ignificant amounts of heavy metals in the directly discharged wastewater released from the newly built tannery industrial site inDhaka,Bangladeshare reported. Despite their detrimental impacts on public health and natural ecosystem, no environmental impact study is yet conducted. Therefore, information on safe discharge rates are not available. In this study, the extent of pollution around the industrial site is investigated for four representative trace metals. Temporal and spatial distributions of chromium (Cr), lead (Pb), cadmium (Cd) and arsenic (As) have been predicted using a numerical model with the aim to estimate safe discharge of these metal contaminants. From multiple simulation runs it has been estimated that a discharge of0.026 m3 of wastewater per day can lead to high levels of Cr and Pb accumulation, exceeding the regulatory standard limits, in the study area. Whilst As and Cd concentrations remain below the advised limits in most cases at this rate. However, an order of magnitude reduction in the total discharge rate, i.e.,0.0026 m3 per day, results into the metal accumulation below the recommended guidelines in all cases. Elevated concentration of Pb is found to be limited to the top 0.5 m of the soil as compared to Cr, As and Cd, which exhibit larger spread along the depth of the soil. The relative dominance of the metal contamination follows the sequence: Pb>Cr>As>Cd as sorbed concentration in soil aggregates and Cr>Pb>As>Cd as aqueous concentration in soil porewater. Further investigations that are essential for a comprehensive environmental impact assessment have been highlighted.

Seismic status in Bangladesh has been investigated using earthquake data recorded by the global network of USGS during 1980 to 2016. Seismicity parameters such as magnitude completeness Mc, b-value and a-value are being estimated. It has observed that the overall b-value in and around Bangladesh is of 0.84 which is seemed to be seismically active zone. As, reliable b-value assessment can lead to better seismic hazard analysis, reliable magnitude of completeness Mc can lead to b-value assessment of an area, this work has dealt and estimated magnitude of completeness Mc using various techniques for the whole region for a reliable estimation. Estimated Mc is obtained to be around 3.9-4.7, which lead to b-value of 0.93. Spatial variations of Mc  and b-value have been investigated for 1ox1o horizontal and vertical rectangular regions for the study area between 18-29°N and 84-95°E. Estimated Mc and b-value along with b-value are then averaged for the common regions in the pair of horizontal and vertical regions. Results are then being presented in the form of maps. The findings resemble as, the Mc is low at the border line of N-W Bangladesh, and a line from Cox’s bazaar to Sylhet through Hill tracts. Remain parts belong to the Mc value of 4.1-4.2, thus the b-value obtained is varying from 0.68 to 1.2, where, the value is higher at region in Chittagong and Barisal division that extends toward north through part of Dhaka to Sylhet and lower at Rajshahi, Rangpur and part of Khulna division, while a-value is varying from 5.0 to 7.2 mostly from west to east.ReferencesAbercrombie R.E., and Brune J.N., 1994. Evidence for a constant b-value above magnitude 0 in the southern San Andreas, San Jacinto, and San Miguel fault zones and at the Long Valley caldera, California. Geophys. Res. Lett., 21(15), 1647-1650.Aki K., 1965. Maximum likelihood estimate of b in the formula log N=a-b M and its confidence limits. Bull. Earthquake Res Inst., Tokyo Univ., 43, 237-239.Aki S., 1987. On nonparametric tests for symmetry. Ann. Inst. Statist. Math., 39, 457-472.Al-Hussaini T.M., 2006. Seismicity and Seismic Hazard Assessment in Bangladesh: Reference to Code Provisions. Meeting on Seismic Hazard in Asia ICTP, Trieste, Dec. 4-8.Amorese D., 2007. Applying a change-point detection method on frequency-magnitude distributions. Bull. Seismol. Soc. Am., 97(5), 1742-1749. Doi:10.1785/0120060181.Banglapedia, 2012. The National Encyclopedia of Bangladesh. http://en.banglapedia.org/index.php?title=Tectonic_Framework, retrieved on 31 Aug 2017.Cao A.M., and Gao S.S., 2002. Temporal variations of seismic b-values beneath northeastern Japan island arc. Geophys. Res. Lett., 29(9), 481-483. Doi:10.1029/2001GL013775.Das R., Wason H.R., and Sharma M.L., 2012.  