Fabrication and photocatalytic ability of an Au/TiO<Subscript>2</Subscript>/reduced graphene oxide nanocomposite

A new type of Au/TiO₂/reduced graphene oxide (RGO) nanocomposite was fabricated by the hydrothermal synthesis of TiO₂ on graphene oxide followed by the photodeposition of Au nanoparticles. Transmission electron microscopy images showed that Au nanoparticles were loaded onto the surface of both TiO₂ and RGO. Au/TiO₂/RGO had a better photocatalytic activity than Au/ TiO₂ for the degradation of phenol. Electrochemical measurements indicated that Au/TiO₂/RGO had an improved charge transfer capability. Meanwhile, chemiluminescent analysis and electron spin resonance spectroscopy revealed that Au/TiO₂/RGO displayed high production of hydrogen peroxide and hydroxyl radicals in the photocatalytic process. This high photocatalytic performance was achieved via the addition of RGO in Au/TiO₂/RGO, where RGO served not only as a catalyst support to provide more sites for the deposition of Au nanoparticles but also as a collector to accept electrons from TiO₂ to effectively reduce photogenerated charge recombination.

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Diversity and community composition of phosphorus accumulating organisms (PAOs) in the sediments of the Sanshiliujiao Lake reservoir北大核心CSCD

The diversity and community composition of phosphorus accumulating organisms (PAOs) in the sediments of the Sanshiliujiao Lake reservoir in Pingtan island, Fujian Province, were investigated by terminal restriction fragment length polymorphism (T-RFLP) methods combined with the construction of clone libraries. The diversity of PAOs in summer samples was significantly higher than that in winter. The dominant terminal restriction fragments (T-RFs) of PAOs were in the range of 200 to 300 bp in summer, while they were in the range of 150 to 200 bp in winter. Cloning sequencing and phylogenetic analysis showed that the main phyla of PAOs in the sediment of the Sanshiliujiao Lake reservoir were Proteobacteria, Actinobacteria, and Acidobacteria. Anaeromyxobacter, Azospirillum, Microlunatus phosphovorus, and Burkholderia were the dominant genera in the summer samples. Anaeromyxobacter, Methylobacterium, Solibacter, Azospirillum, and Microlunatus phosphovorus were the dominant genera in sediment samples in winter. The results of this study demonstrated that the diversity and community composition of PAOs in the sediments of the Sanshiliujiao Lake reservoir had specific seasonal characteristics. Various forms of phosphorus also showed their influence on the diversity of PAOs, especially Fe/Al-P. Our findings lays a scientific foundation for the future disclosure of microbial mechanisms involved in the phosphorus metabolic cycle in the sediments of reservoirs. © 2018 Science Press. All rights reserved.     

纳米银和PVP包被纳米银对HepG2细胞遗传毒性的比较研究

为了探讨纳米银对HepG2细胞DNA损伤、染色体畸变等遗传毒性指标的影响,以期为纳米银体外遗传毒性评价提供参考依据,本文采用2种纳米银材料(20 nm-PVP包被纳米银、20 nm-无包被纳米银),分别以20μg·mL~(-1)、40μg·mL~(-1)、80μg·mL~(-1)、160μg·mL~(-1)的剂量对HepG2细胞染毒24 h,用Hoechst-33258染色法检测细胞凋亡,彗星实验检测DNA损伤,胞质分裂阻滞微核细胞组学试验法检测染色体畸变。结果表明,20 nm Ag NPs组在160μg·mL~(-1)时引起细胞凋亡数显著增多(P0.05);20 nm PVP-Ag NPs组在80μg·mL~(-1)和160μg·mL~(-1)剂量组中细胞凋亡数显著增多(P0.01)。2种纳米银引起HepG2细胞发生细胞凋亡,并呈剂量效应关系。彗星试验结果表明,20 nm Ag NPs和20 nm PVP-Ag NPs在40μg·mL~(-1)、80μg·mL~(-1)、160μg·mL~(-1)剂量组中,Olive尾矩、尾长和尾部DNA百分比与空白对照组相比均有显著差异(P0.05)。2种纳米银对HepG2细胞DNA损伤程度为:20 nm Ag NPs20 nm PVP-Ag NPs。胞质分裂阻滞微核细胞组学试验结果表明,2种纳米银均不会引起核质桥数发生明显改变(P0.05),20 nm Ag NPs在高染毒剂量下引起微核总数、I型微核、II型微核、核芽数明显升高(P0.05);20 nm PVP-Ag NPs在各染毒剂量下均会引起微核总数及I型微核数量升高(P0.01),II型微核数在160μg·mL~(-1)剂量下升高明显(P0.01),剂量大于20μg·mL~(-1)时核芽数升高(P0.01)。20 nm PVP-Ag NPs对细胞核的影响大于20 nm Ag NPs(P0.05)。总之,2种纳米银材料均会引起HepG2细胞DNA损伤及染色体畸变等遗传毒性效应的改变,无包被纳米银比PVP包被纳米银更容易引起DNA损伤,PVP包被纳米银比无包被纳米银更容易引起细胞染色体畸变相关效应;2种材料对HepG2细胞的损伤存在浓度-效应关系,浓度越高遗传毒性损伤越严重。     

