Association patterns among physical, chemical and microbiological indicators of springs in Rio Grande do Sul, Brazil

Concern about the quality of water consumed by rural communities leads to caution regarding the interference of variables in potability. This study aimed to verify the linear association between physical, chemical and microbiological variables of water from springs. The research was developed from two seasons of spring water sample collections evaluating physical and chemical variables such as temperature, pH, turbidity, electrical conductivity total alkalinity, total hardness, total ammonia, nitrite, nitrate, true and apparent colors, total phosphorus, fluoride and total iron, and microbiological variables: total coliforms and Escherichia coli. The variablesʼ total alkalinity, total hardness and electrical conductivity have a strong positive correlation among them, similar to what occurs with the variablesʼ turbidity, apparent color, true color and total iron, between nitrite and total iron, and between turbidity and total coliforms. These correlations occur as a function of the interaction that water has with the soil and with the compounds found, thus altering the quality. Water sample collections occurred twice in the same year - 2019.Temperature and pH analyses (portable pHmeter pHEP®4 Hanna) were performed “in loco”. In the laboratory, the analysis and methods according to APHA et al. (2012) were: Turbidity (NTU), Electrical conductivity (µS/cm), Total alkalinity (mg/L CaCO3) and Total hardness (mg/L CaCO3), Total Ammonia (mg/L N-NH3) and Nitrate (mg/L N-NO3-), True and Apparent colors (HU), Nitrite (mg/L N-NO2-), Total phosphorus (P) (mg/L P), Fluoride (F-) (mg/L F-) and Total iron (Fe) (mg/L Fe), Total Coliforms and Escherichia coli (MPN-more probable number/100 mL).