固相微萃取和气相色谱法联用分析饮用水中甲基叔丁基醚

甲基叔丁基醚(MTBE)是一种新型的无铅汽油添加剂,研究发现,MTBE是一种潜在的致癌物,在加油站、油库、地下储油槽和汽油炼制过程泄漏的MTBE造成地表水、地下水、饮用水和土壤等污染.     

垃圾污染质在粉质粘土包气带中运移情况的调查

在我国填埋仍是垃圾处理的主要方式.垃圾产生的渗滤液量大、组分复杂,重金属及有机物含量极高,对土壤及地下水环境污染严重[1].渗滤液污染地下环境的过程主要包括污染物质在包气带中的垂向运移和透过包气带后在含水层中的侧向运移.因此,包气带是阻止渗滤液污染含水层的天然屏障,可以通过对污染物质的阻截和自然衰减,起到削弱污染、保护含水层的作用.因此研究垃圾渗滤液污染物,特别是在不同岩性包气带介质中的迁移转化十分必要.     

地表水中典型磺胺类抗生素的自然衰减

近年来,磺胺类抗生素因大量使用,在河流等地表水中广泛检出,其环境行为及生态危害,成为备受关注的环境问题.本文以10种常见磺胺类抗生素为研究对象,通过微宇宙实验,模拟其在河流表层水中的自然衰减规律,同时模拟直接光降解、间接光降解、水解、细菌降解和微生物降解等多种条件,以阐明不同环境因素对磺胺类抗生素自然衰减的作用机制.结果显示,10种磺胺类抗生素在168 h内的自然衰减率可达55%—100%,半衰期为14.7—115.5 h,表明磺胺类抗生素在进入河流等地表水后可发生自然衰减.结构方程模型分析表明,直接光降解及间接光降解是磺胺类抗生素自然衰减的主要途径,而水解和微生物降解的作用不大.采用高分辨率质谱,共检出7种降解产物,推测磺胺类抗生素的转化路径主要包括N—S键断裂及羟基化作用.ECOSAR毒性分析结果表明,转化产物毒性多低于母体抗生素,但仍可能存在潜在的环境风险,需进一步深入研究.     

甲基叔丁基醚(MTBE)蒸腾流浓度因子(TSCF)的试验评估

甲基叔丁基醚(MTBE)是北美燃料市场最常用的汽油添加剂，由于在土壤中的不吸附性和极高的水溶性．MT-BE已成为一种蔓延性的地下水污染物．植物修复技术被认为是目前对MTBE污染治理最为有效的方法之一．蒸腾流浓度因子（TSCF)作为植物修复技术中十分重要的参数，其通常是用污染物的辛醇-水分配系数(Kow)直接评估的。由于不同植物其体内脂肪含量不同，所以如果仅用污染物的Kow值来计算其TSCF值，往往不能准确表达污染物在植物体内的传输行为．由于MTBE在植物体内不发生降解，植物挥发是MTBE植物修复技术中唯一的作用机理．本实验用一自行设计的植物反应器来测定MTBE在不同温度条件下的TSCF值．长出新根须和嫩叶的柳树(Salix alba)枝条在一容积500mL的植物反应器中生长9-12d(其中MTBE溶液500mL，浓度4．81-6．60mg／L)来观察柳树对MTBE的吸收。MTBE的去除率和柳树的蒸腾量之间的关系用来计算其TSCF值．在15℃，20℃和25℃条件下，MTBE的TSCF值分别为0.58,0.75和0.49．本实验结果表明，柳树对MTBE的吸收是一个被动的行为，并且MTBE在柳树体内随蒸腾流的传输也有一定的限度。图2表1参11。     

大同盆地富砷地下水的水化学与地球化学研究

为弄清大同盆地地下水中影响砷的迁移、富集的主要地球化学与生物地球化学过程,为区域供水安全提供指导作用,针对高砷地下水系统开展了水文地球化学与含水层沉积物全岩地球化学研究;并在此基础上探讨了研究区高砷地下水成因。结果表明,研究区高砷地下水为偏碱性、强还原环境,砷含量为0.31～452μg·L-1,主要以砷酸盐形式存在,地下水中砷与三价铁的浓度有显著的相关性。高砷含水层沉积物中有机质、铁与砷含量表现出显著相关性。以上结果说明,碱性还原环境有利于地下水中砷的富集;微生物参与下,沉积物相有机质的氧化和Fe氧化物/氢氧化物的还原过程是本区高砷地下水形成的主控因素。     

