Satkhira Municipality is located in the extreme South-Western coastal region of Bangladesh. This area exhibits complex hydro-geochemical characteristics along with the increasing tendency of soil and water salinity which created a need of groundwater quality assurance. The objectives of the study were to identify the composition of groundwater followed by attempts to investigate spatial distribution pattern of groundwater quality. This was done to identify places with the availability of best quality of drinking water. This was achieved by combining the geographical information system, statistical analysis and diagrammatic presentation. A total of 100 deep tube well (450 to 600 feet) water samples were collected during monsoon and dry season in 2018 and were analyzed for hydro-geochemical parameters. The groundwater was neutral to alkaline (pH 7.01 to 8.66) in nature. Total dissolved solids ranged from 132.7 to 1436.0 mg L -1 which gradually increased from North to South direction. Sodium was the most dominant cation with mean value of 48.28 (±27.48) mg L -1 in monsoon and 105.35 (±66.73) mg L -1 in dry season. On the contrary, Clion was the dominant anion with mean value of 546.99 (±34.07) in monsoon and 424.68 (±398.59) mg L -1 in dry season. The high loading (>0.6) in principal component analysis indicated that the major ions originated from mineralization of rocks and soils, which was supported by Gibbs diagram. Silicate weathering supposed to be the responsible factor for releasing Na + ion, while Ca 2+ and Mg 2+ ion in groundwater came from both silicate and carbonate weathering. Three distinct types of groundwater facies e.g. the mixed NaCaCl, NaCaHCO 3 and NaCl were active along the study area, indicating that the underground cation exchange process. Our study will be helpful for the decision makers for planning a better operation and maintenance of groundwater resources.

The potential to sequester carbon by tree species in tropical regions such as Bangladesh is promising in regard to carbon sequestration (CS) potentiality and reducing CO2 emissions. This study focuses on perennial tree species within 488 hectares of Bangladesh Agricultural University (BAU) to assess the CS and to produce a C stock map for BAU. To compute the green and dry weight, weight of C and CO2 sequestration in the tree, a simplified methodology from the National Computational Science Institute of the Shodor Education Foundation was applied. A total of 27,543 trees comprising 424 species were taken into consideration, dividing the whole study area into four segments. B. ceiba and L. acidissima received the maximum and minimum green, dry, and C weight values. The topmost five carbon stock accumulating trees are M. longifolium (264,768 kg yr−1), S. mahagoni (257,290), A. lebbeck (118,310), M. indica (78,906), and T. grandis (51,744) whilst A. lebbeck is the major C stock accumulating tree within BAU. The top five CS potential are found for B. ceiba (181 kg), A. columnaris (139 kg), S. siamea (116 kg), F. elastica (113 kg), and F. religiosa (83 kg). To reveal the prospects of tree species in Bangladesh for emission reduction, the CS potential could be incorporated with the C trading scheme of the CDM (clean development mechanism) of the Kyoto Protocol.