000			06371nas|a2200409 i 4500
005			20260817163233.0
008			021226s2000 th uzm rtt 00| a1eng d
035			_a.b11871969
099		9	_aAIT Thesis no. AS-00-28
100	1		_aRahman, Md. Mizanur
245	1	0	_aArsenic accumulation in Ipomoea reptans and the effects of phosphorus on its availability in soils of Bangladesh
260			_aBangkok : _bAsian Institute of Technology, _c2000
300			_a79 leaves
490	1		_aThesis ; _vno. AS-00-28
500			_aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science,School of Environment, Resources and Development
502			_aThesis (M.Sc.) - Asian Institute of Technology, 2000
520			_aSeries of pot experiments were conducted in the premises of Regional Laboratory, Soil Resource Development Institute, Khulna, Bangladesh in order to determine the distribution level of arsenic in plant (lpomoea reptans) parts (edible parts and roots) with respect to stage of plant growth and development (30 days and 60 days) and to assess the effects of phosphorus on arsenic availability in soils. Assessment was also made to explore the potential of I reptans to clean up the toxic arsenic from polluted soil environment. There were 9 treatments with the combination of 3 levels of arsenic (0, 2 and 30 mg As kg-1 soil) and 3 levels of phosphorus (0, 40 and 80 mg kg- 1 soil). Arsenic was applied as As20 3 and phosphorus as triple super phosphate (TSP). The control treatment was without arsenic and phosphorus (As0P0). The experiment was carried out in a 3x3 factorial design with 3 replicates for each treatment combination. Arsenic application in soils significantly increased its concentration in plants. In edible parts 30 days after sowing there were 24.85% of As2 and 46.20 % of As30 higher arsenic concentrations recorded compared to control (As0) . In case of roots these results were 19.35 % and 79 .10 % of As2 and As30 respectively compared to control. But arsenic recover fraction was higher in As2 then in As30 for both of edible parts and roots. The mean accumulated arsenic concentration both in edible parts and in roots did not significantly increase with increased Prates from 0 to 40 mg kg- 1 soil however, the concentration was significantly higher when P rates increased further to 80 mg/kg soil. There were 4.93 % and 13.03 % increased arsenic concentrations observed in edible parts in P 4o and Pso respectively compared to control (P0). In roots 1.93 % and 8.19 % increased arsenic concentration were resulted in P40 and P80 respectively compared to control. No significant effect from arsenic and phosphorus interaction was observed. Arsenic concentrations were significantly increased by 16.34 % and 31.96 % in As2 and As30 respectively compared to control in edible parts 60 days after sowing. Similarly in case of roots these results were significant with 15.42 % and 165.92 % higher arsenic concentration in As2 and As30 respectively compared to control. The arsenic recover fraction was higher in As2 than in As30 for both of edible parts and roots. The effect of phosphorus in this case was also highly significant in arsenic accumulation in edible paiis and compared to control there were 4.22 % and 9.21 % higher arsenic observed in P40 and P80 respectively. In this case arsenic and phosphorus interactions were found significant. In case of roots the significant results were observed in P4o and Pso compared to control, but no significant results were observed from P 4o tO Pso- No significant effects from arsenic and phosphorus interactions were also observed. The mean difference of arsenic concentration between the age of 30 days and 60 days of edible parts was highly significant. Similarly the mean difference of arsenic concentration between the age of 30 days and 60 days of root samples was also highly significant. The mean difference of arsenic concentration between edible parts and roots at the age of 30 days was highly significant. This difference was also highly significant at the age of 60 days. The maximum permissible limit of arsenic in plants for human consumption is only 1.0 mg kg-1 dry weight. It was found from this study that the minimum and maximum arsenic concentration in I. reptans were 4.61 mg kg- 1 dry weight in edible parts of 30 days and 21.96 mg kg-1 dry weight in roots of 60 days respectively. So, the vegetable crops grown in arsenic contaminated soil (10.0 mg As kg-1 soil or above) are not allowable for consumption. Phosphate fertilizers have enhanced on arsenic availability in soil solution and thus higher accumulation in plants. Therefore, P fertilizer management techniques should be further studied to avoid too much of P and thus stimulating a release of indigenous arsenic from the soil. However, a considerable residue of phosphate fertili zer remains in soils, therefore, this fe1iilizer should be applied knowing the P status of the soil through soil test. Removing the whole plant including roots of I. reptans out of soil at harvesting slows down rate of arsenic build up in soil. This crop thus can be used to clean up the toxic arsenic from polluted soils. Around 60 percent arsenic can be recovered from soil environment. This can be an extension package for farmers to practice.
650		0	_aArsenic
650		0	_aSoils _xPhosphorus content _zBangladesh
650		0	_aSoils _xArsenic content _zBangladesh
700	1		_aShivakoti, Ganesh P., _eChairperson
700	0		_aPreeda Pakpian, _eExamination Committee
700	1		_aYang, Yi, _eExamination Committee
710	2		_aDenmark, _eScholarship Donor
810	2		_aAsian Institute of Technology. _tThesis ; _vno. AS-00-28
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B06959
907			_a.b11871969 _bmnait _cu
902			_a240403
998			_b0 _c021226 _dm _ea _fu _g0
945			_lmnait
945			_lmnarc
942			_c22
942			_c40
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