Active Weathering Research Articles

AVALIAÇÃO DA DISSIPAÇÃO NO AMBIENTE DO RATICIDA BRODIFACUM FORMULADO COMO BLOCO PARAFINADO

Para o controle químico de roedores na cidade de São Paulo, principalmente ratazanas, são colocados blocos parafinados contendo o ingrediente ativo (i.a.) brodifacum em bueiros sujeitos à ação das intempéries que podem acarretar alterações no i.a. e sua transferência para outros ambientes. Visando verificar essa possibilidade foram montados sistemas experimentais com blocos parafinados, simulando as condições de campo. Também foram colocados 100 blocos em bueiros monitorados semanalmente. Três blocos dos sistemas e dos bueiros foram coletados semanalmente, durante 10 semanas, e analisados por cromatografia a líquido de alta eficiência. Os dados obtidos foram utilizados para a avaliação da dissipação do i.a. Os resultados evidenciaram a estabilidade da molécula sob condições ambientais reais de aplicação, pois 100% do i.a. foram recuperados após a exposição do bloco. Já, nos sistemas experimentais, cerca de 50% dos blocos se soltaram do arame de fixação até a quinta semana de exposição e a recuperação do i.a. diminuiu gradativamente ao longo das 10 semanas de estudo, chegando a 50% da concentração inicial.

The long-term performance of two fly ash stabilized fine-grained soil subbases

An experimental study was conducted to investigate the long-term performance of fly ash stabilized two fine-grained soil subbases. One low plasticity clay soil and one high plasticity expansive clay soil were stabilized with a Class C fly ash with fly ash contents of 0%, 5%, 10%, and 20%, and compacted statically at the maximum dry density (standard Proctor) and at the optimum moisture content of the corresponding soil to prepare ten sets of replicates from each of the combinations. After curing all specimens for 7 days, the first set was subjected to plasticity index tests, unconfined compression tests, and vertical swell tests to estimate the improvement due to stabilization. Similar tests were also conducted on another nine sets of replicates in which six sets were subjected to 12 wet–dry cycles (three sets with tap water and the other three sets with saline water), and the other three sets were subjected to 12 freeze–thaw cycles in a laboratory controlled environment to simulate the weathering action. The effect of wet–dry cycles on stabilized soils was essentially insignificant; however, the fly ash stabilized soils lost up to 40% of the strength due to freeze–thaw cycles. Even after losing the strength significantly, the strength of stabilized soils was at least three times higher than that of the unstabilized soils. The swell potential of stabilized expansive soils also increased due to freeze–thaw cycles. The vertical swell increases rapidly for first four to five cycles and then increases very slowly.

Sedimentary environment of Ediacaran glacigenic diamictite in Guozigou of Xinjiang, China

The Talisayi Formation found in the Guozigou region on the southern side of Sayram Lake of Xinjiang, China is a Neoproterozoic glacigenic diamictite succession that has not been adequately researched. According to its isotopic geochronology and regional stratigraphic correlation, the Talisayi Formation is equivalent to the Ediacaran glacial sediments. The present paper provides the geochemical data of the Talisayi Formation that reveals the tectonic setting and sedimentary environment in this area during the Ediacaran period. The oxides of Si, K, Na and Al and their ratios of matrix materials from glacigenic diamictites and bulk rock of siltstone and argillaceous siltstones indicate that the sedimentary environment of this formation evolved from a tectonically active region to a passive continental margin. Values of CIA (carbonate-corrected Chemical Index of Alteration) ranging from 54 to 74 show a low-middle weathering action under a glacial environment. Total organic carbon (TOC), V/Cr, Ni/Co and U/Th ratios suggest that the sediments deposited in shallow water with an oxic and weak hydrodynamic condition. There is an abrupt rise in TOC, V/Cr, Ni/Co and U/Th ratios respectively in the overlying Lower Cambrian dolomitic limestones and in the bottom of Talisayi Formation, indicating a rapidl increase in biologic productivity and a variation in redox conditions, which was probably caused by seawater mixing of deep anoxic water and surface oxic water.

