Sistemas agroflorestais implantados em áreas de preservação permanente e seus efeitos na qualidade da água de riachos localizados na Amazônia Mato-grossense

Abstract

This study aimed to assess the environmental effects of Agroforestry Systems (SAF) on the water quality of streams located in rural areas of the municipality of Carlinda, north of the state of Mato Grosso, territory of the Portal da Amazônia (55°30' to 57 °00' W, 9°00' to 11°00' S). Five environments/systems were selected, three SAF of different ages, a Native Riparian Forest System (SMCN) and a Pasture System (Spas) to proceed with the environemntal monitoring. Five samplings and in site measurements were carried out to analyze physical, chemical and microbiological parameters of water quality, in dry and rainy periods, between 2017 and 2019. The results were compared with the standards established by CONAMA Resolution No. 357/ 2005, with descriptive statistical analysis, followed by Analysis of Variance (ANOVA), with Tukey's test (5%) and Principal Component Analysis (PCA), with determination of the correlation matrix, eigenvectors and eigenvalues. The environmental physical assessment was carried out according to the application of the Riparian, Channel and Environmental Inventory (RCE) and temporal analysis of land use and occupation in the years 2010 and 2019. The RCE applications revealed that, among the studied area, the SAF 2010 presented the best environmental integrity, which was classified as “good”. The SPas and SAF 2014 had the environmental integrity classified as "poor", resulting from the condition of almost non-existent riparian vegetation, thus corroborating with the temporal analysis of land use and occupation, which indicated the importance of riparian forest for the protection of streams. The comparison of water quality results, showed disagreement in the five systems studied, and the dissolved oxygen (DO) was the parameter that showed disagreement results, except in SPas. The presence of Escherichia coli, which indicates contamination of fecal origin, was observed in all systems, indicating an alarming situation in the SMCN, that the use of water for irrigation of vegetables. Through the PCA, it was possible to identify aspects of water quality degradation, mainly through the contribution of Total Nitrogen (Total N) and Total Phosphorus (Total P) in SAF 2012, as a consequence of land use for agricultural and cattle activities, as well that the high concentrations of total N in the SMCN, are related with the access of the cattle to the streams. Thus, the tools used were able to identify the positive effects of the five systems studied, but, aspects of degradation in the quality of the water and in the physical environmental attributesis a consequence of the agricultural and livestock activities that characterize the five systems.