Cao Dingfeng, B. Shi, Hong-hu Zhu, C. Tang, Song Zhanpu, Wei Guangqing, A. Garg
The infiltration and distribution of water through unsaturated soil determine its mechanical and hydrological properties. However, there are few methods that can accurately capture the spatial distribution of moisture inside soil. This study aims to demonstrate the use of actively heated fiber optic (AHFO) and Brillouin optical time domain analysis (BOTDA) technologies for monitoring soil moisture distribution as well as strain distribution. In addition to a laboratory model test, finite element analyses were conducted to interpret the measurements. During the experiment, the fine particle migration was also measured to understand its influence on soil hydraulic conductivity. The results of the experiment indicate that (i) for a soil that has never experienced a watering-dewatering cycle, water infiltration can be accurately calculated using the Richards’ equation; (ii) migration of fine soil particles caused by the watering-dewatering cycle significantly increases the hydraulic conductivity; and (iii) two critical zones (drainage and erosion) play significant roles in determining the overall hydraulic conductivity of the entire soil. This study provides a new method for monitoring the changes in soil moisture, soil strain, and hydraulic conductivity. The observations suggest that the effect of fine particles migration should be considered while evaluating soil moisture distribution and water movement.
{"title":"Characterization of Soil Moisture Distribution and Movement Under the Influence of Watering-dewatering Using AHFO and BOTDA Technologies","authors":"Cao Dingfeng, B. Shi, Hong-hu Zhu, C. Tang, Song Zhanpu, Wei Guangqing, A. Garg","doi":"10.2113/EEG-2117","DOIUrl":"https://doi.org/10.2113/EEG-2117","url":null,"abstract":"\u0000 The infiltration and distribution of water through unsaturated soil determine its mechanical and hydrological properties. However, there are few methods that can accurately capture the spatial distribution of moisture inside soil. This study aims to demonstrate the use of actively heated fiber optic (AHFO) and Brillouin optical time domain analysis (BOTDA) technologies for monitoring soil moisture distribution as well as strain distribution. In addition to a laboratory model test, finite element analyses were conducted to interpret the measurements. During the experiment, the fine particle migration was also measured to understand its influence on soil hydraulic conductivity. The results of the experiment indicate that (i) for a soil that has never experienced a watering-dewatering cycle, water infiltration can be accurately calculated using the Richards’ equation; (ii) migration of fine soil particles caused by the watering-dewatering cycle significantly increases the hydraulic conductivity; and (iii) two critical zones (drainage and erosion) play significant roles in determining the overall hydraulic conductivity of the entire soil. This study provides a new method for monitoring the changes in soil moisture, soil strain, and hydraulic conductivity. The observations suggest that the effect of fine particles migration should be considered while evaluating soil moisture distribution and water movement.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115399759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The geotechnical literature contains claims that testing as few as three to 10 samples suffices for characterizing such rock properties as unconfined compressive strength, but from the perspective of basic statistics, such small numbers are unlikely to provide acceptable estimates of true means and standard deviations and are even less likely to yield accurate assessments of normality. Statistically based decisions are overly risky when based on dubious statistics: problematic estimates may be tolerable for reconnaissance studies, evaluation of small sites, projects with minimal hazards and risk, or when combined with high factor-of-safety designs, but not when potential loss is considerable, designs are less conservative, or statistical work depends on assumptions of normality, such as in the case of confidence intervals, t-tests, statistical power, and standard risk analysis. In this study, bootstrapping experiments with artificial populations confirm that 30 to 300 samples are appropriate with Gaussian distributions, depending on needs, but higher numbers may be required for populations with irregular or skewed distributions. Planning for large projects, trying to improve economy without loss of safety in designs, and statistical research (e.g., creating accurate regression models) all require more information than is likely to be available about the amounts and patterns of variability exhibited by specific rock units. Therefore, a national registry or state registries of engineering test results would comprise a valuable advance for the engineering geology profession.
