磁性壳聚糖/膨润土复合吸附剂吸附Cu2+

以膨润土、壳聚糖、Fe3O4为原料,制备了在外加磁场作用下能实现快速固液分离的磁性壳聚糖/膨润土复合吸附剂.利用SEM、XRD、VSM、FTIR等分析手段对复合吸附剂的形貌及微观结构进行了表征.通过静态吸附实验研究了复合吸附剂对Cu2+的吸附性能,探讨了溶液初始pH值、吸附剂投加量、吸附时间和吸附温度等对Cu2+吸附效果的影响.结果表明,壳聚糖和Fe3O4均已负载到膨润土上.复合吸附剂吸附Cu2+的效果随溶液pH值和吸附剂投加量的增加而增加,并最终趋于稳定;当吸附剂投加量为7.2 g/L、pH值为6、Cu2+初始浓度为30 mg/L时,Cu2+的去除率可达98.5%.吸附动力学和吸附等温线数据分别较好地符合准二级动力学模型和Langmiur吸附等温模型.热力学参数表明,吸附是自发、吸热的过程.     

Tetracycline resistance in semi-arid agricultural soils under long-term swine effluent application

Annually, millions pounds of antibiotics are released unmetabolized into environment along with animal wastes. Accumulation of antibiotics in soils could potentially induce the persistence of antibiotic resistant bacteria. Antibiotics such as tetracyclines and tetracycline-resistant bacteria have been previously detected in fields fertilized with animal manure. However, little is known about the accumulation of tetracyclines and the development of tetracycline resistance in semi-arid soils. Here we demonstrate that continuous land application with swine effluent, containing trace amounts of chlortetracycline, does not necessarily induce tetracycline resistance in soil bacteria. Based on the testing of more than 3,000 bacteria isolated from the amended soils, we found no significant increase in the occurrence and level of chlortetracycline resistant bacteria in soils after 15 years of continuous swine effluent fertilization. To account for a possible transfer of tetracycline-resistant bacteria originated from the swine effluent to soils, we analyzed two commonly found tetracycline resistant genes, tet(O) and tet(M), in the swine effluent and fertilized soils. Both genes were present in the swine effluent, however, they were not detectable in soils applied with swine effluent. Our data demonstrate that agronomic application of manure from antibiotic treated swine effluent does not necessarily result in the development of antibiotic bacterial resistance in soils. Apparently, concentrations of chlortetracycline present in manure are not significant enough to induce the development of antibiotic bacterial resistance.     

Population structure and phylogeography of an acorn barnacle with induced defense and its gastropod predator in the Gulf of California

Using sequence variation in the mitochondrial cytochrome oxidase I locus, we estimated the population structure and phylogeography of the intertidal acorn barnacle, Chthamalus anisopoma, and its gastropod predator, Mexacanthina lugubris angelica. Both are endemic to the Gulf of California, being derived from taxa on the Pacific coast of the Baja peninsula, and both exhibit phenotypic plasticity for traits affecting their coevolutionary interactions. Consistent with expectations based on differences in dispersal, C. anisopoma populations generally lack geographic structure, while those of M. l. angelica are more strongly structured. However, the variable degree of differentiation in both species suggests that the extent of reciprocal selection and local adaptation in the species will vary geographically, a result consistent with the concept of a geographic mosaic of coevolution. The pattern of variation in C. anisopoma shows clear evidence of recent spatial expansion, possibly due to increased habitat availability following the last glacial maximum. Phylogeographic analyses suggest that M. l. angelica diversified into three distinct clades after the colonization of the Gulf. Overall, our results illustrate how dispersal potential, geological and climatic events, and recent population growth have impacted the pattern of sequence variation in the two species.     

退化滨水景观带植物群落生态修复技术研究进展

滨水带是重要的生态交错带,物质、养分和能量流动速率高,具有较高的生态、经济和美学价值。近年来,由于缺乏科学合理的生态规划意识,我国滨水带多被建成近直立人工护岸,加之自然、人为干扰力度的加强,滨水岸线生境破坏,生物群落丧失,滨水带退化,水岸生态环境日趋恶化。通过对滨水带生态景观功能分析,研究滨水带退化原因与机理,系统归纳了国内外退化滨水景观带植物群落生态修复相关技术的研究现状,深入探讨了生境恢复、生物廊道恢复、景观格局美化和水岸生态系统结构与功能优化等方面的研究内容,并提出今后滨水带生态修复技术研究方向,以及基于生态学、景观学、水力学、土力学、生物学、经济学等多学科背景的滨水景观带植物群落定量分析、配置方法。最后指出,滨水景观带植物群落生态修复技术研究需进一步分析我国水岸生态系统退化机理、细化滨水深槽-浅滩序列、量化滨水植被配置宽度与生物多样性关系、深化稳定化长效管理技术等,为我国退化滨水生态景观带植物群落生态修复集成技术的研究与实践提供参考,以全面有效的提高生态环境质量。     

Effect of co-existing organic compounds on adsorption of perfluorinated compounds onto carbon nanotubes

