The role of riverine overflow basins in nutrient retention and metabolic activity

The aim of this work was to analyze the effects of riverine wetlands on the water quality and river metabolism. For this purpose, four streams were studied: two of them surround a peri-urban area and have well-preserved riverine wetlands associated with the main channel, and the other two run through an urban area with the consequent degradation of their riverine wetlands by urban development. In each stream, three sections 50 meters long were sampled. The first one, located upstream of the riverine wetland zone (called “Arriba”), the second in the middle section of the water course that runs through the riverine wetland zone (called “Medio”), and the last one downstream of the riverine wetland zone (called “Abajo”). The variables studied included, in four periods of the year and in each section: physical-chemical parameters (temperature, conductivity, pH, dissolved oxygen, turbidity, dissolved and suspended solids, concentrations of nitrogen forms, and total and dissolved phosphorous) and biological parameters, linked to the metabolic activity of the biofilm and bacterial densities. In addition, at two sampling times, nutrient retention experiments were carried out in the middle section of the stream courses, using the tracer addition technique to characterize the nutrient spiral. The results show that the best preserved riverine wetlands a) significantly decrease dissolved oxygen and increase the concentration of suspended solids in the channel; b) act as sinks for P and N, increasing fluvial metabolic processes, such as respiration or primary production; c) result in high rates of assimilation of nutrients by the biota; and d) act as retention zones for coliform bacteria in the main channel. These general patterns can be detected in all systems, although much variability is observed in the channels, and their intensity varies throughout the year and depending on the physical-chemical conditions of the flow.

Bibliographic Details

Main Authors:	Cochero, Joaquín, Di Giorgi, Hugo, Donadelli, Jorge, Suárez, Jimena, Simonetti, Ramiro, Finkler, Nicolás Reynaldo, Gasparini Fernandes Cunha, Daví
Format:	Digital revista
Language:	spa
Published:	Instituto de Limnología "Raúl A. Ringuelet", Facultad de Ciencias Naturales y Museo (UNLP) 2020
Online Access:	https://revistas.unlp.edu.ar/bacuatica/article/view/10061
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