Probing Hg evasion from surface waters of two Chinese hyper/meso-eutrophic reservoirs

Measurements of water/air exchange flux of gaseous elemental mercury (GEM) were conducted in a hyper-eutrophic reservoir and a meso-eutrophic reservoir in southwest China in both warm and cold seasons by using a dynamic flux chamber (DFC) method coupled with an automatic gaseous Hg analyzer. Both strong diurnal and seasonal variations of GEM fluxes were observed. The diurnal cycle of the GEM flux was more pronounced during sunny days compared to cloudy and rainy days, which highlights the effect of solar intensity on the GEM flux. GEM fluxes in warm seasons were considerably higher (2.5 to 4.1 times higher) than in cold seasons, which was attributed to the combined factors including meteorological factors, water quality parameters and water Hg concentrations. Clear variation in GEM fluxes was observed between the two reservoirs. Mean GEM fluxes in the hyper-eutrophic reservoir (WJD) (3.2-20.1 ng m⁻² h⁻¹) were significantly higher than those in the meso-eutrophic reservoir (SFY) (0.6-4.4 ng m⁻² h⁻¹). Evasion of Hg played a distinct role in the mass balance of Hg in the two reservoirs. In WJD, evasion was the second most important mechanism for Hg losses from the reservoir (17.5% of the total losses); whereas in SFY, loss of Hg via volatilization constituted an extremely little portion to the total losses of Hg (0.8%).     

Factors influencing the temporal diffusion of broadband adoption: evidence from Oklahoma

This paper examines the shifting influence of household characteristics and telecommunications infrastructure on the residential broadband adoption decision for Oklahoma residents between 2003 and 2006. In particular, the spread of wired telecommunications infrastructure (namely cable Internet and Digital Subscriber Lines (DSL)) is examined, along with the effect that this diffusion has had on broadband access rates. The data indicates that the gap in broadband access rates between rural and urban areas has remained relatively constant over this period despite increased levels of cable and DSL throughout the state. In addition, an inter-temporal decomposition shows that the increasing levels of infrastructure are not the dominant cause of higher broadband rates over time. Instead, shifting returns to specific characteristics (namely income) are found to be the primary contributors.     

Spatial distribution of total Hg in urban soils from an Atlantic coastal city (Aveiro, Portugal)

The aim of this study was to investigate the levels and the spatial distribution of total Hg concentrations in soils from the urban area of Aveiro (Portugal) in order to assess the impact of industrial activities and identified Hg emission sources in these urban soils. For this purpose, soils were collected in 25 sampling points (at two depths) within the urban perimeter and in places considered representative of the main green areas of the city. A median concentration of 0.091 mg kg(-1) (dry weight) was obtained, regardless the depth. Aveiro was considered a low polluted city in terms of total Hg and no direct effects of emissions of Hg from industrial activities nearby could be detected in these urban soils. Despite of the low values obtained, high variability (range of approximately 0.5 mg kg(-1)) was observed in the results. Such was considered to be related to characteristic features of soils in urban settings and to the behaviour of Hg in the urban environment.     

Lake sedimentary evidence of phosphorus,iron and manganese mobilisation from intensively fertilised soils

A study of historical P inputs to Friary Lough, Co. Tyrone, Northern Ireland used a multi-sediment core approach. One of the sediment cores taken from the littoral zone at 2.5m water depth showed exceptionally high P, Fe and Mn concentrations below 20 cm sediment depth. Concentrations increased to 14 mg Pg(-1), 238 mg Feg(-1) and 35 mg Mng(-1) in the sediment profile and compared with deep basin maxima of 7 mg Pg(-1), 70 mg Feg(-1) and 2 mg Mng(-1) in surface sediments at 8.5m water depth. It is proposed that the high concentrations in the littoral zone core are due to post-depositional intrusion of chemical-rich local groundwater from soils in adjacent fields that are excessively fertilised with organic slurry. Soil analyses showed Olsen-P concentrations in these fields up to 125 mgkg(-1) at the soil surface (0-7.5 cm) and 39 mgkg(-1) in the sub-soil at 20 cm depth. We suggest that the mobilisation of P, Fe and Mn is due to leaching following P saturation and/or the loss of P absorbing chemicals due to prolonged reduction and complexing in wet soils. Further work will explore this relationship and the nature of the hydrological pathways through soil.     

