Effects of acidic deposition on the erosion of carbonate stone — experimental results from the U.S. National Acid Precipitation Assessment Program (NAPAP)

One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30° to horizontal at the five NAPAP materials exposure sites range from ∼ 15 to ∼ 30 μm yr⁻¹ for marble, and from ∼ 25 to ∼ 45 μm yr⁻¹ for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ∼ 30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ∼ 70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide (“clean rain”). These results are for marble and limestone slabs exposed at an angle of 30° from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60° or 85°. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC, and Steubenville, OH.     

Studies on the effects of air pollution on limestone degradation in Great Britain

The CEGB and the Cathedrals Advisory Commission for England formed a Joint Working Party in 1985 to promote a research programme aimed at improving the understanding of the relationships between stone decay, atmospheric pollution and other factors. The programme has included exposure of limestone samples at York Minster and eight other sites in England and Scotland selected to give a mix of urban, marine and rural locations. All of the sites have comprehensive air pollution and meteorological monitoring and measurement of rainfall chemistry. At two sites samples have been fumigated with controlled levels of sulphur dioxide.Over all sites, there was a significant trend to increased weight loss with increase in average sulphur dioxide concentration, but a negative trend with total nitrogen oxides and with nitrogen dioxide. For sample exposures longer than 200 days, the sulphur dioxide dependence at the inland Liphook fumigation site was about half that found near the coast at Littlehampton. There was no significant trend to increase weight loss with total rainfall amount for the complete data set, but the analysis was dominated by the very wet Scottish site, which experienced the lowest average concentrations of air pollutants.A theoretical model for the chemical dissolution of rainwashed limestone has been derived from consideration of the ion and mass balances between the incident rain water and run-off water. The model has been fitted to the measured loss rates from the stonework field trials. With the exception of the very wet Scottish site, the difference between the stone loss rate, calculated from the model, and the mean measured loss rate for any particular exposure was generally smaller than the variation between the triplicate samples. Variation in the dry deposition velocity between sites and exposure periods does not appear to have been a very significant factor, and no residual effect due to the concentrations of nitrogen oxides was found. The natural solubility of limestone in water was the dominant term in describing the stone loss, and neutralization of the rainfall acidity the least significant. The volume of the intercepted rainfall and the variation in the pH of the run-off water with rainfall intensity have been identified as the two most significant terms which require more precise quantification. The data from the inland fumigation site used in the model predict a stone loss due to sulphur dioxide in the air of less than 1 μm yr⁻¹ surface recession per ppb SO₂.     

Communities of different plant diversity respond similarly to drought stress: experimental evidence from field non-weeded and greenhouse conditions

Accelerating rate of species loss has prompted researchers to study the role of species diversity in processes that control ecosystem functioning. Although negative impact of species loss has been documented, the evidence concerning its impact on ecosystem stability is still limited. Here, we studied the effects of declining species and functional diversity on plant community responses to drought in the field (open to weed colonization) and greenhouse conditions. Both species and functional diversity positively affected the average yields of field communities. However, this pattern was similar in both drought-stressed and control plots. No effect of diversity on community resistance, biomass recovery after drought and resilience was found because drought reduced biomass production similarly at each level of diversity by approximately 30?%. The use of dissimilarity (characterized by Euclidean distance) revealed higher variation under changing environments (drought-stressed vs. control) in more diverse communities compared to less species-rich assemblages. In the greenhouse experiment, the effect of species diversity affected community resistance, indicating that more diverse communities suffered more from drought than species-poor ones. We conclude that our study did not support the insurance hypothesis (stability properties of a community should increase with species richness) because species diversity had an equivocal effect on ecosystem resistance and resilience in an environment held under non-weeded practice, regardless of the positive relationship between sown species diversity and community biomass production. More species-rich communities were less resistant against drought-stressed conditions than species-poor ones grown in greenhouse conditions.     

麦饭石对水溶性染料及印染废水吸附的研究

研究了麦饭石对水溶性染料直接耐酸大红4BS的吸附作用,探讨了搅拌时间、麦饭石粒度、投料量及溶液pH值等因素对吸附的影响。结果表明,麦饭石对染料的吸附能较好地符合Langmuir方程。且对染料溶液及实际废水具有良好的脱色率和COD去除率。     

浙江湖州及邻区地貌与环境地质问题分析

浙江湖州及邻区地貌总体特征是以平原为主，丘陵次之，本文在讨论了影响区域地貌发育因素的基础上，对平原区和丘陵区的次级地貌单元进行了划分并作了总结。详细分析了区内不同地貌单元下存在原生和受人类经济活动影响出现的环境地质灾害问题，指出原地生质－地貌条件下区域环境地质问题（如地壳稳定性，软土地基，地下水水质，土壤渍害，水土流失等），大多数对人类社会影响不大或者已经有了相应的防治对策，但是，受人类经济活动影响，人为的或人工诱发的环境地质问题则越来越严重，如平原区由于过量开采地下水出现的地面沉降，丘陵区由于开采石矿引起的景观破坏，水土流失，岩溶塌陷和滑坡等地质灾害。     

