Lipid peroxidation in the presence of iron oxides

Exposure to iron oxides dusts may lead to lung cancers among exposed population. To evaluate the involvement of iron‐containing particles in lipid peroxidation by production of reactive oxygen species, hematite, magnetite (iron oxides), and crocidolite (asbestos compound) were tested. The peroxidation was followed by the evaluation of some degradation products of lino‐lenic acid. In a buffered medium, magnetite is higher active than hematite. The addition of an iron chelator (EDTA) or of a reducing agent (ascorbate) in this medium enhances the activity of hematite and magnetite, and the combination of both EDTA and ascorbate increases their activity. Crocidolite is the most active whatever the medium. The appearance of the EDTA‐iron‐oxygen complexes related to the reactivity of these oxides is postulated. These results suggest that the oxidizing activity triggered by hematite and magnetite, in a medium containing an iron chelator and a reducing agent, may lead to damages in biological medium.     

Biotoxicity evaluation of zinc oxide nanoparticles on bacterial performance of activated sludge at COD,nitrogen, and phosphorus reduction

• ZnO-NP disrupted metabolic/catabolic balance of bacteria by affecting DHA activity. • ZnO-NPs toxicity was related to Zn²⁺ ion, interaction with cell and ROS generation. • Exposure to ZnO-NPs resulted in changed bacterial community structure at sludge. • The change in the EPS content was observed during exposure to ZnO-NPs. The unique properties and growing usage of zinc oxide nanoparticles increase their release in municipal wastewater treatment plants. Therefore, these nanoparticles, by interacting with microorganisms, can fail the suitable functioning of biological systems in treatment plants. For this reason, research into the toxicity of ZnO is urgent. In the present study, the toxicity mechanism of ZnO-NPs towards microbial communities central to granular activated sludge (GAS) performance was assessed over 120-day exposure. The results demonstrate that the biotoxicity of ZnO-NPs is dependent upon its dosage, exposure time, and the extent of reactive oxygen species (ROS) production. Furthermore, GAS performance and the extracellular polymeric substances (EPS) content were significantly reduced at 50 mg/L ZnO-NPs. This exposure led to decreases in the activity of ammonia monooxygenase (25.2%) and nitrate reductase (11.9%) activity. The Field emission scanning electron microscopy images confirmed that ZnO-NPs were able to disrupt the cell membrane integrity and lead to cell/bacterial death via intracellular ROS generation which was confirmed by the Confocal Laser Scanning Microscopy analysis. After exposure to the NPs, the bacterial community composition shifted to one dominated by Gram-positive bacteria. The results of this study could help to develop environmental standards and regulations for NPs applications and emissions.     

Semi-closed synthesis of nitrogen and oxygen Co-doped mesoporous carbon for selective aqueous oxidation

Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors, hard/soft templates, and heteroatom-containing agents. Herein, we report a facile synthesis of N and O co-doped meso/micro-porous carbon (NOMC) by template-free carbonization of a small-molecule precursor in a semi-closed system. The semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high yield. The porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular temperature. NOMCs as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with>85％conversion in aqueous solution, which is much higher than that of the control sample obtained in tube furnace (21％conversion), mainly due to their high N content, high percentage of pyridinic N, and large surface area. The presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous oxidation. The NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of>99％.     

低温对日本沼虾耗氧率、排氨率和Na+/K+ ATPase比活力的影响

在低温和室温条件下，测定了两种规格日本沼虾(Macrobrachium nipponens)的耗氧率、排氨率和Na^ ／K^ ATPase比活力．结果表明，低温条件下日本沼虾的耗氧率和排氨率均低于室温，且与体重呈负相关；而Na^ ／K^ ATPase比活力高于室温，且与体重呈正相关．表4参21     

生化需氧量测定的方法改进

生化需氧量测定中接种液的制备和稀释倍数的确定是2个关键的步骤,本文提出一种可行的制备接种液的方法,根据实践经验,总结出一种稀释倍数计算方法,适合在实际分析中使用。     

