生物活性磷在氯碱总厂污水处理中的应用

为了改善氯碱总厂污水处理系统磷酸盐吸收效率不高的状况，在该系统中投加了美国PROBIOTIC SOLUTIONS公司生产的生物活性磷Super Phos。结果表明：生物活性磷能以1／8—1／10的浓度取代系统原来投加的KH2PO4。投加生物活性磷后，微生物对磷的吸收效率提高，出水总磷降低：系统的CODcr、BODs、氨氮去除效率同使用前相比不变或略有提高：二沉池中的污泥沉降性能及污泥活性提高，原生动物种群增多。因此，生物活性磷完全具有取代磷酸、磷酸盐类作为磷营养添加剂的趋势，并且表现出了其他磷酸盐类所不具有的优势。     

车库内氢气扩散和分布状态的数值模拟

为研究车库内氢气连续性泄漏的浓度分布和聚集状态,采用ICEM-CFD软件建模,利用Fluent软件对氢气连续性泄漏过程进行了模拟。通过分析监测点氢气物质的量分数、氢气分布和可燃性区域体积分数,研究了横梁及其间距(L)、自然通风、通风口面积(A)对车库内氢气的扩散和分布状态的影响。结果表明:在密闭状态下,无横梁时可燃性区域最小,L=3 m时可燃性区域最大;当A=0.5 m2时,在自然通风的作用下,车库底部氢气物质的量分数明显下降,但车库中部和上部氢气物质的量分数与密闭时相近;当A=1 m2时,虽然初始阶段氢气物质的量分数上升很快,但很快就趋于稳定,监测点氢气物质的量分数均在爆炸下限以下,此时自然通风能够消除氢气爆炸的风险。     

A spectral power analysis of driving behavior changes during the transition from nondistraction to distraction

Objective: This article investigated and compared frequency domain and time domain characteristics of drivers' behaviors before and after the start of distracted driving.

Method: Data from an existing naturalistic driving study were used. Fast Fourier transform (FFT) was applied for the frequency domain analysis to explore drivers' behavior pattern changes between nondistracted (prestarting of visual–manual task) and distracted (poststarting of visual–manual task) driving periods. Average relative spectral power in a low frequency range (0–0.5 Hz) and the standard deviation in a 10-s time window of vehicle control variables (i.e., lane offset, yaw rate, and acceleration) were calculated and further compared. Sensitivity analyses were also applied to examine the reliability of the time and frequency domain analyses.

Results: Results of the mixed model analyses from the time and frequency domain analyses all showed significant degradation in lateral control performance after engaging in visual–manual tasks while driving. Results of the sensitivity analyses suggested that the frequency domain analysis was less sensitive to the frequency bandwidth, whereas the time domain analysis was more sensitive to the time intervals selected for variation calculations. Different time interval selections can result in significantly different standard deviation values, whereas average spectral power analysis on yaw rate in both low and high frequency bandwidths showed consistent results, that higher variation values were observed during distracted driving when compared to nondistracted driving.

Conclusions: This study suggests that driver state detection needs to consider the behavior changes during the prestarting periods, instead of only focusing on periods with physical presence of distraction, such as cell phone use. Lateral control measures can be a better indicator of distraction detection than longitudinal controls. In addition, frequency domain analyses proved to be a more robust and consistent method in assessing driving performance compared to time domain analyses.     

潮白河中游沉积物中重金属分布、来源及生态风险评估

潮白河是海河五大支流之一,其中游位于河北省,地处北京市下游和天津市上游,非汛期来水主要为北京市工业废水和生活污水.为了解潮白河中游沉积物重金属污染分布特征、来源、生态风险及可能受北京市来水的影响,于2018年6月采集9个表层沉积物样品和2个柱状沉积物样品,使用电感耦合等离子质谱仪（ICP-MS）测定Cr、Ni、Cu、Zn、As、Cd和Pb等7种重金属的质量分数.结果表明:①潮白河中游表层沉积物中w（Cr）、w（Ni）、w（Cu）、w（Zn）、w（As）、w（Cd）、w（Pb）的平均值分别为31.47、14.74、14.73、44.80、4.91、0.23、17.98 mg/kg,7种重金属质量分数除在5号采样点突然增加外,均沿河流方向呈先降后升的趋势.在垂直方向上,7种重金属在5号采样点出现富集,在9号采样点其质量分数则呈减轻趋势.②通过相关性分析和主成分分析可知,潮白河中游沉积物中Cr、Ni、Cu、As、Pb主要来源于工业和交通污染;Zn和Cd则主要来源于农业面源和生活污染.③地累积指数评价和潜在生态风险指数显示,潮白河中游表层沉积物重金属污染主要以Cd、Pb、Cu和As为主,其中Cd的潜在危害最高,各采样点综合潜在生态风险指数大小依次为5号> 2号> 3号> 9号> 1号> 8号> 4号> 7号> 6号.研究显示,潮白河中游沉积物重金属污染在5号采样点最严重,其中Cd污染程度最高,其来源主要为区域农业生产和居民生活等人类活动,应加强区域内农业和生活污染防治.      

