Alpine areas in North-Western Italy are subject to elevate deposition of atmospheric pollutants. Chemical investigations on high-altitude lakes showed recovery from acidification for most of them; though, they are still affected by the deposition of pollutants from the atmosphere, especially of heavy metals. This study compares the concentrations of heavy metals in the alpine lake waters with those found in atmospheric depositions, to identify the possible contribution of deposition inputs to surface water ecosystems. The Visual MINTEQ model was used to calculate the equilibrium composition of dilute aqueous and precipitated compounds in freshwater. This model is the Windows version of the MINTEQA2 model (Allison et al., 1991; Allison and Brown, 1995), developed from the US-EPA. The model was applied to long-term chemical data of selected alpine lakes, to calculate aluminium speciation and to simulate its change in response to gradual modifications in a unit of pH. The ultimate aim of the modelling was to evaluate the possible threat to aquatic organisms of these highly toxic compounds. It was also applicated the Visual MINTEQ model to the experimental data of two lakes, covering three decades, in order to calculate the relative aluminium speciation in this lake water and to simulate the changes in Al species occurrence at various pH levels (such as occurs in late spring at snowmelt, which produces the largest contributions of annual weathering). At last, it has been analized the concentrations of some metals in freshwater of 13 alpine lakes located in the Ossola valley (aluminium, arsenic, cadmium, chrome, iron, manganese, lead, copper, selenium and zinc) and it has been investigated, in particular, the temporal trend of the single metals during the last ten years thanks a comparison with the crustal enrichment factor from sediment cores (Camarero et al., 2009).
Heavy metals and trace elements in alpine lakes (north-western Italy): origins and possible speciations in response to a gradual variation of pH
2011
Abstract
Alpine areas in North-Western Italy are subject to elevate deposition of atmospheric pollutants. Chemical investigations on high-altitude lakes showed recovery from acidification for most of them; though, they are still affected by the deposition of pollutants from the atmosphere, especially of heavy metals. This study compares the concentrations of heavy metals in the alpine lake waters with those found in atmospheric depositions, to identify the possible contribution of deposition inputs to surface water ecosystems. The Visual MINTEQ model was used to calculate the equilibrium composition of dilute aqueous and precipitated compounds in freshwater. This model is the Windows version of the MINTEQA2 model (Allison et al., 1991; Allison and Brown, 1995), developed from the US-EPA. The model was applied to long-term chemical data of selected alpine lakes, to calculate aluminium speciation and to simulate its change in response to gradual modifications in a unit of pH. The ultimate aim of the modelling was to evaluate the possible threat to aquatic organisms of these highly toxic compounds. It was also applicated the Visual MINTEQ model to the experimental data of two lakes, covering three decades, in order to calculate the relative aluminium speciation in this lake water and to simulate the changes in Al species occurrence at various pH levels (such as occurs in late spring at snowmelt, which produces the largest contributions of annual weathering). At last, it has been analized the concentrations of some metals in freshwater of 13 alpine lakes located in the Ossola valley (aluminium, arsenic, cadmium, chrome, iron, manganese, lead, copper, selenium and zinc) and it has been investigated, in particular, the temporal trend of the single metals during the last ten years thanks a comparison with the crustal enrichment factor from sediment cores (Camarero et al., 2009).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