{"title":"Are Three to Ten Tests Enough to Characterize a Rock Property?","authors":"N. Wells, A. Shakoor","doi":"10.2113/EEG-2176","DOIUrl":"https://doi.org/10.2113/EEG-2176","url":null,"abstract":"\u0000 The geotechnical literature contains claims that testing as few as three to 10 samples suffices for characterizing such rock properties as unconfined compressive strength, but from the perspective of basic statistics, such small numbers are unlikely to provide acceptable estimates of true means and standard deviations and are even less likely to yield accurate assessments of normality. Statistically based decisions are overly risky when based on dubious statistics: problematic estimates may be tolerable for reconnaissance studies, evaluation of small sites, projects with minimal hazards and risk, or when combined with high factor-of-safety designs, but not when potential loss is considerable, designs are less conservative, or statistical work depends on assumptions of normality, such as in the case of confidence intervals, t-tests, statistical power, and standard risk analysis. In this study, bootstrapping experiments with artificial populations confirm that 30 to 300 samples are appropriate with Gaussian distributions, depending on needs, but higher numbers may be required for populations with irregular or skewed distributions. Planning for large projects, trying to improve economy without loss of safety in designs, and statistical research (e.g., creating accurate regression models) all require more information than is likely to be available about the amounts and patterns of variability exhibited by specific rock units. Therefore, a national registry or state registries of engineering test results would comprise a valuable advance for the engineering geology profession.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126147701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Near-surface seismic refraction tomography imaged the basal contact of the Upper Cambrian silica-rich Mount Simon Formation with that of the underlying Precambrian granite in central Wisconsin. The discrimination between the Mount Simon and underlying non-conformable contact with Precambrian rocks was based upon a p-wave velocity of 1,700 m/s. Refraction tomography imaged deep, broad tidal channels within the Mount Simon consistent with the inference that Mount Simon was deposited in a high-energy near-shore, probably fluvial environment. The Mount Simon is an arenite that has high commercial value.
{"title":"Stratigraphic Analysis with Refraction Tomography","authors":"P. Hutchinson, Maggie H. Tsai","doi":"10.2113/EEG-2127","DOIUrl":"https://doi.org/10.2113/EEG-2127","url":null,"abstract":"\u0000 Near-surface seismic refraction tomography imaged the basal contact of the Upper Cambrian silica-rich Mount Simon Formation with that of the underlying Precambrian granite in central Wisconsin. The discrimination between the Mount Simon and underlying non-conformable contact with Precambrian rocks was based upon a p-wave velocity of 1,700 m/s. Refraction tomography imaged deep, broad tidal channels within the Mount Simon consistent with the inference that Mount Simon was deposited in a high-energy near-shore, probably fluvial environment. The Mount Simon is an arenite that has high commercial value.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125017795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water pollution is the most important reason to monitor and assess water quality. The chemical, physical, and biological quality of natural waters may be affected by anthropogenic activities such as industrial, urban, and agricultural activities. In the present study, the water quality of the Zarrineh River, one of the main rivers supplying water in the northwest of Iran, was investigated. A total of 21 sites were selected for surface water sampling during spring and winter (dry and wet) seasons. The concentrations of the metals aluminum, iron, barium, chromium, arsenic, copper, manganese, nickel, selenium, lead, and zinc were determined for source partition and heavy metal pollution index (HMPI) assessment during both the spring and winter seasons. Four important dominant factors in the principal component analysis depicted, in toto, 76.22 percent of the variance, with an initial eigenvalue greater than 1. The calculated HMPI for all the seasons and sampling stations was 66, fluctuating between 30 and 170 in single water sampling sites. The results showed that almost all locations fall into the high classes of the HMPI, but below the critical pollution index limit of 100. Apart from the gold mining establishments and industrial factories, the reasons for the increased concentrations of metals in the Zarrineh River may be attributed in particular to anthropogenic and mining activities.
