西安市某工业园夏季VOCs浓度特征及O3、SOA生成潜势

2020年7月30日—10月10日对西安市某工业园区大气中的70种VOCs开展了为期73 d的VOCs手工采样监测,分析了上、下风向2个点位VOCs浓度组成特征、O₃生成潜势和SOA生成潜势,并运用PMF进一步分析该区域VOCs的主要来源。结果显示：监测期间工业园区平均VOCs浓度为203.50 μg/m³,以甲醛和乙醛为主的醛酮类（148.37 μg/m³）是主要污染物,占TVOC浓度的57%~84%,其次是烷烃。通过上、下风向VOCs成分比较发现,醛酮类为高污染时段特征污染物,工业园区平均OFP为969.66 μg/m³,醛酮类对O₃生成的贡献最大,占TOFP的80%~97%,其次是烯烃。工业园区平均SOAFP为0.50 μg/m³,芳香烃对SOA生成的贡献最大,占TSOAFP的48%~98%,其次是烷烃。PMF源解析得到5个因子,分别为工业源、溶剂涂料、燃烧源、移动源及其他源,贡献率分别占35.2%、20.4%、18.3%、12.8%、13.3%,解析显示该区域受到下风向电子产业影响较大。     

城市污水处理厂缺氧池短程反硝化现象及影响因素研究

调研了北方某城市污水处理厂缺氧池亚硝态氮积累的现象.该污水处理厂采用传统厌氧/缺氧/好氧（A/A/O）工艺,在缺氧池中存在稳定的短程反硝化过程,且缺氧池中亚硝态氮积累率最高可达88.4%.16S rRNA高通量测序分析表明Saccharibacteria_genera_incertae_sedis和Thauera可能是导致该厂缺氧池亚硝态氮积累的主要菌种,而短程反硝化现象出现的主要原因可能为外加碳源乙酸钠和系统较高的pH值.取活性污泥在COD/NO₃^--N为2~5条件下进行反硝化批次试验,结果表明硝态氮的还原速率均高于亚硝态氮的还原速率,且最大硝态氮到亚硝态氮的转换率均在50%左右.但碳源充足时,积累的NO₂^-会在NO₃^-被还原完后继续发生还原反应,从而导致最终亚硝态氮积累效果变差.本研究,以乙酸钠为碳源,COD/NO₃^--N为3可使反硝化过程获得最高亚硝态氮积累.因此,控制合适COD/NO₃^--N或缺氧反应时间是短程反硝化工艺运行的关键控制参数.本研究可为实际污水处理厂构建短程反硝化并进一步耦合厌氧氨氧化技术提供参考.     

<Emphasis Type="Italic">A Posteriori</Emphasis> Evaluation of Strategies of Management: The Effectiveness of No-Wash Zones in Minimizing the Impacts of Boat-Wash on Macrobenthic Infauna

Wind-driven waves are important in structuring intertidal and shallow subtidal assemblages of macrobenthic infauna. In the sheltered waters of estuaries, boat-generated waves (wash) may play a similar role because they are typically of a similar amplitude or larger than wind-driven waves. However, few studies have attempted to determine the role of wash in structuring assemblages. Consequently, strategies for managing boating focus around minimization of bank erosion. Along the Parramatta River (Sydney, Australia), no-wash zones have been established and mangroves planted to minimize the erosion of riverbanks and collapse of seawalls purportedly caused by 35-m-long RiverCat ferries. Although intended to also reduce the ecological impacts of wash, it is unclear whether these strategies achieve this goal. Unvegetated and vegetated (among the pneumatophores of mangroves) sediments were sampled in wash and no-wash zones along the Parramatta River to assess the effectiveness of no-wash zones and vegetation of river banks in reducing the ecological impacts of wash. Specifically, it was hypothesized that (1) assemblages of intertidal macrobenthic infauna would differ between wash and no-wash zones of the Parramatta River and (2) these differences would be greater in unvegetated than in vegetated habitat. As predicted, assemblages of macrobenthic infauna differed between the wash and no-wash zones. Capitellids, nereids, and spionids were more abundant in the no-wash zone. Contrary to the hypothesis, differences were no greater in the unvegetated habitat than in the vegetated habitat. The results suggest an impact of wash on assemblages of macrobenthic infauana and a role for no-wash zones in minimizing the effects of this disturbance.     

