Effects of nonionic surfactant Triton X-100 on the laccase-catalyzed conversion of bisphenol A

The laccase-catalyzed conversion of bisphenol A (BPA) in aqueous solutions was studied in the absence and presence of nonionic surfactant Triton X-100. It was found that the addition of Triton X-100 into the reaction system increased the conversion of BPA, especially near the critical micelle concentration of Triton X-100. Also it was found that the stability of laccase was greatly improved in the presence of TritonX-100. Studies on the endogenous fluorescence emission of laccase indicated that there existed an interaction between Triton X-100 and laccase, which was beneficial to folding and stabilizating of laccase. The binding of Triton X-100 to the laccase surface also mitigated the inactivation e ect caused by the free radicals and polymerization products. Under otherwise identical conditions, a lower dosage of laccase was needed for the higher conversion of BPA in the presence of Triton X-100.     

安徽沿江地区的矿产资源开发与产业结构调整

安徽沿江地区依托矿产资源和长江水运的双重优势，矿业经济发展现已初具规模，城市专业化分工明显，但经济总体水平较低，产业结构层次不高。通过对沿江地区矿产资源开发态势、产业结构的现状分析，得出了本区调整产业结构的必然性，并提出了调整产业结构的主要措施和途径。     

基于DEA方法的农地非农化效率研究

论文运用DEA方法构建了一个农地非农化效率指标,并利用2001-2008 年间省级层面数据,测算得到各省以及4 个地区历年农地非农化效率,结果表明：省域农地非农化效率呈现波动上升、波动下降、保持平稳三种趋势,4 个区域唯有东北老工业基地的农地非农化效率均值高于0.6,全国农地非农化效率均值为0.489,表明8 a 中我国多耗用了51.1%（将近91455.75 hm²）的建设占用耕地的指标。同时,由于初始年份的低效区与高效区在效率变动趋势上存在此消彼长的关系,省域及4 个地区之间农地非农化效率出现趋同的现象。对农地非农化效率影响因素的分析蕴含着“权利二元”的土地制度是过度农地非农化与农地非农化配置结构不合理的症结所在;同时,地方政府财政支出压力又进一步助长了农地非农化的“非理性”;此外,在影响农地非农化效率其他因素中,第三产业比重达到47.02%水平以后,产业结构升级的边际效应才由负变为正;而经济发展水平和城市化率在不同地区的作用方向和强度不同,致使其在全国层面上统计不显著。据此,论文提出应实施“双轮驱动型”土地制度和财税制度改革,以扭转农地非农化效率损失的局面。     

长江流域旱涝灾害特征研究

利用长江流域地区(1956-2007年)148个站点全年的逐日降水资料,采用Z指数作为旱涝指标,对长江流域地区旱涝的转化规律及其时空变化特征进行了探讨,结果表明:长江流域降水量具有明显的年际变化,夏季和年降水量的变化趋势一致;春季的降水周期较夏季具有明显的周期性,从研究的时段内看,春季降水周期为17 ～21年为主,夏季以10～ 15年为主周期;旱涝灾害发生的频率与降水量、暴雨出现的频数呈现正相关,旱涝空间分布上存在一定的结构性,干旱大都发生在长江上游地区(四川和云南的一部分地区)以及湖北部分地区,洪涝主要发生于长江中下游地区,特别是在湖南、安徽、湖北等地.     

穗花狐尾藻对外源15N在水-沉积物界面迁移转化的影响

通过构建室内模拟系统,利用同位素示踪技术研究过量外源NO3-在微环境中的归趋及生长期的穗花狐尾藻(Myriophyllum spicatum L.)在外源氮迁移转化中的作用.结果表明:在穗花狐尾藻组,反硝化作用、微生物固定、沉水植物吸收、异化硝酸盐还原成氨(DNRA)和转化为可溶性有机氮(DON)的去除作用分别占添加15N的47.54%、25.24%、12.76%、0.52%、1.21%;在对照组,反硝化作用、微生物固定、DNRA作用和转化为DON的去除作用分别占添加15N的32.74%、30.79%、0.54%、5.83%.在穗花狐尾藻组和对照组中约87.24%和69.90%的NO3-进行了转化.反硝化作用是去除两处理组中NO3-的主要方式,其次是微生物的固定作用,穗花狐尾藻的直接吸收也对NO3-的去除起到重要作用,DNRA作用和DON对NO3-的去除作用较小.穗花狐尾藻促进了反硝化作用,加快了NO3-在微环境中的迁移转化,直接或间接地促进了微环境对外源NO3-的去除.     

