Atmospheric Chemical Loadings in the High Mountain: Current Forcing and Legacy Pollution

Abstract

Human emissions have changed the chemistry of atmosphere. Potentially toxic chemicals have been spread, and the global cycles of some key elements have been disrupted. Because enhanced atmospheric precipitation and cold trapping caused by elevation, high mountain ecosystems are considered as regional convergence areas of atmospheric pollutants. In this chapter, research on surface waters acidification, pollution by trace elements, and atmospheric nutrient inputs in the Pyrenees is reviewed. Pyrenean lakes have experienced only a moderate acidification, due partly to an also moderate acid load and partly to the neutralising cations carried by dust. Presently, declining concentrations of sulphate in lakes indicate that recovery is proceeding. Pollution by trace elements dates more than two millennia back. The primary accumulation sites are the sediments of lakes. Soils also hold an important burden, and there is evidence that some elements are being currently remobilised. This is causing a delayed pollution, despite deposition of several trace metals is declining. The emissions of artificial reactive nitrogen have caused increased deposition on the Pyrenean catchments, which are thus nitrogen saturated. A parallel increase of phosphorus deposition has occurred, likely caused by climatic reasons. The combined effect of both seems to be an enhanced uptake of nitrogen by phytoplankton causing a lower nitrogen concentration in lakes and a possible shift from phosphorus-to-nitrogen limitation of phytoplankton growth, as well as an incipient eutrophication. All these are examples of impacts in remote natural areas that require a global strategy of conservation beyond the boundaries of the ecosystems affected.

The High Mountain Conservation in a Changing World

“…High mountain nature reserves are particularly suitable for developing long-term studies to investigate the development and consequences of global change on ecosystems. To cope with the local characteristics of the atmospheric forcing, meteorological and deposition stations have to be deployed and maintained with a perspective of at least decades, to provide fundamental information to any other ecosystem study in the mountain catchments (Camarero 2017b). Photography: Lluis Camarero mountains are experiencing a large cultural and socio-economical shift in many regions of the world (Ooi et al 2015).…”

“…Metals are other atmospheric pollutants that have accumulated in the mountains (Camarero 2017b). In fact, they have a longer history than POPs.…”

Trade-offs in High Mountain Conservation

“…In consequence, vegetation cover is reduced, leading to mutually reinforcing feedback (for instance, between vegetation cover, water retention and soil erosion). Also, high altitude favours the passage of pollutants from the troposphere to the ground (Camarero 2017b) and a loss of atmospheric protection against ionising radiation. Therefore, only relatively few species are able to persist in these extreme conditions.…”

“…The capacity of local managers to reduce exposure to these agents is very limited. For instance, high mountain lakes are particularly exposed to airborne chemical loadings (see Camarero 2017b), and in this case reducing the sensitivity of these ecosystems involves the preservation of biodiversity and food webs (Ventura et al 2017).…”

L’explotació dels territoris pirinencs orientals en època antiga (s. VI-I ane)

“…Cal recordar que hi ha mines de plata al Canigó (plom argentífer a les mines de Montboló, al sud del Canigó, en direcció vers el Coll d'Ares), al Pallars (Pb-Zn i galena per exemple a Cierco, Pont de Suert) i al Seronais (amb explotacions d'aquesta cronologia, com apareix en aquest mateix volum). De fet, els darrers estudis d'isòtops de plom a Lac Redon han identificat una contaminació diferenciada respecte d'un moment previ que estaria vinculada al coure i al plom argentífer (Galena), indicativa d'una activitat d'extracció minera i que coincidiria, per tant, amb el que ens indiquen les fonts literàries (Camarero, 2017;Pèlachs et alii, 2017). Sigui o no casual, és en aquest sentit destacable la localització a Llo, en nivells de Ferro I, d'un magnífic anell de ferro amb incrustacions de plata de gran nivell tècnic i que no deixa de sorprendre per la seva qualitat tècnica, indicativa d'un notable domini de les tècni-ques metal·lúrgiques de la plata (Queralt i Olesti, 2016).…”