COMPORTAMENTO AMBIENTAL DO RATICIDA CUMATETRALILA EM PÓ DE CONTATO

No controle químico de roedores na cidade de São Paulo é aplicado cumatetralila em pó de contato na entrada das tocas, ficando sujeito a ação das intempéries, podendo acarretar alterações no ingrediente ativo (i.a.) e transferência para outros ambientes. Para verificar essas possibilidades, o raticida foi aplicado em sistemas experimentais simulando as condições de campo. Amostras de solo e água foram coletadas semanalmente, durante 10 semanas, e analisadas por cromatografia a líquido de alta eficiência. Os dados obtidos foram utilizados para a avaliação da dissipação do i.a. e seu potencial de lixiviação no perfil do solo. Os resultados apontaram a presença de cumatetralila na camada de 0 a 5 cm do solo durante as 10 semanas. Detectou-se cerca de 75% do i.a. aplicado nas 3 primeiras semanas, em torno de 20% entre a 5a e a 8ª semanas e cerca de 7% na 10ª semana. Nas amostras de água não foi detectado o i.a. durante as 10 semanas. Concluiu-se que o i.a. permanece no ambiente por pelo menos 10 semanas, sem atingir a água subterrânea considerando o tipo de solo utilizado.

Utilização de massas cerâmicas na produção de agregado sintético de argila calcinada para uso em concreto

A região amazônica, pela sua formação geológica, não dispõe de rochas de fácil acesso para uso na construção civil; devido a isto, o seixo rolado é obtido da dragagem do leito dos rios, sendo o agregado graúdo comercialmente mais utilizado para a produção de concreto. Neste trabalho é apresentado um estudo das características e propriedades tecnológicas de duas massas cerâmicas utilizadas para produção de tijolo, oriundas das cidades de Iranduba e Manacapuru, AM, com a finalidade de se fabricar agregado sintético de argila calcinada para uso em concreto. As massas cerâmicas foram submetidas a ensaios de difração de raios X, determinação de composição química e de distribuição do tamanho das partículas, e plasticidade. Foram confeccionados corpos-de-prova por prensagem uniaxial a 20 MPa para a queima nas temperaturas de 850, 950, 1050, 1150 ºC, sendo as propriedades tecnológicas após queima avaliadas por retração linear, absorção de água, massa específica aparente, massa unitária e temperatura de gresificação. A massa cerâmica que apresentou menor massa específica aparente e o menor percentual de umidade de moldagem foi escolhida como matéria-prima para a fabricação do agregado sintético de argila calcinada. Esse agregado foi usado em substituição ao agregado natural da região amazônica, o seixo rolado, em concreto estrutural.

Tar-Sands Drilling-Waste Management: A Clean Solution

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 112368, "Tar Sands Drilling Waste Management: A Clean Solution," by C. Nilsen, SPE, K. McCosh, SPE, and M. Kapila, SPE, M-I SWACO, originally prepared for the 2008 IADC/SPE Drilling Conference, Orlando, Florida, 4-6 March. The paper has not been peer reviewed. The full-length paper presents novel technology for treatment of tar-sands drilling waste generated from steam-assisted gravity drainage (SAGD) and other tar-sands drilling operations. The continuous treatment process is based on hot-water addition, mixing, and separation techniques to reduce the viscosity and specific gravity of the bitumen to separate it from the sand. Treatment of cuttings with light to heavy bitumen contamination has shown this treatment method to be a simple and effective means of producing clean sand and recovering the bitumen component. Introduction Tar sands are sandstone formations saturated with bitumen or heavy oil. The sandstone is thought to remain water-wet in the formation and can be unconsolidated, with the sand grains held together mainly by the bitumen. Alternatively, the sandstone can be consolidated, with silica or carbonate cement holding the sand together and bitumen filling the remaining voids. The bitumen deposits were formed in the geological past from crude oil that migrated to the surface of the Earth. Weathering and chemical and biological processes resulted in loss of the light fractions, leaving behind the very-viscous, solid or semisolid heavy fractions. Typically, bitumen has a density greater than 960 kg/m3. Over the millennia, weather and geologic action covered the semisolid bitumen with layers of soil, and today, most bitumen and heavy-oil production comes from deposits buried more than 400 m below the surface of the Earth. Bitumen deposits are found in more than 70 countries worldwide, but 75% occur in Canada and Venezuela. In Canada, most of the oil sands are located in three major areas in northern Alberta, which hold at least 175 billion bbl of recoverable bitumen. Where the heavy oil is thin it can be pumped out of the sands with progressing-cavity pumps (PCPs). To increase recovery, cold heavy-oil production with sand also is used in which sand is encouraged to enter the well by aggressive perforation and swabbing strategies. Removal of the sand with the heavy oil increases the formation permeability, expands the high-permeability zone as sand is produced, and prevents plugging of the near-wellbore region by asphaltenes or fines.

