A pragmatic approach for estimation of source-zone emissions at LNAPL contaminated sites

When considering natural attenuation as a remediation strategy at a site contaminated by a light non-aqueous phase liquid (LNAPL), it is important to consider the emission of contaminants from the source zone. A quantification of source-zone emissions is essential both for comparison with down-gradient mass fluxes to provide an estimate of fractional mass flux reduction, as well as for estimating the source lifetime. Because the spatial distribution of LNAPL at a field site is strongly dependent on both the spill circumstances and the heterogeneity of the geologic materials, which can be problematic for in-situ determination, alternative methods for estimating source-zone emissions are needed. In this work, a three-dimensional multiphase flow and transport modelling approach is used to investigate the relationship between the lateral extent of an LNAPL body and the emission of contaminants to groundwater at a contaminated site. For simulations involving an LNAPL release in an aquifer comprised of heterogeneous porosity and permeability distributions that were generated geostatistically, it is shown that a simple linear relationship exists between the lateral extent of the LNAPL body in the capillary fringe and the emission to the aqueous phase. The parameters describing the relationship are found to be linear functions of the groundwater flow velocity and the vertical infiltration rate. This site-specific relationship provides a simple method to estimate contaminant emissions to groundwater at LNAPL contaminated sites.     

Vertical distribution and environmental significance of sulfur and oxygen heterocyclic aromatic hydrocarbons in soil samples collected from Beijing, China

Vertical distribution of the concentration and composition of some sulfur and oxygen heterocyclic aromatic hydrocarbons (SOHAHs), such as, fluorene, dibenzofuran, dibenzothiophene and their alkyl homologues in 10 soil profiles in Beijing have been investigated. The results showed that the concentrations and composition of SOHAHs in topsoil (0-30cm) from different profiles are different. The concentrations of SOHAHs in topsoils are much higher than that in bottom soils where the concentrations are relatively constant. The fingerprints of SOHAHs from same profile are similar in topsoil samples, which are obviously different at the deep part, which suggested that the sources of these compounds are consistent in topsoil and are discriminating between surface and bottom soils. The main sources of SOHAHs in surface soil were fossil fuel combustion, petroleum and wastewater irrigation, while those at deep part were likely derived from the degradation products of soil organic matters.     

用含油污泥制备油田调剖剂

采用油田含油污泥研制了油田调剖剂（含油污泥调剖剂）,对其性能进行了评价,并进行了现场应用。综合考虑性能成本等因素,含油污泥调剖剂的最佳配方为（w）：聚丙烯酰胺0.20%,交联剂A 0.30%,稳定剂B 0.15%,含油污泥10%~20%。含油污泥调剖剂对岩心的封堵率比常规调剖剂高3.5%,且二者对岩心的封堵率均大于90%。含油污泥调剖剂现场应用5井次,累计处理含油污泥1 880 t,注水压力平均上升2 MPa,累计增油160 t,减水6 500 m3,经济创效583 000元,投入产出比为1∶1.5。     

Volatile organic compound concentrations, emission rates, and source apportionment in newly-built apartments at pre-occupancy stage

The present study investigated the indoor concentrations of selected volatile organic compounds (VOCs) and formaldehyde and their indoor emission characteristics in newly-built apartments at the pre-occupancy stage. In total, 107 apartments were surveyed for indoor and outdoor VOC concentrations in two metropolitan cities and one rural area in Korea. A mass balanced model was used to estimate surface area-specific emission rates of individual VOCs and formaldehyde. Seven (benzene, ethyl benzene, toluene, m,p-xylene, o-xylene, n-hexane, and n-heptane) of 40 target compounds were detectable in all indoor air samples, whereas the first five were detected in all outdoor air samples. Formaldehyde was also predominant in the indoor air samples, with a high detection frequency of 96%. The indoor concentrations were significantly higher than the outdoor concentrations for aromatics, alcohols, terpenes, and ketones. However, six halogenated VOCs exhibited similar concentrations for indoor and outdoor air samples, suggesting that they are not major components emitted from building materials. It was also suggested that a certain portion of the apartments surveyed were constructed by not following the Korean Ministry of Environment guidelines for formaldehyde emissions. Toluene exhibited the highest emission rate with a median value of 138 μg m⁻² h⁻¹. The target compounds with median emission rates greater than 20 μg m⁻² h⁻¹ were toluene, 1-propanol, formaldehyde, and 2-butanone. The wood panels/vinyl floor coverings were the largest indoor pollutant source, followed by floorings, wall coverings, adhesives, and paints. The wood panels/vinyl floor coverings contributed nearly three times more to indoor VOC concentrations than paints.     