{"title":"The Heavy Metals Pollution Index and Water Quality Monitoring of the Zarrineh River, Iran","authors":"Maryam Khalilzadeh Poshtegal, S. Mirbagheri","doi":"10.2113/EEG-1996","DOIUrl":"https://doi.org/10.2113/EEG-1996","url":null,"abstract":"\u0000 Water pollution is the most important reason to monitor and assess water quality. The chemical, physical, and biological quality of natural waters may be affected by anthropogenic activities such as industrial, urban, and agricultural activities. In the present study, the water quality of the Zarrineh River, one of the main rivers supplying water in the northwest of Iran, was investigated. A total of 21 sites were selected for surface water sampling during spring and winter (dry and wet) seasons. The concentrations of the metals aluminum, iron, barium, chromium, arsenic, copper, manganese, nickel, selenium, lead, and zinc were determined for source partition and heavy metal pollution index (HMPI) assessment during both the spring and winter seasons. Four important dominant factors in the principal component analysis depicted, in toto, 76.22 percent of the variance, with an initial eigenvalue greater than 1. The calculated HMPI for all the seasons and sampling stations was 66, fluctuating between 30 and 170 in single water sampling sites. The results showed that almost all locations fall into the high classes of the HMPI, but below the critical pollution index limit of 100. Apart from the gold mining establishments and industrial factories, the reasons for the increased concentrations of metals in the Zarrineh River may be attributed in particular to anthropogenic and mining activities.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114869921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Terrestrial laser scanning (TLS) is a surveying technology that has seen increasing use in the field of geosciences in recent years. One potential application for this technology is to aid in quantitative stratigraphy. Given a point cloud containing multiple lithologies, the points associated with a specific lithology can be analyzed to quantify the geometric characteristics of that lithology, such as apparent dip, thickness, and spacing. In this study, a semi-automated work flow to perform such a characterization is presented and applied to a case study from an oil sands pit mine in the Athabasca region of Alberta, Canada. The results obtained using data collected with mobile and static TLS systems are compared to evaluate the effects of the various measurements and resolutions on the resulting stratigraphic statistics. In addition, mobile data collected for a small portion of the pit that was actively being mined are compared over time to evaluate changes in sedimentary layering in the direction perpendicular to the pit face. This component of the study highlights the impact of data quality on the resulting interpretations and represents a potential methodology for enhancing three-dimensional quantitative spatial modeling in a sedimentary environment.
{"title":"Extraction and Comparison of Spatial Statistics For Geometric Parameters of Sedimentary Layers from Static and Mobile Terrestrial Laser Scanning Data","authors":"G. Walton, G. Fotopoulos, R. Radovanovic","doi":"10.2113/EEG-2068","DOIUrl":"https://doi.org/10.2113/EEG-2068","url":null,"abstract":"\u0000 Terrestrial laser scanning (TLS) is a surveying technology that has seen increasing use in the field of geosciences in recent years. One potential application for this technology is to aid in quantitative stratigraphy. Given a point cloud containing multiple lithologies, the points associated with a specific lithology can be analyzed to quantify the geometric characteristics of that lithology, such as apparent dip, thickness, and spacing. In this study, a semi-automated work flow to perform such a characterization is presented and applied to a case study from an oil sands pit mine in the Athabasca region of Alberta, Canada. The results obtained using data collected with mobile and static TLS systems are compared to evaluate the effects of the various measurements and resolutions on the resulting stratigraphic statistics. In addition, mobile data collected for a small portion of the pit that was actively being mined are compared over time to evaluate changes in sedimentary layering in the direction perpendicular to the pit face. This component of the study highlights the impact of data quality on the resulting interpretations and represents a potential methodology for enhancing three-dimensional quantitative spatial modeling in a sedimentary environment.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117034840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anchored retaining walls are restraining walls constructed using anchors to achieve the highest stiffness possible within economic considerations. Anchor length estimation has an important role in the study of the stability of anchored retaining walls. The purpose of this study was to investigate the anchor length using different proposed failure models and Kranz's classic model. In addition, several parametric studies were conducted to find reliable results in the stability analysis of retaining anchored walls with the aim of obtaining stable and shorter anchor lengths. A numerical study was carried out using Geo4 and Plaxis 8.6 software on the same standard profile as analytically studied so as to validate the proposed mechanical models. The failure models proposed in this work are shown to be a useful tool for obtaining stable and shorter anchor lengths for anchored retaining walls.
