Stability of Fe–As composites formed with As(V) and aged ferrihydrite

During the aging process, ferrihydrite was transformed into mineral mixtures composed of different proportions of ferrihydrite, goethite, lepidocrocite and hematite. Such a transformation may affect the fixed ability of arsenic. In this study, the stability of Fe-As composites formed with As(V) and the minerals aged for 0, 1, 4, 10 and 30 days of ferrihydrite were systematically examined, and the effects of molar of ratios Fe/As were also clarified using kinetic methods combined with multiple spectroscopic techniques. The results indicated that As(V) was rapidly adsorbed on minerals during the initial polymerization process, which delayed both the ferrihydrite conversion and the hematite formation. When the Fe/As molar ratio was 1.875 and 5.66, the As(V) adsorbed by ferrihydrite began to release after 6 hr and 12 hr, respectively. The corresponding release amounts of As(V) were 0.55 g/L and 0.07 g/L, and the adsorption rates were 92.43% and 97.50% at 60 days, respectively. However, the As(V) adsorbed by the transformation products aged for 30 days of ferrihydrite began to release after adsorbed 30 days. The corresponding release amounts of As(V) were 0.25 g/L and 0.03 g/L, and the adsorption rates were 84.23% and 92.18% after adsorbed 60 days, for the Fe/As=1.875 and 5.66, respectively. Overall, the combination of As(V) with ferrihydrite and aged products transformed from a thermodynamically metastable phase to a dynamically stable state within a certain duration. Moreover, the aging process of ferrihydrite reduced the sorption ability of arsenate by iron (hydr)oxide but enhanced the stability of the Fe-As composites.     

Expression and functional analysis of three nicosulfuron-degrading enzymes from Bacillus subtilis YB1

To investigate the degradation activity of the manganese ABC transporter, vegetative catalase 1 and acetoin dehydrogenase E1 from Bacillus subtilis YB1, the proteins were prokaryotically expressed and purified. Assay results showed that the three enzymes were able to degrade nicosulfuron (2- (4,6-dimethoxypyrimidine-2-pyrimidinylcarbamoylaminosulfonyl) -N,N-dimethylnicotinamide), with vegetative catalase 1 exhibiting the highest activity. To further examine the degradation pathway, the degradation products of the three enzymes and the YB1 strain were detected by liquid chromatography-mass spectrometry(LC-MS). The nicosulfuron degradation products of the three enzymes were consistent with those of the YB1 strain, indicating the presence of two pathways: one due to cleavage of sulfonylurea bridges and ring-opening of 1-(4,6-dimethoxy-pyrimidin-2-yl)-3-(2-methyliminomethanesulfonyl-acetyl)-ureaas the pyrimidine ring, yielding the product; and the another due to cleavage of a sulfonylurea bridge, yielding 4,6-dihydroxy pyrimidine (111 m/z), 2-ylamine ?4,6-dimethoxy pyrimidine and ((4-(dimethycarbamoyl)pyridine-2-yl)sulfonyl)carbamic acid as products, which were further degraded to 4,6-dihydroxy pyrimidine and N,N-dimethyl-2-sulfamoyl-isonicotinamide. The above results reveal a major contribution of extracellular enzymes to the degradation of nicosulfuron by the YB1 strain. Our data help in elucidation of the mechanism of nicosulfuron bio-degradation and may facilitate the construction of engineered strains.     

城市污水中有关新型微污染物PPCPs归趋研究的进展

药品和个人护理用品 (PPCPs) 是最近十年引起关注的新型有机微量污染物,其引起的环境安全风险受到人们越来越多的关注。一些研究发现,城市污水处理厂出水中存在着一定浓度的PPCPs,城市污水排放是PPCPs进入环境的一条重要途径。从城市污水中PPCPs的分析方法、迁移转化和减量化技术研究等三个方面综述了有关PPCPs在城市污水中归趋的研究进展,介绍了我国城市污水中PPCPs的研究现状;并对在我国进行相关研究提出了建议,以期推动相关研究的开展。     

低碳农业对农产品安全的影响研究

针对我国现代农业、农产品生产及安全的现状,深入分析高碳农业对农产品安全的危害,阐述低碳农业与农产品安全的关系,探讨低碳农业对农产品安全的保障机理,探索发展低碳农业、保障农产品安全实现的途径。通过对英国、美国以及国内有机农业实践的研究,指出保障农产品安全的关键因素是将农业的生态系统和经济系统结合起来,减少以化石燃料为基础的要素投入,提高农业系统生产力。该研究成果对加快转变农业发展模式,实现农业可持续发展,降低农产品的安全隐患具有一定的理论指导和实践参考价值。     

The application of an indicator based on taxonomic distinctness for UK marine biodiversity assessments

Mankind needs to use the resources and opportunities offered by the marine environment while protecting ecological processes and systems. This is the foundation for sustainable development, which can only be achieved by adopting an appropriate management approach. Whether internationally or at a regional scale, successful management of marine ecosystems needs to be based on a scientifically robust approach to monitoring environmental change. Within such a framework, the conservation of marine biological diversity is problematic, as many conventional measures of diversity are not appropriate for measuring the types of change that require management. New indicators are required and in this paper we summarise some of the current methodology being used to derive such indices, which may be used to evaluate the effectiveness of marine stewardship initiatives. Through a series of examples we demonstrate the application of the taxonomic distinctness indicator of biodiversity to marine environmental assessment and its development towards becoming an operational tool.     

