Geo-environmental Conditions Research Articles

A Comparative Study of Kernel Logistic Regression, Radial Basis Function Classifier, Multinomial Naïve Bayes, and Logistic Model Tree for Flash Flood Susceptibility Mapping

Risk of flash floods is currently an important problem in many parts of Vietnam. In this study, we used four machine-learning methods, namely Kernel Logistic Regression (KLR), Radial Basis Function Classifier (RBFC), Multinomial Naïve Bayes (NBM), and Logistic Model Tree (LMT) to generate flash flood susceptibility maps at the minor part of Nghe An province of the Center region (Vietnam) where recurrent flood problems are being experienced. Performance of these four methods was evaluated to select the best method for flash flood susceptibility mapping. In the model studies, ten flash flood conditioning factors, namely soil, slope, curvature, river density, flow direction, distance from rivers, elevation, aspect, land use, and geology, were chosen based on topography and geo-environmental conditions of the site. For the validation of models, the area under Receiver Operating Characteristic (ROC), Area Under Curve (AUC), and various statistical indices were used. The results indicated that performance of all the models is good for generating flash flood susceptibility maps (AUC = 0.983–0.988). However, performance of LMT model is the best among the four methods (LMT: AUC = 0.988; KLR: AUC = 0.985; RBFC: AUC = 0.984; and NBM: AUC = 0.983). The present study would be useful for the construction of accurate flash flood susceptibility maps with the objectives of identifying flood-susceptible areas/zones for proper flash flood risk management.

Sustenance of Seed Germination Potential of Two Okra (<em>Abelmoschus esculentus</em> L. Moench) Varieties under Different Environmental Conditions in Sri Lanka

Okra (Abelmoschus esculentus L. Moench) is a popular vegetable grown in most parts of Sri Lanka. Farmers and home gardeners purchase seeds in packed-form from retail outlets. However, quality problems are frequently reported, especially claiming low field germination even with the laboratory-tested and certified seeds. Quality parameters namely, percentage germination, moisture, field emergence and vigour index analysis were used to determine the effect of different storage environmental conditions on seed longevity of two okra varieties during a two-year storage period, from March 2016 to March 2018. Seeds in triple-laminated packets stored in four contrasting environments, namely, low temperature storage conditions (17°C and 60-65% RH); three geoenvironmental conditions namely; Gannoruwa (Mid Country Wet Zone), Kundasale (Mid Country Intermediate Zone), and MahaIlluppallama (Low Country Dry Zone) displayed varied behavior in seed quality parameters respective of the variety. It was apparent that germination test alone does not represent the full potential of field emergence. Results of the present study revealed that when field emergence and vigour are also taken in to account, both varieties of okra seed (with initial germination and moisture of ca. 94% and ca. 10%) can be stored under ambient conditions at Gannoruwa, Kundasale or MahaIlluppallama for a maximum period of 12 months, without compromising the seed quality. The seeds stored under low temperature conditions (i.e. 17°C), maintained the seed germination over 75% for a period of 24 months.

Generating Substantially Complete Landslide Inventory using Multiple Data Sources: A Case Study in Northwest Himalayas, India

Abstract Landslide inventory contains basic information about landslides such as location, classification, morphometry, volume, run-out distance, activity, date of occurrence, damages caused etc. In most landslide inventory maps only spatio-temporal distribution of slope failures is shown. A complete portrayal of landslide inventory, both in number of landslides mapped and associated attributes such as morphometry, classification etc. is a must as it has bearing on the estimation of landslide susceptibility, hazard and risk. Despite of its enormous importance, landslide inventory is rarely found to be complete. This can be attributed to limited availability of requisite data and the inherent uncertainties in landslide inventory mapping from different sources and importantly the insufficient field inputs. In the present work in the Mandakini valley of Uttarakhand Himalayas attempts have been made to prepare a substantially complete landslide inventory, both in terms of number of landslides and attributes, using multifarious data sources substantiated with thorough field checks. Supplementary historical data sources along with the conventional data sources have been used to prepare the inventory. The approach followed includes pre-field mapping of landslides from different Earth Observation (EO) data followed by interpretation of archival records and detailed field surveys. The data available for the period 1962 to 2013 were used to build up the inventory database in GIS. A total of 644 landslides have been mapped and attributed using conventional EO data and also the different supplementary data sources for an area covering 400 sq. km. An inventory of 151 landslides prepared from EO data have been confirmed and updated during the field study. Finally, the detailed landslide inventory prepared during the course of this study was analysed to understand the behaviour of landslides and role of triggering factors in susceptibility mapping and the geo-environmental conditions governing the magnitude of the event.

