Effects of environmental factors on N2O emission from and CH4 uptake by the typical grasslands in the Inner Mongolia

The fluxes of N2O emission from and CH4 uptake by the typical semi-arid grasslands in the Inner Mongolia, China were measured in 1998-1999. Three steppes, i.e. the ungrazed Leymus chinensis (LC), the moderately grazed Leymus chinensis (LC) and the ungrazed Stipa grandis (SG), were investigated, at a measurement frequency of once per week in the growing seasons and once per month in the non-growing seasons of the LC steppes. In addition, four diurnal-cycles of the growing seasons of the LC steppes, each in an individual stage of grass growth, were measured. The investigated steppes play a role of source for the atmospheric N2O and sink for the atmospheric CH4, with a N2O emission flux of 0.06-0.21 kg N ha(-1) yr(-1) and a CH4 uptake flux of 1.8-2.3 kg C ha(-1) yr(-1). Soil moisture primarily and positively regulates the spatial and seasonal variability of N2O emission. The usual difference in soil moisture among various semi-arid steppes does not lead to significantly different CH4 uptake intensities. Soil moisture, however, negatively regulates the seasonal variability in CH4 uptake. Soil temperature of the most top layer might be the primary driving factor for CH4 uptake when soil moisture is relatively low. The annual net emission of N2O and CH4 from the ungrazed LC steppe, the moderately grazed LC steppe and the ungrazed SG steppe is at a CO2 equivalent rate of 7.7, 0.8 and -7.5 kg CO2-C ha(-1) yr(-1), respectively, which is at an ignorable level. This implies that the role of the semi-arid grasslands in the atmospheric greenhouse effect in terms of net emission of greenhouse gases (CO2, CH4 and N2O) may exclusively depend upon the net exchange of net ecosystem CO2 exchange.     

微波法磷改性斜发沸石的结构及水中除砷的研究

采用固固相、固液相同晶取代对斜发沸石进行微波法磷改性，并对改性前后的矿样采用化学分析，XRD，^31P MAS NMR等手段表征。结果表明，虽然微波磷改性不能改变沸石单斜晶系的主体骨架结构，但由于脱Al，脱Si和P同晶取代，使晶胞体积收缩，结晶度下降，比表面积、孔体积明显减小，骨架中Si和Al的键合方式发生变化，有四配位硅的Si—O—P结构出现，该结构是沸石阴离子交换的结构基础。沸石去除水中砷的结果表明，改性前，沸石去除水中砷的能力很小，属表面物理吸附，改性后，沸石去除水中砷的能力明显增强，属阴离子交换。而且水介质的酸度和同晶取代方法对沸石除砷都有明显影响。     

海洋微藻释放的他感物质及其研究进展

他感物质是浮游植物产生他感作用时向环境释放的化学物质,是浮游植物产生他感作用的媒介,尽管浮游植物他感作用的研究日益广泛,但以往的研究大都集中在他感现象的描述上,而对于他感物质的结构以及性质等的认识仍然存在很多未知。本文结合最新的研究成果,对他感现象和他感物质进行了综述,就目前微藻中主要发现的他感物质如酯类、酚酸类和萜类等,探讨了他感物质的特点、作用机理和影响因素,并重点介绍了他感物质的提取分离与鉴定等方面的研究进展,同时分析了当前海洋微藻中他感物质研究的不足,提出了新的研究思路,今后的研究重点是建立系统的分离鉴定海洋微藻释放的他感物质的方法,最终实现现场海域他感物质的分析。     

Spatio-temporal variability in fatty acid trophic biomarkers in stomach contents and muscle of Iberian sardine (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) and its relationship with spawning

Temporal variation in the fatty acid (FA) composition of stomach contents of Iberian sardines was compared to the relative contribution to dietary carbon made by different prey types for fish from two areas off Portugal. The effect of the FA content of the diet on sardine muscle FA composition was also studied, aiming at (1) analysing if FA biomarkers can be used as a complementary technique for the study of sardine diet and (2) to relate spatial and temporal variations of prey FA content with sardine condition and reproduction. Significant spatial differences in the FA composition of sardine diet occurred with concentrations of n-3 polyunsaturated FA, namely eicosapentaenoic acid [EPA, 20:5n-3] and linolenic acid 18:3n-3, being significantly higher in the diet of sardines from the west coast, whilst the diet of sardines from the south coast was richer in monounsaturated fatty acids (MUFA), namely the carnivory biomarker oleic acid 18:1n-9. These results are in agreement with the higher contribution made by diatoms and dinoflagellates to the diet of sardines off the west coast. Spatial variation in sardine dietary FA was also detected in their muscle composition, specifically for EPA, and the eicosapentaenoic/docosahexaenoic acid and (n-3)/(n-6) ratios, which were higher in sardines from the west coast. No difference in FA composition was detected between sexes, and the seasonal variability in sardine total FA concentration was primarily related to the seasonality of spawning. Sardines accumulate high concentrations of FAs during the resting stage of reproduction when the feeding intensity is similar or lower to that observed during the spawning season. Additionally, sardines show a high selective retention of MUFA and polyunsaturated FA (PUFA) throughout the year except at the beginning of the spawning season, when these FAs are largely invested in the formation of the gonads. Therefore, temporal and regional differences of prey environments are strong enough to be reflected in fish body composition, namely on the accumulation of essential FAs, which can have a strong impact on reproduction success for this species.     

