Hydrochemistry and Classification of Groundwater Resources of Ishwardi Municipal Area,Pabna District,Bangladesh

The chemical property of groundwater depends largely on the mineralogical composition of the rocks through which the water has moved and the rate of movement and these characteristics of surface water depend on organic and inorganic reactions, industrial effluents, rainfall and temperature etc. The underground water tends to contain more dissolved materials than those in surface water because of their more intimate and longer contact with organic materials of soil and rock particles. The groundwater of the studied area is dominant of alkaline earth’s (Ca²⁺ and Mg²⁺) and weak acids (HCO₃ ⁻) which may be classified as Magnesium-Bicarbonate and Calcium Carbonate types. Genetically, the groundwater of the area belongs to both “Normal Chloride” “Normal Sulphate” and “Normal Carbonate” to “Super Carbonate” group. Based on EC, SAR and RC, the groundwater of the area varies from good–excellent quality for irrigation purposes with low alkali hazard and medium salinity hazard.     

Use of remote sensing data in comprehending an extremely unusual flooding event over southwest Bangladesh

Natural Hazards - Flooding is one of the natural disasters that affect the livelihood of the people living in the floodplains, like Bangladesh. Here, we proposed to employ SAR satellite images in...     

A Methodology for Clustering Lakes in Alberta on the basis of Water Quality Parameters

In this study, a methodology for clustering 18 lakes in Alberta, Canada using the data of 19 water quality parameters for a period of 11 years (1988–2002) is presented. The methods consist of (i) principal component analysis (PCA) to determine the dominant water quality parameters, (ii) cluster analysis techniques to develop the characteristics of the clusters, and (iii) pattern‐match lakes to determine the appropriate cluster for each of the lakes. The PCA revealed that three principal components (PCs) were able to explain ～88% of the variability and the dominant water quality parameters were total dissolved solids, total phosphorus, and chlorophyll‐a. We obtained five clusters for the period 1994–1997 by using the dominant parameters with water quality deteriorating as the cluster number increased from 1 to 5. Upon matching cluster patterns with the entire dataset, it was observed that some of the lakes belonged to the same cluster all the time (e.g., cluster 1 for lakes Elkwater, Gregg, and Jarvis; cluster 3 for Sturgeon; cluster 4 for Moonshine; and cluster 5 for Saskatoon), while others changed with time. This methodology could be applied in other regions of the world to identify the most suitable source waters and prioritize their management. It could be helpful to analyze the natural controlling processes, pollution types, impact of seasonal changes and overall quality of source waters. This methodology could be used for monitoring water bodies in a cost effective and efficient way by sampling only less number of dominant parameters instead of using a large set of parameters.     

Foundation design considerations for a pile supported critical facility

A large reinforced concrete structure supported on piles extending to bedrock is evaluated using a seismic soil–structure interaction analysis. The physical structure, the supporting pile system, analysis model and analytical methodology used are described. Important considerations in the design of the foundation pile system using the seismic analysis loadings and deformations are discussed.     

Experimental (clay) models of inversion structures

Experimental modeling is used to study the geometry and evolution of inversion structures. Two main types of inversion structures are analyzed:

1. (1) structures formed by fault-propagation folding; and

2. (2) structures formed by fault-bend folding on listric faults.

Fault-propagation inversion structures initially develop as broad drape folds with possible fault breakthrough during an early extensional phase. Syn-extensional strata deposited in the hanging wall typically thicken away from the fault. Compressional reactivation results in reversal of slip on the master and secondary faults, their rotation to shallower dips, and the development of a compressional fault-propagation fold. Key features of the fault-propagation fold are basinward thickening of syn-extensional units and resulting steep dips of the front limb of the structure. Fault-bend inversion structures initiate as rollover folds within extensional half-graben. Deformation is primarily localized along a system of antithetic faults. Syn-extensional strata typically thicken across the fault but also thin basinward away from the fault. During compression, the extensional rollover folds are folded into compressional fault-bend folds. Key features of this structure are thinning of syn-extensional units into the basin. Inversion of more symmetric graben results in a doubly-convex geometry of syn-extensional units. These observations of bed geometry and thickness provide predictive models for interpreting the geometries of inversion structures in areas of poor data quality.     

