Campaign #6

On Monday 14 October, we headed out to the field for the first day of the sixth campaign. By now, the experience of the previous campaigns came in handy to access the selected sampling sites and organise the logistics of the field visits. The dry season has had a clear impact on the water levels in the rivers, while the reservoirs were reaching an all time low due to the unprecedented drought. In the end, 51 accessible sites were selected: 30 river/stream sites and 21 reservoir sites.

We collected information on the abiotic conditions in each of the 51 sampling sites. To get this data, we made use of a multiprobe (a device that measures several conditions at once) on-site and USEPA approved test kits to determine the nutrient concentrations off-site. The collection of this data confirmed the patterns of the previous campaigns and are in line with what we expected. For instance, ammonium and nitrite concentrations directly downstream of the city of Cuenca (site CU03, followed by CU02 and PA01) were higher than all previous campaigns and almost two to five times higher than what we observed in July/August 2024. Also orthophosphate concentrations were clearly higher than before. It is not unthinkable that the extreme drought played a role in these excessive nutrient levels. Equally interesting is the decreasing nutrient levels in the downstream direction, which shows that the Paute river system is able to recover from a signicant pollution event.

A total of 51 sampling sites were selected and assessed for a variety of water quality parameters. The abiotic conditions showed a clear similarity with the previous campaigns, with clearly higher nutrient levels directly downstream of the city of Cuenca.

More information can be found in the short report on the sixth sampling campaign [link].

We would like to thank D.M. Siguencia Calle and D.J. Vimos Loja for their help in collecting the samples in the field as well as their subsequent processing in the lab. We also thank D.G. Zuñiga Villegas for providing us with the necessary transport.