我国海洋塑料垃圾和微塑料排放现状及对策

当前海洋塑料和微塑料污染问题是全球研究热点,随着我国陆源垃圾减量化处置率和生活污水处理覆盖率的提高,重新核算我国海洋塑料垃圾和微塑料排放量尤为重要,基于文献已报道的关于海洋塑料垃圾和微塑料排放量估算的方法并结合相关统计数据对我国相应排放量进行了核算.结果表明:2016年我国向海洋中排放塑料垃圾124×104~331×104 t,略低于2010年的132×104~353×104 t;生活污水处理厂向环境中排放塑料微珠约109.95×1012粒（折合131.78 t）,远低于2014年报道的209.7×1012粒（折合306.9 t）.此外,2016年我国生活污水处理厂向环境中排放合成化学纤维类微塑料约1 296.95×1012个（折合648.48 t）,轮胎与地面摩擦产生合成橡胶轮胎粉尘约78.85×104 t;合成化纤类微塑料和合成橡胶轮胎粉尘等已成为陆源微塑料的重要来源.通过与发达国家和地区在海洋垃圾和微塑料污染、陆源垃圾处置、海洋垃圾污染应对等方面进行比较,未来我国应通过完善"限塑令"和生活垃圾分类体系、尽早实施"塑料微珠"限令、明晰生活污水处理厂微塑料排放状况等手段从源头控制排放,此外需有效控制塑料垃圾和微塑料的输送途径,制定和完善相关法律法规和监测标准,提升我国应对海洋塑料垃圾和微塑料污染的能力和国际影响力.      

中石化江苏成品油一次配送空间格局与优化

基于详实准确的政府及企业调研数据,以中石化江苏成品油一次配送为例,从配置效益和空间结构视角出发,借助运用地理网络分析和线性优化模型等方法,通过单位输油成本计算、优化情景构建计算和成品油配送格局比较分析,系统解析成品油一次配送空间格局与优化配置情况,从理论上尝试探讨其地理网络结构。研究发现：优化情境下的成本较2017年实际状况减少了30%左右,表明中石化江苏成品油一次配送效益不够优化;理论上,根据成品油“就近配置”原则,不同炼油企业各自在其优化情景区界内,配送单位输油成本较低的成品油;实际上,由于炼油企业的炼油能力差异、成品油输油通道不完善和分销中心油库设置差异等原因,不同炼油企业之间存在着相较优化情景区界或大或小的实际输油区界,且存在着某些分销中心油库同时接纳不同炼油企业成品油的现象,即存在混合输油区域。     

太湖流域湖荡湿地水生植物的分布特征

2018年在太湖流域内的87个湖荡湿地调查中共发现64种水生植物,隶属于33科51属.总体来看,太湖流域水生植物种类、数量以及覆盖面积与历史上比较呈下降趋势.根据流域上不同地理区域分区（东、西、南、北4个）,分析太湖流域水生植物的分类和功能多样性,发现太湖流域四个区域的分类α多样性指数分别为4.33、5.58、5.01和3.46, β多样性指数分别为3.46、4.23、1.63和7.02,且北部和西部、北部和南部、东部和西部、东部和南部、西部和南部湖荡湿地的分类α多样性均有显著差异,同时太湖流域北部和东部、北部和西部、北部和南部、西部和南部湖荡湿地间的分类β多样性有显著差异.功能多样性方面,四个区域的β多样性指数分别为0.18、0.14、0.09、0.30,太湖流域各分区部分之间水生植物的功能β多样性均有显著差异.CCA结果表明环境变量对太湖流域湖荡水生植物组成的解释度为21.21%,水体总氮和总磷贡献最大,水体富营养化可能是影响太湖流域水生植物衰退的一个重要原因.     

某酸性矿山排水中溶解性有机物的特征分析

采集安徽某酸性矿山排水（AMD）水库不同离岸距离的表水层水样,结合傅立叶变换离子回旋共振质谱（FT-ICR MS）与三维荧光光谱（EEMs）技术对水样中溶解性有机物（DOM）来源和组分特征进行分析.三维荧光结果表明,样品中内源性色氨酸类荧光峰峰强与离岸距离正相关,且基于三维荧光特征指数（FI,HIX,BIX）分析判断DOM主要来自于内源.FT-ICR MS在分子层面进一步表明,内源性组分（脂类,脂肪族/蛋白类,糖类）在近岸点样品DOM所占比重相对较低（66%）.AMD中DOM的主要成分为CHO（40%~50%）、CHON（25%~30%）、CHOS （22%~36%）等化合物.DOM包含有高比例的CHOS化合物主要与AMD水体高浓度硫酸盐有关.     

Adsorption mechanisms of PFOA onto activated carbon anchored with quaternary ammonium/epoxide-forming compounds: A combination of experiment and model studies

When wood-based activated carbon was tailored with quaternary ammonium/epoxide (QAE) forming compounds (QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid (PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before half-breakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.     

Characterization of VOC emissions from construction machinery and river ships in the Pearl River Delta of China

Speciated characterization of Volatile Organic Compounds (VOCs), including oxygenated VOCs (OVOCs), from construction machinery and river ships in China is currently lacking. In this regard, we conducted field measurement on speciated VOC (including OVOC) emissions from six construction machinery and five river ships in the Pearl River Delta (PRD) region to identify VOC emission characteristics. We noticed that OVOC emissions from construction machinery and ships accounted for more than 50% of the total VOC emissions, followed by alkenes, aromatics and alkanes. Formaldehyde and acetaldehyde were the most emission species, accounting for 61.8%-83.2% of OVOCs. For construction machinery, the fuel-based emission factors of roller, grader and pile driver were 3.12, 3.12 and 7.36 g/kg, respectively. With the rigorous restraint by the national emission standards, VOC emissions of construction machinery had decreased considerably, especially during stage Ⅲ. Ozone formation potential was also significantly reduced due to the significant decrease in emissions of OVOCs and alkenes with higher reactivity. For river ships, the fuel-based emission factors of cargo ships and speedboat were 1.46 and 0.44 g/kg, respectively. VOC emissions from construction machinery and river ships in Guangdong Province in 2017 were 8851.0 and 4361.0 ton, respectively. This study filled the knowledge gaps of reactive gas emissions from different kinds of non-road mobile sources over the PRD, and more importantly, highlighted the necessity in adding OVOC measurement to give a complete and accurate depiction of reactive gas emissions from non-road mobile sources.