The long range transport of ozone within Europe and its control

It is widely accepted that the ozone concentrations experienced during photochemical episodes over large areas of Europe may exceed levels at which adverse environmental effects could be expected. These peak ozone concentrations can be reduced by controlling atmospheric emissions of the hydrocarbon and nitrogen oxide precursors. For ozone control to be successful over the spatial scale of Europe, long term international cooperation is required in the formulation of emission abatement strategies. A significant barrier to rapid progress has been the complexity of the processes that describe ozone formation. Highly sophisticated computer models of chemistry and transport have, up to now, been the only means to study the impact of abatement strategies. An alternative approach has been adopted here involving the development of a simplified long range transport model for ozone based on the analysis of over 60 experimental runs of a photochemical trajectory model applied to a wide range of hydrocarbon-nitrogen oxide emission combinations. Using the ozone-precursor relationship obtained, it has been possible to examine various policy options in the European context. Although taken together, three illustrative emission control scenarios reduce NO(x) and hydrocarbon emissions substantially through controls on motor vehicle exhaust, large combustion plant and solvent usage, a significant potential for photochemical ozone formation and long range transport may still remain after their implementation. The extents of precursor emission abatement that will be required, if the potential for ozone formation is to be reduced below published air quality criteria guidelines or critical levels, have been determined for each European country. The implied reductions in NO(x) and hydrocarbons relative to current levels amount to between 50 and 90%.     

The mechanism of enhanced biological phosphorus removal washout and temperature relationships.

In this study, the combined effects of temperature and solids retention time (SRT) on enhanced biological phosphorus removal (EBPR) performance and the mechanism of EBPR washout were investigated. Two pilot-scale University of Cape Town (South Africa) systems fed with synthetic wastewater were operated at 5 and 10 degrees C. The results showed that the phosphorus removal performance was optimum at total SRT ranges of 16 to 24 days and 12 to 17 days for 5 and 10 degrees C, respectively, and steady-state phosphorus removal was greater at the lower temperature. Higher SRT values of up to 32 days at 5 degrees C and 25 days at 10 degrees C slightly reduced EBPR performance as a result of increased extent of endogenous respiration, which consumed internally stored glycogen, leaving less reducing power for poly-hydroxy alkanoate (PHA) formation in anaerobic stages. The phosphorus-accumulating organism (PAO) washout SRTs of the systems were determined as 3.5 days at 5 degrees C and 1.8 days at 10 degrees C, considerably less than the washout SRTs of nitrifiers. Polyphosphorus, the main energy reserve of the EBPR bacterial consortium, was not completely depleted, even at washout points. The inability of EBPR biomass to use glycogen to generate reducing power for PHA formation was the major reason for washout. The results not only suggest that glycogen mechanism is the most rate-limiting step in EBPR systems, but also that it is an integral part of EBPR biochemistry, as proposed originally by Mino et al. (1987), and later others (Pereira et al., 1996, Erdal et al., 2002; Erdal, Z. K., 2002). The aerobic washout SRT values (2.1 and 1.2 days for 5 and 10 degrees C, respectively) of this study did not fit the linear line for PAO washout developed by Mamais and Jenkins (1992). Perhaps this was because the feeds used during this study were chemical-oxygen-demand-limited (acetate-based synthetic feed), whereas the feeds used for their study were phosphorus-limited (external acetate added to domestic wastewater), resulting in different ratios of PAOs and nonPAOs in the biomass.     