Effect of soil aging on arsenic fractionation and bioaccessibility in inorganic arsenical pesticide contaminated soils

Ingestion of As – contaminated soil by children is a growing concern in former agricultural lands converted to residential or recreational land use areas. The mobility and bioavailability of As is controlled by its reactions with soil particles. The degree and strength of As retention by soil constituents may vary greatly with time. The present authors hypothesize that aging results in reduced mobility of As thereby decreasing As release and its bioavailability. The present study is aimed at evaluating the effect of aging on soil As fractionation and bioaccessibility in a temperature and humidity-controlled greenhouse setting. The design allowed the evaluation of dynamic interactions between soils, pesticides, water, and plants. Therefore, 4 soil types (Immokalee, Millhopper, Pahokee Muck, and Orelia) were selected based on their potential differences in As reactivity. The soils were amended with the pesticide Na arsenate at two rates. Rice was used as the test crop. Soil samples collected after different time periods (0, 6 months, 1 a and 3 a) were extracted for soil-As forms via a sequential extraction technique. Bioaccessible As was extracted via an in vitro gastrointestinal method. At time 0, most of the extractable As in soil was in the soluble form, resulting in high bioaccessibility. As expected, soluble and exchangeable fractions decreased with time for up to 6 months, but remained constant thereafter. After 3 a of soil–pesticide equilibration, As bioaccessibility was still high in all the soils except for the Pahokee Muck. No significant difference in As bioaccessibility was observed between the soils. Arsenic was present predominantly as As(V) with 5–10% of the total dissolved As being present as As(III). Data obtained suggest that although aging had an impact on the geochemical forms, gastric pH was the sole important factor effecting As bioaccessibility.     

Compositional variations,chemical weathering,and provenance of sands from the Cox’s Bazar and Kuakata beach areas,Bangladesh

The modal and chemical composition of sands from Cox’s Bazar beach (CBB) and Kuakata beach (KB) areas of Bangladesh has been investigated to infer their maturity, chemical weathering, and provenance signatures. The CBB and KB sands are typically high quartz, low feldspar, and lithic fragments, representing a recycled orogen source. Major element compositions of CBB sands are characterized by high SiO₂ (83.52–89.84 wt%) and low Al₂O₃ (4.39–6.39 wt%), whereas KB sands contained relatively low SiO₂ (63.28–79.14 wt%) and high Al₂O₃ (9.00–11.33 wt%) contents. The major, trace and rare earth element (REE) compositions of beach sands display comparable distribution patterns with enriched Th and SiO₂ for both sands relative to upper continental crust (UCC). Pb, Rb, Y, and Fe for KB sands are little higher than UCC and the rest of the elements are marked depleted for both suites reflecting destruction of plagioclase and K-feldspar during fluvial transportation. The CBB and KB sands are compositionally low mature to immature in nature subsequently classified as subarkose and litharenite, respectively. Chondrite-normalized REE patterns for CBB and KB sands show LREE enrichment and nearly flat HREE (La_N/Yb_N, 7.64–9.38 and 5.48–8.82, respectively) coupled with prominent Eu anomalies (Eu/Eu*, 0.51–0.72 and 0.52–0.76, respectively), suggesting felsic source provenance. The provenance discrimination diagrams, immobile trace element ratios (Th/Sc, Zr/Sc, Ce/Sc, and Ti/Zr), and REE (∑LREE/HREE, Eu/Eu* and Gd_N/Yb_N) parameters indicate that CBB and KB sands were largely derived from felsic source rocks, with compositions close to average rhyolite, granodiorite, granite, and UCC.