Calibrations of paleoenvironmental records in (sub)recent tufa
Palaeoenvironmental interpretations based on geological and geochemical proxies are fundamental to our understanding of past and present climate and environmental changes. Most proxy definitions depend upon analogy with modern-day relationships, where high-resolution (monthly to decadal) laminated carbonaceous proxies, such as tufas or speleothems, have high potential to reconstruct not only global and regional climate sensitivity, but also the response of local hydrology to environmental and climate change. Each proxy type, however, is subject to a unique combination of uncertainties that obscure the climate signals of interest. Some of them relate to the multiple influences on many proxy recorders (e.g. δ18O and δ13C values, Me/Ca ratios of carbonate). Other sources of variability come from measurement precision (e.g. detection limits of trace metal analysis) and the variance among samples assumed to represent the same environment. Lumped together, these sources of uncertainty represent noise relative to a signal whose variation in time is often small compared to the noise.
High-resolution palaeoenvironmental data play a critical role in the detection and attribution of regional climate change associated with anthropogenic influences, including current global warming. These applications typically involve the use of high-resolution climate data in multi-proxy syntheses; they demand a quantitative, transparent and thorough representation of uncertainties associated with high-resolution proxy data. Typical high resolution records are (sub)recent massive and laminated tufas, which are quite common on the Dinaric carbonate platform, but still poorly understood. Metals (including selected radionuclides) introduced by human activities into the river environment accumulate within sediments and are, therefore, useful indicators of anthropogenic inputs. A fundamental characteristic of ecotoxic metals is their lack of biodegradability. Once introduced into the aquatic environment, trace metals and researched radionuclides are redistributed throughout the water column, deposited or accumulated in sediments and potentially consumed by biota.