The aging process of naturally emitted aerosol (sea-salt and mineral aerosol) during long range transport

The aging processes of two representative natural aerosol, sea-salt and mineral aerosol, are investigated by using a box model equipped with a thermodynamic module (SCAPE). The model is shown to successfully describe the aging processes between the gas-phase anthropogenic pollutants (SO₂, NO_x, and NH₃) and primary aerosol particles, including self-neutralization process/chlorine depletion in the sea-salt aerosol; formation/dissipation of carbonate and bicarbonate ions in the mineral aerosol; irreversible dynamic deposition of SO₂ and H₂SO₄; and reversible thermodynamic distribution of inorganic volatile species. It is found that SO₂ and H₂SO₄ tend to deposit onto the mode with the largest surface area, and that ammonia deposition is controlled by preceding SO₂/H₂SO₄ deposition. During the SO₂/H₂SO₄ deposition, chloride and carbonate are continuously released from the sea-salt and mineral dust particles, respectively. The findings by the model predictions are consistent with field and observational studies.     

硫铝酸盐水泥及其改性材料对典型重金属的去除性能

应用经济高效的材料和简易的方法去除水中重金属已成为当前的研究热点。选择硫铝酸盐水泥(L)及其改性材料(LA)为清除剂,以Cu²⁺、Pb²⁺、Zn²⁺、Cd²⁺ 4种典型的重金属离子为研究对象,通过考察L和LA去除重金属过程中单因素的影响,对去除条件进行了优化,此外,通过竞争吸附实验及吸附动力学模型探究了对金属离子的去除机理。结果表明,L和LA可以有效地去除废水中的重金属离子,在pH为3.0~10.0条件下能够以较少的投加量(0.05~3 g·L⁻¹)使目标离子达到94%以上的去除率,30 min内表观吸附速率可降到零。相比之下,LA对金属离子的去除率略高于L。在最佳应用条件下,金属离子的去除率基本在90%以上。在竞争吸附实验中Cu²⁺的竞争性最强,且其能够促进其他离子被吸附。吸附动力学分析表明,L和LA对重金属的吸附是以化学吸附为主,去除机理以水解沉淀为主。以上研究结果可为该类材料对重金属的处理提供参考。     

聚合氯化铝/聚丙烯酰胺复合改性凹凸棒土絮凝材料的制备及其除浊除藻效果

蓝藻水华已成为我国湖库面临的主要环境问题,而利用黏土治理有害藻华技术在我国应用已有十多年的历史,是国际上公认的最具发展前景的措施之一。通过选用凹凸棒土(AT)为原材料,聚合氯化铝(PAC)、聚丙烯酰胺(PAM)作为改性剂,制备新型复合絮凝材料凹凸棒土-聚合氯化铝-聚丙烯酰胺(AT-PAC-PAM)。比较不同原料配比条件下复合絮凝材料的除浊效果,并对絮凝材料改性前后微观形貌、物化性质进行表征分析,然后通过单因素实验对复合絮凝材料除浊除藻条件进行优化,最后采用电子显微镜观察不同絮凝材料处理藻液所生成的絮体形貌差异。研究结果表明：AT-PAC-PAM絮凝材料的最佳原料组分质量配比为m(AT)∶m(PAC)∶m(PAM)=100∶20∶0.2;材料改性后铝离子含量增加、表面积增加、孔径增大、空隙增多,使得吸附能力增强;在相同实验条件下,AT-PAC-PAM(20%)除浊除藻效果最优,其最佳条件为pH =7、复合絮凝材料质量浓度为60 mg·L⁻¹、藻液初始浊度50 NTU、慢搅转速100 r·min⁻¹、慢搅时间20 min、沉淀时间30 min;在对絮体微观观察中发现,复合絮凝材料AT-PAC-PAM加强了吸附架桥和网捕作用,使所形成的絮体密集紧实,从而促进藻-土复合絮体的沉降,具有很好的应用前景。     

Amendment of hydroxyapatite in reduction of tetrachloroethylene by zero-valent zinc: its rate enhancing effect and removal of Zn(II)

