Balance of nitrogen and phosphorus in a reservoir in the tropical semiarid region

Eunice Maia De Andrade,Antônio Givanilson Rodrigues Da Silva,Fernando Bezerra Lopes,Isabel Cristina Da Silva Araújo,Kássia Crislayne Duarte Ferreira

doi:10.5935/1806-6690.20200020

Eunice Maia De Andrade, Antônio Givanilson Rodrigues Da Silva + Show 3 more

Open Access

https://doi.org/10.5935/1806-6690.20200020

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Journal: REVISTA CIÊNCIA AGRONÔMICA	Publication Date: Jan 1, 2020
Citations: 8	License type: cc-by

Abstract

In relation to the process of eutrophication of water reservoirs, it is necessary to understand the nitrogen and phosphorus supply, as well as they support the process of eutrophication. In seeking to quantify the balance of nitrogen and phosphorus, as well as to identify the effect of climatic seasonality on their dynamics, 21 campaigns were carried out for water collection. The campaigns took place from April 2008 to December 2012 at the Oros reservoir, located in the semi-arid region of Brazil in the south-central part of the State of Ceara. Based on dataset it was possible to calculate the inflow and outflow of total nitrogen (TN) and total phosphorus (TP). The reservoir becoming a storage place for the nutrients transported by the flow of water from the drainage network. A total of 176 tons of nitrogen and 230 tons of phosphorus were retained in the reservoir. The TN and TP retained in the reservoir can lead to the water being compromised by eutrophication, increasing the financial cost of water treatment and compromising water availability for consumption use. Because it is a predominantly agricultural basin, and the nutrients show a similar input trend in the reservoir, it is believed that the primary source of nutrients is agriculture and livestock. There has been an increase in nutrient input of over time. Reservoirs in semi-arid regions are unique as regards nutrient load during dry periods, since even without fluvial input, nutrient concentrations generally remain steady or increase.

Highlights

The accelerated growth in population, coupled with the uncertainty of the spatial and temporal distribution of rainfall in semi-arid environments (ANDRADE et al, 2016), results in the water deficit always present in these regions (KAMPF et al, 2016; VAROL, 2013)
A greater contribution to the nutrient load in waterbodies increases the net production of the ecosystem, shifting the system towards autotrophy (BECKER et al, 2010), with the proliferation of phytoplankton (ROCHA; ANDRADE; LOPES, 2015; YANG et al, 2012)
This activity is a direct source of nutrients with the highest values for chlorophyll-a, contributing directly to the increase in eutrophication

Summary

Introduction

The accelerated growth in population, coupled with the uncertainty of the spatial and temporal distribution of rainfall in semi-arid environments (ANDRADE et al, 2016), results in the water deficit always present in these regions (KAMPF et al, 2016; VAROL, 2013). In the Brazilian semiarid region, climate variability, the long water retention time and high rates of evapotranspiration, added to anthropic action upstream of the basin, contribute to an increase in nutrient concentrations, in the water column, and acceleration of the eutrophication process of the aquatic ecosystem (GONZÁLEZ; ROLDÁN, 2019). The main sources of N for continental aquatic ecosystems are the biological fixation of nitrogen by phytoplankton (BECKER et al, 2010); rainfall (GIESE et al, 2011); the input of domestic and industrial effluent (LI et al, 2015) and farming activities (ESTEVES, 2011)

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