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题名: 城市生态系统氮代谢排放特征分析
作者: 冼超凡1
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 欧阳志云
关键词: 活性氮,排放强度,氮溯源,氮补偿,城市化 ; Reactive nitrogen, Emission intensity, Nitrogen source apportionment,Nitrogen offset, Urbanization
其他题名: Characteristics of emissions from nitrogen metabolism in urban ecosystems
学位专业: 生态学
中文摘要: 随着全球快速城市化,人类活动已经强烈改变营养元素氮素的生物地球化学 循环过程。对于人类主导的异养型城市生态系统,其消耗氮素的同时,直接或间 接导致含有大量人为活性氮原子的含氮化合物(Nr)流失到环境中,带来了巨大的 生态环境压力和严重的污染问题,其已被广泛视为继生物多样性丧失与全球变暖 后,第三个全球性环境问题。作为全球城市化最快的人口密集国家之一,中国逐 渐成为全球最大的人类源活性氮生产及周转区域。作为氮热点,城市生态系统在 氮代谢过程中存在一些核心问题,即以人类为核心的社会经济系统中氮供给与消 费关系的可持续发展及其对环境的影响,因此量化并评估活性氮流失所带来的负 面环境效应具有重要的科学和现实意义。 鉴于此,本研究围绕着上述问题,基于监测、实验室分析的数据、统计数据 以及国内外相关研究成果,建立适用于城市、区域等不同尺度的社会经济系统氮 代谢排放量化分析框架,估算了北京城市污水处理厂、北京城市、京津冀城市区 域的氮排放特征,分析了基于“氮补偿“措施的减排对策的可行性,从宏观政策 角度探讨了新时期我国城市化低氮发展的建议。同时,利用稳定同位素分析方法 重构城市污水硝酸盐同位素组分的标准范围,从技术角度提高城市水体氮污染溯 源工作的效率性与精确度,旨在从源头上为城市水体氮污染治理提供信息参考。 主要成果如下: (1)北京市海淀区 2014—2015年间城市污水无机氮浓度具有较显著的月变 化,氨氮是城市污水氮主要的存在形式。硝氮为排河尾水主要的污染氮形式,尾 水排放为城市污水处理主要氮排放途径,占总排放 98.35%。北京城市生态系统 污水氮净化过程中,氮排放强度月均为 31.15%,等量污水氮量去除在干冷季中 造成的环境“氮包袱”较大,同时,较为先进的处理工艺有助于减少此类“氮包 袱”。基于硝酸盐同位素的溯源方法能适用于此地区水体氮污染溯源。不完全反 硝化可能是排河尾水中的硝酸盐氮氧同位素组分比率升高的原因。应用基于实测 的污水溯源参考标准有助于提高水体氮污染溯源工作的精确度,为城市水体氮减 排工作的开展提供更有效的信息参考。 (2)北京市 1980—2012年间人均每年食物氮足迹排放在 14.69~22.58 kg N 之间波动增加,平均为 17.78 kg N,接近发达国家高氮消费水平;农村居民人均 食物氮足迹排放在 10.81~15.28 kg N之间波动减少,平均为 12.72 kg N。食物消 费量和消费模式的改变对居民食物氮足迹有一定的影响。随着北京城市化发展, 控制城镇人口数量和提倡合理低氮膳食是减缓区域氮足迹增长的重要途径。 (3)北京市在 2000—2012年间城市化过程中氮排放呈轻微上升趋势,年均 平均值为 0.19 Tg N,主要贡献源为能源燃烧排放。污水处理与垃圾处理导致的 二次排放不可忽视,其逐渐成为城市潜在的氮源。北京市居民生活及经济生产导 致的单位氮排放强度在研究期间间呈降低趋势。前者为人均生活排放3.87 kg N; 而后者为每亿元等值产品服务生产排放 16.74 t N。基于数据包络分析的氮减排效 率评价可知,北京市城市化过程氮减排效率较高,尤其在 2000—2006年间。基 于“氮补偿”机制的减排策略可为日后北京或其他城市氮减排政策提供一个新的 思路。 (4)京津冀区域在 2004—2014年间城市化过程中氮排放呈波动缓慢降低趋 势。其中,河北省一直是区域主要排放源,其气态与液态排放量分别占整个区域 的 79~84%和 74~79%。京津冀区域在研究期间的活性氮排放主要来源于农业活 动,而后逐渐转为工业生产与居民生活。城市化对区域各地氮排放强度的影响并 不一致,区域排放强度为年均 5.8 t N•km-2。基于数据包络分析分析的氮减排效 率评价可知,北京市氮减排效率相对最高,河北省次之,天津市最低。降低河北 省氮排放强度与提高天津氮减排效率是京津冀区域低氮城市化的关键。采用基于 协同“氮补偿”机制的减排策略,有助于实现二市一省互助互补可持续发展战略。
英文摘要: With rapid development of global urbanization, the biogeochemical cycling of nutrient element nitrogen was interfered by high-intensive human activities. Different from autotrophic natural ecosystem, urban ecosystem is a human-dominant and heterotrophic ecosystem, and it has brought the ecological pressure and serious environmentally pollution, resulting from direct and indirect emissions of anthropogenic reactive nitrogen (Nr) to environment during nitrogen consumption. This emerging challenging was widely supposed as the third global environmental problems sequent to biodiversity loss and global warming. As the most populous country with dramatic urbanization in the world, China was becoming the largest Nr producer with mobilizing the largest Nr cycling in the world. As the Nr hotspots, the sustainable development of nitrogen supply and consumption for anthropogenic social-economic system running along with its potential environmental impacts should be addressed during nitrogen metabolism of urban ecosystem. Thus,it is practical and meaningful to quantify and assess the negative environmental impacts resulting from Nr releasing. In this study, the aforementioned points will be targeted. Basing on a combination of field monitoring and experiments, statistical data and results of relevant literatures, the quantitative framework of socioeconomic nitrogen metabolism was established to gradually estimate Nr emissions in multi-scales ecosystem (wastewater treatment plant in Beijing, Beijing megacity,Beijing-Tianjin-Hebei agglomeration), and then analyze the feasibilities of emission reduction countermeasures based on ‘N offset’. In accordance with the estimations and analysis, suggestions on low-nitrogen development with urbanization in China were given from the perspectives of macropolicy. Meanwhile, a dual isotope approach was applied to explore the variation in nitrate isotopic signatures in urban sewage to improve the efficiency and precision of source apportionment from the view of technical reference, aiming at achieve further riverine Nr reduction from the sources. The results are as follows. (1)The nitrogen concentrations of urban sewage in Haidian district in Beijing presented obvious