{"title":"Proposed Improvements To Analytical Models of Anchored Retaining Walls","authors":"B. F. Zohra, Belabed Lazhar, Rouaiguia Ammar","doi":"10.2113/EEG-2078","DOIUrl":"https://doi.org/10.2113/EEG-2078","url":null,"abstract":"\u0000 Anchored retaining walls are restraining walls constructed using anchors to achieve the highest stiffness possible within economic considerations. Anchor length estimation has an important role in the study of the stability of anchored retaining walls. The purpose of this study was to investigate the anchor length using different proposed failure models and Kranz's classic model. In addition, several parametric studies were conducted to find reliable results in the stability analysis of retaining anchored walls with the aim of obtaining stable and shorter anchor lengths. A numerical study was carried out using Geo4 and Plaxis 8.6 software on the same standard profile as analytically studied so as to validate the proposed mechanical models. The failure models proposed in this work are shown to be a useful tool for obtaining stable and shorter anchor lengths for anchored retaining walls.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128442465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shengyan Pu, Yaqi Hou, Jin Ma, Zou Yan, Liu Xu, Qingqing Shi, Sijia Qian, X. Pei
Serious soil erosion can endanger human survival and sustainable development. Therefore, simple and highly efficient soil stabilizers that can be used to treat loess soil, which has poor water stability and easily disintegrates, are a topic of concern for researchers. In this work, a biomass-based polymeric soil stabilizer (CXZ) was prepared using a “green” strategy with polymerization of carboxymethyl cellulose and xanthan gum. A direct shear test, unconfined compressive strength properties, water stability, and erosion resistance were systematically investigated to test the stabilization performance. The stabilizer agglomerated small loess particles into large aggregates through “coating” and “weaving” effects to increase the cohesion, water stability, and erosion resistance significantly, as demonstrated by Fourier transform infrared spectroscopy and scanning electron microscope. Furthermore, in a 30-day growth experiment, the number of alfalfa plants and the plant height in stabilized loess both increased with the increase in CXZ stabilizer concentration. This work provides insight into a novel biomass-based soil-curing agent, broadening its applications in loess remediation and soil erosion control.
{"title":"Stabilization Behavior and Performance of Loess Using a Novel Biomass-based Polymeric Soil Stabilizer","authors":"Shengyan Pu, Yaqi Hou, Jin Ma, Zou Yan, Liu Xu, Qingqing Shi, Sijia Qian, X. Pei","doi":"10.2113/EEG-2074","DOIUrl":"https://doi.org/10.2113/EEG-2074","url":null,"abstract":"\u0000 Serious soil erosion can endanger human survival and sustainable development. Therefore, simple and highly efficient soil stabilizers that can be used to treat loess soil, which has poor water stability and easily disintegrates, are a topic of concern for researchers. In this work, a biomass-based polymeric soil stabilizer (CXZ) was prepared using a “green” strategy with polymerization of carboxymethyl cellulose and xanthan gum. A direct shear test, unconfined compressive strength properties, water stability, and erosion resistance were systematically investigated to test the stabilization performance. The stabilizer agglomerated small loess particles into large aggregates through “coating” and “weaving” effects to increase the cohesion, water stability, and erosion resistance significantly, as demonstrated by Fourier transform infrared spectroscopy and scanning electron microscope. Furthermore, in a 30-day growth experiment, the number of alfalfa plants and the plant height in stabilized loess both increased with the increase in CXZ stabilizer concentration. This work provides insight into a novel biomass-based soil-curing agent, broadening its applications in loess remediation and soil erosion control.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126596786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When a destructive landslide happens, geologists may be recruited to be part of the team carrying out the emergency response. An emergency response situation requires geologists to quickly acquire needed geologic information during an intense and stressful assignment. There are five significant operational approaches that are essential to ensure success in this situation. First, the geologists should fully understand and remain focused on the objectives of the response mission. Second, the landslide area must be accessed safely when collecting needed data. From a team standpoint, an injury negatively affects available data and time. Third, the landslide information that is developed must be reliable within the context of the mission and be obtainable within a limited time. Fourth, given the constraints on data collection imposed by an emergency response situation, the degree of uncertainty associated with the findings will need to be explained to ensure subsequent decision-making is done on a sound basis. Fifth, the information needs to be communicated to different audiences, who will range from individual team members to groups of people affected by the landslide. Whether providing documentation or making a presentation, the geologist will need to engage them by explaining the landslide information so it speaks to their needs. Experience gained serving on teams for a huge landslide damming a river in Dominica, West Indies, in 1997 and a large rock slide that buried a major highway in California in 2006 illustrate these important aspects for ensuring success when investigating landslides during an emergency response.
