Contamination and ecological risk assessment of trace elements in sediments of the rivers of Sundarban mangrove forest, Bangladesh.

In this study, total concentrations of 16 trace elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, Pb, Th and U) in sediments of the rivers of the Sundarban mangrove forest, after the catastrophic oil spill accident in the Sela river of Sundarban, were determined. The overall mean concentrations of V, Cr, Fe and Cd in surface sediments of the Sundarban are remarkably higher than available literature data of those elements. Trace element contamination assessment, using different environmental contamination indices, reveals that As, Sb, Th and U are low to moderately contaminated while Cd is moderately to severely contaminated in the sediments of this area. The multivariate statistical analyses were applied to reveal the origin and behavior of the elements during their transport in the mangrove ecosystem. High Cr, Ni, Cu and As concentrations suggest the risk of potentially adverse biological effects in the ecosystem.

Influence of plant population and nitrogen-fertilizer at various levels on growth and growth efficiency of maize.

Field experiments were conducted to evaluate plant population and N-fertilizer effects on yield and yield components of maize (Zea mays L.). Three levels of plant populations (53000, 66000, and 800,000 plants ha⁻¹ corresponding to spacings of 75 × 25, 60 × 25, and 50 × 25 cm) and 4 doses of N (100, 140, 180, and 220 kg ha⁻¹) were the treatment variables. Results revealed that plant growth, light interception (LI), yield attributes, and grain yield varied significantly due to the variations in population density and N-rates. Crop growth rate (CGR) was the highest with the population of 80,000 ha⁻¹ receiving 220 kg N ha⁻¹, while relative growth rate (RGR) showed an opposite trend of CGR. Light absorption was maximum when most of densely populated plant received the highest amount of N (220 kg N ha⁻¹). Response of soil-plant-analysis development (SPAD) value as well as N-content to N-rates was found significant. Plant height was the maximum at the lowest plant density with the highest amount of N. Plants that received 180 kg N ha⁻¹ with 80,000 plants ha⁻¹ had larger foliage, greater SPAD value, and higher amount of grains cob⁻¹ that contributed to the maximum yield (5.03 t ha⁻¹) and the maximum harvest index (HI) compared to the plants in other treatments.

Maternal serum zinc level and its relation with neonatal birth weight.

The present study was conducted in the Department of Obstetrics & Gynaecology, Mymensingh Medical College Hospital, Mymensingh and Molecular Microbiology & Central Laboratory of Bangladesh Institute of Nuclear Agriculture (BINA) from 15th November 2007 to 31st May 2009 to find out the relation between maternal serum zinc level with neonatal birth weight. Hundred pregnant women who were advised to take 61.8 mg zinc daily throughout pregnancy were assigned to study group while the pregnant woman did not take zinc orally were allocated into control group. Serum zinc levels were measured between 37-42 weeks gestation and birth weight were measured just after delivery. Data were processed and analyzed using SPSS version 11.5. The test used to analyze the data was descriptive statistics, Chi-square probability test, Pearson correlation, unpaired t-test and odds ratio. A probability value of <0.05 was considered significant. Majority (97%) of the cases who received zinc during their antenatal period had normal serum zinc (≥ 700µg/L) level compared to only 22% of the control group woman who did not receive zinc. Normal birth weight of babies in pregnant woman who received zinc is 5.7 times higher than the pregnant woman who did not receive zinc. As the present study was a cross-sectional one, further study with large sample size and prospective design is recommended.