Análisis ecotoxicológico del fungicida fosfito de sodio sobre una comunidad planctónica

Abstract

Agriculture is a strategic activity for the society, capable of causing impacts on the environment. Most of the impacts are related to the overuse of synthetic products for pest control and/or chemical fertilization. Sodium phosphite used as a fungicide presents low toxicity under standard laboratory conditions and type test organisms. However, no ecotoxicological tests have been performed to assist in the environmental risk assessment of this substance within a holistic framework. The present study shows the effect of the long-term exposure (60 days) of the fungicide sodium phosphite on the planktonic community, through outdoor microcosm tests. To determine the convenient concentrations to be used in the microcosms, a preliminary monospecific test was carried out with Daphnia magna in the laboratory. Considering its results, the levels of exposure to the microcosms were 5 and 10 mg/L. The results have shown no effect on the zooplankton community structure (taxonomic composition or abundance) associated with treatments. In addition, the community of primary producers, phytoplankton and periphyton, also showed negative response (abundance) under the exposure conditions. Present results indicate that the use of sodium phosphite at these concentrations does not represent a risk for the zooplankton community, however the lack of information about the effects on the phytoplankton structure should make the precautionary principle prevail in the use of this substance.