中国东北区域本底大气中酸性气体的研究

Study on acidic gases in the regional background air in northeastern China

龙凤山是我国区域本底站之一，ＮＯＸ和ＳＯ２浓度远低于我国空气质量Ⅰ级标准。从１９９４年８月１５日到１９９５年７月３１日首次在龙凤山（１２７°３６′Ｅ，４４°４４′Ｎ，３３０．５ｍ）测得空气中ＮＯＸ和ＳＯ２。观测到很强的季节变化，其夏季值最低，冬季值最高。ＮＯＸ和ＳＯ２浓度和气象要素密切相关，例如风速、温度和相对湿度。基于排放源以及风频的不均一，不同扇区来的空气质量能有很大变化。在ＳＳＥ－ＳＷ扇区出现高浓度ＳＯ２、较高浓度ＮＯＸ和高〔ＳＯ２〕／〔ＮＯＸ〕，表明该扇区有城市污染物的输送。ＳＷ－ＮＮＥ扇区有高ＮＯＸ、低ＳＯ２及低的〔ＳＯ２〕／〔ＮＯＸ〕，表明该方向城市烟羽难以直接影响测点，在这个扇区高ＮＯＸ来源于当地农民做饭、取暖时秸杆焚烧。低ＮＯＸ、ＳＯ２观测在ＮＮＥ－ＳＳＥ扇区，这意味着这是最清洁扇区。

From August 15,1994 to July 31,1995,in situ measurements of NO X and SO 2 in the surface air were conducted first time at Longfengshan(127°36′E,44°44′N,330.5m a.s.l),one of the GAW′s regional station in China.Data show that the NO X and SO 2 levels were much lower than those of the Class Ⅰ in the China National Air Quality Criteria.In spite of the low concentrations of both gases,very strong seasonal variations were observed,with the lowest points in summer and the highest points in winter.The concentrations of both gases were found to be closely related to the meteorological parameters,such as wind speed,temperature and relative humidity.Due to the uneven distributions of both the emission sources and the wind frequency,air quality from different wind sectors could be very variable.The highest SO 2 and NO X levels and the maximal SO 2 / NO X ratio in the sector SSE SW indicate the traspotation of the urban pollutants from the cities in this sector.Air intermittently coming from the sector SW NNE contains highest NO X and lower SO 2.Analyses show that the urban plumes from the cities in the sector can hardly be carried directly to the site because of the unfavorable wind.The high NO X in this sector may be originated from the biomass burning during the local farmers′ cooking and heating in the sector.Very low concentratoins of NO X and SO 2 were observed when the air was ocassionally from the sector NNE SSE.It implies that NNE SSE is the cleanest sector.