Arsenic accumulation in Ipomoea reptans and the effects of phosphorus on its availability in soils of Bangladesh | |
| Author | Rahman, Md. Mizanur |
| Call Number | AIT Thesis no. AS-00-28 |
| Subject(s) | Arsenic Soils--Phosphorus content--Bangladesh Soils--Arsenic content--Bangladesh |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AS-00-28 |
| Abstract | Series 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. |
| Year | 2000 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AS-00-28 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems (AS) |
| Chairperson(s) | Shivakoti G. P.;Preeda Parkpian; |
| Examination Committee(s) | Yi, Yang; |
| Scholarship Donor(s) | Denmark |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2000 |