制备条件对稀土掺杂TiO_2物理性质和光催化降解吡唑草胺性能的影响（英文）

多相光催化是一种非常有效的降解各种水污染物的方法.本文以稀土(镝和镨)掺杂的TiO2为光催化剂,考察了制备条件对其物理性质和光催化性能的影响.采用溶胶-凝胶法和不同条件(反应温度450,550,650 oC;反应时间4,8,12 h)的固态反应法制备了TiO2样品.运用X射线衍射分析了该样品的晶相,发现只存在锐钛矿相,并得到Raman光谱的证实.同时采用扫描电镜观察了样品的结构和粒径;以BET法计算了其比表面积;运用紫外-可见光漫反射光谱测得了样品的带隙能量.通过测量紫外光照射下常用除草剂吡唑草胺的降解速率评价了样品的光催化活性,反应过程中吡唑草胺的浓度用高效液相色谱分析.结果表明,稀土掺杂使得TiO2吸收边红移,并提高了其光催化活性;制备时最优的固态反应条件为550 oC反应8 h.

Estimating interaction between surface water and groundwater in a permafrost region of the northern Tibetan Plateau using heat tracing method

Understanding the interaction between groundwater and surface water in permafrost regions is essential to study flood frequencies and river water quality, especially in the high latitude/altitude basins. The application of heat tracing method,based on oscillating streambed temperature signals, is a promising geophysical method for identifying and quantifying the interaction between groundwater and surface water. Analytical analysis based on a one-dimensional convective-conductive heat transport equation combined with the fiber-optic distributed temperature sensing method was applied on a streambed of a mountainous permafrost region in the Yeniugou Basin, located in the upper Heihe River on the northern Tibetan Plateau. The results indicated that low connectivity existed between the stream and groundwater in permafrost regions.The interaction between surface water and groundwater increased with the thawing of the active layer. This study demonstrates that the heat tracing method can be applied to study surface water-groundwater interaction over temporal and spatial scales in permafrost regions.

Synthesis of novel adsorbent by intercalation of biopolymer in LDH for the removal of arsenic from synthetic and natural water

This study focuses on the synthesis of nanocomposites named CCA and CZA that were prepared by the incorporation of cellulose(CL)in the Ca/Al and Zn/Al layered double hydroxide(LDH),respectively.These materials were then used for the uptake of As(Ⅲ)and As(V)from aqueous medium.Characterization of both nanocomposites(CCA and CZA)was done using FTIR and Raman analysis to identify the functional groups,N2 adsorption-desorption isotherms to determine the specific surface area and pore geometry and XPS analysis to obtain the surface atomic composition.Some other characters were investigated using simultaneous TGA and DTA and elemental chemical analysis(CHNS/O).The crystallinity of the prepared nanocomposites was displayed by XRD patterns.Furthermore,the sheet-like structure of the LDHs and the irregularity of surface morphology with porous structure were observed by TEM and SEM microphotographs.Optimization of maximum adsorption capacity was adjusted using different parameters including pH,contact time and adsorbent dosage.The pseudo-second-order model was in good fitting with kinetics results.The adsorption isotherm results showed that CZA exhibits better adsorption capacity for As(Ⅲ)than CCA and the Langmuir isotherm model described the data well for both nanocomposites.Thermodynamic studies illustrated the endothermic nature of CCA and exothermic nature on CZA,as well as the fact that the adsorption process is spontaneous.A real water sample collected from well located in Gabes(Tunisia),has also been treated.The obtained experimental results were confirmed that these sorbents are efficient for the treatment of hazardous toxic species such as.

Trace elements and rare earth elements in wet deposition of Lijiang,Mt.Yulong region,southeastern edge of the Tibetan Plateau

In order to investigate the compositions and wet deposition fluxes of trace elements and rare earth elements（REEs） in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace elements and REEs were higher during the non-monsoon season than during the monsoon season,indicating that the lower concentrations of trace elements and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace elements in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities（e.g., the increasing traffic emissions from the rapid development of tourism） were most likely important contributors to trace elements, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future.

Synthesis and application of biocompatible nontoxic nanoparticles for reclamation of Ce^3＋ from synthetic wastewater： Toxicity assessment, kinetic, isotherm and thermodynamic study

The aim of present study is to synthesize forsterite nanoparticles（FRST） for the reclamation of cerium ions（Ce3＋） from synthetic wastewater.The aim to synthesize FRST nanoparticles is due to its biocompatible and nontoxic nature.The formation of nanoparticles with average diameter of 58 nm was confirmed by TEM analysis.SEM images of bare FRST nanoparticles show a heterogeneous surface with porous nature.BET surface area of FRST nanoparticles is calculated to be 33.69 m2/g.The significant uptake of Ce3＋ ions can be obtained for all the selected concentrations（25-150 mg/L） within 2 h of adsorbent—adsorbate interaction.The pH study shows that by increasing pH from acidic to alkaline range,higher removal can be achieved.Temperature study demonstrates the endothermic nature of Ce3＋adsorption.The value of sticking probability suggests very high sticking probability of Ce3＋ ion for FRST nanoparticles.Ce3＋ uptake is favored by higher temperature and with the increase in temperature from298 to 328 K,Langmuir adsorption capacity increases from 36.45 to 42.99 m2/g.Applicability of FRST nanoparticles was also investigated for other light and heavy rare earth elements in single solute and multisolute systems,FRST nanoparticles show the significant removal of divalent metallic pollutants as well.The assessment of chemical toxicity of treated wastewater was carried out with the bioluminescent photobacterium（Vibrio fischeri） and decreased toxicity was observed in treated water samples.The outcome of present study suggests that the FRST nanoparticles can be efficiently utilized for the removal of Ce3＋ ions and a wide range of other pollutant species as well.

Export of dissolved carbonaceous and nitrogenous substances in rivers of the “Water Tower of Asia”

Rivers are critical links in the carbon and nitrogen cycle in aquatic,terrestrial,and atmospheric environments.Here riverine carbon and nitrogen exports in nine large rivers on the Tibetan Plateau—the＂Water Tower of Asia＂—were investigated in the monsoon season from 2013 to 2015.Compared with the world average,concentrations of dissolved inorganic carbon（DIC,30.7 mg/L）were high in river basins of the plateau due to extensive topographic relief and intensive water erosion.Low concentrations of dissolved organic carbon（DOC,1.16 mg/L）were likely due to the low temperature and unproductive land vegetation environments.Average concentrations of riverine DIN（0.32 mg/L）and DON（0.35 mg/L）on the Tibetan Plateau were close to the world average.However,despite its predominantly pristine environment,discharge from agricultural activities and urban areas of the plateau has raised riverine N export.In addition,DOC/DON ratio（C/N,~6.5）in rivers of the Tibetan Plateau was much lower than the global average,indicating that dissolved organic carbon in the rivers of this region might be more bioavailable.Therefore,along with global warming and anthropogenic activities,increasing export of bioavailable riverine carbon and nitrogen from rivers of the Tibetan Plateau can be expected in the future,which will possibly influence the regional carbon and nitrogen cycle.