**5. La Ciénaga Grande de Santa Marta**

This physiography comprises the eastern sector of the great delta of the Magdalena River and extends between the same river and the Ciénaga Grande de Santa Marta and up to the foothills of the Sierra Nevada de Santa Marta. On the other hand, this region extends from the Caribbean Sea on the Island of Salamanca, to the Caño Ciego, which later flows into the Fundación River, taking before flowing into it, the name of Caño Schiller.

#### **Figure 5.**

*(A) Location of the sampling stations in the Ciénaga Grande de Santa Marta. (B) Average content and standard deviation of total mercury (μg Hg g−1 d.w.) in sediments of the Ciénaga Grande de Santa Marta (four seasons), between March and October 1996. 1. Islas del Rosario. 2. Boca de Caño Grande, 3. Centro, 4. Boca del Río Sevilla. Modified from Alonso et al. [7].*

In the REDCAM program [10], six stations were included in the area of influence of the CGSM, apparently, they were only measured in the dry season and the contents fluctuated between 8.0 and 89.4 ng Hg g−1 d.w. The maximum value was measured in front of the mouth of the Sevilla River in the central part of the eastern side (**Figure 5A** Station 4), which drains from the SNSM, followed by the sediments collected near the mouth of the Fundación River, which, in addition to being born in the SNSM, receives the discharges of the Magdalena River, followed by the concentrations determined in sediments from other rivers of the SNSM fluvial system.

According to Alonso *et al*. [7], the Hg content in sediments fluctuated between 20 and 109 μg Hg g−1 d.w., with an average value of 58±6. These values are close to natural values (**Figure 5**). Although the authors did not determine significant differences, a slightly greater influence on Hg discharge is observed at the mouth of the Sevilla River, which belongs to the SNSM water system, which is consistent with the REDCAM results.
