不同边沿高度油池火燃烧行为的实验和数值模拟研究

采用实验和FDS数值模拟相结合的方法,探讨了边沿高度对油池火燃烧特性的影响。在实验部分,研究了燃烧速率和表观火焰高度随边沿高度的变化趋势,并分别分析了各个阶段的热反馈机制。在实验获得不同尺度、边沿高度正庚烷油池火燃烧速率的前提下,建立相应尺度的不同边沿高度油池火的Fire Dynamics Simulator(FDS)计算模型以针对火焰高度进行了数值模拟研究,分析了实际火焰高度、火焰下探高度随边沿高度的变化趋势,并提出了相关的无量纲拟合式。     

Characteristic and mechanism of sorption and desorption of benzene on humic acid

Environmental Science and Pollution Research - The sorption/desorption behaviors of benzene, toluene, ethylbenzene, and xylene (BTEX) on soil organic matter (SOM) have a significant influence on...     

The associations of air pollution exposure during pregnancy with fetal growth and anthropometric measurements at birth: a systematic review and meta-analysis

Environmental Science and Pollution Research - Fetal growth has been demonstrated to be an important predictor of perinatal and postnatal health. Although the effects of maternal exposure to air...     

Photodegradation of TCDD in soil containing organic solvents

Studies were conducted to understand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) behaviour in the near surface zone in relation to the operating conditions: UV-intensity, temperature and exposure modes. Comparisons have been made between Oriel lamp exposure tests and sunlight exposure tests. Under Oriel lamp exposure, the convective transport of TCDD, which depends on operating temperature, was the limiting factor in the cleanup process. The product differences between Oriel exposure tests and sunlight exposure tests probably result from the difference of UV-intensities.     

Eutrophication conditions and ecological status in typical bays of Lake Taihu in China

Sampling was conducted at three site groups, group E (in East Taihu Bay), G (in Gonghu Bay) and M (in Meiliang Bay) in Lake Taihu. TN and TP concentrations among site groups was in the increasing order of E < G < M. TP level at G sites is at the critical threshold for loss of submersed macrophytes. Mean values of DO and Transparence showed different trend, i.e., E > G > M. The mean phytoplankton fresh-weight biomass at M sites was 5.81 mg/l, higher than that at E sites (4.96 mg/l) and G sites (5.18 mg/l). Mean zooplankton fresh-weight biomass was in the decreasing order of M (6.4 mg/l) > G (4.9 mg/l) > E (2.7 mg/l). However, Rotifera density was in the sequence of E > G > M. Both zooplankton biomass and phytoplankton biomass increased with the rise of TN and TP concentrations. Relationships between zooplankton biomass and phytoplankton biomass showed that zooplankton played a limited role in the control of algae in eutrophic lakes. Nutrient availability is much more important than zooplankton grazing pressure in controlling phytoplankton growth in lakes. For most sites in Lake Taihu, reduction of nutrient loading, as well as macrophyte conservation, zappears to be especially important in maintaining high water quality and regulating lake biological structure, but for M sites, it’s urgent to control nutrient inputs rather than to restore macrophyte community.     

DOC+CDPF对国III重型柴油货车实际道路排放的影响

利用便携式车载排放测试系统（PEMS）对2辆加装氧化催化转化器（DOC）和催化型柴油颗粒捕集器（CDPF）与否的国III重型柴油货车进行实际道路排放测试.结果表明,2辆改造重型柴油车的CO、THC、固态颗粒物粒数（SPN）和黑碳（BC）实际道路排放因子分别为（1.31±0.37）g/（kW×h）、（0.20±0.03） g/（kW×h）、（7.13×10¹⁰±5.27×10¹⁰）个/（kW×h）和（0.69±0.06）mg/（kW×h）,相对于原始排放（拆除DOC+CDPF）分别降低52.48%、55.69%、99.91%和99.22%.从低速、中速到高速,CO和THC减排比例呈现上升趋势,然而运行工况对SPN和BC减排比例则无显著影响.加装DOC+CDPF会导致NO₂在NO_x中的占比升高,且从低速、中速到高速涨幅依次增大,但对NO_x无明显减排效益,其排放因子为9.53~9.83g/（kW×h）,远高于实验室排放限值.     

Phosphate recovery with granular acid-activated neutralized red mud: Fixed-bed column performance and breakthrough curve modelling

Granular acid-activated neutralized red mud (AaN-RM) has been successfully prepared with good chemical stability and physical strength. However, its potential for industrial application remains unknown. Therefore, the performance of granular AaN-RM for phosphate recovery in a fixed-bed column was investigated. The results demonstrated that the phosphate adsorption performance of granular AaN-RM in a fixed-bed column was affected by various operational parameters, such as the bed depth, flow rate, initial solution pH and initial phosphate concentration. With the optimal empty-bed contact time (EBCT) of 24.27 min, the number of processed bed volumes and the phosphate adsorption capacity reached 496.95 and 84.80 mg/g, respectively. Then, the saturated fixed-bed column could be effectively regenerated with a 0.5 mol/L HCl solution. The desorption efficiency remained as high as 83.45% with a low weight loss of 3.57% in the fifth regeneration cycle. In addition, breakthrough curve modelling showed that a 5-9-1 feed-forward artificial neural network (ANN) could be effectively applied for the optimization of the fixed-bed adsorption system; the coefficient of determination (R²) and the root mean square error (RMSE) evaluated on the validation-testing data were 0.9987 and 0.0183, respectively. Therefore, granular AaN-RM fixed-bed adsorption exhibits promising potential for phosphate removal and recovery from polluted water.     

Mechanism and catalytic performance for direct dimethyl ether synthesis by CO2 hydrogenation over CuZnZr/ferrierite hybrid catalyst

Direct synthesis of dimethyl ether(DME) by CO_2 hydrogenation has been investigated over three hybrid catalysts prepared by different methods:co-precipitation,sol-gel,and solid grinding to produce mixed Cu,ZnO,ZrO_2 catalysts that were physically mixed with a commercial ferrierite(FER) zeolite.The catalysts were characterized by N_2 physisorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),temperature programmed desorption of CO_2(CO_2-TPD),temperature programmed desorption of NH_3(NH_3-TPD),and temperature programmed H2 reduction(H_2-TPR).The results demonstrate that smaller CuO and Cu crystallite sizes resulting in better dispersion of the active phases,higher surface area,and lower reduction temperature are all favorable for catalytic activity.The reaction mechanism has been studied using in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS).Methanol appears to be formed via the bidentate-formate(b-HCOO) species undergoing stepwise hydrogenation,while DME formation occurs from methanol dehydration and reaction of two surface methoxy groups.     

京津冀城市群二氧化碳排放达峰研究

基于IPCC排放因子方法建立了2015—2019年京津冀城市群地级城市CO₂排放清单,基于经济增长与CO₂排放关系的脱钩系数法,得到京津冀城市群13个地级以上城市的脱钩情况,结合历史CO₂排放和脱钩情况提出的京津冀城市群达峰判别方法,对京津冀城市群地级以上城市CO₂排放达峰情况进行了判断。结果表明:近5年来,保定、张家口、秦皇岛、邢台、沧州、廊坊、衡水7市碳排放量暂未达到峰值状态;北京、天津、石家庄、承德、邯郸、唐山6个城市已经处于CO₂排放达峰状态。建议已经具备达峰条件的城市抓紧开展达峰行动方案,制定CO₂排放达峰目标。