柳州市2009-2014年空气污染变化

近年来,城市空气污染日益严重,已成为公众广泛关注的环境问题之一。柳州是中国西部的工业重镇、广西有名的工业城市,位列国家划定的113个大气污染防治重点城市之中,是广西第一个开展PM2.5监测的城市。本研究于2009—2014年连续6年对柳州市大气主要污染物SO2、NO2、PM10和PM2.5的浓度进行在线观测,获得了污染物的长期时间和空间分布特征。结果显示,SO2浓度呈逐年下降趋势,并于2011年达标之后显著下降,2014年相比2009年下降了50.0%;NO2浓度一直在低于标准以下波动(24.6~35.1μg/m3);PM10浓度呈逐年增长趋势,并从2011年开始超标,2014年相对于2009年增长了69.3%。各污染物浓度都具有显著的季节变化:冬季秋季春季夏季。SO2、NO2、PM10和PM2.5的浓度冬季相比夏季分别提高82.9%、56.3%、66.9%和133.6%。冬季SO2和秋冬季PM10超标,PM2.5除7月外全线超标。PM2.5/PM10的比值冬季也高于夏季,表明冬季更易富集细颗粒。各污染物浓度也表现出不同的空间分布。九中各污染物的浓度都最高,可能与其离柳州钢铁公司距离较近有关。SO2除九中外,其他站点均达标。NO2全部达标。PM10市监测站和九中超标。PM2.5所有站点超标严重。本研究结果表明,柳州市煤烟型污染得到有效控制,但颗粒物污染,尤其是细颗粒物污染日益严重。

Variations of Air Pollutants in Liuzhou from 2009 to 2014

In recent years, urban air pollution is increasingly serious and has become one of the environmental issues attracting wide public concern. Liuzhou is a famous industrial city in western China, a member of the 113 major cities designated by the national environment protection bureau of China and the first city in which PM_2.5 monitoring has been carried out in Guangxi province. Six-year continuous online measurements of the atmospheric main pollutants, such as SO₂, NO₂, PM₁₀ and PM_2.5 were conducted during 2009-2014 in Liuzhou, Guangxi province. The spatio-temporal patterns of the pollutants were obtained. SO₂ levels showed a downward trend, met the standard (GB3095-2012) in 2011 and plummeted since then, with a 50.0% decrease from 2009 to 2014. NO₂ levels stayed below the standard all the time, but exhibited obvious annual fluctuation. PM₁₀ levels showed a rising trend and exceeded the standard in 2011, with a 69.3% increase from 2009 to 2014. The pollutants showed consistent seasonal variations: winter > autumn > spring > summer, with growth rates of 82.9%, 56.3%, 66.9% and 133.6% from summer to winter for SO₂, NO₂ and PM₁₀, respectively. While SO₂ and PM₁₀ levels exceeded the standards in winter and fall-winter, respectively, PM_2.5 levels exceeded the standard in all seasons except in July. PM_2.5/PM₁₀ ratios were also higher in winter than in summer, reflecting heavier fine particle pollution. The pollutants also showed distinct spatial variations, but all of them exhibited highest levels in No. 9 middle school, possibly due to its adjacency to Liuzhou Iron and Steel Co., Ltd. SO₂ and NO₂ levels at all sites met the standard, except for SO₂ at No. 9 middle school. PM₁₀ levels at Liuzhou environmental monitoring station and No. 9 middle school exceeded the standard. PM_2.5 levels at all the sites seriously exceeded the standard. These results indicate that the coal-smoke pollution has been effectively controlled, while particulate air pollution, especially the fine particle pollution has become a growing problem in Liuzhou.