电除尘器电场特性实验研究与数值分析

数值分析是研究电除尘器电场特性的重要手段,有助于电除尘器电极配置的设计选型以及提高其供电控制水平。本文在实验的基础上,建立和求解电晕电场的数学模型,采用有限元有限差分法对RS线的电晕电场进行计算,计算结果与实验测试结果基本吻合。     

汾河流域水系和表层沉积物中多环芳烃的空间变化规律及其生态风险研究

本研究在汾河流域上、中、下游及其部分支流布设29个采样点,对其水体和表层沉积物多环芳烃(PAHs)的空间分布规律及生态风险进行了分析和讨论。结果表明,汾河流域水相中丰水期PAHs总量浓度范围是0.530~16.002μg·L~(-1),平均浓度为(2.738±3.078)μg·L~(-1),枯水期PAHs总量浓度范围是0.588~12.916μg·L~(-1),均值为(2.762±3.132)μg·L~(-1)。就空间分布而言,汾河流域整体呈现上游污染较轻,中下游污染严重的特点。PAHs的组成规律显示,丰水期和枯水期PAHs含量均以低环(2~3环)为主,不同采样期低环PAHs所占比例分别为96.5%和90.4%。与其他15个研究地区水体PAHs含量比较,汾河流域水体中PAHs污染程度的国内外对比处于中等到较高程度的污染。丰水期和枯水期水体中PAHs来源于石油源和植物、木材、煤的燃烧,主要受到流域煤化工、燃煤电厂排放污染物的影响。地表水健康风险评价结果显示,汾河流域丰水期和枯水期分别有13.8%和20.7%的点位存在一定的健康风险。汾河流域沉积相中16种PAHs平均浓度为(3.774±1.987)μg·g-1,其污染主要集中在流域中下游地区。PAHs的组成规律显示,PAHs含量集中在低环(2~3环),约占总量的75%左右。与本研究提到的河流、湖泊及港口沉积物中PAHs含量比较,汾河流域沉积物中PAHs污染程度仍处于中等偏高的污染水平。丰水期沉积相中PAHs以燃烧源和石油源为主,部分来自典型石油类产品的输入。表层沉积物生态风险评价结果显示,对于提出的12种PAHs的生态风险的效应区间低值(ERL值)或效应区间中值(ERM值)以及苯并(b)荧蒽(Bb F)和苯并(k)荧蒽(Bk F)这2类没有最低安全值的PAHs化合物来说,汾河上、中、下游流域均有采样点的PAHs可能存在着对生物的潜在生态风险。通过本研究可全面地了解该流域多环芳烃的空间分布规律及其可能的来源,并且为汾河流域多环芳烃污染的控制和生态风险评价提供科学依据。     

铜、锌氰配合物在离子交换纤维上的扩散、吸附机理

运用Boyd液膜扩散公式和范山鹰等提出的扩散模型,考察了碱性溶液中铜、锌氰配合物在离子交换纤维上的扩散行为;通过分析吸附前后纤维上官能团的位置变化以及解吸前后纤维上元素含量的变化,研究铜、锌氰配合物在纤维上的吸附机理。实验结果表明,离子交换纤维对铜、锌配合物的吸附在反应初期,以液膜扩散为主控制步骤,反应后期,以空隙扩散为主控制步骤。并运用离子交换纤维在水溶液中具有类似胶体型物质的双电层结构解释了不同控制阶段吸附速率不同的原因,虽然各阶段吸附速率有所不同,但纤维对铜、锌氰配合物的吸附均为离子交换机制。     

吸附联合低温等离子体法去除甲苯废气

对介质阻挡放电条件下产生的低温等离子体联合吸附去除低浓度甲苯废气进行了实验研究。考察了反应器内分别填充分子筛、陶瓷环和混合填料时,甲苯的吸附效果;比较了各种填充条件下,低温等离子体对甲苯的去除效果和副产物臭氧的产生量;并对填充混合填料时不同外加电压、不同操作条件下,吸附联合低温等离子体去除甲苯的过程进行系统的研究。结果表明,外加电压相同,混合填料对甲苯的去除率最高,大于97%,依次是分子筛、陶瓷环、无填充;同时混合填料的臭氧浓度小于其他填料;当电压为18 kV时,混合填料可获得较高的甲苯去除率,同时产生的臭氧副产物最少。     

施用城市污泥堆肥对土壤微生物群落结构变化的影响

在温室条件下进行了15周的盆栽实验,考察了施用城市污泥堆肥后,土壤中养分含量的变化规律,重点研究了施用城市污泥堆肥对土壤微生物群落结构变化的影响。实验发现,污泥堆肥能改善土壤养分,有机质和氮、磷含量得到显著提高。经PCR—DGGE分析,施肥1周后土壤中细菌和真菌的群落结构均发生了较大的变化。随着施肥时间的延长,细菌在富含有机质及氮、磷等养分的土壤环境下大量生长,多样性提高,其优势菌群属于γ变形菌、α变形菌和芽单胞菌;随着有机质的不断消耗,细菌的生长活性受到抑制,最终由于养分的缺乏,细菌种群多样性呈现小幅度的降低,优势菌群变为绿弯菌门、γ变形菌亚纲和厚壁菌门。对于真菌,其多样性指数在堆肥前3周逐渐提升,在第3～12周的监测中呈现相对稳定的变化趋势,优势菌群主要为座囊菌纲和散囊菌纲。     