麦饭石对水溶液中铜离子的吸附作用研究

研究了麦饭石对水溶液中铜离子的吸附作用。其吸附率与粒度、用量、铜离子溶液、溶液的ｐＨ值和吸附时的温度等因素有关，比较了相同实验条件下麦饭石和活性炭的吸附能力，提出了工业应用的适宜条件。     

Meteorologically adjusted ozone trends in urban areas: A probabilistic approach

A method has been developed that explicitly accounts for the effect of meteorological fluctuations on the annual distribution of ground-level ozone in urban areas. The model includes a trend component that adjusts the annual rate of change in ozone for concurrent impacts of meteorological conditions, including surface temperature and wind speed. The model was applied using available data from 43 urban areas throughout the U.S.A. where ozone levels frequently exceed the National Ambient Air Quality Standard. The results suggest that meteorologically adjusted upper percentiles of the distribution of daily maximum 1-h ozone are decreasing in most urban areas over the period from 1981 to 1991. The median rate of change was −1.1% per year indicating that ozone levels have decreased approximately 11% over this time period. Trends estimated by ignoring the meteorological component appear to underestimate the rate of improvement in ozone primarily because of the uneven year-to-year distribution of meteorological conditions favorable to ozone.     

环境污染加剧石质文物风化:机理、过程及防护措施

石质文物的风化问题由来已久,在影响石质文物风化的各类因素中,环境恶化对石质文物的风化影响日益严重,但现有研究大多忽略了环境污染加剧的影响。在此背景下,本文从酸性气体排放、温度效应和水体污染三个方面阐述了环境污染加剧对石质文物风化的影响和作用机理,并对现有石质文物的防护措施进行综合比较分析,提出石质文物的保护建议和措施,为新形势下石质文物的保护研究提供新的思路。     

HTPB推进剂老化性能湿热影响分析

目的 掌握HTPB推进剂老化过程中,温度和湿度对其力学性能的影响及贡献程度.方法 对HTPB推进剂进行不同湿热条件下的加速老化试验,并测量不同老化时间推进剂的质量损失分数和力学性能,结合推进剂在温度和湿度下的作用机理,对质量损失分数随老化时间的变化规律进行分析,以最大拉伸强度作为性能指标,对HTPB推进剂湿热老化过程进行湿热双因素方差分析.结果 湿度对HTPB推进剂质量损失分数的影响起主导作用,在75％～85％有一个湿度拐点值,大于或小于这个拐点值,推进剂遵循不同的质量损失分数变化规律.温度和湿度对推进剂最大抗拉强度方差分析的F值均大于其临界值,影响显著.相比而言,湿度的影响更加显著,整个老化过程中,温度和湿度的影响作用表现出先增加、后下降的趋势.温湿交互作用在试验前期和后期对推进剂的影响不显著,而在试验中期较为显著,同样呈现出先增大、后减小的规律.结论 湿度对推进剂最大拉伸强度影响的贡献率最大,温度次之,交互作用最小.从时间轴上看,湿度的贡献率表现为单调递增趋势,温度为单调递减趋势,交互作用呈现抛物线趋势.     

吸附VOCs活性炭真空热再生及影响因素实验

活性炭的再生及循环利用对降低吸附法治理含VOCs废气的成本、减少危废产生量具有重要意义。采用真空热再生法对吸附乙酸乙酯的活性炭进行了再生实验,考察不同再生温度及保温时间对活性炭再生效果的影响及真空热再生法对活性炭的循环再生性能。结果表明:活性炭的损失率随再生温度升高而增大,并且当再生温度<200 ℃时,活性炭损失率最大仅0.7%;在最佳实验条件(200 ℃并保温30 min)下,乙酸乙酯脱附率达到93.8%,再生后活性炭的平衡吸附量为108.1 mg/g。比表面积及孔径分布显示,200 ℃以下的真空热再生对活性炭结构几乎无影响;300,400,500 ℃下真空热再生后活性炭的比表面积较新活性炭分别增加22,19,42 m2/g。在最佳再生条件下循环再生6次后,活性炭对乙酸乙酯的平衡吸附量达到新活性炭的97%,表明真空热再生法对活性炭具有良好的再生性能。     

