ENVIRONMENTAL FATE OF HERBICIDES IN HAWAII, PERU AND PANAMA

摘要

Data on the fate and behaviour of herbicides in tropical soils are often unavailable. Here, the environmental fate of herbicides was compared in controlled field plots with the results derived from 'real world' pesticide use in tropical situations. As the intended herbicide use was to control illicit narcotic crops, sampling and verification are major problems because of the geographical remoteness, security concerns and political accessibility. Another fundamental problem is that exclusive use of either chemical analysis or biological monitoring may lead to an incomplete understanding of the environmental fate and ecological consequences of pesticide use. For hexazinone, tebuthiuron and imazapyr, the soil persistence and mobility, and the residual phytotoxicity to seven crops, were determined under controlled field conditions in Hawaii. This information was compared with field results in Peru and Panama for hexazinone, tebuthiuron and glyphosate. Herbicide dissipation was much faster under tropical than temperate zone conditions; also, herbicide persistence in Hawaii closely matched that found in the coca fields of Peru and Panama. Chemical and biological approaches together gave greater reliability to risk interpretation than would either approach alone; both showed low environmental risk for the pesticides tested.