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Under the present study, the adsorption capability of the activated carbon originated from Bombax ceiba fruit shell was examined using batch experimental mode. Bombax ceiba fruit shell was carbonized and chemically activated using zinc chloride (ZnCl2) as activating agent. The surface structure of the prepared activated carbon was examined by using scanning electron microscope (SEM). Some important experimental parameters namely pH of the solution, contact time and initial metal ion concentration in the solution, which affect the adsorption process were optimized. Maximum cadmium(II) removal from the aqueous solution was found at pH 9 with 0.3g/30mL adsorbent dose. The equilibrium in adsorption was attained after about 90 min of contact. Different adsorption isotherm models namely Langmuir, Freundlich and Temkin adsorption isotherm models were fitted to explain the equilibrium data obtained for the adsorption system. Temkin isotherm was found to show stronger correlation for cadmium(II) adsorption from the experimental solution onto the prepared adsorbent surface.

Background: Contamination of soil with heavy metals is an alarming issue around the world. Therefore, this study aimed to assess the contamination status of heavy metals in the soil of Mongla industrial area, Bangladesh. Methods: Soil samples were randomly collected from 20 sites and digested by wet digestion method. The concentrations of heavy metals (Mn, Fe, Cu, Zn, Cd, and Pb) were determined using atomic absorption spectrophotometer (AAS). The quality of soil was assessed based on the contamination factor (CF), geoaccumulation index (Igeo), enrichment factor (EF), and ecological risk index factor (ERIF) analyses. Results: The average concentrations of Mn, Fe, Cu, Zn, Cd, and Pb were obtained to be 258.08 ± 51.61, 3736.90 ± 322.17, 19.55 ± 6.49, 66.76 ± 18.32, 0.59 ± 0.13, and 10.40 ± 1.49 mg kg-1, respectively, which were below the permissible limit. The highest value of CF (0.74 ± 0.16), Igeo (0.35 ± 0.34), EF (24.86 ± 6.27), and PERIF (22.11 ± 4.81) was observed for Cd. The pollution of CF, Igeo, EF, and ERIF was classified as very severely polluted, unpolluted to moderately polluted, strongly to extremely polluted, and slightly polluted, respectively, with these heavy metals due to anthropogenic activities. One-way ANOVA indicated a significant difference between Zn and Cd concentrations (P < 0.05), whereas Pearson correlation showed a positive correlation between Zn-Pb (P = 0.01) and Fe-Zn (P = 0.05). Conclusion: There are different classes of contamination with heavy metals in the study area. Therefore, necessary steps should be taken and people’s awareness of the soil pollution should be raised. Keywords: Soil pollution, Heavy metals, Contamination factor, Geoaccumulation index, Enrichment factor, Ecological risk index factor

At Shailmari River basin, located in the central Ganges Delta and the southwestern coastal Bangladesh, groundwater is the only potable source for water supply due to incompatible surface water sources. However, salinity degradation along with arsenic and iron contamination poses a serious health threat to the basin community. Considering this, an investigation was carried out along both banks of the river to assess groundwater vulnerability and its quality for drinking by conducting multi-seasonal water sampling campaigns from 20 domestic wells and analyses (both in-situ and laboratory) for several physico-chemical (pH, EC, TDS and major ions) and biological (coliforms) parameters. The results show slightly alkaline groundwater in the study area with largely variable chemical composition, i.e. EC varies from around 1900 to 2700 μS/cm. The abundance of major ions indicates as Na+ > Ca2+ > Mg2+ > K+ for cations and > Cl- > > > for anions. As per the Canadian water quality index (CCMEWQI), almost all groundwater samples concentrate in the marginal category meaning that groundwater is frequently threatened. Besides, it is not fully safe for drinking as revealed from comparison of geochemical data with national and WHO water quality standards.

Narail Sadar Upazilla is a major agricultural productive region of Narail District, Bangladesh. The crop production here significantly depends on the Chitra River water for irrigation. The present study was undertaken with an aim to evaluate the usability of this river water for irrigation purpose during pre-monsoon, monsoon and post-monsoon. Sampling was conducted three times in each season both in high tide and low tide. The collected samples were analyzed for some physicochemical parameters including pH, electrical conductivity (EC), total dissolved solid (TDS), major cations (Na+, K+, Ca2+ and Mg2+) and major anions (HCO3−, PO43−, SO42−, Cl− and NO3−). The calculated chemical indices’ values for the collected water samples during pre-monsoon indicate that this river water is chemically suitable for irrigation during pre-monsoon with respect to sodium adsorption ratio (SAR), residual sodium carbonate (RSC) and permeability index (PI). The values of all chemical indices declare this river water fitness for use in irrigation both in monsoon and post-monsoon. According to Wilcox diagram, all of the water samples irrespective of tide and sampling stations fall within “permissible to doubtful” category during pre-monsoon while the water samples collected in both tide from all stations fall within “excellent to good” category during monsoon and post-monsoon. The United States Salinity Laboratory (USSL) diagram certifies this river water as C1-S1 (low salinity along with low sodium level) type during monsoon and post-monsoon which makes the river water suitable for use in irrigation in these two seasons while the water is mostly C3-S1, C3-S2 and C3-S3 (high salinity along with low to high sodium level) type in pre-monsoon which makes the river water restricted for use in irrigation in this season.

