Atmospheric pollution by auxin-type herbicides in Tala Valley, Natal

Abstract

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/m 3, 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 μg/litre for 2,4- d. Out of 27 dew samples, three contained 0.1 – 0.8 ng 2,4- d/cm 2. Herbicide residues were therefore still found in the Tala Valley despite the restrictions.