Influence of urban and agricultural land use on trace metal contamination in the Rio do Campo watershed, Paraná, Brazil

This study evaluated the water quality of the Rio do Campo watershed, located in the municipality of Campo Mourão, Paraná State, through the analysis of physicochemical parameters and the quantification of total concentrations of trace metals (Cu, Zn, Mn, and Fe) using atomic spectrometry procedures following the Standard Methods for the Examination of Water and Wastewater (24th ed.). Sampling was carried out at five points with different land uses and occupations, in urban and rural areas, over a 6-month period. Data were summarized using median values and analyzed using non-parametric statistical approaches. The results indicated statistically significant differences between rural and urban areas, with higher trace metal concentrations and turbidity at urban sites, attributed to the input of effluents and increased surface runoff. Parameters such as pH, BOD, COD, and DO exhibited variation consistent with the land-use gradient. Principal component analysis revealed overlap among rural, urban, and intermediate sites, indicating the presence of a continuous environmental gradient along the basin. All concentrations remained within the limits established by CONAMA Resolution No. 357/(Tundisi 2005). Nevertheless, the observed spatial distribution reinforces that the system is sensitive to local anthropogenic pressures, particularly in urbanized sections, highlighting the need for continuous monitoring to prevent potential future changes in water quality.