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Individual high-Alpine ice cores have been proven to contain a well-preserved history of past anthropogenic air pollution in western Europe. The question of how representative one ice core is with respect to the reconstruction of atmospheric composition in the source region has not been addressed so far. Here, we present the first study systematically comparing longer-term ice-core records (1750–2015 CE) of various anthropogenic compounds, such as major inorganic aerosol constituents (NH4+, NO3-, SO42-), black carbon (BC), and trace species (Cd, F−, Pb). Depending on the data availability for the different air pollutants, up to five ice cores from four high-Alpine sites located in the European Alps analysed by different laboratories were considered. Whereas absolute concentration levels can partly differ depending on the prevailing seasonal distribution of accumulated precipitation, all seven investigated anthropogenic compounds are in excellent agreement between the various sites for their respective, species-dependent longer-term concentration trends. This is related to common source regions of air pollution impacting the four sites less than 100 km away including western European countries surrounding the Alps. For individual compounds, the Alpine ice-core composites developed in this study allowed us to precisely time the onset of pollution caused by industrialization in western Europe. Extensive emissions from coal combustion and agriculture lead to an exceeding of pre-industrial (1750–1850) concentration levels already at the end of the 19th century for BC, Pb, exSO42- (non-dust, non-sea salt SO42-), and NH4+, respectively. However, Cd, F−, and NO3- concentrations started surpassing pre-industrial values only in the 20th century, predominantly due to pollution from zinc and aluminium smelters and traffic. The observed maxima of BC, Cd, F−, Pb, and exSO42- concentrations in the 20th century and a significant decline afterwards clearly reveal the efficiency of air pollution control measures such as the desulfurization of coal, the introduction of filters and scrubbers in power plants and metal smelters, and the ban of leaded gasoline improving the air quality in western Europe. In contrast, NO3- and NH4+ concentration records show levels in the beginning of the 21th century which are unprecedented in the context of the past 250 years, indicating that the introduced abatement measures to reduce these pollutants were insufficient to have a major effect at high altitudes in western Europe. Only four ice-core composite records (BC, F−, Pb, exSO42-) of the seven investigated pollutants correspond well with modelled trends, suggesting inaccuracies of the emission estimates or an incomplete representation of chemical reaction mechanisms in the models for the other pollutants. Our results demonstrate that individual ice-core records from different sites in the European Alps generally provide a spatially representative signal of anthropogenic air pollution trends in western European countries.

Ice cores are unique natural archives that provide important information about the past evolution of the Earth’s atmosphere. Whereas the inorganic atmospheric aerosol fraction is well characterized, the organic composition is less understood. The organic aerosol burden is consistently underestimated in the current state-of-the-art models, thus highlighting major gaps in our understanding of the pathways by which organic aerosols accumulate and evolve in the atmosphere. So far, organic aerosols in ice cores have been primarily reported as either bulk (e.g., water insoluble or dissolved organic carbon) or specific parameters (e.g., biomass burning tracers).To provide a more comprehensive characterization of the organic fraction, we applied a non-target screening approach optimised for determining oxidation products of volatile organic compounds to a firn core collected on the Corbassière glacier (Grand Combin, Swiss Alps), in 2020, covering the period 2008-2020. In comparison with a firn core drilled two years earlier (2018), we observe a drastic disturbance of seasonal trends for certain species, such as major ions at depths corresponding to the annual layers from 2008 to 2016, induced by meltwater percolation.As organic tracers are present in low concentrations in the firn core, we performed solid phase extraction. The organic tracers were analysed with high-resolution mass spectrometry based on Orbitrap technology coupled with liquid chromatography. This technique makes it possible to study a wide range of individual compounds at low concentration and to identify them with MS/MS fragmentation. We can attribute molecular formulas to detected compounds by comparing the MS/MS spectra with spectral libraries (e.g., mzCloud) or reference standards. With this approach we will present a unique record of molecular composition of organic aerosol in the Corbassière firn core.Furthermore, this firn core presents a unique opportunity to examine the effect of melting on the organic tracers. We found that specific burning tracers (e.g., vanillic acid, vanillin and syringaldehyde) are less affected than other biomass tracers (e.g., pinic acid) by meltwater percolation. In general, we observe a decrease in concentration of the organic tracers in the same firn core section where we also observe a decrease in major ion concentrations.