The Impact of Biosolids on the Geotechnical Properties of Some Soils of the Niger Delta Sub-region, Nigeria

The production of biosolids (human wastes) in the Niger Delta of Nigeria has been taking place since man inhabited the sub-region. One of the negative impacts of <i>biosolids</i> is the changes to the geo-environmental conditions of the soils of the sub-region. Studies carried out on the effects of biosolids in the Niger Delta Sub-region over the last sixteen years indicate that the conventional geo-environmental engineering properties of the soils have been altered significantly. Biosolids have been found to affect both the grain size distribution patterns, the Atterberg Limits (Liquid Limits (LL), Plasticity indices (PI), California Bearing Rations (CBRs), Proctor Compaction indices such as Maximum Dry Densities (MDD); Optimum Moisture Contents (OMC), Soil friction angles () & cohesion values (c) and to an extent Ultimate Bearing Capacities (ϥ_ult. & ϥ_allow). Biosolids applied on two types of tropical soils classified as slightly to medium plastic (lateritic (CL) and Sandy (SP) soils) batched and mixed at four different percentage levels of 5%, 10%, 15% and 20% by weight of sample indicated that % biosolids in the soils positively correlated with the Total Organic Contents (TOC) while inversely correlating with the Moisture content in the lateritic soils to a limiting value at 15%, while in the basically sandy soil it was at the 20% biosolids treatment. The infiltration rate increased to a peak at 13.5% biosolids content and thereafter decreased, while in the basically sandy soil, addition of biosolids caused the infiltration rate to fluctuate. It has also been observed that 100kN is the critical stress under which high volume reduction is recorded in all cases of biosolids treatments. The 5 to 10% biosolids treatment range experienced minimum volume change (∆v) compared to the 15 to 20% biosolids treatment range. The wide gap observed existing between 15 – 20% and 0 – 10% biosolids treatment ranges tends to suggest the existence of two groups of biosolids-treated lateritic soils namely: the Low and High Compressible Lateritic soils.

GEOECOLOGICAL FEATURES OF SOLID MUNICIPAL WASTE STORAGE FACILITIES PLACEMENT IN VORONEZH REGION

The article discusses the geo-environmental conditions of Voronezh region, which have a significant impact on potential environmental threat of solid municipal waste (MSW) facilities. Zoning of the region was carried out according to the priority of potentially dangerous geoecological factors to be assessed when choosing the location of MSW landfills. Conclusions made in this work can serve as recommendations in formation of a resource-saving environmentally friendly waste management system in the territory of the Voronezh region.

A (des)proteção do solo em Goiás: um estudo de caso da microrregião de Quirinópolis – GO

A partir da década de 70 se inicia no estado de Goiás um processo de intensificação da expansão da fronteira agrícola estimulada por políticas governamentais. A entrada da cana-de-açúcar no estado se relaciona às condições geoambientais favoráveis para o seu cultivo, destacando-se a mesorregião sul de Goiás como a mais importante região produtora do estado na qual está inserida, dentre outras, a microrregião de Quirinópolis. Diante desse cenário, o presente artigo buscou analisar a discrepância entre o uso da terra e capacidade de uso dessa região no período entre 2004 e 2010, contrapondo o resultado obtido à legislação vigente à época analisada. A realização deste estudo, comparando os dados apurados antes e depois da entrada da cana-de-açúcar, permitiu identificar a abrupta expansão da cana e a inaptidão do solo da microrregião para o cultivo dessa cultura, especialmente em razão da utilização de processos altamente tecnificados, os quais resultam em previsíveis impactos ambientais. Ao se analisar esses resultados em paralelo à legislação vigente à época, pode-se perceber o descompasso entre a previsão legal e a efetiva proteção do solo, principalmente em razão da ausência de leis específicas voltadas para a proteção desse recurso natural e da maneira rasa como o solo é considerado nas demais leis estudadas.

