| 1. |
- Bindler, Richard, et al.
(författare)
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Bridging the gap between ancient metal pollution and contemporary biogeochemistry
- 2008
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Ingår i: Journal of Paleolimnology. - : Springer. - 0921-2728 .- 1573-0417. ; 40:3, s. 755-770
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Tidskriftsartikel (refereegranskat)abstract
- Paleolimnology provides long-term data that are often essential for understanding the current state of the environment. Even though there is great potential, paleolimnology is rarely used together with process-related studies to solve issues regarding cycling of elements in the environment. Clearly, this is a drawback because the cycling of many elements, which cause great concern in the present-day environment, was altered long before the advent of monitoring programs. The pioneering work of C.C. Patterson and his colleagues emphasized the importance of a long-term perspective for understanding the current cycling of metals, with a focus on lead, and in particular for estimating background concentrations and human-related impacts in the environment. In Sweden the first traces of atmospheric lead pollution are found in lake sediments dated to about 3500 years ago. The long-term changes in the pollution lead record in lake sediments led us to consider how lead biogeochemistry has changed over time in response to this historical deposition‹where has this lead gone, and how much does this lead contribute to the present-day biogeochemical cycling of lead? How was lead distributed in Œpre-industrial¹ soils or more properly in natural soils not impacted by atmospheric pollution? There are many studies that have examined the effects of increased metal concentrations on soil biota, but what are the appropriate background conditions for comparison? Using lake sediments as our foundation we have analyzed lead, including its stable isotopes, in other environmental compartments, including peat, soil, and a range of boreal forest plant species, to develop a better understanding of the fate of lead derived from long-term pollution. Three important conclusions from our studies in Sweden are: (1) atmospheric lead deposition rates during the 20th century were 100 to as much as 1000 times higher than natural deposition rates a few thousand years ago. Even with stricter emission standards during the past three decades and the resultant reductions in deposition, lead deposition rates today are still 10100 times greater than natural rates. This increase in deposition rates modeled from sediment and peat records is of a similar scale to estimated changes in body burdens of lead in modern versus ancient humans. (2) In Europe about half of the cumulative burden of atmospherically deposited lead was deposited before industrialization. In southern Sweden the cumulative burden of pollution lead during the past 3500 years is 25 g Pb m-2 and in the Œpristine¹ northern parts of the country there is about 1 g Pb m-2. (3) Predicted recovery rates for soils are slow; in the cold climate of Scandinavia, we find that the soil surface (O horizon), where most soil biota reside, retains lead deposited over the past 150500 years. Therefore, although lead deposition rates in Europe, as well as N. America, are only 10% of those a few decades ago, it will take several decades or longer for lead concentrations in soils to respond appreciably. The slow turnover rates for lead in the environment and gradual immobilization of lead in deeper soil mineral horizons also inhibits a loss of lead to surface waters in areas removed from point sources.
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| 2. |
- Bindler, Richard, et al.
(författare)
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Landscape-scale patterns of sediment sulfur accumulation in Swedish lakes
- 2008
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Ingår i: Journal of Paleolimnology. - : Springer Science and Business Media LLC. - 0921-2728 .- 1573-0417. ; 39, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur has played a central role in the acidification of many lakes in Scandinavia and other regions. As part of the research into sulfur cycling, numerous studies have analyzed the sediment record in order to develop insights into past in-lake cycling of sulfur, particularly in the context of reconstructing past deposition rates. Although many of these studies have shown that it is not easy to interpret the sediment record in terms of past sulfur deposition rates, analyses of sulfur in sediment still provide valuable information on the response of lakes to anthropogenic sulfur deposition. Here, we have analyzed sulfur in top and bottom samples from short surface cores (25-35 cm, representing >= 250 years) as well as bulk cores from similar to 110 lakes located throughout Sweden, which were collected during 1986, as well as in more-detailed profiles from six lakes. The lakes with the highest surface sediment concentrations (9-24 mg S g(-1) dry mass) and the highest calculated inventories of 'excess' sulfur (20-180 g S m(-2)) are found in southern Sweden and around one industrial area along the northeastern coast where sulfur deposition rates and lake-water concentrations have been highest. For many lakes in the central and northern inland region it is common that the sediment cores exhibit either no enrichment or even a decline in sulfur concentrations in near-surface sediments, which we suggest was the pre-pollution norm for lakes. Although interpreting sulfur sediment profiles is problematic for reconstructing deposition, a more-comprehensive spatial sampling approach shows that there is a good geographic agreement between sulfur deposition, lake-water chemistry and sediment sulfur accumulation.
