ATMOSPHERIC-POLLUTION BY AUXIN-TYPE HERBICIDES IN TALA VALLEY, NATAL

The effectiveness of restrictions on the use of several auxin-type herbicides allegedly damaging vegetables in the Tala Valley, Natal was evaluated by monitoring atmospheric samples over the area for 7 months. No volatile herbicide esters were found in air samples. Out of 280 air samples, 11 contained 2,4-D (2,4-dichlorophenoxyacetic acid), one dicamba (3,6-dichloro-o-anisic acid), one MCPA (4-chloro-o-tolyloxyacetic acid), and one 2,4,5-T (2,4,5-trichlorophenoxyacetic acid). The 2,4-D concentration ranged from 10 - 477 ng/m3, depending on sample duration and volume. Of the 87 rain samples, 11 contained 2,4-D, two 2,4,5-T, and one dicamba. The levels were 1.4 - 430-mu-g/litre for 2,4-D. Out of 27 dew samples, three contained 0.1 - 0.8 ng 2,4-D/cm2. Herbicide residues were therefore still found in the Tala Valley despite the restrictions.