Predicting Weathering Characteristics of Carbonate Rocks Under Different Geo-Environmental Conditions

Rock moisture content, temperature and physical and chemical conditions of water in the rock mass vary under different geoenvironmental conditions. These factors are critical in the mechanical and chemical disintegration of rocks with time. Changes in weathering characteristics of a rock mass correlate with major changes in shear strength and deformability of rocks. Therefore, durability is an important parameter for rocks and weathered rocks in predicting and assessing long term problems in their use for engineering purposes. Carbonate rocks are generally considered as durable strong rocks. It is important to test this claim in the UAE, where carbonate rocks are the main available rock materials in many locations e.g. in Al Ain city. The slake durability index (SDI), with tests involving several cycles of wetting and drying, is widely recognized and has been used to measure the durability of weathered rocks. Carbonate rocks in the Jabel Hafit mountain, Al Ain region, have highly fractured and cavernous surface and near surface structures. In this study, degradability of samples from three different carbonate sequences: the Rus, Dammam, and Asmari Formations, were studied petrographically, mineralogically and texturally before and after slaking. A number of slaking tests were performed on twenty-one rock samples, seven from each rock formation, in order to investigate the effects of various geoenvironmental conditions on carbonate rocks weatherability at various pH levels 2, 4, 6, 8, 10, 12 and 14. Detailed mineralogical examinations, rock thin sections, Scanning Electronic Microscope (SEM) and X-ray diffractometry (XRD) were employed to reveal the relationship between mineralogy and weathering characteristics of rocks on the representative rock samples, before and after the slake durability tests. Furthermore, the index properties of all samples such as unit weights (dry, γd and saturated, γsat), the water absorption (Wa), the porosity (n), void ratio (e) and the specific gravities (GS,(OD), GS,(SSD), GS,(A)) were measured. The study reveals that the weathering characteristics of carbonate rocks under different geoenvironmental conditions is strongly controlled by the mineralogical composition and textural features of the rocks. The impact of slaking fluid in the degradability of limestone is very limited due to chemical reaction of CaCO3 especially in lower pH level acidic fluid, which reduced the bonding strength between grains. The findings will certainly help to resolve durability problems associated with engineering applications such as tunnels, slope stability, and etc. in the region and elsewhere.

Road widening along National Highway-58, Uttarakhand, India

In the perilous Himalayan region, the roadway network serves as arteries for transportation. The terrain is susceptible to potential landslides due to its inherent geology which is reflected in its weak rocks. Anthropogenic intervention for developmental activities is continuously aggravating and deteriorating the geoenvironmental condition of the region. One such intervention is the widening of roads being performed on fragile slopes. Here, the issues pertaining to improper excavation for road widening along National Highway- 58, Uttarakhand, India have been discussed. The surface and subsurface drainage treatment is the foremost measure that needs to be undertaken. Excavation at steep angle should be avoided. Some preventive measures like steel mesh should be used to retain potential falling blocks along with flexible barriers to reduce kinetic energy of these blocks. Proper execution of remedial measures will strengthen the safety along the highway. The excavated muck should be dumped by constructing well-planned and scientific dumping sites. Rock shed construction is proposed for rockfall-prone sections.

PUBLIC POLICY ANALYSIS ON DISASTER THREAT DUE TO GEO-ENVIRONMENTAL CONDITION OF TUGURARA RIVER IN TERNATE CITY, NORTH MALUKU PROVINCE

