Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain ...Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters （PMzs） from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon （EC） and organic carbon （OC） was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum （GC-MS）. Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. 13-Sitostrol also made up relatively a large fraction of PMz5 compared with the other sterols （0.18%-0.63% of the total fine particle mass）. Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index （CPI） of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.展开更多
用物理与化学相结合的方法研究了2个污染土壤剖面中有机质结合重金属(Cd、Cu、Pb和Zn)的分布,把有机质相结合态重金属分为颗粒状有机质(POM)结合的重金属和与细土腐殖质结合的重金属.结果表明,土壤POM对重金属有明显的富集作用,其中>...用物理与化学相结合的方法研究了2个污染土壤剖面中有机质结合重金属(Cd、Cu、Pb和Zn)的分布,把有机质相结合态重金属分为颗粒状有机质(POM)结合的重金属和与细土腐殖质结合的重金属.结果表明,土壤POM对重金属有明显的富集作用,其中>2 mm POM重金属Cd、Cu、Pb和Zn的富集系数分别在1.4～3.2、2.5～2.6、2.8～3.9和3.0～3.9之间;而0.05～2 mm POM重金属Cd、Cu、Pb和Zn的富集系数分别在2.7～7.8、3.2～6.4、3.2～9.3和3.2～5.6之间,0.05～2 mm POM组分中重金属的平均富集高于>2 mm POM组分.POM中重金属的富集程度与土壤重金属的积累呈正相关.有机质结合态重金属占土壤重金属总量的比例随土壤有机质积累而增高,表土层约40%以上的重金属以有机质结合态存在.展开更多
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2001AA641060 2003AA641040)the National Basic Research Program (973) of China (No. 2002CB410801).
文摘Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters （PMzs） from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon （EC） and organic carbon （OC） was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum （GC-MS）. Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. 13-Sitostrol also made up relatively a large fraction of PMz5 compared with the other sterols （0.18%-0.63% of the total fine particle mass）. Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index （CPI） of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.
文摘用物理与化学相结合的方法研究了2个污染土壤剖面中有机质结合重金属(Cd、Cu、Pb和Zn)的分布,把有机质相结合态重金属分为颗粒状有机质(POM)结合的重金属和与细土腐殖质结合的重金属.结果表明,土壤POM对重金属有明显的富集作用,其中>2 mm POM重金属Cd、Cu、Pb和Zn的富集系数分别在1.4～3.2、2.5～2.6、2.8～3.9和3.0～3.9之间;而0.05～2 mm POM重金属Cd、Cu、Pb和Zn的富集系数分别在2.7～7.8、3.2～6.4、3.2～9.3和3.2～5.6之间,0.05～2 mm POM组分中重金属的平均富集高于>2 mm POM组分.POM中重金属的富集程度与土壤重金属的积累呈正相关.有机质结合态重金属占土壤重金属总量的比例随土壤有机质积累而增高,表土层约40%以上的重金属以有机质结合态存在.
