太原市PM2.5浓度的气象特征影响分析及预报

利用2016～2020年太原市污染物浓度资料、以及国家基准气象观测站的同期地面气象资料,重点分析了太原市PM_2.5浓度的变化特征以及湿度、降水、风和混合层厚度等气象条件对PM_2.5浓度的影响,同时探讨了污染物浓度变化的成因,建立基于LSTM神经网络的PM_2.5浓度预报模型.结果表明,2016～2020年太原市区冬季出现的重污染天数最多,其中2017年冬季出现天数最多为28 d, PM_2.5浓度总体呈现出秋冬季节高,春夏季节低,周末PM_2.5浓度高于工作日浓度,PM_2.5浓度日变化大致呈现双峰型分布,分别出现在09:00左右和23:00至翌日01:00.除相对湿度和冬季气温外,其余气象要素与PM_2.5浓度在四季均表现为负相关.影响太原市区PM_2.5浓度升高的污染源主要位于其NE-ENE-E方向,西北部地区的相对不明显.汛期当达到中雨(降水量≥10 mm)以上级别的降水都对PM_2.5浓度降低有明...     

Occupational safety conditions of bus drivers in Metro Manila,the Philippines

The study looks into the occupational safety and working conditions among bus drivers in Metro Manila, the Philippines. Quantitative data were collected through survey interviews of 95 bus drivers using the stratified sampling technique. Results showed that bus drivers worked an average of 16?h/day and were engaged in risky driving behaviors such as over-speeding and road racing in order to reach their quota for the day. Fifty-nine percent experienced work-related accidents, with a mean of three accidents. The most common accident was hitting another vehicle followed by side swipe. The accidents were blamed on other drivers, followed by vehicle defect, inattentiveness and tiredness/micro-sleep or sudden involuntary sleep while driving. The most common health symptoms experienced by the bus drivers were fatigue, back pain, and cough and colds. This study underlines the need for an occupational health and safety program for bus drivers in the Philippines.     

长距离输煤管道储浆罐与石油储罐对比研究

对比研究长距离输煤管道储浆罐与石油储罐搅拌设计特点、罐顶设计特点、消防安全设施特点。经分析可知,长距离输煤管道储浆罐宜选用推进式搅拌器,罐壁上设置导流结构,宜采用固定顶、锥顶,设置简单消防安全设施,宜选用难燃保温材料;石油储罐优先选用旋转喷射式搅拌器,罐内油品进行定期搅拌,采用浮顶,大型的一般选用外浮顶,需设置完善消防安全设施。     

Analysis of culturable and unculturable microbial community in bensulfuron-methyl contaminated paddy soils

To investigate the influence of bensulfuron-methyl(BSM)on culturable microbial quantities and unculturable microbial community structures,conventional and molecular biological methods were employed in five BSM treated soils with three replications,respectively. The results obtained with traditional culture-dependent methods showed that a low-level of BSM had slight and transient effects on culturable microorganisms;nevertheless,high concentration of BSM resulted in a dramatic decrease in bacterial colony fo...     

Can Warmwater Streams Be Rehabilitated Using Watershed-Scale Standard Erosion Control Measures Alone?

Degradation of warmwater streams in agricultural landscapes is a pervasive problem, and reports of restoration effectiveness based on monitoring data are rare. Described is the outcome of rehabilitation of two deeply incised, unstable sand-and-gravel-bed streams. Channel networks of both watersheds were treated using standard erosion control measures, and aquatic habitats within 1-km-long reaches of each stream were further treated by addition of instream structures and planting woody vegetation on banks (“habitat rehabilitation”). Fish and their habitats were sampled semiannually during 1–2 years before rehabilitation, 3–4 years after rehabilitation, and 10–11 years after rehabilitation. Reaches with only erosion control measures located upstream from the habitat measure reaches and in similar streams in adjacent watersheds were sampled concurrently. Sediment concentrations declined steeply throughout both watersheds, with means ≥40% lower during the post-rehabilitation period than before. Physical effects of habitat rehabilitation were persistent through time, with pool habitat availability much higher in rehabilitated reaches than elsewhere. Fish community structure responded with major shifts in relative species abundance: as pool habitats increased after rehabilitation, small-bodied generalists and opportunists declined as certain piscivores and larger-bodied species such as centrarchids and catostomids increased. Reaches without habitat rehabilitation were significantly shallower, and fish populations there were similar to the rehabilitated reaches prior to treatment. These findings are applicable to incised, warmwater streams draining agricultural watersheds similar to those we studied. Rehabilitation of warmwater stream ecosystems is possible with current knowledge, but a major shift in stream corridor management strategies will be needed to reverse ongoing degradation trends. Apparently, conventional channel erosion controls without instream habitat measures are ineffective tools for ecosystem restoration in incised, warmwater streams of the Southeastern U.S., even if applied at the watershed scale and accompanied by significant reductions in suspended sediment concentration.     