This research was conducted to produce a public policy model to anticipate floods in Ternate City due to changes in the geo-environmental conditions of the Tugurara River based on geological analysis results. These model intended to help the local government in determining the policy to deal with the Tugurara River disaster threat. Analysis of geo-environmental conditions was conducted using statistical methods obtained from previous studies - furthermore, the theory of public policy analysis in determining the appropriate policy for handling the risk that will occur. Results revealed that runoff water correlates with extensive changes of the Tugurara River area. These area change becomes more because of runoff water discharge amount erode the rock on the river wall and cause the river wall as well as the presenting any material river wall along the river as a catastrophic outburst flood lava on a residential area three villages in 2011 (this condition is particular compare than another river in North Maluku or others). Therefore changes Tugurara River area, occurred very significant. The river engineering can refer to the flood prevention model that has been applied to the Jeneberang River in South Sulawesi by building Sabo Dam along the river, adapted to the particular characteristics of the Tugurara River. Therefore, the critical formulation of public policy alternative carried out by the Ternate City government is infrastructure development, community involvement, and networking development. After the public policy is determined, then further research can be conduct on the evaluation and comprehensive analysis of policy implementation.

Demands on land: Mapping competing societal expectations for the functionality of agricultural soils in Europe

The Common Agricultural Policy (CAP) of the European Union (EU) has been highly successful in securing the supply of food from Europe’s agricultural land. However, new expectations have emerged from society on the functions that agricultural land should deliver, including the expectations that land should regulate and purify water, should sequester carbon to contribute to the mitigation of climate change, should provide a home for biodiversity and allow for the sustainable cycling of nutrients in animal and human waste streams. Through a series of reforms of the CAP, these expectations, or ‘societal demands’ have translated into a myriad of EU and national level policies aimed at safeguarding the sustainability and multifunctionality of European agriculture, resulting in a highly complex regulatory environment for land managers. The current reform of the CAP aims to simultaneously simplify and strengthen policy making on environmental protection and climate action, through the development of Strategic Plans at national level, which allow for more targeted and context-specific policy formation. In this paper, we contribute to the knowledge base underpinning the development of these Strategic Plans by mapping the variation in the societal demands for soil functions across EU Member States, based on an extensive review of the existing policy environment relating to sustainable and multifunctional land management. We show that the societal demands for primary production, water regulation and purification, carbon sequestration, biodiversity and nutrient cycling vary greatly between Member States, as determined by population, farming systems and livestock densities, geo-environmental conditions and landscape configuration. Moreover, the total societal demands for multifunctionality differs between Member States, with the lowest demands found in Member States that have designated the higher shares of EU CAP funding towards ‘Pillar 2′ expenditure, aimed at environmental protection and regional development. We review which lessons can be learnt from these observations, in the context of the proposals for the new CAP for the period 2021–2027, which include enhanced conditionality of direct income support for farmers and the instigation of eco-schemes in Pillar 1, in addition to Agri-Environmental and Climate Measures in Pillar 2. We conclude that the devolution of planning to Strategic Plans at national level provides an opportunity for more effective and targeted incentivisation of sustainable land management, provided that these plans take account for variations in the societal demand for soil functions, as well as the capacity of contrasting soils to deliver on this multifunctionality.

Groundwater quality assessment using water quality index with a special focus on vulnerable tribal region of Eastern Ghats hard rock terrain, Southern India

Hydrochemical characteristics of groundwater in the vulnerable tribal region of Gosthani river basin extended in Eastern Ghats hard rock terrain, Andhra Pradesh state, Southern India were determined. The occurrence of groundwater in hard rock terrain of this region is predominantly controlled by joints, fractures, porosity, and thickness of the weathered zone. The geoenvironmental conditions within aquifer are influencing the occurrence and concentration of chemical parameters of groundwater. In order to evaluate the quality of groundwater in the area, 24 groundwater samples were collected and analyzed for various physicochemical parameters such as pH, EC, TDS, TA, TH, Ca2+, Na+, K+, Fe, SO42−, NO3−, Cl−, and F−. Mg2+, HCO3− plus CO32−, Gibbs ratios, CAI, %Na, SAR, RSC, PI, KR, and CR were computed. The results revealed that the groundwater in the area is soft to hard water type. The abundance of the major cations are Ca2+>Na+>Mg2+ and major anions are HCO3−>Cl−>NO3−. The dominant hydrochemical facies of groundwater is Ca-Na-HCO3 and Ca-HCO3-Cl type. In the study area, the vulnerable tribal population lives in remote and inaccessible areas and is mainly dependent on groundwater for drinking and other purposes. The result of low concentrations of various chemical ions in the water suggested that less enrichment of mineral content caused various health hazards in the indigenous tribal population. Soil erosion, deforestation, and traditional shifting cultivation activities are encouraging for improper leaching of chemical constituents into the groundwater. Further, the high levels of iron found in 87.5% of samples are possibly by the source rock interaction with water. Overall, the assessment of water quality using WQIA and other methods indicates that some samples in the study region are chemically unsuitable for drinking and irrigation purposes. The present work provides baseline information in solving problems due to quality deterioration of the groundwater for implementing sustainable management practices in improving the living conditions of the tribes of this region.

