Depth Profile Of Trace Elements In a Sediment Core Of a High-Altitude Lake Deposit At The Pyrenees, Spain

Abstract

Depth concentration profiles of 26 elements, i.e. trace elements (As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb, Rb, Sr, V and Zn), lithophiles (Si, Al, Fe, Mn, Na, K, Mg, Ca and Ti) and nutrients (C, P, N, S) have been established in a sediment core collected at the Respomuso Lake (Pyrenees, Spain). This high altitude lake of glacier origin was transformed into reservoir in the fifties of last century. Correlations among the depth profiles of the above elements were established. HCl-extractable elements, which are better related to bioavailability, followed the profiles of total contents. Principal component analysis was applied to establish the binding behaviour of trace elements in the sediment matrix and, in turn, to search for their anthropogenic or natural sources. It was seen that Cu, Ni, Pb, Sr and Zn clustered together, and with exception of Sr, they were not clearly associated with any major component of the sediment. Their depth profiles correlate well with each other, hence indicating their presence as a result of atmospheric pollution. Redox-sensitive elements such as Fe and Mn follow a similar trend along the vertical profile. Depth profiles of As an Co correlate well with those of Fe and Mn. Principal component analysis showed that As, Co, Fe and Mn clustered together, which confirms the close association of As and Co with Fe-Mn oxyhydroxides. As concentrations in many strata exceed the ERM value, and therefore, significant biological effects are expected. Dissolution of minerals such as pyrite, chalcopyrite and galena taking part in the mineralogy of this area accounts for the As concentration found. Ba, Cr, Rb and V were associated with the sediment matrix (aluminosilicates), hence showing low mobility.

Climate change enhances the mobilisation of naturally occurring metals in high altitude environments

“…This is consistent with the averaged sediment deposition rate of 1.5 cm year -1 for the core extracted from upper Lake Respomuso (Lavilla et al, 2006) (Figure 1), and also with the relatively low depositional rates reported for other Pyrenean reservoirs (ValeroGarces et al, 1999). It also corresponded to the sedimentation laminae along the profile, likely produced during spring thaw, which implies sediments were not disturbed by mixing.…”

On the arsenic source mobilisation and its natural enrichment in the sediments of a high mountain cirque in the Pyrenees

“…4a). Furthermore, a sediment core extracted in 2002 from Respomuso Lake bed had HQ ¼ 1.9 in the <5 cm sediment depth (see also Lavilla et al 13 ). This might indicate a relatively substantial background risk to benthic biota from arsenic.…”

“…in the Central Pyrenees. 12 Likewise lake bottom sediment concentrations as high as 339 mg As kg À1 were reported for Lake Respomuso at an altitude of 2130 m. 13 This is a very high level of As which exceeds most sediment quality criteria for the protection of aquatic life and can have potentially deleterious effects on the aquatic resources as well as the wider environment. 2 The burden of As in remote high altitude water bodies may arise from geogenic and atmospheric sources (e.g.…”

Non-residual Sr of the sediments in Daihai Lake as a good indicator of chemical weathering

“…The non-residual Rb and Sr contents in the sediment samples were obtained upon extraction with 1 M HCl according to the procedure recommended by the ASTM D3974-81 Practice B (Snape et al, 2004 Lavilla et al, 2006). This standard practice indicates that the metals released from the sediment upon acid extraction are bound as hydroxides, carbonates, sulphides, oxides and organic materials.…”