渔塘坝微地域高Se环境中土壤Se的分布规律及其影响因素

选取迄今世界上唯一发生过人群Ｓｅ中毒的湖北恩施双河乡渔塘坝为研究区,在渔塘坝０．０１ｋｍ＾２的微地域内,土壤Ｓｅ的分布存在着显著的不均一性,控制渔坝土壤Ｓｅ分布的３个主要因素是地形,土壤粒度和成土母质的含Ｓｅ量及出露情况,其中地形是最重要的控制因素。土壤Ｓｅ的分布规律表明,在表生的中强化学风化环境Ｓｅ是一种极为活泼的元素,易于积累Ｓｅ的负地形是最易于Ｓｅ中毒发性的地貌位置。     

红外光谱法监测水中矿物油含量

本文提出了一种快速和准确监测水中矿物油环境污染指标的新方法。用多元线性回归和逐步回归法建立测油数学模型,对标准样液在３０００～２８００ｃｍ－１间的四个强吸收峰的光谱数据进行回归处理。对６３件用６种矿物油配制而成的浓度为０～４００ｍｇ／Ｌ的四氯化碳标准液进行了测定。实验结果表明,本文建立的红外光谱法测油模型对宽量程内的矿物油污染量有较好适应性。     

我国10城市冬季大气颗粒物中多环芳烃污染及呼吸暴露风险评价

大气中颗粒物和多环芳烃对环境与人体健康危害较大,已引起社会各界的广泛关注。以我国10个城市2013年12月和2014年1月大气中空气动力学直径小于10μm的颗粒物(PM10)为研究对象,采用硅胶-氧化铝层析柱净化分离、气质联用仪分析的方法测定了27种多环芳烃(PAHs)的浓度水平,分析其谱分布及空间分布,并通过呼吸暴露途径估算了癌症病发增量(ILCRs)和人群归因危险度百分比(PAF)。结果表明,27种物质的总浓度为13.72~2 002 ng·m-3;在10个城市中晋中总浓度最高,厦门最低。PAHs空间污染水平呈现北方高于南方、东部沿海城市浓度相对较低的趋势。温度与总浓度有相关性。在27种PAHs中,占主导地位的单体为荧蒽(FLA,7.56%~19.8%),芘(PYR,6.72%~13.8%),艹屈(CHR,12.8%~19.6%)和苯并(k)荧蒽(Bk F,8.59%~15.5%),4者占到多环芳烃总浓度的42.1%~64.3%。根据研究区域苯并[a]芘(Ba P)人口加权浓度估算ILCRs范围为8.94×10-6~4.77×10-4,据此计算的PAFs为0.487%~13.2%,均值为3.44%,高于全国平均水平1.6%。上述研究结果为大气颗粒物中PAHs的研究提供重要的数据基础。     

聚苯乙烯微塑料对糖尿病小鼠肾脏的影响

以糖尿病小鼠为模式生物,探究了100nm和5μφ的聚苯乙烯微塑料(PSMPs)(200μg/L)通过饮水暴露28d后对小鼠肾脏的毒性.结果表明,糖尿病小鼠对PSMPs的暴露更加敏感,100nm和5μm PSMPs暴露导致糖尿病小鼠肾脏出现明显的炎性细胞浸润和淤血等病理损伤,且 100nm PSMPs对肾脏造成的病理损伤...     

