The primary pollutant of surface sediment is Organic matter.
表层沉积物主要污染因子为有机质；
This study suggested the primary pollutant which should be controlled was PM2.5 to increase the visibility in Beijing.
研究的结果提示提高北京地区大气能见度，需要控制的首要污染物为PM 2.5。
Analyze the main index, which include API, primary pollutant, air quality level, in 86 cities of china from Urban Ambient Air Quality Daily Report of 2006.
收集了2006年《重点城市空气质量日报》中中国86个重点城市空气质量主要分析指标——空气污染指数（A PI）、首要污染物、空气质量级别，并对数据进行统计分析。
As a result of chemical conversion and decay, the primary pollutant decreases with the downwind distance more rapidly, especially as the mesoscale distance further than 10 km.
由于化学转换和衰减的作用，初生污染物随着下风距离而较快地减少，特别是在10公里以后的中距离上更加明显；
As a result of chemical conversion and decay, the primary pollutant decreases with the downwind distance more rapidly, especially as the mesoscale distance further than 10 km.
由于化学转换和衰减的作用，初生污染物随着下风距离而较快地减少，特别是在10公里以后的中距离上更加明显；
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