Pollutant dispersion characteristics in Dhaka city, Bangladesh

Air pollution is a major environmental concern in major cities around the world. The major causes of air pollution include rapid industrialization/urbanization and increased non environment-friendly energy production. This paper analyses the atmospheric pollutant such as carbon monoxide (CO) and particulate matter (PM) dispersion characteristics of Dhaka city. The yearly and diurnal variations of pollutant concentration are described by taking into consideration of both meteorological and emission source parameters highlighting washout effect due to rainfall and inversion phenomena. Concentration of PM (both PM2.5 and PM10) and CO in the ambient air are measured for a period of one year with Airmetric Minivol air samplers and Gas Chromatographic (GC) technique, respectively. The trend over the year shows an increase in the monthly average hourly PM and CO concentrations in winter months (November to March) when both PM10 and PM2.5 annual average concentrations (about 130 and 95 ??g m^?3, respectively) exhibit levels exceeding World Health Organization (WHO) guidelines as well as exceed more than twice the national standards of annual PM10 (50 ??g m^?3) and PM2.5 (15 ??g m^?3) concentrations. Such high pollutant concentrations may have significant health implications for residents of Dhaka city. It is also found that the PM concentration increases with the increase of wind speed during dry winter season and is also influenced by transboundary air pollution. The data and subsequent recommendations can be useful in formulating air quality management strategies for the Dhaka city.     

Long-term patterns in the diets of Japanese temperate bassLateolabrax japonicus larvae and juveniles in Chikugo estuarine nursery ground in Ariake Bay, Japan

Larval and juvenile Japanese temperate bass (Lateolabrax japonicus) samples were collected from a wide range of spatial gradients (covering a distance of approximately 30 km) in Chikugo estuary, Ariake Bay, Japan over a period of 8 yr (1997–2004) in order to observe changes in diet. Gut contents were studied by separating, identifying, counting, and estimating the dry weight of prey organisms. Copepod samples were collected during each cruise to observe the numerical composition, abundance, and biomass in the estuary. Considerable spatial and temporal variations were observed in copepod distributions in ambient water and the diets of the fish. Two distinctly different copepod assemblages were identified in the estuary: One in the upper estuarine turbidity maximum (ETM), dominated by a single speciesSinocalanus sinensis and the other in the lower estuary consisting of a multispecies assemblage, dominated byOithona davisae, Acartia omorii, Paracalanus parvus, andCalanus sinicus. The gut content composition of the fish in the upper estuary was dominated byS. sinensis, while in the lower estuary, it consisted ofP. parvus, O. davisae, andA. omorii. Within the size group analyzed (13.0–27.0 mm SL), the smaller individuals were found to feed on a mixed diet composed of smaller prey. The diets gradually shifted to bigger prey composed predominantly ofS. sinensis for larger size groups. Greater proportions of empty guts were recorded in the smaller individuals and dropped with increasing fish size. Higher dry biomass of copepods in the environment, as well as higher dry weights of gut contents, were recorded in the upper estuary, indicating that the upper estuarine ETM areas are important nursery grounds for the early life stages of the Japanese temperate bass. The early life stages of the Japanese temperate bass are adapted to use the upstream nursery grounds and ascending to the nursery areas to useS. sinensis is one of the key survival strategies of the Japanese temperate bass in the Chikugo estuary.     

Assessing factors affecting drought,earthquake, and flood risk perception: empirical evidence from Bangladesh

Natural Hazards - Understanding household disaster risk perception is crucial to formulate and apply disaster risk reduction strategies. Using survey data from 300 households from three highly...     

Geological and soil engineering properties of shallow landslides occurring in the Kutupalong Rohingya Camp in Cox’s Bazar,Bangladesh

Landslides - The Forcibly Displaced Myanmar Nationals (FDMN), historically known as ‘Rohingya’ who fled the 2017 ethnic atrocities and genocide in the Northern Rakhine State of Myanmar,...     

Modelling undrained behaviour of sand with fines and fabric anisotropy

Acta Geotechnica - Fabric anisotropy and fines content (fc) in sands modify significantly their mechanical behaviour, particularly as related to static liquefaction under undrained conditions. The...     

Python based location analysis of wind mills in urban environment

GeoJournal - Identification of appropriate location for windmills in landlocked states, like the state of Iowa requires consideration of multiple factors and analysis of a large database, which is...     

Effect of Face Losses and Cover-to-Diameter Ratio on Tunneling Induced Settlements in Soft Clay,Using Transparent Soil Models

Geotechnical and Geological Engineering - Reliable prediction of surface and subsurface settlements induced by shallow tunnels is important to minimize the adverse effects which may take...     

Geochemistry of ochreous precipitates from coal mine drainage in India

The deposition of ochreous is common by a consequence of acid mine drainage (AMD). The ochreous precipitated from the AMD sites around Tertiary coalfield of Assam, India were collected and characterized by X-ray diffractometry (XRD), Fe to S molar ratio, ammonium oxalate acid (pH 3.0) extraction, fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The ochreous mainly consists of goethite, schwertmannite, ferrihydrite and jarosite. Mineralogy of ochreous was controlled by the pH whereas formation of ferrihydrite was favored at high organic carbon content. Role of bacteria for the formation of secondary minerals was observed. Mobility of metals was controlled by the ochreous, and they were also retained during the process of phase transformation of poorly ordered iron-oxyhydroxysulfates into the stable forms.