黑碳气溶胶排放清单校验的碳同位素方法研究

Black carbon (BC) aerosol play an important role in air quality and climate change. Emission inventory (EI) is a key parameter in studying the environmental and climate effects of BC, yet is poorly constrained and has a large uncertainty. Thus, there is an urgent need to assess BC-EI reliability by using an unbiased methodology in order to guide the improvement of BC-EI quality. Stable carbon isotope (δ13C) and radiocarbon (Δ14C) are powerful tools of source identification for BC. Given this, the project will break new grounds by providing accurate and repeatable results for source apportionment of BC in the receptor site (Taoyuan, Heshan) and in the air background site (Nanling, Shaoguan) of Pearl River Delta. By combining novel and powerful dual carbon isotopes (δ13C/Δ14C), the relative contributions of key emission sectors (coal, liquid petroleum, and biomass-burning) in BC will be quantitatively calculated. The project will further reveal the difference between two sampling sites for δ13C/Δ14C-based source apportionment, seasonal patterns, and the potential influencing factors. In addition, the dual carbon isotopic results will be further compared to the predictions from the “bottom-up” BC-EI, which is developed and managed by our group. This study will greatly improve our understanding of BC emission sources in Pearl River Delta, get the knowledge on the reliability of current BC-EI, reveal the impacts on atmospheric environment raised by anthropogenic activities, and provide a scientific guideline for delicacy management of air quality.

黑碳气溶胶（BC）在空气污染和气候变化上扮演着非常重要的角色。排放清单（EI）是研究BC环境和气候效应的关键参数，但存在明显不确定性，迫切需要一种独立客观的方法来评价BC-EI可靠性，以指导其后续的改进工作。稳定碳（δ13C）和放射性碳同位素（Δ14C）具有强大的溯源能力。基于此，项目以珠三角关键排放源碳同位素为基础数据，建立基于13C/14C分析的BC源解析模型，明确煤、石油和生物质对珠三角区域站（鹤山桃源）和国家环境空气本底站（韶关南岭）BC的相对贡献，探讨两站差别并揭示其季节变化规律和影响因素。利用自建BC-EI数据库得到BC源解析结果，与同位素结果进行对比，实现“自上而下”对“自下而上”方法的验证。项目成果有助于深入了解BC在珠三角区域和环境空气本底的排放来源，认识人类活动对大气环境的影响，评估目前该区域BC-EI的合理性，为空气质量的精细化管理提供科学依据。

黑碳气溶胶可对空气质量、气候系统和人体健康产生非常重要的影响。然而，由于长期缺乏较为客观和准确的溯源手段，当前学界对大气环境中的黑碳来源认识仍然不清，基于“自下而上”方法学建立的黑碳排放清单常存在巨大不确定性。放射性碳同位素分析是目前唯一可以对黑碳气溶胶的化石源和生物源进行准确区分和量化的手段。基于此，本项目1）更新了关键燃烧源黑碳的稳定碳同位素特征值，构建了耦合稳定碳同位素和放射性碳同位素的黑碳源解析方法，为准确识别和量化关键排放源对大气环境黑碳的影响提供了技术支撑；2）以珠三角为研究靶区，探讨了黑碳浓度的时空变化特征和影响因素，计算了煤炭、石油、以及生物质燃烧对黑碳的贡献，发现生物质燃烧广泛存在于珠三角这个高度城市化区域；3）通过比对黑碳的同位素溯源结果与“自下而上”排放清单，发现生物质燃烧的黑碳普遍被目前的排放清单低估。总体上，我们的研究对深度认识大气环境黑碳来源以及为后续排放清单的改进具有重要的意义。