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.     

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.     

Mercury transportation in soil via using gypsum from flue gas desulfurization unit in coal-fired power plant

The mercury flux in soils was investigated, which were amended by gypsums from flue gas desulphurization (FGD) units of coal- fired power plants. Studies have been carried out in confined greenhouses using FGD gypsum treated soils. Major research focus is uptakes of mercury by plants, and emission of mercury into the atmosphere under varying application rates of FGD gypsum, simulating rainfall irrigations, soils, and plants types. Higher FGD gypsum application rates generally led to higher mercury concentrations in the soils, the increased mercury emissions into the atmosphere, and the increased mercury contents in plants (especially in roots and leaves). Soil properties and plant species can play important roles in mercury transports. Some plants, such as tall fescue, were able to prevent mercury from atmospheric emission and infiltration in the soil. Mercury concentration in the stem of plants was found to be increased and then leveled off upon increasing FGD gypsum application. However, mercury in roots and leaves was generally increased upon increasing FGD gypsum application rates. Some mercury was likely absorbed by leaves of plants from emitted mercury in the atmosphere.     

酸雨对红色石灰土壤中Ca2+迁移及岩溶土壤生态系统的影响

为探讨酸雨对粤北岩溶区岩溶土壤中Ca迁移和流失的影响,选择酸雨频率和酸雨程度较高的我国广东省佛山市,开展自然降雨对红色石灰土壤中Ca2+的流失影响试验,于2011—2013年共收集到61次有效降雨产生的渗漏液,分析渗漏液中ρ(Ca2+)的变化情况,并间隔0.5 a左右测定供试土壤中的w(水溶性Ca)和w(TCa)(TCa为全钙),将试验3 a后供试土壤的w(有机质)、w(TN)、pH与供试源地土壤进行比较. 结果表明:①单位降雨造成的红色石灰土壤中Ca2+流失量与渗漏液中ρ(Ca2+)呈极显著正相关,与降雨量、渗漏液pH均呈正相关,而与雨水pH呈负相关,但不显著;单位降雨造成的土壤Ca2+净流失量达到2.16×10-5 g/(mm·kg),61次有效降雨造成的Ca2+净流失总量为0.05 g/kg. ②与蒸馏水及石灰岩采样点所在的坡麓洼地积水比较,酸雨明显增加了红色石灰土壤Ca2+流失量,但其影响因素复杂. pH为4.50~<5.65的轻度酸雨造成的土壤Ca2+流失量最大,其次是pH为5.65~6.29的非酸雨和pH<4.50的重度酸雨. ③降雨使石灰土壤中的w(TCa)呈持续减少趋势,2011—2013年供试石灰土壤中w(水溶性Ca)减少量为0.36 g/kg,并且呈明显的由上至下的减少迁移过程. ④与供试源地土壤相比,历经3 a酸雨淋溶的红色石灰土壤的w(有机质)和w(TN)均极显著增加,表层pH也极显著升高,意味着酸雨加速了土壤的分解转化,存在潜在的养分流失风险. 研究显示,酸雨不仅造成石灰土壤中Ca2+的加速流失和迁移,也加速了土壤中各类养分的分解转化,同时还会对岩溶地形、岩溶植物、流域水环境产生潜在或直接的影响.      

Advertent/inadvertent effect on ‘rainfall center’ displacement in Northern Israel

This study of cloud seeding and urbanization effects on the spatial rainfall distribution was carried out in two stages. In the first stage the location of a ‘rainfall center’ (the area with the rainfall maximum) for annual amounts of rainfall was established by applying the Distance Correlation Matrix (DISTCORMAT) technique. Besides ‘natural’ climatic fluctuations there are two other factors which could also cause a shift in the ‘rainfall center’, namely, cloud seeding operations and the inadvertent urban influences. Rainfall centers were computed for the two experimental cloud seeding periods and for a subsequent period of operational seeding.Comparison of the DISTCORMAT outputs revealed that the ‘rainfall centers’ are located, as expected, in the Upper Galilee for the first experimental period and later were displaced westward by 2–4 km. Since in the second random experiment the seeding flight route and target area were shifted eastward, it seems that there is no evidence supporting the cloud seeding rainfall excess determined by various statistical methods. However, it is possible to attribute the center's displacement to the massive urbanization process along the Mediterranean coastal plane.In the second stage only 40 rain stations in the extreme northern part of the country were used and the DISTCORMAT was computed separately for ‘seeded days’ and ‘non-seeded days’. The results indicate that, although the center moved eastward on ‘seeded days’ during the second experiment, it moved westward for the ‘non-seeded days’ sample. Thus the finding offers evidence of both effects: advertent cloud seeding and the inadvertent urbanization factor.     