Experimental investigations of blast-induced consolidation of loess soils

A method of consolidating loess soils by the detonation of horizontal explosive charges situated in two tiers at a distance of 3–4 m with respect to depth is proposed. Test results for a different alternation of the detonation of horizontal charges in the upper and lower tiers are cited. The saving generated by the method adopted is indicated. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 9–13, November–December, 1994.     

Experimental studies on curling development of artificial soils

Soil curling is an important phenomenon associated with volume changes induced by increasing soil suction upon desiccation. The study of soil behaviors associated with drying in soils (e.g. soil shrinkage, desiccation cracks and curling) has received increasing attention over the last few years, which has been mainly driven by the forecast climate change that will warm up our planet. There are significant gaps in the current knowledge related to the factors that control the development of curling deformations in soils. For this, the curling phenomenon is investigated through laboratory desiccation tests on different mixtures of artificial soils. The effects of soil grain size distribution, mineralogy, soil microstructure, and soil water content on the curling deformation are analyzed. Digital photos were taken at regular time intervals during the tests to understand the volume changes in the soil samples during drying. It is found that soil fabric and soil water content have significant effects on curling scenario. It is observed that the percentage of sand particles and the initial water content play a critical role in the development of soil curling. Samples of pure clayey minerals experienced shrinkage without or with minor curling during drying.     

Experimental assessment of an innovative process for simultaneous PAHs and Pb removal from polluted soils

This paper tests a soil washing process using flotation in its effectiveness for the removal of both polycyclic aromatic hydrocarbons (PAHs) and Pb from three polluted soils (soils A, B and C). The optimal flotation conditions were defined as: pulp density = 10%, Cocamidopropylhydroxysultaine (CAS) = 0.2% ww^− 1, [NaCl] = 5.5 M, pH = 3, flotation time = 15 min, air flow rate = 3 l min^− 1, stirring speed = 1800 rpm and temperature = 20 °C. Under these conditions, successive flotation stages (n), decreased the contaminant content to below permitted levels (up to 90% PAHs and Pb removal). Thus, a more contaminated matrix required the addition of a growing number of successive flotation stages to lower contamination levels below legal thresholds. While PAHs were distributed within the solid fractions of the process, Pb was mainly present in the liquid fractions. Electrodeposition allowed a total recovery of Pb after 60 min using a 2A electrical current.     

矿物掺合料抗氯离子扩散性能的试验研究

按照德国Aachen工业大学建筑材料研究所（ibac）采用的氯离子电迁移快速试验方法（RCM）测定混凝土中氯离子非稳定态快速迁移的扩散系数.试验结果表明：氯离子的扩散系数随粉煤灰、硅灰和高炉矿渣的掺量增加而降低,同时氯离子的扩散系数还与掺合料的种类有关,抗氯离子渗透能力依次为SF＞SG＞FA.分析并研究了粉煤灰、硅灰和高炉矿渣对混凝土抗氯离子渗透性能的影响.     

Experimental studies of the long-term deformability of clayey soils

Conclusions 1. Standard methods of determining the strain characteristics of a soil, e.g., GOST 12374-66, do not make it possible to evaluate to the fullest extent their yielding properties, which are governed by the rheological character of the deformation.2. The strain characteristics of soils (overall-compression modulus, stiffness coefficients of the foundation bed), which are determined from soil tests conducted in accordance with GOST 12374-66 may exceed their limiting long-term values obtained with consideration given to rheological properties by several factors (in our case, by a factor of 3.4).The use of stiffness coefficients on the high side for the design of buildings raised on nonuniformly deformable foundation beds (underexcavated sites, soils prone to slump-type settlement) leads to overdesigned structures. For these cases, therefore, it is recommended that the rheological characteristics of the soils be determined experimentally.3. For comparability of the rheological characteristics of soils determined from plate tests and on small specimens, it is necessary to assign consistent criteria for displacement stabilization, e.g., criteria that are interrelated over the depth of an equivalent layer.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 30–33, January–February, 1978.     

