Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

Size-resolved biogenic secondary organic aerosols(BSOA) derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau(a continental background site) and five cities of China were measured using gas chromatography/mass spectrometry(GC/MS). Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations(R2= 0.44–0.90) between BSOA and sulfate were found at the six sites,suggesting that anthropogenic pollution(i.e., sulfate) could enhance SOA formation,because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode( 3.3 μm) except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse( 3.3 μm) modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.     

碳量子点掺杂氮化碳提高的光电化学阴极保护性能研究

目的研究g-C_3N_4/C-Dots-M复合材料的光电化学阴极保护性能。方法采用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外可见漫反射光谱技术对样品的晶体结构、微观形貌和光吸收性能进行表征。通过电化学测试可见光照射下g-C_3N_4/C-Dots-M复合材料光电极偶联316L不锈钢后的光电化学阴极保护电流密度和电位变化曲线,研究材料的光电化学阴极保护性能。结果可见光照射下,该偶联体系的光致混合电位下降至-0.43 V(vs. Ag/AgCl),光电化学阴极保护电流密度达到4.3μA/cm。结论得益于碳量子点优异的电子传导特性,g-C_3N_4/C-Dots-550复合材料的光电化学阴极保护性能比纯g-C_3N_4的明显增强。该复合材料在光电化学阴极保护方面展现了较大的应用潜力。     

硫酸盐还原菌对EH40焊接钢海水腐蚀的影响

目的研究无菌和SRB体系中EH40钢焊接接头的母材区、热影响区和焊缝区腐蚀差异。方法利用金相显微镜观察、失重法、电化学测试、扫描电镜和X射线光电子能谱仪等分析手段。结果焊缝区微观组织由块状铁素体(BLF)和魏氏组织(W)组成;热影响区可再分为粗晶区(CGHAZ)和细晶区(FGHAZ)两个区;母材区主要由BLF、AF和少量珠光体组成。在无菌对照体系中,焊缝区腐蚀速率为0.0026 mm/a,混合区次之,为0.0023 mm/a,母材区最小,为0.0019 mm/a。含SRB体系中,各区的腐蚀速率为:焊缝区(0.0037 mm/a)混合区(0.0034 mm/a)母材区(0.0030 mm/a)。热影响区腐蚀产物形貌粗大,点蚀孔也较大。结论焊缝区比母材区容易腐蚀,由此易造成小阳极大阴极加速腐蚀,热影响区容易发生点蚀。SRB能促进三个区域试样腐蚀加速。     

DZ125合金HY3包覆型涂层退除研究

目的 研究化学法退除DZ125合金HY3包覆型涂层。方法 采用真空电弧镀技术（AIP）在定向凝固镍基高温合金DZ125上制备包覆型涂层HY3,利用化学方法完全退除基体上的涂层,通过失重法研究对比1#和2#退除溶液退除HY3涂层和DZ125合金的退除速率,采用扫描电镜（SEM）对退除后的HY3涂层和DZ125基体的微观组织进行观察。结果 经过100 min,2#溶液可以将20 ?m左右的HY3涂层完全退除,采用1#溶液需要超过100 min才能完全退除涂层。两种对DZ125合金的腐蚀性很小,对于同一种合金而言,1#溶液和2#溶液对合金的腐蚀速率比值为1︰13。在1#溶液中,合金与涂层腐蚀速率的比值为1︰87.65;在2#退除溶液中,合金与涂层腐蚀速率的比值为1︰6.81。结论 1#溶液更加适合退除DZ125合金上的HY3涂层。     

