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Atmospheric deposition of large-scale lead pollution has occurred for at least 3000 years in Europe. Metal production and smelting were the main sources until the twentieth century when emissions from vehicles using alkyl-leaded petrol became dominant. Analyses of lake-sediment and peat deposits in Sweden and other regions in Europe, as well as ice cores from Greenland, suggest synchronous temporal changes in past pollution deposition. Characteristic features in the atmospheric pollution fallout were caused by: the peak in lead pro duction during the Roman period; the marked Mediaeval increase in mining and metal production; the rapidly increasing use of cars and leaded gasoline after the second world war along with increased industrial emissions until around 1970, which was followed by a major improvement due to environmental legislation. For northern Europe at least, these characteristic changes can be used to determine, with reasonable accuracy, at which levels ad 0, ad 1000–1200 and ad 1970 are situated in lake-sediment deposits. To identify these levels, stable lead isotope analyses (206Pb/207Pb ratios) have proven to be very useful besides concentration determinations. Particularly useful are the isotope analyses in areas, such as Sweden, where the differences in 206Pb/207Pb ratios are large between the natural catchment lead and the pollution lead.

We used a collection of ten freeze cores of annually laminated (varved) lake sediment from Nylandssjö n in northern Sweden collected from 1979 to 2007 to follow the long-term loss of carbon (C) and nitrogen (N) due to processes that occur in the lake bottom as sediment ages. We compared specific years in the different cores. For example, the loss of C from the surface varve of the 1979 core (sediment deposited during 1978) was followed in the cores from 1980, 1985, 1989, and so on until 2006. The C concentration of the sediment decreased by 20% and N decreased by 30% within the first five years after deposition, and after 27 yr in the sediment, there was a 23% loss of C and 35% loss of N. Because the relative loss of C with time was smaller than loss of N, the C : N ratio increased with increasing age of the sediment; the surface varves start with a ratio of ,10, which then increases to ,12.

Over recent decades, palaeolimnological records from remote sites have provided convincing evidence for the onset and development of several facets of global environmental change. Remote lakes, defined here as those occurring in high latitude or high altitude regions, have the advantage of not being overprinted by local anthropogenic processes. As such, many of these sites record broad-scale environmental changes, frequently driven by regime shifts in the Earth system. Here, we review a selection of studies from North America and Europe and discuss their broader implications. The history of investigation has evolved synchronously with the scope and awareness of environmental problems. An initial focus on acid deposition switched to metal and other types of pollutants, then climate change and eventually to atmospheric deposition-fertilising effects. However, none of these topics is independent of the other, and all of them affect ecosystem function and biodiversity in profound ways. Currently, remote lake palaeolimnology is developing unique datasets for each region investigated that benchmark current trends with A celebration of Prof. Rick Battarbee's contributions to palaeolimnology, edited by Holmes et al.This paper has been written as a contribution to celebrating Rick Battarbee's influence on palaeolimnology. Some of us have benefitted from his leadership (and friendship) in transnational European projects during the last decade (e.g., ALPE, ALPE2, MOLAR, CHILL-10000, EMERGE, EUROLIMPACS), which together with some other initiatives spawned pan-European remote lake research. Others have respected Rick as a teacher, colleague and a friend. To some extent, this review follows the chronological order of topics addressed in these projects, which also respond to the growing social awareness about each issue. Rick also facilitated bridges between North American and European schools, and beyond. We expect his attitude towards collaboration will pervade and persist through the palaeolimnological community for years to come, and global change will certainly provide stimulating and challenging questions with which to do so.

There is great concern for contamination of sensitive ecosystems in high latitudes by long-range transport of heavy metals and other pollutants derived from industrial areas in lower latitudes. Atmospheric pollution of heavy metals has a very long history, and since metals accumulate in the environment, understanding of present-day pollution conditions requires knowledge of past atmospheric deposition. We use analyses of lead concentrations and stable lead isotopes ( 206 Pb/ 207 Pb ratios) of annually laminated sediments from four lakes in northern Sweden (∼65°N) to provide a decadal record of atmospheric lead pollution for the last 3000 years. There is a clear signal in the sediments of airborne pollution from Greek and Roman cultures 2000 years ago, followed by a period of "clean" conditions 400-900 A.D. From 900 A.D. there was a conspicuous, permanent increase in atmospheric lead pollution fallout. The sediments reveal peaks in atmospheric lead pollution at 1200 and 1530 A.D. comparable to present-day levels. These peaks match the history of metal production in Europe. This study indicates that the contemporary atmospheric pollution climate in northern Europe was established in Medieval time, rather than in the Industrial period. Atmospheric lead pollution deposition did not, when seen in a historical perspective, increase as much as usually assumed with the Industrial Revolution (1800 A.D.).

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spectroscopy at an alpine lake (Sjuodjijaure) in northern SwedenHolocene climatic change reconstructed from diatoms, chironomids, pollen and near-infrared http://hol.sagepub.com/cgi/content/abstract/11/5/551The online version of this article can be found at: Abstract:The results of a multiproxy study reconstructing the climate history of the last 9300 years in northern Sweden are presented. It is based on diatom, chironomid and pollen analyses, as well as near-infrared spectroscopy (NIRS), of a radiocarbon dated sediment core from Sjuodjijaure (67°22ЈN, 18°04ЈE), situated 100 m above tree-line in the Scandes mountains. Mean July air temperature was reconstructed using transfer functions established for the region. The biological proxies show significant changes in composition during the Holocene and the inferred temperatures all follow the same general trend. For the period between about 9300 to 7300 cal. BP the reconstructions should be interpreted with caution due to the lack of convincing modern analogues in the training set. However the reconstruction suggest that July temperature was on average about the same as today, with several rapid short-term cold and warm periods. Cold periods were dated to about 8500, 8200 and 7600 cal. years BP and a warm period to about 7700 cal. BP. About 7300 cal. BP, a major shift to a warmer climate occurred. Pine migrated into the area, which was previously covered with birch forest. From the mid-Holocene until today the sediment record suggests a descending tree-limit and a gradual lowering of July temperature.