Journal articles on the topic 'Reverse weathering'
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1
Misra, S., and P. N. Froelich. "Lithium Isotope History of Cenozoic Seawater: Changes in Silicate Weathering and Reverse Weathering." Science 335, no. 6070 (January 26, 2012): 818–23. http://dx.doi.org/10.1126/science.1214697.
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Mackenzie, F. T., and L. R. Kump. "Reverse Weathering, Clay Mineral Formation, and Oceanic Element Cycles." Science 270, no. 5236 (October 27, 1995): 586. http://dx.doi.org/10.1126/science.270.5236.586.
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Li, Fangbing, Donald Penman, Noah Planavsky, Andrew Knudsen, Mingyu Zhao, Xiangli Wang, Terry Isson, et al. "Reverse weathering may amplify post-Snowball atmospheric carbon dioxide levels." Precambrian Research 364 (September 2021): 106279. http://dx.doi.org/10.1016/j.precamres.2021.106279.
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Jeong, Gi Young, and Chang-Sik Cheong. "Recurrent events on a Quaternary fault recorded in the mineralogy and micromorphology of a weathering profile, Yangsan Fault System, Korea." Quaternary Research 64, no. 2 (July 18, 2005): 221–33. http://dx.doi.org/10.1016/j.yqres.2005.05.008.
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AbstractRecurrence characteristics of a Quaternary fault are generally investigated on the basis of field properties that are rapidly degraded by chemical weathering and erosion in warm humid climates. Here we show that in intense weathering environments, mineralogical and micromorphological investigations are valuable in paleoseismological reconstruction. A weathering profile developed in Late Quaternary marine terrace deposits along the southeastern coast of the Korean Peninsula was disturbed by tectonic movement that appears to be a simple one-time reverse faulting event based on field observations. A comparative analysis of the mineralogy, micromorphology, and chemistry of the weathering profile and fault gouge, however, reveals that both the microfissures in the deformed weathering profile and larger void spaces along the fault plane were filled with multi-stage accumulations of illuvial clay and silt minerals of detrital origin, suggesting a repetition of fissuring and subsequent sealing in the weathering profile as it underwent continuous mineralogical transformation and particle translocation. We reconstruct a sequence of multiple faulting events unrecognized in previous field surveys, which requires revision of the view that the Korean Peninsula was tectonically stable, during the Late Quaternary.
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Kasting, James F. "The Goldilocks Planet? How Silicate Weathering Maintains Earth “Just Right”." Elements 15, no. 4 (August 1, 2019): 235–40. http://dx.doi.org/10.2138/gselements.15.4.235.
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Earth's climate is buffered over long timescales by a negative feedback between atmospheric CO2 level and surface temperature. The rate of silicate weathering slows as the climate cools, causing CO2 to increase and warming the surface through the greenhouse effect. This buffering system has kept liquid water stable at Earth's surface, except perhaps during certain ‘Snowball Earth’ episodes at the beginning and end of the Proterozoic. A similar stabilizing feedback is predicted to occur on rocky planets orbiting other stars if they share analogous properties with Earth, most importantly an adequate (but not overly large) abundance of water and a mechanism for recycling carbonate rocks into CO2. Periodic oscillations between globally glaciated and ice-free climates may occur on planets with weak stellar insolation and/or slow volcanic outgassing rates. Most silicate weathering is thought to occur on the continents today, but seafloor weathering (and reverse weathering) may have been equally important earlier in Earth's history.
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Isson, Terry T., and Noah J. Planavsky. "Reverse weathering as a long-term stabilizer of marine pH and planetary climate." Nature 560, no. 7719 (August 2018): 471–75. http://dx.doi.org/10.1038/s41586-018-0408-4.
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Michalopoulos, P., and R. C. Aller. "Rapid Clay Mineral Formation in Amazon Delta Sediments: Reverse Weathering and Oceanic Elemental Cycles." Science 270, no. 5236 (October 27, 1995): 614–17. http://dx.doi.org/10.1126/science.270.5236.614.
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Du, Jianghui, Brian A. Haley, Alan C. Mix, April N. Abbott, James McManus, and Derek Vance. "Reactive-transport modeling of neodymium and its radiogenic isotope in deep-sea sediments: The roles of authigenesis, marine silicate weathering and reverse weathering." Earth and Planetary Science Letters 596 (October 2022): 117792. http://dx.doi.org/10.1016/j.epsl.2022.117792.
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Guo, Yong Jie, Ling Pan Du, Jin Zhong, Fu Yue Fang, and Ci Yun Chen. "Study on Separation of a Low Magnesium Semi-Weathered Phosphate Ore from Yunnan." Advanced Materials Research 962-965 (June 2014): 852–55. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.852.
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Weathered phosphate ore is an important part of phosphate ore resources, it contains a huge reserves of weathered phosphate ore resources in Yunnan regions. With the gradual consumption of the rich phosphate ore resources, recycling for weathering phosphate ore is receiving more and more people's attention. In this study, using a low magnesium semi-weathered phosphate ore which from Yunnan Dianchi Lake area as the research object, and based on its ore properties established a experimental program of pre- desliming with cyclone and then flotation. The loss rate of P2O5 under 20% on the desliming operation, then under the condition of ore grade of P2O5 is 21.23% using a positive-reverse flotation process, ultimately obtained a test indicators of phosphate concentrate of P2O5 grade of 28.41% and P2O5 recovery of 87.25%, which is a foundation of development and application of phosphate ore from Tian Ning semi-weathering ore.
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Bararzadeh Ledari, Masoomeh, Yadollah Saboohi, Antonio Valero, and Sara Azamian. "Exergy Analysis of a Bio-System: Soil–Plant Interaction." Entropy 23, no. 1 (December 23, 2020): 3. http://dx.doi.org/10.3390/e23010003.
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This paper explains a thorough exergy analysis of the most important reactions in soil–plant interactions. Soil, which is a prime mover of gases, metals, structural crystals, and electrolytes, constantly resembles an electric field of charge and discharge. The second law of thermodynamics reflects the deterioration of resources through the destruction of exergy. In this study, we developed a new method to assess the exergy of soil and plant formation processes. Depending on the types of soil, one may assess the efficiency and degradation of resources by incorporating or using biomass storage. According to the results of this study, during different processes from the mineralization process to nutrient uptake by the plant, about 62.5% of the input exergy will be destroyed because of the soil solution reactions. Most of the exergy destruction occurs in the biota–atmosphere subsystem, especially in the photosynthesis reaction, due to its low efficiency (about 15%). Humus and protonation reactions, with 14% and 13% exergy destruction, respectively, are the most exergy destroying reactions. Respiratory, weathering, and reverse weathering reactions account for the lowest percentage of exergy destruction and less than one percent of total exergy destruction in the soil system. The total exergy yield of the soil system is estimated at about 37.45%.
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Hu, Fei Nan, Chao Fu Wei, and Jing Du. "Comparison of Surface Electrochemical Properties between Purple Rocks and their Derived Soils as Related to Pedogenesis." Advanced Materials Research 476-478 (February 2012): 958–64. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.958.
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Soil surface electrochemical properties may have an important effect on soil fertility and genesis. Few researches are available on the changes of surface electrochemical properties of purple soils during the pedogenesis. In present work, four purple rocks and their derived soils under arable, orchard, forest and grass were collected to determine surface electrochemical properties including surface specific area, surface charge quantity, surface charge density, electric field strength, and surface potential using the kinetic method. The results indicated that soil surface specific area and surface charge quantity of soils were both significantly higher than their parent rocks. There were similar trends in surface potential, surface charge density and electric field strength of soils and parent rocks, soils derived from Shaximiao Formation (J2s) and Suining Formation (J3s) were higher than those of parent rocks, whereas the reverse trends existed in Feixianguan Formation (T1f) and Penglaizhen Formation (J3p). At the same time, surface potential of soil samples collected from four sites with different land utilization, i.e., Arable, Orchard, Forest and Grass, were determined to illustrate the various trends of soil electrochemical properties change. Under different land use patterns, the descending orders of soil surface potential in Shaximiao Formation (J2s) and Suining Formation (J3s) were both as follows: orchard > forest > arable > grass; the order in Feixianguan Formation (T1f) and Penglaizhen Formation (J3p) were as: orchard > forest > grass > arable. On the other hand, the value of soil surface charge quantity was increased with clay content and soil acidity because of the intensive physical weathering and slight chemical weathering. Therefore, the surface electrochemical properties may have some agreements with the weathering extent of the purple soils. Soil surface potential, surface charge quantity, surface charge density, electric field strength, and surface specific area could be employed as reference criteria for pedogenesis of purple soils.
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Hwang, Jong Yeon, Sunhwa Park, Moon-Su Kim, Hun-Je Jo, Gyong–Mi Lee, Sang Ho Jeon, Da Hee Song, et al. "Applications of Hydrochemical Models for Groundwater in Korea." Environment and Natural Resources Research 7, no. 3 (September 4, 2017): 51. http://dx.doi.org/10.5539/enrr.v7n3p51.