Atmospheric heavy metal pollution caused by metal smelting, mining, waste incineration and fossil fuel combustion presents a significant issue for human health and the environment. Anthropogenic emissions from the territory of the former Soviet Union (FSU) considerably influenced atmospheric concentrations of heavy metals. However, due to scarce monitoring data and fragmentary reporting, emissions quantities from this region are not well-known and it is even unclear if emissions decreased or increased after collapse of the Soviet Union. This is underlined by the fact that existing ice-core records and emission estimates based on national inventories for the FSU reveal an opposing trend for the most recent ~30 years. Here we present new records of post-Soviet Union anthropogenic heavy metal emissions (Bi, Cd, Cu, Pb, Sb, Zn) derived from three ice cores; from the Mongolian Altai (Tsambagarav ice core, period 1710-2009 AD) and the Siberian Altai (two Belukha ice cores, period 1680-2018 AD), covering a large regional footprint of emissions. The major source region of air pollution arriving at the Altai is primarily the territory of the FSU except for the eastern-most Siberian parts. Heavy metal concentrations at ultra-trace levels in the studied ice cores were analysed using inductively coupled plasma sector-field mass spectrometry (ICP-SF-MS). These records were complemented with new heavy metal emission estimates based on the available inventory data (1975-2015 AD) to derive a robust reconstruction of recent FSU heavy metal emissions. Consistent with the emission estimates, ice-core concentrations of Cd, Cu, Pb, Sb, Zn during the 2010s correspond to 20-40% of the maximum values in the 1970s and are comparable to their 1940s-1950s levels. A similar magnitude was also estimated for the decrease in Bi between 1975 and 2015, however, ice-core concentrations do not show a substantial downward trend.

The radiative effect of anthropogenic aerosols is one of the largest uncertainties in Earth's energy budget over the industrial period. This uncertainty is in part due to sparse observations of aerosol concentrations in the pre-satellite era. To address this lack of measurements, ice cores can be used, which contain the aerosol concentration record. To date, these observations have been under-utilized for comparison to aerosol concentrations found in state-of-the-art Earth system models (ESMs). Here we compare long term trends in concentrations of sulfate and black carbon (BC) between 15 ice cores and 11 ESMs over nine regions around the world during the period 1850–2000. We find that for sulfate concentration trends model results generally agree with ice core records, whereas for BC concentration the model trends differ from the records. Absolute concentrations of both investigated species are overestimated by the models, probably in part due to representation errors. However, we assume that biases in relative trends are not altered by these errors. Ice cores in the European Alps and Greenland record a maximum BC concentration before 1950, while most ESMs used in this study agree on a post-1950 maximum. We source this bias to an error in BC emission inventories in Europe. Emission perturbation experiments using NorESM2-LM support the observed finding that BC concentrations in Northern Greenland ice cores are recording European emissions. Errors in BC emission inventories have implications for all future and past studies where Coupled Model Intercomparison Project Phase 6 historical simulations are compared to observations relevant to aerosol forcing.

Earth's snow cover is very dynamic on diurnal timescales. The changes to the snow structure during this metamorphism have wide-ranging impacts on processes such as avalanche formation and on the capacity of surface snow to exchange trace gases with the atmosphere. Here, we investigate the influence of dry metamorphism, which involves fluxes of water vapour, on the chemical reactivity of bromide in the snow. To this end, the heterogeneous reactive loss of ozone in the dark at a concentration of 5×1012-6× 1012 molec. cm-3 is investigated in artificial, shock-frozen snow samples doped with 6.2μM sodium bromide and with varying metamorphism history. The oxidation of bromide in snow is one reaction initiating polar bromine releases and ozone depletion. We find that the heterogeneous reactivity of bromide is completely absent from the air-ice interface in snow after 12 d of temperature gradient metamorphism, and we suggest that the burial of non-volatile bromide salts occurs when the snow matrix is restructuring during metamorphism. Impacts on polar atmospheric chemistry are discussed. © Author(s) 2020., Atmospheric Chemistry and Physics, 20 (21), ISSN:1680-7375, ISSN:1680-7367

