The headwaters of the Río Huicha, Chiloé (Chile)

Successful rejection of a planned landfill.

Leachates, which are a toxic mixture of chemical compounds and rainwater, are formed in landfills of household and industrial waste, particularly in areas of high precipitation. These leachates can, despite the presence of landfill linings, directly affect groundwater quality and, consequently, have negative long-term impacts on the health of human populations as well as a detrimental effect on aquatic ecosystems 1-5. Studies have shown that certain substances in leachates such as surfactants affect the polymere bonds within HDPE membranes, making them brittle and permeable over time1. Moreover, organochlorines that are common in leachates, diffuse through HDPE membranes of varying thickness6,7. These substances bioaccumulate in cell tissues and can cause serious long-term health effects.
Uncontaminated river systems are characterized by hundreds of different species 8 that are functionally linked and interconnected in complex trophic networks 8-11. Subsurface springs and runoff from Aquands (Ñadi soils) as well as groundwater feed the river catchment of the Río Huicha and other rivers in the north of Chiloé. This catchment together with other large river networks such as those of the river Puntra and Chepu are the few fluvial ecosystems in Chiloé with an intact link between wetlands and the native Valdivean rainforest, characterized by a high aquatic biodiversity (hotspots). Results obtained by analysing just five different aquatic systems in the headwater region of the Huicha catchment in August 2019 reveal the presence of 406 benthic protist and invertebrate species, a biodiversity that is far higher than that of any other river system previously studied in Chile 12. Our findings underline that these stream systems are unique and pristine sites with dozens of new species for science and 199 new records for Chile . These species are important links within these complex fluvial food-webs 9-11 and serve as energy source for rare and endagered fish, amphibian, bird and mammal species.

Selected scientific publications

1. Sangam, H.P. & Rowe, R.K. 2001. Geotextiles and Geomembranes 19, 329.
2. Öman, C., Hynning, P.A. 1993. Environmental Pollution 80, 265.
3. Öman, C. & Rosqvist, H. 1999. Water Research 33, 2247.
4. Kjelsen, P. et al. 2002. Critical Reviews in Environmental Science and Technology 32, 297.
5. Öman, C. & Junestedt, C. 2008. Waste Management 28, 1876.
6. Müller, W. W. 2007. HDPE geomembranes in geotechnics., Springer Verlag, Heidelberg, Germany, pp.485.
7. Müller, W. W. 2009. Dichtungsbahnen zur Abdichtung von Deponien und Altlasten. en: Fachtagung "Die sichere Deponie 2009 – Abdichtung von Deponien und Altlasten mit Kunststoffen" Veranstalter: SKZ - ConSem GmbH, Würzburg und AK GWS Arbeitskreis Grundwasserschutz e. V, Berlin, 1.
8. Schmid, P.E. et al. 2000. Science 289, 1557.
9. Schmid-Araya, J.M. et al. 2002. J. Anim. Ecol. 71, 1056.
10. Schmid-Araya, J.M. et al. 2011. Austral Ecology 37, 440.
11. Schmid-Araya, J.M. et al. 2016. Ecology 97, 3099.
12. Schmid, P.E. & Schmid-Araya, J.M. in prep.