Data di Pubblicazione:
2016
Abstract:
Based on long-term trends of water chemistry parameters of photochemical significance from four lakes located
in the Alps (Iseo, Garda, Piburgersee, Geneva), we calculated the corresponding steady-state concentrations of
photoinduced transient species with an ad-hoc photochemical model. Such transients were the hydroxyl (•OH)
and carbonate (CO3
−•) radicals, singlet oxygen (1O2), and the triplet states of chromophoric dissolved organic
matter (3CDOM*). Among the investigated lakes, Lake Iseo, for example, showed a long-term near-stability in
chemical parameters that resulted in a photochemical stability. By contrast, Piburgersee underwent important
chemical modifications, but the interplay of compensation (parallel increase of both inorganic and organic
carbon) and near-saturation effects (organic matter as main •OH source and sink) prevented the modelled photochemistry
to undergo significant shifts over time. This result suggests the occurrence of a sort of “photochemical
buffering” in some lake ecosystems, which would dampen modifications of the steady-state concentration of
the photochemically-formed reactive transients, even in the case of significant changes inwater chemistry. Finally,
in lakes Garda and Geneva, long-term changes in water chemistry had an effect on photochemistry. While in
Lake Garda the small increase in DOMwas associated to a small increase in 1O2 and 3CDOM*, in Lake Geneva, the
increases in pH and bicarbonate and the decrease in nitrite resulted in an •OH decrease. Overall, our results predict very different lake photochemistry patterns in relation to alterations in water chemistry parameters
caused by climate change, such as changes in water alkalinity and dissolved organic carbon concentration.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
Minella, Marco; Leoni, Barbara; Salmaso, Nico; Savoye, Liliane; Sommaruga, Ruben; Vione, Davide
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