Enhanced U(VI) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate

Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters.     

Serious BTEX pollution in rural area of the North China Plain during winter season

Atmospheric BTEX compounds(benzene, toluene, ethylbenzene and xylenes) in a rural site of the North China Plain(NCP) were preliminarily investigated in winter, and the outdoor concentrations(25.8–236.0 μg/m3) were found to be much higher than those reported in urban regions. The pollution of BTEX inside a farmer's house was even more serious, with combined concentrations of 254.5–1552.9 μg/m3. Based on the ratio of benzene to toluene(1.17 ± 0.34) measured, the serious BTEX pollution in the rural site was mainly ascribed to domestic coal combustion for heating during the winter season. With the enhancement of farmers' incomes in recent years, coal consumption by farmers in the NCP is rapidly increasing to keep their houses warm, and hence the serious air pollution in rural areas of the NCP during winter, including BTEX, should be paid great attention.     

Oxidation of Cr(III) on birnessite surfaces: The effect of goethite and kaolinite

Oxidation of Cr(III) by manganese oxides may pose a potential threat to environments due to the formation of toxic Cr(VI) species. At present, it was still unclear whether the extent of Cr(III) oxidation and fate of Cr(VI) would be changed when manganese oxides co-exist with other minerals, the case commonly occurring in soils. This study investigated the influence of goethite and kaolinite on Cr(III) oxidation by birnessite under acidic pH condition (pH 3.5) and background electrolyte of 0.01 mol/L NaCl. Goethite was found not to affect Cr(III) oxidation, which was interpreted as the result of overwhelming adsorption of cationic Cr(III) onto the negatively-charged birnessite (point of zero charge (PZC) < 3.0) rather than the positively-charged goethite (PZC = 8.8). However, more Cr(VI) would be retained by the surface with the increase in addition of goethite because of its strong ability on adsorption of Cr(VI) at low pH. Moreover, either Cr(III) oxidation or distribution of the generated Cr(VI) between the solid and solution phases was not affected by kaolinite (PZC < 3.0), indicating its low affinity for Cr species. Reactions occurring in the present mixed systems were suggested, which could be partly representative of those in the soils and further indicates that the mobility and risk of Cr(VI) would be decreased if goethite was present.     

Heterogeneous oxidation of SO2 by O3-aged black carbon and its dithiothreitol oxidative potential

Ozone (O₃) is an important atmospheric oxidant. Black carbon (BC) particles released into the atmosphere undergo an aging process via O₃ oxidation. O₃-aged BC particles may change their uptake ability toward trace reducing gases such as SO₂ in the atmosphere, leading to different environmental and health effects. In this paper, the heterogeneous reaction process between O₃-aged BC and SO₂ was explored via in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Combined with ion chromatography (IC), DRIFTS was used to qualitatively and quantitatively analyze the sulfate product. The results showed that O₃-aged BC had stronger SO₂ oxidation ability than fresh BC, and the reactive species/sites generated on the surface had an important role in the oxidation of SO₂. Relative humidity or 254 nm UV (ultraviolet) light illumination enhanced the oxidation uptake of SO₂ on O₃-aged BC. The oxidation potentials of the BC particles were detected via dithiothreitol (DTT) assay. The DTT activity over BC was decreased in the process of SO₂ reduction, with the consumption of oxidative active sites.     

两种方法测定固定污染源废气中铅的对比研究

以石英纤维滤筒采样,采用硝酸-氢氟酸消解体系,建立了火焰原子吸收光谱法和电感耦合等离子体原子发射光谱法测定固定污染源废气中铅的分析方法。分别对两种方法的波长选择、干扰因素、标准曲线、检出限、准确度和精密度等方面进行了对比研究,并对两种方法的测定结果进行t检验。结果表明,两种方法无显著性差异,均可用于固定污染源废气中铅的含量测定。     

衡水市道路交通环境颗粒物污染特性及控制对策研究

针对衡水市机动车污染问题,本文选择衡水市代表性路段,对其进行了实验,如采样点的确定、采样时间和频率、监测方法及标准和使用的实验仪器,得到了结果与分析,如交通环境中PM10和TSP的变化特征、PM10/TSP比值和交通环境中PM10和TSP的影响因素分析,并提出衡水市道路交通环境空气污染控制措施,主要是完善城市交通和城市规划、城市绿化、发展清洁能源、完善管理体制和加强交通管理宣传教育,给出了切实可行的改善和控制措施.     

富里酸在土壤环境中的吸附研究

富里酸在土壤中的吸附影响着土壤肥力和土壤环境,本文比较了不同pH、离子强度下,富里酸对土壤环境吸附性能的影响,探究了高岭土对富里酸的吸附条件.结果表明吸附在高岭土上的富里酸可以改变高岭土的结构,与高岭土空白样相比,复合体的结构更加分散.高岭土的不同组分对富里酸的吸附容量不同,对富里酸不同官能团的亲和性也存在明显差异.富里酸在高岭土上的吸附及有机污染物在土壤环境中的吸附作用,与烷基、芳香基团呈正相关.     

贵州喀斯特地区土壤细菌群落结构特征及变化

为探明贵州喀斯特不同植被演替群落下的土壤细菌群落结构及变化特征,本文利用高通量测序技术对5个主要植被演替群落(稀灌草丛、藤刺灌丛、灌木林、乔灌过渡林、乔木林)的根际(竹叶椒)、非根际土壤细菌群落结构及环境因子进行了分析研究。结果表明:贵州喀斯特高原土壤细菌类群主要为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、疣微菌门(Verrucomicrobia)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)和浮霉菌门(Planctomycetes),其相对丰富度分别为43.35%、12.97%、7.53%、7.12%、6.19%、5.35%、5.05%,未分类类群占7.36%。样品中检测到了较低丰度的广古菌门和泉古菌门。随植被群落演替,根际土壤中变形菌门、厚壁菌门和浮霉菌门丰度逐渐增加;非根际土壤中酸杆菌门和疣微菌门丰度随植被演替逐渐减小。贵州喀斯特高原土壤细菌的影响因子大小为土壤有机碳、土壤总氮、含水量、电导率等,其中土壤有机碳和土壤总氮有显著性影响。     

气相分子吸收光谱法测定氨氮校准曲线斜率、截距参考值研究

主要阐述了气相分子吸收光谱法测定氨氮的校准曲线斜率、截距参考值的分析.文章收集了临安市环境监测站实验室自2012年以来气相分子吸收光谱法氨氮校准曲线制作的一系列原始数据,并通过数理统计方法对校准曲线、残余标准偏差、斜率扩展不确定度、截距扩展不确定度开展了详细讨论,得出气相分子吸收光谱法氨氮校准曲线截距a值、斜率b值实验室参考值.此结果对实验室分析人员判定氨氮项目校准曲线制作是否合格具有一定的参考价值.     

基于RIAM模型的生态旅游开发环境影响评价研究

RIAM (Rapid Impact Assessment Matrix)是进行环境影响快速识别的半定量评价方法,能综合考虑项目对自然环境-生物生态-社会文化-经济发展的影响,评价过程较传统评价方法更为透明公开.以武夷山生态旅游开发项目为例,应用RIAM模型进行生态环评,可以明确地表达项目的综合环境影响,使各种替代方案环境影响对比清晰明了,且还能快速判断出生态旅游开发的主要负环境影响排序.RIAM环评方法使环评过程透明,环评结果表达直观,能更好服务于环境决策和管理.