纳米光催化氧化测定不同水体化学需氧量的研究

采用简便的沉淀法制备的纳米氧化锌为光催化荆,重铬酸钾为光生电子接受体,研究了纳米氧化锌-重铬酸钾体系测定COD的方法.COD值在1～100mg/L之间有良好的线性关系,线性方程为y=0.0007χ 0.0069,相关系数为r=0.9992,检测限为0.66mg,L.采用本方法和CODM.国标法对不同水体样品进行比较测定发现,对低COD值样品本方法加标回收率在96.3%～100.6%之间,变异系数Cv%=1.1～3.4,准确度和精密度均优于CODMn国标法,弥补了低COD值样品国标法(CODmn)测定不准确的不足,且单个样品测定时间短,具有推广应用价值.     

Status and Trends of Dissolved Oxygen in Corpus Christi Bay, Texas, U.S.A.

The purpose of this studywas to determine status and long-term trends of dissolved oxygen concentrations (DO) in Corpus Christi Bay, Texas, U.S.A. A 20-year record of randomized stations was used to determine the trend of surface water DO, salinity, and temperature over space and time. A 13-year record of two fixed stations was used to determine the temporal nutrient trends. A 10-year record of fixed stations in the southeastern region of Corpus Christi Bay was used to determine the status of disturbance caused by low DO in bottom waters. From 1982 to 2002, there was a significant decrease in surface water DO at a rate of 0.06 mg L⁻¹ yr⁻¹ and a significant increase in surface water temperature at a rate of 0.07°C yr⁻¹. The southeastern region of Corpus Christi Bay had the lowest average DO, and during July and August, DO are steadily declining at a rate of 0.09 mg L⁻¹ yr⁻¹. It is not likely that eutrophication is causing hypoxia, because freshwater inflow rates have significantly decreased since 1941 and nutrient levels have not changed from 1987 to 2000. Even though long-term trends indicate that average surface DO is decreasing, disturbance by hypoxia appears to be stable, but this may be due to just eight years of data. In fact, if the current trend continues, surface water DO will not meet exceptional aquatic life standards (≤5 mgL⁻¹) in 2032.     

氧气和水蒸气对球状活性炭吸附SO2能力的影响

研究了Ｏ２和Ｈ２Ｏ对沥青基球状活性炭（ＰＳＡＣ）吸附ＳＯ２能力的影响。结果表明,Ｏ２和ＳＯ２占据不同的活性中心,而Ｈ２Ｏ和ＳＯ２占据同一类活性中心,且ＳＯ２与活性中心的结合能力比Ｈ２Ｏ强得多。Ｏ２或Ｈ２Ｏ均能提高ＰＳＡＣ对ＳＯ２的吸附能力。ＳＯ２吸附量的增加来源于ＳＯ２的化学吸附量。     

飞灰颗粒物介导活性氧氧化损伤与金属离子浸取浓度的关系研究

本文利用脱氧核糖氧化法考察了飞灰颗粒物氧化能力与络合剂及盐酸浸取颗粒物上金属浓度的关系。结果表明,代表氧化损伤程度指标的脱氧核糖氧化物,通过硫代巴比妥酸似丙二醛加合物显色反应,其吸光度值与飞灰颗粒物被浸取剂盐酸及氨三乙酸作用后的金属离子铁、锌、镉、铅和锰的浓度显著相关。基于铁在自然环境中的高含量及在活性氧催化反应中的特殊性,本文认为二乙三氨五乙酸、乙二胺四乙酸及柠檬酸浸取液中的金属浓度不能很好地表     

生物絮凝剂MBFGA1预处理乳制品加工废水

用生物絮凝剂MBFGA1预处理乳制品加工废水（简称废水）。实验结果表明,废水处理的水力条件为：以150r／min的转速搅拌30S,再以30r／min的转速搅拌20min;MBFGA1的最佳加入量为15mg／L;废水pH为4．0时,MBFGA1对废水的絮凝处理效果最好;废水温度对浊度、COD去除率有一定的影响,在20～45℃时,废水浊度的去除率始终保持在85％以上;30℃时,COD去除率达到最大值65．0％。