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The variation patterns of groundwater mobility and chemical distribution are regarded as a very important factor for determining the geochemical features and therefore, the classifications of groundwater based on the chemical properties are highly valued for the expansion of study areas for setting up the regulations and management plans of governmental level for the preservation of local groundwater. Based on these prerequisites, in this study we focused on the evaluations, the comparison of the physiochemical characteristics and distribution of cations and anions in groundwater samples sampled in rural areas of Korea. The major goals of this study were classified as four categories such as followings; 1. On-site monitoring of groundwater qualities by instrumental and laboratory experiment, 2. Classifications of groundwater by using of Piper, Gibbs and Chadah diagram methods, 3. Tracking of the origins of anions and cations by using of rock-dominance types and relative ionic distributions. As a result of this study, the classifications of groundwater based on the Piper diagram showed that the groundwater type is grouped as the Ca2+-(Cl--NO3-) and Ca2+-HCO3- type groups and these types are known as the general features of groundwater in Korea. And the tracking of dominance types (classified as evaporation, rock, precipitation) based on the Gibbs diagram have shown that the origins of anions and cations in groundwater are the rock-dominance. In the applications of CAI 1 and CA 2, the negative values were more dominance than positive values so there might be reverse ion reaction between groundwater and rock-soils. Finally, by the carbonate weathering, silicate weathering and evaporation diagrams there were more complex mechanisms in chemical evolutions induced by the lithological influences such as weathering processes, ion exchange and other anthropogenic sources.
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Stewart, E. M., Jay J. Ague, John M. Ferry, Craig M. Schiffries, Ren-Biao Tao, Terry T. Isson, and Noah J. Planavsky. "Carbonation and decarbonation reactions: Implications for planetary habitability." American Mineralogist 104, no. 10 (October 1, 2019): 1369–80. http://dx.doi.org/10.2138/am-2019-6884.
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Abstract The geologic carbon cycle plays a fundamental role in controlling Earth's climate and habitability. For billions of years, stabilizing feedbacks inherent in the cycle have maintained a surface environment that could sustain life. Carbonation/decarbonation reactions are the primary mechanisms for transferring carbon between the solid Earth and the ocean–atmosphere system. These processes can be broadly represented by the reaction: CaSiO3 (wollastonite) + CO2 (gas) ↔ CaCO3 (calcite) + SiO2 (quartz). This class of reactions is therefore critical to Earth's past and future habitability. Here, we summarize their significance as part of the Deep Carbon Obsevatory's “Earth in Five Reactions” project. In the forward direction, carbonation reactions like the one above describe silicate weathering and carbonate formation on Earth's surface. Recent work aims to resolve the balance between silicate weathering in terrestrial and marine settings both in the modern Earth system and through Earth's history. Rocks may also undergo carbonation reactions at high temperatures in the ultramafic mantle wedge of a subduction zone or during retrograde regional metamorphism. In the reverse direction, the reaction above represents various prograde metamorphic decarbonation processes that can occur in continental collisions, rift zones, subduction zones, and in aureoles around magmatic systems. We summarize the fluxes and uncertainties of major carbonation/decarbonation reactions and review the key feedback mechanisms that are likely to have stabilized atmospheric CO2 levels. Future work on planetary habitability and Earth's past and future climate will rely on an enhanced understanding of the long-term carbon cycle.
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Sun, Yong He, Lin Kang, Feng Xiang Yang, and Xue Song Li. "Analysis of Fault Characteristics and Reservoir Forming Control in Middle Fault Depression Belt in Hailer-Tamtsag Basin." Advanced Materials Research 616-618 (December 2012): 174–84. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.174.
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In order to reveal in middle fault depression belt of Hailer-Tamtsag Basin buried hill oil and gas migration and accumulation characteristics, we summarize controlling effect of fault on oil and gas migration and accumulation of buried hill, which by analysing genetic mechanism of buried hills based on fault systems formation and evolution. Research shows that three types of fault system in Hailer-Tamtsag Basin: early stretched fault system(Type I), early stretched middle tensile shearing fault system(Type I-II), early stretched middle tensile shearing reverse late fault system(Type I-II-III). Type I-II and I-II-III are stretching by NW tensional stress in Nantun group ,which afford tectonic framework for syngenesis buried hill and epigenetic buried hill. Type I make buried hills complicated .It is also favorable to ancient geomorphological buried hill in the fault less affected zones. Although they formed cracks dense zone easier, Type I-II and I-II-III fault system damage the reservoir which is not conducive to " hydrocarbon-supplying window " formation; Type I fault system have less promotion on the development of the buried hill reservoir, while it is conducive to hydrocarbon accumulation as the block boundary in buried hill hydrocarbon. Fault formed source rocks two kinds for hydrocarbon mode: unidirectional and bidirectional, which formed two reservoir-forming pattern: Unidirectional transportation hydrocarbon of weathering crust or hydrocarbon of fracture damage zones and bidirectional transportation hydrocarbon of weathering crust or hydrocarbon of fracture damage zones.
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Liu, Jinke, Guilin Han, Xiaolong Liu, Man Liu, Chao Song, Kunhua Yang, Xiaoqiang Li, and Qian Zhang. "Distributive Characteristics of Riverine Nutrients in the Mun River, Northeast Thailand: Implications for Anthropogenic Inputs." Water 11, no. 5 (May 7, 2019): 954. http://dx.doi.org/10.3390/w11050954.
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The nutrient contents of Mun River water in northeast Thailand during the dry season were measured to investigate the effect of human activities on dissolved load species. Dissolved organic carbon (DOC) values varied from 2.5 to 17.1 mg/L, averaging 9.0 mg/L; dissolved inorganic nitrogen (DIN) ranged between 0.12 and 0.11 mg/L; Cl− values ranged from 1.7 to 668.6 mg/L, with an average value of 84.8 mg/L; dissolved silicon (DSi) varied from 1.7 to 9.9 mg/L; and SO42− values averaged 8.9 mg/L. DOC, Cl−, and SO42− contents decreased with the flow direction. The high concentrations of DOC, K+, Cl−, and SO42− in the upper reaches were closely related to anthropogenic inputs, specifically industrial sewage. The covariation demonstrated that these dissolved loads may have the same sources. In other regions, Cl− contents were derived from weathering products. DIN contents maintained the same level on the river, and few sampling sites with high concentrations of DIN were influenced by point source pollution. The extremely low P concentrations limited algal growth, and the DSi showed no clear relationship with N and K, indicating that DSi in the Mun River was controlled by the weathering input rather than biological effects. The exact reverse spatial distributions of DOC between the wet and dry seasons (which increased with the flow direction in the wet season) were due to different precipitation rates, and the rare rainfall in the dry season had difficulty flushing the soil and transporting soil organic matter into the rivers. The local government should control sewage discharge and optimize farming methods.
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Krissansen-Totton, Joshua, and David C. Catling. "A coupled carbon-silicon cycle model over Earth history: Reverse weathering as a possible explanation of a warm mid-Proterozoic climate." Earth and Planetary Science Letters 537 (May 2020): 116181. http://dx.doi.org/10.1016/j.epsl.2020.116181.
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Sunuwar, S. C. "Geological mapping in the Nepal Himalaya: importance and challenges for underground structures." Journal of Nepal Geological Society 51 (December 31, 2016): 89–95. http://dx.doi.org/10.3126/jngs.v51i0.24096.
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Geological mapping is very important technique to predict geological condition for underground structures. It helps to construct geological model for site selection and designing of any underground structures. Geological uncertainty is directly proportional to the accuracy of geological mapping. More accurate geological mapping resulted fewer uncertainties. Precise delineation of faults, shear/weak zones and water bearing zones is important part of the geological mapping to predict uncertainties. Geological mapping to predict geological condition for underground structures is a challenge in the tectonically active Nepal Himalaya due to thrusting, faulting, folding and reverse metamorphism nature of rocks with difficult terrain and high overburden. The mapping for underground structures is mostly focus on rock mass properties, faults, weak/shear zones, fractured zone, joints, folds, weathering depth and ground water bearing zones. This paper highlights importance of geological mapping and challenges for underground structures with case studies of uncertainties faced due to poor geological mapping.
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Yu, Songtao, Yuxian Ke, Hongwei Deng, Guanglin Tian, and Junren Deng. "Experimental Investigation of Porous and Mechanical Characteristics of Single-Crack Rock-like Material under Freeze-Thaw Weathering." Minerals 11, no. 12 (November 26, 2021): 1318. http://dx.doi.org/10.3390/min11121318.
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Freeze-thaw weathering changes the pore structure, permeability, and groundwater transportation of rock material. Meanwhile, the change in rock material structure deduced by frost heaving deteriorates mechanical properties of rock material, leading to instability and insecurity of mine slopes in cold regions. In this paper, rock-like specimens containing prefabricated cracks at different angles and having undergone various freeze-thaw cycles are used as the object. Their pore structure, compressive mechanical properties, strain energies, failure characteristics, and the connection between pore structure and mechanical properties are analyzed. Results show that the porosity, spectrum area of mesopores, and spectrum area of macropores increase with the increase in freeze-thaw cycles, while crack angle shows no obvious influence on pore structure. Peak stress and elastic modulus drop with the increase in freeze-thaw cycles, while peak strain shows an increasing trend. Peak stress and elastic modulus decrease in the beginning, and then increase with the increase in crack angle, while peak strain shows a reverse trend. Elastic strain energy and pre-peak strain energy drop with the increase in freeze-thaw cycles. Elastic strain energy decreases first, and then increases with the increase in crack angle. The correlation between the spectrum area of macropores and elastic modulus is the strongest among different pores. Elastic modulus and peak stress decrease with the increase in macropore spectrum area, and peak strain increases with the increase in macropore spectrum area.
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Benaafi, Mohammed, and Abdulaziz Al-Shaibani. "Hydrochemical and Isotopic Investigation of the Groundwater from Wajid Aquifer in Wadi Al-Dawasir, Southern Saudi Arabia." Water 13, no. 13 (July 3, 2021): 1855. http://dx.doi.org/10.3390/w13131855.