α-Fe2O3催化臭氧氧化处理苯酚废水的效果及机理

催化臭氧氧化工艺是处理难降解废水的有效手段,但仍存在臭氧利用率较差、催化效率低、催化剂活性组分流失等问题. 本文以α-Fe₂O₃作为臭氧催化剂,通过SEM、N₂吸附/脱附等方法表征了α-Fe₂O₃的结构,构建了α-Fe₂O₃催化臭氧氧化处理苯酚废水体系,优化催化条件,提高处理效率,并对催化机理和催化剂稳定性进行了深入讨论. 结果表明:①α-Fe₂O₃表现为团聚的不规则球状,且比表面积较大,达83.38 m2/g,具有良好的臭氧催化潜力. ②臭氧投加量和pH对催化体系的影响明显,但α-Fe₂O₃投加量的变化对降解效果的控制并不显著,在优化的条件下反应30 min时COD的去除率可达97.67%,较单独臭氧提高了41.33%. ③在催化臭氧氧化中投加TBA和Na₃PO₄分别屏蔽·OH和路易斯酸性位点后,COD的去除率分别降低了17.01%和20.92%,这表明在α-Fe₂O₃表面的路易斯酸性位点产生的·OH是COD去除率高的主要原因. ④α-Fe₂O₃在重复试验中保持了较高的催化活性和稳定性,6次重复后对COD的去除率仍可达到93.07%,流失率为1.05%. 研究显示,α-Fe₂O₃表现了优异的臭氧分解协同作用,具有良好的苯酚持续去除能力和结构稳定性,可为高效去除含酚废水或难降解废水提供技术参考.      

南京至安庆铁路铜陵至池州段水土保持预测分析

水土流失是开发建设项目活动中对环境产生较常见的负面影响。文章采用类比法对南京至安庆铁路铜陵至池州段的铁路建设过程中产生的水土流失量进行预测。结果表明,铜陵至池州段铁路建设过程中扰动原地貌面积363．62hm^2,土石方总量631．18×10^4 m^3。施工期和自然恢复期造成水土流失量74688t。并针对水土流失产生的危害提出了有针对性的防治措施。     

Gypsum accumulation on carbonate stone

The accumulation of gypsum on carbonate stone has been investigated through exposure of fresh samples of limestone and marble at monitored sites, through examination of alteration crusts from old buildings and through laboratory experiments. Several factors contribute to gypsum accumulation on carbonate stone. Marble or limestone that is sheltered from direct washing by rain in an urban environment with elevated pollution levels is likely to accumulate a gypsum crust. Crust development may be enhanced if the stone is porous or has an irregular surface area. Gypsum crusts are a surficial alteration feature; gypsum crystals form at the pore opening-air interface, where evaporation is greatest.     

红色旅游资源地游客国家认同的影响因素与多元路径研究——基于模糊集定性比较分析

红色旅游资源及其开发具有个体和群体意义,是国家认同实现的重要途径。采用多变量交互作用的模糊集定性比较分析方法,以游客国家认同为结果变量,构建社会记忆（人物记忆、环境记忆、时间记忆、空间记忆）、景区形象（吸引物形象、设施环境形象、文创宣传形象）、旅游体验、感知价值为前因变量,探索影响国家认同的前因条件组合与多元路径。研究结果表明：（1）对于单项因素来说,虽然人物记忆的一致性相对较高,但所有单因素都无法构成国家认同的充要条件。（2）9个变量共产生512种条件组合,满足条件的路径组合共11条,总体覆盖率为0.8916,构成了空间环境模式、形象价值模式、历史体验模式和时间综合模式四大类路径模式。（3）人物记忆出现在所有路径组合中,且所有组合同时包含至少一个社会记忆下的其他的二级维度,例如环境、时间或空间记忆。当社会记忆的四个二级维度全部出现时,产生了原始覆盖率最高的路径组合。（4）在原始覆盖率大于20%的6条路径中,都同时包含社会记忆和景区形象中的二级要素;在原始覆盖率小于20%的5条路径中,皆“一定不包含”设施环境形象。本文为红色旅游目的地在新格局下的高质量发展提供了理论参照。     

石煤渣保温材料的配方研究

以石煤渣为主要原料研制应用于工业窑炉的保温材料，具有较高的耐压强度和使用温度，导热率低。本文通过分析各原料的主要作用，研究了不同原料掺量对材料性能的影响，从而得到了石煤渣保温材料合理的配方范围为：石煤渣４０％～６０％、可燃造孔物３０％～４０％、粘结剂１２％～２０％、外加剂０．１０％～０．２０％。     

Selection of Optimal Superfinishing Parameters

This paper is concerned with the selection of optimal superfinishing conditions. During superfinishing of cylindrical surfaces, an axially oscillating abrasive stone is pressed against a rotating workpiece. Experimental results are presented that show the effect of contact pressure, process kinematics, and grit size on superfinishing behavior. An optimal contact pressure is found at which the removal rate is maximized. The ratio of axial oscillation frequency to workpiece rotational frequency should be selected so as to avoid integer values, which result in low stock removal, and half values, which can lead to lobe formation. Finer grit stones provide smoother surface finishes but less stock removal; therefore, the grit size selected should be only fine enough to generate the required surface roughness.     