High-alpine glacier ice cores are useful natural archives and allow access to continuous pollution records back to the pre-industrial era. This is especially true for glacier ice cores drilled in the European Alps, which are located close to the anthropogenic emission sources. However, due to global warming glaciers are increasingly affected by melting, subsequently altering the information stored in the natural archive.Here we show the comparison between major ion records from shallow ice cores drilled on Grand Combin (4123 m a.s.l., Swiss Alps) in 2018 and 2020. Both shallow ice cores were dated applying annual layer counting using stable isotopes and concentrations of major ions (e.g., ammonium). Excellent agreement between both records was observed for the stable isotopes in the overlapping time period 2011-2018. However, in the core collected in 2020, effects of melting were detected for the major ion concentrations before 2016. As an extreme example: sulfate is significantly depleted in the years 2011-2016 in that core, losing 61% of the ion content in comparison with the core collected in 2018. Even for ammonium, which is the most preserved with only 16 % reduction, the seasonal cycle disappeared. The elution sequence matches the results of Avak et al. (2019).Meteorological data indicate that mean annual air temperatures of 2019 and 2020 were not significantly higher than in the previous years. Instead, we attribute the melt damage in the 2020 core to a two-week period in summer 2019 with temperatures continuously above 0°C. Our finding that such a disturbance through melting can occur in only two years emphasises the critical state of these glacier archives. Thus, preserving these archives is important and a time sensitive matter. REFERENCESAvak, S. E., Trachsel, J. C., Edebeli, J., Brütsch, S., Bartels‐Rausch, T., Schneebeli, M., Schwikowski, M. and Eichler, A.: Melt‐induced fractionation of major ions and trace elements in an Alpine snowpack, Journal of Geophysical Research F: Earth Surface, 124(7), 1647-1657, https://doi.org/10.1029/2019JF005026.

Wildfires have an important role in affecting the Earth’s radiative balance. Biomass burning aerosols can scatter or absorb the incoming solar radiation, alter the ice and snow albedo and act as cloud condensation nuclei. Overall, their net contribution to the Earth’s radiative forcing is negative, however this estimate has large uncertainties. To better assess the impact of wildfires on climate (and vice versa), it is crucial to reconstruct their past regional and temporal variability on decadal and centennial timescales. Ice cores are excellent archives to perform such palaeofire reconstructions. Previous studies have reconstructed the occurrence of wildfires in ice cores using both inorganic (ammonium, potassium and black carbon) and organic proxies (levoglucosan, vanillic acid and p-hydroxybenzoic acid). However, a more comprehensive view that involved a broader suite of wildfire proxies was missing. Here, we present a new SPE-UHPLC-HRMS method for the determination of five organic biomass burning tracers (syringic acid, vanillic acid, vanillin, syringaldehyde and p-hydroxybenzoic acid) and pinic acid, as biogenic emission proxy, in ice core samples. This method showed average recoveries of 76% (58-88% range), excellent inter-day reproducibility, no significant matrix effects and fast analysis time (13 min per sample). Comparing the published concentration ranges of the selected species from different ice core regions (i.e. Alps, Greenland, Kamchatka, China and Svalbard Archipelago) with the procedural detection limits of this new methodology, we conclude that four of the six targeted compounds can be successfully detected in real ice and snow samples. Only for vanillin and syringaldehyde, no ice-core measurements have been reported in the scientific literature so far. The method development also involved the evaluation of common laboratory practices such as the melting and refreezing of ice samples before the analysis. We found that the melting and refreezing of the samples resulted in a mass loss for the majority of the investigated compounds, which was more evident at lower concentrations. We hypothesize that the reason of this phenomenon is the adsorption of the compounds on the walls of the glass vials used for this study. In light of this, we propose alternative sample storage strategies that can also be extended for the analysis of other compounds.The method was successfully tested on nine ice core samples from the Colle Gnifetti (European Alps) and it will be applied on ice cores from the Alps and the Russian Altai, contributing to the better understanding of wildfire temporal evolution and their relations with climate.

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.