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The Wajid aquifer is considered the main source of water for drinking and irrigation in Wadi Al-Dawasir and Najran, the southern region of Saudi Arabia. This aquifer has been used since the 1960s, and due to the expansion in agricultural activities, the aquifer has been overexploited. The study aims to understand the origin, hydrochemical processes of the groundwater in the shallow unconfined, deep unconfined, and confined parts of the Wajid aquifer in the Wadi Al-Dawasir area. In-situ hydrochemical parameters (pH, temperature, EC, and TDS) were measured in the field, and groundwater samples were collected for major ions and stable isotopes (2H and 18O) measurements in the laboratory. The results show that the groundwater in shallow unconfined, and confined aquifers are of two types; Cl.SO4-Ca. Na and Cl.SO4-Na. Ca; however, groundwater in deep, unconfined aquifers is characterized as HCO3-Ca. Na, and Cl. HCO3-Ca. Na; types of groundwater. The isotopic analysis results reveal that all groundwater samples have values of δ18Oand δ2Hclose to the local and global meteoric water lines, indicating the meteoric origin of Wajid groundwater. Three major hydrochemical processes, including rock weathering, ion exchange, and evaporation, have been identified as key controls on the chemical composition of water in the studied aquifer. The evaporation and ion exchange processes have more influence on the chemical composition of groundwater in the shallow unconfined and confined aquifers. On the contrary, weathering of carbonate minerals affected more the chemistry of groundwater in a deep unconfined aquifer. The unconfined section of the Wajid aquifer shows a reverse pattern of salinity with higher salinity in the recharge area, which is most probably related to the return irrigation water and leaching of salty soil. The open fractures in the upper part of Wajid sandstone most likely act as conduits to percolated saline water to the Wajid aquifer.
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Ullah, Zahid, Muhammad Afnan Talib, Abdur Rashid, Junaid Ghani, Asfandyar Shahab, Muhammad Irfan, Abdur Rauf, Sami Bawazeer, Zainab M. Almarhoon, and Yahia N. Mabkhot. "Hydrogeochemical Investigation of Elevated Arsenic Based on Entropy Modeling, in the Aquifers of District Sanghar, Sindh, Pakistan." Water 13, no. 23 (December 6, 2021): 3477. http://dx.doi.org/10.3390/w13233477.
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Arsenic (As) contamination in drinking groundwater is a common environmental problem in Pakistan. Therefore, sixty-one groundwater samples were collected from various groundwater sources in District Sanghar, Sindh province, Pakistan, to understand the geochemical behavior of elevated As in groundwater. Statistical summary showed the cations and anions abundance in decreasing order of Na+ > Ca2+ > Mg2+ > K+, and HCO3− > Cl− > SO42− > NO3−. Arsenic was found with low to high concentration levels ranging from 5 µg to 25 µg/L with a mean value of 12.9 µg/L. A major water type of groundwater samples was mixed with NaCl and CaHCO3 type, interpreting the hydrochemical behavior of rock–water interaction. Principal component analysis (PCA) showed the mixed anthropogenic and natural sources of contamination in the study area. Moreover, rock weathering and exchange of ions controlled the hydrochemistry. Chloro-alkaline indices revealed the dominance of the reverse ion exchange mechanism in the region. The entropy water quality index (EWQI) exposed that 17 samples represent poor water, and 11 samples are not suitable for drinking.
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Sazakli, Eleni, Stavroula V. Zouvelou, Ioannis Kalavrouziotis, and Michalis Leotsinidis. "Arsenic and antimony removal from drinking water by adsorption on granular ferric oxide." Water Science and Technology 71, no. 4 (November 17, 2014): 622–29. http://dx.doi.org/10.2166/wst.2014.460.
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Arsenic and antimony occur in drinking water due to natural weathering or anthropogenic activities. There has been growing concern about their impact on health. The aim of this study was to assess the efficiency of a granular ferric oxide adsorbent medium to remove arsenic and antimony from drinking water via rapid small-scale column tests (RSSCTs). Three different water matrices – deionized, raw water treated with a reverse osmosis domestic device and raw water – were spiked with arsenic and/or antimony to a concentration of 100 μg L−1. Both elements were successfully adsorbed onto the medium. The loadings until the guideline value was exceeded in the effluent were found to be 0.35–1.63 mg g−1 for arsenic and 0.12–2.11 mg g−1 for antimony, depending on the water matrix. Adsorption of one element was not substantially affected by the presence of the other. Aeration did not affect significantly the adsorption capacity. Granular ferric oxide could be employed for the simultaneous removal of arsenic and antimony from drinking water, whereas full-scale systems should be assessed via laboratory tests before their implementation.
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Neal, C., B. Reynolds, J. K. Adamson, P. A. Stevens, M. Neal, M. Harrow, and S. Hill. "Analysis of the impacts of major anion variations on surface water acidity particularly with regard to conifer harvesting: case studies from Wales and Northern England." Hydrology and Earth System Sciences 2, no. 2/3 (September 30, 1998): 303–22. http://dx.doi.org/10.5194/hess-2-303-1998.
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Abstract. Data on the water quality of streams draining a range of acidic and acid sensitive, mainly afforested, upland catchments in mid- and north-Wales and northern-England are described to investigate the acidification effects of conifer harvesting in relation to natural variability. Most sites show a large range in pH and major cation and major anion concentrations. The waters draining from the smaller catchments are more acidic and aluminium bearing reflecting a higher proportion of runoff from the acidic soils in each area. However, there is often a less acidic component of runoff under base-flow conditions due to ground-water contributions particularly within the larger streams. Higher concentrations of nitrate occur for sites which have been felled although declines in concentration occur several years after felling. Multiple regression analysis reveals the importance of cation exchange and within catchment acidification associated with sulphate and nitrate generation. Sulphate also has a component associated with weathering but the patterns vary from catchment to catchment. Analysis of the influence of changing anion concentrations associated with tree harvesting reveals that the acidification induced by increases in nitrate can be offset or reversed by the lowering of chloride and sulphate concentrations due to decreased atmospheric scavenging by the vegetation, reduced evapotranspiration and increased surface runoff diluting the acidity generated. It is concluded that contemporary UK forestry guidelines with an emphasis on phased harvesting of catchments over several years and careful harvesting methodologies can alleviate most problems of stream acidification associated with felling activities and in some cases can reverse the acidification pattern.
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Mottershead, Derek N., Philip J. Soar, Malcolm J. Bray, and Linley J. Hastewell. "Reconstructing Boulder Deposition Histories: Extreme Wave Signatures on a Complex Rocky Shoreline of Malta." Geosciences 10, no. 10 (October 6, 2020): 400. http://dx.doi.org/10.3390/geosciences10100400.
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The Żonqor coastline, southeast Malta, displays an exceptional range of geomorphic signatures of extreme coastal events. This paper brings together evidence acquired from a field survey, analysis of time-sequential imagery, and hydrodynamic modelling to investigate the histories of boulder groups identified by their intrinsic and contextual characteristics. Clear differences are revealed between the distribution of boulders recently moved and those of considerable age. Tracking the movement of boulders since 1957 confirms that storms of surprisingly frequent interval are capable of complex boulder movements, including lifting of megaclasts. Scrutiny of the ancient boulders, including weathering features and fascinating landward-facing (reverse) imbrication, cautiously suggests tsunami as the agent for their emplacement. A novel method is developed for depicting the velocity decay profiles of hypothetical waves, which overcomes some of the limitations of the Nott approach. Applied here, the wave run-up context further sets the ancient movers apart from their recent mover companions. The combined evidence implies a palimpsestic landscape where storm waves are regular geomorphic agents that add to and rework the distribution of boulders close to the shoreline, but over long time periods the landscape becomes reset by tsunami—a concept that is of value to agencies in Malta responsible for coastal safety, planning and management.
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Gomaa, Hassan E., AbdAllah A. Alotibi, Mohamed Charni, Abdulhadi H. AlMarri, and Fatma A. Gomaa. "Conceptual Evaluation of Factors Controlling Groundwater Chemistry in Ad-Dawadmi, Saudi Arabia, Using Visualization and Multiple Lines of Evidence." Water 14, no. 12 (June 9, 2022): 1857. http://dx.doi.org/10.3390/w14121857.
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Understanding the hydrogeochemical and physicochemical processes and factors controlling the chemical characteristics of groundwater (GW) is essential in water resources studies. In this work, the authors explored, applied, and evaluated the practicality of a series of analysis methods, exploring their ability to improve the representation of the generic GW chemical datasets. The demonstration resulted in a detailed explanation of findings and interpretations, which benefits newcomers who may not be experts in managing such data. Visualization-based, facile, readily readable, and interpretable graphs were tuned and applied to identify the interconnected controlling factors. The examined varieties were bubble diagrams, 3D surface plots, and scatter box plot matrices. Box plot matrices yielded intensive information about the significant interacting parameters in one graph. Employing bubble diagrams produced vast detail, allowing the identification of the significant processes and enabling the recognition of internally acting mechanisms that were otherwise hidden. The identified GW evolution processes include aerosol dissolution, evaporation, direct and reverse ion exchange, precipitation of calcium salts, flushing out of soil-bounded salts, and rock weathering. pH and HCO3− fluctuations coupled with evaporation were recognized as prominent factors giving rise to the vicious salinization cycle, which is thought to be the process causing the worst deterioration in the GW quality and the salinity within the study area.
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Bouderbala, Abdelkader. "Assessment of the seasonal variations in hydrochemistry of Oued Fodda dam, Algeria." Environmental & Socio-economic Studies 9, no. 3 (September 1, 2021): 78–90. http://dx.doi.org/10.2478/environ-2021-0019.