大巴山区早古生代地层和石煤中硒的化学活动性的初步研究

通过对大巴山区主要分布的早古生代地层中的碎屑岩，碳酸盐岩和石煤的原岩，风化岩，原生土壤的硒含量及其相关关系分析，及对南秦岭早古生代地层和石煤中硒的化学活动性进行了研究。结果表明：其岩石和石煤中的硒在地层环境下有较大的活动性，不同类型岩石中硒淋失率和硒的淋失量不同，富硒而淋失率低但淋失量高的下寒武统鲁家坪组和早志留世大贵坪组的炭质板岩和石煤的分布区土壤（主要为当地岩石的风化残积物）的含硒量可达10mg/kg，甚至更高，是大巴山的富硒带和硒中毒带，含硒低而且淋失率高的志留系砂岩和粉砂岩以及寒武系统砾屑灰岩分布区是大巴山区的低硒带。     

中国生物多样性变化趋势分析

在生物多样性受到严重威胁前提下,为评估中国生物多样性保护的成效,引入了世界自然保护联盟(IUCN)开发设计的红色名录指数(Red List Index,RLI),结合我国实际情况修订后,计算脊椎动物和维管植物的红色名录指数。结果显示,以均值法(Equal-steps method)计算的脊椎动物RLI有所上升,脊椎动物整体多样性丧失速率下降;而以灭绝风险法(Extinction risk method)计算的脊椎动物RLI有所下降,表明有部分高濒危等级的脊椎动物物种进一步丧失;两种方法计算的维管植物RLI均有所下降,说明维管植物多样性丧失速率加快;而基于均值法计算的维管植物RLI下降速率更快,说明数量较多的物种丧失速率加快,亟需加强保护。这是RLI在国家水平上进行应用,也是在国家水平上对RLI指数进行验证,计算结果将为我国生物多样性保护提供参考。     

Stone degradation due to dry deposition of HCl and SO2 in a laboratory-based exposure chamber

The role of the gaseous pollutants, HCl and SO₂, has been investigated in a laboratory-based atmospheric flow rig. Using an HCl level of 25 ppm at a pollutant bulk presentation rate 10 times that found typically outdoors, a degradation acceleration factor of about 20 times was obtained, together with realistic degradation products. HCl was found to be a more reactive gas than SO₂, which was also studied at the 25 ppm level. This may be due either to factors involved in the adsorption of the gases on to the stone surfaces, or the extensive solubility of HCl, or the requirement of an extra step in the conversion of SO₂ to sulphate, which would limit the overall reaction rate. The soluble degradation product CaCl₂ is readily washed off the stone allowing continuous reaction, while the relatively insoluble CaSO₄.2H₂O can remain on, or in the stone surface regions and may inhibit or affect further reaction with SO₂.The reaction of limestone with HCl gas is mass-transport limited and greater material losses arise in locations of higher HCl concentration and deposition velocity, i.e. a close-to-source effect is highlighted due to its high solubility and reactivity, but the HCl concentration is, of course, generally about one-fiftieth of that of SO₂ outdoors. For SO₂, with lower solubility and a necessary oxidation stage to form SO₄²⁻, comparatively high deposition velocities are applicable more widely from the source. The consequences include a widespread formation of relatively insoluble CaSO₄.2H₂O and consequent crust development.     

Preliminary results from the analysis of metal samples from the National Materials Exposure Programme (NMEP)

As part of a U.K. National Materials Exposure Programme, samples of stone and metals are being exposed at 29 sites for a minimum of 4 years. The sites were chosen to cover a wide range of environmental conditions, climate and topography. Information on meteorological conditions and atmospheric pollutants are being collected from all the sites. Four of the sites also form part of an international programme that is operating concurrently for the United Nations Economic Commission for Europe (UNECE).Results are reported from the exposure test on bare mild steel, galvanized steel, painted steel, copper and aluminium. Rates of corrosion in industrial areas are well below those reported for similar sites in 1930–1960, mainly because of the large fall in sulphur dioxide concentrations, and in many cases the scale is becoming increasingly protective. Rates for aluminium are extremely low.The measured mass losses have been fitted to a variety of simple multivariate correlation functions. Work using continuous corrosion monitors suggests (in agreement with the mass-loss data) that:

1. 1.(i) the rate of corrosion of steel is controlled in British conditions mainly by the long-term average sulphur dioxide concentration, and scarcely responds to short-term SO₂ episodes;
2. 2.(ii) nitrogen oxide concentrations have little effect on the rate of corrosion;
3. 3.(iii) the chloride content of rain is not a very important factor for steel corrosion rates except at a few coastal sites.