Effect of combined addition amount of nano zero-valent iron and biochar on methane production by anaerobic digestion of corn straw

Environment, Development and Sustainability - Anaerobic digestion (AD) is an attractive straw resource treatment technology as it can improve the utilization efficiency of straw resource. Raw straw...     

Effect of oxide nanoparticles on the morphology and fluidity of phospholipid membranes and the role of hydrogen bonds

Engineered oxide nanoparticles (NPs) are widely applied in insulators, catalyzers, paints, cosmetic products, textiles and semiconductors. Their attachment on cell membrane may lead to cytotoxicity. The effects of Al₂O₃, Fe₂O₃, SiO₂, TiO₂ and ZnO NPs on membrane integrity and fluidity were studied using giant or small unilamellar vesicles in this study. Al₂O₃ and SiO₂ NPs disrupted the oppositely charged membrane, indicating the important role of electrostatic attraction. However, Fe₂O₃, TiO₂ and ZnO NPs did not cause serious membrane disruption as Al₂O₃ and SiO₂ NPs. Membrane fluidity was evaluated by the generalized polarity (GP) values of Laurdan fluorescent emission. SiO₂ NPs induce the membrane gelation of both positively and negatively charged membrane. Al₂O₃ and ZnO NPs induced the gelation of the oppositely charged membrane, but did not cause obvious membrane gelation to the like charged membrane. The phospholipid molecular structural changes after NP exposure were analyzed by Fourier transform infrared (FT-IR) spectroscopy. FT-IR spectra revealed the hydrogen bond formation between NPs and the carbonyl/phosphate groups of phospholipids. Al₂O₃ and SiO₂ NPs showed strongest evidence of hydrogen bonding on their FT-IR spectra. It was consistent with the microscopic observation and fluorescent data that Al₂O₃ and SiO₂ NPs caused more serious membrane disruption and gelation. This study on membrane damage provides further knowledge on the cytotoxicity of nanomaterials and the safety of NP application.     

铁炭微电解强化水解酸化反应器高效处理聚乙烯醇废水

以聚乙烯醇(PVA)退浆废水为研究对象,构建了铁炭微电解强化厌氧生物处理的废水处理系统,对比研究了不同负荷条件下常规水解酸化反应器(R1,无铁炭材料)和铁炭耦合厌氧水解酸化反应器(R2,有铁炭材料)对PVA退浆废水的去除效果、颗粒污泥特性(胞外聚合物(EPS))、挥发性脂肪酸(VFAs)组成及微生物群落结构的差异。结果表明:R2出水平均COD去除率和平均PVA去除率分别稳定在86.8%和75.8%,均优于R1;添加铁炭材料可促进丙酸、丁酸转化成乙酸,提高了乙酸产量;R2颗粒污泥紧密黏附EPS(TB-EPS)、松散附着EPS(LB-EPS)含量较R1有所增加,颗粒污泥结构得到优化。高通量测序结果表明,添加铁炭对水解酸化菌群有显著影响,Propionibacteriaceae、Clostridium sensu stricto 12在PVA的降解中起重要作用。综合上述结果,铁炭微电解可有效强化水解酸化反应器对PVA退浆废水的处理效果,研究结果可为厌氧生物法处理PVA退浆废水提供参考。     

Response of extracellular and intracellular alkaline phosphatase in Microcystis aeruginosa to organic phosphorus

Environmental Science and Pollution Research - Cyanobacterial blooms caused by Microcystis have become a menace to public health and water quality in the global freshwater ecosystem. Alkaline...     

多目标优化方法在城市污水厂汇水区污染源总量控制规划中的应用

在城市污水处理厂汇水区实行污染源总量控制,应该避免与城市污水处理厂重复治理.针对这个问题,提出难降解有机物控制的多目标准则指标,建立了多目标优化模型.     

Particle size distribution and characteristics of heavy metals in road-deposited sediments from Beijing Olympic Park

Due to rapid urbanization and industrialization, heavy metals in road-deposited sediments(RDSs) of parks are emitted into the terrestrial, atmospheric, and water environment, and have a severe impact on residents' and tourists' health. To identify the distribution and characteristic of heavy metals in RDS and to assess the road environmental quality in Chinese parks, samples were collected from Beijing Olympic Park in the present study. The results indicated that particles with small grain size(150 μm) were the dominant fraction. The length of dry period was one of the main factors affecting the particle size distribution, as indicated by the variation of size fraction with the increase of dry days. The amount of heavy metal(i.e., Cu, Zn, Pb and Cd) content was the largest in particles with small size(150 μm) among all samples. Specifically, the percentage of Cu, Zn, Pb and Cd in these particles was 74.7%, 55.5%, 56.6% and 71.3%, respectively.Heavy metals adsorbed in sediments may mainly be contributed by road traffic emissions. The contamination levels of Pb and Cd were higher than Cu and Zn on the basis of the mean heavy metal contents. Specifically, the geoaccumulation index(I geo) decreased in the order:CdPbCuZn. This study analyzed the mobility of heavy metals in sediments using partial sequential extraction with the Tessier procedure. The results revealed that the apparent mobility and potential metal bioavailability of heavy metals in the sediments, based on the exchangeable and carbonate fractions, decreased in the order: CdZn≈PbCu.     