Background: Vegetables are the main source of nutrients for the human being but the intake of contaminated vegetables causes several diseases. Therefore, the aims of this study were to examine heavy metals concentration in leafy, fruit and root vegetables and their growing soil in Mongla, Bangladesh; and to estimate the health risks (non-carcinogenic and carcinogenic) caused by heavy metal exposure through ingestion of vegetable using hazard quotient (THQ) and target cancer risk (TCR). Methods: United States Environmental Protection Agency (USEPA) deterministic approaches were used to assess the potential health risks to the human. Results: The average concentration of Fe, Cd, and Pb was 489.47, 0.48 and 8.15 mg/kg respectively, which was above the permissible limit recommended by WHO/FAO. Furthermore, THQ values for these metals and combined impacts of all metals (HI) were greater than the acceptable limit (1.0) which indicated a potential non-carcinogenic health risk. TCR values of Cd and Pb were greater than USEPA risk limit ( greater-than 10 -6); which exerts moderate to high carcinogenic risk to the human. Conclusion: The total health risk index showed that the consumption of vegetables from this study area poses a health risk and therefore regular monitoring of heavy metals is strongly recommended.

Surface water has become one of the most vulnerable resources on the earth due to deterioration of its quality from diverse sources of pollution. Understanding of the spatiotemporal distribution of pollutants and identification of the sources in the river systems is a prerequisite for the protection and sustainable utilization of the water resources. Multivariate statistical techniques such as Principal Component Analysis (PCA) and Factor Analysis (FA) were applied in this study to investigate the temporal and spatial variations of water quality and appoint the major factors of pollution in the Shailmari River system. Water quality data for 14 physicochemical parameters from 11 monitoring sites over the year of 2014 in three sampling seasons were collected and analyzed for this study. Kruskal-Wallis test showed significant (p < 0.01) temporal and spatial variations in all of the water quality parameters of the river water. Principal component analysis (PCA) allowed extracting the contributing parameters affecting the seasonal water quality in the river system. Scatter plots of the PCs showed the tidal and spatial variation within river system and identified parameters controlling the behavior in each case. Factor analysis (FA) further reduced the data and extracted factors which are significantly responsible for water quality variation in the river. The results indicate that the parameters controlling the water quality in different seasons are related with salinity, anthropogenic pollution (sewage disposal, effluents) and agricultural runoff in pre-monsoon; precipitation induced surface runoff in monsoon; and erosion, oxidation or organic pollution (point and non-point sources) in post-monsoon. Therefore, the study reveals the applicability and usefulness of the multivariate statistical methods in assessing water quality of river by identifying the potential environmental factors controlling the water quality in different seasons which might help to better understand, monitor and manage the quality of the water resources.

Water quality is the critical environmental determinant that influences the agricultural production and therefore, the economy that solely depends on its agricultural productions. Batiaghata Upazilla is one of the major crop productive areas of Khulna region and the agricultural production here largely depends on the natural water of the Shailmari River system around it. The present study was conducted to assess the suitability of this coastal river water for irrigational use. 66 water samples were collected during this study in three consecutive agricultural seasons, viz., pre-monsoon (22), monsoon (22) and post-monsoon (22) from 11 sampling stations within the river system considering the high (11) and ebb (11) tides for each station. Standard methods were followed throughout the study period for the collection of the samples and analysis of major physicochemical parameters (pH, EC, TDS, salinity, Na, K, Ca, Mg, Cl, HCO3, SO4, NO3 and PO4). Hydrocehmical characterization using Piper trilinear diagram shows that the water of the river system is Na-Cl dominated saline water type in pre-monsoon, whilst most of the samples of the river and the connected channel are characterized as fresh water of Ca-Mg-Na-HCO3 and Ca-Na-Mg-HCO3 types in monsoon and post-monsoon respectively. The calculated values of chemical indices like SAR, %Na, KI, PI and MH using the results of the analysed parameters indicate that the river water is chemically unsuitable for use in irrigation during pre-monsoon, while in the monsoon and post-monsoon the river water is within good to permissible limit for the use in the agricultural fields. However, high %Na, KI and MH values with high salinity of the channel water limit its use in agricultural applications in monsoon and post-monsoon. The USSL (United States Salinity Laboratory) diagram depicts that the river water is C4-S4 type with very high salinity and sodium content in pre-monsoon, while in other seasons the water is mostly C1-S1, C2-S1 or C2-S2 types (low to moderate salinity and sodium) in the river. Wilcox diagram shows that the river water is “suitable” for irrigation during monsoon and post-monsoon as the most of the samples range within “Excellent to Good” and “Good to permissible” categories, while it is “unsuitable” for crop irrigation during pre-monsoon when SAR (Sodium Adsorption Ratio) and EC (Electrical Conductivity) values of the water reach to their peaks.

This analysis observed the seasonal variation in the temperature dependent physico-chemical parameters [pH, Transparency, Salinity, Electrical conductivity (EC), Total Dissolved Solid (TDS), Total Alkalinity, Total Acidity, Dissolved Oxygen (DO) and Free Dissolved CO2] of surface water in a coastal river in Bangladesh. Composite samples from four different sampling points that considered high and low tides were collected and analyzed in three main consecutive seasons: rainy, winter and summer. The study has revealed that most physico-chemical parameters are not a serious problem for Bhadra River eco-system and water quality shows significant seasonal changes. The statistical analysis unveiled a positive correlation of temperature with pH, Transparency, Salinity, EC, TDS, Total Alkalinity, Total Acidity and Free Dissolved CO2 but only negative correlation with DO.