Microbial, physical and chemical properties of irrigation water in rice fields of Southern Brazil

Abstract

This paper presents the results of the statistical analysis of microbiological, physical and chemical parameters related to the quality of the water used in rice fi elds in Southern Brazil. Data were collected during three consecutive crop years, within structure of a comprehensive monitoring program. The indicators used were: potential hydrogen, electrical conductivity, turbidity, nitrogen, phosphorus, potassium, calcium, total and fecal coliforms. Principal Component and Discriminant Analysis showed consistent differences between the water irrigation and drainage, as the temporal variation demonstrated a clear reduction in the concentration of most of the variables analyzed. The pattern of this reduction is not the same in the two regions -that is, the importance of each of the different variables in the observed differentiation is modifi ed in two locations. These results suggested that the variations in the water quality utilized for rice irrigation was infl uenced by certain specifi c aspects of each rice region in South Brazilian -such as anthropic action or soil/climate conditions in each hydrographic basin.

Environmental factors are the major drivers of macroinvertebrate assemblage structure in southern Brazilian coastal lakes

“…Although rice cultivation in the lakes’ surroundings predominates along the entire coast, this influence is greater in lakes further south (Marchett et al., 2013; Pereira et al., 2009), which may have resulted in higher values of conductivity and nitrate, and lower values of transparency in the water. In addition to being indirectly affected by the use of pesticides, macroinvertebrates in these lakes are also subject to hydric stress caused by water drainage for rice fields irrigation (Reche et al., 2016; Stenert et al., 2018).…”