R. Sultana
Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh- 2202
M.W. Zaman
Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh- 2202
SM.N. Islam
Department of Biotechnology, Bangladesh Agricultural University; Mymensingh- 2202
Phytoremediation, Arsenic, Hyperaccumulating weeds, Phosphorus, Sulphur. Calcium
Net-house of the Department of Agricultural Chemistry, BAU, Mymensingh
Risk Management in Agriculture
The experiment was conducted in the net-house of the Department of Agricultural Chemistry, BAU, Mymensingh from March to August 2004. The initial soil was collected from Vabokhali union, Sadar Upazila, Mymensingh at 0-15 cm depth. The soil contained 2.56 mg/kg arsenic. The post harvest soils of these pots after a series of phytoremediation study were used for this study. The experiment was carried out in Completely Randomized Design with three replications.
Treatments In the initial phytoremediation study there were seven treatments of arsenic viz, 0, 10, 20, 30, 50, 70 and 100 mg kg-1 Arsenic (Soil basis) from Na-Arsenate (NaAs02). Initially, urea, TSP, MP and gypsum were added at the rates of 135, 100, 70 and 60 kg ha-1 respectively in each pot. In the present study, there was no fertilizer application and the residual soil arsenic contents were considered as treatments.
In the phytoremediation study eight weed species were used. The weeds included barnyard grass (Echinochloa crusgalli), yellow nut sedge (Cyperus rotundas), joina (Fimbristylis miliacea), chesra (Scirpus juncoids), topapana (Pistia stratiotes), water taro (Monochoria hastata), water cress (Enhydra fluctuants), malancha (Altemanthera philoxeroides). The weed seedlings were collected from Agronomy farm area of BAU, Mymensingh and other places of this district which are known as arsenic free areas.The weed seedlings were transplanted in the experimental pots on 4th March, 2004. Three seedlings were transplanted in each pot. - The plants were harvested at 45 days of transplanting. The weeds were harvested carefully so that all the roots were collected. The weeds were washed repeatedly with water to remove all the soil particles. Then, the samples were air-dried followed by oven drying at 60°C for 24 hours. The weeds were weighed separately for root and shoot. Plant extracts were prepared separately for root and shoot samples: Digestion was completed using 0.5g plant and lg soil sample with HNO3followed by H202 at 120 °C temperature.
Chemical analysis: Total arsenic content of soil was determined from the digest by flow injection hydride generator atomic absorption .spectrophotometer (Unicam 969 with a hydride generator assembly) using matrix-matched standards (Welsch et aL, 1990). Analysis of phosphorus was done by stannous chloride method with the help of a spectrophotometer at 660 nm wavelength as mentioned by Jackson -(1973). The concentration of S in the root and shoot extract was determined turbidimetrically using BaSO4 with the help of a spectrophotometer at 420 nm wavelength as described by Page et aL (1982). Calcium was determined by atomic absorption spectrophotometric method (Issac and Kerber, 1971).
J. Bangladesh Agril. Univ. 4(2): 211-217, 2006 ISSN 1810-3030
Journal