EVALUATION OF NUTRIENT AVAILABILITY USING ION EXCHANGE RESINS IN A SEASONAL PERIOD IN THE CUCHUJAQUI RIVER BASIN
Ecosystems differ widely in nutrient supply rates because of differences in rates of decomposition, mineral weathering, and other processes. In protected areas in the Cuchujaqui basin in Northern Mexico, the nutrient fluxes can vary depending on the history of land use, topography, climate, soil nutrient accumulation, species composition and forest type. In some cases, this accumulation of nutrients may present a risk of contamination in the Cuchujaqui river which affects protected areas, rivers, aquifers and finally the flora and wildlife. The Cuchujaqui basin is characterized by a semi-arid climate. This region receives up to 70% of the annual rainfall generated during the North American Monsoon (NAM) in the months of July, August, and September when more nutrient movement is expected. In this project, we built and installed ion exchange cartridges and resin bags which were installed in two streams with different degrees of conservation within the Cuchujaqui river basin to measure the flow of nutrients. The ion exchange cartridges were installed in the ground (with different depths) during the summer. This method is characterized by undestroyed soil structure; thus, more representative information is obtained about the nutrient fluxes in the environment. At the end of the season, the cartridges were removed, divided into four different layers and each layer was extracted by 0.5 M H2SO4. The resin bags were anchored in the rock by resistant cables on the surface of the streams. This method captures the flow of nutrients carried by the streams on the surface. Since the installation, the resin bags were changed every two weeks throughout the summer. Each resin bag was extracted by 0.5 M H2SO4. Additionally, soil samples were taken and soil types were determined through soil profiling. Soil samples were used to evaluate P, NO3, NH4 and organic matter. Texture, structure, pH, and salinity were determined. The results with the ion exchange cartridges indicate that there is no significant difference between sites with nitrate concentration. Although, the concentrations of phosphate and ammonium present a significant difference between sites. The results with the resin bags indicate that there is no significant difference between sites with nitrate and ammonium concentrations. However, the concentration of phosphate presents a significant difference between the sites. In several previous experiments, resin cartridges have proven their efficiency to evaluate significant differences between agricultural production systems. In the same way, the resin bags have been effective in research to measure the availability of nutrients in natural ecosystems and laboratories. Until now, these methodologies had not been applied in nature reserves or natural ecosystems where it can demonstrate specifically the flow of nutrients that move through rivers or streams in an environment with different degrees of conservation after extreme rainfall events. Ion exchange cartridges and resin bags were found to be a useful tool to determine nutrient flows in semi-arid river basins during the rainy season.