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81.
Yongguang Yin Xiaoya Yang Xiaoxia Zhou Weidong Wang Sujuan Yu Jingfu Liu Guibin Jiang 《环境科学学报(英文版)》2015,27(8):116-125
The inevitable release of engineered silver nanoparticles (AgNPs) into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of AgNPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered AgNPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone (PVP) coated AgNPs was investigated in eight typical environmental water samples (with different ionic strengths, hardness, and dissolved organic matter (DOM) concentrations) by using UV–visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of AgNPs. Further, the photo-transformation and morphology changes of AgNPs in environmental waters were studied by UV–visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes (especially Ca2 + and Mg2 +) and DOM in the surface waters are key parameters for AgNP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of AgNPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of AgNPs in the aquatic environments. 相似文献
82.
83.
采用Fe3O4活化过硫酸盐(PS)同步去除水中的NOR (诺氟沙星)和Pb (II).探讨了Fe3O4投加量、PS浓度、初始pH值和Pb (II)浓度对NOR降解的影响.结果表明,NOR的降解符合伪一级反应动力学,在温度为30℃、NOR初始浓度为5.0mg/L、Pb (II)浓度为1.0mg/L、Fe3O4投加量为2.0g/L、PS浓度为1.5mmol/L、初始pH值为7.0的条件下,反应120min后,NOR降解率达90.2%,Pb (II)去除率为99.5%.自由基淬灭实验证实,硫酸根自由基(SO4-·)是NOR降解的主要自由基.通过LC-MS分析结果推测了NOR可能的降解路径和中间产物.Fe3O4活化PS高级氧化工艺可作为一种同步去除有机污染物和重金属的工艺. 相似文献
84.
由于大量人类活动的影响,大气CO_2浓度持续增加,其中约1/3被海洋吸收,导致表层海水pH值降低和碳酸盐平衡体系波动,即"海洋酸化"现象。污染物的海洋环境效应一直是全球环境科学领域研究的热点。在实际环境中,海洋酸化往往与污染物共同存在并作用于海洋生态系统,且海洋酸化极有可能改变污染物的海洋环境行为从而影响其毒性效应。但现有研究大多针对海洋酸化或者污染物单独作用下的毒性效应展开,对海洋酸化与污染物的联合毒性效应的研究不足、亟待加强。为此,综述了近年来海洋酸化与典型污染物(重金属、有机污染物)及新型污染物(人工纳米颗粒)的相关文献,重点阐述了海洋酸化对污染物环境行为的影响和海洋酸化与污染物对海洋生物的联合毒性效应,指出当前的研究不足,并对未来的研究方向进行了展望。 相似文献
85.
OMS-2 nanorod catalysts were synthesized by a hydrothermal redox reaction method using MnSO4 (OMS-2-SO4) and Mn(CH3COO)2 (OMS-2-AC) as precursors. SO42 −-doped OMS-2-AC catalysts with different SO42 − concentrations were prepared next by adding (NH4)2SO4 solution into OMS-2-AC samples to investigate the effect of the anion SO42 − on the OMS-2-AC catalyst. All catalysts were then tested for the catalytic oxidation of ethanol. The OMS-2-SO4 catalyst synthesized demonstrated much better activity than OMS-2-AC. The SO42 − doping greatly influenced the activity of the OMS-2-AC catalyst, with a dramatic promotion of activity for suitable concentration of SO42 − (SO4/catalyst = 0.5% W/W). The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP-OES), NH3-TPD and H2-TPR techniques. The results showed that the presence of a suitable amount of SO42 − species in the OMS-2-AC catalyst could decrease the Mn–O bond strength and also enhance the lattice oxygen and acid site concentrations, which then effectively promoted the catalytic activity of OMS-2-AC toward ethanol oxidation. Thus it was confirmed that the better catalytic performance of OMS-2-SO4 compared to OMS-2-AC is due to the presence of some residual SO42 − species in OMS-2-SO4 samples. 相似文献
86.
87.
华北平原玉米-小麦轮作农田N2O交换通量的研究 总被引:6,自引:2,他引:6
以华北地区冬小麦-夏玉米轮作农田为研究对象,运用静态箱法对正常施肥及正常施肥结合秸秆还田农田N2O交换通量进行了连续1 a对比研究.正常施肥及正常施肥结合秸秆还田样地N2O全年的累积排放量分别为7.61 kg.hm-2和12.6kg.hm-2,其中秸秆还田引起N2O排放明显增加主要发生在玉米生长季节.两种处理样地在玉米季N2O的排放量占全年累积排放的57%~86%,表明华北玉米-小麦轮作体系中N2O排放主要集中在玉米季.各次施肥后10 d内N2O的累积排放量约占全年总排放量的71%~88%,显然现有化肥极大促进了华北农田N2O排放. 相似文献
88.
Lei Shen Yuntao Guan Guangxue Wu Xinmin Zhan 《Frontiers of Environmental Science & Engineering》2014,8(5):776-783
Nitrous oxide (N2O) is a greenhouse gas that can be released during biological nitrogen removal from wastewater. N2O emission from a sequencing batch reactor (SBR) for biological nitrogen and phosphorus removal from wastewater was investigated, and the aims were to examine which process, nitrification or denitrification, would contribute more to N2Oemission and to study the effects of heterotrophic activities on N2O emission during nitrification. The results showed that N2O emission was mainly attributed to nitrification rather than to denitrification. N2O emission during denitrification mainly occurred with stored organic carbon as the electron donor. During nitrification, NaO emission was increased with increasing initial ammonium or nitrite concentrations. The ratio of N2O emission to the removed ammonium nitrogen (N2O- N/NH4-N) was 2.5% in the SBR system with high heterotrophic activities, while this ratio was in the range from 0.14% to 1.06% in batch nitrification experiments with limited heterotrophic activities. 相似文献
89.
90.
Ana L. De Toffoli Bruno H. Fumes 《Journal of environmental science and health. Part. B》2018,53(7):434-440
On-line in-tube solid phase microextraction (in-tube SPME) coupled to high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) was successfully applied to the determination of selected triazines in water samples. The method based on the employment of a packed column containing graphene oxide (GO) supported on aminopropyl silica (Si) showed that the extraction phase has a high potential for triazines extraction aiming to its physical-chemical properties including ultrahigh specific surface area, good mechanical and thermal stability and high fracture strength. Injection volume and loading time were both investigated and optimized. The method validation using Si-GO to extract and concentrate the analytes showed satisfactory results, good sensitivity, good linearity (0.2–4.0 µg L?1) and low detection limits (1.1–2.9 ng L?1). The high extraction efficiency was determined with enrichment factors ranging from 1.2–2.9 for the lowest level, 1.3–4.9 intermediate level and 1.2–3.0 highest level (n = 3). Although the analytes were not detected in the real samples evaluated, the method has demonstrated to be efficient through its application in the analysis of spiked triazines in ground and mineral water samples. 相似文献