Understanding the impact of melting on the preservation of atmospheric compounds in high‐Alpine snow and glacier ice is crucial for future reconstruction of past atmospheric conditions. However, detailed studies investigating melt‐related changes of such proxy information are rare. Here we present a series of five snow pit profiles of 6 major ions and 34 trace elements at Weissfluhjoch, Switzerland, collected between January and June 2017. Atmospheric composition was preserved during the cold season, while melting toward the summer resulted in preferential loss of certain species from the snowpack or enrichment at the base of the snowpack. Increasing mobilization of major ions with meltwater (NH4+ < Cl− ~ Na+ < NO3− ~ Ca2+ ~ SO42−) can be related to their stronger enrichment at ice crystal surfaces during snow metamorphism. Results for trace elements show that less abundant elements such as Ce, Eu, La, Mo, Nd, Pb, Pr, Sb, Sc, Sm, U, and W were best preserved and may still serve as tracers to reconstruct past natural and anthropogenic atmospheric emissions from melt‐affected snow pit and ice core records. The obtained elution behavior matches the findings from another high‐Alpine site (upper Grenzgletscher) for major ions and the large majority of investigated trace elements. Both studies indicate that water solubility and location at the microscopic scale are likely to determine the relocation behavior with meltwater and also suggest that the observed species‐dependent preservation from melting snow and ice is representative for the Alpine region, reflecting Central European atmospheric aerosol composition., Journal of Geophysical Research: Earth Surface, 124 (7), ISSN:0148-0227, ISSN:2169-9003, ISSN:2169-9011

Herein we highlight recent mechanistic findings on the impact of solvent dynamics on catalysis displayed by squalene-hopene cyclases (SHCs). These fascinating biocatalysts that appeared early during the evolution of terpene biosynthetic machineries exploit a catalytic aspartic acid donating the anti-oriented proton to the terminal C C double bond of pre-folded isoprenoid substrates. We review how the unusual strength of this Bronsted acid can be used to harness a plethora of non-natural protonation-driven reactions in a plastic enzyme fold. Moreover, recent results underline how the reaction termination by deprotonation or water addition is governed by the spatial location of water in the active site. Site-directed mutagenesis of amino acids located in the hydrophobic binding pocket allows for the generation of novel catalytic function by active site reshaping with relatively small enzyme libraries. A deepened understanding of triterpene cyclase dynamics in concert with chemical expertise thus have a great potential to allow for the biocatalytic manufacturing of tailored building bricks that would expand the chemical repertoire currently found in nature.

Three shallow firn cores were retrieved in the austral summers of 2011/12 and 2013/14 on the ice rises Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), all part of Fimbul Ice Shelf (FIS) in western Dronning Maud Land (DML), Antarctica. The cores were dated back to 1958 (KC), 1995 (KM), and 1996 (BI) by annual layer counting using high-resolution oxygen isotope (δ18O) data, and by identifying volcanic horizons using non-sea-salt sulfate (nssSO42−) data. The water stable isotope records show that the atmospheric signature of the annual snow accumulation cycle is well preserved in the firn column, especially at KM and BI. We are able to determine the annual surface mass balance (SMB), as well as the mean SMB values between identified volcanic horizons. Average SMB at the KM and BI sites (0.68 and 0.70 mw. e. yr−1) was higher than at the KC site (0.24 mw. e. yr−1), and there was greater temporal variability as well. Trends in the SMB and δ18O records from the KC core over the period of 1958–2012 agree well with other previously investigated cores in the area, thus the KC site could be considered the most representative of the climate of the region. Cores from KM and BI appear to be more affected by local meteorological conditions and surface topography. Our results suggest that the ice rises are suitable sites for the retrieval of longer firn and ice cores, but that BI has the best preserved seasonal cycles of the three records and is thus the most optimal site for high-resolution studies of temporal variability of the climate signal. Deuterium excess data suggest a possible effect of seasonal moisture transport changes on the annual isotopic signal. In agreement with previous studies, large-scale atmospheric circulation patterns most likely provide the dominant influence on water stable isotope ratios preserved at the core sites.

The Amazon Basin is one of the major contributors to global biomass burning emissions. However, regional paleofire trends remain particularly unknown. Due to their proximity to the Amazon Basin, Andean ice cores are suitable to reconstruct paleofire trends in South America and improve our understanding of the complex linkages between fires, climate and humans. Here we present the first refractory black carbon (rBC) ice-core record from the Andes as a proxy for biomass burning emissions in the Amazon Basin, derived from an ice core drilled at 6300 m a.s.l. from the Illimani glacier in the Bolivian Andes and spanning the entire Holocene back to the last deglaciation 13 000 years ago. The Illimani rBC record displays a strong seasonality with low values during the wet season and high values during the dry season due to the combination of enhanced biomass burning emissions in the Amazon Basin and less precipitation at the Illimani site. Significant positive (negative) correlations were found with reanalyzed temperature (precipitation) data for regions in eastern Bolivia and western Brazil characterized by substantial fire activity. rBC long-term trends indirectly reflect regional climatic variations through changing biomass burning emissions as they show higher (lower) concentrations during warm–dry (cold–wet) periods, in line with climate variations such as the Younger Dryas, the 8.2 ka event, the Holocene Climatic Optimum, the Medieval Warm Period and the Little Ice Age. The highest rBC concentrations of the entire record occurred during the Holocene Climatic Optimum between 7000 and 3000 BCE, suggesting that this exceptionally warm and dry period caused high levels of biomass burning activity, unprecedented in the context of the past 13 000 years. Recent rBC levels, rising since 1730 CE in the context of increasing temperatures and deforestation, are similar to those of the Medieval Warm Period. No decrease in fire activity was observed in the 20th century, in contradiction to global biomass burning reconstructions based on charcoal data.

