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In recent years, cadmium (Cd) contamination in agricultural soils and its subsequent transfer to crops is one of the high-priority environmental and public health issues of global concern, especially in densely populated developing countries like Bangladesh. However, no effective strategy has been introduced or implemented yet to manage Cd-contaminated soils in order to sustain agricultural production with no human health risks. In this study, agricultural soil samples were collected from 60 locations of 10 upazilas from Tangail district to assess the extent of soil Cd contamination. The Cd concentration ranged from 0.83 to 4.08 mg kg−1 with a mean of 2.17 mg kg−1 in topsoil (0–15 cm), and from 0.67 to 3.74 mg kg−1 with a mean of 2.10 mg kg−1 in subsoil (16–30 cm). The values of contamination factor (CF) indicated that all the sampling locations were found to be highly contaminated with Cd. Pot trials with the application of different doses of biochar and vermicompost in Cd-contaminated soil (0.8 mg kg−1 Cd) revealed that integrated application of biochar (5 t ha−1) and vermicompost (5 t ha−1) was the best treatment that significantly (p

Cadmium (Cd) is a heavy metal which is not essential for human body. Cadmium enters into human body mainly through food consumption. Besides industrial wastes, phosphate fertilizers contain Cd which accumulates gradually in agricultural lands. To produce high quantity of food for about 160 million people of Bangladesh, agricultural lands need to be applied huge amount of fertilizes including TSP which add Cd to soils. It has been reported that in rice grains the cadmium concentrations were the highest in Bangladesh and Srilanka where the per capita rice intake is high, from a survey on four continents of 12 countries. The intake of these Cd containing foods may ultimately increase the Cd concentration in human kidneys and livers which might be related to the enhanced kidney patients in Bangladesh. There is lot of toxic effects of excess Cd on humans. The present review illustrates the urgency of further studies of Cd in Bangladesh. J. Environ. Sci. & Natural Resources, 11(1-2): 227-234 2018

An investigation was conducted to assess the impact of solid waste disposal on surrounding environment of Matuail landfill site of Dhaka city. Three different locations such as current dumping, abandoned and its surrounded agricultural areas of Matuail landfill were selected for soil and plant samples, leachate from active dumping and fish samples from treated leachate pond. The Cu, Zn and Pb concentrations were high in the dumping (360 µg g-1 Cu, 806 µg g-1 Zn and 382 µg g-1 Pb) and abandoned (199 µg g-1 Cu, 452 µg g-1 Zn and 519 µg g-1 Pb) areas that exceeded the permissible limits. The heavy metal concentrations in plant samples did not show any significant contamination except Cu, Zn and Pb that also exceeded the permissible limits. On the other side, the organic matter and nutrient concentrations such as N, P, K and S of both soil and plant samples are within desirable value in the studied area. The concentrations of DO, BOD, COD and TDS of the untreated leachate were found 1.34 mg L-1, 96 mg L-1, 1343 mg L-1 and 7120 mg L-1, respectively that exceeded inland surface water standard but after treatment the concentrations of DO, BOD and TDS in the treated leachate pond were found within the permissible limit. The presence of heavy metal in leachate is not contaminated as it is below the toxic limit. The bioaccumulation of fish from treated pond is extremely high of Fe, Mn, Pb and Ni that exceeded the WHOs permissible limit.