The effects of hydroxyapatite (HAP) on dechlorination of tetrachloroethylene (PCE) by zero-valent zinc (ZVZ) were examined in batch systems. PCE was primarily transformed to trichloroethylene by ZVZ, with 1,2-trans-dichloroethylene representing a minor product. Dechlorination of PCE was accelerated by the presence of HAP, and the pseudo-first order rate constants increased with increasing amount of HAP. Zn(II), mostly generated from oxidative dissolution of ZVZ by PCE, was effectively removed from the solution by HAP. Ion substitution, coprecipitation, and adsorption are proposed as the possible mechanisms for Zn(II) removal. These reactions appeared to occur simultaneously and the contribution of each reaction to overall removal of Zn(II) was primarily dependent on HAP loading at constant ZVZ loading. The results indicate that the use of HAP in combination with conventional zero-valent metals is promising in that it can achieve both degradation of organic contaminants and stabilization of inorganic contaminants.     

Stormwater quality benefits of a porous friction course and its effect on pollutant removal by roadside shoulders.

This project has two main objectives; the first is to documents the effect of a porous friction course overlay on the quality of highway stormwater runoff, and the second is to assess pollutant removal of a vegetated area along the side of a road from both conventional and porous pavements. The quantity and quality of stormwater runoff from a four-lane divided highway in the Austin, Texas, area was monitored before and after the installation of a porous friction course (PFC). Observed concentrations of suspended solids and pollutants associated with particulate material were much lower in the runoff from the PFC compared with runoff from the conventional asphalt surface. The vegetated highway shoulder reduced the concentrations of many stormwater constituents from the conventional asphalt surface; however, the concentrations of these constituents in runoff produced by the PFC were so low that the vegetated area produced no further reduction in concentration.     

Montmorillonite-Cu(II)/Fe(III) oxides magnetic material as adsorbent for removal of humic acid and its thermal regeneration

In this work, the adsorption features of montmorillonite and the magnetic properties of Cu(II)/Fe(III) oxides were combined in a material to produce magnetic adsorbent, which can be separated from the medium by a simple magnetic process after adsorption. The magnetic material is effective for the removal of humic acid. At pH 6.1, 96% removal was observed from 4.4 mg l(-1) humic acid solution containing 0.02 M NaCl. The adsorption is pH and ionic strength dependent. Adsorption is favored at lower pH values and dissolved NaCl can enhance the adsorption. The adsorption mechanism of humic acid to the magnetic material was suggested to be the ligand exchange reaction between carboxylic groups of humic acid molecules and the magnetic material surface. The magnetic material can be thermally regenerated. The temperature and time required to achieve good regeneration efficiency were determined to be 300 degrees C and 3 h, respectively. The regenerated adsorbent is still magnetic and approximately has as high specific saturation magnetization and good adsorption capacities as the as-prepared adsorbent.     

Assessment of uncertainties in a long range atmospheric transport model: Methodology, application and implications in a UK context

Acid deposition models are inherently simplified representations of real world behaviour and their performance is best evaluated by comparison with observations. National and international acid rain policy assessments handle observed and modelled deposition fields in different ways. Here, both the observed and modelled deposition fields are seen as uncertain and the Generalised Likelihood Uncertainty Estimation (GLUE) framework is used to choose acceptable sets of model input parameters that minimise the differences between them. These acceptable sets of model parameters are then used to estimate deposition budgets to the UK and to provide a probabilistic treatment of excess deposition over environmental quality standards (critical loads).     

The effect of limited aeration on swine manure phosphorus removal.

Two low level aeration schemes (intermittent vs. continuous) were investigated on a laboratory scale, in conjunction with swine manure pH adjustment using sodium hydroxide (1.0 M), for manure phosphorus (P) removal. According to the data, an 80% reduction in soluble P was observed when the manure pH was increased to 8. Both intermittent and continuous aeration treatments could raise manure pH above 8 with an airflow rate of 1 L/minute in a period of 15 days. A drastic increase in pH (about 1 unit) was observed for both aeration schemes within the first day of test, resulting in a 76% reduction in soluble P concentration in the liquid. It appeared that there is no difference in terms of P removal between the two aeration programs, suggesting that the intermittent aeration be preferred to save energy while still achieving the same level of P removal.     

