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Centre for Earth and Environmental Science Research

Trace element dynamics in high atlitude glacial environments

Executive Summary
ResearchersD. Zaharescu
Prof. A.P. Soler (University of Vigo, Spain)
Dr P.S. Hooda, CEESR (Kingston University)
Funding Body/SourceUniversity of Vigo, Spain
DurationSept 2004 - Dec 2008
Project SummaryMain Aims and Objectives
The main objectives of the present study are to describe patterns in the landscape composition of high altitude lakes in the central Pyrenees at catchment, biological, physico-chemical, and chemical resolution and to identify and quantify the main natural and human threats (vulnerability), affecting these remote natural ecosystems. Knowledge of these aspects constitutes the foundation for understanding landscape processes in these pristine water bodies, and identification of indictors of stress or healthy functioning of such ecosystems will provide tools for global monitoring of such pristine environments.

The study is divided into two parts. Part I includes a regional description of 370 water bodies (lakes and ponds) distributed in the central part of the National Park of Pyrenees (France) and Tena Valley (Spain) and the identification of lakes diversity and typology. This has been developed in three chapters: 1. Bedrock geology and catchment patterns (macrocosms) including environments and corridors related with these water bodies (mezocosms), 2. Physico-chemical patterns of lakes, water and sediments (temperature, conductivity, dissolved oxygen, pH), 3. Biotic patterns: zoobenthos and vertebrate assemblages in lakes, aquatic and riparian macrophites.

In Part II the vulnerability is discussed in four chapters. In the first chapter, the case of trace metals distribution and contamination in sediment and water in the lakes and their catchment streams. 2. The case of arsenic and other trace elements contamination and sources in Respomuso reservoir catchment is discussed at a complete catchment scale. 3. The historical record of contamination with arsenic and other trace elements in two reservoirs in Tena Valley (Respomuso and Bubal) is viewed from an upstream- downstream connectivity perspective.

In the final chapter vulnerability is regarded as salmonid stockings in the National Park of Pyrenees and its impact on local amphibians, zoobenthos communities, and physico-chemical parameters.

A conservation and educational plan regarding threats to mountain lakes is proposed

Publications

Zaharescu D, Hooda P, Palanca SA, Fernandez FJ (2007). An investigation of arsenic and other trace elements in Lake Respomuso and its catchment area. In Abstracts, 30th Congress of the International Association of Theoretical and Applied Limnology, Montreal, August 12-18, 2007, F:\docs\2178.htm. SIL, Montreal, Canada.

Zaharescu DG, Hooda PS, Soler AP, Fernandez J, Burghelea CI (2009). Trace metals and their source in the catchment of the high altitude Lake Respomuso, Central Pyrenees. Science of the Total Environment 407, 3546-3553.

Further information/links

Arsenic and other trace metals in the Central Pyrenees

The contamination with arsenic is a global problem affecting many areas including New England, Nevada and California in America, Taiwan, Argentina, India and Bangladesh (Nikolaidis et al., 2004). As is known for its harmful impact on human health which has been recognised globally, leading to setting up 10ppbAs as the maximum concentration in drinking water in the EU, America, Canada, Australia and numerous other countries. It can also be toxic to other biota or may bioaccumulate in them, resulting in its entrance into the food chain (Farias et al., 2003; Wang and Mulligan, 2006).

Arsenic is classified as a priority pollutant by the USEPA as it is carcinogenic metalloid (Pekey, 2006) and is also a List II substance under the EC Dangerous Substances Directive (Cave et al., 2005). The high altitude lakes are characterized by low ionic strength, clear waters, and oligotrophic conditions; are fed predominantly by atmospheric precipitation and are ice-covered during a large part of the year. These lakes are commonly on non-sedimentary basins, consequently their chemistry mainly reflects atmospheric deposition plus weathering of rocks in the catchment (Schnoor and Stumm, 1985). Other factors conditioning the chemical composition of water have less influence, because these lakes usually lie in poorly vegetated and uninhabited catchments. Nevertheless, such lakes may suffer also from geogenic metal contaminants but such examples in the literature are very scarce. Subias and Fernandez Nieto (1995) reported significantly high arsenic concentrations (13-26µg As/L) in some spring waters of the Tena valley (central Pyrenees), generally fountains situated at an altitude between 1300 and 3200 m. Lavilla et al. (2006) reported an increase in the total As in lake Respomuso sediments up to 339 mg kg-1 in recent years. This is a very high level of As and exceeds the ERL (8.27mg kg-1) and ERM (70mg kg-1) limits - the two sediment quality criteria.

The aim of the present study was to establish the source and contamination level for arsenic and other trace metals in the catchment of Respomuso lake and if this contamination is transmited to the Tena valley downstream.

Material and Methods

Two lakes of similar condition (reservoirs) and history at different altitudes were chosen: At 2121m, Lake Respomuso is a remote high-altitude lake that is post-glacial in origin and located in the central axis of the Spanish Pyrenees (Tena Valley, Sallent de Gallego). At 1080 m altitude Bubal lake is located on the course of Gallego river which link it to the upstream Respomuso lake. In the 1960s these lakes were dammed, along with several others, creating a series of reservoirs for hydroelectricity generation. The water from the catchment area is also used for drinking and the irrigation of crops in the Tena valley and below. We conducted a complete survey of trace metals in sediments (n=24), water (n=29) and snow (n=4) in the whole catchment area of Respomuso lake in the summer of 2006. The sampling locations were chosen to test all the surface water inputs from surrounding lakes and streams into Lake Respomuso and other key sites within the study area. The water and sediment samples were analysed for As and other elements (Cd, Ni, Co, Cr, Mn, Pb, Cu, Zn) using the ICP-MS and ICP-AES facilities at the School of Earth Sciences and Geography, Kingston University following standard procedure and QA/QC protocols.

Main Findings

The results showed high As, Cd, Ni concentrations in sediment with main sources in the South of the basin (up to 161 mg As kg-1 ) and high As concentration in waters from the East area (up to 14.22). The upper layer of snow patches showed particular high contamination with some metals: 19 µg As/L, 506 µg Mn/L and 156.33 µg Pb/L. This indicates that metal contamination at Respomuso might have two possible origins: geogenic from rocks weathering and aerial deposition, as seen seen in the snow samples.This is an important issue because the water is used for drinking and agriculture by the population of the Tena Valley and bellow.

The second research question was to study the connectivity through historical record between Respomuso lake and the water bodies downstream. We sampled sediment cores in lakes Respomuso and Bubal, a reservoir located downstream, in the Tena Valley. The results show a similar trend in metals concentrations through sediment layers in both lakes (with higher As concentrations in upper layers). This highlights a good chemical connectivity between the two water bodies but with the difference that in the downstream lake the As and other elements concentrations were much lower. This leads us to conclude that Respomuso reservoir stores a large fraction of metals inputs from its catchment. This study is especially useful for both scientific and public concern and offers a key to understanding geogenic contamination and its potential impact on the catchment biota which being compared with a number of climate, habitat and geochemical indicators.

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