Accumulation and δ18O data from Alpine ice cores provide information on past temperature and precipitation. However, their correlation with seasonal or annual mean temperature and precipitation at nearby sites is often low. This is partly due to the irregular sampling of the atmosphere by the ice core (i.e. ice cores almost only record precipitation events and not dry periods) and the possible incongruity between annual layers and calendar years. Using daily meteorological data from a nearby station and reanalyses, we replicate the ice core from the Grenzgletscher (Switzerland, 4200 m a.s.l.) on a sample-by-sample basis by calculating precipitation-weighted temperature (PWT) over short intervals. Over the last 15 yr of the ice core record, accumulation and δ18O variations can be well reproduced on a sub-seasonal scale. This allows a wiggle-matching approach for defining quasi-annual layers, resulting in high correlations between measured quasi-annual δ18O and PWT. Further back in time, the agreement deteriorates. Nevertheless, we find significant correlations over the entire length of the record (1938–1993) of ice core δ18O with PWT, but not with annual mean temperature. This is due to the low correlations between PWT and annual mean temperature, a characteristic which in ERA-Interim reanalysis is also found for many other continental mid-to-high-latitude regions. The fact that meteorologically very different years can lead to similar combinations of PWT and accumulation poses limitations to the use of δ18O from Alpine ice cores for temperature reconstructions. Rather than for reconstructing annual mean temperature, δ18O from Alpine ice cores should be used to reconstruct PWT over quasi-annual periods. This variable is reproducible in reanalysis or climate model data and could thus be assimilated into conventional climate models.

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.

Cytochrome P450 monooxygenases can catalyse the stereoselective C-H activation of a very broad range of substrates. Prediction and control of enantioselectivity of this enzyme class is of great interest for the synthesis of high-value chiral molecules. Here we have used a combination of molecular dynamics simulations and experimental screening to study the enantioselectivity of a library of active-site mutants of chimeric P450cam-RhFRed towards the benzylic hydroxylation of structurally related regioisomers of ethylmethylbenzene. Small variations either in substrate structure or in enzyme active site architecture were shown to lead to dramatic changes in enantioselectivity; this was broadly in agreement with computational predictions. In addition to validating computational approaches, these studies have provided us with a deeper understanding of effects that might control stereoselectivity in these biooxidation reactions.

We present the records of the two nitrogen species nitrate (NO3-) and ammonium (NH4+) analysed in a new ice core from Lomonosovfonna, Svalbard, in the Eurasian Arctic covering the period 1222–2009. Changes in melt at the Lomonosovfonna glacier are assumed to have a negligible effect on the decadal variations of the investigated compounds. Accordingly, we use decadal records to investigate the major emission sources of NO3- and NH4+ precursors and find that during the twentieth century both records are influenced by anthropogenic pollution from Eurasia. In pre-industrial times NO3- is highly correlated with methane sulfonate (MSA), which we explain by a fertilising effect. We propose that enhanced atmospheric NO3- concentrations and the corresponding nitrogen input to the ocean trigger the growth of dimethyl-sulfide-(DMS)-producing phytoplankton. Increased DMS production results in elevated fluxes to the atmosphere where it is oxidised to MSA. Eurasia was presumably the main source area also of pre-industrial NO3-, but a more exact source apportionment could not be performed based on our data. This is different for NH4+, where biogenic ammonia (NH3) emissions from Siberian boreal forests were identified as the dominant source of pre-industrial NH4+.