Co-existing organic compounds may affect the adsorption of perfluorinated compounds (PFCs) and carbon nanotubes in aquatic environments. Adsorption of perfluorooctane sulfonate (PFOS), perfluorooctane acid (PFOA), perfluorobutane sulfonate (PFBS), and perfluorohexane sulfonate (PFH_xS) on the pristine multi-walled carbon nanotubes (MWCNTs-Pri), carboxyl functionalized MWCNTs (MWCTNs-COOH), and hydroxyl functionalized MWCNTs (MWCNTs-OH) in the presence of humic acid, 1-naphthol, phenol, and benzoic acid was studied. Adsorption kinetics of PFOS was described well by the pseudo-second-order model and the sorption equilibrium was almost reached within 24 h. The effect of co-existing organic compounds on PFOS adsorption followed the decreasing order of humic acid>1-naphthol>benzoic acid>phenol. Adsorbed amounts of PFOS decreased significantly in the presence of co-existing or preloaded humic acid, and both adsorption energy and effective adsorption sites on the three MWCNTs decreased, resulting in the decrease of PFOS adsorption. With increasing pH, PFOS removal by three MWCNTs decreased in the presence of humic acid and phenol. The adsorbed amounts of different PFCs on the MWCNTs increased in the order of PFBSxS相似文献   

珠江隧道多环芳烃的含量与分布特征

为研究机动车尾气排放多环芳烃的排放特征,以及其从源到汇的过程变化,该研究选取珠江隧道为研究区域,采集了2006年4月、7月和12月珠江隧道中气相和颗粒相样品,以及7月、12月份隧道附近的大气样品,并对样品中多环芳烃(PAHs)进行检测.结果表明,隧道中馪AHs范围为896.1 ng·m-3～4066.2 ng·m-3,气相中馪AHs远远高于颗粒相馪AHs.环境大气样品中馪AHs为207.9 ng·m-3～353.0 ng·m-3,远远低于隧道里馪AHs,其PAHs各组分的分布特征与隧道中样品相似,说明汽车尾气是广州市大气中PAHs的重要来源;最后通过隧道中与隧道口的馪AHs来计算汽车的排放因子,得出PAHs排放因子平均值为:2164.7 靏穔m-1妨,并且估算出2006年广州市全年汽车尾气排放出PAHs 82 t.     

土壤中乐果与微生物的相互作用研究

采用室内模拟实验,研究了土壤中乐果与微生物的相互作用.结果表明:(1)50、500、5 000 mg·kg-1的乐果在灭菌土中的降解速度十分缓慢,加药后15d,50 mg·kg-1的降解率为69.3%,500 mg·kg-1的降解率为26.7%,5 000 mg·kg-1的降解率为19.6%.在施过乐果的土壤中的降解速度非常迅速,加药后15d,50 mg·kg-1的降解率为99.7%,500 mg·kg-1的降解率为78.4%,5 000 mg·kg-1的降解率为54.6%.在未施过乐果的土壤中的降解速度则介于二者之间.说明微生物在乐果的降解中起着非常重要的作用,同时,施药可以诱发乐果降解菌的生成从而加速乐果的降解.(2)在各处理的土壤中,50 mg·k-1的乐果对细菌数星有一定的刺激作用,500、5 000 mg·kg-1的乐果抑制细菌的生长.且随质量浓度的升高,抑制作用增强.但随加药时间的延长,又有所恢复.3种不同质量浓度的乐果对土壤真菌和放线菌种群数量的影响均表现为明显的抑制作用,且随药剂质量浓度的提高和加药时间的延长抑制趋势越明显.因此,可以选择真菌和放线菌作为土壤受乐果污染的敏感指示菌.(3)在同样处理条件下,施过乐果土壤中的微生物种群数量并不比未施过乐果土壤中的占优势,表明乐果在施过药的土壤中降解速度的加快并不是由微生物的数量决定的,而是由它们的降解能力决定的.     

高压静电处理水对活性污泥耗氧速率的影响研究

利用活性污泥微生物膜制成ＢＯＤ生物传感器,发现在经过一定时间高压静电处理后的缓冲液中,活性污泥降解有机物的能力可提高２０％以上,同一电压不同处理时间对微生物降解影响不同。处理时间过短或过长对微生物降解能力增加的影响都不明显,不同电压达到良好处理效果所需时间不同,较低电压所需时间较长,５０００Ｖ时约需６．０ｈ（信号响应达到初始值的１２４％）,而７０００Ｖ时约为４．０ｈ,结果表明,高压静电处理并接种活     

Formation of halonitromethanes from methylamine in the presence of bromide during UV/Cl2 disinfection

The UV/Cl₂ process is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of high-toxic halonitromethanes (HNMs) in the presence of bromide ions (Br⁻) during UV/Cl₂ disinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br⁻. An excessively high concentration of Br⁻ induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor (BIF) increased, while the maximum bromine utilization factor (BUF) decreased with the increase of Br⁻ concentration. The maximum yield of HNMs decreased as pH value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while pH value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl₂:Br⁻ ratio of 12.5, whereas the BIF value remained relatively higher at low Cl₂:Br⁻ ratios (2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon. Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation (especially brominated species) when the UV/Cl₂ process is adopted as a disinfection technique.     

Processing of copper converter slag for metals reclamation: Part II: mineralogical study.

Chemical and mineralogical characterizations of a copper converter slag, and its products obtained by curing with strong sulphuric acid and leaching with hot water, were carried out using ore microscopy, scanning electronic microscopy with energy dispersive spectrometry, wave-length dispersive X-ray fluorescence spectrometry, X-ray diffractometry and chemical phase analysis, which provided necessary information to develop a new process for treating such slag and further understanding of the chemical and mineralogical changes in the process.