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Abstract This study was carried out on the surface water of Oued Fodda dam in western Algeria, and aimed to evaluate the seasonal variations of chemical characteristics with the aim to define the processes controlling the mineralization of surface water in this dam. The results showed significant variations in the majority of parameters during the study period from 2009 to 2013, indicating slightly alkaline water, and a SO4-Cl-Ca-Mg water type. Principal component analysis (PCA) and cluster analysis (CA) were used to explain the correlations between the parameters analysed, and the probable sources of surface water contamination. The calculation of saturation indices (SI) of water indicated undersaturated water with respect to halite (NaCl), and equilibrium with respect to the other minerals. While, the temporal variation of physico-chemical parameters such as EC, TDS, SO4 2-, Cl-, Ca2+, Mg2+ indicated a reverse adjustment between physico-chemical parameters and water volumes (WV) in this dam, which can be explained by the weathering of silicate and carbonate minerals, these were justified by the use of ionic ratios, diagrams and scatter plots and multivariate statistical techniques. Conversely, evaluation of the organic water pollution level in this dam showed a water quality from moderately to severely polluted.
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Ratri, D., D. P. E. Putra, and W. Wilopo. "Groundwater geochemistry and hydrogeochemical processes assessment in Bantul, Yogyakarta, Indonesia." IOP Conference Series: Earth and Environmental Science 958, no. 1 (December 1, 2021): 012013. http://dx.doi.org/10.1088/1755-1315/958/1/012013.
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Abstract In Bantul, Southern Yogyakarta, groundwater is the main source of domestic water needs. Therefore, knowing the hydrogeochemistry of groundwater is crucial in order to manage a sustainable groundwater resource. To characterize the compelling geochemical processes that control the groundwater chemistry, further hydrogeochemical examinations were directed in the area. Thirty groundwater samples were collected from shallow dug wells during the early dry season (April 2021). Sampling procedures and chemical analysis were carried out as per standard methods with secondary data obtained in 2006. The geochemical evaluations were depicted using several graphical plots dependent on the ionic constituents, hydrochemical facies, and controlling factors of groundwater quality. Two major hydrochemical facies were identified: alkaline-earth water with higher alkali; bicarbonate predominated (62%) and alkaline-earth water; bicarbonate predominated (32%). Weathering of silicate minerals occurs in 70% of recent samples and predominantly regulates major ion chemistry such as calcium, magnesium, sodium, and potassium. Chloro-alkaline indices 1,2 values signify that there are two potential rock-water interaction processes in the study region, namely the ion exchange and reverse ion exchange. Concentrations of nitrate, sulfate, and chloride indicate that the water chemistry has not been heavily contaminated by the land use in the area and is still mainly controlled by geogenic processes rather than anthropogenic activities.
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Santiago Ramos, Danielle P., Leah E. Morgan, Nicholas S. Lloyd, and John A. Higgins. "Reverse weathering in marine sediments and the geochemical cycle of potassium in seawater: Insights from the K isotopic composition (41K/39K) of deep-sea pore-fluids." Geochimica et Cosmochimica Acta 236 (September 2018): 99–120. http://dx.doi.org/10.1016/j.gca.2018.02.035.
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Academe, S. O., P. C. Emenike, P. Unokiwedi, C. C. Nnaji, and M. A. Etim. "Suitability and hydrogeochemical imprints of groundwater in residential location around Abeokuta, southwestern Nigeria." IOP Conference Series: Earth and Environmental Science 993, no. 1 (March 1, 2022): 012016. http://dx.doi.org/10.1088/1755-1315/993/1/012016.
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Abstract Water quality evaluations of domestic wells are required to monitor its consumption suitability since its dependence is on an increasing rate in the study region. Therefore, the rationale for the study is to obtain the hydrogeochemical characteristics of water from domestic wells and their level of potability. In the current study, the hydrogeochemical footprints of twenty water samples obtained from deep wells located in residential buildings were analyzed for TDS, Turbidity, TSS, TH, Acidity, Alka, HCO3 −, CO3 2-, DO, NO2 −, NO3 −, SiO2, PO4 3-, SO4 2-, Br−, Cl−, F−, Ca2+, Fe2+, Mg2+, K+, Na+, EC and ranked using the entropy-based water quality index (EBWQI) to determine its drinking suitability.Water classification was achieved using hydrogeochemical facies and the ion exchange was obtained using biplots of important water quality parameters. The mean concentration of the water quality parameters mentioned above were 717.69, 46.11, 157.20, 224.81, 72.91, 64.06, 78.07, 0.01, 3.89, 0.89, 51.56, 16.50, 0.73, 32.87, 0.01, 174.41, 1.89, 58.91, 0.03, 19.41, 3.05, 72.82 mg/L and 1009.63 μS/cm, respectively. Benchmarking the results with the WHO 2017 standard, 10%, 85%, 10%, 45%, 20%, and 45% of the water samples surpassed the threshold for TDS, EC, DO, NO3 −, Cl−, and F−, respectively. The groundwater classification derived from the piper plot revealed 40% mixed type, 15% Na-Ca-Cl water type, 15% Na-Ca-Mg-Cl water type, 20% Ca-Na-Cl water type, and 10% Ca-Na-Mg-Cl water type, with Na and Cl dominating the hydrogeochemical facies. The geochemical activity governing the groundwater chemistry obtained from the plot of [Ca2+ + Mg2+] vs [HCO3 − + SO4 2−] showed silicate weathering and carbonate weathering in 5% and 95% of the water samples, respectively. Furthermore, the ion exchange activity based on [Na+ + K+ – Cl−] vs [(Ca2+ + Mg2+) – (HCO3 − + SO4 2–)], CAI-1 and CAI-2 plots supports reverse ion exchange. Generally, the chemical activities support rock-water and evaporation dominance within the sample location. The EBWQI ranking showed that 10% of the water samples are excellent, 20% are good, 40% are moderate, 10% are poor, and 20% of the water samples are abysmal for consumption. Therefore, the water situation in the study region requires adequate treatment strategies to foster healthy living for residents.
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Goodsell, Becky, Michael J. Hambrey, and Neil F. Glasser. "Formation of band ogives and associated structures at Bas Glacier d’Arolla, Valais, Switzerland." Journal of Glaciology 48, no. 161 (2002): 287–300. http://dx.doi.org/10.3189/172756502781831494.
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AbstractStructural glaciological, sedimentological and geophysical techniques are used to provide new insight concerning the formation of band ogives and associated structures at Bas Glacier d’Arolla, Switzerland. Sedimentary stratification, crevasse traces and transverse foliation are identified as planar structures in the lower icefall and glacier tongue. Stratification and crevasse traces are progressively deformed into, and enhance, the transverse foliation found in the glacier tongue. Three-dimensional geometry has been defined using ground-penetrating radar, which portrays four main characteristics: (i) deep reflectors interpreted as the ice/bed interface, (ii) alternating reflection-rich and reflection-poor zones interpreted as ogives, (iii) up-glacier-dipping reflectors, interpreted as planar structures, and (iv) down-glacier-dipping reflectors of uncertain origin. At the glacier surface, each band ogive consists of a light and dark band. The dark bands contain more intense foliation which, on differential weathering, traps fine debris. Clasts and clear ice of basal character within dark ogive bands suggest that basal ice has been raised to the glacier surface. The most applicable model for the formation of band ogives at Bas Glacier d’Arolla is a refinement of Posamentier’s (1978) “reverse faulting” hypothesis. In this context, multiple shear zones are formed, through which basal ice is uplifted to the glacier surface to produce the dark, foliated ogive bands. This model fits observations reported from other glaciers with band ogives.
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Adembri, B., L. Cipriani, and G. Bertacchi. "GUIDELINES FOR A DIGITAL REINTERPRETATION OF ARCHITECTURAL RESTORATION WORK: REALITY-BASED MODELS AND REVERSE MODELLING TECHNIQUES APPLIED TO THE ARCHITECTURAL DECORATION OF THE <i>TEATRO MARITTIMO, VILLA ADRIANA</i>." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-5/W1 (May 16, 2017): 599–606. http://dx.doi.org/10.5194/isprs-archives-xlii-5-w1-599-2017.
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The Maritime Theatre is one of the iconic buildings of Hadrian’s Villa, Tivoli. The state of conservation of the theatre is not only the result of weathering over time, but also due to restoration work carried out during the Fifties of the past century. Although this anastylosis process had the virtue of partially restoring a few of the fragments of the compound’s original image, it now reveals diverse inconsistencies and genuine errors in the reassembling of the fragments. This study aims at carrying out a digital reinterpretation of the restoration of the architectural fragments in relation to the architectural order, with particular reference to the miscellaneous decoration of the frieze of the <i>Teatro Marittimo</i> (vestibule and <i>atrium</i>). <br><br> Over the course of the last few years the <i>Teatro Marittimo</i> has been the target of numerous surveying campaigns using digital methodology (laser scanner and photogrammetry SfM/MVS). Starting with the study of the remains of the <i>opus caementicium</i> on the ground, it is possible to identify surfaces which are then used in the model for subsequent cross sections, so as to achieve the best fitting circumferences to use as reference points to put the fragments back into place.
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Ma, Jie, Song Chen, Songbao Feng, and Diandian Ding. "Hydrochemical characteristics, hydraulic connectivity and water quality assessment of multilayer aquifers in Western Suzhou City, Northern Anhui Province, China." Water Supply 22, no. 3 (December 22, 2021): 2644–58. http://dx.doi.org/10.2166/ws.2021.445.
