Herbicides and the Aquatic Environment

Abstract

The quality of water resources is perhaps currently the most discussed topic when it comes to environmental preservation, since aquatic ecosystems have been suffering changes worldwide in most cases irreversible. Such changes are often associated with human activities such as deforestation, release of industrial and domestic effluents, and even the use of pesticides in agricultural fields, which is one of sources that most contributes to the fall of quality of water resources. Pesticides are important to the agricultural system. However, it is crucial that they be used with responsibility in order to preserve the quality of the final product and the natural resources that support the production, especially soil and water (Oliveira Junior & Regitano, 2009). Pesticides are products whose function is to eliminate organisms causing damage to agricultural crops thus ensuring high productivity. Their classification is made according to target species (insecticides, herbicides, fungicides, acaricides, nematicides, etc..) (Alves-Silva & Oliveira, 2003, Sanches et al., 2003), patter of use (defoliants, repellents, and others) (Alves-Silva & Oliveira, 2003; Laws, 1993; Sanches et al., 2003), mechamisns of action (acetylcholinesterase inhibitor, anticoagulants, etc) (Alves-Silva & Oliveira, 2003) or chemical structure (pyretroids, organophosphates, carbamates, etc) (Alves-Silva & Oliveira, 2003; Laws, 1993). Although these molecules, when applied, have target organisms as their final destination, according to Macedo (2002) 99% of applied pesticides go into the air, water and soil, ie, only 1% reaches its target. This finding is quite disturbing as the world population grows; it means that the use of pesticides will increase (thus increasing food productivity) and natural resources will remain under intense threat from these molecules.