南京城市林业土壤黑碳空间分布及与多环芳烃的相关分析

发布时间：2018-07-29 20:05

【摘要】：黑碳是由煤和石油等化石燃料不完全燃烧和秸秆等生物质燃烧所产生的具有高度热稳定性的含碳物质,广泛分布于大气、土壤、冰雪和水以及沉积物中,对全球变暖、区域气候、环境与健康等方面有重要影响。本实验中在南京市主城区采用10km*10km网格取样法采集土壤样本162个以及选取南京市8个典型功能区(垃圾填埋场区、工厂区、道路绿化带区、交通枢纽区、教学区、居民区、城区天然林、郊区天然林),每个功能区采样2km*2km网格采集3个样点,每个样点采集三0~20cm;20~40cm;40~60cm三个层次的样品,用热化学法测定土壤中黑碳的含量,并基于ArcGIS地统计学分析和SPSS相关性分析,分析城市林业土壤中黑碳含量的总体空间分布、不同功能区黑碳含量以及城市林业土壤中黑碳含量与总有机碳含量、多环芳烃(PAHs)含量的相关关系,进而探讨黑碳的来源与影响黑碳分布的影响因素。主要研究结果如下:1、南京主城区城市林业土壤中黑碳的浓度范围为0.7245g/kg~13.9340g/kg,平均值为4.429g/kg,呈现出比较明显的空间差异。南京市主城区林业土壤的黑碳含量分布具有一定的连续性,高值出现集中,由中间向南北两侧呈现递减趋势,即由市中心向两侧郊区呈递减趋势。从空间上看,黑碳含量的高值出现在市中心交通枢纽处如汽车东站、新庄交通枢纽、鼓楼新街口等交通繁华地段。说明黑碳含量受机动车燃油不完全燃烧影响大。空间插值图也反映出城市林土壤中黑碳的含量除受汽车尾气的影响还受人类活动扰动的影响。2、南京市主城区城市林业土壤中总有机碳含量和黑碳含量的插值预测图上高值部分有重叠部分,整个图形斑块分布也有相似性。黑碳含量与总有机碳含量具有显著相关关系,(p0.01),其Pearson相关系数为0.876。说明黑碳对在城市林业土壤有机碳的固定具有重要的作用,有利于稳定土壤结构,维持土壤肥力,防止土壤退化。3、南京市主城区城市林业土壤中大部分黑碳与有机碳含量的比值(BC/TOC)为0.5~0.7左右,认为黑碳主要来源于化石燃料的燃烧。郊区天然林BC/TOC为0.13,认为该地区黑碳主要来源生物质燃烧。不同功能区土壤的黑碳含量具有差异性,交通枢纽区和道路绿化带的含量较高主要源于汽车燃油不完全燃烧。而且随着城市不断的发展,各功能区的界限也日渐模糊,环境互相渗透,互相交杂,黑碳含量在各功能区的差异也渐缩小。4、南京市主城区城市林业土壤中PAHs主要来源为燃烧源。几乎所有功能区土壤黑碳含量、总有机碳含量均与ΣPAHs有显著相关性,部分相关系数达到0.8~0.9左右,主要原因为在相同的功能区它们有着相同的来源。虽然PAHs的分布同时受到有机碳和黑碳的显著影响,但是受黑碳的影响更为显著。而且相比于低环数PAHs,高环数的PAHs更能受到有机碳、黑碳的影响,这是由于高环数PAHs分子量比较高,它的化学性质更加稳定,不易挥发。
[Abstract]:Black carbon is a highly thermal stable carbon-containing substance produced by incomplete combustion of fossil fuels such as coal and petroleum and biomass such as straw, and is widely distributed in the atmosphere, soil, snow, ice and water, as well as in sediments, contributing to global warming. Regional climate, environment and health have important effects. In this experiment, 162 soil samples were collected by 10km*10km grid sampling method in the main urban area of Nanjing, and 8 typical functional areas (landfill, factory, road green belt, transportation hub, teaching area, residential area) were selected in Nanjing. Natural forest in urban area and natural forest in suburb). Three samples were collected from 2km*2km grid in each functional area, and 30 ~ 20 cm ~ (20) ~ (20) ~ (40) cm ~ (40) cm ~ (60 cm) samples were collected from each sampling spot. The content of black carbon in soil was determined by thermochemical method. Based on ArcGIS geostatistics analysis and SPSS correlation analysis, the total spatial distribution of black carbon content in urban forestry soil, black carbon content in different functional areas, black carbon content and total organic carbon content in urban forestry soil were analyzed. The relationship between the (PAHs) content of PAHs and the sources of black carbon and the factors affecting the distribution of black carbon were discussed. The main results are as follows: 1. The concentration range of black carbon in urban forestry soil is 0.7245g / kg ~ 13.9340g 路kg ~ (-1), the average value is 4.429g / kg ~ (-1), showing obvious spatial difference. The distribution of black carbon in forestry soil of Nanjing city has a certain continuity, the high value is concentrated, and the trend is decreasing from the middle to the north and south, that is, from the city center to the suburbs of both sides. From the space point of view, the high value of black carbon content appears in the downtown transportation hub such as the east station of automobile, Xinzhuang traffic hub, Gulou Xinjiakou and other traffic bustling areas. It shows that the black carbon content is greatly affected by incomplete combustion of motor vehicle fuel. The spatial interpolation map also shows that the black carbon content in urban forest soil is affected not only by the automobile exhaust but also by the disturbance of human activities. The interpolation prediction of total organic carbon content and black carbon content in the urban forestry soil of the main urban area of Nanjing city is also shown. The high-value part of the graph has overlaps, The pattern distribution of patches is also similar. There was a significant correlation between black carbon content and total organic carbon content (p0.01), and the Pearson correlation coefficient was 0.876. The results show that black carbon plays an important role in the fixation of organic carbon in urban forestry soil, which is helpful to stabilize soil structure and maintain soil fertility. To prevent soil degradation, the ratio of black carbon to organic carbon content (BC/TOC) in the urban forestry soil of the main urban area of Nanjing is about 0.50.7.It is considered that the black carbon mainly comes from the burning of fossil fuels. The BC/TOC of natural forest in suburban area is 0.13, which is considered to be the main source of biomass combustion. The black carbon content of soil in different functional areas is different, and the high content of traffic hub and road green belt is mainly due to incomplete combustion of automobile fuel. With the continuous development of the city, the boundary of each functional area is increasingly blurred, the environment infiltrates and intermingles with each other, and the difference of black carbon content in each functional area is reduced gradually. The main source of PAHs in the urban forestry soil of the main urban area of Nanjing is the combustion source. Soil black carbon content and total organic carbon content in almost all functional areas were significantly correlated with 危 PAHs, and the partial correlation coefficient was about 0.80.9.The main reason was that they had the same sources in the same functional areas. Although the distribution of PAHs is significantly affected by both organic carbon and black carbon, the distribution of PAHs is more significantly affected by black carbon. Compared with the low ring number, PAHs with high ring number is more affected by organic carbon and black carbon, which is due to the high molecular weight of high ring number PAHs, its chemical property is more stable, and it is not easy to volatilize.
【学位授予单位】：南京林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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