Calibration of Raman Spectroscopy at 1064 nm for Beeswax Quantification

In the early sixties, coating with molten beeswax was considered a valuable method for preventing the erosive action of weather and/or salinity on the surface of granite sculptures and monuments. This technique had been traditionally employed by the Galician stoneworkers for partial repair of historical monuments. For this purpose, beeswax was applied to the Renaissance Frieze in the Cloister of the Cathedral of Santiago de Compostela in Galicia (Northwest Spain). The beeswax treatment was counterproductive. An intense grain disaggregation of the granite can be observed in the Frieze, owing to the crystallization of salts. As a consequence, the restoration of the Cloister presents many problems. This fact imposes the need for an exhaustive study of the wax-stone system and the demand for a nondestructive method to measure the beeswax thickness at the stone surface. The aim of this contribution is the evaluation of a laser-based method, namely Fourier transform Raman spectroscopy, for analyzing the wax presence in specific rocky material of the Frieze to be restored. To obtain a reliable quantitative calibration, we prepared beeswax films of five different thicknesses on aluminum plates (26.6-97.2 microm). Nylon was selected as external reference to obtain the Raman emission independently from the laser beam power. The ratios of the relative intensities of the Raman bands corresponding to beeswax and nylon were used for the construction of a calibration curve used for the quantitative analysis. The intensities at 2879 cm(-1), I(c2879), and 2880 cm(-1), I(n2880), for beeswax and nylon, respectively, in the Raman spectra of each material were used. A linear dependence was found for the ratio I(c2879)/I(n2880) with the beeswax thickness. The validation of this calibration curve was tested with a second validation set of samples that spans beeswax film thicknesses both inside and outside the calibration range (12.1 to 180 mum), in order to evaluate in addition the accuracy of the model at extrapolation. Without complex sample preparation, near-infrared Raman spectroscopy resulted in an effective technique for localizing the wax with lateral resolution of tens of micrometers, and for determining wax layer thickness in the stone with an uncertainty of a few micrometers.

Interactions of sterile-cultured lichen-forming ascomycetes with asbestos fibres

Sterile cultured isolates of lichen-forming ascomycetes have not yet been used to investigate mycobiont–mineral substrate interactions under controlled conditions. In this study Candelariella vitellina, Xanthoparmelia tinctina and Lecanora rupicola mycobionts were isolated and inoculated with chrysotile fibres in the laboratory, in order to verify whether physical and chemical weathering processes, which were already described in the field, may be reproduced in vitro. Tight adhesion of hyphae to chrysotile fibres was observed in all species. The adhering hyphae affected the chemical composition of asbestos fibres, with the selective depletion of magnesium being a prominent feature, as is the case in field conditions. Oxalic acid and pulvinic acid, mycobiont-derived metabolites of X. tinctina and C. vitellina, were involved in the weathering action. Time and environmental factors and the absence of biological synergisms strongly limited the chemical weathering in vitro compared with what was observed in the field. Nevertheless, the results show that in vitro incubation of sterile-cultured lichen-forming fungi with minerals is a practicable experimental system to investigate the weathering effects of different mycobionts and fungal compounds under controlled conditions.

