Characteristics and recent trends of sulfur dioxide at urban, rural, and background sites in North China: Effectiveness of control measures

SO₂ measurements made in recent years at sites in Beijing and its surrounding areas are performed to study the variations and trends of surface SO₂ at different types of sites in Northern China. The overall average concentrations of SO₂ are (16.8 ± 13.1) ppb, (14.8 ± 9.4) ppb, and (7.5 ± 4.0) ppb at China Meteorological Administration (CMA, Beijing urban area), Gucheng (GCH, relatively polluted rural area, 110 km to the southwest of Beijing urban area), and Shangdianzi (SDZ, clean background area, 100 km to the northeast of Beijing urban area), respectively. The SO₂ levels in winter (heating season) are 4-6 folds higher than those in summer. There are highly significant correlations among the daily means of SO₂ at different sites, indicating regional characteristics of SO₂ pollution. Diurnal patterns of surface SO₂ at all sites have a common feature with a daytime peak, which is probably caused by the downward mixing and/or the advection transport of SO₂-richer air over the North China Plain. The concentrations of SO₂ at CMA and GCH show highly significant downward trends (-4.4 ppb/yr for CMA and -2.4 ppb/yr for GCH), while a less significant trend (-0.3 ppb/yr) is identified in the data from SDZ, reflecting the character of SDZ as a regional atmospheric background site in North China. The SO₂ concentrations of all three sites show a significant decrease from period before to after the control measures for the 2008 Olympic Games, suggesting that the SO₂ pollution control has long-term effectiveness and benefits. In the post-Olympics period, the mean concentrations of SO₂ at CMA, GCH, and SDZ are (14.3 ± 11.0) ppb, (12.1 ± 7.7) ppb, and (7.5 ± 4.0) ppb, respectively, with reductions of 26%, 36%, and 13%, respectively, compared to the levels before. Detailed analysis shows that the differences of temperature, relative humidity, wind speed, and wind direction were not the dominant factors for the significant differences of SO₂ between the pre-Olympics and post-Olympics periods. By extracting the data being more representative of local or regional characteristics, a reduction of up to 40% for SO₂ in polluted areas and a reduction of 20% for regional SO₂ are obtained for the effect of control measures implemented for the Olympic Games.     

Evaluation of solubility of polycyclic aromatic hydrocarbons in ethyl lactate/water versus ethanol/water mixtures for contaminated soil remediation applications

Solubility data of recalcitrant contaminants in cosolvents is essential to determine their potential applications in enhanced soil remediation. The solubilities of phenanthrene, anthracene, fluoranthene and benzo[a]pyrene in ethyl lactate/water and ethanol/water mixtures were measured using equilibrium techniques. The cosolvency powers derived from solubility data were then applied to the model developed from the solvophobic approach to predict the capability of ethyl lactate and ethanol in enhancing the desorption of contaminants from soils. Both ethyl lactate and ethanol cosolvents were shown to be able to enhance the solubilisation of the tested four polycyclic aromatic hydrocarbons by > 4 orders of magnitude above the levels obtained with water alone. However, ethyl lactate demonstrated a greater capacity to enhance PAH solubility than ethanol. The cosolvency powers of ethyl lactate/water system obtained from the end-to-end slope (σ) and the end-to-half slope (σ_0.5) of the solubilisation curve were 1.0--1.5 and 2.0--2.9 higher than ethanol/water system respectively. In line with this, ethyl lactate/water was demonstrated to enhance the desorption of contaminants from soil by 20%--37% and 18%--61% higher compared to ethanol/water system in low organic content and high organic content soils respectively, with a 2:1 (V/W) ratio of solution:soil and with cosolvent fraction as low as 0.4. With the exception of benzo[a]pyrene, the experimental desorption results agreed fairly with the predicted values, under an applied solution:soil ratio that was enough to hold the capacity of released contaminants.     

长白山温带森林挥发性有机物的排放通量

2010年夏季,在长白山温带森林开展了挥发性有机物(VOC)排放通量以及气象参数、PAR的综合测量.VOC排放通量采用松弛涡度积累(RelaxedEddyAccumulation)技术在森林冠层上进行测量.初步发现长白山阔叶林主要排放α-蒎烯、β-蒎烯、莰烯、香桧烯、月桂烯、蒈烯、柠檬烯、罗勒烯、松油烯、繖花烃、萜品油烯、三环烯等.研究表明,长白山阔叶混交林VOC排放有明显的日变化——早晚较低和中午前后较高.2010年夏季,单萜烯总排放通量的平均值为0.242mg·m·h-2-1,其变化范围为0.005～1.668mg·m·h-2-1;各成分排放通量的平均值(和最大值)分别为α-蒎烯0.072(0.234)、莰烯0.028(0.356)、月桂烯0.027(0.433)、蒈烯0.023(0.173)、柠檬烯0.037(0.197)、罗勒烯0.016(0.168)、萜品油烯0.053(0.320)、繖花烃0.067(0.755)mg·m·h-2-1.研究还发现VOC排放通量与气温之间存在一定的联系.     

兰州市大气中苯并(a)芘与儿童尿中1-羟基芘的分析及风险评价

对兰州市不同区域空气中苯并(a)芘和儿童尿液中1-羟基芘同步采样,分别采用气相色谱-质谱联用法和高效液相色谱法进行检测.结果表明:不同区域苯并(a)芘浓度有显著差别,研究区日均浓度约为对照区日均浓度的两倍.冬季大气中的浓度明显高于夏季,其中研究区冬季均值约为夏季的26.46倍,对照区冬季均值约为夏季的29.41倍.儿童尿中1-羟基芘的浓度与空气中苯并(a)芘的浓度呈一致的变化,冬季研究区儿童尿中1-羟基芘的均值为0.86μmol·(mol肌酐)-1,对照区为0.63μmol·(mol肌酐)-1.冬季研究区儿童的终生超额危险度最高,达到2.32×10-4,接近不可接受水平.     