燃煤电厂脱硫石膏改良碱化土壤的施用量

利用燃煤电厂脱硫石膏改良盐碱地对于确保国家粮食安全和生态安全、发展循环经济具有重要意义. 选择具有典型代表性的宁夏西大滩碱化土壤,以降低土壤碱化度和总碱度为目标,采用盆栽试验和土柱模拟试验,确定了改良不同程度碱化土壤脱硫石膏的理论施用量:轻度碱化土壤为12 529.5 kg/hm2,中度碱化土壤为17 256.0 kg/hm2,重度碱化土壤为23 563.5 kg/hm2. 在脱硫石膏改良的碱化土壤上种植油葵的田间试验表明,由盆栽试验和土柱模拟试验得出的脱硫石膏施用量可以作为大田示范推广的参考值.      

Laboratory measurements of sulfur dioxide deposition velocity on marble and dolomite stone surfaces

The deposition velocity of SO₂ on marble and dolomite stone surfaces in a humid atmosphere was measured as a function of time in the laboratory using continuous monitoring techniques. The deposition velocity of SO₂ on marble varied between 0.02 and 0.23 cm s⁻¹, and was generally observed to decrease with time. The deposition velocity of SO₂ on dolomite varied between 0.02 and 0.10 cm s⁻¹, and gradually increased over the first 2000 ppm-h of exposure. For both types of stones, the deposition velocity increased significantly when condensed moisture was observed on the stone surface. Chemical analysis of the stone samples indicated that the SO₂ deposited reacted with the stone materials to form gypsum (CaSO₄·2H₂O) on the marble surfaces and gypsum and epsomite (MgSO₄·7H₂O) on the dolomite surfaces.     

湿法脱硫浆液中石膏与汞的结合特性模拟研究

燃煤烟气湿法脱硫石膏中汞的大量富集限制了其应用范围且容易产生汞的二次逃逸问题.因此,本文对脱硫浆液中的汞在固相石膏的迁移转化规律进行了模拟研究,考察了不同操作条件和离子浓度的影响,探求汞进入石膏的量和形态的变化趋势.同时考察了温度、p H、石膏老化时间和结晶方式等对汞与石膏结合特性的影响,并对机理进行了探讨.结果表明,当液相汞浓度从0.16 mg·L-1增加到2.67 mg·L-1时,进入石膏的汞含量相应从0.38 mg·kg-1增加到4.17 mg·kg-1,但其占液相总汞的比例却呈先下降后不变的趋势.当石膏浆液浓度从1%增加到20%时,由液相进入石膏中的汞比例不断上升,但石膏汞含量却不断下降.基于实验结果推测汞与石膏结合的两种方式:石膏的内部包裹作用和石膏的表面吸附作用.另外,酸根离子浓度会改变浆液中游离汞的含量,从而影响石膏中汞的富集量:Cl-和NO-3对汞进入石膏有抑制作用,而SO2-4的存在会起到促进作用;铁、铝阳离子的存在会促进汞进入石膏,钙、镁阳离子对汞的富集基本无影响.     

黔中喀斯特石漠化地区土壤温室气体浓度的时空分布特征

2006~2007年对喀斯特石漠化地区土壤剖面中CO2、N2O和CH4的浓度分布进行观测.结果表明,土壤剖面中CO2、N2O和CH4浓度分别介于530.2~31512.6、0.27~0.67和0.1~3.5μL.L-1.总体上,自地表向下,CO2和N2O浓度逐渐增大,CH4浓度则为逐渐减小,但在阴冷潮湿的10、11月和1月,15cm以下土层中CO2和N2O浓度随着深度的增加逐渐减小,CH4浓度则明显增加.土壤温度、水分同时影响剖面中CO2、N2O和CH4的时空分布,但影响效应以及作用的土层深度有所不同.相关分析结果表明,土壤中CO2和N2O浓度的时空分布显著正相关(r为0.780~0.894,p0.05~0.01),相关关系受环境因子的影响;CO2和CH4的时空分布则呈显著负相关关系(r=330,p0.01);N2O和CH4的空间分布为互逆关系,但只在土壤水分较大月份达到显著水平(r为-0.829~-0.956,p0.05~0.01).     