Simulated Impacts of Climate Change on Current Farming Locations of Striped Catfish (Pangasianodon hypophthalmus; Sauvage) in the Mekong Delta,Vietnam

In Vietnam, culturing striped catfish makes an important contribution to the Mekong Delta’s economy. Water level rise during rainy season and salt intrusion during dry season affect the water exchange and quality for this culture. Sea level rise as a consequence of climate change will worsen these influences. In this study, water level rise and salt water intrusion for three sea level rise (SLR) scenarios (i.e., +30, +50, and +75 cm) were simulated. The results showed that at SLR +50, the 3-m-flood level would spread downstream and threaten farms located in AnGiang, DongThap and CanTho provinces. Rising salinity levels for SLR +75 would reduce the window appropriate for the culture in SocTrang and BenTre provinces, and in TienGiang’s coastal districts. Next to increasing dikes to reduce the impacts, the most tenable and least disruptive option to the farming community would be to shift to a salinity tolerant strain of catfish.     

小龙潭电厂脱硫工艺的探讨

介绍了国外几种成熟的脱硫工艺，通过分析与比较并结合小龙潭电厂的实际情况，最终选择烟气循环流化床半干法作为该电厂褐煤锅炉的脱硫工艺。     

Study of the Climate Change Impacts on Water Quality in the Upstream Portion of the Cau River Basin,Vietnam

This paper presents simulations of climate change impacts on water quality in the upstream portion of the Cau River Basin in the North of Vietnam. The integrated modeling system GIBSI was used to simulate hydrological processes, pollutant and sediment wash-off in the river basin, and pollutant transport and transformation in the river network. Three projections for climate change based on emission scenarios B1, B2, and A2 of IPCC Special Report on Emission Scenarios (SRES) were considered. By assuming that the input pollution sources and watershed configuration were constant, based on 2008 data, water quality in the river network was simulated up to the terminal year 2050. For each climate change scenario, patterns of precipitation in wet and dry year were considered. The change in annual and monthly trends for dissolved oxygen (DO), biochemical oxygen demand (BOD), and ammonium ions (NH4+) load and concentration for different portions of the watershed have been analyzed. The results of these simulations show that climate change has more impact on changing the seasonal water quality parameters than on altering the average annual load of the pollutants. The percent change and change pattern in water quality parameters are different for wet and dry year, and the changes in wet year are smaller than those in dry year.     

Human exposure to methylmercury from crayfish (Procambarus clarkii) in China

Methylmercury (MeHg) accumulation in aquatic food raises global concerns about human exposure to MeHg. Crayfish is the world’s third largest farmed crustacean species and a favorite aquatic food in many countries. However, human health hazard due to MeHg exposure via crayfish consumption is unclear, partly because appropriate survey data are lacking. We report on mercury concentrations and speciation in edible tail muscle of crayfish collected from restaurants in 23 Chinese cities. On average, MeHg constituted 99.1 % of mercury in tail muscle, and MeHg concentrations were comparable with those reported for fish in China. Variation in MeHg concentrations was not attributable to broad geographic region (i.e., provinces) or tail length. For different populations, potential health risk (characterized by hazard quotient or HQ) of MeHg exposure through crayfish consumption depended largely on crayfish consumption rates. In particular, a health hazard (HQ > 1) was found for high-rate consumers (i.e., 95 %ile or higher) in some cities in the middle and lower reaches of the Yangtze River (MLYR), during the peak consumption season. Our results suggest that more attention should be paid to dietary MeHg intake via crayfish consumption in China, particularly for communities with high consumption in MLYR.

     

抗菌消费品中纳米银含量调查及银的健康风险评价

纳米银(Ag NP)因具有良好的抗菌特性被广泛应用于日常消费品中,人体主要通过皮肤接触或口服等方式暴露于Ag NP。为了评价这些抗菌消费品中银对成人的非致癌暴露风险,对市面10种日常抗菌消费品中Ag NP和总银含量进行了调查,并采用美国环保局推荐的皮肤和口部暴露途径的健康风险评估模型来评价含银抗菌消费品引起的皮肤及口部非致癌暴露风险。调查结果表明:4种液态抗菌消费品中检测出Ag NP,含量为0.79~57.89 mg·L~(-1),占其总银含量的8.8%~99.1%。其他厂家标注含有Ag NP的抗菌消费品中则未检测出Ag NP。风险评价结果显示,大多数抗菌消费品的银风险熵为3.6×10-4~6.8×10-1,其中经皮肤暴露的银非致癌风险熵为1.0×10-3~6.8×10-1,经口暴露的银风险熵为3.6×10-4~6.0×10-3,对人体健康不会产生显著风险;然而,其中1种抗菌消费品中银的风险熵上限为0.86,接近于1,存在潜在的非致癌风险。