Lysevatten, a lake in southwest Sweden, has experienced both acidification and recent changes in the amount of lake-water organic carbon (TOC), both causing concern across Europe and North America. A ...range of paleolimnological tools – diatom-inferred pH, inferred lake-water TOC from visible-near-infrared spectroscopy (VNIRS), multi-element geochemistry and pollen analysis, combined with geochemical modeling were used to reconstruct the lake's chemistry and surroundings back to the most recent deglaciation 12 500 years ago. The results reveal that the recent anthropogenic impacts are similar in magnitude to the long-term variation driven by natural catchment changes and early agricultural land use occurring over centuries and millennia. The combined reconstruction of both lake-water TOC and lithogenic element delivery can explain the major changes in lake-water pH and modeled acid neutralizing capacity during the past 12 500 years. The results raise important questions regarding what precisely comprises "reference" conditions (i.e., free from human impacts) as defined in the European Water Framework Directive.
We subjected a unique set of high-quality paleoecological data to statistical modeling to examine if the biological richness and evenness of freshwater diatom communities in the Falun area, a ...historical copper (Cu) mining region in central Sweden, was negatively influenced by 1000 years of metal exposure. Contrary to ecotoxicological predictions, we found no negative relation between biodiversity and the sedimentary concentrations of eight metals. Strikingly, our analysis listed metals (Co, Fe, Cu, Zn, Cd, Pb) or the fractional land cover of cultivated crops, meadow, and herbs indicating land disturbance as potentially promoting biodiversity. However, correlation between metal- and land-cover trends prevented concluding which of these two covariate types positively affected biodiversity. Because historical aqueous metal concentrationsinferred from solid-water partitioningapproached experimental toxicity thresholds for freshwater algae, positive effects of metal mining on biodiversity are unlikely. Instead, the positive relationship between biodiversity and historical land-cover change can be explained by the increasing proportion of opportunistic species when anthropogenic disturbance intensifies. Our analysis illustrates that focusing on the direct toxic effects of metals alone may yield inaccurate environmental assessments on time scales relevant for biodiversity conservation.
Analysis of stable lead isotopes and lead concentrations in lake-sediment deposits, not least in varved (annually-laminated) sediments, is a useful method to study lead pollution history. This paper ...presents details from a study of 31 lakes in Sweden. Using a strong acid digestion of sediment samples and ICP-MS analyses, we have found that Swedish lake sediments have a high natural (pre-pollution)
206Pb/
207Pb ratio (mean 1.52±0.18, range 1.28–2.01,
n=31 lakes). In contrast, atmospheric lead pollution derived from metal smelting processes, coal burning and from alkyl-lead added to petrol has a lower ratio (<1.2). Consequently, when pollution lead deposition began approximately 3500 years ago, the lead isotope ratio of the sediments started to decline, and in modern sediments it is typically <1.2. Using the isotope and concentration values and a mixing model, the relative contribution of pollution and natural lead in sediment samples can be calculated. The pollution lead records of the Swedish lake sediments show a consistent picture of the atmospheric lead pollution history. Some noticeable features are the Roman peak (approx. 0
ad), the large and permanent Medieval increase (approx. 1000
ad), peaks at approximately 1200 and 1530
ad, the rapid increase after World War II, the peak in the 1970s, and the large modern decline.
The aim of this study was to determine the spatial variability for total‐ and methylmercury in surface sediments (0–2 cm) across a single whole‐lake basin, and to relate this variability to the ...sediment's geochemical composition. 83 surface sediment samples from Stor‐Strömsjön – a lake with multiple sub‐basins located in northern Sweden – were analyzed for geochemical composition as well as total‐mercury (total‐Hg) and methylmercury (methyl‐Hg; 35 samples) concentrations. Our results indicate that variations in fine‐grained mineral matter (36%) and organic matter (34%) explain an equal amount of the total‐Hg variation, but that their relative importance varies between different parts of the lake. Total‐Hg concentrations were similar in locations controlled by organic matter or fine‐grained mineral matter (average 109 ng g−1); however, total‐Hg inventories (mass per unit area) were significantly higher in the latter (35 and 53 μg m−2, respectively). Methyl‐Hg concentrations are largely (55% of variance) controlled by water depth and sulfur concentration, which supports the importance of within lake methylation reported from other studies. Both for concentrations and inventories the spatial distribution for methyl‐Hg in surface sediments is patchy, and interestingly the highest methyl‐Hg inventory (1.4 μg m−2) was found in a shallow location with coarse‐grained minerogenic sediment (very low organic matter). A large spatial variability, even within a single lake, is something that needs to be recognized, e.g., when studying processes affecting mercury cycling, mercury loadings and when using lake sediments to reconstruct historic mercury deposition.
Key Points
Hg and especially methyl‐Hg is highly spatially variable also in a single lake
Total‐Hg is controlled by either fine‐grained mineral matter or organic matter
Methyl‐Hg seems to mostly originate from in‐lake methylation
► The use of lead isotopes in multiproxy approach to trace pottery provenance is tested. ► Pottery fragments and potential clay sources from Cyprus are analyzed. ► Various origins are proposed for ...the pottery fragments. ► A link is established between the pottery fragments and some clay sources. ► Clay processing prior to pottery making is attested.
