Trace elements biogeochemistry in high mountain lake catchments: identifying anthropogenic versus natural components from the atmospheric contamination legacy in remote natural areas

Abstract

Human activities have been interfering with the natural biogeochemical cycles of trace elements since the ancient civilizations. Although they are inaccessible and remote, high mountain lake catchments are irrefutably trace-element contaminated by anthropogenic emissions, which can travel by long-range atmospheric transport before they are deposited. This has been revealed by several natural archives. High mountain lake catchments are thus excellent sentinels of long-range contamination. Continuous accumulation can lead to a build up of potentially toxic trace elements in these remote, or relatively remote, ecosystems. The thesis focuses on the biogeochemistry of a suite of trace elements of environmental concern (Ni, Cu, Zn, As, Se, Cd and Pb) in Pyrenean lake catchments, with special emphasis on discerning the “natural” components from the “anthropogenic” contributions. Five other metallic elements (Al, Fe, Ti, Mn and Zr) have also been studied to trace natural fluxes and biogeochemical processes within the lake catchment systems.

Les activitats humanes han interferit en els cicles biogeoquímics naturals dels elements traça des de les antigues civilitzacions. Malgrat ser inaccessibles i remotes, les conques lacustres de muntanya es troben clarament contaminades pels elements traça procedents d’emissions antropogèniques, que s’hi han desplaçat per mitjà del transport atmosfèric de llarg abast i la subseqüent deposició, tal com revelen diversos arxius naturals. Per tant, les conques lacustres de muntanya són indicadores excel•lents d’aquesta contaminació de llarg abast. La seva contínua acumulació ha deixat una quantitat important d’elements traça potencialment tòxics en aquests ecosistemes remots o relativament remots. La tesi se centra en la biogeoquímica d’un conjunt d’elements traça de rellevància ambiental (Ni, Cu, Zn, As, Se, Cd i Pb) en conques lacustres pirinenques, amb especial èmfasi en distingir els components “naturals” de les contribucions “antropogèniques”. A més a més, s’han estudiat cinc metalls més (Al, Fe, Ti, Mn, Zr) per traçar fluxos i processos biogeoquímics naturals en els sistemes lacustres.