Anja Eichler

Glaciochemical dating of an ice core from upper Grenzgletscher (4200 m a.s.l.)

One crucial condition for the interpretation of ice-core records is the establishment of an accurate time-scale. This task is especially difficult for glacier sites in a complex topography such as the Alps, due to the often irregular deposition of fresh precipitation. In this work, dating techniques were applied to an Alpine ice core from upper Grenzgletscher, Monte Rosa massif (4200 m a.s.l.), representing about two-thirds of the total glacier thickness. They are based on (i) the radioactive decay of the isotope 210 Pb, (ii) seasonally varying signals such as the concentrations of NH 4 + and the isotopic ratio δ 18 O, and (iii) stratigraphic markers from Saharan dust falls, atmospheric nuclear weapon tests and the reactor accident in Chernobyl. From the combined application of these dating methods, a time period of 1937-94 covered by the ice core was derived. Dating uncertainty is <1 year for the period 1970-94 and ± 2 years for the period 1937-69. The observed thinning of the annual layers as a function of depth could be well described by a simple kinematic glacier flow model.

Three Centuries of Eastern European and Altai Lead Emissions Recorded in a Belukha Ice Core

Human activities have significantly altered atmospheric Pb concentrations and thus, its geochemical cycle, for thousands of years. Whereas historical Pb emissions from Western Europe, North America, and Asia are well documented, there is no equivalent data for Eastern Europe. Here, we present ice-core Pb concentrations for the period 1680-1995 from Belukha glacier in the Siberian Altai, assumed to be representative of emissions in Eastern Europe and the Altai. Pb concentrations and (207)Pb/(206)Pb ratios were strongly enhanced during the period 1935-1995 due to the use of Pb additives in Russian gasoline mined in the Rudny Altai. Comparable to Western Europe and North America, Eastern European Pb emissions peaked in the 1970s. However, the subsequent downward trend in Eastern Europe was mainly caused by the economic crisis in the U.S.S.R. and not by a phase-out of leaded gasoline. Pb concentrations in the period 1680-1935, preceding the era of intensified industrialization in Russia, reflect the history of local emissions from Rudny Altai mining and related metallurgical processing primarily for the production of Russian coins. During this time, Altai ore Pb contributed about 40% of the regional atmospheric Pb.

A multi-proxy approach for revealing recent climatic changes in the Russian Altai

For the first time we present a multi-proxy data set for the Russian Altai, consisting of Siberian larch tree-ring width (TRW), latewood density (MXD), δ13C and δ18O in cellulose chronologies obtained for the period 1779–2007 and cell wall thickness (CWT) for 1900–2008. All of these parameters agree well between each other in the high-frequency variability, while the low-frequency climate information shows systematic differences. The correlation analysis with temperature and precipitation data from the closest weather station and gridded data revealed that annual TRW, MXD, CWT, and δ13C data contain a strong summer temperature signal, while δ18O in cellulose represents a mixed summer and winter temperature and precipitation signal. The temperature and precipitation reconstructions from the Belukha ice core and Teletskoe lake sediments were used to investigate the correspondence of different independent proxies. Low frequency patterns in TRW and δ13C chronologies are consistent with temperature reconstructions from nearby Belukha ice core and Teletskoe lake sediments showing a pronounced warming trend in the last century. Their combination could be used for the regional temperature reconstruction. The long-term δ18O trend agrees with the precipitation reconstruction from the Teletskoe lake sediment indicating more humid conditions during the twentieth century. Therefore, these two proxies could be combined for the precipitation reconstruction.

Ice-Core Based Assessment of Historical Anthropogenic Heavy Metal (Cd, Cu, Sb, Zn) Emissions in the Soviet Union

The development of strategies and policies aiming at the reduction of environmental exposure to air pollution requires the assessment of historical emissions. Although anthropogenic emissions from the extended territory of the Soviet Union (SU) considerably influenced concentrations of heavy metals in the Northern Hemisphere, Pb is the only metal with long-term historical emission estimates for this region available, whereas for selected other metals only single values exist. Here we present the first study assessing long-term Cd, Cu, Sb, and Zn emissions in the SU during the period 1935-1991 based on ice-core concentration records from Belukha glacier in the Siberian Altai and emission data from 12 regions in the SU for the year 1980. We show that Zn primarily emitted from the Zn production in Ust-Kamenogorsk (East Kazakhstan) dominated the SU heavy metal emission. Cd, Sb, Zn (Cu) emissions increased between 1935 and the 1970s (1980s) due to expanded non-ferrous metal production. Emissions of the four metals in the beginning of the 1990s were as low as in the 1950s, which we attribute to the economic downturn in industry, changes in technology for an increasing metal recovery from ores, the replacement of coal and oil by gas, and air pollution control.