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Abstract The present study focuses on the shallow phreatic aquifer (SA) and the upper confined aquifer (CA) developed in Cenozoic loose strata, which are the major regional groundwater resources for drinking, irrigation, industry and other water-related activities. Seven samples from SA and seventeen samples from CA were analyzed to depict the hydrochemical characteristics, categorize the hydrochemical facies, evaluate the hydraulic connectivity, and appraise the drinking water and irrigation water quality. The abundance of cations is Na+ > Ca2+ > Mg2+ > K+ and the anions is HCO3− > SO42− > Cl− in both aquifers, respectively. Groundwater chemistry is controlled by water-rock interactions such as halite dissolution, ion exchange, reverse ion exchange, silicate weathering, and followed by the dissolution of Glauber's salt. The low connectivity and moderate connectivity between these two aquifers has engendered. The majority of the ion concentrations are within the limit for drinking, only one sample from the shallow aquifer was greater than the limit of 250 mg/L, a total of 29% from the shallow unconfined aquifer and 14% from the confined aquifer are not within the limit of 250 mg/L. The sodium absorption ratio (SAR), residual sodium carbonate (RSC) and soluble sodium percentage (%Na) values reveal that all the samples are appropriate for irrigation uses. The the US salinity laboratory (USSL) diagram shows that sixteen CA samples and all the SA samples fall in the C3S1 zone, implying high salinity hazard and low alkalinity hazard.
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Sellmann, Schirin, Mark Quigley, Brendan Duffy, and Ian Moffat. "Ground Penetrating Radar of Neotectonic Folds and Faults in South-Central Australia: Evolution of the Shallow Geophysical Structure of Fault-Propagation Folds with Increasing Strain." Geosciences 12, no. 11 (October 26, 2022): 395. http://dx.doi.org/10.3390/geosciences12110395.
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Using ground penetrating radar (GPR) we investigate the near surface (~0–10 m depth) geophysical structure of neotectonic fault-propagation folds and thrust faults in south-central Australia in varying stages of fold and fault growth. Variations in neotectonic fold scarp heights are interpreted to reflect variations in accumulated slip on the underlying reverse faults. Fold scarps on the Nullarbor and Roe Plains are characterized by broad, asymmetric morphologies with vertical displacements of ~5 to ~40 m distributed over 1 to 2 km widths (~0.5 to ~4 m per 100 m). Within increasing scarp height there is an increase in the frequency and spatial density of strong reflector packages in the hanging wall that are attributed to material contrasts imposed by co-seismic fracturing and associated lithological and weathering variations. No evidence for discrete faulting is found at scarp heights up to 40 m (maximum relief of 4 m per 100 m). Where the principal slip zone of a fault ruptures to the surface, scarp morphologies are characterized by steep gradients (ca. 10 m per 100 m). Discrete faulting is imaged in GPR as structural lineaments, abrupt changes in the thickness of reflector packages with variations of amplitude, and/or hyperbolic diffraction packages indicative of the disturbance of reflector packages. Geophysical imaging of subtle changes in the shallow geological structure during growth of fault-propagation folds can be conducted using GPR informing the identification of locations for invasive investigations (e.g., trenching).
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MAEDA, Hiroyuki, Masanori KOHNO, Junpei KOTAKE, and Susumu ANDO. "Significance of weathering zone in a reverse-dip slope type landslide occurred on a diagenetic zone hard shale : an example of the Honki Slide area in northeastern Hokkaido, Japan." Journal of the Japan Landslide Society 51, no. 1 (2014): 13–20. http://dx.doi.org/10.3313/jls.51.13.
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Chegbeleh, Larry Pax, Bismark Awinbire Akurugu, and Sandow Mark Yidana. "Assessment of Groundwater Quality in the Talensi District, Northern Ghana." Scientific World Journal 2020 (April 10, 2020): 1–24. http://dx.doi.org/10.1155/2020/8450860.
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A comprehensive chemical quality assessment of groundwater resources in the Talensi District has been conducted using conventional graphical methods and multivariate statistical techniques. The study sought to determine the main controls of groundwater chemistry and its suitability for domestic and irrigation purposes in the district. Silicate and carbonate mineral weathering were identified as the main controls on groundwater chemistry in the district, with reverse ion exchange also playing a role. High nitrate and lead levels observed have been associated with agrochemicals and wastewater from farms and homes. Three main flow regimes have been identified with Q-mode cluster analysis, in which mixed cation water types have been revealed, where areas designated as recharge zones are dominated by Na+ + K+–Mg2+–HCO3− fresh water types characterised by low mineralisation and pH, which evolve into Mg2+– Na+ + K+– HCO3− fresh water type with corresponding increased mineralisation of the groundwater. Based on the water quality index (WQI) technique modified for the district and an interpolation technique using ordinary kriging developed from a well-fitted exponential semivariogram for the estimated WQIs, the groundwater quality has been spatially classified as generally ‘good’ to ‘excellent’ for domestic purposes. Generally, the quality of groundwater for domestic usage deteriorates as one moves towards the north of the district, whereas waters in the east and west present the best quality. Classifications based on the United States Salinity Laboratory (USSL), Wilcox, and Doneen diagrams suggest that groundwater from the unconfined aquifers of the district is of excellent quality for irrigation purposes.
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Yergeau, Etienne, Mélanie Arbour, Roland Brousseau, David Juck, John R. Lawrence, Luke Masson, Lyle G. Whyte, and Charles W. Greer. "Microarray and Real-Time PCR Analyses of the Responses of High-Arctic Soil Bacteria to Hydrocarbon Pollution and Bioremediation Treatments." Applied and Environmental Microbiology 75, no. 19 (August 14, 2009): 6258–67. http://dx.doi.org/10.1128/aem.01029-09.
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ABSTRACT High-Arctic soils have low nutrient availability, low moisture content, and very low temperatures and, as such, they pose a particular problem in terms of hydrocarbon bioremediation. An in-depth knowledge of the microbiology involved in this process is likely to be crucial to understand and optimize the factors most influencing bioremediation. Here, we compared two distinct large-scale field bioremediation experiments, located at the Canadian high-Arctic stations of Alert (ex situ approach) and Eureka (in situ approach). Bacterial community structure and function were assessed using microarrays targeting the 16S rRNA genes of bacteria found in cold environments and hydrocarbon degradation genes as well as quantitative reverse transcriptase PCR targeting key functional genes. The results indicated a large difference between sampling sites in terms of both soil microbiology and decontamination rates. A rapid reorganization of the bacterial community structure and functional potential as well as rapid increases in the expression of alkane monooxygenases and polyaromatic hydrocarbon-ring-hydroxylating dioxygenases were observed 1 month after the bioremediation treatment commenced in the Alert soils. In contrast, no clear changes in community structure were observed in Eureka soils, while key gene expression increased after a relatively long lag period (1 year). Such discrepancies are likely caused by differences in bioremediation treatments (i.e., ex situ versus in situ), weathering of the hydrocarbons, indigenous microbial communities, and environmental factors such as soil humidity and temperature. In addition, this study demonstrates the value of molecular tools for the monitoring of polar bacteria and their associated functions during bioremediation.
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Zhang, Mengnan, Shuangbao Han, Yushan Wang, Zhan Wang, Haixue Li, Xiaoyan Wang, Jiutan Liu, Changsuo Li, and Zongjun Gao. "Characteristics and Controlling Factors of Groundwater Hydrochemistry in Dongzhi Tableland Area of the Loess Plateau of Eastern Gansu—A Case Study of Ning County Area, North China." Water 14, no. 22 (November 8, 2022): 3601. http://dx.doi.org/10.3390/w14223601.
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Groundwater plays an irreplaceable role in all aspects of the Loess Plateau. In this study, the loess phreatic water (LPW) and bedrock phreatic water (BPW) in the Ning County area (NCA) were sampled and analyzed, and the characteristics and controlling factors of groundwater were determined by using statistical analysis, hydrochemical methods, and hydrogeochemical simulation. The results indicated that the groundwater in the NCA was alkaline as a whole, and the average pH values of LPW and BPW were 8.1 and 7.8, respectively. The mean values of TDS concentrations of LPW and BPW were 314.9 mg/L and 675.3 mg/L, and the mean values of TH contents were 194.6 mg/L and 286.6 mg/L, respectively, which were mainly divided into hard fresh water. The Piper diagram illustrated that the hydrochemical type of groundwater in the NCA was mainly the HCO3·Ca type. The main recharge source of groundwater was atmospheric precipitation, and it was affected by evaporation to a certain extent. The linear relationships of δ18O and δ2H of LPW and BPW were δ2H = 6.998δ18O − 3.802 (R2 = 0.98) and δ2H = 6.283δ18O − 10.536 (R2 = 0.96), respectively. Hydrochemical analysis indicated that the groundwater in the NCA was mainly controlled by rock weathering and cation exchange. BPW was affected by the dissolution of gypsum. The possible mineral phases were identified on the basis of the main soluble minerals in the aquifer, and hydrogeochemical reverse simulations were performed. The dissolution of calcite, illite, and hornblende, and the precipitation of dolomite, plagioclase, and microcline occurred on both the LPW and BPW pathways.
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Obiri-Nyarko, Franklin, Stephen Junior Asugre, Sandra Vincentia Asare, Anthony Appiah Duah, Anthony Yaw Karikari, Jolanta Kwiatkowska-Malina, and Grzegorz Malina. "Hydrogeochemical Studies to Assess the Suitability of Groundwater for Drinking and Irrigation Purposes: The Upper East Region of Ghana Case Study." Agriculture 12, no. 12 (November 22, 2022): 1973. http://dx.doi.org/10.3390/agriculture12121973.