The effect of triethylene tetramine upon the selective removal of nickel (II), iron (II), manganese (II) and tin (II) in rats

The distribution of Nickel-63, Iron-59, Manganese-54 and Tin-113 in plasma was studied in rats which received single intravenous (i.v.) injection of aqueous solutions of their salts alone, and in rats which also received single intramuscular (im) injection of triethylene tetramine (TETA). TETA was extremely effective in reducing the plasma concentration of Nickel-63 followed by that of Iron-59, Manganese-54 and Tin-113.     

过硫酸盐在岩溶管道地下水中的稳定性及其对苯系物的去除效果

原位化学氧化(in situ chemical oxidation,ISCO)是一种高效便捷的去除地下水有机污染物的技术,相比于多孔介质,岩溶地下河中ISCO技术应用还未见报道.为了更好地认识ISCO技术在岩溶地下河石油污染修复中应用的可行性,使用过硫酸盐(persulfate,PS)作为化学氧化剂,在实验室利用碳酸盐...     

A screening model-based study of transport fluxes and fate of airborne mercury deposited onto catchment areas.

Dynamics of airborne mercury deposited onto catchment areas is investigated within the framework of a simulation model. Model results show that, for a particular atmospheric deposition rate, significant interannual variability in mercury transport flux in catchments is caused by climatology and corresponding differences in catchment soil loss rates; in comparison to the normal year, runoff flux increased by a factor of 2-3 for the wet year (rainfall 35% above normal) while for the dry year (rainfall 18% below normal) runoff flux decreased by factors of 5-7. The interaction of parameters describing soil type, topography and vegetation cover causes variability in both transport and emission fluxes among catchments; as soil loss rate increases by a factor of 5 due to variations in these parameters among the examined catchments, annual average transport flux increases by a factor of 3; and annual average emission flux of mercury (as Hg0) from soil to the atmosphere decreases by a factor of 2 due to the decreased levels of soil mercury associated with catchment soil loss increases. Seasonal variability of transport flux is associated with seasonal changes in precipitation and soil loss rates while seasonal changes of emission flux are primarily due to changes in soil moisture regime and temperature. Although modeled results are consistent with observational data from previous studies, they must be interpreted in a relative sense due to the screening-level character of this study.     

异养硝化细菌Alcaligenes sp.S3除氮特性及动力学

从湘江生活污水排污口分离纯化的一株菌Alcaligenes sp.S3,在氨氮浓度为400 mg/L时,经过192 h的降解,氨氮的去除率达到88%,并且NH2OH和NO2--N并没出现积累。在对不同浓度的氨氮进行一级动力学拟合时发现,只有氨氮浓度较高时才很好地符合,浓度为500 mg/L时R2达到0.9923。酸性环境对Alcaligenes sp.S3生长有抑制作用,在pH7.5～10生长较好。摇床转速对Alcaligenes sp.S3除氮影响不大,C/N过低或过高对Alcaligenes sp.S3除氮都有影响。     