Applying population-based evolutionary algorithms and a neuro-fuzzy system for modeling landslide susceptibility

The main objective of the present study was to produce a novel ensemble data mining technique that involves an adaptive neuro-fuzzy inference system (ANFIS) optimized by Shuffled Frog Leaping Algorithm (SFLA) and Particle Swarm Optimization (PSO) for spatial modeling of landslide susceptibility. Step-wise Assessment Ratio Analysis (SWARA) was utilized for the evaluation of the relation between landslides and landslide-related factors providing ANFIS with the necessary weighting values. The developed methods were applied in Langao County, Shaanxi Province, China. Eighteen factors were selected based on the experience gained from studying landslide phenomena, the local geo-environmental conditions as well as the availability of data, namely; elevation, slope aspect, slope angle, profile curvature, plan curvature, sediment transport index, stream power index, topographic wetness index, land use, normalized difference vegetation index, rainfall, lithology, distance to faults, fault density, distance to roads, road density, distance to rivers and river density. A total of 288 landslides were identified after analyzing previous technical surveys, airborne imagery and conducting field surveys. Also, 288 non-landslide areas were identified with the usage of Google Earth imagery and the analysis of a digital elevation model. The two datasets were merged and later divided into two subsets, training and testing, based on a random selection scheme. The produced landslide susceptibility maps were evaluated by the receiving operating characteristic and the area under the success and predictive rate curves (AUC). The results showed that AUC based on the training and testing dataset was similar and equal to 0.89. However, the processing time during the training and implementation phase was considerable different. SWARA-ANFIS-PSO appeared six times faster in respect to the processing time achieved by SWARA-ANFIS-SFLA. The proposed novel approach, which combines expert knowledge, neuro-fuzzy inference systems and evolutionary algorithms, can be applied for land use planning and spatial modeling of landslide susceptibility.

Numerical investigation of particle shape on mechanical behaviour of unsaturated granular soils using elliptical particles

The unsaturated soils mechanic is of significant importance for understanding and predicting the actual behavior of unsaturated soils in plenty of geo-environmental condition including tailing dams and earth dams during construction and operation, soil slopes, and shallow foundations. In this research, a micromechanical model for unsaturated assemblies composed of elliptical particles is presented so that the effect of capillary force, confining stress, and particle shape on unsaturated granular media behavior is analyzed in the pendular regime. As one of the early attempts, the toroidal liquid bridge for elliptical particles is studied in granular assemblies using modified ELLIPSE program, Discrete Element Method based program. The results show that although the strength of spherical particles grows when the saturated degree increases, the strength of elliptical particles rises and then decreases; however, the friction angle remains almost constant. Furthermore, the highest percentage of apparent-cohesion rise takes place at saturation degree of 10% at the highest eccentricity. As long as the eccentricity increases, the effect of capillary force on shear strength grows continuously. Not only do unsaturated assemblies contract more at low strains, but also they expand more after the phase transfer point at high stains. The assembly composed of particles with eccentricity of 0.15 has the highest coordination number. The coordination number constantly increases with the saturation degree for circular particles. In contrast, for elliptical particles assemblies, when degree of saturation increases, the coordination number increases at the beginning then drops.