地质封存中CO_2盐水溶液的表观摩尔体积模型

在现有CO2盐水溶液密度模型的基础上,根据CO2地下盐水溶液密度实验数据,考虑了温度、压力和CO2质量分数三个参数的影响,建立了CO2盐水溶液的表观摩尔体积模型。模型结果表明该模型能在30~50℃、10~20 MPa温压范围内准确预测CO2在盐水溶液中的表观摩尔体积,将预测结果与实验数据进行对比发现最大相对误差为0.25%,平均相对误差为0.1%,模型预测精度明显高于现有的CO2盐水溶液表观摩尔体积模型,为CO2地下盐水层封存提供了必要的基础。     

粉煤灰基质滤料生物过滤处理生活污水研究

将粉煤灰基质滤料用于曝气生物滤池,该滤料具有较高的比表面积和孔隙率,吸附性能良好,挂膜后生物相丰富。对于中等浓度的生活污水,当水力负荷和COD有机物负荷分别控制在1.53 m3/(m2.h)、3.68 kg/(m3.d)以下时,该曝气生物滤池COD和NH3-N去除率能稳定在85%以上,出水COD和NH3-N达到排放标准要求。该曝气生物滤池对进水水质水量的变动具有较强的抗冲击负荷能力。     

吐纳麝香长期暴露下蚯蚓体内金属硫蛋白和谷胱甘肽变化

吐纳麝香(AHTN)作为人工合成麝香中多环麝香的典型代表,具有挥发性、易生物富集等特性,由于其在环境中的浓度日益升高,呈现出一定的生物效应,可能对生态系统的稳态存在着潜在的威胁,为探讨上述课题,试验通过采用自然土壤法以赤子爱胜蚓(Eiseniafetida)作为试验动物,首次研究测定蚯蚓在AHTN的长期暴露条件下,其体内金属硫蛋白和谷胱甘肽含量的变化。试验结果得出低浓度的AHTN能够抑制机体内金属硫蛋白和谷胱甘肽的生成,使得金属硫蛋白和谷胱甘肽的含量显著减少,在一定浓度范围内的AHTN对机体无明显不利影响,而高浓度的AHTN能够诱导机体内金属硫蛋白和谷胱甘肽的生成,使得金属硫蛋白和谷胱甘肽的含量显著增多(P<0.05),从而对土壤环境存在着潜在的生态风险。     

硫酸盐还原颗粒污泥对Cr的吸附机理解析

以硫酸盐还原颗粒污泥作为研究对象,进行Cr的吸附容量研究及吸附等温线拟合,测定颗粒污泥中的硫化物含量、对比实验前后颗粒污泥的表面形态和微生物组成并采用傅里叶红外变换光谱(FTIR)分析颗粒污泥的表面基团。结果表明,颗粒污泥对Cr的吸附容量为6.84 mg/g,吸附过程可用Langmuir吸附等温式描述。颗粒污泥中硫化物含量达9.868 mg/g(湿重),对应每克颗粒污泥对Cr的最大吸附量可达10.69 mg;颗粒污泥表面生长大量的微生物,以杆菌为主,颗粒污泥表面丰富的微孔结构及微生物所分泌的胞外物均可有效吸附溶液中的Cr;FTIR分析结果显示,颗粒污泥中包含大量C=O、C-N及-S等基团,这些基团均可通过与C(rⅥ)或C(rⅢ)之间的静电吸附作用吸附溶液中的Cr。研究表明化学与生物吸附作用在硫酸盐还原颗粒污泥吸附溶液中的Cr过程中起到了重要的作用。     

氨基硫脲改性山竹壳对Cd2+. Pb2+的吸附

采用氨基硫脲改性山竹壳,制备新型的改性山竹壳吸附剂,研究其对Cd2+、Pb2+的吸附性能。结果表明,吸附Cd2+、Pb2+的适宜条件为:pH 6.0,吸附时间120 min。改性后山竹吸附剂对Cd2+、Pb2+的吸附容量能有了很大程度的提高,Cd2+、Pb2+最大吸附量分别达到39.37、57.14mg/g。吸附过程可以很好地用准二级动力学方程描述,吸附等温线用Langmuir方程的拟合效果优于Freundlich方程。     

钙、镁离子在水流作用下对铜绿微囊藻生长的影响

为了解在"引江济太"过程中大量钙、镁离子的引入对铜绿微囊藻生长的影响,本实验在控制温度和光照条件下,室内模拟不同钙、镁离子浓度在两个特征流速5 cm/s和15 cm/s下微囊藻的生长。实验结果表明,微囊藻藻密度随钙、镁离子浓度的增加而增加,流速在15cm/s下微囊藻最大藻密度(9 236.4×104cell/mL)是流速为5 cm/s下最大藻密度(2 873.72×104cell/mL)的3倍,流速为15 cm/s下微囊藻最大比增长速率均较5 cm/s下的高。这可能是在水流产生的剪切力作用下藻细胞胞外多糖增加,粘附更多的钙、镁离子更利于钙、镁离子迁移到胞内,同时胞外附着的钙、镁离子尤其钙离子形成桥联,使微囊藻细胞形成群体产生微环境利于微囊藻的生长。水流对微囊藻利用钙、镁离子有重要的影响,这为有效调水抑制蓝藻生长提供科学依据。