Surface characterization of metal oxides-supported activated carbon fiber catalysts for simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide

The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS) and carbon disulfide (CS₂) at relatively low temperatures of 60°C was tested. The effects of preparation conditions on the catalyst properties were investigated, including the kinds and amount of metal oxides and calcination temperatures. The activity tests indicated that catalysts with 5 wt.% Ni after calcining at 400°C (Ni(5)/ACF(400)) had the best performance for the simultaneous catalytic hydrolysis of COS and CS₂. The surface and structure properties of prepared ACF were characterized by scanning electron microscope-energy disperse spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), carbon dioxide-temperature programmed desorption (CO₂-TPD) and diffuse reflectance Fourier transform infrared reflection (DRFTIR). And the metal cation defects were researched by electron paramagnetic resonance (EPR) method. The characterization results showed that the supporting of Ni on the ACF made the ACF catalyst show alkaline and increased the specific surface area and the number of micropores, then improved catalytic hydrolysis activity. The DRFTIR results revealed that -OH species could facilitate the hydrolysis of COS and CS₂; -COO and -C–O species could facilitate the oxidation of catalytic hydrolysate H₂S. And the EPR results showed that high calcination temperature conditions provide more active reaction center for the COS and CS₂ adsorption.     

Linkage between water soluble organic matter and bacterial community in sediment from a shallow, eutrophic lake, Lake Chaohu, China

Lacustrine sediment played important roles in migration and transformation of its water soluble organic matter (WSOM), and the source and composition of WSOM would affect water trophic status and the fate of pollutants. However, we know little about the pathway of WSOM transformation and its driving bacterial communities in lacustrine sediment. In the present study, we investigated the spatial distribution patterns of sediment WSOM and its fluorescent fractions across Lake Chaohu using fluorescence spectroscopy, and explored WSOM compositional structure through our proposed calculated ratios. In addition, we also analyzed sediment bacterial community using Illumina sequencing technology, and probed the possible pathway of sediment WSOM transformation under the mediate of indigenous bacteria. Our results showed that the inflowing rivers affected the spatial distribution patterns of WSOM and its five fractions (including tyrosine-, tryptophan-, fulvic acid-, humic acid-like substances and soluble microbial productions), and sediment WSOM originated from fresh algae detritus or bacterial sources. In parallel, we also found that Proteobacteria (mainly γ-Proteobacteria and δ-Proteobacteria), Firmicutes (mainly Bacilli), Chloroflexi, Acidobacteria, Planctomycetes and Actinobacteria dominate sediment bacterial community. Furthermore, these dominant bacteria triggered sediment WSOM transformation, specifically, the humic acid-like substances could be converted into fulvic acid-like substances, and further degraded into aromatic protein-like and SMP substances. In addition, our proposed ratios (P-L:H-L, Ar-P:SMP and H-L ratio), as supplementary tool, were effective to reveal WSOM composition structure. These results figured out possible pathway of WSOM transformation, and revealed its microbial mechanism in lacustrine sediment.     

农村环境污染来源分析及监测研究——以杨庄村为例

农村环境污染源主体分散、隐蔽、排放随即、不确定,产生的污染物面广、量大、分散、成分杂、治理难度大。为科学合理地监测农村环境,首先对农村环境中如固体废物、环境空气、土壤、地表水、地下水及声环境污染的来源进行了分析;在此基础上根据污染源的类型、属性,针对性地提出了各种不同环境要素监测点位布设时需要考虑的问题;以西安市杨庄村为例开展土壤、环境空气、地下水饮用水监测,并对监测结果等进行分析评价。     

不同来源废水中TOC与COD相关性研究

对纺织染整、化工、制药、食品加工各行业生产废水及城镇污水厂处理设施出水中的TOC(自动仪器监测)与COD(实验室手工分析)测定值进行回归分析,并检验一元线性回归方程的显著性和有效性。结果表明,各行业生产废水中TOC与COD值均存在非常显著的相关性,且废水组成成分越单一稳定,其相关性越好,同行业废水中TOC与COD回归方程的斜率b较为接近。利用TOC自动在线监测值换算所得的COD值,准确性和稳定性高,能满足水质实时连续监测的需要。     

TiO2表面沉积Ag粒子及其可见光下降解含盐废水中的苯酚

为了制备可见光激发下能高效降解含盐废水中有机物的光催化剂,首次以商用TiO_2光催化剂(P25)为载体,利用吸附相反应技术一步获得了Ag沉积的可见光响应复合光催化剂.同时,通过XPS、TEM、HRTEM及紫外可见漫反射光谱图,结合多种高含盐水体系中苯酚的光催化降解过程,研究了不同Ag沉积对催化剂可见光活性的影响.结果发现,吸附平衡后P25表面富含水的吸附层可作为反应和粒子的生成场所,生成量子尺寸的Ag粒子.另外,在吸附层中生成的Ag粒子均匀分布于P25表面并与之紧密结合,并在TiO_2晶格结构中引入晶格交错结构.Ag与TiO_2的表面等离子体共振效应和晶格交错结构共同提升了催化剂的可见光响应和电荷的分离效率,增强了催化剂对苯酚的可见光催化性能.在含盐废水体系中,盐离子数量越多,催化剂在可见光下降解苯酚过程受到的干扰越大.     

