**3.1 Heavy metals, texture, and organic matter in sediments**

The results of heavy metals are shown in **Table 3** during the dry (1) and rainy (2) climatic seasons. These results confirm that Fe is one of the most abundant elements during the dry season (216.03–224.75 μg/g), suggesting evaporation phenomena and low sediment mobility. During the rainy season, the values decrease considerably (12.90–34.60 μg/g). During the dry season, the Mg (14.93–17.91 μg/g) did not show significant variations. In the rainy season (5.18–24.20 μg/g) the behavior pattern shows variations by the site. The Mn presents variations in both climatic seasons: dry season (6.89–13.44 μg/g), and rainy season (2.77–15.09 μg/g). Cu and Cd do not show a variable behavior. Although it is very difficult to differentiate between anthropogenic and natural contributions, the variations that occur during the climatic seasons; are an important element for contamination analysis.

The highest Cd values were in the rainy season at the "Laguna del Este" site with 2.34 μg/g. For Mg, the highest values occurred during the rainy season at the "El


#### **Table 3.**

*Levels of heavy metals during the two climatic seasons: dry (1) and rainy (2) in μg/g.*