Temporal and spatial variations in the magnitude of completeness for homogenized moment magnitude catalogue for northeast India. J. Earth Syst. Sci., 121(1), 19-28.Felzer K.R., 2008. Simulated aftershock sequences for a M 7.8 earthquake on the southern San Andreas fault. Seismol. Res. Lett., 80, 21-25.GSB, 2018. Seismic Zone Map of Bangladesh. http://gsb.portal.gov.bd/sites/default/files/files/gsb.portal.gov.bd/common_document/a6e75ad2_5acd_4fe3_911d_c9d25a7e349e/BD_Sciesmic-zonemap(NBC).pdf, retrieved on  31 March 2018.Gutenberg B., and Richter C.F., 1944. Frequency of earthquakes in California, Bull. Seismol. Soc. Am., 34, 184-188.Gutenberg B., and Richter C.F., 1956. Earthquake magnitude, intensity, energy and acceleration (second paper). Bull. Seismol Soc. Am., 46(2), 105-145.Hafiez H.E.A., 2015. Estimating the magnitude of completeness for assessing the quality of earthquake catalogue of the ENSN. Egypt. Arab J. Geosci., 8(1), 9315-9323. Doi:10.1007/s12517-015-1929-x.Hunting Geology and Geophysics Ltd., (1981), Interpretation and Operations report on an aeromagnetic survey in Bangladesh, Borehamwood, Hertfordshire, England.Iwata T., 2008. Low detection capability of global earthquakes after the occurrence of large earthquakes: investigation of the Harvard cmt catalogue. Geophys. J. Int., 174(3), 849-856. Doi:10.1111/j.1365-246X.2008.03864.x.Kagan Y.Y., 2002. Seismic moment distribution revisited: I. statistical results. Geophys. J. Int., 148(3), 520-541. Doi: 10.1046/j.1365-246x.2002.01594.x.Khan P.K., Ghosh M., Chakraborty P.P., and Mukherjee D., 2011. Seismic b-Value and the Assessment of Ambient Stress in Northeast India. Pure Appl. Geophys., 168(10), 1693-1706. Doi:10.1007/s00024-010-0194-x.Kolathayar S., Sitharam T.G., and Vipin K.S., 2012. Spatial variation of seismicity parameters across India and adjoining areas. Nat Hazards, 60(3), 1365-1379. Doi:10.1007/s11069-011-9898-1.Lomnitz-Adler J., and Lomnitz C., 1979. A modified form of the Gutenberg-Richter magnitude-frequency relation. Bull. Seism. Soc. Am., 69(4), 1209-1214.Marsan D., 2003. Triggering of seismicity at short timescales following Californian earthquakes. J. Geophys. Res., 108, B5, 2266. Doi:10.1029/2002JB001946.Mignan A., 2011. Retrospective on the Accelerating Seismic Release (ASR) hypothesis: Controversy and new horizons. Tectonophysics, 505(1), 1-16. Doi:10.1016/j.tecto.2011.03.010.Mignan A., and Woessner J., 2012. Estimating the magnitude of completeness for earthquake catalogs, Community Online Resource for Statistical Seismicity Analysis. Swiss Seismological Service, ETH Zurich, 145p. Doi:10.5078/corssa-00180805. Available at http://www.corssa.org.Naylor M., Orfanogiannaki, K., and Harte D., 2010. Exploratory data analysis: magnitude, space, and time. Community Online Resource for Statistical Seismicity Analysis, 42p. Doi:10.5078/corssa-92330203. Available at http://www.corssa.org.Ogata Y., and Katsura K., 1993. Analysis of temporal and spatial heterogeneity of magnitude frequency distribution inferred from earthquake catalogues. Geophys. J. Int., 113(3), 727-738. Doi:10.1111/j.1365-246X.1993.tb04663.x.Ogata Y., and Katsura K., 2006. Immediate and updated forecasting of aftershock hazard. Geophys. Res. Lett., 33, 10, L10305. Doi:10.1029/2006GL025888.Rashid H., 1991. Geography of Bangladesh, University Press Ltd, Bangladesh; 2nd edition, 545p.Reimann K.U., 1993. Geology of Bangladesh. Gerbruder Bornt Ramerg, Berlin, Germany, 160p.Siddique S., 2015. Gutenberg-Richter recurrence