A study was conducted to determine the organic carbon fractions in the vertical sections of a benchmark wetland soil of Bangladesh (Arial Beel) and their dynamics that directly affect the biogeochemistry of soil, water and plant biomass ecosystem. Two distinctive soil series viz. Sara and Arial are characterized such as pH, moisture content, textural class, CEC, organic carbon (SOC), bulk density and total organic matter etc. Different extraction methods were used for the fractionation of dissolved organic carbon such as water-soluble Fraction (WSC), hot water extractable fraction (HWC; 80°C), labile fraction (CaCl2- extractable; LF), moderately labile fraction (Pyrophosphate-extractable; MLF), polyaromatic fraction (toluene + methanol extractable), Microbial Biomass C Fraction (MBF) and the remaining Resistant Fraction (RF). The total organic carbon content ranges from 0.72 to 1.95%; surface horizons had higher C than underneath horizons and prolonged inundation increased the C content mostly. Higher CEC of the soils had a positive correlation to HWC, MBC and RF. The DOC content particularly MLF was found higher in surface and substratum than subsurface horizons in most of the soils. The HWC and ML fraction had highly significant (p 1%) which is relatively resistant to further degradation and might be considered as sequestered C. Short inundated period and scope of winter Robi crops might have caused Sara soil to have relatively lower organic C and RF than Arial. Moreover, the amount of DOC fractions in Sara series was lower and that decreased with depth but in Arial series, fractions varied within the profile.

Six slow pyrolysis biochars viz. farmyard manure (FM), water hyacinth (WH), domestic organic waste (DW), quick compost (QC), corn cob (CC) and rice straw (RS) were analyzed for their physical and chemical properties. Biochar yielding capacity varied from 34 to 51%, depending on the used feedstock. Water hyacinth biochar exhibited the highest water holding capacity (495%), whereas corn cob biochar had the lowest (146%) regardless of its highest pore volume. Brunauer-Emmett-Teller (BET) specific surface area was found maximum among the plant derived biochars except corn cob. Rice straw biochar exhibited the least mean pore diameter while highest in domestic organic waste. All biochars possessed pH values more than 9. CEC of water hyacinth (WH) was highest, while lowest was in quick compost (QC) biochar. Smallest average particle size (0.54 ?m2) was exhibited by water hyacinth biochar. Organic carbon content ranged from 33 to 49%. Nutrient (N, P, K and S) status of biochar produced from domestic organic waste (DW) was found the maximum compared to the rest and corn cob (CC) biochar showed the lowest nutritional value.Bangladesh J. Sci. Res. 29(2): 111-122, December-2016

An investigation was carried out to assess the characteristics of leachate and its impact on surrounding agricultural land of the Matuail landfill site, Dhaka, Bangladesh. Leachate samples were collected from active dumping areas; soil and plant samples from three different sites of surrounding agricultural areas. Water quality parameters like pH, DO, BOD, COD, TDS were measured for leachate samples and heavy metals like Cu, Zn, Pb, Cd, Ni were analyzed for leachate, soil and plant samples. The results showed that untreated leachate concentrations of DO, BOD, COD and TDS were 1.34, 96, 1343 and 7120 mg/l, respectively that exceeded inland surface water standard but the concentrations of DO (7.49 mg/l), BOD (10 mg/l) and TDS (790/l) in the treated leachate pond were found within the permissible limits. The leachate samples are not contaminated with heavy metals as these are present below the toxic limits. The heavy metal concentrations in agricultural soils are below the permissible limits except Pb; but in plants the concentrations of Cu, Zn and Pb exceeded the critical limits.Bangladesh J. Sci. Res. 29(1): 31-39, June-2016

Experiment was carried out to assess the concentration of Zn, Cu, Pb, Fe and Mn in agricultural soil and plant near selected brick kilns. Soils and plants samples were collected from four points such as 250, 500, 1000 and 1500 m away from brick kilns. Three metals were found at elevated levels in the soils near brick kilns such as, Pb (92.5 to 214 mg/kg), Zn (86 to 156 mg/kg) and Cu (24.7 to 46.9 mg/kg). It may be caused due to burning of poor quality coal and fire woods. The uptake of heavy metals in the nearest areas (250 m) of the brick kilns was significantly higher than the areas far from the brick production and their concentrations range from 7 to 543 mg/kg for Pb, 23 to 101 mg/kg for Zn, 10 to 41 mg/kg for Cu, 35 to 1309 mg/kg for Fe and 26 to 126 mg/kg for Mn. Results indicated that soils and plants accumulated maximum amount of micronutrients within 500 to 1000 m distance from brick kilns significantly decreased with distance. Iron and manganese were not polluting the soils near brick kilns but affecting the plants. Therefore, it can be suggested that no agricultural crops should be grown within 1000 m distance from a brick kiln.Dhaka Univ. J. Biol. Sci. 25(1): 75-81, 2016

