Correlações entre os parâmetros físico-químicos de um corpo hídrico superficial localizado no semiárido cearense: a estatística multivariada como ferramenta

Abstract

Water is an indispensable substance for the existence of any organism, as its use becomes increasingly integrated into the economic sector, ranging from irrigation in crops to its application in industrial and domestic processes. It is a finite and vulnerable resource, crucial for life preservation, development promotion, and environmental sustainability. However, to ensure favorable conditions for humans, it is imperative to conduct checks on its quality, given that sanitary conditions are affected based on certain parameters. The quality of water varies primarily due to the nature of the soil, climatic conditions, and human factors, such as domestic discharge, especially from municipal and industrial effluents. In this context, the present study aims to monitor the physico-chemical parameters of Riacho Araibú, located in the semi-arid region of Ceará, and apply multivariate analysis methods for both current and historical variables at the same location and also for the parameters. The proposal is to analyze and then justify in a simplified and coherent manner among the results, considering joint analysis and understanding the behavior and influence of the parameters individually in each period. Collections for the analyses were conducted between April and August, with samples taken at a specific point distributed over these five months. The analyzed parameters include pH, electrical conductivity, total residues, and turbidity. In this context, multivariate statistical analysis is applied, using the Pearson correlation method, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) to assess water quality in three distinct periods. The objective is to identify the main groups and their correlations, justifying in a simplified and coherent manner the observed significant events, obtaining consistent results for each data over the years of analysis. In various situations, however, it was observed that the stream did not show significant changes, maintaining high pollution levels, water scarcity, and the presence of dissolved solids. Nevertheless, it was noted that temperatures are higher, accelerating processes and contributing to the decrease in water volume in the stream, eventually leading to its complete dryness.