近50年春季沙尘活动及其对PM_(10)质量浓度的影响

利用中国北方847个地面气象台站观测的天气现象,从沙尘日数的时空分布、变化趋势等方面对1961 2012年中国北方春季沙尘活动进行了分析。结果表明,中国西北部的沙漠地带是春季沙尘暴和扬沙的多发和频发区。除个别台站,绝大部分北方站点的沙尘暴日数、起沙日数均呈显著下降趋势。1961 2012年中国北方区域平均的春季沙尘暴日数、起沙日数变化趋势分别为-1.2 d·(10a)-1和-2.3 d·(10a)-1,下降趋势显著。另外,沙尘暴的影响范围也逐步缩小。通过分析大气环境监测的PM10质量浓度(ρPM10)日平均值数据表明,发生沙尘时,北京、石家庄、济南、兰州、西宁的日空气质量易超标。ρPM10日平均值与沙尘持续时间呈显著正相关,即沙尘持续时间越长,ρPM10日平均值增幅越大。     

高岭土中全硫量快速测定方法

采用碳酸钠一氧化镁半熔融一氯化钡滴定法测定高岭土中的硫含量。试样用碱性熔荆半熔，熔块以水浸取，将转化为硫酸盐后的滤液，以玫瑰红酸钠为指示剂，在pH为5．5．7．0的条件下，用氯化钡标准溶液进行滴定。测定结果的RSD=2．47％（n=5），加标回收率为95．2％-100．3％。改进后的方法已用于高岭土中全硫量的测定，结果与国标重量法相符。     

Intercomparison of NO_x, SO_2, O_3, and Aromatic Hydrocarbons Measured by a Commercial DOAS System and Traditional Point Monitoring Techniques

A field-based Intercomparison study of a commercial Differential Optical Absorption Spectroscopy (DOAS) instrument (OPSIS AB, Sweden) and different point-sample monitoring techniques (PM, based on an air monitoring station, an air monitoring vehicle, and various chemical methods) was conducted in Beijing from October 1999 to January 2000. The mixing ratios of six trace gases including NO, NO2, SO2, O3, benzene, and toluene were monitored continuously during the four months. A good agreement between the DOAS and PM data was found for NO2 and SO2. However, the concentrations of benzene, toluene, and NO obtained by DOAS were significantly lower than those measured by the point monitors. The ozone levels monitored by the DOAS were generally higher than those measured by point monitors. These results may be attributed to a strong vertical gradient of the NO-O3-NO2 system and of the aromatics at the measurement site. Since the exact data evaluation algorithm is not revealed by the manufacturer of the DOAS sys     

泡沫铝填充方钢管压弯构件滞回性能的试验研究

通过6根泡沫铝填充方钢管构件和3根方钢管构件进行的低周反复荷载试验,分析了填充泡沫铝对方钢管构件滞回性能的影响,以及泡沫铝材料的相对密度、孔径对构件滞回性能的影响。试验结果分析表明,试件荷载-位移滞回曲线的图形饱满,没有明显的捏缩现象出现;填充泡沫铝后,钢管的滞回曲线比空钢管的更饱满,滞回性能得到了提高,抗震性能良好。