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Groundwater is increasingly being used to help meet the Sustainable Development Goals (SDGs) 2 and 6 in many parts of the world, including Ghana. Against this background, hydrogeochemical and multivariate statistical studies were conducted to determine the physicochemical characteristics and suitability of groundwater in some agrarian communities in the Upper East Region of Ghana for drinking and irrigational farming. Additional analyses were also performed to identify potential health risks associated with the groundwater use and to better understand the hydrogeochemical processes controlling groundwater evolution for its effective management. The results showed that the groundwater is typically fresh; moderate to very hard in character; undersaturated with calcite, dolomite, halite, and gypsum; and supersaturated with quartz and amorphous silica. The physicochemical characteristics of the groundwater are controlled by both anthropogenic and natural activities/processes, such as fertilizer application, irrigation return flows, rock weathering, and forward/reverse cation exchange. The total dissolved solids (TDS) (165–524 mg/L), electrical conductivity (EC) (275–873 μS/cm), sodium percentage (Na%; 9.05–17.74%), magnesium ratios (MR) (29.25–53.3%), permeability index (PI) (36.6–74.6%), and sodium adsorption ratio (SAR) (0.20–0.51) point to the possibility of using the groundwater for irrigation, however, with some salinity control. The water quality and health risk analysis also revealed that the groundwater can be used for drinking; however, the high concentrations of fluoride, which can cause noncarcinogenic health issues such as dental and skeletal fluorosis in both adults and children, must be reduced to the WHO required level of 1.5 mg/L.
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Iqbal, Javed, Chunli Su, Abdur Rashid, Nan Yang, Muhammad Yousuf Jat Baloch, Shakeel Ahmed Talpur, Zahid Ullah, et al. "Hydrogeochemical Assessment of Groundwater and Suitability Analysis for Domestic and Agricultural Utility in Southern Punjab, Pakistan." Water 13, no. 24 (December 14, 2021): 3589. http://dx.doi.org/10.3390/w13243589.
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Groundwater is a critical water supply for safe drinking water, agriculture, and industry worldwide. In the Khanewal district of Punjab, Pakistan, groundwater has severely deteriorated during the last few decades due to environmental changes and anthropogenic activities. Therefore, 68 groundwater samples were collected and analyzed for their main ions and trace elements to investigate the suitability of groundwater sources for drinking and agricultural purposes. Principal component analysis (PCA) and cluster analysis (CA) were employed to determine the major factors influencing groundwater quality. To assess the groundwater’s appropriateness for drinking and irrigation, drinking and agricultural indices were used. The pH of the groundwater samples ranged from 6.9 to 9.2, indicating that the aquifers were slightly acidic to alkaline. The major cations were distributed as follows: Na+ > Ca2+ > Mg2+ > K+. Meanwhile, the anions are distributed as follows: HCO3− > SO42− > Cl− > F−. The main hydrochemical facies were identified as a mixed type; however, a mixed magnesium, calcium, and chloride pattern was observed. The reverse ion exchange process helps in exchanging Na+ with Ca2+ and Mg2+ ions in the groundwater system. Rock weathering processes, such as the dissolution of calcite, dolomite, and gypsum minerals, dominated the groundwater hydrochemistry. According to the Weight Arithmetic Water Quality Index (WAWQI), 50% of the water samples were unsafe for drinking. The Wilcox diagram, USSL diagram, and some other agricultural indices resulted in around 32% of the groundwater samples being unsuitable for irrigation purposes. The Khanewal’s groundwater quality was vulnerable due to geology and the influence of anthropogenic activities. For groundwater sustainability in Khanewal, management strategies and policies are required.
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Prayitno, Budi, and Susilo Susilo. "Geology Of Tanjung Medan ,Rokan IV Koto , Rokan Hulu District, Riau Province." Journal of Geoscience, Engineering, Environment, and Technology 3, no. 2 (June 1, 2018): 123. http://dx.doi.org/10.24273/jgeet.2018.3.2.1597.
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The Administrative of research area has been in Tanjung Medan, Rokan IV Koto, Rokan Hulu, Riau Province and geographically located at 0 ° 37 '28.488 "- 0 ° 40' 10.3692" LU and 100 ° 24 '55.6884 "- 100 ° 27 '37.5804 "BT. Research method used approach method and laboratory analysis to get data of geology modeling and re-construction of geological history in research area. Based on surface observation, the geology of research area consists of Slate (Permian-carbon), Granite intrusion (Permian-Trias) with distribution SouthWest-SouthEast on the center of map. Arenite Sandstone unit (Easly Eocene) unconformity with slate on the bottom. Alluvial Rokan river crosses all type off rocks from north to south of map. While structure growth in the research area have been joints structure with main stress Southwest-NorthEast, its similar with trend tectonic setting of Sumatra island, on the other hand reverse fault indicates the formation of a basin of extension stress in the early Eocene. the formation of basins in basement rocks begun at the time of the formation of the north-south trending northern form of the fault block forming horst and graben as well as accommodated the precipitation of pre-tertiary clastic materials. Whereas the Oligocene trans-tensional compression system accommodating the sedimentation system in the formed of arenite sandstone (SBPa) unconformity above the basement rocks simultaneously on the basin base decrease. The distribution of arenite sandstones based on the geological reconstruction covering all parts of the rock distribution which then undergoes the same weathering process of the formation of Bukit Barisan volcanic path that controls the development of geological structure up to the present.
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Peng, Chen, Yuanming Liu, Huiyu Chen, Qiaowei Yuan, Qingzhi Chen, Shilong Mei, and Zhonghu Wu. "Analysis of Hydrogeochemical Characteristics of Tunnel Groundwater Based on Multivariate Statistical Technology." Geofluids 2021 (December 6, 2021): 1–16. http://dx.doi.org/10.1155/2021/4867942.
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Following tunnel excavation, which is influenced by hydraulic fracturing and geological structure, a series of hydrochemical reactions occur in the karst aquifer, which has a significant impact on groundwater hydrology and the earth process. Based on five sets of 38 samples collected in the Tongzi Tunnel in 2020 and 2021, the main geochemical processes and water quality conditions of the karst aquifer system during tunnel construction were revealed by multivariate statistical analysis and graphical methods. The results showed that water-rock action is the main mechanism controlling groundwater chemistry in the study area; HCO3-, Ca2+, and Mg2+ are associated with the widely distributed carbonate rocks in the study area. SO42- is derived from gypsum and sulfate rocks and special strata, which are another important source of Ca2+. Sodium-containing silicates and reverse cation exchange as the causal mechanisms of Na+ whereas F- is derived from fluorite. According to the mineral saturation index calculations, the dissolution and precipitation of minerals such as alum, gypsum, calcite, dolomite, and salt rock have an important influence on the main chemical components in water. The 38 samples were subjected to cluster analysis, and the results could be classified into seven categories. The representative clusters 1, 3, and 5 were selected for principal component analysis. Clusters 1 and 5 of groundwater represent weathering, dissolution, and ion exchange of carbonate and sulfate rocks and are closely related to the lithologic limestone, limestone intercalated with carbonaceous mudstone, carbonaceous mudstone, and coal-measure strata in the aquifer. Cluster 3 is dominated by upper surface river water and characterizes the geochemistry in natural water bodies dominated by the dissolution of carbonate, sulfate, and salt rocks. Finally, groundwater quality is mostly found in Class IV, with NO3- and F- being the main contaminants in the water.
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Draebing, Daniel. "Identification of rock and fracture kinematics in high alpine rockwalls under the influence of elevation." Earth Surface Dynamics 9, no. 4 (August 17, 2021): 977–94. http://dx.doi.org/10.5194/esurf-9-977-2021.
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Abstract. In alpine environments, tectonic processes, past glaciation and weathering processes fracture rock and prepare or trigger rockfalls, which are important processes of rock slope evolution and natural hazards. In this study, I quantify thermally and ice-induced rock and fracture kinematics and place these in the context of their role in producing rockfall and climate change. I conducted laboratory measurements on intact rock samples and installed temperature loggers and crackmeters at four rockwalls reaching from 2585 to 2935 m in elevation in the Hungerli Valley, Swiss Alps. My laboratory data show that thermal expansion followed three phases of rock kinematics, which resulted in a hysteresis effect. In the field, control crackmeters on intact rock reflected these temperature phases, and based on thermal expansion coefficients of these observed phases, I modelled thermal stress. Model results show that thermal stress magnitudes were predominantly below rock strengths. Crackmeters across fractures revealed fracture opening during cooling and reverse closing behaviour during warming on daily timescales. Elevation-dependent snow cover controlled the number of daily temperature changes and thermal stresses affecting both intact and fractured rock, while the magnitude is controlled by topographic factors influencing insolation. On a seasonal scale, slow ice-segregation-induced fracture opening can occur within lithology-dependent temperature regimes called frost cracking windows. Shear plane dipping controlled whether fractures opened or closed irreversibly with time due to thermally induced block crawling on an annual scale. Climate change will shorten snow duration and increase temperature extremes and will, therefore, affect the number and the magnitude of thermal changes and associated stresses. Earlier snowmelt in combination with temperature increase will shift the ice-induced kinematic processes to higher elevations. In conclusion, climate change will affect and change rock and fracture kinematics and, therefore, change rockfall patterns in alpine environments. Future work should quantify rockfall patterns and link these patterns to climatic drivers.
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Varkouhi, Shahab, Nicholas J. Tosca, and Joseph A. Cartwright. "Pore-water chemistry: A proxy for tracking the signature of ongoing silica diagenesis." Journal of Sedimentary Research 90, no. 9 (September 1, 2020): 1037–67. http://dx.doi.org/10.2110/jsr.2020.56.