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| 3. |
- Bindler, Richard, et al.
(författare)
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Widespread waterborne pollution in central Swedish lakes and the Baltic Sea from pre-industrial mining and metallurgy
- 2009
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 157, s. 2132-2141
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Tidskriftsartikel (refereegranskat)abstract
- Metal pollution is viewed as a modern problem that began in the 19th century and accelerated through the 20th century; however, in many parts of the globe this view is wrong. Here, we studied past waterborne metal pollution in lake sediments from the Bergslagen region in central Sweden, one of many historically important mining regions in Europe. With a focus on lead (including isotopes), we trace mining impacts from a local scale, through a 120-km-long river system draining into Malaren - Sweden’s third largest lake, and finally also the Baltic Sea. Comparison of sediment and peat records shows that pollution from Swedish mining was largely waterborne and that atmospheric deposition was dominated by long-range transport from other regions. Swedish ore lead is detectable from the 10th century, but the greatest impact occurred during the 16th-18th centuries with improvements occurring over recent centuries, i.e., historical pollution > modern industrial pollution.
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| 4. |
- Englund, Edvard, et al.
(författare)
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Modeling fallout of anthropogenic I-129
- 2008
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 42:24, s. 9225-9230
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Tidskriftsartikel (refereegranskat)abstract
- Despite the relatively well-recognized emission rates of the anthropogenic 128I, there is little knowledge about the temporal fallout patterns and magnitude of fluxes since the start of the atomic era at the early 1940s.We here present measurements of annual 129I concentrations in sediment archives from Sweden and Finland covering the period 1942-2006. The results revealed impression of 129I emissions from the nuclear reprocessing facility at Sellafield and La Hague and a clear Chernobyl fallout enhancement during 1986. In order to estimate relative contributions from the different sources, a numerical model approach was used taking into accountthe emission rates/ estimated fallout, transport pathways, and the sediment system. The model outcomes suggest a relatively dominating marine source of 129I to north Europe compared to direct gaseous releases. A transfer rate of 129I from sea to atmosphere is derived for pertinent sea areas (English Channel, Irish Sea, and North Sea), which is estimated at 0.04 to 0.21 y-1.
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| 5. |
- Guhrén, Matilda, et al.
(författare)
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Liming placed in a long-term perspective: a paleolimnological study of 12 lakes in the Swedish liming program
- 2007
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Ingår i: Journal of Paleolimnology. - : Springer Science and Business Media LLC. - 0921-2728 .- 1573-0417. ; 37:2, s. 247-258
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Tidskriftsartikel (refereegranskat)abstract
- Since the 1970s liming has been practised on a large scale in Sweden to mitigate acidification and several thousand lakes and streams are limed repeatedly. The Swedish monitoring program ISELAW (Integrated Studies of the Effects of Liming Acidified Waters) studies the long-term effects of liming. This paper summarizes the paleolimnological part of the program. Sediment cores from 12 lakes were analysed to study the development of the lakes from pre-industrial time until the present, and address questions about natural conditions and the effects of early human impact, acidification, and liming. Diatoms were used to reconstruct the pH history and to study shifts in species composition due to acidification and liming. Analyses of lead and spheroidal carbonaceous particles were applied for indirect dating and as indicators of the atmospheric deposition of pollutants associated with acid rain. Pollen analysis was performed in eight of the lakes to study the vegetation and agricultural history. The natural pH (prior to human disturbance) was between 5.3 and 6.5 in the eight lakes where the complete post-glacial sediment sequence was recovered. Pollen from anthropochores and apophytes indicated early agricultural land use in the vicinity of the lakes from 1000 to 2000 years ago, and pH increased with land use in six of these lakes. Five of the lakes have been acidified during recent decades, and in all 12 lakes some effects of liming were recorded in the diatom assemblage. The lakes show different responses to liming, including a return to a pre-acidification diatom composition or a shift to a state previously not recorded in the lake’s histories. This study accentuates the complexity of biological response to acidification and liming, and highlights the importance of historical perspectives to assess the current state of a lake’s ecosystem and to establish adequate restoration goals.
