The excess of phosphorus in the environment can cause several negative impacts, especially with regard to water quality. Hence adequate methodologies are needed for assessing this risk at the watershed scale, emphasizing that the non-point agricultural sources impose greater estimate difficulties. The objective of this work was to propose an adapted methodology to quantify the dissolved and total reactive phosphorus movement in agricultural areas, based on the influence of agricultural crops (arboreous and herbaceous size), native pasture and its management in the State of Rio Grande do Sul (Southern Brazil). The methodology used was the study of reactive phosphorus release in plots covered by different crops and its relation to the methodology of calculation of maximum daily loads, currently accepted by the state environmental agencies for the environmental licensing of potentially polluting activities. The results show that the calculation of load of phosphorus contaminant currently in use, may be underestimating the Brazilian conditions, especially in Rio Grande do Sul, and that the new methodology allows one to include temporal variation as an element in the process of analysis, turning the licensing analysis into a dynamic and punctual process.
Environmental licensing; TMDL; agricultural contamination