沉积物中汞的甲基化研究进展

汞是环境中存在的一种重要污染物质,其毒性与之化学形态密切相关。环境中的汞主要以无机汞形态存在,然而无机汞可以通过甲基化作用转化为毒性更强的甲基汞,从而给受到暴露的生物及人类带来更高的健康风险。沉积物是汞在水生环境系统中的主要分布相,也是无机汞甲基化过程发生的主要场所。沉积物中汞的甲基化过程受到生物种类、汞的生物可利用性等生物因素及温度、含硫化合物、有机质、氧化还原条件等环境理化性质的影响。本文对汞在沉积物中甲基化过程的作用机制及其影响因素的研究现状及最新进展进行了总结,并对未来更深入的研究进行了展望。     

生物扰动对沉积物中污染物环境行为与生物可利用性的影响

疏水性有机污染物进入环境水体后易于与沉积物结合,对沉积物中的底栖动物造成危害。底栖动物引起的生物扰动作用可以通过改变沉积物的地球化学性质,对其中污染物的赋存形态、迁移转化和生物可利用性产生重要影响。在综述了国内外生物扰动影响沉积物中污染物环境行为和生物可利用性的最新研究进展基础上,重点讨论了沉积物颗粒交换、水体环境条件改变、疏水有机污染物解吸释放过程以及对生物扰动影响的定量化表征。最后对该研究方向进行了展望,指出应重点研究多种污染物及不同生物共存条件下的生态效应,以及造成沉积物扰动的影响因素的定量化表征等。     

地下水中铵态氮的迁移转化过程

铵态氮进入地下水的主要途径是土壤淋失,通过室内土柱淋滤实验研究铵态氮在土壤中的迁移转化过程,测定不同时间和不同深度土壤中铵态氮及其转化物硝态氮和亚硝态氮的浓度变化,分析了影响铵态氮迁移转化的因素。实验表明：在土壤饱和、持续淋滤条件下,土柱中随采样深度的增加,铵态氮穿透时间延长,依次滞后;通过硝化能力分析,土柱上层发生了轻微的硝化反应,土柱底部发生了反硝化反应,导致硝态氮的浓度衰减。研究认为在铵态氮的迁移转化过程中,当入渗铵态氮浓度较低时,影响铵态氮迁移转化的显著因素是土壤对铵态氮的吸附;当入渗铵态氮浓度较大时,影响铵态氮迁移转化的显著因素是生物作用导致的铵态氮的硝化,以及土壤的渗透系数、弥散度等因素。     

河流有机质生物地球化学研究进展

探讨了近年来河流中有机质的生物地球化学研究状况。大多数河流有机质的来源主要是外源即流域侵蚀而来的,经过河流的新陈代谢过程,把河流中的悬浮物分解为不同类型的有机质。在有机质分解过程中由于外部条件的差异,形成粒径大小不同的颗粒物和溶解有机质、无机质等。河流水体中的溶解有机碳(DOC)在全球不同纬度、不同区域,其含量差异较大,但目前对其生物地球化学控制的量级缺乏足够的理解和认识。另外碳氮同位素及其比值在当前的河流有机质生物地球化学研究中仍起着非常重要的示踪作用。     

生物电化学脱氮技术研究进展北大核心CSCD

生物电化学系统（BES）因兼有污染物去除与能量回收等优点,近年来已成为环境污染治理领域的关注热点. 对生物电化学技术在脱氮方面的基本原理、含氮污染物的转化途径进行综述,主要的生物脱氮过程包括阴极反硝化、阳极氨氧化以及阴极同步硝化反硝化等,而非生物脱氮过程包括NH3/NH4^＋的跨膜转移、氨气逃逸等. 总结已报道的BES中主要脱氮微生物及其脱氮机制,BES中多数反硝化菌属于变形菌门（Proteobacteria）;硝化细菌主要是亚硝化菌属（Nitrosomonas）和硝化杆菌属（Nitrobacter）;在同步硝化反硝化过程中,电极上的硝化、反硝化菌有明显的分层现象. 最后阐述了生物电化学脱氮技术在生活污水、渗滤液、地下水处理等领域的最新应用研究,通过改变反应器构型以及运行模式等条件构建不同BES处理各类污水,以达到去除污染物同时回收电能或资源的目的. 基于目前BES的优势,认为减少脱氮中间产物（NO2^- -N、N2O）的积累及扩大BES规模对电能输出和污染物去除效果的影响将是未来的研究方向. （图3 表2 参66）     

