Wetland nutrient retention and multitemporal growth – Case study of Riacho Fundo’s Wetland

Abstract

Aim: The aim of this research was to evaluate the nutrient retention of Riacho Fundo’s wetland in controlling Lake Paranoá (Brasilia, Brazil) eutrophication analyzing its ability to retain nitrogen and phosphorus. Furthermore, the article aimed at verifying the multitemporal growth rate of Riacho Fundo’s wetland. Methods Five sampling points were distributed along the wetland, from its beginning to its outflow into Lake Paranoá. Twenty-five field campaigns during periods of drought and rain from November 2011 to October 2012 with intervals of fifteen days were accomplished. The parameters total nitrogen and total phosphorus were analyzed and for comparison between the sampling points a non-parametric statistical analysis was performed and the efficiency of retention of these parameters between input and outputs of the wetland was calculated. For the analysis of multitemporal pace of growth in the area of wetland, water area and was estimated by processed satellite images of the years 1973, 1985, 1995, 2005 and 2011. Results The general behavior of the analyzed nutrients was decay between the entry point and exit point of showing an overall average retention of nitrogen 36.66% and 33.95% overall average total phosphorus. By image processing was possible to estimate that the surface of the lake was lost 0.5273 km2 or 84.07% of the initial area in the range of 38 years. Conclusion Despite having lost water area, Lake Paranoá gained a natural filter that retains nutrients that could be being invested in it and so can cause eutrophication of its waters. Thus, the wetland provides an ecological service of water treatment and preservation of aquatic and terrestrial Lake Paranoá life and the wetland should be considered as an importanttheme in Lake Paranoá management.

Influence of Land Use and Land Cover on the Quality of Surface Waters in the Miranda River Watershed, Brazilian Pantanal

“…It is also noted that Total Phosphorus values were higher in rainy seasons compared to the drier period (Figure 13). In the study conducted by Dias & Baptista [9] in the wetland area of Riacho Fundo, Brasília, Brazil, an average retention of 34% for TP between the inlet and outlet points analyzed by the authors was observed. After an extensive literature review on nutrient removal in wetlands, Fisher and Acreman [12] identified that 84% of the studied wetlands showed Phosphorus retention, 10% indicated an increase in Phosphorus, and in 6% of the studied areas, there was no difference between the input and output of wetlands.…”

“…This is due to water infiltration through saturated layers of anoxic organic sedimentary material and plant debris with high denitrification potential, so that high denitrification rates are common in wetlands and riparian zones rich in organic matter [41]. Dias & Baptista [9] also observed the reduction of TN in the wetland area of Riacho Fundo, Brasília, Brazil. The authors found an average retention of 36.7% for TN between the inlet and outlet of the wetland area.…”

“…Thus, conducting an analysis of the relation between water quality and different types of land use and cover is an important step in the management of natural resources, developing conversion strategies, and guiding the sustainable use of these resources. In this regard, studies have analyzed the influence of land use and cover on water quality through multiple approaches; utilizing correlation coefficients between quality and land use [8], comparative analysis between input and output [9], through the use of regression equations [10], and multivariate analysis [11]. Although many approaches are being evaluated to analyze the influence of land use on water quality, most studies rely on limited time series data, often from only a single year or a single monitoring point, or few parameters.…”