Biosorption of copper and zinc by immobilised and free algal biomass, and the effects of metal biosorption on the growth and cellular structure of Chlorella sp. and Chlamydomonas sp. isolated from rivers in Penang, Malaysia

In this study, the biosorption of copper and zinc ions by Chlorella sp. and Chlamydomonas sp. isolated from local environments in Malaysia was investigated in a batch system and by microscopic analyses. Under optimal biosorption conditions, the biosorption capacity of Chlorella sp. for copper and zinc ions was 33.4 and 28.5 mg/g, respectively, after 6 hr of biosorption in an immobilised system. Batch experiments showed that the biosorption capacity of algal biomass immobilised in the form of sodium alginate beads was higher than that of the free biomass. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that copper and zinc were mainly sorbed at the cell surface during biosorption. Exposure to 5 mg/L of copper and zinc affected both the chlorophyll content and cell count of the algal cells after the first 12 hr of contact time.     

纳米TiO_2/Nafion修饰金电极溶出伏安法测量痕量铜

利用纳米二氧化钛(nano-TiO2)的结构特性,采用滴涂法制备了一种nano-TiO2/Nafion修饰金电极,采用差分脉冲溶出伏安法实现了水样中痕量铜的检测。详细研究了Cu2+在nano-TiO2/Nafion修饰金电极上的电化学响应行为,并讨论了nano-TiO2/Nafion膜的厚度、溶液pH值、富集电位、富集时间等对Cu2+溶出峰电流的影响。实验结果表明:在pH=2.0硝酸溶液中,-0.5 V恒电位搅拌富集240 s,静置10 s后阳极化扫描,Cu2+在0.25 V左右出现阳极溶出峰。相比于裸金电极,该峰电流大大提高,表明nano-TiO2对Cu2+的溶出具有一定的增敏作用。在最优化实验条件下,10~900 nmol/L范围内,Cu2+的溶出峰电流与其浓度呈良好的线性关系,检出限可达3.2 nmol/L。该修饰电极具有一定的抗干扰能力,将其应用于国标样品和实际自来水样中Cu2+的检测,结果令人满意。     

常见金属及金属氧化物催化超声降解间苯二酚

探索了以常见金属铜、锌、铝单质及其氧化物为催化剂,提高超声降解间苯二酚速率的可行性。在超声/零价金属以及超声/金属氧化物同时存在的条件下,以间苯二酚为目标污染物,对间苯二酚的去除效果、溶液pH的变化及金属离子的溶出等进行考察,并对超声波与金属以及金属氧化物协同催化降解有机物的作用机理进行了初步的探讨。实验结果表明,铜、锌、氧化铜均可以有效地催化间苯二酚的超声降解,其过程均符合假一级动力学反应。各类金属和金属氧化物的催化能力排序为铜、锌混合物>氧化铜、锌混合物>锌>铜≈氧化铜。当间苯二酚初始浓度为0.05 mmol/L,初始pH=5,超声频率25 kHz,功率为200 W,铜、锌比例为1:1,投量为1 g/L时,US/Cu-Zn去除间苯二酚的速率常数为1.53×10-2min-1,是单独超声作用时的9倍。     

Phytoavaelability and extractability of copper and zinc in calcareous soil amended with composted Urban wastes

Abstract

A greenhouse experiment was conducted under simulated field conditions using large‐capacity plastic pots, filled each one with 25 kg of air‐dried calcareous soil. Besides the control, four treatments were prepared by applying separately two rates (20 and 80 Mg ha^‐1) of municipal solid waste (MSW) compost, and co‐composted municipal solid waste and sewage sludge (MSW‐SS). Lettuce was planted and harvested 2.5 months later. The application of composted urban wastes tended to increase Cu concentration in lettuce with respect to the control, but it was only significant when the higher rate of MSW compost was applied. The control showed values of Zn concentration in plant within a deficient range. In general, composted urban wastes treatments had increased Zn concentration values, which were within the sufficiency range. Both treatments with MSW compost increased Cu and Zn uptake in comparison with MSW‐SS co‐compost treatments. At the postharvest, all composted urban wastes treatments increased significantly DTPA‐extractable Cu content in soil with respect to the control; it was also significant the increase in AAAc‐EDTA‐extractable Cu in soil produced by the addition of the higher rate of MSW compost. The application of composted urban wastes increased significantly DTPA‐extractable and AAAc‐EDTA‐extractable Zn contents in soil versus the control, except for the lower rate of MSW‐SS co‐compost. The values of DTPA‐extractable/total ratio for Cu and Zn were under 10%, except for the treatment applying the higher rate of MSW compost which promoted higher values. The values of AAAc‐EDTA‐extractable/total ratio for Cu were above 10% in all treatments including the control. This tendency was also observed in AAAc‐EDTA‐extractable/total ratio for Zn when applying both rates of MSW compost or the higher rate of MSW‐SS co‐compost.     

多因子影响下铜的水质基准及生态风险

为探究特定水环境中多因子影响下的铜水质基准及生态风险,采用物种权重敏感度分布法、水效应比法和生物配体模型推导保护太湖水生生物铜的水质基准.根据推导结果,推荐采用最大浓度基准值(CMC)1.43 μg/L和持续浓度基准值(CCC)1.33 μg/L.结合水效应比法和生物配体模型,采用联合概率法评估太湖铜的生态风险.结果表明,两种方法下丰水期5%水生生物受到铜慢性毒性影响的概率分别为23.43%和39.43%,而未考虑多因子影响的风险概率为85.01%,高估了太湖铜生态风险.可见,水环境多因子对水质基准和生态风险的影响不容忽视,我国目前使用的铜标准可能无法保护特定区域的水生生物.考虑多因子影响可提高基准值推导和风险评估的科学性,避免"过保护"和"欠保护"现象.     