Classification Evaluation of Loess Slope Stability Based on the Combination Weight of Game Theory

Rational classification evaluation of loess slope stability has a guiding significance on the prevention and control of geological hazards. The key of classification evaluation of loess slope stability is to construct evaluation indices system and determine the indices weights, which can be obtained through various approaches currently. Therefore, according to the characteristics of slope hazards and geo-environmental conditions of Mizhi County, the evaluation indices system was constructed by six indices, namely, slope shape, slope gradient, slope height, types of geomorphic unit, lithology and average annual precipitation. And based on the thought of game theory, the combination weights of indices were figured out by different expert weights. Taking the loess slope located at Xinchengqu Village as an example, stability classification of the loess slope was analyzed using the methods mentioned above, and the main results showed that stability classification of the loess slope was unstable whether before sliding or after sliding.

Adaptation of Sustainable Community to the Site's Natural Condition

A common practice in some of North Americans' residential development is to alter the site's natural conditions prior to and during construction. Rock formations are removed or changed, new terrain grading created, and landscape features uprooted. An approach whereby the design will be made to fit the site's characteristics is often avoided.Fitting a master plan of a new community to existing geo-environmental conditions was a principal objective in the planning of a 350-dwelling development on a 41-hectare site near Quebec City, in the province of Quebec, Canada. For the densely forested site, the author developed design guidelines that considered the roads' routes, parking areas, foundation, and footprint of each building. A pillar of this approach was to model the design after the terrain's condition by adopting flexible planning strategies.The project, now in advanced stages of construction, have earned many accolades from conservationists and demonstrated that once documentation of the site's natural conditions has taken place, the fitting of design to the site becomes easier to implement.This paper outlines the design challenges, show patterns that were developed specifically for the project and elaborate on the building process and its outcome.

Soil Erosion Susceptibility Mapping with the Application of Logistic Regression and Artificial Neural Network

At present, the multi-criteria-based predictive mapping of geoenvironmental processes is a considerable research concern in the domain of earth sciences. This study aimed to predict the probability of occurrence or nonoccurrence of soil erosion at any given site based on a range of factors active therein. The GPS survey of 412 observation sites recorded the soil erosion status of Purulia district in the state of West Bengal in India. An algorithm of binary logistic regression and the artificial neural network was used to build an erosion susceptibility model by using 70% dataset of the sample sites. The model performance was assessed with the remaining 30% of the datasets. After a successful validation, the model equation was used to prepare a susceptibility map for the study area. The model was found to be valid for the given study area; however, it can be used for preparing the susceptibility map of water-induced soil erosion at any other area with similar geoenvironmental conditions. The map will help in framing the comprehensive policies for scientific land-use planning and area-specific soil conservation practices. In addition, the susceptibility map may be used as a base map for designing income, employment, and livelihood planning for the agro-based areas and serves as a decision support to the priority-based allocation of funds to different micro-level administrative units for government-sponsored schemes related to agriculture, irrigation, and soil and land management.

Effects of topography and soil properties on soil selenium distribution and bioavailability (phosphate extraction): A case study in Yongjia County, China

Selenium (Se) is an essential trace element for humans. In order to investigate how soil Se is influenced by topography and soil properties, we selected Yongjia County, an area with mountainous topography, as a study area. This study used cultivated soil data to comprehensively analyze the effects of topography and soil properties on Se mobility and bioavailability and to identify the key factors influencing Se distribution in the environment. Factors considered in this study were elevation, slope, topographic wetness index, the coefficient of weathering and eluviation, pH, organic matter, and Fe2O3. The concentration of total soil Se (0.382±0.123mgkg−1) was far higher than the background value of soil in China, and 98% of the soil samples were classified as having moderate Se levels (>0.175mgkg−1), indicating Yongjia County is a Se-rich region in China. Phosphate extracted Se accounted for an average of 9% of the total Se and was significantly associated with soil total Se, Fe2O3, pH, and the coefficient of weathering and eluviation. Fe2O3 primarily controlled Se adsorption, fixation, and availability in soil. Under the geo-environmental conditions in the study area, the total Se in the soil increased first and then decreased with increases in elevation, slope, and the topographic wetness index, and the phosphate extracted Se showed similar patterns except for the elevation. The findings showed that topographical attributes and soil physicochemical properties synthetically influenced the distribution and bioavailability of Se in soil.