Safety assessment and protection of monuments located in caves - a case study from the city of Volos, Greece

The holy shrine ofPanagia (Saint Maria) Goritsis is located in a cave on the outer limits of the city of Volos, on the coastline. The stability problems caused by the loosening of the rockmass and the expansion of the joints generated issues about the safety of the numerous worshippers visiting the church every day. The cave is located into the Middle Triassic - Upper Jurassic marbles of the Pelagonian zone. The fragmentation of the rockmass along the two faults intersecting the slope until the coastline, combined with the weathering action of waves led to the formation of the cave. Although the action of the waves was cut of by the construction of the narthex and the surrounding buildings, the stability problems of the cave are intensified by the dynamic loading of the roof. The ceiling of cave is located 1 to 3 metres under the national road and the railway line connecting Volos with Agia. The selection of the proper support measures was complicated. The limited space, the small depth and most of all the religious and the historical value of the cave led to the selection of light support measures combined with the imposition of restriction for the reduction of the dynamic and the static loading

ASPECTOS TÉCNICOS DA UTILIZAÇÃO DA CAREPA GERADA EM PROCESSOS SIDERÚRGICOS E TRATADA POR DESAGREGAÇÃO ULTRA-SÔNICA

The Brazilian ironmaking has a waste average generation of 700kg per ton of produced steel. Recuperation of metallic contents presented in these wastes came to be very important either concerned to the limits obliged by the environmental legislation or by the economical point of view, inasmuch as they replace raw-materials employed in process. Mill scale is a product from the oxidation of steel when it is submitted to the thermal gradient or just action of weather. One pilot plant was installed in the VMB’s ETE-III, where was produced the cleaned mill scale for testing on the own company. The technique of USD showed this material is of easy processing and that it enhances its aggregated value, replacing with efficiency the use of scrap in refining operations.

Historic Period Faunal Remains from Mustang Springs on the Southern High Plains of Texas

Excavations at Mustang Springs, Texas, a key freshwater source on the Southern High Plains, have produced archaeological components of various ages, dating back to Paleoindian times. This report details a Historic fauna from the site that contains both native wild (bison, coyote) and domesticated (cattle, horse, sheep) species. Radiocarbon dates on the fauna fall into three age groups: modern, 100 B.P, and 280 B.P The assemblage is resting on a stratigraphic unconformity and shows evidence of postdepositional fluvial re-working and animal trampling, but was buried rapidly enough that the bone otherwise displays little evidence of surface weathering or carnivore action. The assemblage appears to represent an autochthonous fauna that accumulated gradually around the edge of a water hole, primarily by means of natural attrition. However, human action in the form of domestic management of cattle and sheep, and perhaps bison hunting, is also evidenced. Whether these bison were among the last of the Southern Plains bison herd killed by commercial hide hunters—as is known to have occurred near this locality—cannot be determined from the available evidence.

SCAT SURVEYS OF PRINCE WILLIAM SOUND BEACHES – 1989 TO 2002

ABSTRACT A SCAT survey in 2002 documented conditions at 39 selected survey sites where EVOS oil persisted in 1992, at the time the Federal and State On-Scene Coordinators determined that further cleanup activities would provide no net environmental benefit. The 2002 field survey found isolated occurrences of residual EVOS surface oil (SO) in the form of weathered asphalt pavement at 15 of the 39 sites. SO, expressed as a continuous oil cover, was less 0.2% of the surface area surveyed. Seven of the 39 sites and 815 (68%) of the total 1182 pits contained no residual SSO. SSO was found primarily in middle to upper intertidal locations, where it occurred in discontinuous ∼3cm thick bands 5–10 cm below the boulder/cobble or pebble/gravel veneer. Despite evidence of continued oil weathering, both at the surface and in the subsurface, it is clear that the natural cleaning processes at these particular locations are slow. The continued but slow weathering rates are a consequence of the oil being sequestered from the environment because it occurs in mixed (coarse and fine) sediments on beaches where boulders and outcrops, shallow bedrock asperities, or boulder-armoring limit effective physical weathering action.

