Mineralization of 14C-ring Labelled 2,4-D in Egyptian Soils Under Aerobic and Anaerobic Conditions
- Author:
S.M.A.D.ZAYED
1
;
M.FARGHALY
;
H.TAHA
Author Information
1. National Research Center
- Keywords:
14C-ring labelled;
Organochlorine pesticide;
Egyptian soil;
Radiochemicals
- From:
Biomedical and Environmental Sciences
2002;15(4):306-314
- CountryChina
- Language:Chinese
-
Abstract:
Obiectives To study the mineralization of 2,4-D in clay and clay loam Egyptian soils under subtropical conditions over a period of 90 d. Methods Using 14C-ring labelled pesticide, laboratory studies under aerobic and anaerobic conditions were conducted. 14C-activity in solutions was directly determined by liquid scintillation counting. Unextractable soil residues were determined by combustion.The nature of methanolic 14C-residues was determined by thin layer and high performance liquid chromatographic analysis. Results Under aerobic conditions 10%-14% of applied dose was mineralized during 90 d irrespective of soil type. The soil extractable pesticide residues decreased with time and the bound residues gradually increased. The highest binding capacity of about 26%-29% was observed in clay soil under aerobic conditions after 90 d. A good balance sheet was obtained and the percentage recovery was generally between 91% and 100%. Conclusion The mineralization of 2,4-D in clay soil was higher than that in clay loam soil under anaerobic conditions.Under aerobic conditions, the soil type had no influence on mineralizaion capacity of 2,4-D during 90 d. The soil binding increased with time whereby the extractable 14C-residues simultaneously decreased.Chromatographic analysis of the methanol extractable 14C-residues of soils revealed the presence of 2,4-D as a main product together with 2,4-dichlorophenol.