differences across mouths from 2014-2015. Ammonia nitrogen was the main of nitrogen pollution in untreated urban sewage, and nitrate nitrogen was the dominant nitrogen pollution in the discharged effluent, which was the main contributor (average 98.35%) to urban Nr emission to environemt resulting from sewage treatment. Monthly Nr emission intensity was 31.15%, and the Nr emiossion to water environement caused by the equivalent nitrogen removal was peaking in cold and dry seasons, during the process of sewage treatment in Beijing ecosystem. More advanced treatment technology can contribute to the reduction of Nr emission intensity. The feasibility of a dual nitrate isotope method was proposed for nitrogen source apportionment in this typical urban region. The treatment processing would result in the enrichment of nitrate isotopic compositions in discharged effluent, probably due to incomplete denitrification in this case. Application of refined nitrate isotopic compositions ranges conducted from field sampling was supposed to trace the nitrate sources to aquatic nitrogenous pollution more accurately, providing efficient references for urban water management to achieve aquatic Nr reduction. (2)The trend of food nitrogen footprints of urban residents in Beijing presented growing with fluctuation between 14.69-22.58 kg N per capita per year from 1980- 2012 with average 17.78 kg N per capita per year, which closed to the footprints level of residents in developed countries. As to the trend of food nitrogen footprints of rural residents, it presented slightly decreasing from 10.81-15.28 kg N per capita per year during the same period with 12.72 kg N as the average. The changing of food consumption and residential consumption patterns drove the trend of food nitrogen footprints to an extent. With continuous urbanization in Beijing, limiting the urban population size and promoting low-nitrogen diet are supposed to alleviate the growth of regional food nitrogen footprints. (3)Nr emissions from Beijing presented slightly increasing from 2000-2012, and the annual emission was 0.19 Tg N, mainly resulting from fuel combustion. The secondary Nr emissions resulting from sewage and garbage treatment should not be neglected, which gradually turned to be potential Nr sources. Nevertheless, the Nr emission intensities resulting from inhabitants’ livelihoods and material production had weakened over the study period, with average value of 3.87 kg N per capita and 16.74 t N per 100 million RMB. The evaluation based on DEA analysis showed that the environmental measures to remove Nr in Beijing were efficient in most years, especially during 2000-2006. The mitigation strategies based on ‘N offset’ mechanism, could provide theoretical support for Nr reduction in Beijing megacity or other cities. (4)Nr emissions from Beijing-Tianjin-Hebei agglomeration presented slightly decreased with fluctuation during urbanization from 2004-2014. Hebei province was the main contributor to Nr emission, occupying 79-84% and 74-79% of nitrogen loss to atmosphere and hydrosphere. The main sources of emission was agricultural activities primarily, and then turned to industrial activities and residential livelihood. The impacts of urbanization on reactive nitrogen emission intensity of each region were different. The annual emission intensity of this agglomeration was 5.8 t N/km2. The evaluation based on DEA analysis showed that Beijing city owned the highest of emission reduction efficiency, followed by Hebei province and Tianjin city. The keys for overall low-nitrogen urbanization were supposed to be the reduction in the emissions intensity of Hebei province and the improvement in emission reduction efficiency of Tianjin city. The countermeasures toward emission reduction, basing on collaborative ‘N offset’ mechanism, would contribute to the reciprocity among Beijing-Tianjin-Hebei agglomeration in emission reduction during sustainable development.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38713
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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作者单位: 1.中国科学院生态环境研究中心

Recommended Citation:
冼超凡. 城市生态系统氮代谢排放特征分析[D]. 北京. 中国科学院大学. 2017.
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