{"title":"Ensuring Successful Landslide Investigation During an Emergency Response","authors":"J. D. Graff","doi":"10.2113/EEG-2165","DOIUrl":"https://doi.org/10.2113/EEG-2165","url":null,"abstract":"\u0000 When a destructive landslide happens, geologists may be recruited to be part of the team carrying out the emergency response. An emergency response situation requires geologists to quickly acquire needed geologic information during an intense and stressful assignment. There are five significant operational approaches that are essential to ensure success in this situation. First, the geologists should fully understand and remain focused on the objectives of the response mission. Second, the landslide area must be accessed safely when collecting needed data. From a team standpoint, an injury negatively affects available data and time. Third, the landslide information that is developed must be reliable within the context of the mission and be obtainable within a limited time. Fourth, given the constraints on data collection imposed by an emergency response situation, the degree of uncertainty associated with the findings will need to be explained to ensure subsequent decision-making is done on a sound basis. Fifth, the information needs to be communicated to different audiences, who will range from individual team members to groups of people affected by the landslide. Whether providing documentation or making a presentation, the geologist will need to engage them by explaining the landslide information so it speaks to their needs. Experience gained serving on teams for a huge landslide damming a river in Dominica, West Indies, in 1997 and a large rock slide that buried a major highway in California in 2006 illustrate these important aspects for ensuring success when investigating landslides during an emergency response.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129642585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. R. Oluremi, A. Eberemu, Stephen T. Ijimdiya, K. Osinubi
Inherent variability in engineering properties of lateritic soil in relation to its plasticity, permeability, strength, workability, and natural moisture content, has made it an unpredictable material for use in civil engineering works, resulting in the need for its treatment by stabilization. A lateritic soil classified as A-6(6) and CL, according to American Association of State Highway and Transportation Officials and Unified Soil Classification System of ASTM (2011), was treated with up to 10 percent waste wood ash (WWA). Compaction was carried out using four energies, namely, reduced British Standard light, British Standard light (BSL), West African Standard, and British Standard heavy, on samples, which were then examined for hydraulic conductivity, volumetric shrinkage, and unconfined compressive strength as major criteria for use as liner and for the development of acceptable zones. Specimens with 4 percent WWA content compacted with a minimum BSL energy satisfied the maximum hydraulic conductivity (k) value of 1 × 10−9 m/s, maximum volumetric shrinkage strain of 4 percent, and minimum unconfined compressive strength value of 200 kN/m2 required for use as liner in engineered landfills. The overall acceptable zone was enlarged for up to 4 percent WWA content, thereby accommodating higher moulding water content, but the minimum compactive effort required to achieve it became reduced. The beneficial treatment of lateritic soil with up to 4 percent WWA will perform satisfactorily as liner and covers in waste containment application and will minimize the pollution and environmental impact of wood waste disposal.
