AIR MONITORING FOR POLLUTION BY AUXIN-TYPE HERBICIDES

No 2,4-D iso-octyl ester was detected during air monitoring actions in the Tala Valley, Natal during 1987/1988 in spite of general use of the herbicide by sugarcane farmers outside the legally restricted area. Various techniques, including high volume air sampling and refinement of analytical methodology, were investigated to detect the suspected, extremely low concentrations of the herbicide. Regular detection of the polar forms of the auxin-type herbicides, including 2,4-D, indicated that esters of these herbicides in vapour form, were probably adsorbed to suspended particulate materials in the air and/or may be chemically transformed to polar forms. It is of great importance that air monitoring for the auxin-type herbicides, should include methodology to detect both the volatile and polar forms.