基于催化加氢的碳质气溶胶黑碳和有机碳同位素定量源解析

Carbonaceous aerosol is now of worldwide concern in the field of climate and environment for its direct and indirect effects on climate change, environmental pollution, the global carbon cycle and the health risks. Carbonaceous aerosols are divided into organic carbon and black carbon, mainly from biomass burning and fossil fuel combustion.One key outstanding question with respect to BC is the apportionment of its sources between fossil fuel and biomass combustion. Radiocarbon analysis is a powerful tool, which allows to quantitatively apportion between combusion products derived form fossil fuels (14C free or "dead") and those formed from combustion of modern biomass (contemporaty levles of 14C; "alive"). For the lack of effective pre-treatment technique in separating organic carbon and black carbon of radiocarbon analysis, the aim of the project is to evaluate the hydrogen pyrolysis (hypy) as a new rapid and robust tool for the quantification and isolation of BC for radiocarbon analysis. The hypy technique will be tested using a selection of urban dust standard, biomass and coal combustion aerosol, vehicle emissions, and airborne fine particulate matter (PM2.5) in the Pearl River Delta (PRD), and the results will be compared with thermal-optical (OC/EC) measurements. On this basis, the temporal and spatial distribution of airborne fine particulate matter (PM2.5)in PRD will be revealed, the potentail sources of carbonaceous aerosols will be quantitatively apportioned, the controlling factors on the temporal and spatial variation of carbonaceous aerosols will be illustrated. Finally, the results of this project will be a scientific basis and theoretical support for the development of air pollution control countermeasures.

碳质气溶胶是当今气候与环境领域共同关注的热点，涉及到气候变化、环境影响、碳循环和健康危害等诸多问题。碳质气溶胶分为有机碳和黑碳，主要来源于生物质燃烧和化石燃料燃烧。科学判别碳质气溶胶的来源是提出碳排放消减措施的依据。通过测定碳质气溶胶黑碳中放射性碳同位素（14C）的活度是区别生物质燃烧和化石燃料燃烧来源碳质气溶胶的有效手段。针对目前在碳质气溶胶14C预处理中缺少同时有效分离有机碳和黑碳的技术手段，本项目以大气污染较为突出的珠江三角洲为研究区，通过对不同燃烧特征的样品在不同分析方法下的结果对比，建立基于催化加氢法的碳质气溶胶放射性碳同位素预处理的新方法。在此基础上,揭示珠江三角洲灰霾期和非灰霾期大气细颗粒物中碳质气溶胶的时空分布特征，定量解析碳质气溶胶的污染来源，探讨该区大气细颗粒物中碳质气溶胶时空变化的影响因素，为制定大气污染防治对策提供科学依据和理论支持。

碳质气溶胶是当今气候与环境领域共同关注的热点，涉及到气候变化、环境影响、碳循环和健康危害等诸多问题。碳质气溶胶分为有机碳和黑碳，主要来源于生物质燃烧和化石燃料燃烧。科学判别碳质气溶胶的来源是提出碳排放消减措施的依据。通过测定碳质气溶胶黑碳中放射性碳同位素（14C）的活度是区别生物质燃烧和化石燃料燃烧来源碳质气溶胶的有效手段。针对目前在碳质气溶胶14C预处理中缺少同时有效分离有机碳和黑碳的技术手段，本项目以建立基于催化加氢法的碳质气溶胶放射性碳同位素预处理的新方法。在此基础上,揭示珠江三角洲灰霾期和非灰霾期大气细颗粒物中碳质气溶胶的来源特征。主要成果包括：（1）利用催化加氢技术测定了不同燃烧来源样品的有机碳和元素碳分离特征；（2）催化加氢法分离气溶胶标准品（1649b）中有机碳和元素碳，并对其14C同位素测定，与其他方法对比；指出在150bar的氢气保护下，550℃下可完全分离有机碳和元素碳；（3）利用催化加氢技术分离广州市区冬季灰霾期与非灰霾期碳质气溶胶中的有机碳和元素碳，并对其14C同位素进行测定，获得不同时期碳质气溶胶中不同形态碳的来源特征，指出广州冬季大气中区域背景中碳质气溶胶中61%来源于现代碳，而39%来源于化石燃料，灰霾形成有两种原因，一是以化石燃料为主的一次污染物的累积，二是以现代生物质为主的一次和二次污染物的增加的结果，该结果将为制定大气污染防治对策提供科学依据和理论支持。.课题计划发布SCI论文1-2篇，目前已在Environmental Science & Technology上发表论文1篇，尚有多篇处于准备和投稿中。依托课题研究，正在培养博士研究生2名。