“人与自然和谐共生”愿景下生态产品价值实现机制与路径研究

生态产品价值实现是推动绿水青山转化为金山银山、促进人与自然和谐共生的关键路径和有效举措,对加快生态文明建设具有重要意义。本文根据生态产品的产权界限、公益性程度和供给消费方式,系统梳理了不同类型的生态产品价值实现模式,深入剖析了当下生态产品价值实现的制约瓶颈,如产权界定不清、法律制度不完善、市场机制不健全、生态补偿机制和保障体系有待进一步优化等。在此基础上,研究提出完善生态产品价值实现的针对性对策建议：(1)完善生态产品产权体系,夯实“绿水青山”向“金山银山”转化的制度基础;(2)培育生态产品市场建设,拓宽“绿水青山”向“金山银山”转化的市场化通道;(3)健全生态补偿机制,优化多主体利益联结机制;(4)强化生态产品价值实现保障体系,提升生态产品转化成效。     

脉冲放电脱硫产物的收集

实验结果表明利用给反应器加直流基压收集脱硫产物是可行的．产物收集效率随直流基压和停留时间的增加而增加,在本实验条件下,最高收集效率达到９５．１％ ．加直流基压后,脉冲电压、电流波形基本不变,放电增强,脱硫效果提高．加直流基压可使反应器在脱硫的同时有效收集产物．     

硫铁矿烧渣湿法制备铁系产品的原理和途径分析

本文叙述了硫铁矿烧渣的化学成分和物相 ,以及酸浸还原烧渣提取铁的基本原理。论述了硫铁矿烧渣湿法制备铁盐 ,铁氧化物颜料 ,铁基磁粉以及铁粉等铁系产品的原理 ,并对铁系产品的途径进行了分析。     

生态产品市场化实现路径及二元价格体系

本文从微观经济学角度阐释生态产品的市场化实现路径及其价格机制。认为生态产品市场化路径的前提是存在有形的,能够体现劳动价值,可交换的产品实体。鉴于现有研究所讨论的生态产品价值的体现皆源于各环境要素的支撑,因此可将清洁的水、空气、土壤等优质环境要素凝练为生态产品的基本有形载体。在此基础上,本文指出政府提供生态产品的有效路径有三条:创造、维系改善及修复。其中修复路径是现阶段市场化的优先选择方式。通过结合现阶段我国新的环保商业化模式——合同环境服务这一新命题,本文构建了生态产品合同环境服务政府采购的有效市场化路径,即政府通过绩效合同采购第三方环保服务,以综合环境目标为合同标的,通过所采购的一体化环境修复项目实现提供良好的生态产品。在此基础上围绕生态产品价格组成,本文提出生态产品的二元价格体系:指出生态产品买入与卖出的不同经济行为对应着生态环境的保护与开发两种对立的发展模式,这两种市场行为的外部性存在正负两种情景。综合考虑生产资料所有者属性,本文创新性地提出生态产品市场交易应采用买入-卖出二元价格体系。买入价格也称保护价格,主要考虑生产成本与利润,生产成本即生态修复项目的费用支出,其中利润是购买者(政府)予以产品生产者(提供修复服务的环保服务商)适当的利润空间,作为该生产者经济行为正外部性的补贴;出让价格也称牺牲价格,包括生产成本、社会成本(外部性成本)、生产资料成本、利润等,其中出让行为价格组成中的社会成本获益是政府,应主要用于支付环境管理成本。值得注意的是,在二元价格体系中,学者们讨论的生态产品价值与买入价格相关性不大,在数值或更接近出让价格。     

蔬菜出口产地农户对食品安全规制的认知及其农药决策行为研究

食品安全与农药残留一直是备受关注的焦点问题。基于此,本文应用山东省蔬菜出口产地安丘市392个农户的调查数据,对农户食品安全规制的认知及其农药使用行为的影响因素进行了分析。研究结果表明,农户的学历层次、农产品国内销售和出口日本的比例、农户对国内外农产品市场的评价及是否接受农药残留检测显著影响其对食品安全规制的认知;而农户的平均生产支出、是否接受农药残留检测、检测标准的严格程度及是否作生产记录影响其农药使用行为。此外,本文发现该制度的实施导致一些农户产生逆向选择,且农户的农药使用因种植结构而不同。针对当前农业生产的特点和食品安全现状,为了促进当地农业生产方式的转变和保护生态环境,政府应加强对农业主体的培训和技术指导,引导当地农户加强与产业组织的联系,有效开展农药残留检测、优化种植结构,提高农产品的质量和国际竞争力。