Chemical speciation and phytoavailability of Zn, Cu, Ni and Cd in soil amended with fly ash-stabilized sewage sludge

A sequential extraction method was used to determine chemical forms of Cu, Zn, Ni and Cd in fly ash-stabilized sludge. A loamy acid soil amended with fly ash-stabilized sludge was used to grow corn under greenhouse conditions. Sewage sludge amended with coal fly ash can reduce the availability of Cu, Zn, Ni and Cd in the sludge. Increasing fly ash amendment rate significantly reduced DTPA-extractable Cu, Zn, Ni and Cd concentrations. Percentages of Cu, Zn and Ni in residual fraction increased with an increase in fly ash amendment rates. Majority of Cu was associated with organic form, but Zn and Ni were associated with Fe-Mn oxide and residual forms. Addition of ash-amended sludge to soil significantly increased dry mass of corn. With coal fly ash amendment rate increasing, concentrations of Zn and Cu in shoot tissues of corn decreased significantly, but concentrations of Cd and Ni did not change significantly. Significant correlations were found between concentrations of Cu and Zn in corn shoot and oxide and total Cu fractions, and all chemical fractions of Zn in fly ash-stabilized sludge, respectively. Hence, ash amendment significantly reduced the availability of heavy metals by chemical modification of their chemical speciation into less available forms.     

Toxicity evaluation of sewage sludges in Hong Kong.

Anaerobically digested sewage sludges collected from four wastewater treatment plants located in Sha Tin, Tai Po, Yuen Long, and Shek Wu Hui in Hong Kong were subjected to chemical characterization and toxicity testing to provide preliminary assessment of their suitability for land application. All sewage sludges were slightly alkaline with pH range of 8.3-8.7. Electrical conductivity (EC; 0.69 dS m(-1)) and soluble NH4-N content (996 mg kg(-1)) of sewage sludge from Yuen Long were lower than that of other plants. Concentrations of heavy metals were determined as total, extractable, and water-soluble fraction using mixed acid digestion, DTPA (pH 7.3), and distilled water, respectively. Yuen Long sludge was most polluted with Zn and Cr higher than the pollutant concentration limits listed in Part 503 of USEPA, owing to the effluent coming from the tannery industry. High concentration of Ni was found in sludge from Sha Tin that originated mainly from the electroplating industry. DTPA-extractable Zn contents were high in sludges from Yuen Long (1247 mg kg(-1)) and Shek Wu Hui (892 mg kg(-1)), while 3.7 mg kg(-1) of DTPA-extractable Cr was found in Yuen Long sludge. Metal speciation of sludges showed that Pb was major in residual phase while Cu, Cr, and Ni in organic and residual phases, and Zn did not show any dominant chemical phase. The sludge extracts did not exert significant adverse effect on seed germination of Brassica chinensis (Chinese cabbage), but Yuen Long sludge caused a reduction in root growth. In view of its lower EC and soluble ammonia contents, the high concentration of Zn and Cr in Yuen Long sludge would likely be responsible for this adverse effect on root growth. Therefore, Yuen Long sludge would likely have a more serious impact on soil quality and plant growth as compared to other sludges. This would require further verification from greenhouse and field experiments.     

Ecosystem management based on ecosystem services and human activities: a case study in the Yanhe watershed

With activities that alter the structure and function of the habitat, humans have a direct impact on ecosystems and ecosystem services, i.e., the conditions and processes that sustain human life. In this study, 35 townships in the Yanhe watershed in the Loess Plateau of China were selected. The net primary production (NPP), carbon sequestration and oxygen production (CSOP), water conservation, and soil conservation were the ecosystem services selected and valuated. Human activity was quantified by an integrated human activity index (HAI) based on population density, farmland ratio, and the influence of road networks and residential areas. The NPP, CSOP, and water conservation showed a conspicuous spatial pattern fanning outward from the southwest, while the soil conservation showed an obscure spatial pattern distinguished primarily by the peripheral area surrounding the urbanized areas. Total ecosystem services in the Yanhe watershed demonstrated a decreasing pattern from south to north, and the HAI was in proportion to administrative and economic development. Based on the selected ecosystem services and HAI, we mapped the townships of the Yanhe watershed by cluster analysis, and provided sustainable ecosystem management suggestions, tailored to the social-ecological map.