HUMAN HISTORY AND ECOLOGICAL CHANGE AS RECORDED IN LAKE SEDIMENTS FROM THE SPANISH CENTRAL PYRENEES

Lake sediments can act as natural archives of regional environmental change due to both natural climate forcings and anthropogenic activities. The analysis of trace metal concentrations in lake sediments has been widely used to document the history of metallurgy, mining, and land use change. Here we present a 6,000-year long lake sediment record from Lake Montcortes in the Spanish Central Pyrenees that documents changes in the lake and its watershed caused by human activity. Previous work on sediment cores from Montcortes included sedimentological and mineralogical analysis and identified several periods of lake level fluctuation and erosional input related to both climatic change and human activity (Corella et al., 2011). We further complement this work by focusing on the concentrations of metals mobilized in an overnight weak acid extraction and measured via an inductively coupled plasma mass spectrometer (ICP-MS). We focus our interpretation on lead as it is mainly immobile once deposited in lake sediments, it is resistant to chemically reduced reactions, and has an affinity to bind to organic matter and clays. However, we supplement our interpretation with discussion and comparison of other metals such as iron, manganese, titanium, aluminum, and calcium. Our work shows measurable increases in concentrations of lead associated with early metallurgical activity as well as changes in erosional input from agricultural activities. Quantifying the magnitude of long-term metal pollution on Montcortes and the repercussions of anthropogenic activities in this region can ultimately provide an increasing understanding of the significance of pre-industrial metallurgy, human modification of landscapes, and the produced consequential environment conditions.