Experimental investigation of behavior of pile clusters in permafrost soils

Conclusions 1. The cluster effect depends on the state of the frozen soil; for hard-frozen soil it is manifested for a distance L2d between the piles, and for a plastic-frozen soil, for L 4d.2. For plastic-frozen soils account must be taken of the nonlinear creep settlement of the pile cluster, which is larger than the settlement of a single pile. The relation among the settlement, the number of piles in the cluster, and the distance between the piles has been established, and the corresponding method of analysis has been proposed.3. The load on the piles in the cluster is nonuniformly distributed, depending on the cap rigidity, the number of piles, the distance between them, and the state of the frozen soil. As a rule, the most loaded piles are those located farthest from the cap center, and the least loaded are those located inside the cluster.4. By applying the method of analysis of rigid plates on elastic bases of M. I. Gorbunov-Posadov, it is possible to analytically determine the loads on the piles in the cluster.Moscow Civil-Engineering Institute (MISI). Zabaikalpromstroniiproekt YaNIF Institute. Translated from Osnovaniya, Fundamenty i Mekhanika, Gruntov, No. 2, pp. 8–11, March–April, 1988.     

建筑墙体材料湿扩散率的测量

建筑墙体材料的湿扩散率表示水蒸气在该材料中的迁移能力,是研究墙体材料湿迁移所必需但相当匮乏的重要参数.在比较分析国内外有关湿迁移试验研究的基础上,设计了利用脉冲电导法获取建筑材料等温湿扩散率的试验方案,并对南京市普遍使用的多孔砖的湿扩散率进行了测试.     

Experimental checking of stability of underground pedestrian crossings on heaving soils

Conclusions 1. Underground crossing structures on natural soil bases may be used also for heaving soils provided their strength and rigidity are increased, taking into account the nonuniform deformations. It is recommended that a value of 0.0015 be used for the limiting allowable coefficient of relative deformation nonuniformity of tunnels.2. If the tunnel is considered as a reinforced concrete underground frame buried in the soil, then for strength, crack-resistance, and deflection design under the normal frost heave force, this force should be assumed to be equal to the soil reaction in the tunnel base under all the permanent and short-duration loads, taken in accordance with SNiP II-D.7-62; also, account must be taken of the friction force caused by the backfill sand on the tunnel lateral surface.3. For freezing and thawing of the soils in the bases of underground crossings, the plastic deformations are insignificant, i.e., the frost heave is practically equal to the settlement under thawing.4. The weak correlation between the coefficient K_n and the heave indicates that measures intended to reduce the depth of freezing (heave) by heating the bottom or by partially replacing the heaving soils by nonheaving under deep seasonal freezing cannot, per se, ensure crack resistance of the crossing structures.5. During freezing of soils in the bases of crossings, processes of heaving and shrink-age occur. For hard and medium hard consistency, with W_PL, the shrinkage may be greater than the heaving, which should be taken into account for determining the depth of the foundations under deep seasonal freezing conditions.Omskgrazhdanproekt. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 10–12, May–June, 1981.     

加筋土结构中加筋与土之间的摩擦性质研究

利用拉拔试验,对不同加筋材料,不同填料的加筋土的摩擦特性、抗拔位移的变化规律进行了研究,为今后的筋材拉拔试验及工程应用提供了参考.     

改性聚丙烯纤维混凝土氯离子扩散试验研究

聚丙烯纤维通过提高混凝土的早期抗裂能力增强了混凝土的抗渗性能。将掺入改性聚丙烯纤维的混凝土试件浸泡于3.5%NaCl溶液和青岛海域海水溶液中,测试混凝土不同深度的氯离子浓度,并计算不同腐蚀龄期混凝土的氯离子扩散系数,通过对比分析,研究掺入改性聚丙烯粗纤维或粗细混杂纤维后的混凝土的抗氯离子腐蚀性能。研究结果表明,掺加改性聚丙烯纤维能提高混凝土抗氯离子腐蚀性能,降低氯离子在混凝土中的扩散速率,且掺粗、细混杂纤维的效果要好于单掺纤维。