改性HDPE填料的制备及对MBBR脱氮除磷效果的强化

为解决传统填料亲水性差、挂膜速度慢等问题,对高密度聚乙烯(HDPE)填料进行亲水改性并改善填料的挂膜性能及在移动床生物膜反应器(MBBR)中的应用效果,用浸涂的方式将纳米SiO₂、聚乙烯醇(PVA)、聚多巴胺(PDA)等材料涂覆在HDPE填料表面,对改性后填料进行接触角、SEM、FT-IR和XPS表征以及MBBR挂膜启动实验,研究化学需氧量(COD)、氨氮(NH₃-N)、总氮(TN)、总磷(TP)的去除效果以及对填料挂膜时间、生物膜量、蛋白质和多糖含量的影响。结果表明：改性后,填料接触角由94.82°降至 60.1°,填料亲水性明显增强;填料表面出现褶皱,粗糙度增加;上述材料成功负载在填料表面并引入了亲水基团且未改变填料基本结构;填料挂膜时间由25 d提前至16 d,挂膜时间提前了9 d,COD、NH₃-N、TN、TP去除率分别达到94.9%、95.4%、83.5%、71.6%,与改性前比分别提高了9.3%、6.7%、13.7%、11.5%;填料的生物膜量是改性前的1.57倍,从27.35 mg·g⁻¹提高到42.87 mg·g⁻¹,其中蛋白质和多糖的含量分别从改性前的6.48 mg·g⁻¹和3.38 mg·g⁻¹提高到8.83 mg·g⁻¹和5.82 mg·g⁻¹,分别为改性前的1.36倍和1.72倍。由此可以看出,表面涂覆可以提高HDPE填料的亲水性,改性后的HDPE填料可以缩短在MBBR中的挂膜时间及强化对COD、NH₃-N、TN、TP的去除效果。本研究结果可为HDPE填料亲水改性的深入研究及在MBBR中的实际应用提供参考。     

微生物复合固定化颗粒特征分析及去除河水氨氮效果的研究

以炉渣和改性玉米芯2种基质作为吸附材料,海藻酸钠(SA)和聚乙烯醇(PVA)2种包埋剂为基本骨架,微生物为降解主体,制备得到微生物复合固定化颗粒,并分析了颗粒的物理特征、活性恢复方式、对河水中氨氮和其他氮素的去除效果。结果表明:添加不同吸附基质对固定化颗粒的影响不同;实际河水驯化是有效的活性恢复方式;微生物复合固定化颗粒反应24h后,河水中氨氮降至1mg/L以下,河水中氨氮、亚硝态氮、硝态氮和TN去除率均在90%左右,对河流中氮污染的治理有一定的意义。     

Immission patterns of airborne pollutants in Argentina and Germany II. Biomonitoring of organochlorine compounds and polycyclic aromatics

The air pollution profiles of organic xenobiotics (including chlorinated insecticides and benzenes, PCBs and PAHs) were comparatively analyzed in the climatically different regions of Leipzig-Halle (Germany) and Greater Mendoza (Argentina) using two-year-old pine needles (Pinus sylvestris L.) as passive biomonitors. In addition to total compound contents, the levels of potentially bioavailable fraction in the inner needle compartment were determined. The peak levels of chlorinated insecticides and PAHs in an urban park in Mendoza were found to exceed the maximum levels in the Leipzig-Halle region by one to two orders of magnitude, indicating the recent substantial tropospheric input of the compounds from local sources. Bioavailable fractions were observed to exhibit considerable variations for some of these compounds, which became even more distinct when needle samples from Germany and Argentina were compared. Generally speaking, an increase in permeability under semiarid climatic conditions was observed for most of the xenobiotics examined. The discussion of the results reflects the problems associated with using biomonitoring for semivolatile compounds. Interpretation takes into account pollution measurements in the air at Argentine and German reference sites.     

The effect of coupled transport phenomena in the Opalinus Clay and implications for radionuclide transport

In this study, the potential effects of coupled transport phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay in Switzerland, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), are addressed. The solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters. shows that thermal osmosis is the only coupled transport mechanism that could, on its own, have a strong effect on repository performance. Based on the results from the analytical model, two-dimensional finite-difference models incorporating advection and thermal osmosis, and taking conservation of fluid mass into account, have been formulated. The results show that, under the conditions in the vicinity of the repository at the time scales of interest, and due to the constraints imposed by conservation of fluid mass, the advective component of flow will oppose and cancel the thermal-osmotic component. The overall conclusion is that coupled phenomena will only have a very minor impact on radionuclide transport in the Opalinus Clay, in terms of fluid and solute fluxes, at least under the conditions prevailing at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years).