2019年国庆节前后北京气态氨和气溶胶铵盐浓度的同步观测

我国自2013年实施《大气污染防治行动计划》以来,大气细颗粒物（PM_2.5）特别是硫酸盐浓度迅速下降,但硝酸盐浓度降幅较小,大气中过量的氨气（NH₃）是维持硝酸盐居高不下的主要因素.迄今,我国生态环境部门尚未将NH₃纳入常规观测,以往有关NH₃和气溶胶铵盐（NH₄⁺）的研究多是分别进行的,缺少同步观测.由于NH₃和NH₄⁺在大气中可互相转化,只测量其中一种相态很难全面了解它们的动态变化.本研究基于酸涂覆的蜂窝型扩散管和膜采样串联系统,同步测量了2019年国庆节前后北京城区大气NH₃和NH₄⁺浓度,时间分辨率为2 h（PM_2.5>35 μg·m^-3）~5 h（PM_2.5<35 μg·m^-3）.结果表明,采样期间NH₃和NH₄⁺平均浓度分别为（4.1±2.9）μg·m^-3和（1.7±1.4）μg·m^-3,且二者均与PM_2.5、CO和NO₂呈现相似的时间变化规律.NH₃浓度在早晨（05：30~08：30）和夜间（21：30~05：30）较高,这种双峰日变化特征在污染天（PM_2.5>75 μg·m^-3）最为明显.NH₃浓度在污染天17：30~21：30存在明显的低谷,这主要与有利的扩散条件有关（平均风速6 m·s^-1）.NH₄⁺浓度的日变化特征与NH₃差异较大,NH₄⁺浓度在非污染天（PM_2.5<75 μg·m^-3）17：30~21：30出现明显峰值,期间NH₃浓度较低,而NO₂浓度较高.在非污染天,NH₃浓度是NH₄⁺的2.8倍;而在污染天,由于气粒转化加速,大气NH₃浓度低于NH₄⁺（NH₃/NH₄⁺=0.8）.国庆节前大气NH₃、CO、NO₂、SO₂和PM_2.5浓度超过国庆后的幅度分别为54.2%、40.4%、33.3%、0.0%和49.4%.国庆节前虽然实施了减排行动,但极端不利的静稳天气导致大气环境容量下降,掩盖了污染物减排的效果,导致大部分污染物浓度不降反升.     

δ15N-stable isotope analysis of NHx: An overview on analytical measurements,source sampling and its source apportionment

• Challenges in sampling of NH₃ sources for d¹⁵N analysis are highlighted. • Uncertainties in the isotope-based source apportionment of NH₃ and NH₄⁺ are outlined. • Characterizing dynamic isotopic fractionation may reduce uncertainties of NH_x science. Agricultural sources and non-agricultural emissions contribute to gaseous ammonia (NH₃) that plays a vital role in severe haze formation. Qualitative and quantitative contributions of these sources to ambient PM_2.5 (particulate matter with an aerodynamic equivalent diameter below 2.5 µm) concentrations remains uncertain. Stable nitrogen isotopic composition (δ¹⁵N) of NH₃ and NH₄⁺ (δ¹⁵N(NH₃) and δ¹⁵N(NH₄⁺), respectively) can yield valuable information about its sources and associated processes. This review provides an overview of the recent progress in analytical techniques for δ¹⁵N(NH₃) and δ¹⁵N(NH₄⁺) measurement, sampling of atmospheric NH₃ and NH₄⁺ in the ambient air and their sources signature (e.g., agricultural vs. fossil fuel), and isotope-based source apportionment of NH₃ in urban atmosphere. This study highlights that collecting sample that are fully representative of emission sources remains a challenge in fingerprinting δ¹⁵N(NH₃) values of NH₃ emission sources. Furthermore, isotopic fractionation during NH₃ gas-to-particle conversion under varying ambient field conditions (e.g., relative humidity, particle pH, temperature) remains unclear, which indicates more field and laboratory studies to validate theoretically predicted isotopic fractionation are required. Thus, this study concludes that lack of refined δ¹⁵N(NH₃) fingerprints and full understanding of isotopic fractionation during aerosol formation in a laboratory and field conditions is a limitation for isotope-based source apportionment of NH₃. More experimental work (in chamber studies) and theoretical estimations in combinations of field verification are necessary in characterizing isotopic fractionation under various environmental and atmospheric neutralization conditions, which would help to better interpret isotopic data and our understanding on NH_x (NH₃ + NH₄⁺) dynamics in the atmosphere.     