Major ions were analysed in three firn cores from different ice rises located at Fimbul Ice Shelf (FIS): Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), a 100 m long core drilled near the FIS edge (S100), and five snow pits (M1, M2, G3, G4, and G5) sampled on the ice shelf. These sites are distributed over the entire FIS area so that they provide a variety of elevation and distance to the sea. Sea-salt species (mainly Na+ and Cl−) generally dominate the precipitation chemistry in the study region. Concentrations of these ions were found to decrease with latitude and distance from the sea. We associate a significant six-fold increase in sea-salts observed in the S100 core after the 1950s with a change in deposition regime. This increase in sea-salt concentrations is synchronous with a shift in non-sea-salt sulfate (nssSO42−) toward negative values, suggesting a possible contribution of fractionated aerosol to the sea-salt load in the S100 core most likely by dry deposition. In contrast, wet deposition of atmospheric sea-salts is dominant in the three ice rises cores, and no evidence of a significant contribution of fractionated sea-salt to these sites was found. In summary, these results suggest that the S100 core contains a more local sea-salt signal, dominated by processes during sea-ice formation in the neighbouring waters. In contrast, the ice rises cores register the larger-scale signal of atmospheric flow conditions and transport of sea-salt aerosols produced over open water rather than local changes in sea-ice, wind-blown snow accumulated over sea-ice, and frost flower formation. These findings are a contribution to the understanding of the mechanisms behind sea-salt aerosol production, transport and deposition at coastal Antarctic sites, and for the improvement of the current Antarctic sea-ice reconstructions based on sea-salt chemical proxies obtained from ice cores.

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.

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.

Glacier highstands since the Last Glacial Maximum are well documented for many regions, but little is known about glacier fluctuations and lowstands during the Holocene. This is because the traces of minimum extents are difficult to identify and at many places are still ice covered, limiting the access to sample material. Here we report a new approach to assess minimal glacier extent, using a 72-m long surface-to-bedrock ice core drilled on Khukh Nuru Uul, a glacier in the Tsambagarav mountain range of the Mongolian Altai (4130 m asl, 48°39.338′N, 90°50.826′E). The small ice cap has low ice temperatures and flat bedrock topography at the drill site. This indicates minimal lateral glacier flow and thereby preserved climate signals. The upper two-thirds of the ice core contain 200 years of climate information with annual resolution, whereas the lower third is subject to strong thinning of the annual layers with a basal ice age of approximately 6000 years before present (BP). We interpret the basal ice age as indicative of ice-free conditions in the Tsambagarav mountain range at 4100 m asl prior to 6000 years BP. This age marks the onset of the Neoglaciation and the end of the Holocene Climate Optimum. The ice-free conditions allow for adjusting the Equilibrium Line Altitude (ELA) and derive the glacier extent in the Mongolian Altai during the Holocene Climate Optimum. Based on the ELA-shift, we conclude that most of the glaciers are not remnants of the Last Glacial Maximum but were formed during the second part of the Holocene. The ice core derived accumulation reconstruction suggests important changes in the precipitation pattern over the last 6000 years. During formation of the glacier, more humid conditions than presently prevailed followed by a long dry period from 5000 years BP until 250 years ago. Present conditions are more humid than during the past millennia. This is consistent with precipitation evolution derived from lake sediment studies in the Altai.

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.

The extensive nuclear bomb testing of the fifties and sixties and the final tests in the seventies caused a strong 36Cl peak that has been observed in ice cores world-wide. The measured 36Cl deposition fluxes in eight ice cores (Dye3, Fiescherhorn, Grenzgletscher, Guliya, Huascarán, North GRIP, Inylchek (Tien Shan) and Berkner Island) were compared with an ECHAM5-HAM general circulation model simulation (1952–1972). We find a good agreement between the measured and the modeled 36Cl fluxes assuming that the bomb test produced global 36Cl input was ~80 kg. The model simulation indicates that the fallout of the bomb test produced 36Cl is largest in the subtropics and mid-latitudes due to the strong stratosphere-troposphere exchange. In Greenland the 36Cl bomb signal is quite large due to the relatively high precipitation rate. In Antarctica the 36Cl bomb peak is small but is visible even in the driest areas. The model suggests that the large bomb tests in the Northern Hemisphere are visible around the globe but the later (end of sixties and early seventies) smaller tests in the Southern Hemisphere are much less visible in the Northern Hemisphere. The question of how rapidly and to what extent the bomb produced 36Cl is mixed between the hemispheres depends on the season of the bomb test. The model results give an estimate of the amplitude of the bomb peak around the globe.