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| 6. |
- Gälman, Veronika, 1969-, et al.
(författare)
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A comparison of sediment varves (1950–2003 AD) in two adjacent lakes in northern Sweden
- 2006
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Ingår i: Journal of Paleolimnology. - Dordrecht : Kluwer. - 0921-2728 .- 1573-0417. ; 35, s. 837-853
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Tidskriftsartikel (refereegranskat)abstract
- Koltjärnen and Nylandssjön are two closely situated lakes (<2 km apart) in northern Sweden. During the past century, distinct varved sediments have formed in these lakes. Nylandssjön has two varved, deep basins. Since lake and catchment characteristics superficially appear very similar for the two lakes and they are exposed to the same climate, one would expect the sediment varves to be similar. This investigation compares the varves in the two deep basins of Nylandssjön, and in the two lakes. The comparison of basins of Nylandssjön shows that varve thickness, water content and annual accumulation rates of organic matter and nitrogen are correlated for the period (1970–2003). The grey-scale curves are only clearly similar in about 50% of the varves. In the between-lake comparison varve thickness, water content and annual accumulation rates of organic matter and nitrogen are correlated for the period (1950–1996). However, the annual accumulation rates of dry mass, minerogenic matter and biogenic silica differ between the lakes, as well as within-varve successions in grey-scale. A general explanation to the differences is that the prerequisites for varve formation are not totally similar because of differences in catchment size, catchment- to-lake material fluxes, lake productivity and land-use influence. This study illustrates the complex relationships that exist between a lake, its catchment, in-lake productivity and formation of sediment varves. As a consequence, we must not apply a too simplistic view of the potential of varves as past climatic indicators, especially if the lakes are affected by land-use.
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| 7. |
- Gälman, Veronika, et al.
(författare)
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Carbon and nitrogen loss rates during aging of lake sediment : Changes over 27 years studied in varved lake sediment
- 2008
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Ingår i: Limnology and Oceanography. - Waco, Tex. : American Society of Limnology and Oceanography. - 0024-3590 .- 1939-5590. ; 53:3, s. 1076-1082
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Tidskriftsartikel (refereegranskat)abstract
- We used a collection of ten freeze cores of annually laminated (varved) lake sediment from Nylandssjön 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.
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| 8. |
- Gälman, Veronika, et al.