长光路FTIR研究HFC152a光化学反应

用长光路ＦＴＩＲ技术研究氟里昂替代物ＨＦＣ１５２ａ（ＣＨ３ＣＨＦ２）在对流层中的化学反应，氯离子作反应的引发剂，用相对速度方法测定了ＨＦＣ１５２ａ与Ｃｌ原子反应速率常数为（２．３±０．５）×１０＾－１３ｃｍ＾３·ｍｏｌ＾－１·ｓ＾－１（２９８±Ｋ）。ＨＦＣ１５２ａ在对流层中的主要含氟光解产物为ＣＯＦ２，产率为８８％。有关反应机理进行了讨论。     

南京北郊O3、NO2和SO2浓度变化及长/近距离输送的影响

利用2008年1月—2010年12月南京北郊O₃、NO₂和SO₂质量浓度连续观测资料结合后向轨迹模式,采用聚类分析对轨迹进行分类和KZ滤波器对数据组分进行分离的方法,讨论了南京北郊气体污染物(O₃、NO₂和SO₂)的质量浓度变化规律及长/近距离输送对该地区污染气体的影响.结果表明,南京北郊春末夏初(5、6月)O₃月均浓度出现最大值,12月出现最小值;NO₂在春季(3—5月)月平均浓度相对较高,8月份浓度全年最低,而SO₂浓度在6、7月出现最低值.不同季节气体污染物浓度日变化各有特点,O₃呈单峰分布,12:00—15:00出现浓度最大值;NO₂浓度高值则出现在夜间;SO₂在清晨出现最大值,另外,春秋冬季SO₂呈双峰型分布.长/近距离输送对南京北郊污染气体影响的分析表明,在西南方向的近距离输送影响下,该地区O₃浓度将会出现明显的高值;传输速度较慢的西北气流则会促使该地区形成高浓度的NO₂;长距离输送对O₃和NO₂的贡献与气团输送距离有关,说明该地区O₃和NO₂是区域性问题.另外,当在传输速度较慢的偏东气流的控制下,SO₂的浓度较高,说明SO₂的高浓度事件与偏东方向的近距离输送有关.     

地铁深基坑变形规律参数化方法探讨

在对基坑隆起、基坑围护桩体水平变形以及基坑周边地表沉降产生机理、变形规律和影响因素分析的基础上,提出各测项的变形模式：基坑隆起为抛物线模式,围护桩体水平变形和基坑周边地表沉降为双直线模式.变形模式中的参数取值与基坑条件（包括工程、水文地质条件、岩土体物理力学性质、支护结构形式等）存在对应关系.给出了以监测数据为基础的各变形模式参数的线性回归方法,为建立以回归参数控制的预测分析库奠定基础.     

三种霾日统计方法的比较分析

为了研究单次值法、日均值法、14时值法3种常用的霾日和轻雾(雾)日统计结果的异同,以环首都圈京津冀晋四省市为例进行了比较.华北地区霾日用3种方法统计的过去60余年霾日的区域分布表明,3种方法统计的霾日是单次值法>日均值法>14时值法,大致是1:0.54:0.45的关系,但区域分布趋势比较相似.典型城市霾日的长期变化趋势大都十分相似.而轻雾(雾)日的长期变化趋势表明,用单次值法统计的明显偏多,且有长期下降趋势;而用日均值法与14时值法统计的轻雾(雾)日无大差别,且没有明显的长期变化趋势,反映了年季和年代季的气候波动.从长期季节变化趋势来看,3种统计方法的结果除日数的差别外,季节分布特征比较类似.一个突出的特点是除去采暖季有较多的霾日外,在盛夏季节霾日也明显多,集中出现在6~9月,尤其是7~8月,与桑拿天同期出现,这与全国大部分城市的变化趋势完全不同.是华北地区的特有现象.用单次值法统计霾日,将包括所有的霾过程,即大范围持续时间长,且与一定天气系统与近地层扩散条件相关连的霾,及在稳定的晴朗夜间由于辐射降温,使相对湿度升高而导致能见度下降形成的霾.用日均值法,则可能更多的显示长时间大范围的霾天气过程;而使用14时法,则对早晚因湿度增加降低能见度出现的霾天气漏记,突出长时间大范围的霾天气过程.     

热、热碱处理对污泥溶胞和溶解性有机物的影响

污泥有机物的水解是厌氧消化过程中的限速步骤,预处理可以有效地将污泥固体有机物转化为溶解态有机物,从而提高有机物降解速率和甲烷转化速率.本文研究了热、热碱处理(两种常用的预处理方法)对污泥溶胞释放溶解性有机物的组成、相对分子质量分布和结构的影响.结果表明,热、热碱处理均能大量释放溶解性有机物,相比对照组污泥,溶解性化学需氧量可分别增加21.9倍(热处理)和47.8倍(热碱处理).两种预处理会改变溶解性有机物相对分子质量分布,且含量最多的有机物相对分子质量减小.两种预处理均对污泥溶解性有机物中的主要组分(蛋白质)有水解作用,且热碱处理效果更显著.三维荧光光谱分析表明溶出的有机物中溶解性微生物副产物类物质和胡敏酸类物质难以被两种预处理进一步水解.另外,两种预处理不仅使污泥溶解性物质中出现新的有机结构,还会使原有的有机结构发生变化,甚至消失.