Three different soil series such as Gerua, Kalma and Khilgaon were identified in three different land types (high, medium high and medium low land). Soil and plant samples were collected from each land type following a catena. Soil samples were collected from surface, subsurface and substratum in each soil series and plant samples were collected from each soil series to examine how the soil characteristics affect nutrient uptake by plants. The uptake of N, P, S and Zn increased from Gerua to Kalma soil and decreased to Khilgaon. K uptake increased from Gerua to Khilgaon soils. The concentration of Fe, Mn and Cu decreased at first and then increased that were opposite to the status of N, P, S and Zn. The uptake of P and Mn were positively correlated (r2 = 0.845**, r2 = 0.767*) and the uptake of K and Fe were negatively correlated (r2 = –0.951**, r2 = –0.676*) with the soil nutrients. This indicates the variation in nutrient concentration influenced by different factors in the catena. The uptake of nutrients by plants varied significantly within the catena. Macro and micronutrients were accumulated by the plants and the soils studied in the experiment did not show any nutrient deficiency or any metal contamination.Bangladesh J. Sci. Res. 28(2): 113-121, Dec-2015

A pot experiment was conducted to investigate the effect of irrigation water collected from different industrial areas on Red amaranth (Amaranthus tricolor L.) and tomato (Solanum lycopersicum L.). Collected water samples were analyzed for various parameters, which include pH, DO, BOD, COD, P, NH3-N, K, S, Zn, Cu, Pb and Cd. The results were compared with the irrigation water quality standards by the Department of Environment (DoE) of Bangladesh and many of them were found several-folds higher than the permissible limit. The deterioration trends of the water samples are as follows: Tejgaon canal > Rampura canal > Sitalakhya river. Dry matter of vegetables grown on Tejgaon soil was significantly (p ? 0.05) higher than that of agricultural soil. Both red amaranth and tomato grown in Tejgaon soil accumulate highest concentration of heavy metals followed by Rampura and Sitalakhya soil. The concentrations of zinc (Zn), lead (Pb) and cadmium (Cd) in edible portions of both vegetables were found several times higher than the WHO prescribed permissible limits. The concentration of heavy metals in vegetables were found in the order Zn > Cu > Pb > Cd.Bangladesh J. Sci. Res. 28(2): 151-159, Dec-2015

Brick kiln is well known as one of the main sources of air pollution; however, the pollutants produced from it do not remain in the air, they ultimately fall down to the soil and pollute the surroundings, therefore, this study was carried out to assess the status of macro (N, P, K and S) and micro nutrients (Fe, Mn and Zn, Cu) in the agricultural environment near the brick kilns of Young Brahmaputra and Jamuna Floodplain soils. Composite soil and plant samples were collected from four distances such as 250 m, 500 m, 1000 m, and 1500 m in three different sites. Sulphur (2352–3378 mg kg−1), Zn (86–156 mg kg−1) and Cu (24.7–46.9 mg kg−1) are found in the elevated levels near brick kiln soils that is released due to burning of poor quality coal and fire woods. The alarming news is that plant uptake of S and micro nutrients in the nearest areas of the brick kilns are significantly higher than the areas far from the brick production and their concentration ranges from 23 mg kg−1 to 101 mg kg−1 for Zn, 10–41 mg kg−1 for Cu, 35–1309 mg kg−1 for Fe, 26–126 mg kg−1 for Mn and 2590–mg kg−1 for S. Data indicates both soil and plant received maximum amount of micronutrients and S concentrations within 500–1000 m distances from brick kilns. Iron and Mn concentrations vary within a permissible limit but the plant uptake is high. Nitrogen concentrations is increasing with the distance from the brick kilns in both soils and plants but no definite pattern of P and K accumulation was found. Research suggested avoiding agricultural practice nearby brick kiln soils due to micronutrient contamination in order to preserve adjoined agricultural environment.