Movement and degradation of aldicarb residues in South Carolina loamy sand soil

The movement and degradation of aldicarb (2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxime) residues was measured in a Dotham loamy sand soil in Barnwell County in southern South Carolina. The experiment was designed to compare movement in a fallow plot versus a soya bean plot and to compare residue results from soil suction lysimeters and soil samples. The soil sample data indicate that aldicarb degraded at a rate corresponding to a half life of approximately 9 days with essentially no residues present 4 months after application. This degradation rate is faster than the 14–39-day half-life measured in nearby states. Because this relatively rapid degradation rate generally constrained residue movement to the upper 0.3 m in both plots (resulting in no significant residues in the lysimeters and monitoring wells), comparison between data from soil cores and suction lysimeters was not possible and the reduced evapotranspiration in the fallow plot had little effect on residue movement. Simulations using the unsaturated zone model PRZM with rainfall records from 15 years were used to illustrate that aldicarb residues should be limited to the upper 1.5 m, regardless of year-to-year variations in rainfall.     

烟气脱硫副产物的综合利用

通过分析烟气脱硫石膏的性能 ,介绍了脱硫石膏的利用情况和研究进展 ,利用脱硫石膏生产建筑材料 ,如 β石膏和α石膏的工艺日臻成熟 ,利用脱硫石膏生产水泥辅料已进入工业化 ,而利用脱硫石膏生产充填尾砂胶结剂已经完成试验阶段 ,脱硫石膏在农业上也有很广泛的用途。     

无机结垢对纳滤膜分离水中全氟化合物的影响

选取全氟辛烷磺酸(PFOS)和全氟丁烷磺酸(PFBS)两种链长不同的典型全氟化合物(PFASs)作为目标去除物,以硫酸钙为典型无机结垢,研究硫酸钙结垢不同阶段中纳滤膜去除PFASs的特征和相关机理,简称硫酸钙试验,同时以相同离子强度的非结垢无机盐溶液开展对比试验考察目标PFASs的截留规律.结果表明,当硫酸钙和目标PFASs共存时,PFOS稳定截留率为硫酸钙试验(97.1%)>对比试验(93.0%),而PFBS稳定截留率为对比试验(46.2%)>硫酸钙试验(38.2%).对于同一PFAS,同一过滤时刻,膜面带电量:硫酸钙试验<对比试验;联合截留率、膜通量和Zeta电位综合分析可知,硫酸钙结垢过程中,PFOS的截留主要由Ca²⁺与PFOS的络合及架桥作用控制,该作用影响PFOS分离过程中的空间位阻作用强度;PFBS过滤初期的截留中静电排斥起主要作用,结垢层生成后,滤饼层强化的浓差极化作用成为PFBS截留效果下降的主要原因.     

城市降雨径流监测自动采样技术研发与应用

海绵城市建设效果评估需要对海绵设施和不同尺度区域的径流过程进行水质监测采样。现有的采样方法和设备难以自动采集到径流产生初始阶段的水样。研发了一套包含无电力驱动天然降雨自动采样器、"零捕获"下垫面径流过程水质监测自动采样终端、智能型自动水质监测采样器等设备的城市降雨径流水质监测自动采样技术,解决了全天候、自动采集天然降雨和径流过程最初水样的难题,并可记录采样过程的具体时间。实际应用表明,该套技术可操作性强,性能可靠,能为相关科学研究和监测评估提供参考。     

水泥窑协同处置危废生产熟料的性能研究

取自华新水泥厂协同处理危废生产的水泥熟料,掺入5％的石膏进行球磨使比表面积达到350±10m^2／kg制备熟料样品,测定和分析了样品的矿物和化学成分以及其砂浆成型后的物理性能和浸出毒性。结果表明：熟料样品的矿物成分主要有硅酸三钙、硅酸二钙、铝酸三钙、铁铝酸四钙和石膏,并且凝结时间正常,强度达到52．5等级以上,对重金属有很好的固化作用,浸出毒性均远低于国标的限值。水泥窑协同处置危废对缓解生态环境的压力有很好的发展前景。     

烟气脱硫石膏及其建材资源化研究

介绍了作者在烟气脱硫石膏及其作为主要原料制备建筑石膏、粉刷石膏、石膏砌块（条板）、纸面石膏板、腻子、水泥缓凝剂、二水石膏胶结材等建材资源化方面的研究结果。结果表明，烟气脱硫石膏的品位较高，便于利用，是建材工业的宝贵资源，应进一步加大研究开发力度。     

Determination and assessment of total mercury levels in local, frozen and canned fish in Lebanon