An Alpine ice‐core record of anthropogenic HF and HCl emissions

Ice-core records of an Alpine glacier from the southern Swiss Alps were used to reconstruct sources of inorganic F and Cl− in precipitation. Our results suggest that sea salt transported together with mineral dust mainly from the Saharan area is the predominant source of Cl− in the southern Alps. However, on the average 16% of the Cl− and most of the F deposition in the period 1937–94 could be related to HCl and HF emissions from anthropogenic sources. The record of non-sea-salt Cl− was found to represent the historical development of HCl emissions mainly from waste incineration in the Swiss Plateau, whereas the F deposition record reflects HF emissions from the aluminum industry in the Swiss Rhone valley. Thus, our data indicate a strong impact of emissions of short lived atmospheric species such as HCl and HF on local and regional precipitation chemistry.

Pb pollution from leaded gasoline in South America in the context of a 2000-year metallurgical history.

Ice core records show that anthropogenic Pb pollution levels from road traffic in South America exceed those of any historical metallurgy. Exploitation of the extensive polymetallic deposits of the Andean Altiplano in South America since precolonial times has caused substantial emissions of neurotoxic lead (Pb) into the atmosphere; however, its historical significance compared to recent Pb pollution from leaded gasoline is not yet resolved. We present a comprehensive Pb emission history for the last two millennia for South America, based on a continuous, high-resolution, ice core record from Illimani glacier. Illimani is the highest mountain of the eastern Bolivian Andes and is located at the northeastern margin of the Andean Altiplano. The ice core Pb deposition history revealed enhanced Pb enrichment factors (EFs) due to metallurgical processing for silver production during periods of the Tiwanaku/Wari culture (AD 450–950), the Inca empires (AD 1450–1532), colonial times (AD 1532–1900), and tin production at the beginning of the 20th century. After the 1960s, Pb EFs increased by a factor of 3 compared to the emission level from metal production, which we attribute to gasoline-related Pb emissions. Our results show that anthropogenic Pb pollution levels from road traffic in South America exceed those of any historical metallurgy in the last two millennia, even in regions with exceptional high local metallurgical activity.

A 320-year ice-core record of atmospheric Hg pollution in the Altai, Central Asia

Anthropogenic emissions of the toxic heavy metal mercury (Hg) have substantially increased atmospheric Hg levels during the 20th century compared to preindustrial times. However, on a regional scale, atmospheric Hg concentration or deposition trends vary to such an extent during the industrial period that the consequences of recent Asian emissions on atmospheric Hg levels are still unclear. Here we present a 320 year Hg deposition history for Central Asia, based on a continuous high-resolution ice-core Hg record from the Belukha glacier in the Siberian Altai, covering the time period 1680-2001. Hg concentrations and deposition fluxes start rising above background levels at the beginning of the 19th century due to emissions from gold/silver mining and Hg production. A steep increase occurs after the 1940s culminating during the 1970s, at the same time as the maximum Hg use in consumer products in Europe and North America. After a distinct decrease in the 1980s, Hg levels in the 1990s and beginning of the 2000s return to their maximum values, which we attribute to increased Hg emissions from Asia. Thus, rising Hg emissions from coal combustion and artisanal and small-scale gold mining (ASGM) in Asian countries determine recent atmospheric Hg levels in Central Asia, counteracting emission reductions due to control measures in Europe and North America.

Ice-core evidence of earliest extensive copper metallurgy in the Andes 2700 years ago

The importance of metallurgy for social and economic development is indisputable. Although copper (Cu) was essential for the wealth of pre- and post-colonial societies in the Andes, the onset of extensive Cu metallurgy in South America is still debated. Comprehensive archaeological findings point to first sophisticated Cu metallurgy during the Moche culture ~200–800 AD, whereas peat-bog records from southern South America suggest earliest pollution potentially from Cu smelting as far back as ~2000 BC. Here we present a 6500-years Cu emission history for the Andean Altiplano, based on ice-core records from Illimani glacier in Bolivia, providing the first complete history of large-scale Cu smelting activities in South America. We find earliest anthropogenic Cu pollution during the Early Horizon period ~700–50 BC, and attribute the onset of intensified Cu smelting in South America to the activities of the central Andean Chiripa and Chavin cultures ~2700 years ago. This study provides for the first time substantial evidence for extensive Cu metallurgy already during these early cultures.

Alpine Glaciers as Archives of Atmospheric Deposition

Alpine glaciers are natural archives of past precipitation. At high elevations where melting is negligible and precipitation occurs as snow throughout the year the manifold information contained in the annual snow layers is well preserved. This information is accessed by ice core drilling and analyses. The stable isotope composition of water and the chemical impurities in the ice allow reconstructing past climate conditions and air pollution. The time period covered by suitable glaciers in the Alps depends on accumulation rate and glacier thickness and varies from a few hundred to more than 10,000 years. Concentration records of various trace species demonstrate the impact of anthropogenic emissions on the impurity content of snow. They show a generally consistent picture of a vastly altered atmospheric composition due to anthropogenic activities. Compared to rain samples from the vicinity of Zurich, concentrations of chemical impurities in Alpine ice are lower by a factor of 3–4, reflecting the different vertical and horizontal distance to the emission sources.