余小萱负重践行"绿色奥运"

记者在约定的时间来到奥组委环境部所在的青蓝大厦,余小萱部长已在办公室走廊里笑迎。这位1974年即投身环保工作,曾任北京市环保局副局长10余年的奥组委官员,虽然讲话慢条斯理,可身负的责任和压力却绝不轻松——随着明年初都灵冬奥会的结束,世界投向北京的目光将越来越多、越来越挑剔,北京自申奥伊始即提出的“绿色奥运”能否兑现,自然倍受关注。[编者按]     

Spatial heterogeneity of greenhouse gas emissions from cereal crop production in China

Environmental Chemistry Letters - China is a major producer of wheat, maize and rice, which generates massive greenhouse gas emissions due to the consumption of elevated amounts of energy, land,...     

旋流诱导介质振荡再生增强含油污水微通道分离

受微通道分离介质再生后截滤残留污染物影响,常规微通道分离效率持续衰减,成为抑制微通道分离广泛高效应用的关键瓶颈。通过开发旋流振荡再生单元,研究了旋流振荡再生强度和振荡再生结构对微通道分离装置过滤介质再生效率的影响,由此集成研发沸腾床分离器,考察了装置对实际含油污水的分离效率,并分析了微通道振荡再生对沸腾床分离的强化原理以及装置的分离经济性。结果表明,当再生强度为5.0 L·(s·m²)⁻¹时、再生15 min后采用轴向振荡再生结构,沸腾床分离器达到最佳再生工况。在最佳再生工况下开展10 m³·h⁻¹实际含油污水连续处理实验,针对油质量浓度为30~200 mg·L⁻¹、悬浮物质量浓度为25~200 mg·L⁻¹的来水,装置出水平均油分和悬浮物质量浓度分别降至11.4 mg·L⁻¹和23.5 mg·L⁻¹,并可在来水最高油质量浓度和悬浮物质量浓度接近50 000 mg·L⁻¹的冲击工况下,确保出水平均油分和悬浮物质量浓度降至15.9 mg·L⁻¹和29.8 mg·L⁻¹。利用沸腾床分离器再生结构中旋流诱导的过滤介质表界面污染物振荡运动,分离过程中截滤残留的油分和悬浮物等污染物被及时脱附,实现颗粒介质表界面彻底更新,确保装置长周期稳定运行。以200 m³·h⁻¹规模实际含油污水处理为例,沸腾床分离工艺相对涡凹气浮和溶气气浮的组合工艺,可完全取消化学絮凝药剂消耗且不产生化学浮渣,且具有显著的经济环保效益。     

拦河闸工程设计和施工中的风险分析和管理

水利工程的风险分析和风险管理正日益受到工程界的重视。渭河宝鸡市区段拦河闸工程的规划、设计和施工过程中的各项关键决策，都应用了风险分析与管理的方法，包括闸址及蓄水区地质条件的风险分析与管理、泄洪能力及运行风险分析与管理、工程施工过程风险分析与管理、拦河闸工程环境影响风险分析与管理以及拦河闸工程投资风险分析与管理。工程的按时完工、运行的可靠性和安全性，在很大程度上都得益于项目的风险分析与管理工作的贯彻和实施。实践证明，在水利工程决策过程中引进风险分析和风险管理是必要和有益的。     

Ethylene,xylene, toluene and hexane are major contributors of atmospheric ozone in Hangzhou,China, prior to the 2022 Asian Games

Environmental Chemistry Letters - The occurrence of volatile organic compounds (VOCs) in the atmosphere is a major health issue, notably in China, because those compounds are the precursors of...     

曝气生物滤池中滤料的应用研究进展

介绍了曝气生物滤池的工作原理和生物滤料的性能;重点综述了无机滤料的分类、滤料的改性和复合陶粒生物滤料的应用情况,并对双层滤料工艺进行了讨论;指出今后应加强生物膜在滤料上的生存特征及适应性的研究,以便寻求能改善滤料性能的新工艺和方法。