Introduction to Weathering and Slope Movement papers

Weathering includes all the processes of chemicalalteration and physical breakdown of rock masses at, or near, the Earth's surface. Intense and/or continuous weathering processes may result in thick sequences of complex and heterogenous materials characterized by physical and geotechnical properties which have been strongly altered by the action of weathering. As a consequence, they may be prone to slope failures,erosion and landslides. In addition, availability of large amounts of weathered materials and loose debris in catchment basins may represent a serious hazard during, or following, intense rainfall, contributing significantly to the transport of sediment and debris during floods. Landslides in weathered materials occur in many different geological, morphological and environmental settings: shallow and rapid landslides (mostly soil slips evolving into debris flows) are among the most common type of slope movements, although large, deep-seated landslides also …

Fabric control on strain and rupture of heterogeneous shale samples by using a non-conventional mechanical test

This work was a part of the preliminary stage of the ANDRA project on a deep-seated research laboratory for the feasibility study of long-term radioactive waste storage in the Callovo–Oxfordian argillites of the Eastern part of the Paris Basin. These rocks are bedded, their density is about 2.4, and they contain an average of 30% carbonates and 25% quartz. Thick (5 mm) sections from cores were put through a non-conventional device called CGI testcell (CGI: Centre de Géologie de l'Ingénieur, i.e. Engineering Geology Centre). The aim of this versatile device is to achieve plane deformation tests under compressive uniaxial loading together with controlled temperature and humidity conditions, and to make, simultaneously, visual inspection of the sample's fabric. We also used X-ray diffractometry, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Our methodology was applied to samples from two horizons with contrasted lithology: one from near the roof of the formation (445 m deep), occurring in a black shale and nodular micritic limestone unit, and the other from the middle of the formation (480 m deep), occurring in a silty calcareous shale unit with abundant pyritic burrows. These tests have shown the major role of texture, structure and iron sulphides content in the deformation and the rupture of these argillites. The thick slides are brittle and in the conditions of the test, the finite axial strain before the rupture is less than 1%. The clay content controls the deformability. The bedding is responsible for weakness surfaces in the sample. The strength of the carbonate and pyrite aggregates is higher than that of the matrix, and these heterogeneities in the texture control the opening of fissures. Two types of cracks are distinguished: tension fractures parallel to the direction of the compression and oblique shear fractures, guided by the bedding. The principal mechanism at work for the evolution of the sample's texture is the weathering of pyrite glomerocrysts, which results in limonite and gypsum neogenesis. This in turn induces swelling and increasing porosity. The coupled action of weathering and mechanical stress leads to the rupture. In order to take into consideration the respective contribution of mechanical stress and weathering, we used numerical modelling with a finite difference code. We were then able to: (1) reproduce the essential observations on the deformation of a thick section of argillite modelled with a softening elasto-plastic behaviour; (2) quantify the influence of a local heterogeneity; and (3) explain the differences between the real test and the numerical test by the role of the rock structure and texture during its deformation. The image given by the studied samples is representative of the horizons from which they were extracted: the content in pyrite is 1–2% in the Callovo–Oxfordian argillite layer of interest. Consequently, we are brought to consider that, in the purpose of evaluating the area of the possibly damaged zones around a gallery, one should not only take into account the damage from mechanical origin and the damage due to drying effects. Indeed, our results lead us to regard the weathering of pyrite as a supplementary cause of damage that will develop around the facility along with time.

Sedimentation and pedogenic features in a clay deposit in Quadrilátero Ferrífero, Minas Gerais, Brazil

The clay deposit of Caxambu Hill occurs in a NW/SE oriented graben originated by syntectonic sedimentation during Cenozoic. Four facies were identified (fragmentary, nodular, massive and friable) and their differentiation is related to gravity mass-flow processes. The fragmentary facies is composed of extraclast fragments of the local Paleoproterozoic basement and sand size quartz-grains dispersed in a kaolinite-muscovite-goethitehematite matrix. The nodular facies is constituted by lithorelictal and pedorelictal nodules dispersed in a similar matrix as in the fragmentary facies. The massive facies is characterized by quartz grains dispersed in a kaolinite, hematite and goethite matrix with minor amounts of muscovite. The friable facies differs from the massive facies by its channel morphology, higher quartz and kaolinite content and the presence of millimetric clay-balls. The fragmentary facies is considered as deposited during the early stage of opening of the basin. After that, under sub-arid conditions, the slumping of lateritic materials from the surrounding regolith led to the formation of the nodular and massive facies. The friable facies was originated by the action of unidirectional flow that reworking the clayey sediments. The increasing of kaolinite content towards the top is related to the chemical weathering action after the deposition of the sediments.

