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

Andrade, Eunice Maia de; Ferreira, Kássia Crislayne Duarte; Lopes, Fernando Bezerra; Araújo, Isabel Cristina da Silva; Silva, Antonio Givanilson Rodrigues da

doi:10.5935/1806-6690.20200020

Cited by 10 publications

(6 citation statements)

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“…The variable, chlorophyll a, had a high weight (>0.825), and is considered an indicator of the presence of nutrients, especially phosphorus and nitrogen, as seen in component 1. The presence of chlorophyll a in aquatic systems represents the effect of the eutrophication process, which is the phenomenon by which an ecosystem becomes increasingly productive through enrichment with nutrients (ANDRADE et al, 2020;CHAVES et al, 2019;LOPES et al, 2014a). Eutrophication has an environmental impact on a global scale, and is one of the most serious problems related to water conservation (SCHINDLER, 2012).…”

Section: Resultsmentioning

confidence: 99%

Dinâmica limnológica em reservatório artificial e rio intermitente na região semiárida em função do uso e ocupação do solo

Duarte

Pereira

Lima

et al. 2021

RCA

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Remote sensing coupled with the measurement of physical, chemical and biological variables is an important tool in water resource management. The aim of this study, therefore, was to evaluate the dynamics of the physical, chemical and biological variables of the waters of an intermittent river and an artificial surface reservoir using multivariate analysis and in response to land use and occupation in the hydrographic basin. The study was carried out in the hydrographic basin of the River Cruxati in four study areas (three river areas and one artificial reservoir), with images obtained from the OLI sensor of the Landsat-8 satellite. The limnological variables measured were pH, electrical conductivity, dissolved oxygen, turbidity, nutrients (total nitrogen and total phosphorus) and chlorophyll a. The limnological variables were analysed using Principal Component Analysis -PCA, Tukey's test and Cluster Analysis. Eutrophication of the areas under study was calculated using the Trophic State Index. The PCA allowed three components to be selected that indicated the quality of the surface water, river and artificial reservoir, explaining 88.57% of the total variance. The limnological variables responsible for the grouping were electrical conductivity, dissolved oxygen and turbidity. Land use and occupation has influenced water quality in the stretches of river. Anthropisation has had an influence on the levels of dissolved oxygen, and the presence of agricultural areas has caused an increase in turbidity. However, the most conserved landscape (artificial reservoir) had the highest degree of eutrophication due to the difference in water dynamics between the lentic and lotic environments.

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Section: Resultsmentioning

confidence: 99%

Dinâmica limnológica em reservatório artificial e rio intermitente na região semiárida em função do uso e ocupação do solo

Duarte

Pereira

Lima

et al. 2021

RCA

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“…Eutrophication, one of the world's most critical environmental issues concerning reservoirs and other aquatic environments, is often associated with consistent nutrient enrichment that causes uncontrolled phytoplankton growth and subsequent harmful algae blooms (Schindler, 2006;McCrackin et al, 2017;Padedda et al, 2017). Regarding the nutrients that in uence the eutrophication of aquatic ecosystems, total nitrogen (TN) and total phosphorus (TP) have the most signi cant contribution, as they are essential for the growth of phytoplankton (microalgae and cyanobacteria) and macrophytes (aquatic plants) (Paerl et al al., 2016;Andrade et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…More recently, researchers have used empirically based models to explore the correlation of Chl-a with other parameters such as reservoir characteristics, watershed occupation, and physicochemical characteristics of the water (Tang et al, 2019;Franklin et al, 2020;Hara et al, 2020;Yuan and Jones, 2020;Mamun et al, 2021a) and hydroclimatic variations (volume, precipitation, temperature, air velocity) (Wang et al, 2014;Paerl et al, 2016;Tang et al, 2019). Despite being simple to implement, these models are developed for lakes and reservoirs with regional characteristics, which can lead to signi cant prediction errors in regions with water de cits and a high degree of uncertainty in the spatio-temporal distribution of rainfall, such as tropical reservoirs (Chaves et al, 2019;Andrade et al, 2020;Lopes et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Chlorophyll-a prediction in tropical reservoirs as a function of hydroclimatic variability and water quality

