Abstract
Watersheds are defined as a set of lands where water drainage occurs through rivers and their tributaries. A large quantity of water resources exist in the state of Maranhão, Brazil, where rivers and their basins must meet environmental quality standards defined by the limits set out in national environmental council (CONAMA) legislation 357/05 for physicochemical and microbiological parameters, including parasites. Multivariate statistical techniques were applied to study the temporal and spatial variations in water quality of a segment of the Pindaré River. The data set included nine parameters for three sampling points over eleven months. Principal component analysis grouped the monitored sampling points into four clusters and identified electrical conductivity, temperature, total dissolved solids (TDS), pH, salinity, and Escherichia coli as being associated with the dry season and nitrite, nitrate, and turbidity as being associated with the rainy season. Three principal components explained 83.80% of the data variance during the rainy and dry seasons. The evaluated correlations indicated that during the rainy season, nitrite (~0.18 mg L−1) and turbidity (~46.00 NTU) levels were the highest, but pH was at its lowest (~6.61). During the dry season, TDS (~155.00 mg L−1) and pH (~8.10) were highest, and E. coli bacteria was more abundant.
Highlights
Rivers are formed by natural water sources that are liable to biological, chemical, and anthropological influences, and yet river water often represents a source for human water supply
principal component analysis (PCA) was applied to the experimental data in order to visualize the differences among the samples, and the results were analyzed using the Minitab
In consideration of physiochemical parameters and microbiological parameters during dry and rainy periods, where for the means different at each point (P1, P2 and P3), different letters (a, b and c) were attributed, so that at the points where the means have equal letters, it can be stated that there was no statistical difference between the data observed
Summary
Rivers are formed by natural water sources that are liable to biological, chemical, and anthropological influences, and yet river water often represents a source for human water supply. Such influencing factors allow us to understand the importance of water for our bodies and especially in our cells [1]. Water 2020, 12, 851 quantity of water resources exist in the state of Maranhão, Brazil, which cover an area of 325,650 km and can be distinguished as subterranean waters, watersheds, and lacustrine basins [3]. The Pindaré River basin covers an area of ~36,680 km , a large part of which is within the state of Maranhã. The water quality of the rivers and the wider basin depends on factors related to water preservation; there should be a periodic water quality control assessment to indicate the existence of pollution [5]
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