The fate of paraquat in an irrigated sweet corn plot in Thailand | |
| Author | Anuttara Hongtong |
| Call Number | AIT Thesis no.EV-05-37 |
| Subject(s) | Paraquat--Thailand Sweet corn--Thailand |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | The fate of paraquat in an inigated sweet corn plot, Thailand was investigated. The study aims to understand the degradation of paraquat in both field and laboratory conditions. Transportation of paraquat to the environment; soil, water, yield of sweet com were expected and analyzed by spectrophotometric method. Adsorption of paraquat in clay soil at Thamuang site higher than in loamy soil at Panomthuan site and tend to decrease by photodegradation after several days of application at both site. Half life (DTso) of paraquat at Thamuang site (28 days) longer than Panomthuan site (7 days) because higher strongly absorbed to clay soil than loamy soil. Vertical movement of paraquat in soil was limited through deeper soil by the adsorption and was limited in the top of surface soil (0-3 cm). The horizontal transportation of paraquat to surface water was also limited because almost paraquat absorbed to soil particles and suspended solids presented in irrigation water at initial day after application. Photodegradation of paraquat in biometer flask was restricted only 0.92% and 2.31 % for 26.25 and 52.5 mg/kg, respectively, in the incubation period of 45 days. Photodegradation was occurred since day 1 of application whereas biodegradation was occurred after day 38, by the degradation rate of paraquat in biometer flask much slower than in the field experiment. In distilled water without sediment or plants, 89% of normal recommended rate (1,725 mg/L) and 85% of double recommended rate (3,450 mg/L) of paraquat were degraded by sunlight in 75 days. No paraquat residue was detected in the grains of sweet com crop which harvested within 3 weeks after paraquat application as herbicide. Note should be made that paraquat decomposition in the tropical agricultural soil was significantly influenced by strong sunlight with adequate soil moisture as well as microorganisms around the root rhizosphere of crops. Because of high rate of paraquat reduction after application, potential risk derived from downward transport to groundwater is unlikely providing that the cultivated soils would have texture between clay and loamy soil. |
| Year | 2005 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Preeda Parkpian; |
| Examination Committee(s) | Shipin, Oleg V. ;Thavee Sangthong;.Dumrongsak Deowanish ; |
| Scholarship Donor(s) | Royal Thai Government ; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2005 |