TECTONIC AND GEOTECHNICAL REVIEW OF BENGAL BASIN FOR SEISMIC RISK ASSESSMENT IN BANGLADESH

Four major geotectonic provinces of the basin are recognized: 1) the continental slope to the west of the Hinge Zone, 2) the stable shelf, 3) the deep central trough (Sylhet-Hatiya) and 4) the Chittagong-Tripura fold belt to the east. The ~300 km long Dauki Fault demarcates the elevated Shillong Plateau, part of the Indian Shield to the north and the deep basin to the south. The basin experienced three strong to major intraplate earthquakes: a) 1885 Bengal earthquake (rev. Mw 6.8) close to the Hinge Zone, b) 1918 Srimangal earthquake (rev. Mw 7.1) on the Sylhet (trough) fault and c) 1923 Mymensingh earthquake (rev. Mw 7.0) at the northern end of the Hinge Zone where it intersects the Dauki Fault. In addition, Bangladesh also experienced similar tectonic energy release from the Shillong Plateau earthquakes like Great Assam Earthquake (1897, rev. Mw 8.1) and moderately active Indo-Burma subduction zone in the east. Rational assessment for seismic threats is determined by: hypocenter locations, the intensity of local/regional seismicity, differential tectonic stress condition, the geometry of discontinuities, and states of highest energy release. Site effects are evaluated from geophysical and geotechnical investigations. A 3D site-specific seismic hazard characterization of the capital megacity Dhaka is made to assess the seismic risk. It is observed that lateral and vertical discontinuities are subjected to multiple segmentations that facilitate tectonic movements. 1918 Srimangal event of Mw 7.1 is the largest recorded intraplate earthquake. Generation of enough tectonic stress in Bengal basin is very unlikely which might cause megathrust induced earthquakes (Mw 8-9) in Banglades

RECRUITING AND RETAINING K9–16 STUDENTS THROUGH FIELD- AND LABORATORY - BASED GEOSCIENCE EXPERIENCES

Since 2004, we have been directly involved with the GSA to provide access and opportunities for K9-16 students, particularly those interested in the broader aspects of geoscience-related topics, to present their field-and- laboratory based research outcomes at professional conferences and to learn from each other. So far, well-over 400 students from the U. S. and abroad have taken advantage of this opportunity and participated our topical sessions. It is quite gratifying to report that many of these students, as a result of their attendance at the GSA conference, felt a continuing need for exposure to high-level professional venues with effective knowledge-sharing and improving the level of understanding of the presented material. In addition, several presenters enthusiastically acknowledged their satisfaction with the significance of attendance at such high level meetings and potential to improve their chances of professional employment. Potential employers valued their experiential learning skills from both the educational and communications point of view and appreciated their endeavors and the preparation needed to attend and present at GSA conferences. Present-day extreme weather phenomena, environmental degradation, increased mega-flooding event, landslides, access to fresh drinking water, build-up or upgrading of aging infrastructures, etc. are closely tied to geological processes and anthropogenic practices. Students need to observe and connect geoscience concepts and understanding of the various phenomena, including representative case studies, to validate geoscience as a transformative discipline and its interdependence with other STEM disciplines such as physics, chemistry, and biology. We strongly believe that the future geoscience workforce needs to be trained from as early as the K9-12 grades via an integrated earth science curriculum that allows an open access to field-and research based content, creates inquiry-based knowledge, promotes group dynamics, and instills a sense of belonging. Given that over 70,000 K9-12 students took the Earth Science Regents examination last year in New York City alone, it will be worthwhile to work with the new cohort and provide them with a variety of learning tools to engage, inspire and attract them to the future geoscience-related workforce build-up

Retrospective study of surgical cases of ruminants at Veterinary Teaching Hospital, Bangladesh Agricultural University

Objective: A retrospective survey was designed to determine the prevalence and factors involved in surgical cases at the Veterinary Teaching Hospital (VTH), Bangladesh Agricultural University from June 2014 to June 2017. Materials and materials: In total, 1042 surgical cases of food animal (large ruminants: n=564, and small ruminants: n=493) and 26 non-food animal (mono-gastric animal) were recorded from patient register book and case recording card. Data were analyzed by Epi Info TM software and frequencies were calculated for different variables using Statistical Package for Social Science (SPSS) software. Result: In large ruminant, hernia (16.13%) ranked top (90% umbilical and 10% lateral) followed by fracture (14.89%), abscess (14.54%), umbilical myasis (10.46%), atresia ani (5.85%) and naval ill (4.07%). Among the reported cattle, 87.41% were crossbred and 12.59% were indigenous. Calf, heifer and adult cattle were 55.32, 10.29 and 34.39% respectively. In small ruminants, castration (32.94%; n=138) ranked top followed by myasis (10.55%) naval ill (10.31%), abscess (7.44%), dystocia (6.24%) and urolithiasis (5.49%). Based on surgical classification in large and small ruminants, 37.56 and 42.50% were reported for general surgery, whereas 28.71 and 7.15% for congenital, 11.18 and 13.12% for gynecological and 2.65 and 37.23 % for andrological problems, respectively. Male and female ratio was 1:1.31 and 2:1 respectively in large and small ruminants, respectively. Conclusion: This study emphasizes the factors related to successful surgical cases management at VTH. The results may help in controlling surgical related cases in Mymensingh region of Bangladesh. [J Adv Vet Anim Res 2018; 5(1.000): 81-87

Arsenic Contamination in Groundwater of Bangladesh: Perspectives on Geochemical, Microbial and Anthropogenic Issues

A groundwater, sediment and soil chemistry and mineralogical study has been performed to investigate the sources and mobilization process of Arsenic (As) in shallow aquifers of Bangladesh. The groundwater from the shallow aquifers is characterized by high concentrations of Arsenic (47.5–216.8 µg/L), iron (0.85–5.83 mg/L), and phosphate, along with high electrical conductivity (EC). The groundwater has both very low oxidation-reduction potential (Eh) and dissolved oxygen (DO) values indicating reducing conditions. By contrast, the deep aquifers and surface waters (pond, canal) have very low concentrations of Arsenic ( < 6 µg/L), iron (0.12–0.39 mg/L), and phosphate along with a relatively low EC. Furthermore, the values of Eh and DO are high, indicating oxic to suboxic conditions. Arsenic is inversely correlated with Eh values in the upper aquifer, whereas no relationship in the deeper aquifer is observed. These results suggest that As mobilization is clearly linked to the development of reducing conditions. The clayey silt, enriched in Fe, Mn, Al oxides and organic matter, and deposited in the middle unit of shallow aquifers, contains moderately high concentrations of As, whereas the sediments of deep aquifers and silty mud surface soils from paddy fields and ponds contain a low content of As (Daudkandi area). Arsenic is strongly correlated with the concentrations of Fe, Mn and Al oxides in the core samples from the Daudkandi and Marua areas. Arsenic is present in the oxide phase of Fe and Mn, phyllosilicate minerals and in organic matter in sediments. This study suggests that adsorption or precipitation of As-rich Fe oxyhydroxide on the surface or inner sites of biotite might be responsible for As concentrations found in altered biotite minerals by Seddique et al. Microbially or geochemically mediated reductive dissolution of Fe oxyhydroxides is the main mechanism for As release. The reducing conditions are caused by respiratory decomposition of organic matter, either sedimentary or labile organic C. The process can be accelerated by agricultural activity and domestic organic wastes. An agricultural fertilizer can directly contribute As to groundwater as well as promote As mobilization by ion-exchange with phosphorus