大气降尘测定中蒸发方式的选择

为了加快大气降尘样品的蒸发速度和报出数据的及时,经过分析总结,得出蒸发样品的步骤为:先电热套蒸发再水浴蒸发最后用电热板蒸发,这样既可以节省时间,又可以节约能耗,避免样品在空气中放置时间过长,空气中的尘粒进入样品中,影响样品测定的结果。     

A Technique for Estimating the Age of Regular/Mid-grade Gasolines Released to the Subsurface Since the Early 1970's

Investigators, regulators, and litigants having interest in gasoline hydrocarbon releases are almost always concerned with knowing when a release occurred. Gasoline releases to the subsurface have, historically, been the most difficult to age date because of their volatile nature and highly aromatic composition. Age dating of gasolines in the past has depended on the degree of weathering of the lower boiling hydrocarbons in gasoline, the use and disuse of lead, lead isotopes, the use of other additives such as methyl-tertiary-butyl ether, and major refining and formulation changes. However, these approaches are limited and many times difficult to demonstrate and apply. This paper describes a new age dating technique using gas chromatographic data. It is based on the progressive enhancement of the aromatics and the reduction of the normal alkanes (paraffins) in the manufacture of regular and mid-grade gasolines since the 1970s. The changing composition of gasoline was necessary to maintain octane ratings during the removal of lead from the gasoline and while meeting increasingly stringent air quality regulations over the past 30 years. This paper proposes the use of an index that reflects these changes in gasoline composition over time and can be correlated to when the gasoline was manufactured. The resulting curve can be used to estimate the age of release (manufacture) of gasolines. This forensic application can be successfully applied to liquid gasoline samples where the evaporation of the gasoline is less than 50%. Case histories and examples are presented to demonstrate application of the technique.     

油气挥发污染控制技术探讨

油品储运过程中油气的挥发带来了严重的环境污染。利用油气回收技术作为主要的降耗措施已得到重视和推广应用。通过对储运过程中污染现状的分析及各类油气回收控制技术特点的分析,为今后的技术开发指出方向。