Ultrasonic-assisted synthesis of highly stable RuPd bimetallic catalysts supported on MgAl-layered double hydroxide for N-ethylcarbazole hydrogenation

Environmental Science and Pollution Research - N-Ethylcarbazole (NEC), as a promising liquid organic hydrogen carrier (LOHC), can store and release hydrogen through a reversible catalytic...     

The effect of different surface materials on runoff quality in permeable pavement systems

Environmental Science and Pollution Research - To investigate the effect of different permeable pavement surface materials on the removal of pollutants from urban storm-runoff, six commonly surface...     

2017年夏季巢湖水华期间浮游植物与蓝藻毒素的时空变化特征

蓝藻水华暴发过程中水华物种的演替及其与蓝藻毒素的关系，对于湖泊的风险评估具有重大意义。于2017年水华暴发较为严重的夏季（6-8月）对巢湖水体的理化参数、浮游植物和蓝藻毒素进行了调查和分析。结果表明：夏季巢湖基本上处于富营养-超富营养的状态。24个样本共鉴定出浮游植物7门72属117种，以绿藻门、蓝藻门和硅藻门为主。浮游植物的群落组成和细胞密度存在明显的时空差异性，其中6月浮游植物平均细胞密度为1.35×10⁸ cells/L，优势种属主要为微囊藻（Microcystis spp.，优势度为0.397）、水华长孢藻（Dolichospermum flos-aquae，优势度为0.195）和水华束丝藻（Aphanizomenon flos-aquae，优势度为0.181）；7月浮游植物平均细胞密度为1.31×10⁸ cells/L，优势种属主要为微囊藻（优势度为0.741）和黏伪鱼腥藻（Pseudanabaena mucicola，优势度为0.072）；8月浮游植物平均细胞密度为1.01×10⁸ cells/L，优势种属主要为微囊藻（优势度为0.646）。11种蓝藻毒素在夏季巢湖水体中均有不同程度的检出，其中以微囊藻毒素MC-LR、MC-RR和MC-YR为主，最高检出浓度分别为0.115、0.107、0.018 μg/L。此外，分析了拟柱孢藻毒素浓度与水华束丝藻细胞密度的关系，显示两者之间存在非常显著的正相关性（P<0.01），表明水华束丝藻可能是其最主要的产毒蓝藻。11种蓝藻毒素的浓度均未超过饮用水安全标准的规定，但其潜在的安全风险依然需要密切注意。     

酸雨对生菜的光合、抗氧化系统和产量的影响研究

目前国内外有关酸雨对植物生长危害的影响研究多集中在森林植物和粮食作物,而酸雨对叶菜类蔬菜生长的相关研究较少。酸雨的频发可能会影响蔬菜的生长,进而降低蔬菜产量。为探究酸雨对叶菜类蔬菜生理和产量的影响,选取生菜(Lactuca sativa L.var.ramosa Hort.)作为试验材料,采用野外原位研究方法,探究模拟酸雨(pH梯度为3.0、4.0、5.0)和自然降水(CK)对生菜光合、抗氧化系统和产量的影响。结果表明,pH 4.0和5.0酸雨对生菜光合系统影响不显著,pH 3.0酸雨对生菜光合系统影响显著;在整个试验期内,pH 3.0酸雨显著降低生菜净光合作用8.4%—17.0%。pH 3.0、4.0和5.0酸雨均显著提高生菜超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,表明酸雨会激活生菜抗氧化系统,同时会对生菜叶片膜系统造成损伤;在第20天后,pH 3.0酸雨下生菜过氧化氢酶(CAT)活性显著下降13.8%%—35.2%。pH 5.0酸雨对生菜产量影响不显著;pH 4.0和3.0酸雨显著降低生菜地上部产量,分别降低14.6%和16.7%。pH 3.0酸雨使生菜地下部产量显著降低19.0%。综上可见,模拟酸雨对生菜的光合系统、抗氧化酶系统和产量均产生显著影响,且酸雨对生菜的影响阈值在pH 4—5之间,pH 4.0以下的酸雨明显降低生菜产量,但酸雨强度为pH 5.0时已存在生菜减产的风险,研究结果可为生菜栽培的相关农户以及决策部门提供参考。