Lead isotope analyses were carried out on fragments of White Slip II ware, a Late Bronze Age Cypriote pottery ware, and on raw materials possibly used for their production. Sherds originate from three Late Bronze Age sites (Hala Sultan Tekke and Sanidha in Cyprus and Minet el-Beida in Syria) and clays come from the surroundings of Sanidha, a production site for White Slip ware. X-ray fluorescence (XRF) and a Principal Component Analysis (PCA) are combined with Pb isotope analyses to further investigate the effectiveness of the latter method within a multiproxy approach for pottery provenance study. The pottery sherds from the three sites are compared between themselves and with potential raw material. Additional X-ray diffraction (XRD) and analyses using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray detection (EDX) facility were performed on selected sherds and clays. This work confirms that the clay source used for pottery production in Sanidha derives from local weathered gabbro. It also shows that different origins can be proposed for White Slip II ware sherds from Hala Sultan Tekke and Minet el-Beida and that clays were prepared prior to White Slip II ware production. It finally confirms the effectiveness of Pb isotopes in tracing pottery provenance not only by comparing sherd assemblages but also by comparing sherds to potential raw materials.
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.
This paper presents a large palaeolimnological study of the pre-industrial and industrial history of atmospheric lead pollution deposition in Sweden. Both lead concentrations and ^sup 206^Pb/^sup ...207^Pb ratios have been analysed in 31 lakes covering most of Sweden, plus one lake in north-west Russia. Four of the lakes have varved (annually-laminated) sediments. Isotope analysis is a sensitive and effective method to distinguish pollution lead from natural catchment lead and to detect early pollution influence, because the ^sup 206^Pb/^sup 207^Pb ratio in unpolluted background sediments in Sweden was > 1.3, while that of lead from pollution, derived from ores and coal, was < 1.2. The sediments show a consistent picture of past temporal changes in atmospheric lead pollution. These changes include: the first traces of pollution 3,500-3,000 yrs ago; a pollution peak in Greek-Roman Times (about 0 AD); lower lead fall-out between 400 and 900 AD; a significant and permanent increase in atmospheric lead fall-out from about 1000 AD; an increase with the Industrial revolution; a major increase following World War II; the maximum peak in the 1970s; and decreasing fall-out over the last decades. The four varved sediments provide high-resolution records of atmospheric pollution. They reveal pollution peaks about 1200 and 1530 AD which match the history of metal production in Europe. According to the varve records the lead pollution level in the late 1990s had decreased beneath the level of the 1530s. The pollution level 1200 AD was about 35% of the 1980s, when lead pollution was still near its all time high. About 50% of the total accumulated atmospheric lead pollution deposition through time was deposited in the pre-industrial period. The sediments also show a consistent picture of the geographic distribution of atmospheric lead deposition over time, with higher deposition in south Sweden and declining levels to the north, which supports the hypothesis that the main sources of pre-industrial atmospheric lead pollution in Sweden were cultural areas in mainland Europe and Great Britain.PUBLICATION ABSTRACT
Peat cores from ombrotrophic bogs have been used as a valuable archive to study environmental change for over a century. Much of this focus on the peat record has been on biological proxies of ...environmental change, such as pollen and peat-forming macrofossils, but there is growing interest in the geochemical record to study environmental changes. Several studies of long-term peat records in Europe have reconstructed past changes in atmospheric lead pollution, for example, and the general cohesiveness of the results and their agreement with known historical trends in metal production exemplify the best potential of peat geochemistry as an environmental archive. Based on the success with lead, a current emphasis in peat reconstructions is to assess the record of past mercury deposition and results thus far show generally consistent trends, e.g., a pre-anthropogenic mercury accumulation rate of about 0.5–1.5 μg Hg m
−
2
year
−
1
. Despite this general consistency there is increasing concern that there may be diagenetic effects on the quantitative record of some metals, which can be inferred based on a strong relationship between mercury and other organically bound elements and proxies for peat decomposition (C/N ratio). However, it is possible that changes in decomposition and the alteration of some metal records could provide climatic information. A few recent studies show that closer examination of the geochemical matrix, in some cases along with biological proxies, can provide valuable information on landscape changes and climate; for example, partitioning metals into different weight fractions and source regions can be applied to climate studies. The best interpretations of the peat geochemical record in the context of environmental and climate change will likely come when geochemical and biological records are considered simultaneously.
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 (206Pb/207Pb 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.).
Knowledge of natural, prepollution concentrations of heavy metals in forest soils and temporal trends of soil pollution are essential for understanding present-day pollution (ecotoxicological ...assessments) and for establishing realistic goals for reductions of atmospheric pollution deposition (critical loads). Soils not exposed to deposition of atmospheric pollution no longer exist and, for example, present lead (Pb) pollution conditions in northern European soils are a consequence of nearly 4,000 years of atmospheric pollution. We use analyses of Pb concentrations and stable Pb isotopes (206Pb/207Pb ratios) of ombrotrophic peat and forest soils from southern Sweden and a model for Pb cycling in forest soils to derive an estimate for the prepollution concentration of Pb in the mor layer of boreal forest soils and to back-calculate Pb concentrations for the last 5,500 years. While the present-day concentra tions of the mor layer are typically 40−100 μg g-1 (0.25−1.0 g m-2), Pb concentrations of pristine forest mor layers in Sweden were quite low, ≤0.1 μg g-1 (≤1 mg m-2). Large-scale atmospheric pollution from the Greek and Roman cultures (ca. 0 AD) increased Pb concentrations to about 1 μg g-1. Lead (Pb) concentrations increased to about 4 μg g-1 following the increase of metal production and atmospheric pollution in Medieval Europe (ca. 1000 AD).
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