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ABSTRACT Silica diagenesis leads to dramatic petrophysical variations in the host sediment across the depth of an opal-A to opal-CT transition zone. Predicting the present-day diagenetic status of opal-A to opal-CT transition zones, i.e., active versus fossilized fronts, is essential to constraining the drivers that control abrupt changes in the physical state of sediment. This study assesses whether there are modern signatures of ongoing silica diagenesis in the sediment pore water, and demonstrates the potential for pore-water-chemistry profiles for distinguishing between active opal-CT precipitation and fossil transition zones. Pore-water chemistry, mineralogy, and thermodynamic analyses of the Ocean Drilling Program Wells 794 and 795 indicate that solubility equilibrium has been reached with respect to opal-CT in the transition zones captured by the Neogene biosilica in the Sea of Japan. Even though silica dissolution might be triggering a reverse-weathering process, the equilibrium reached with respect to diagenetic opal strongly suggests that the silica drop across the transition zones is mainly influenced by active opal-A to opal-CT transformation. Owing to abrupt petrophysical variations associated with opal-CT formation, other interstitial profiles—major ions and primary parameters—have been influenced by silica diagenesis. The extremely low silica diffusion fluxes in the sediment, the low permeability of host sediment, and the occurrence of considerable pore-water loss at the depth of the transition zone all support this conclusion that the dissolved species have not been diffused in the sediment at rates comparable to those by pore-water advection. Advection and diffusion, however, appear to have ceased recently because they have failed to smooth the signature of ongoing silica diagenesis. The porosity drop during opal-A to opal-CT diagenesis at Sites 794 and 795 is principally attributed to chemically induced anomalous compaction, causing the sediment framework to lose its strength under fragmentation and extensive opal-A dissolution.
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Dhesini, Meenalakshmi, and Muttharam Madhavan. "Hydrogeo chemical process characterization and ecological impacts of groundwater in around Noyyal river coimbatore district, Tamil Nadu, India." Thermal Science, no. 00 (2021): 211. http://dx.doi.org/10.2298/tsci200814211d.
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In this research article details the hydrogeo chemical process characterization and ecological impact of groundwater was carried out around the Noyyal river, Coimbatore region, India. In pre and post monsoon region, the surrounding shallow wells groundwaters are used for this trial experiments (25 samples) and its major cations and anions are also observed. From the analytical results it?s identify that majority of ions pursue the succeeding sequence Cl>Na>Ca>Mg>HCO3>SO4 during both seasons. About sixty percentages of the groundwater samples was lying in under salinewater group during both seasons. The dying industries use many chemicals throughout the dyes process, resulted in high content of Cl and sodium within the groundwater. During the post and pre monsoon, 42 and 45 percent of samples were collected. It revealed that the absorption of sodium and chloride were surpassed the allowable percentage. About 55% of the examples fall in Na-Cl sort, which plainly demonstrates the prominent impact of enterprises profluent and geochemical measures on the nature of water. Spatial distribution indicates that all the major ions increase towards northern and central part of the region. Strong positive correlation for Cl with EC, Ca, Mg and Na were observed during both seasons due to influence of anthropogenic impact and natural processes. The Kelly?s and Magnesium Hazards about 50% of the samples exceeded above the limit indicates unsuitable for agriculture purpose during the season of pre and post monsoon. In current location, the process like silicate weathering and reverse ion exchange establishing the groundwater chemical properties. This study further reveals that in the proximity of industries the ground water possesses higher concentration of associated ions is found around the industries due to the ecological impact of effluents. Hence it is realised that to recover the groundwater quality of this region, it is essential to treat the effluent effectively.
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Dill, Harald G., Sobhi Nasir, and Hamad Al-Saad. "Lithological and structural evolution of the northern sector of Dukhan anticline, Qatar, during the early Tertiary: with special reference to sequence stratigraphic bounding surfaces." GeoArabia 8, no. 2 (April 1, 2003): 201–26. http://dx.doi.org/10.2113/geoarabia0802201.
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ABSTRACT Early Tertiary sediments are widely exposed in Qatar and only in coastal areas and a few places inland do Holocene deposits mask them. The variable resistance to weathering of the Tertiary sediments is responsible for the general low-relief landscape interspersed with flat-topped hills, the most prominent of which are in western Qatar where they are the surface expression of the Dukhan anticline. The early Tertiary was a time of shallow-marine sedimentation and several transgressive and regressive cycles occurred. Sedimentation began on a dolomitic carbonate shelf, which gave way to a mixed carbonate-siliciclastic shelf that became increasingly calcitic. Coarsening-upward sequences with fine-grained muddy sediments at the base and grainstones and boundstones on top attested to a cyclic change in the energy regime. Small-scale cycles and major unconformities resulted from eustatic sea-level changes. In the Dukhan study area, the most prominent sequence boundary was near the Ypresian-Lutetian boundary. Following this hiatus, a Lutetian transgressive system tract evolved that was terminated by a maximum flooding surface correlated with the named MFS Pg20. Minor unconformities and NE-trending faults of post-Miocene age resulted from the interplay of local diapiric salt movements in the Dukhan anticline and a regionally changing stress field. Extensional faulting was succeeded by a compressional phase that caused the reactivation of some normal faults as steeply dipping reverse faults. Diagenetic processes and the pervasive etching of the landscape formed ferrous, siliceous, and gypsiferous duricrusts. Phosphate was reworked and concentrated above the Ypresian-Lutetian unconformity. Ferricretes were derived from iron-bearing phyllosilicates and disulfides. Ferric iron-oxide hydrates were the result of oxidizing conditions but their parent material furnished evidence of less-oxygenated conditions and a rising sea level during the Lutetian transgression. The studies provided information on the economic potential of aggregates, clay, hydraulic binders, and building stones, and the prediction of subsidence-prone areas.
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Li, Xinyan, Xiaopeng Liu, Jianguo Du, Yueju Cui, and Fengxia Sun. "Hydrogeochemical Characteristics of the Haiyuan-Liupanshan Seismic Belt at the Northeastern Edge of the Tibet Plateau." Geofluids 2022 (May 17, 2022): 1–17. http://dx.doi.org/10.1155/2022/6894229.
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The hydrogeochemical characteristics and groundwater recharge environments along the deep-cut Haiyuan-Liupanshan fault zone (HLFZ) were investigated by major ion and isotopic compositions (δ18O and δD) of the water samples collected at 14 sites from 2016 to 2017. The Schukalev classification method, fuzzy membership function, the proportion coefficients of major ions and principal component analysis (PCA) were adopted to analysis the hydrogeochemistry, water quality, origins and controlling factors of groundwater. In terms of chemical types, the sites along HLFZ can be divided into two groups. Specifically, the Group 1 is in the north and west part of the HLFZ and the water samples are characterized by higher salinity and enriched in Na+ and SO42-, reflecting the control of evaporate dissolution in cretaceous and tertiary aquifers, reverse ionic exchange, stronger water-rock reaction and deep fluids. The higher concentrations of Ca2+ + Mg2+ and HCO3- were found in Group 2, which is located in the southeast of the HLFZ and may be attributed to carbonate weathering and the recharge of karst fissure water from ordovician dolomite and limestone. Contamination of groundwater in HLFZ is severe, with 78.6% of the sites classified as grade V, which means they cannot be used for drinking water or agriculture. The primary contaminants found in Group 1 are TDS, Na+, Cl- and SO42- and the exceedance in NO3-and pH value affect water quality in the Group 2. The 18O and δD values of groundwater in HLFZ indicated that meteoric water contributed dominantly to the groundwater and it was influenced by the water cycle and water-rock reaction. Furthermore, tectonic movement, seismicity, and the level of deformation along different segments of HLFZ are important factors in the migration of deep to shallow groundwater, and water-rock reactions during groundwater migration, which results in differences in chemical composition of the groundwater between Group 1 and Group 2. Most of the sites with higher TDS in HLFZ fall on the a higher stress state region (represented by a low b value<0.75), which reflected a possible evidence of seismic activity affected the hydrogeochemistry of groundwater.
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Chen, Man Ying, Yong Jun Zhang, Jing Tao Han, and De Ming Yao. "The Full Immersion Test Research of Refractory Weathering Steel." Advanced Materials Research 941-944 (June 2014): 965–69. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.965.
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The paper mainly studied the corrosion properties of refractory weathering steel under chloride ion erosion environment. The full immersion tests on refractory weathering steel and carbon steel Q235 were conducted; and then a comparative analysis from the perspective of the corrosion weightlessness, the macro and micro morphology of rust layers have been made. Results indicated that refractory weathering steel and carbon steel corrosion weightlessness is relatively close to the early stage of corrosion, but the trend is reversed in the mid to late; refractory weathering steel corrosion weightlessness gradually decline, but the carbon steel’s is first increase then decrease. The carbon steel is mainly pitting corrosion, while refractory weathering steel develops general corrosion under chloride ion erosion environment. Rust layers of carbon steel are loose, hollow, and uneven. As the corrosion time goes on, the thickness of refractory weathering steel’s rust layers continuously thickening and the rust layers’ integrity are gradually increasing. The corrosion depth of refractory weathering steel is less than carbon steel’s; so does the longitudinal corrosion. This is because the microstructure of carbon steel is coarse pearlite and ferrite while the refractory weathering steel is granular bainite; the grain boundaries of carbon steel have more inclusions, especially MnS that is easily dissolved in chloride ion erosion environment. It is found that alloying elements Cr, Cu are enriched in the rust layers of refractory weathering steel by means of energy dispersive X-ray spectroscopy (EDS). The enrichment of these alloy elements in the rust layers improves the rust layer density, so that the uniform, dense, smooth rust layers formed on the surface of refractory weathering steel play a significant protective film to improve the substrate resistance corrosion.