Atmospheric emission of polychlorinated naphthalenes from iron ore sintering processes

Iron ore sintering processes constitute significant sources of dioxins, and studies have confirmed a close correlation between polychlorinated naphthalenes (PCNs) and dioxin formation. Thus, iron ore sintering processes are thought to be a potential source of PCNs, although intensive investigations on PCN emissions from sintering processes have not been carried out. Therefore, the aim of the present study was to qualify and quantify PCN emissions from nine sintering plants operating on different industrial scales. PCN concentrations ranged from 3 to 983 ng m⁻³ (0.4-23.3 pg TEQ_PCN m⁻³) and emission factors ranged from 14 to 1749 μg t⁻¹ (0.5-41.5 ng TEQ_PCN t⁻¹), with a geometric mean of 84 μg t⁻¹ (2.1 ng TEQ_PCN t⁻¹). The estimated annual emission of PCNs from sintering processes in China was 1390 mg TEQ_PCN. These figures will assist in the development of a PCN emissions inventory. Regarding emission characteristics, PCNs mainly comprised low-chlorinated homologs. The ratios of several characteristic PCN congeners were also measured and compared with those from other sources. Taken together, these results may provide useful information for identifying the sources of PCNs produced by iron ore sintering processes.     

平流层臭氧深度侵入对典型城区的影响过程分析

中纬度平流层臭氧深度侵入是造成对流层至近地面臭氧浓度突增的原因之一。筛选春夏季臭氧浓度升高时段的高分辨率大气再分析数据ERA5,以位涡值的下沉趋势分析了对流层顶折叠位置及变化过程;以AIRS数据反演了臭氧浓度、一氧化碳浓度和相对湿度的垂直廓线,并估计了其分布及相关性;以近地表污染物浓度变化、HYSPLIT模型后向轨迹分析结果证实了臭氧侵入气团的运移轨迹和局地效应;通过激光雷达监测结果观测臭氧垂直浓度分布,确定了臭氧浓度最大值所处高度,判定了受影响近地点的浓度升高时刻;以边界层高度变化、气象条件分析结果及当地与周边城市地面监测数据的逐小时变化情况等综合信息,进行了区域确认和近地面影响判定。通过以上数值综合分析,对城市地区受平流层臭氧深度侵入影响的过程和具体时间进行了详细再现,可为排除非人为排放因素导致的近地表臭氧浓度增加提供回溯分析,为臭氧污染防控决策提供依据。     

四川省水泥工业大气污染物排放水平分析

通过调研2018年四川省37条水泥生产线活动水平数据,结合企业污染治理技术,分析该省水泥工业的主要大气污染物排放水平.结果表明:2018年四川省水泥行业SO2、NOx、PM2.5和PM10的排放量分别为1.2万t、5.5万t、3.9万t和6.5万t,其不确定性主要来自污染物的产生系数和去除效率.四川省水泥生产企业各工序...     

江苏某醋厂排放VOCs的特征及健康风险评价

以江苏某醋厂为研究对象,使用便携式气相色谱/质谱仪实地采样,定性定量分析该厂挥发性有机物(VOCs)的排放特征及异味物质强度特征。采用美国环境保护署(USEPA)的健康风险评价模型,评估醋厂排放VOCs对周围居民的健康影响,结果表明,该厂排放的VOCs仅导致较强的感官影响,未产生明显的致癌效应。     

江苏省汽车零部件涂装行业VOCs排放情况初步调查

收集150家江苏省典型汽车零部件企业VOCs排放信息,对2家典型企业进行排放测试,分析江苏省该行业原辅料使用情况、产排污环节与核查要点、VOCs的排放特征,并提出最佳治理建议。研究表明,江苏省汽车零部件行业使用的涂料以溶剂型为主(占比约为79%)。废气按排放量大小依次为苯类、醇类、酯类和酮类,使用燃烧法处理后排放物种以烷烃为主,使用活性炭吸附法处理前后物种差异较小。吸附浓缩+燃烧组合处理工艺为目前最佳组合技术,处理效率 95%。