Guimarães

Neto

2023

Preprint

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The study goal was to determine spatio-temporal variations in chlorophyll-a (Chl-a) concentration using models that combine hydroclimatic and nutrient variables in 150 tropical reservoirs in Brazil. The investigation of seasonal variability indicated that Chl-a varied in response to changes in total nitrogen (TN), total phosphorus (TP), volume (V), and daily precipitation (P). Simple linear regression models showed that nutrients yielded better predictability of Chl-a than hydroclimatic variables. Fitted relationships between Chl-a and the above-mentioned parameters resulted in equations capable of representing algal temporal dynamics and blooms, with an average coefficient of determination of R² = 0.70. Chl-a blooms presented seasonal and interannual variability, being more frequent in periods of high precipitation and low volume. The equations demonstrate different Chl-a responses to the parameters. In general, Chl-a was positively related to TN and/or TP. However, in some cases (22%), high nutrient concentrations reduced Chl-a, which was attributed to limited phytoplankton growth driven by light deficiency due to increased turbidity. In 49% of the models, precipitation intensified Chl-a levels, which was related to increases in the nutrient concentration from external sources in rural watersheds. Contrastingly, 51% of the reservoirs faced a decrease in Chl-a with precipitation, which can be explained by the opposite effect of dilution of nutrient concentration at the reservoir inlet in urban watersheds. In terms of volume, in 67% of the reservoirs, water level reduction promoted an increase in Chl-a as a response of higher nutrient concentration. In the other cases, Chl-a decreased with lower water levels due to wind-induced destratification of the water column, which potentially decreased the internal nutrient release from bottom sediment. Finally, an application of the model to the two largest studied reservoirs showed greater sensitivity of Chl-a to changes in water use classes regarding variations in TN, followed by TP, V, and P.

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“…Water has become increasingly more degraded over recent decades, precluding the use of important reservoirs (ANDRADE et al, 2020;CHAVES et al, 2019;LOPES et al, 2014a;ROCHA et al, 2016;SANTOS et al, 2014). Eutrophication is a major problem for water management around the world, and refers to the process by which aquatic environments are enriched with nutrients, mainly phosphorus and nitrogen, which are essential for the growth of phytoplankton (microalgae and cyanobacteria) and macrophytes (aquatic plants).…”

Section: Introductionmentioning

confidence: 99%

Modelling chlorophyll-a concentrations in a continental aquatic ecosystem of the Brazilian semi-arid region based on remote sensing

Lopes

Barbosa

Novo

et al. 2021

Revista Ciência Agronômica

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Remote-sensing data are essential to evaluate dynamic processes such as eutrophication and increases in the concentration of suspended sediments in continental aquatic systems. The aim of this study, therefore, was to develop models to estimate chlorophylla concentrations from remote-sensing data in continental waters of the Brazilian semi-arid region. The study area corresponds to the Orós reservoir, located in the state of Ceará. The models were developed based on measurements taken at 20 sampling points. Water samples were collected from the reservoir to i) analyse the chlorophyll-a, electrical conductivity, pH and turbidity; ii) take optical measurements in situ of water transparency and spectral radiance. Radiance measurements were carried out using an ASD FieldSpec ® 3 Hi-Res spectroradiometer. The spectral data were later transformed into reflectance values and used to test the performance of several models found in the literature for estimating chlorophyll-a. The results showed that for the three-band model, the maximum value for the coefficient of determination (R 2 ), of 0.88, was obtained using the λ 1 = 660 nm, λ 2 = 690 nm and λ 3 = 717 nm spectral bands. The model employing two spectral bands presented the best performance (R 2 = 0.87) in the λ 1 = 660 nm and λ 2 = 690 nm bands. An absolute mean error of 5.35 and 5.00 μg L -1 was found for the three-and two-band models respectively. The developed models are reliable, showing that chlorophyll-a concentrations can be quantified from remote-sensing field data with a high degree of accuracy.

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

Cited by 10 publications

References 2 publications

Dinâmica limnológica em reservatório artificial e rio intermitente na região semiárida em função do uso e ocupação do solo

Dinâmica limnológica em reservatório artificial e rio intermitente na região semiárida em função do uso e ocupação do solo

Chlorophyll-a prediction in tropical reservoirs as a function of hydroclimatic variability and water quality

Modelling chlorophyll-a concentrations in a continental aquatic ecosystem of the Brazilian semi-arid region based on remote sensing

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