Assessment of Liquefaction Potential of the Sediments of Chandigarh Area

ABSTRACT Assessment of the liquefaction potential is one of the important aspects for earthquake hazard assessment. Liquefaction in the sediments during earthquake events may cause significant ground deformation, which in turn, may lead to significant structural damages to civil or engineering structures, further leading to loss of life and property. Liquefaction in sediments occurs in specific geological and geoenvironmental conditions under the influence of a certain level of earthquake shaking. In this paper an assessment of the liquefaction potential of the sediments present in and around Chandigarh has been made. The sub-surface disposition and geotechnical properties of the sedimentary units mapped and depth wise probed by drilling 24 shallow boreholes prima facie indicates susceptibility of interlayed sequence to liquefaction. The conditioning factors and geoenvironmental conditions essential for occurrence of liquefaction have been integrated and analysed to determine potential areas for liquefaction around the Union Territory of Chandigarh with respect to different levels of ground acceleration values expected in the area due to earthquake events.

PH dependent leachings of some trace metals and metalloid species from lead smelter slag and their fate in natural geochemical environment

The influence of pH on the leaching behaviours of As, Cd, Cu, Mo, Ni, Pb, Se and Zn from a lead smelter slag was assessed to understand the ground water pollution potential of slag and the toxicity in geo-environmental conditions. Leaching of slag was investigated by using European EN 12457-2 and prEN 14429 leaching tests. The results obtained from prEN 14429 leaching test were used to determine the acid neutralization capacity (ANC) of slag. The pH dependent leaching results were further assessed by considering existing geo-chemical modeling results of similar types of wastes. Results indicate that the concentrations of some toxic metal and metalloid species in the leachate are higher than their specified limits prescribed for safe landfill disposal as inert or non-reactive hazardous solid waste as well as for safe disposal of effluent in inland surface water. The ANC values obtained for slag at pH values 7, 5 and 4 are 0.75 meqv/g, 3.72 meqv/g and 37.30 meqv/g respectively. The low ANC values as well as the high concentrations of majority of the toxic elements in leachates especially at the pH range of 5–7 indicate hazardous nature of slag for disposal under open atmosphere. The leaching behaviours of iron and calcium under varying pH conditions have profound effect on the pH dependent mobilities of most of the trace elements present in the slag. The sodium, potassium and chloride leaching from slag particularly in the pH range of 4–12 are pH independent and therefore do not have any effect on the mobilities of toxic elements.

Input of geophysics to understand hydrogeology towards the assessment of geoenvironmental conditions in Beira city, Mozambique

As the fourth largest city in Mozambique, and located right beside the Indian Ocean, Beira faces sanitary and environmental problems that are a strong concern to the local and national authorities. One of the major problems that Beira city has to deal with is the existence of undrinkable groundwater in many dug-wells that supply a large amount of the city population. The cooperation project among Direccao Nacional de Geologia of Mozambique, the Laboratorio Nacional de Energia e Geologia of Portugal and the Instituto de Apoio ao Desenvolvimento Portugues that took place from 2007 to 2011 has as one of its main goals the production of the Geological and Geoenvironmental Maps of Beira at scale 1:50,000, intending to create a tool to support the implementation of governmental policies regarding sustainable groundwater and natural resources exploitations, land management and environmental protection. These goals were achieved through the identification, characterization and mapping of the different geological units and the evaluation of the city environmental problems regarding water and soil contamination in urban areas, involving the use of several methodologies that were subsequently integrated and jointly interpreted. These comprised remote sensing techniques, hydrogeology analysis and evaluation and the use of geochemistry and electrical geophysical methods. This work emphasizes the input of geophysical and hydrogeological methods to assess the geoenvironmental conditions of Beira, namely those related with the prediction of occurrence of saline and brackish water in the shallow dug-wells that supply a large amount of Beira populations, especially in the crowded suburbs. Several geophysical surveys using electrical and electromagnetic methods were conducted and interpreted regarding the evaluation of the several hypotheses that were stood for this feature. Results are related with hydrogeological conditions and organic and inorganic hydrochemical analysis. Considering these facts, this study was an important input for mapping areas with saline and brackish water imprisoned in the subsurface geological formations, using a wider set of methodologies that were integrated in these results.