兰州地区大气臭氧时空变化及影响因素研究

本文采用OMI臭氧遥感数据,结合甲醛垂直柱浓度、气象数据以及经济数据,分析了2005~2015年兰州地区臭氧柱浓度时空变化格局,并探索了影响臭氧的新气象因子,总结达到臭氧污染的日照、气压等气象条件,确定影响臭氧柱浓度的主要人为源并确定其限域。结果表明:1)2005~2015年夏季柱浓度值最高,冬季、秋季次之,春季最低;夏季波动幅度最大,其余三季波动幅度较小且平稳。2)11年中,臭氧柱浓度具有较大的波动。2005年至2010年快速增长到最高值331.997 DU。2010年之后,臭氧柱浓度缓慢下降,2014年起有回升趋势。3)OMI遥感数据具有较高的可靠性,并根据AQI的线性关系划分了臭氧柱浓度的污染等级。结果指示了11年大气臭氧空间变化,2005~2009年5年间研究区全区空气质量一直处于良,2010年全区轻度污染,后两年污染逐渐减弱,2013~2015年全区恢复至良。4)根据兰州发展的趋势以及周边城市的关系,划分了兰州经济圈及功能区,并结合臭氧柱浓度空间分布图得出臭氧污染与经济特征的密切关系。5)正弦模型拟合后臭氧柱浓度变化趋势呈不明显的周期性,说明臭氧的人为来源贡献较大。6)创新探索影响臭氧污染的新气象因子(日照、气压等参数),并确定其重要人为源限域。     

Monitoring Air Quality in Mountains: Designing an Effective Network

A quantitatively robust yet parsimonious air-quality monitoring network in mountainous regions requires special attention to relevant spatial and temporal scales of measurement and inference. The design of monitoring networks should focus on the objectives required by public agencies, namely: 1) determine if some threshold has been exceeded (e.g., for regulatory purposes), and 2) identify spatial patterns and temporal trends (e.g., to protect natural resources). A short-term, multi-scale assessment to quantify spatial variability in air quality is a valuable asset in designing a network, in conjunction with an evaluation of existing data and simulation-model output. A recent assessment in Washington state (USA) quantified spatial variability in tropospheric ozone distribution ranging from a single watershed to the western third of the state. Spatial and temporal coherence in ozone exposure modified by predictable elevational relationships ( 1.3 ppbv ozone per 100 m elevation gain) extends from urban areas to the crest of the Cascade Range. This suggests that a sparse network of permanent analyzers is sufficient at all spatial scales, with the option of periodic intensive measurements to validate network design. It is imperative that agencies cooperate in the design of monitoring networks in mountainous regions to optimize data collection and financial efficiencies.     

Cumulative impact assessment in environmental planning: A coastal wetland watershed example

Several theoretical, analytical, and institutional difficulties have impeded the development and application of the assessment of cumulative environmental impacts. Watershed development on coastal wetlands offers an ideal context for evaluating the land disturbance target approach to cumulative impact assessment. A model land use planning system involving a time series approach was developed for Elkhorn Slough in California. The approach included four major components: evaluation of erosion susceptibility, measurement of land disturbance, establishment of a land disturbance target, and a comparison of existing and target land disturbance values. Further research is needed to test the transferability of the approach in a wide range of coastal watersheds and to verify the applicability of the methods to other cumulative impact problems.     

苏州河氨化菌分布及生理生化研究

对苏州河氨化菌进行了生态调查,并对其进行了生理生化分析。研究结果表明,苏州河水体中氨化菌数量普遍较高,上游至下游氨化菌数量逐步增多。氨化菌数量与水体中总氮和氨氮呈正比,与硝酸盐成反比。     

离子色谱分析中的几个问题探讨

在掌握离子色谱技术最新发展动态的基础上,对离子色谱的新进展、前处理新技术、常用的改善分离度方法、若干注意事项、常遇到的问题等进行了分析探讨,以期用离子色谱技术更多更好地解决实际问题.     

水中Mg~(2+)的测试管快速测定

研制了一种测定水中Mg2 + 的测试管 ,测定范围为 0 .5mg/L～ 2 .0mg/L。该测试管适用于现场应急监测 ,具有快速、简便、抗干扰能力强和价格低廉等特点