Fish is an important constituent of the Lebanese diet. However, very little attention in our area is given to bring awareness regarding the effect of the toxicity of mercury (Hg) mainly through fish consumption. This study aimed to report analytical data on total mercury levels in several fish species for the first time in thirty years and to also made individuals aware of the presence and danger from exposure to mercury through fish consumption. Fish samples were selected from local Lebanese markets and fisheries and included 94 samples of which were fresh, frozen, processed, and canned fish. All values were reported as microgram of mercury per gram of fish based on wet weight. The level of mercury ranged from 0.0190 to 0.5700 μg/g in fresh samples, 0.0059 to 0.0665 μg/g in frozen samples, and 0.0305 to 0.1190 μg/g in canned samples. The data clearly showed that higher levels of mercury were detected in local fresh fish as opposed to other types thus placing consumers at higher risk from mercury exposure. Moreover, the data revealed that Mallifa (yellowstripe barracuda/Sphyraena chrysotaenia), Sargous (white seabream/Diplodus sargus), Ghobbos (bogue/Boops hoops), and shrimp (Penaeus sp.) were among the types containing the highest amounts of mercury. On the other hand, processed fish such as fish fillet, fish burger, small shrimp and crab are found to contain lower levels of mercury and are associated with lower exposure risks to mercury. Lebanese population should therefore, be aware to consume limited amounts of fresh local fish to minimize exposure to mercury.     

Determining the acidity and chemical composition of fog,haze and cloud droplets in Israel

The chemistry and acidity of individual droplets were analyzed in samples of fog, haze and cloud collected at Tel Aviv University on the Mediterranean seacoast and at the top of Mt Meron and of Mt Carmel in northern Israel. Acidity was measured using pH paper in a cascade impactor. The characteristics of droplets and interstitial particles 0.3–20.0 μm in size were identified using microspot and electron microscopy techniques.The results revealed the following: (1) the aerosols in the micrometer and sub-micrometer range were mostly very acidic droplets, with pH as low as 2.0, caused by the presence of sulfuric acid; (2) lower acidity was associated with an increase in droplet size, due to dilution by condensation or nucleation scavenging of mineral dust, i.e. gypsum, calcite and dolomite; (3) both acidic and alkaline droplets contained significant amounts of sulfur; and (4) the alkaline droplets contained minerals and salt solutions of Na₂SO₄, CaSO₄, or NaCl.     

An improved wet deposition map of the United Kingdom incorporating the seeder—feeder effect over mountainous terrain

Data of the mean annual rainfall at 4000 sites across the United Kingdom during the period 1986–1988 have been used. These were combined with measurements of the concentrations of principal ions in rainfall at 59 rural lowland sites. The data have been modified to account for the higher concentrations of ions dissolved in rain water measured in mountainous areas. This occurs due to the scavenging of polluted hill caps clouds by less-polluted raindrops. It was assumd that scavenged cloudwater concentrations were double those of the local rainfall. The results show that the annual deposition by rainfall of pollutant ions over high ground is much higher than had previously been thought. Relative to the original scheme, which assumed ion concentrations were constant with height, the new scheme calculated increases in deposition of up to 76%. Rainfall was found to be more polluted near the east coast of Britain. However, the highest annual pollutant deposition by rainfall occurred in the mountainous regions near the west coast, such as the Lake District and Snowdonia, due to the high rainfall in these areas.     

西安市极端降雨时间演变特征分析

全球气候变化导致城市洪涝灾害频发,极端降雨具有历时短、成灾快的特点,是造成城市内涝的主要原因,研究极端降雨的变化趋势,可为城市应对内涝提供参考。为分析西安市极端降雨事件的时间演变特征,采用滑动平均、线性回归、M-K突变性检验和Hurst指数分析等方法对西安市1990—2020年的降雨资料进行分析,得出西安市近30年降雨事件随时间的变化特征,并对未来变化趋势进行预测分析。结果表明:1）西安市年降雨量无明显变化趋势,但极端降雨量以每10年29 mm的速率呈增加趋势,并且在2002年突变性增加;2）极端降雨频次以每10年0.85次的速率呈增加趋势,并且在2014年突变性增加;3）极端降雨量和极端降雨频次的Hurst指数分别为0.974和0.893,具有较强的持续性,这表明两者变化趋势与过去相一致,未来西安市的极端降雨事件会呈持续增加趋势。     

兴文石林地质地貌景观的脆弱化趋势研究

兴文石林是喀斯特岩溶地质风景名胜区兴文石海的中心景区,喀斯特岩溶山地的生态环境具有一定脆弱特性,随着旅游业的不断发展,景区加大了开发力度,可能导致景区脆弱性的加剧,为了保证在旅游开发中能对景区重要的地质资源进行更好地保护,采用生态脆弱区评级指标及权重值评分法对兴文石林的10个主景点进行了研究,分析得出,兴文石林存在轻生态脆弱性、中生态脆弱性和强生态脆弱性三种梯度趋向,其中,脆弱性最强区域面积达到2平方公里的面积,这些区域分布在景区的边缘地带,因此,要实现旅游资源的可持续利用,必须对强生态脆弱性区域实行禁游和实行退耕还林等措施,以防止脆弱区域的扩大和脆弱性加剧.