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Petrillo, Marta, Jakub Sandak, Paolo Grossi, and Anna Sandak. "Chemical and appearance changes of wood due to artificial weathering – Dose–response model." Journal of Near Infrared Spectroscopy 27, no. 1 (January 22, 2019): 26–37. http://dx.doi.org/10.1177/0967033518825364.
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The aim of this study was to assess a model for the surface degradation kinetics of natural wood exposed to artificial weathering. The photochemical and physical processes of weathering result in simultaneous changes of both the wood matrix composition (i.e. lignin content, cellulose crystallinity index, cellulose polymerization degree) and wood’s appearance (i.e. colour, gloss, roughness). European larch, a popular cladding material, was used for experimental samples. Weathering was conducted in a QUV artificial weathering machine for 672 h according to the EN927-6 standard. The response of wood was assessed using multi-sensor measurements. Results revealed that changes in colour are evident already after 28 h of artificial weathering, with an increase in a* and b*, and a decrease in L*. That initial trend was reversed afterward, with the colour changing to grey. Due to the particular shape of the curves representing colour coordinates, it is difficult to use CIE L* a* b* parameters to model the weathering dose. However, the degradation curve established for selected near infrared bands was useful to build a dose–response model of wood surface degradation. In all cases, a clear trend of change in absorbance values that progressed along with the weathering dose was observed. These curves, unlike the CIE L* a* b* values, are monotonic, meaning that dose value corresponded with only one value of absorbance. Principal component analysis of the near infrared spectra allowed clustering of the spectra by different dose classes, with the main differentiation in the reference class and in the final class (maximum dose). It was found that the discrimination between spectra at diverse cumulative weathering doses was more evident for earlywood than for latewood. This confirms the hypothesis that degradation kinetics differ depending on the anatomical configuration of wood. This research is a first step for establishing dose–response model for natural weathering, where precise quantification of weathering parameters is more challenging.
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Renforth, P., and J. S. Campbell. "The role of soils in the regulation of ocean acidification." Philosophical Transactions of the Royal Society B: Biological Sciences 376, no. 1834 (August 4, 2021): 20200174. http://dx.doi.org/10.1098/rstb.2020.0174.
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Soils play an important role in mediating chemical weathering reactions and carbon transfer from the land to the ocean. Proposals to increase the contribution of alkalinity to the oceans through ‘enhanced weathering’ as a means to help prevent climate change are gaining increasing attention. This would augment the existing connection between the biogeochemical function of soils and alkalinity levels in the ocean. The feasibility of enhanced weathering depends on the combined influence of what minerals are added to soils, the formation of secondary minerals in soils and the drainage regime, and the partial pressure of respired CO 2 around the dissolving mineral. Increasing the alkalinity levels in the ocean through enhanced weathering could help to ameliorate the effects of ocean acidification in two ways. First, enhanced weathering would slightly elevate the pH of drainage waters, and the receiving coastal waters. The elevated pH would result in an increase in carbonate mineral saturation states, and a partial reversal in the effects of elevated CO 2 . Second, the increase in alkalinity would help to replenish the ocean's buffering capacity by maintaining the ‘Revelle Factor’, making the oceans more resilient to further CO 2 emissions. However, there is limited research on the downstream and oceanic impacts of enhanced weathering on which to base deployment decisions. This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.
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Elsayed, Salah, Hend Hussein, Farahat S. Moghanm, Khaled M. Khedher, Ebrahem M. Eid, and Mohamed Gad. "Application of Irrigation Water Quality Indices and Multivariate Statistical Techniques for Surface Water Quality Assessments in the Northern Nile Delta, Egypt." Water 12, no. 12 (November 24, 2020): 3300. http://dx.doi.org/10.3390/w12123300.
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Under sustainable development conditions, the water quality of irrigation systems is a complex issue which involves the combined effects of several surface water management parameters. Therefore, this work aims to enhance the surface water quality assessment and geochemical controlling mechanisms and to assess the validation of surface water networks for irrigation using six Water Quality Indices (WQIs) supported by multivariate modelling techniques, such as Principal Component Regression (PCR), Support Vector Machine Regression (SVMR) and Stepwise Multiple Linear Regression (SMLR). A total of 110 surface water samples from a network of surface water cannels during the summers of 2018 and 2019 were collected for this research and standard analytical techniques were used to measure 21 physical and chemical parameters. The physicochemical properties revealed that the major ions concentrations were reported in the following order: Ca2+ > Na+ > Mg2+ > K+ and alkalinity > SO42− > Cl− > NO3− > F−. The trace elements concentrations were reported in the following order: Fe > Mn > B > Cr > Pb > Ni > Cu > Zn > Cd. The surface water belongs to the Ca2+-Mg2+-HCO3− and Ca2+-Mg2+-Cl−-SO42− water types, under a stress of silicate weathering and reverse ion exchange process. The computation of WQI values across two years revealed that 82% of samples represent a high class and the remaining 18% constitute a medium class of water quality for irrigation use with respect to the Irrigation Water Quality (IWQ) value, while the Sodium Percentage (Na%) values across two years indicated that 96% of samples fell into in a healthy class and 4% fell into in a permissible class for irrigation. In addition, the Sodium Absorption Ratio (SAR), Permeability Index (PI), Kelley Index (KI) and Residual Sodium Carbonate (RSC) values revealed that all surface water samples were appropriate for irrigation use. The PCR and SVMR indicated accurate and robust models that predict the six WQIs in both datasets of the calibration (Cal.) and validation (Val.), with R2 values varying from 0.48 to 0.99. The SMLR presented estimated the six WQIs well, with an R2 value that ranged from 0.66 to 0.99. In conclusion, WQIs and multivariate statistical analyses are effective and applicable for assessing the surface water quality. The PCR, SVMR and SMLR models provided robust and reliable estimates of the different indices and showed the highest R2 and the highest slopes values close to 1.00, as well as minimum values of RMSE in all models.
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Koehl, Jean-Baptiste P., Steffen G. Bergh, and Klaus Wemmer. "Neoproterozoic and post-Caledonian exhumation and shallow faulting in NW Finnmark from K–Ar dating and <i>p</i>∕<i>T</i> analysis of fault rocks." Solid Earth 9, no. 4 (July 20, 2018): 923–51. http://dx.doi.org/10.5194/se-9-923-2018.
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Abstract. Well-preserved fault gouge along brittle faults in Paleoproterozoic, volcano-sedimentary rocks of the Raipas Supergroup exposed in the Alta–Kvænangen tectonic window in northern Norway yielded latest Mesoproterozoic (approximately 1050 ± 15 Ma) to mid-Neoproterozoic (approximately 825–810 ± 18 Ma) K–Ar ages. Pressure–temperature estimates from microtextural and mineralogy analyses of fault rocks indicate that brittle faulting may have initiated at a depth of 5–10 km during the opening of the Asgard Sea in the latest Mesoproterozoic–early Neoproterozoic (approximately 1050–945 Ma) and continued with a phase of shallow faulting to the opening of the Iapetus Ocean–Ægir Sea and the initial breakup of Rodinia in the mid-Neoproterozoic (approximately 825–810 Ma). The predominance and preservation of synkinematic smectite and subsidiary illite in cohesive and non-cohesive fault rocks indicate that Paleoproterozoic basement rocks of the Alta–Kvænangen tectonic window remained at shallow crustal levels (< 3.5 km) and were not reactivated since mid-Neoproterozoic times. Slow exhumation rate estimates for the early–mid-Neoproterozoic (approximately 10–75 m Myr−1) suggest a period of tectonic quiescence between the opening of the Asgard Sea and the breakup of Rodinia. In the Paleozoic, basement rocks in NW Finnmark were overthrusted by Caledonian nappes along low-angle thrust detachments during the closing of the Iapetus Ocean–Ægir Sea. K–Ar dating of non-cohesive fault rocks and microtexture mineralogy of cohesive fault rock truncating Caledonian nappe units show that brittle (reverse) faulting potentially initiated along low-angle Caledonian thrusts during the latest stages of the Caledonian Orogeny in the Silurian (approximately 425 Ma) and was accompanied by epidote–chlorite-rich, stilpnomelane-bearing cataclasite (type 1) indicative of a faulting depth of 10–16 km. Caledonian thrusts were inverted (e.g., Talvik fault) and later truncated by high-angle normal faults (e.g., Langfjorden–Vargsundet fault) during subsequent, late Paleozoic, collapse-related widespread extension in the Late Devonian–early Carboniferous (approximately 375–325 Ma). This faulting period was accompanied by quartz- (type 2), calcite- (type 3) and laumontite-rich cataclasites (type 4), whose cross-cutting relationships indicate a progressive exhumation of Caledonian rocks to zeolite-facies conditions (i.e., depth of 2–8 km). An ultimate period of minor faulting occurred in the late Carboniferous–mid-Permian (315–265 Ma) and exhumed Caledonian rocks to shallow depth at 1–3.5 km. Alternatively, late Carboniferous (?) to early–mid-Permian K–Ar ages may reflect late Paleozoic weathering of the margin. Exhumation rates estimates indicate rapid Silurian–early Carboniferous exhumation and slow exhumation in the late Carboniferous–mid-Permian, supporting decreasing faulting activity from the mid-Carboniferous. NW Finnmark remained tectonically quiet in the Mesozoic–Cenozoic.