Hydrochemical Buffer Assessment in Agricultural Landscapes: From Local to Catchment Scale

Non-point-source pollution of surface and groundwater is a prominent environmental issue in rural catchments, with major consequences on water supply and aquatic ecosystem quality. Among surface-water protection measures, environmental or landscape management policies support the implementation and the management of buffer zones. Although a great number of studies have focused on buffer zones, quantification of the buffer effect is still a recurring question.The purpose of this article is a critical review of the assessment of buffer-zone functioning. Our objective is to provide land planners and managers with a set of variables to assess the limits and possibilities for quantifying buffer impact at the catchment scale. We first consider the scale of the local landscape feature. The most commonly used empirical method for assessing buffers is to calculate water/nutrient budgets from inflow–outflow monitoring at the level of landscape structures. We show that several other parameters apart from mean depletion of flux can be used to describe buffer functions. Such parameters include variability, with major implication for water management. We develop a theoretical framework to clarify the assessment of the buffer effect and propose a systematic analysis taking account of temporal variability. Second, we review the current assessment of buffer effects at the catchment scale according to the theoretical framework established at the local scale. Finally, we stress the limits of direct empirical assessment at the catchment scale and, in particular, we emphasize the hierarchy in hydrological processes involved at the catchment scale: The landscape feature function is constrained by other factors (climate and geology) that are of importance at a broader spatial and temporal scale.Published on line     

Probabilistic indicators of atmospheric transport for regional monitoring and emergency preparedness systems

In this paper, following a methodology developed within the "Arctic Risk" Project of the Nordic Arctic Research Programme, several probabilistic indicators to evaluate the risk site possible impact on the geographical regions, territories, countries, counties, cities, etc., due to atmospheric transport from the risk site region were suggested. These indicators-maximum possible impact zone, maximum reaching distance, and typical transport time-were constructed by applying statistical methods and using a dataset of isentropic trajectories originated over the selected nuclear risk site (Ignalina nuclear power plant, Lithuania) during 1991-1996. For this site, the areas enclosed by isolines of the maximum possible impact zone and maximum reaching distance indicators are equal to 42 x 10(4) and 703 x 10(4) km(2), respectively. The maximum possible impact zone's boundaries are more extended in the southeast sector from the site and include, in particular, Latvia, Lithuania, Belarus, and several western regions of Russia. The maximum reaching distance's boundaries are twice more extended in the eastern direction from the site (reaching the Caspian Sea) compared with the western direction. The typical transport time to reach the southern territories of Sweden and Finland, northern regions of Ukraine, and northeast of Poland is 1 day. During this time, the atmospheric transport could typically occur over the Baltic States, Belarus, and western border regions of Russia, and central aquatoria of the Baltic Sea. Detailed analysis of temporal patterns for these indicators showed importance of the seasonal variability.     

油罐火灾沸溢发生时间预测模型

油罐火灾发生沸溢具有很大的危险性,而沸溢时间的准确预测是目前的一个技术难题。笔者结合宽沸程油品油罐火灾沸溢实验,对油层内部传热过程进行详细分析,认为油罐火灾沸溢事故可近似地看作一无内热源、常物性的非稳态传热问题,其过程包含油水界面不参与换热和参与换热的两个阶段。建立了油罐火灾沸溢发生时间预测模型,对两个不同阶段,分别进行理论分析和数值方法进行求解,并同实验数据对比。结论可信,误差较小,为沸溢机理探讨研究和油罐沸溢火灾的扑救提供了参考依据。计算表明:燃烧速度和油罐底部水层厚度对沸溢时间的影响很大,而降低罐壁温度并不能有效地延迟沸溢的发生。     

马家沟矿煤与瓦斯动力现象机理研究

马家沟矿煤与瓦斯动力现象严重威胁着该矿的安全生产,掌握其机理意义重大。笔者在统计并分析该矿煤与瓦斯动力现象的基础上,以上山掘进和石门揭煤为例,根据煤与瓦斯动力现象发生后遗留的典型孔洞形状,采用RFPA-Flow对其进行数值模拟。通过数值模拟反演出了该矿动力现象发生的地质条件及过程,得出了马家沟矿煤与瓦斯动力现象机理,并通过数据处理,得出了在动力现象前后掘进头前方煤体内地应力、瓦斯压力分布状况及卸压区宽度变化规律。     

氮肥厂环境评价中卫生防护距离的确定

在氮肥厂环境评价中,确定卫生防护距离是非常必要的,而相关的研究、介绍却较少.通过实例分析,介绍了氮肥厂卫生防护距离计算方法、原则和步骤,采用地面浓度反推法,计算出污染物的无组织排放量,对其中有关参数进行了取舍,从而确定出卫生防护距离,并提出了现有计算方法的不足和需要改进的方面.     

河流污染带特征参数预测模型及其软件化研究

本文建立了连续点源和瞬时点源两种常见排污工况下河流污染带的特征参数预测模型，模型预测的污染带特征参数包括污染物达到全断面均匀混合的距离、污染带最大长度、最大宽度及其出现的位置、污染带面积等，并能利用污染带的特征参数反演推算允许排污量和削减量。模型所用方法简便易行，且具有较高精度，可用于常规连续排污和突发事故排污情况下的河流污染带预测。在此基础上，研制开发了河流污染带特征参数预测系统（RPZS），方便实用。