(författare)
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Kiselalger som miljöindikatorer i små vattendrag : miljötillståndet i bäckar i Västerbotten år 2007 enligt analys av epilitiska kiselalger
- 2009
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Rapport (populärvet., debatt m.m.)abstract
- Analys av kiselalger från stenar i 73 bäckar i Västerbotten har använts för att bestämma bäckvattnets status vad gäller surhet och näringsgrad/organisk förorening. Provtagningen gjordes under sensommaren/hösten 2007 med en provtagare som kallas ”Stone Brusher”. Kiselalgsanalyserna utfördes enligt metod SS-EN 14407 (SIS 2005) och Naturvårdsverkets handbok för miljöövervakning. Surhetsindex ACID resp IPS index för näringsgrad/organisk förorening bestämdes enligt anvisningarna, och utvärderingen gjordes enligt de senaste bedömningsgrunderna (Naturvårdsverket 2007). Av de 73 bäckarna fick 6 bäckar bedömningen Alkaliskt vatten, 27 bäckar Nära neutralt vatten, 27 bäckar Måttligt surt vatten, 10 bäckar Surt vatten och 3 bäckar Mycket surt vatten. Således dominerar bäckar med nära neutralt eller måttligt surt vatten. De alkaliska bäckarna är belägna i kustens jordbruksbygd eller är kalkade gruvbäckar. Några av de sura bäckarna flyter genom sulfidrika jordar vid kusten och andra är sura av organiska syror (bäckar med mycket brunt vatten). De tre bäckarna som kiselalgerna klassificerar som mycket sura ligger i samma område i Nordmaling, och dessa bäckar är inte särskilt bruna. När det gäller statusbedömningen enligt näringsgrad/organisk förorening (IPS index) fick 62 bäckar bedömningen Hög status, 10 bäckar God status, och 1 bäck Måttlig status. Överlag är således de undersökta bäckarna inte påverkade eller ganska lite påverkade av näringsämnen. De bäckar som inte uppnår högsta status är främst jordbruksbäckar. För ett par bäckar i Lycksele kan påverkan av näringsämnen ha en naturlig geologisk förklaring. Undersökningen visar att miljöövervakning med kiselalger är en väl fungerande metod. Samtidigt visar undersökningen att miljöövervakning med hjälp av kiselalger enligt Naturvårdsverkets anvisningar är en metod för specialister. I andra delen av rapporten visar vi med hjälp av simuleringstester att metoden kan förenklas. Det är i de allra flesta bäckar inte nödvändigt att räkna mera än en bråkdel av det antal skal (400 st) som föreskrivs i anvisningarna. Det är inte heller meningsfullt att ägna tid åt att bestämma kiselalger som bara uppträder med någon procent i preparaten eftersom dessa taxa inte spelar någon avgörande roll för statusbedömningarna. Man behöver inte heller splittra upp arter i varieteter och former i den grad som anvisningarna förespråkar. Faktum är att ett begränsat antal dominerande arter bestämmer vilken status en bäck får. Vi förespråkar att en enklare modell för kiselalgsbaserad miljöövervakning utarbetas. Det finns redan för många exempel på att alltför specialiserade och ambitiösa miljöövervakningsmetoder inte blir långsiktigt hållbara – de läggs ned med sina skapare innan tidsserierna egentligen blir utvärderingsbara. I sista delen av rapporten pekar vi på en kompletterande, eller om man så vill, alternativ modell för miljöövervakning i rinnande vatten, nämligen närinfraröd spektroskopi (NIRS) på det epilitiska materialet. NIRS är en sedan länge etablerad, enkel och billig kvalitetskontrollmetod inom industrin. Allt talar för att den också skulle kunna bli det inom miljöövervakningen.
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| 9. |
- Gälman, Veronika, 1969-, et al.
(författare)
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The role of iron and sulfur in the visual appearance of lake sediment varves
- 2009
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Ingår i: Journal of Paleolimnology. - : Springer Netherlands. - 0921-2728 .- 1573-0417. ; 42:1, s. 141-153
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Tidskriftsartikel (refereegranskat)abstract
- Easily discernible sediment varves (annual laminations) may be formed in temperate zone lakes, and reflect seasonal changes in the composition of the accumulating material derived from the lake and its catchment (minerogenic and organic material). The appearance of varves may also be influenced by chemical processes. We assessed the role of iron (Fe) and sulfur (S) in the appearance of varves in sediments from Lake Nylandssjön in northern Sweden. We surveyed Fe in the lake water and established whether there is internal transport of Fe within the sediment. We used a unique collection of seven stored freeze cores of varved sediment from the lake, collected from 1979 to 2004. This suite of cores made it possible to follow long-term changes in Fe and S in the sediment caused by processes that occur in the lake bottom when the sediment is ageing. We compared Fe and S concentrations using X-ray fluorescence spectroscopy (XRF) in specific years in the different cores. No diagenetic front was found in the sediment and the data do not suggest that there is substantial vertical transport of Fe and S in the sediment. We also modeled Fe and S based on thermodynamic, limnological, and sediment data from the lake. The model was limited to the five components H+, e-, Fe3+, SO42-, H2CO3 and included the formation of solid phases such as Fe(OH)3 (amorphous), FeOOH (aged, microcrystalline), FeS and FeCO3. Modeling showed that there are pe (redox) ranges within which either FeS or Fe(OH)3/FeOOH is the only solid phase present and there are pe ranges within which the two solid phases co-exist, which supports the hypothesis that blackish and grey-brownish layers that occur in the varves were formed at the time of deposition. This creates new possibilities for deciphering high-temporal-resolution environmental information from varves.