Natural attenuation of MTBE and BTEX compounds in a petroleum contaminated shallow coastal aquifer

Natural attenuation of MTBE and BTEX compounds in a petroleum contaminated coastal aquifer in the Tel-Aviv area was investigated. Significant decrease in MTBE concentration and complete disappearance of BTEX compounds occur within 100 m groundwater flow. Highly anaerobic conditions were determined in the close vicinity to the spill source. In order to examine the contribution of microbial degradation to the attenuation process at anaerobic conditions, compound-specific carbon isotope ratio analysis was employed. Carbon isotope enrichment of toluene up to 2.4% along with the drop in its concentration up to 80% was observed within 20 cm below the water table. The lack of isotope fractionation despite the significant concentration decrease for other studied compounds indicates significant contribution of abiotic processes to the natural attenuation.     

Degradation of bisphenol A by photo-fenton processes

The photo-Fenton reactions, which could yield hydroxyl radicals via the catalytic degradation of H₂O₂ by Fe(II), were focused as one of the abiotic degradation processes of bisphenol A (BPA) in surface waters. At pH 6, in the presence of H₂O₂ only, 32% of BPA was degraded after 120?min of irradiation. However, 97% of BPA was degraded in the presence of both H₂O₂ and Fe(II). Without light irradiation, no BPA degradation was observed even in the presence of Fe(II) and H₂O₂. These results show that photo-Fenton processes are effective in the natural attenuation of BPA in surface water. In addition, the presence of humic acids (HAs), which were of more aliphatic nature, resulted in enhancing BPA degradation via the photo-Fenton processes. Therefore, HAs can be one of the important factors in enhancing the degradation of BPA in surface water via the photo-Fenton processes.     

稳定同位素在污染物溯源与示踪中的应用

由于稳定同位素在特定污染源中组成确定,且具有分析结果精确可靠、在污染物迁移与转化过程中不发生显著变化的特点,故已被广泛应用于环境污染事件的仲裁、环境污染物的来源分析与示踪研究中。介绍了稳定同位素分馏对于来源分析的影响以及稳定同位素技术在污染物溯源与示踪中识别大气多环芳烃来源、推测环境中硫和铅的来源、考察甲基叔丁基醚来源与降解过程等方面的应用进展。     

Meta-ecosystem engineering: nutrient fluxes reveal intraspecific and interspecific feedbacks in fragmented mussel beds

Ecologists still have to elucidate the complex feedback interactions operating among biodiversity and ecosystem processes in engineered systems. To address this, a field experiment was conducted to mimic natural mussel bed meta-ecosystems (Mytilus spp.) of the lower St. Lawrence Estuary (Quebec, Canada) and partition the effects of their biotic and abiotic properties and spatial structure on ecosystem processes and community dynamics of associated macro-invertebrates. We found positive intraspecific feedbacks between mussels and their recruits, and negative interspecific feedbacks between mussels and their associated ecosystem. These feedbacks were associated with mussel bed ecosystem processes (fluxes of ammonium and oxygen). In addition, we showed that proximity between mussel patches increased within-patch nutrient fluxes. Our study revealed the potential for meta-ecosystem engineering to drive feedback interactions between community and ecosystem functioning in marine fragmented systems. It also shows the relevance of meta-ecosystem theories as a conceptual framework to elucidate biotic and abiotic processes controlling ecosystem and community structure. Such framework could contribute to ecosystem-based management of spatially structured systems such as reserve networks and fragmented ecosystems.     