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.

The spatial representation of accumulation measurements is a major limitation for current glacier mass balance monitoring approaches. Here, we present a method for estimating annual accumulation rates on a temperate Alpine glacier based on the interpretation of internal reflection horizons (IRHs) in helicopter-borne ground-penetrating radar (GPR) data. For each individual GPR measurement, the signal travel time is combined with a simple model for firn densification and refreezing of meltwater. The model is calibrated at locations where GPR repeat measurements are available in two subsequent years and the densification can be tracked over time. Two 10.5 m long firn cores provide a reference for the density and chronology of firn layers. Thereby, IRHs correspond to density maxima, but not exclusively to former summer glacier surfaces. Along GPR profile sections from across the accumulation area we obtain the water equivalent (w.e.) of several annual firn layers. Because deeper IRHs could be tracked over shorter distances, the total length of analysed profile sections varies from 7.3 km for the uppermost accumulation layer (2011) to 0.1 km for the deepest (i.e. oldest) layer (2006). According to model results, refreezing accounts for 10% of the density increase over time and depth, and for 2% of the water equivalent. The strongest limitation to our method is the dependence on layer chronology assumptions. We show that GPR can be used not only to complement existing mass balance monitoring programmes on temperate glaciers but also to retrospectively extend newly initiated time series., The Cryosphere, 9 (3), ISSN:1994-0416, ISSN:1994-0424

The spatial representation of accumulation measurements is a major limitation for current glacier mass balance monitoring approaches. Here, we present a new method for estimating annual accumulation rates on a temperate alpine glacier based on the interpretation of internal reflection horizons (IRH) in helicopter-borne ground-penetrating radar (GPR) data. For each individual GPR measurement, the signal traveltime is combined with a simple model for firn densification and refreezing of meltwater. The model is calibrated at locations where GPR profiles intersect in two subsequent years and the densification can be tracked over time. Two 10.5 m long firn cores provide a reference for the density and chronology of firn layers. Thereby, IRH correspond to density maxima, but not exclusively to former summer glacier surfaces. From GPR profiles across the accumulation area, we obtain spatial distributions of water equivalent for at least four annual firn layers, reaching a mean density of 0.74 g cm−3. Refreezing accounts for 9% of the density increase over time and depth. The strongest limitation to our method is the dependence on layer chronology assumptions. The uncertainties inherent to the modelling approach itself are in the same order of conventional point measurements in snow pits. We show that GPR can be used to complement existing mass balance monitoring programs on temperate alpine glaciers, but also to retrospectively extend newly initiated time series.

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.

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 210Pb, (ii) seasonally varying signals such as the concentrations of NH4+ and the isotopic ratio δ18O, 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

In this study, the development of a new sensitive method for the analysis of alpha-dicarbonyls glyoxal (G) and methylglyoxal (MG) in environmental ice and snow is presented. Stir bar sorptive extraction with in situ derivatization and liquid desorption (SBSE-LD) was used for sample extraction, enrichment, and derivatization. Measurements were carried out using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). As part of the method development, SBSE-LD parameters such as extraction time, derivatization reagent, desorption time and solvent, and the effect of NaCl addition on the SBSE efficiency as well as measurement parameters of HPLC-ESI-MS/MS were evaluated. Calibration was performed in the range of 1–60 ng/mL using spiked ultrapure water samples, thus incorporating the complete SBSE and derivatization process. 4-Fluorobenzaldehyde was applied as internal standard. Inter-batch precision was

Different biological proxies such as pollen, cysts, and diatoms were identified and quantified in the upper part of a Belukha ice core from the Russian Altai. The ice core from the Belukha glacier collected in 2001 (4062 m a.s.l., 49°48' N, 86°34' E) was analyzed with annual resolution in the period 1964–2000. Daily data of the frequency of synoptic patterns observed in the Northern Hemisphere along with daily data of precipitation have been used to identify the predominant atmospheric circulations (elementary circulating mechanisms, or ECMs) generating the entry of biological proxies on the glacier surface. It was shown that the high-resolution records of diatoms, cysts, spores, and plant pollen in the Belukha ice core are the biological proxies for the changes in the structure of precipitation in the Altai region since these records can reflect changes in the contribution of different atmospheric circulation to annual or seasonal precipitation. The joint consideration of the transport ability of the biological species and the data of precipitation allowed us to determine the main modern sources of biological proxies deposited at the Belukha glacier. The main sources of diatoms in the Belukha ice core are water bodies of the Aral, Caspian, and northern Kazakhstan basins; coniferous tree pollen originated from the taiga forest of the boreal zone of western Siberia; pollen of deciduous trees and herbs from steppe and forest-steppe vegetation in the northern Altai and eastern Kazakhstan; and cysts and spores of plants were transported from local water bodies and forests. The identified source regions of the biological species are supported by back trajectory analyses and are in good agreement with emission source regions of the trace elements in the ice core.