基于高斯模型的新场气田输气管道泄漏模拟研究

基于高斯烟团模型建立了适合新场气田的输气管道泄漏模型,考虑了管道压力、泄漏衰减、环境因素的影响,模拟分析了管道压力、泄漏时间与大气稳定度对泄漏天然气燃爆区域的影响,并计算获得了新场气田某干线天然气泄漏下风向燃爆极限距离图版,对指导管道安全政策、方案制定具有重要意义。     

Uranium speciation in coal bottom ash investigated via X-ray absorption fine structure and X-ray photoelectron spectra

Similar to chromium contamination, the environmental contamination caused by uranium in radioactive coal bottom ash (CBA) is primarily dependent on the chemical speciation of uranium. However, the relationship between uranium speciation and environmental contamination has not been adequately studied. To determine the relationship between uranium speciation and environmental contamination, X-ray absorption fine structure (XAFS) and X-ray photoelectron spectra (XPS) analyses were performed to determine the uranium speciation in CBA exposed to different chemical environments and simulated natural environments. The leachability of the different forms of uranium in the CBA was studied via a simulated acid rain leaching experiment, and the results showed that 57.0% of the total uranium was leached out as U(VI). The results of a linear combination fit (LCF) of the X-ray absorption near edge structure (XANES) spectrum revealed that in the raw CBA, the uranium mainly occurred as U3O8 (71.8%). However, in the iron-rich particles, the uranium mainly occurred as UO2 (91.9%) after magnetic separation. Magnetite is a ubiquitous ferrous-bearing oxide, and it was effective for the sorption of U(IV). The result of FeSO4 leaching experiment indicated that 96.57% of total uranium was reduced from U(VI) to U(IV) when infiltrated with the FeSO4 solution for 6 months. This result clearly demonstrated the changes in chemical valence of uranium in the coal ash and provided a conceptual principle for preventing uranium migration from ash to the surrounding soil and plants.     

Intranasal administration of tetrabromobisphenol A bis(2-hydroxyethyl ether) induces neurobehavioral changes in neonatal Sprague Dawley rats

Tetrabromobisphenol A (TBBPA) and its derivatives are now being highly concerned due to their emerging environmental occurrence and deleterious effects on non-target organisms. Considering the potential neurotoxicity of TBBPA derivatives which has been demonstrated in vitro, what could happen in vivo is worthy of being studied. Tetrabromobisphenol A bis(2-hydroxyethyl ether) (TBBPA-BHEE), a representative TBBPA derivative, was selected for a 21-day exposure experiment on neonatal Sprague Dawley (SD) rats through intranasal administration. The neurobehavioral, histopathological changes, and differentially expressed genes based on RNA microarray were investigated to evaluate the neurological effects of this chemical. The results indicated that TBBPA-BHEE exposure significantly compromised the motor co-ordination performance and the locomotor activities (p < 0.05). The neurobehavioral phenotype could be attributed to the obvious histopathological changes in both cerebrum and cerebellum, such as neural cell swelling, microglial activation and proliferation. A total of 911 genes were up-regulated, whereas 433 genes were down-regulated. Gene set enrichment analysis showed multiple signaling pathways, including ubiquitin-mediated proteolysis and wingless-int (Wnt) signaling pathway etc. were involved due to TBBPA-BHEE exposure. The gene ontology enrichment analysis showed the basic cellular function and the neurological processes like synaptic transmission were influenced. The toxicological effects of TBBPA-BHEE observed in this study suggested the potential neuronal threaten from unintended exposure, which would be of great value in the biosafety evaluation of TBBPA derivatives.     

公众参与在战略环境影响评价中的发展研究

公众参与是战略环境影响评价的一个显著的特点,公众参与使得决策制定过程具有更公开、更透明化的特点,同时也使得利益相关者和受影响的人群更容易接受规划和项目的实施.概述了公众参与在战略环境评价的理论发展过程,列举了近年来战略环境影响评价公众参与在国外的实践经验,讨论了中国公众参与在战略环境影响评价的研究成果,最后提出了完善中国战略环境影响评价公众参与制度的合理建议.     

Comparison of surface water chemistry and weathering effects of two lake basins in the Changtang Nature Reserve, China

The geochemistry of natural waters in the Changtang Nature Reserve,northern Tibet,can help us understand the geology of catchments,and provide additional insight in surface processes that influence water chemistry such as rock weathering on the Qinghai–Tibet Plateau.However,severe natural conditions are responsible for a lack of scientific data for this area.This study represents the first investigation of the chemical composition of surface waters and weathering effects in two lake basins in the reserve(Lake Dogaicoring Qiangco and Lake Longwei Co).The results indicate that total dissolved solids(TDS)in the two lakes are significantly higher than in other gauged lakes on the Qinghai–Tibet Plateau,reaching 20–40 g/L,and that TDS of the tectonic lake(Lake Dogaicoring Qiangco)is significantly higher than that of the barrier lake(Lake Longwei Co).Na+and Cl-are the dominant ions in the lake waters as well as in the glacier-fed lake inflows,with chemical compositions mainly affected by halite weathering.In contrast,ion contents of inflowing rivers fed by nearby runoff are lower and concentrations of dominant ions are not significant.Evaporite,silicate,and carbonate weathering has relatively equal effects on these rivers.Due to their limited scope,small streams near the lakes are less affected by carbonate than by silicate weathering.