红壤胶体铁氧化物界面有机氯的非生物转化研究进展

综述了红壤胶体铁氧化物的结构、形态及其转化;铁氧化物界面有机氯的非生物转化过程及其影响因素;异化铁还原作用下的有机氯转化过程。有机氯的非生物转化主要包括氧化转化与脱氯转化过程。氧化转化包括暗态下的化学氧化与光化学氧化过程;脱氯转化包括脱氢卤化、加氢脱氯、脱双卤、二聚脱氯与亲核置换脱氯等反应过程。有机氯的非生物转化主要受胶体界面pH、Eh、水溶性有机物、金属离子、铁氧化物形态与铁还原细菌等的显著影响。有机氯非生物转化的化学-微生物耦合机制、复合污染条件下重金属对界面有机氯非生物转化过程的影响机制、红壤胶体界面有机氯污染的综合调控技术方法等三个方面值得关注,有助于推动土壤胶体界面环境化学的发展。     

A review of selection‐based tests of abiotic surrogates for species representation

Because conservation planners typically lack data on where species occur, environmental surrogates—including geophysical settings and climate types—have been used to prioritize sites within a planning area. We reviewed 622 evaluations of the effectiveness of abiotic surrogates in representing species in 19 study areas. Sites selected using abiotic surrogates represented more species than an equal number of randomly selected sites in 43% of tests (55% for plants) and on average improved on random selection of sites by about 8% (21% for plants). Environmental diversity (ED) (42% median improvement on random selection) and biotically informed clusters showed promising results and merit additional testing. We suggest 4 ways to improve performance of abiotic surrogates. First, analysts should consider a broad spectrum of candidate variables to define surrogates, including rarely used variables related to geographic separation, distance from coast, hydrology, and within‐site abiotic diversity. Second, abiotic surrogates should be defined at fine thematic resolution. Third, sites (the landscape units prioritized within a planning area) should be small enough to ensure that surrogates reflect species’ environments and to produce prioritizations that match the spatial resolution of conservation decisions. Fourth, if species inventories are available for some planning units, planners should define surrogates based on the abiotic variables that most influence species turnover in the planning area. Although species inventories increase the cost of using abiotic surrogates, a modest number of inventories could provide the data needed to select variables and evaluate surrogates. Additional tests of nonclimate abiotic surrogates are needed to evaluate the utility of conserving nature's stage as a strategy for conservation planning in the face of climate change.     

The emergence of stable isotopes in environmental and forensic geochemistry studies: a review

In the past decade, environmental forensics has emerged as a discipline directed toward determining parties liable for causing spills of contaminants into the environment. Such investigations, while geared toward determining the guilty parties in order to recover costs of the cleanup and remediation, require various questions to be addressed. These include determination of the nature of the product; Where did it come from?; Extent of weathering, if any; How long has it been there?; and Is it degrading naturally? Traditionally, these studies have been addressed through utilization of techniques such as gas chromatography (GC) and gas chromatography–mass spectrometry (GCMS). However, in recent years, stable isotopes, primarily determined through the use of combined gas chromatography–isotope ratio mass spectrometry (GCIRMS), have emerged as an equally important tool in environmental forensics. For relatively low molecular, volatile compounds such as MTBE, BTEX, or chlorinated solvents, the isotopes, primarily carbon and hydrogen, have been used extensively for evaluating the onset of natural attenuation. For larger molecules such as PCBs or PAHs, in which the effects of biodegradation on the isotope composition of these molecules is minimal, the isotopic fingerprints of the individual compounds can be used for correlation purposes. In this paper, a brief introduction to isotope geochemistry will be given, followed by a review of applications of stable isotopes to a variety of environmental problems. While the review may not necessarily be exhaustive, it will provide a comprehensive overview of areas where isotopes have been used and potential applications for the future. Most of the review is concerned with carbon and hydrogen isotopes, although a brief overview of the emerging area of chlorine isotopes will also be discussed.     

Climate change and its consequences for water and wastewater management

Life, in combination with solar radiation and abiotic processes, is most probably the reason why liquid water has existed on Earth for over billions of years, and the global mean temperature has remained in a lifeenabling range. Efforts to limit or even reverse global warming must be derived from the knowledge of the Earth’s complex life-support system. In this context, the balance between liquid and gaseous water plays a crucial role, and water management becomes an important field of innovation and action, globally, on the scale of watersheds but also on the very local level. Cascading use, reuse, and temporary storage of water in urban settings must be considered to limit over-extraction of water from natural resources, and to maintain the life supporting function of ecosystems. At the same time, public health requirements, cost efficiency, and reliability demands are to be met.