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.

[1] Emissions from forests represent an important source of gaseous precursors of aerosols that can significantly alter the regional radiation balance. Long-term records of biogenic emissions are available for Northern America and the Amazon Basin, whereas the historical development of emissions from Siberian forests, comprising about 20% of the world's forested area, is unknown so far. Here we investigate ice core ammonium and formate records for the last 750 years, representing biogenic emissions from boreal Siberian forests in the pre-industrial era. Biogenic emissions were found to be closely related to changes in temperature following variations in solar activity. In addition, anthropogenic emissions have caused a strong increase of the ammonium concentrations and a drop of the formate concentrations in the last 60 years.

[1] The role of the sun on Earth’s climate variability is still much debated. Here we present an ice core oxygen isotope record from the continental Siberian Altai, serving as a high-resolution temperature proxy for the last 750 years. The strong correlation between reconstructed temperature and solar activity suggests solar forcing as a main driver for temperature variations during the period 1250–1850 in this region. The precisely dated record allowed for the identification of a 10–30 year lag between solar forcing and temperature response, underlining the importance of indirect sun-climate mechanisms involving ocean-induced changes in atmospheric circulation. Solar contribution to temperature change became less important during industrial period 1850–2000 in the Altai region. Citation: Eichler, A., S. Olivier, K. Henderson, A. Laube, J. Beer, T. Papina, H. W.

The Alps represent the largest barrier to meridional air flow in Europe, strongly influencing the weather and hence the distribution of atmospheric trace components. Here for the first time, chemical records from two ice cores retrieved from glaciers located in the northern and southern Swiss Alps were compared in conjunction with an analysis of "weather type", in order to assess geographical and seasonal trends in the deposition of trace species and to identify source regions and transport patterns. Using a correlation analysis, investigated trace species (NH4+, NO3−, SO42−, Ca2+, Mg2+, Na+, K+, and Cl− were grouped into classes of different origin (anthropogenic, sea salt, or Saharan dust). Over the last 60 years, precipitation chemistry at both sites was dominated by NH4+, NO4−, and SO42−, all of anthropogenic origin and deposited mainly in summer by way of convective precipitation. The similarity of the SO42− profiles with historical records of SO4 emissions from France and Italy indicated these two countries as key source areas for the anthropogenic species. In contrast, sea salt and Saharan dust showed major differences in transport pattern and deposition across the Alps. Currently, the sea-salt constituents Na+, K+, and Cl− are transported to the northern site during advective westerly-wind situations, independent of Saharan dust events. At the southern site, sea salt and Saharan dust are deposited simultaneously, indicating a coupled transport active mainly in summer during south-westerly wind situations.

This paper investigates the work practices of a team engaged in software R&D. Thus it is located at the interface of the project management model and its specifications in innovation management and software development.

In this chapter we report on the RepTool,1 a computer based tool for the collection, analysis, and presentation of data about “workscapes.” Users of the tool collect relevant information about workplaces and workpractices in a central data structure on which the tool provides different views. Physical, social, and cognitive spaces in users’ or customers’ environments can be represented and analyzed. The RepTool supports systematic data collection and collaborative data analysis that can help people at all levels of an organization build a shared view of the formal and informal work processes they participate in. A tool for collaborative knowledge management, it nurtures intra- and inter-team conversations that can lead to an empirically grounded, shared view of current realities and potentially necessary changes.

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) d13C and d18O 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 d13C data contain a strong summer temperature signal while d18O 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 d13C 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 d18O trend agrees with the precipitation reconstruction from the Teletskoe lake sediment indicating more humid conditions during the 20th century. Therefore these two proxies could be combined for the precipitation reconstruction.