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| 10. |
- Gälman, Veronika, 1969-
(författare)
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Varved lake sediments and diagenetic processes
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Varved (annually laminated) sediments are of great interest for inference of past environmental conditions, as they provide dated records with high time resolution. After deposition, the sediment varves are affected by diagenesis; i.e., chemical, physical and biological changes that occur within the sediment. An important premise when reconstructing past environmental conditions using lake sediments is that the signal of interest is preserved in the sediment. In this thesis I have used a unique collection of ten stored freeze cores of varved lake sediment from Nylandssjön in northern Sweden, collected from 1979 to 2007. The suite of cores made it possible to follow long-term (up to 27 years) changes in iron (Fe), sulfur (S), carbon (C), nitrogen (N), δ13C and δ15N in the sediment caused by processes that occur in the lake bottom as the sediment ages. The sediment geochemistry and resulting changes were followed in years for which there are surface varves in the core series. Fe and S concentrations analyzed by X-ray fluorescence spectroscopy showed no diagenetic front in the sediment and the data do not suggest a substantial vertical transport of Fe and S in the sediment. A model based on thermodynamic, limnological, and sediment data from the lake, showed that there are pe (redox) ranges within which either FeS (reduced specie) or Fe(OH)3/FeOOH oxidized species) is the only solid phase present and there are pe ranges within which the two solid phases co-exist. This supports the hypothesis that blackish and grey-brownish Fe-layers that occur in the varves were formed at the time of deposition. C and N analyzed with an elemental analyzer showed that within the first five years after deposition the C concentration of the sediment decreased by 20% and N by 30%, and after 27 yr in the sediment, there was a 23% loss of C and 35% loss of N. The C:N ratio increased with increasing age of the sediment; from ~ 10 in the surface varves to ~12 after 27 years of aging. δ13C and δ15N analyzed on a mass spectrometer showed that δ13C increased by 0.4-1.5‰ units during the first five years, after that only minor fluctuations in δ13C were recorded. Another pattern was seen for δ15N, with a gradual decrease of 0.3-0.7‰ units over the entire 27-year-period. The diagenetic changes in the stable isotope values that occur in Nylandssjön are minor, but they are of about the same magnitude as the variation in the isotopic signal in the varves deposited between 1950-2006. My results show that diagenesis does not change the visual appearance of the varves, except for varve thickness; the varves get thinner as the sediment ages. As the color of Fe in the varves likely reflects the environmental conditions at the time of deposition this creates possibilities for deciphering high-temporal-resolution information of past hypolimnetic oxygen conditions from varves. My findings on C, N, δ13C and δ15N will have implications for interpretations of paleolimnological data. The diagenetic effects should be carefully taken into consideration when C, N, δ13C and δ15N in sediment cores are used to study organic matter sources or paleoproductivity, in particular when dealing with relatively small and recent changes. In addition to the significance of diagenetic effects on sediment parameters, a comparison of the varves in Nylandssjön and the adjacent lake Koltjärnen, and the two deep basins of Nylandssjön show that subtle features in the lakes and their catchments affect the appearance of the varves, which make interpretation of varves complicated.
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