Howard 2006). Even if the substances are not particularly persistent in the environment as much as POPs (e.g. PCBs), the use of some of them in large amounts
(e.g. in agriculture) may result in a steady transport to the mountains and the
exposition of the organisms there to high concentrations (Weber et al. 2010).
Metals are other atmospheric pollutants that have accumulated in the mountains
(Camarero 2017b). In fact, they have a longer history than POPs. Evidence of early
pollution in Europe dating from the Roman period and also from ancient times in
other parts of the world becomes stronger the more studies on natural registers exist
(Catalan 2015). Mountains have also been sites of historical interest for mining
provided that ores of different minerals are common. Depending on the economic
context even the exploitation of small, difficult to access mines have taken place
(e.g. Trou des Romains, Val Sapin, Italian Alps). The regional context of this
mining throughout history is well recorded in lacustrine sediments and peats
(Camarero et al. 1998). The ecological consequences, if any, of these atmospheric
pollutants have not been evaluated yet. In some areas, the accumulation of some
trace metals in soils is very high so, under lower current deposition, they have
become sources of pollutants to sediments, plants, and animals, rather than sinks
(Bacardit et al. 2012). There is a legacy of pollutants in soils that may maintain high
pollutant fluxes for some decades.
Ozone depicts a unique case in the global change context. On the one hand, the
current decline in stratospheric ozone causes an increase in the UV radiation
reaching the ground. In high mountains, the effect is enhanced compared to low
lands. First, because the atmosphere is thinner and thus both total and relative UV is
higher (Blumthaler et al. 1997); second because many high mountains are above a
cloud belt that protects valley lands from high radiation (Blumthaler et al. 1994).
However, the direct consequences for the organisms’ life of the increase in UV and,
particularly, in the more harmful UVB, might not be huge, since mountain
organisms have evolved in high UV environments, thus have developed many
protective and repairing mechanisms. Nevertheless, UV exposure is repeatedly
pointed as a potential factor of some species decline (Mitchell et al. 2015). On the
other hand, tropospheric ozone is increasing. At ground level, ozone protective role
against UV matters little and what becomes important is its harmful highly
oxidative effect (Wittig et al. 2009). Observatories in high mountains have indicated
a sustained increase in tropospheric ozone in many areas of the world. It can be
considered a global hazard. Indeed, there are mountains particularly exposed to air
masses that bring high ozone concentrations from source areas (Elvira et al. 2016).
Ozone is harmful both to plants and humans. The effects of ozone on trees may be
confounded at first instance with drought effects. It would be reasonable to develop
specific surveillance protocols for high mountains, particularly in nature reserves.
Thus environmental assessment will provide a double benefit. With climate change,
the stratosphere-to-troposphere ozone flux will be modified with latitudinal differences in UV radiation effects and stratospheric ozone (Hegglin and Shepherd 2009).
Some technically sophisticated observatories already deal with estimations of trends
and global averages (Li et al. 2007; Cristofanelli and Bonasoni 2009; Cristofanelli
et al. 2010). Simpler systems may serve as sentinels for conservation purposes,
8
J. Catalan et al.
(e.g. in agriculture) may result in a steady transport to the mountains and the
exposition of the organisms there to high concentrations (Weber et al. 2010).
Metals are other atmospheric pollutants that have accumulated in the mountains
(Camarero 2017b). In fact, they have a longer history than POPs. Evidence of early
pollution in Europe dating from the Roman period and also from ancient times in
other parts of the world becomes stronger the more studies on natural registers exist
(Catalan 2015). Mountains have also been sites of historical interest for mining
provided that ores of different minerals are common. Depending on the economic
context even the exploitation of small, difficult to access mines have taken place
(e.g. Trou des Romains, Val Sapin, Italian Alps). The regional context of this
mining throughout history is well recorded in lacustrine sediments and peats
(Camarero et al. 1998). The ecological consequences, if any, of these atmospheric
pollutants have not been evaluated yet. In some areas, the accumulation of some
trace metals in soils is very high so, under lower current deposition, they have
become sources of pollutants to sediments, plants, and animals, rather than sinks
(Bacardit et al. 2012). There is a legacy of pollutants in soils that may maintain high
pollutant fluxes for some decades.
Ozone depicts a unique case in the global change context. On the one hand, the
current decline in stratospheric ozone causes an increase in the UV radiation
reaching the ground. In high mountains, the effect is enhanced compared to low
lands. First, because the atmosphere is thinner and thus both total and relative UV is
higher (Blumthaler et al. 1997); second because many high mountains are above a
cloud belt that protects valley lands from high radiation (Blumthaler et al. 1994).
However, the direct consequences for the organisms’ life of the increase in UV and,
particularly, in the more harmful UVB, might not be huge, since mountain
organisms have evolved in high UV environments, thus have developed many
protective and repairing mechanisms. Nevertheless, UV exposure is repeatedly
pointed as a potential factor of some species decline (Mitchell et al. 2015). On the
other hand, tropospheric ozone is increasing. At ground level, ozone protective role
against UV matters little and what becomes important is its harmful highly
oxidative effect (Wittig et al. 2009). Observatories in high mountains have indicated
a sustained increase in tropospheric ozone in many areas of the world. It can be
considered a global hazard. Indeed, there are mountains particularly exposed to air
masses that bring high ozone concentrations from source areas (Elvira et al. 2016).
Ozone is harmful both to plants and humans. The effects of ozone on trees may be
confounded at first instance with drought effects. It would be reasonable to develop
specific surveillance protocols for high mountains, particularly in nature reserves.
Thus environmental assessment will provide a double benefit. With climate change,
the stratosphere-to-troposphere ozone flux will be modified with latitudinal differences in UV radiation effects and stratospheric ozone (Hegglin and Shepherd 2009).
Some technically sophisticated observatories already deal with estimations of trends
and global averages (Li et al. 2007; Cristofanelli and Bonasoni 2009; Cristofanelli
et al. 2010). Simpler systems may serve as sentinels for conservation purposes,
8
J. Catalan et al.