Understanding feedback between ecological systems requires feedback among scientists

On a global scale, ecologists have long recognized the importance of feedback between aboveground and belowground ecological systems. In our general ecology classes, we teach that major world biomes are characterized by distinctive vegetation types, which are influenced both by climate and soil types. Soils, in turn, are a product of the mineral composition of the bedrock, the particular soil weathering action caused by that climate, and the physical and chemical characteristics of the organic matter returned to the soil by the vegetation. Soils and vegetation, students learn, are inextricably connected with each defining the identity of the other. In Communities and Ecosystems, Linking the Aboveground and Belowground Components,David Wardle examines how aboveground biological communities and ecosystems are linked to those in the soil at spatial scales smaller than a biome. He articulates his primary goal as considering terrestrial communities and ecosystems from a combined aboveground‐ belowground perspective in order to identify feedback between the two systems and to interpret how such feedback influences ecosystem functions such as carbon and nitrogen cycling. Wardle convincingly argues that understanding the linkages is important for predicting how changes in the components, including those caused by anthropogenic activity, affect ecosystem

Caracterização isotópica de metabasitos e anfibolitos dos Grupos Açungui e Setuva na Porção Sul da Faixa Ribeira

Pb, Rb, Sr, Sm and Nd isotope analyses were carried out on amphibolitic rocks from Campo Largo (PR), Rio Branco do Sul (PR) and Adrianópolis (PR) and for the metabasite from Adrianópolis and Apiaí (SP), all belonging to the Açungui and Setuva Groups, southern portion of the Ribeira Belt. These occurrences were chosen because each exhibits geochemical data indicative of a mantle source, having different signatures. Geochronologic determinations are available only for the Apiaí metagabbro with Neoproterozoic ages of 617 ± 4 Ma (U/Pb in zircon) and 839 ± 85 Ma (Rb/Sr, whole rock). Age determinations by Sm/Nd mineral isochron using whole rock, plagioclase and pyroxene yield values of 885 ± 53 Ma for the Apiaí metagabbro and 820 ± 84 Ma for the Adrianópolis metabasite. These results agree within error with the Rb/Sr isochron of 839 ± 85 Ma may possibly be interpreted as the time of extraction of the magma from the mantle, as suggested by positive µNd(850) values (+2,76) from an Adrianópolis sample. An µNd values versus 87Sr/86Sr diagram shows that each studied occurrence plots in a different position, following approximately the mantle array trend, the most primitive being the metabasite of Adrianópolis, near the MORB field, and the most enriched being the amphibolite from the same region, near the enriched mantle and or crustal contamination field. The distinct difference in isotopic signatures between the amphibolite and metabasite suggests derivation from different mantle sources, as supported by available geochemical data. Nevertheless, some of the samples show isotopic evidence of the action of metamorphism, crustal contamination and weathering.

Modeling of structural performances under coupled environmental and weather actions

The authors propose a so-called life-span simulator that can predict concrete structural behaviors under arbitrary external forces and environmental conditions. In order to realize this kind of technology, two computational systems have been developed; one is a thermohygro system that covers microscopic phenomena in C-S-H gel and capillary pores, and the other one is a structural analysis system, which deals with macroscopic stress and deformational field. In this paper, the unification of mechanics and thermo-dynamics of materials and structures has been made with the ion transport of chloride, CO2 and O2 dissolution. This proposed integrated system can be used for simultaneous overall evaluation of structural and material performances without distinguishing between structure and durability.

Modeling of structural performances under coupled environmental and weather actions

Modeling of structural performances under coupled environmental and weather actions

Rock-weathering by lichens in Antarctic: patterns and mechanisms

Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns, mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore, it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out in Antarctica.