基于土地利用变化模型的退耕还林还草决策分析——以通辽地区为例

通过综合考虑影响退耕还林还草的自然和社会因素,结合土地利用规划和遥感影像解译结果,论文以通辽地区为例,介绍了利用土地利用变化模型确定退耕还林还草区域的方法和过程。根据对2010年模型模拟结果和2000年通辽地区土地利用现状的对比分析,结果发现2000～2010年该地区进行退耕还林还草的合适区域应该主要位于研究地区的中部、南部,以及北中部。研究地区中部属于科尔沁沙地的腹地,土地沙漠化最为严重,同时城镇和农村居民点分布较密,退耕还林还草是政府用于减缓风沙对城镇和农村居民点危害程度的重要生态措施;而南部和北中部属于丘陵和山区,由于过度开垦,水土流失较为严重,是实施退耕还林还草的重点区域。此外,与退耕还林区相比,退耕还草区距城镇、农村居民点以及道路相对较远,具有可达性较差、地理位置较为偏僻的特点。论文得出的结果可为今后通辽地区退耕还林还草工程的实施提供科学依据,同时,该文提出的确定退耕还林还草区域的方法对其它地区具有一定的借鉴意义。     

东南沿海地区土地利用转换态势与机制分析

引进土地利用动态度、利用优势度和类型复杂度评判指标,重点揭示20世纪90年代东南沿海地区土地利用类型转换程度、时空差异及其机制。研究表明:东南沿海地区耕地减少122.2×10⁴hm²,建设用地增加85.9×10⁴hm²。土地利用类型转换态势受区域经济社会发展水平及其结构变动的深刻影响。市场经济体制的完善和个体股份机制的创新为沿海土地利用类型快速转换提供了政策平台。人口增长与技术进步是土地利用类型转换的原动力,并通过推进各类产业园区(包括开发区)、中心村镇建设而作用于土地利用类型转换的全过程。     

Health and Welfare in Danish Dairy Cattle in the Transition to Organic Production: Problems, Priorities and Perspectives

During the past few years,organic dairy farming has grown dramatically inDenmark. Consequently, an increasing number ofpeople are encountering this method ofproduction for the first time. Amongst these,many veterinarians have suddenly had to dealwith organic herds in their home district, and,meeting examples of poor animal welfare, theyhave recently started to express some concerns.Against this background, a so-called``Synthesis of Knowledge' project was initiatedto examine the health and welfare of dairycattle and the use of medication in thetransition to organic production. The aim ofthe project was to investigate associatedproblems from the point of view of the dairyherd. Based on qualitative research interviewswith vets and agricultural advisors, as well asfocus group interviews with farmers who hadrecently converted from conventional to organicfarming, an expert panel attempted to identifyproblem areas and possible solutions. Theproblems related to (a) the adjustment to newand unknown practices, (b) poor management ingeneral, and (c) inappropriate legislation fororganic farming.One problem area was the rearing of dairycalves, particularly with regard to theestablishment of post partumrelationships between cow and calf, grouphousing, and the grazing of young animals. A``natural life' was identified as beingfundamental to organic animal husbandry. Interms of animal welfare, this concept can beunderstood as a way of living in which the calfis allowed to express its natural behavior andsatisfy its natural needs. Essentially, theconditions needed for good calf welfare requirethe compatibility and interplay of elementsfrom ``nature' (the natural life; includingopportunities to satisfy natural needs) and``culture' (farmer management skills; exerciseof care). These elements should be balanced toensure animal welfare in organic herds.