硝酸根电化学还原去除过程阴极电位振荡研究

硝酸根在电化学还原去除过程中存在多价态变化行为,该过程是一个典型的远离平衡态的非线性体系.为探明硝酸根在去除过程中发生的电化学行为,研究了H₂SO₄浓度、电流、反应温度及NO₃^-浓度对阴极电位振荡的影响规律.采用循环伏安法、XRD、SEM-EDS及XPS表征方法,分析了反应体系循环伏安特性,以及反应前后阴极Cu表面的物相组成、微观形貌、表面电子价态等变化规律.研究结果表明,在恒流条件下(Pt作为阳极、Cu作为阴极),H₂SO₄-NaNO₃体系发生了明显的电位振荡;当H₂SO₄浓度为0.10mol/L,电流为12mA,温度为20℃,NaNO₃浓度为0.20mol/L最佳电位振荡条件下,振荡平均振幅为1.15V,振荡平均周期为3s.另外,硝酸根在电化学还原去除过程产生的周期性电位振荡主要原因是阴极Cu表面生成的致密CuO薄膜不断溶解和形成,以及阴极表面H₂的周期性产生与消失.     

铜镉胁迫对2种菌根真菌生长和细胞壁离子交换量的影响

在离体培养条件下,研究了铜镉胁迫对2种外生菌根真菌美味牛肝菌(Boletus edulis)和铆钉菇(Gomphidius viscidus)生长状况,培养环境pH值和细胞壁离子交换量的影响.结果表明,以对照相比,铜镉处理抑制了菌根真菌的生物量积累.通过半致死浓度评价2种菌根真菌耐受性发现,铆钉菇的Cu耐受性强于美味牛肝菌,而Cd耐受性弱于美味牛肝菌.菌根真菌培养后,基质pH降低与真菌生物量有关.铜镉处理下菌根真菌单位生物量下降的pH单位大于对照,说明菌根真菌在重金属胁迫下能通过调节自身pH环境缓解压力.铆钉菇的离子交换量在780～1 800μmol·g^-1之间,并随重金属处理浓度的增加而增加;美味牛肝菌的离子交换量在500～750μmol·g^-1之间,并随重金属处理浓度的增加而减少.     

AN IN SITU COMPARISON OF THE EFFECTIVENESS OF FOUR ALGICIDES1

ABSTRACT: Four algicides (copper citrate, copper ethanolamine, simazine, and diuron) were tested for effectiveness using in situ bio-assays. Bioassays were conducted in clear polyethylene bags and algicide effectiveness measured by chlorophyll a, productivity, and algal counts. The body of water where this testing took place had a high pH (9.2), and high levels of total dissolved solids (610 mg/l) and nutrients. The order of effectiveness found in this study was simazine > diuron > copper ethanolamine > copper citrate.     

Fenton氧化-混凝联合工艺处理络合铜镍废水的研究

采用Fenton试剂氧化-混凝联合工艺对难处理络合铜镍电镀废水进行了研究,考察了废水初始pH值、H2O2初始浓度、[Fe2 ]/[H2O2]、反应时间和温度、混凝液pH、混凝剂质量浓度对处理过程的影响,探讨了废水的降解途径和机理.结果表明,在体系初始pH=4,温度30℃,H2O2投加量为800mg/L,[Fe2 ]/[H2O2]=0.1,反应时间60 min,混凝液pH=8及混凝剂质量浓度为500mg/L的条件下,废水的COD去除率为96.98%,Cu2 为99.91%,Ni2 为99.92%,处理水完全达到国家一级排放标准.同时依据GC/MS对X-GN降解最终产物的分析结果,推导出废水的基本降解机理和途径.     

Species of copper and zinc in sediments collected from the antarctic ocean and the Taiwan Erhjin Chi coastal area

The species of copper and zinc, such as bioexchangeable, skeletal, easily reducible (Fe and Mn oxides), moderately reducible (crystalline Mn oxide), organic combined with sulfides, and detritus with minerals, in mud and sand, separated from the surface Antarctic Ocean and the Taiwan Erhjin Chi coastal (including river and estuarine) sediments, have been analyzed by sequential leaching methods. Results show that in the Antarctic Ocean sediments, high concentrations of total copper (128 mg/kg) and zinc (458 mg/kg) were found in the high mud (99.09%) content samples compared with the low concentrations of total copper (83.8 mg/kg) and zinc (288 mg/kg) in low mud (51.69%) content samples. High concentrations of copper, zinc, manganese and iron are possibly due to the characteristics of manganese nodules, in which the species of copper and zinc are mainly contained in the crystalline Mn oxide phase. In the Taiwan Erhjin Chi coastal sediments, the total copper and zinc concentrations in mud and sand vary with season and location. High values were generally observed in the river sediments during the dry season, and low values were in the estuarine and coastal sediments during the heavy rainy season. High percentages of copper (as high as 49.4%) and zinc (as high as 76.7%) in mud and sand were in the bioexchangeable phase including the skeletal phase. This result might be correlated with the problems arising from human impact on copper and zinc as well as sewage pollution in Taiwan. In the organic combined phase, biogenic particulate matter related to higher primary productivity in the Antarctic Ocean is also discussed.