law to seismicity analysis of Bangladesh. IABSE-JSCE Joint Conference on Advances in Bridge Engineering-III, August 21-22, Dhaka, Bangladesh.Shi Y., and Bolt B.A., 1982. The standard error of the magnitude-frequency b-value. Bull. Seismol. Soc. Am., 72(5), 1667-1687.USGS, 2012. Earthquake Hazards Program. https://earthquake.usgs.gov/earthquakes/search/, USA, retrieved on 20 April 2017.Utsu T., 1999. Representation and analysis of the earthquake size distribution: a historical review and some new approaches. Pure Appl. Geophys., 155(2), 509-535.Wiemer S., and Wyss M., 2000. Minimum magnitude of complete reporting in earthquake catalogs: examples from Alaska, the western United States, and Japan. Bull. Seismol. Soc. Am., 90, 859-869. Doi:10.1785/0119990114.Woessner J., and Wiemer S., 2005. Assessing the quality of earthquake catalogues: Estimating the magnitude of completeness and its uncertainty. Bull. Seismol. Soc. Am., 95(2), 684-698. Doi:10.1785/012040007.Wyss M., Hasegawa A., Wiemer S., and Umino N., 1999. Quantitative mapping of precursory seismic quiescence before the 1989, M7.1 off-Sanriku earthquake, Japan. Annali Di Geoflsica, 42(5), 851-869.Zuniga F.R., and Wyss M., 1995. Inadvertent changes in magnitude reported in earthquake catalogs: Their evaluation through b-value estimates. Bull. Seismol. Soc. Am., 85, 1858-1866..Zuniga F.R., and Wiemer S., 1999. Seismicity patterns: Are they always related to natural causes? Pure Appl. Geophys., 155(2), 713-726.

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The Jamalgonj basin is an E-W elongated graben/half-graben type intracratonic basin in the Stable Shelf/Bogra Slope of the Platform area of Bangladesh. The present basin area is more sagged and deepest part of the Permian basin and is thought to be the easternmost continuation of Gondwana basins in India. The basin contains Gondwana sequence (>555 m) with more than seven coal seams of variable thickness. The coals are high volatile bituminous type and contain high ash, low sulphur, moderate to high vitrinite, moderate inertinite, low exinite and high mineral matter. Lower seams are high in vitrinite than those of the upper. The coal seams contain several intraseam partings of shaley coal, coaly shale and carbonaceous shale/mudstone. The thick coal seams were deposited in moderately to poorly drained, densely vegetated and comparatively long persistent backswamps adjacent to the channel-floodplain environments of fluvial regime. This type of thick seams are thought to be formed due to the combined interaction of several factors such as, localised aggradation of fluvial channel, abandonment of part of the channel area, slow and steady subsidence, long and protected time of peat accumulation, favourable palaeoclimate, palaeoflora, etc. with variable magnitude.

This work has presented yearly dry and wet seasons in the analysis of 28 years daily recorded temperature, relative humidity and rainfall data from 1988 to 2015 in Rajshahi division, Bangladesh using Hilbert frequency analysis. Analysis has estimated the seasonal boundaries in time according to the instantaneous frequency in cycles/day and the estimations are verified with studying power spectrum of the time series. Two boundaries are obtained in each analysis over the average of yearly analysis of four years. Obtained seasonal boundaries on 16 March and 20 October are indicated as the differentiator of wet season comprises of pre-monsoon and rain in each year. Results have also shown that the length of the wet season is varying ±11days. Estimations have further justified with average rainfall distribution as shown in this work. It is even difficult to differentiate rainy season in rainfall data, however, the estimated wet season using Hilbert analysis well supported the rainy season over temperature and humidity. The presented analysis may assist further to learn more about the seasonal variability in climate dynamics.