have higher leaching and bioavailability than other heavy metals. According to these studies, it is considered that fine black carbon particles are an important source of potential toxic metals, and the changes of heavy metals in different granular black carbon should be considered in environmental assessment. In order to further understand different biomass, the different biomass can be further understood. The characteristics of the combustion source BC were collected and 21 different biomass materials were collected. The BC characteristics of the biomass combustion source were carried out under different pyrolysis temperatures and time conditions. The characterization of the BC characteristics of the biomass combustion source included element analysis (C, H, O, N), ash, yield, pH, EC, total carbon, cation exchange, functional group (acid, alkali, phenol and carboxyl) and surface negative electricity. The results show that C content, pH value and EC in black carbon increase with the increase of pyrolysis temperature, while H, O, N content, total carbon (TC), cation exchange (CEC), black carbon yield and surface negative charge decrease with the decrease of pyrolysis temperature. In oxygen functional groups, the acidic group increases with the increase of pyrolysis temperature, while the other three functional groups The correlation analysis of the basic properties of black carbon, principal component analysis and cluster analysis showed that the pH value of black carbon was significantly correlated with the total carbon content, ash content, EC, carboxyl and surface negative charges, and the principal component analysis showed that the properties of black carbon could be divided into four main components. According to cluster analysis, 2 1 kinds of black carbon can be divided into four types. The results show that the physical and chemical properties of black carbon are largely dependent on the raw materials, the differences in physical and chemical properties of black carbon are helpful to understand the source of BC in the soil. The sources of black carbon in urban soil are very wide, and we have studied the basic properties of six kinds of black carbon particles and the black carbon and soil minerals. The basic properties of black carbon from different sources were studied by element analysis, SEM/EDS, FTIR, XRD and so on. The results showed that, in addition to the low carbon content of the sludge black carbon, about 36% outside, the other five kinds of black carbon content of about 50%. black carbon showed the position of the main chemical bonds in the Fourier infrared spectrum of the black carbon, which was specifically 3400cm The O-H key of -1, the C=C bond of 1600cm-1, the C=O key of 1230 cm-1 and the C=O bond.XRD analysis of the 1070 cm-1 show that the mineral composition of the six black carbon particles is distinct, especially the ASBC sample is more special. Only it contains hematite and the C=H key of 2920 cm-1 shows the different forms of black carbon particles from different sources, of which the biological black carbon pores are found. There is a regular gap, edge sharp, almost no spherical structure, but coal black carbon is irregular in pore, porous spherical or massive structure.SEM observation found that the interaction of black carbon particles and soil minerals has surface contact, surface embedding and internal binding. The interaction of black carbon and mineral in soil is to understand the persistence of BC in the environment, Environmental behavior and its impact on soil properties are important.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S153
本文编号：2152142
[Abstract]:In this paper, the concentration, spatial distribution and traceability of black carbon in urban soil were studied in Anshan city soil. 115 urban topsoil and 4 soil profile samples were collected, and chemical oxidation method was used to determine the concentration of black carbon (BC) and total carbon (TC) in urban soil, and their spatial distribution and distribution were analyzed. The results show that the concentration of black carbon in the urban topsoil of Anshan is between 1.86 and 346.46g/kg, the average concentration is 33.86g/kg, the average ratio of black carbon to the total carbon in the soil decreases with the depth of BC and TC in the 75.73%. soil profile, but the BC/TC ratio is not obvious with the depth of the section. The space of BC concentration in urban soil is in space. The distribution map shows that the high concentration of black carbon area is located in the northern part of the city. The concentration coefficient (EF) of BC in the topsoil is between 0.28 and 37.23, with an average of 5.11, indicating that the BC in the surface soil of the city is medium or serious. The distribution of BC in the soil particles indicates that the BC distribution coefficient (DF) is 1000-500 mu m particles. At the highest level, the grain level of 50-2 mu m is the lowest. The mass load coefficient (GSF) of 250-50 m and 50-2 micron BC (GSF) accounts for 76.2%, indicating that BC is easy to accumulate in the grain grade of the two grade soil. The BC and heavy metal load pollution index (PLI) in the soil have a strong correlation, indicating that the soil BC and heavy metals have the same source. The BC/TC ratio in the soil is 0.45. To 0.97, the ratio of the average value of 0.75.BC/TC can be used to identify the source of BC. The average value of the BC/TC ratio in the soil samples collected in the iron and steel industrial area is 0.88, indicating that the BC mainly originates from the combustion of coal. The BC concentration and BC/TC ratio in the soil can reflect the degree of influence of human activity in the urban soil and the source of pollution, which can be used as an indication. Black carbon (BC) is a key carbon that participates in many geological and environmental processes. Using elemental analysis, scanning electron microscopy and energy dispersive X ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X ray diffraction (XRD) and stable carbon isotope (delta 13C), and other methods for BC in urban soil Chemical