ABSTRACT
Agricultural production is the practice that uses the most water on the planet, especially the irrigated agriculture, which represents a large part of this demand. As well as the quantitative issue, adequate quality is essential to meet the demands of the crop and its return to the water sources, in a way that does not cause damage to the environment. To measure this consumption, the expression "water footprint" emerged. The water footprint seeks to quantify the demand for water incorporated into products. This paper aims to determine the amount of water used to produce irrigated rice in six rice growing regions in the state of Rio Grande do Sul (RS), in the 2019/2020 crop. The mentioned regions are represented the municipalities of Uruguaiana (West Border), Dom Pedrito (Campanha), Santa Maria (Central Region), Camaquã (Internal Coastal Plain), Porto Alegre (External Coastal Plain), and Rio Grande (South Zone). Climate data from the analyzed regions, during the plant cycle, and productivity values in the crop in question were used. Values of 1187 m3 t-1 were found for WB, 1347 m3 t-1 for CA, 1058 m3 t-1 for CR, 783 m3 t-1 for ICP, 1115 m3 t-1 for ECP, and 1066 m3 t-1 for SZ. For the state of Rio Grande do Sul, an average water footprint was obtained in the 2019/2020 crop of 1093 m3 t-1.
Subject(s)
Oryza , Water , Environmental Monitoring , Brazil , AgricultureABSTRACT
RESUMO Neste estudo foram avaliados os efeitos do tamanho da partícula e de variações da concentração de sedimentos suspensos (CSS) sobre as leituras de turbidez de três sensores óptico-nefelométricos, com iguais características ópticas e geométricas, utilizando amostras de sedimentos suspensos coletadas na seção fluviométrica da bacia do Turcato (19,5 km²), localizada na Região Sul do Brasil. O material coletado passou por processos de peneiramento e pipetagem para fracionamento nas granulometrias areia e silte. Para cada diâmetro foram separadas frações com diferentes concentrações de sedimentos, variando entre 0,01 e 5,00 g.L-1. Os resultados demonstram grande influência da CSS e do tamanho da partícula sobre a turbidez. Para qualquer situação, o aumento da turbidez é inverso ao tamanho da partícula e diretamente relacionado ao aumento da CSS. As variações da turbidez, expressas em função da CSS (sensibilidade do sensor), são maiores para menores diâmetros, atingindo valores quase constantes para partículas de areia. As leituras de turbidez dos três sensores não apresentaram diferença significativa no nível de 5% pelo teste de Mann-Whitney rank sum . Para uma mesma CSS, a leitura de turbidez pode ser diferente, conforme a classe granulométrica analisada. A turbidez registrada pelo sensor para a classe silte equivale a uma turbidez observada para uma CSS dez vezes menor para a classe das areias.
ABSTRACT This study evaluates the effects of particle size and variations of CSS on turbidity readings of three optical-nephelometric sensors using sediment samples collected in the field. Samples were collected in fluviometric station at Turcato basin (19.5 km²), located in the South region of Brazil. The collected material underwent screening and pipetting processes for fractionation in sand and silt grain size. For each diameter were separated fractions with different sediment concentration ranging between 0.01 and 5.00 g.L-1. The results demonstrate great influence of CSS and particle size on turbidity readings. The increase in turbidity is opposite to particle size and directly related to CSS. Variations in turbidity, expressed in CSS function (sensor sensitivity), are higher for smaller diameters, reaching almost constant values for sand particles. Turbidity readings of the three sensors showed no significant difference in the level of 5% by the Mann-Whitney rank sum test. For a given CSS, the turbidity reading may be different, depending on the granulometric class analyzed. Turbidity recorded by the sensor to the silt-class is equivalent to a sensor response observed for a CSS ten times lower for the sand class.