{"title":"Lateritic Soil Treated with Waste Wood Ash As Liner in Landfill Construction","authors":"J. R. Oluremi, A. Eberemu, Stephen T. Ijimdiya, K. Osinubi","doi":"10.2113/EEG-2023","DOIUrl":"https://doi.org/10.2113/EEG-2023","url":null,"abstract":"Inherent variability in engineering properties of lateritic soil in relation to its plasticity, permeability, strength, workability, and natural moisture content, has made it an unpredictable material for use in civil engineering works, resulting in the need for its treatment by stabilization. A lateritic soil classified as A-6(6) and CL, according to American Association of State Highway and Transportation Officials and Unified Soil Classification System of ASTM (2011), was treated with up to 10 percent waste wood ash (WWA). Compaction was carried out using four energies, namely, reduced British Standard light, British Standard light (BSL), West African Standard, and British Standard heavy, on samples, which were then examined for hydraulic conductivity, volumetric shrinkage, and unconfined compressive strength as major criteria for use as liner and for the development of acceptable zones. Specimens with 4 percent WWA content compacted with a minimum BSL energy satisfied the maximum hydraulic conductivity (k) value of 1 × 10−9 m/s, maximum volumetric shrinkage strain of 4 percent, and minimum unconfined compressive strength value of 200 kN/m2 required for use as liner in engineered landfills. The overall acceptable zone was enlarged for up to 4 percent WWA content, thereby accommodating higher moulding water content, but the minimum compactive effort required to achieve it became reduced. The beneficial treatment of lateritic soil with up to 4 percent WWA will perform satisfactorily as liner and covers in waste containment application and will minimize the pollution and environmental impact of wood waste disposal.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114151007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Total contents of 36 potentially toxic elements are summarized for agricultural topsoil (n = 12; soil depth = 0–20 cm), subsoil (n = 12; soil depth = 20–40 cm), and representative rock samples collected from a Mediterranean site (Megara Plain, Greece). The five-stage sequential extraction procedure for the geochemical partitioning of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), and nickel (Ni), proposed by Tessier, was applied to topsoil and subsoil collected from the study area. Soil Cd was highly associated with exchangeable fraction, illustrating high bioavailability of this element. The order of mobility of the elements was as follows: Cd > Cu > Co > Zn > Ni > Cr > Mn. Results from sequential extraction experiments illustrated that the bioavailability of Cu, Co, and Zn is moderate, while Ni, Cr, and Mn presented low bioavailability, indicating that these elements could pose a limited threat to the quality of crops. Cadmium is the chief contamination controlling factor posing moderate potential ecological risk. The contamination sources of the examined elements are discussed.
总结了农业表层土壤中36种潜在有毒元素的总含量(n = 12;土深= 0-20 cm)，底土(n = 12;土壤深度= 20-40 cm)，以及从地中海遗址(希腊Megara平原)收集的代表性岩石样本。Tessier提出的镉(Cd)、钴(Co)、铬(Cr)、铜(Cu)、锰(Mn)和镍(Ni)地球化学分配的五阶段顺序提取方法应用于研究区收集的表土和底土。土壤镉与可交换分数密切相关，表明该元素具有较高的生物利用度。元素的迁移率顺序为:Cd > Cu > Co > Zn > Ni > Cr > Mn。连续提取实验结果表明，Cu、Co和Zn的生物利用度中等，而Ni、Cr和Mn的生物利用度较低，表明这些元素对作物品质的威胁有限。镉是主要污染控制因子，具有中等的潜在生态风险。讨论了被测元素的污染源。
{"title":"Environmental Availability of Potentially Toxic Elements in an Agricultural Mediterranean Site","authors":"D. Alexakis, D. Gamvroula, Eleni Theofili","doi":"10.2113/EEG-2129","DOIUrl":"https://doi.org/10.2113/EEG-2129","url":null,"abstract":"\u0000 Total contents of 36 potentially toxic elements are summarized for agricultural topsoil (n = 12; soil depth = 0–20 cm), subsoil (n = 12; soil depth = 20–40 cm), and representative rock samples collected from a Mediterranean site (Megara Plain, Greece). The five-stage sequential extraction procedure for the geochemical partitioning of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), and nickel (Ni), proposed by Tessier, was applied to topsoil and subsoil collected from the study area. Soil Cd was highly associated with exchangeable fraction, illustrating high bioavailability of this element. The order of mobility of the elements was as follows: Cd > Cu > Co > Zn > Ni > Cr > Mn. Results from sequential extraction experiments illustrated that the bioavailability of Cu, Co, and Zn is moderate, while Ni, Cr, and Mn presented low bioavailability, indicating that these elements could pose a limited threat to the quality of crops. Cadmium is the chief contamination controlling factor posing moderate potential ecological risk. The contamination sources of the examined elements are discussed.","PeriodicalId":138906,"journal":{"name":"Environmental and Engineering Geoscience","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134522020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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