composition, morphology, molecular structure and carbon stable isotopes have been studied. Elemental analysis shows that the average content of carbon in black carbon is more than 70%, the average value of H/C and O/C molar ratio is 0.73 and 0.18.BC particles, respectively, showing different shapes of BC, which are mainly porous, irregular, porous and lumpy. Among them, the O/C molar ratio range of the porous spherical BC particles is between 0.04 and 0.37, indicating that these BC particles are mainly derived from the XRD results of coal combustion.BC, and that the BC binding minerals are mainly hematite (Fe2O3), kaolinite (Al2Si2O5 (OH) 4), quartz (SiO2) and calcite (CaCO3). Fourier infrared spectroscopy shows the main chemistry of BC. The key is: the O-H key of 3400cm-1, the C=H key of 2920 cm-1, the C=C key of the 1600 cm-1, the C=O key of 1230 cm-1, and the.BC stable carbon isotope (delta 13C) of 1070 cm-1 C=O key range from per thousand to per thousand, and the average value is shown by the molar ratio of molar atoms and carbon isotopes (delta), which are mainly from the combustion of fossil fuels. Therefore, the concentration of black carbon in urban soil can record the history of atmospheric pollution and can be used as an indicator of urban environmental pollution. Around the correlation between BC and heavy metals, the distribution, mobility and potential environmental risk of heavy metals in urban soil black carbon are studied. The black carbon particles in 10 representative soils are used as the material and BC according to the size of the particles. The concentration of heavy metals (Cd, Cr, Cu, Pb, Zn and Ni) was measured, and the bioavailability and leaching of heavy metals in black carbon were evaluated by toxic leaching test (TCLP) and EDTA leaching. The results showed that the concentration of heavy metals in black carbon was increased with the decrease of particle size, especially the heavy metal concentration in BC of 50 micron diameter. The concentration coefficient (EFs) of metal increases with the decrease of the black carbon particle size, especially in Cd and Zn. It shows that the heavy metals with more heavy black carbon accumulation have greater heavy metal pollution risk. The distribution coefficient of heavy metals in fine black carbon particles (DFs) is Zn (3.22) Cu (2.84) Pb (2.61) Cr (2.19) Cd (2.05). At the same time, it is based on TCLP and E. The leaching of DTA shows that Cd and Zn have higher leaching and bioavailability than other heavy metals. According to these studies, it is considered that fine black carbon particles are an important source of potential toxic metals, and the changes of heavy metals in different granular black carbon should be considered in environmental assessment. In order to further understand different biomass, the different biomass can be further understood. The characteristics of the combustion source BC were collected and 21 different biomass materials were collected. The BC characteristics of the biomass combustion source were carried out under different pyrolysis temperatures and time conditions. The characterization of the BC characteristics of the biomass combustion source included element analysis (C, H, O, N), ash, yield, pH, EC, total carbon, cation exchange, functional group (acid, alkali, phenol and carboxyl) and surface negative electricity. The results show that C content, pH value and EC in black carbon increase with the increase of pyrolysis temperature, while H, O, N content, total carbon (TC), cation exchange (CEC), black carbon yield and surface negative charge decrease with the decrease of pyrolysis temperature. In oxygen functional groups, the acidic group increases with the increase of pyrolysis temperature, while the other three functional groups The correlation analysis of the basic properties of black carbon, principal component analysis and cluster analysis showed that the pH value of black carbon was significantly correlated with the total carbon content, ash content, EC, carboxyl and surface negative charges, and the principal component analysis showed that the properties of black carbon could be divided into four main components. According to cluster analysis, 2 1 kinds of black carbon can be divided into four types. The results show that the physical and chemical properties of black carbon are largely dependent on the raw materials, the differences in physical and chemical properties of black carbon are helpful to understand the source of BC in the soil. The sources of black carbon in urban soil are very wide, and we have studied the basic properties of six kinds of black carbon particles and the black carbon and soil minerals. The basic properties of black carbon from different sources were studied by element analysis, SEM/EDS, FTIR, XRD and so on. The results showed that, in addition to the low carbon content of the sludge black carbon, about 36% outside, the other five kinds of black carbon content of about 50%. black carbon showed the position of the main chemical bonds in the Fourier infrared spectrum of the black carbon, which was specifically 3400cm The O-H key of -1, the C=C bond of 1600cm-1, the C=O key of 1230 cm-1 and the C=O bond.XRD analysis of the 1070 cm-1 show that the mineral composition of the six black carbon particles is distinct, especially the ASBC sample is more special. Only it contains hematite and the C=H key of 2920 cm-1 shows the different forms of black carbon particles from different sources, of which the biological black carbon pores are found. There is a regular gap, edge sharp, almost no spherical structure, but coal black carbon is irregular in pore, porous spherical or massive structure.SEM observation found that the interaction of black carbon particles and soil minerals has surface contact, surface embedding and internal binding. The interaction of black carbon and mineral in soil is to understand the persistence of BC in the environment, Environmental behavior and its impact on soil properties are important.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S153
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