Regional air pollution is complex and becomes increasingly important in China.Among many others,secondary organic aerosol(SOA) is one of the most important components of PM2.5.This paper discusses various methods for quantifying SOA in the atmosphere(including methods based on the EC tracer,WSOC,receptor model,the SOA tracers,and air quality model),presents the basic principle of each method and points out that 1) the EC-tracer method,the WSOC method and the receptor model method are relatively simple and convenient,but limited by the availability of local source profiles and some specific tracers;2) the SOA-tracer method is analytically challenging but can supply source-specific SOA information;and 3) the air quality model method can provide large scale spatial distribution of SOA.This paper also summarizes the most recent results of SOA research in China and abroad and indicates that SOA is important in organic aerosol,and anthropogenic VOCs play a significant role in SOA formation in China.The primary purpose of this review is to provide basic and integrated information and suggestion for future directions of SOA study in China.
For the first time, PM2.5 source apportionment methods and techniques previously and currently applied in China are summarized, including sampling preparation, sampler selection, chemical speciation analysis, and source apportionment tools. The research direction for PM2.5 source apportionment work in China is also suggested. This review is expected to provide a fundamental understanding of PM2.5 source apportionment methods and to serve as an important reference for future source apportionment studies to be widely conducted in China and regulations or law for PM2.5 abatement in China.
This article reviews the current research on stroke order of hanzi (as used to write the Chinese, Japanese and Korean languages) in teaching Chinese as a second language (CSL). Based on an extensive review of current research on stroke order, it first discusses the importance and difficulty of stroke order in hanzi learning. It goes on to present the mixed attitudes held by CSL learners and teachers towards learning stroke order, followed by a synthesis of the literature on stroke order errors and current methods of displaying and practising stroke order. Finally, some key implications for teaching and learning stroke order are suggested, and future research directions are proposed for the Chinese language classroom.
Durinf April, July, October 2009 and January 2010, daily (24-h average) PM2.5 sample were collected at urban sites in Beijing and 29 metal elements were analized by the ICP-MS.