Microbiological and physical–chemical water quality of the rice fields in Sinos River’s basin, Southern Brazil

Abstract

In this study, we evaluate spatial and temporal variations of the water's quality used in rice fields. Every 15 days during the different phases of cultivation of the rice-vegetative, reproductive, and maturity-samples were collected from the main irrigation channel, from the surface water in the field, and from the excess-water drainage channel. The differences in the values of 13 variables were analyzed by the analysis of variance system and by the Principal Component Analysis (PCA) technique. The results demonstrate that the values observed for the presence of total coliforms, heat-tolerant coliforms, and pH were higher in the irrigation water and that the calcium and magnesium components were greater in the drainage water. The PCA results indicate that three groups of variance exist and that these three account for 77 % of the observed variances. The first principal component, (39 % of the variances), includes the variables pH, phosphorus, potassium, carbon, and turbidity; the second (28.1 %), calcium, magnesium, and conductivity; while the third accounts for only 9.9 % of the variation and incorporates the variable biological thermotolerant coliforms. The spatial pattern resulting from the distribution of the sampling locations as regards the first two principal components indicates a difference between the irrigation and drainage waters. The variables of the first and third items (except for the turbidity in the second component) reach higher values in the irrigation water, while the variables associated with the second component have higher values in the drainage water. The information provided is important for the analysis of the influence exercised by plantation management decisions on the microbiological, physical, and chemical quality of the water. The results confirm the ability of paddy rice field to filter out some of the chemicals and coliforms from the irrigation water as it passes through the agro ecosystem.

Freshwater parameters in the state of Rio Grande do Sul, southern Brazil, and their influence on fish distribution and aquaculture

“…, presented low levels in Rio Grande do Sul (Diel et al, 2007;Kochhann et al, 2013;Panizzon et al, 2013), in accordance with the mean low water hardness noted in this study.…”

“…Low turbidity values (3-97 NTU) were also observed in other studies of rivers in this state (Petry & Schulz, 2006;Salomoni et al, 2006;König et al, 2008;Blume et al, 2010;Pimenta et al, 2012;Panizzon et al, 2013). High turbidity is associated with a lack of marginal vegetation and deforested areas that favor runoff of sediment during rainy periods (Wachholz et al, 2011;Mattos et al, 2014).…”

Benthic macroinvertebrates in Italian rice fields

“…The shortage of the period of water permanence can affect the survival of species with longer cycle (Bazzanti et al, 2003;Caramujo and Boavida, 2010). Water in rice fields is also subject to quick physical and chemical changes (Panizzon et al, 2012). Thermal fluctuations are directly affected by the height of rice plants, with the consequent creation of a microclimate with aspects of tropical and subtropical areas with small thermal excursions also at northern latitude (Confalonieri et al, 2005).…”

Microbial Diversity: Relevance and Relationship Between Environmental Conservation And Human Health

“…Rice cultivation in Brazil is primarily in irrigated mode. The largest producing state of Brazil is Rio Grande do Sul with 1,0666 million hectares, representing 44.5% of the national area and accounting for 66.5% of Brazilian production (Panizzon et al 2013 …”