Deposition In Finland Research Articles

Pike Mercury Concentration in Small Boreal Headwater Lakes During Four Decades of Regional and Local Changes

We measured the total mercury (THg) concentration in the muscle of northern pike (Esox lucius L.) from 12 boreal headwater lakes once per decade during the 1980s to 2010s. Relations of pike THg to regional environmental changes, such as reduction of acid deposition and increase in water colour (i.e. browning), were examined as well as the effects of local lake-specific changes caused by introduced beavers (Castor canadensis) and intensive fishing of pike. No consistent decrease in pike THg took place during 1983–2013 despite the reductions in mercury emissions from European sources since the 1990s and the associated decreased mercury deposition in Finland. In most of the lakes, individual pike exceeded the recommended limit for human consumption (1 mg kg−1, wet weight). The highest THg levels were recorded in 2002 following intensive browning of the lakes in the 1990s in connection with decreased sulphate deposition. The effects of acid deposition were only seen as the highest pike THg in the two most acidic lakes in the early 1980s. After taking length effects into account, pike THg had a negative relationship with growth (i.e. growth dilution), but a positive relationship with water colour, iron, nutrients and maximum lake depth. Females grew faster and had lower THg than males. Pike THg was elevated in beaver-impacted lakes. Experimental removal of pike from three study lakes during 2005–2013 resulted in a decrease of pike THg. These findings emphasize the significance of local abiotic and biotic drivers when interpreting the regional long-term trends in pike THg.

A mining industry overview of cobalt in Finland: exploration, deposits and utilization

Finland has a significant role in the European Union cobalt supply, with the largest known cobalt resources and only cobalt-producing mines in Europe. In addition, Finland is a globally significant producer of refined cobalt. However, Finland, along with the rest of Europe, is strongly dependent on cobalt imports. Recycled cobalt covers a small fraction of the country's demand, as well as that of the rest of Europe. Most of the cobalt deposits in Finland can be grouped into five genetic types (± subtypes). The orthomagmatic and Outokumpu types have been among the most important sources of cobalt in Finland. The Talvivaara type hosts the largest known cobalt resource in Europe, mostly in the Terrafame Sotkamo deposit. The most common cobalt minerals in the Finnish deposits are sulfides, and to a lesser extent sulfarsenides. These are concentrated by froth flotation, and the concentrates treated in Finnish cobalt refineries. An exception to this is the Terrafame Sotkamo mine, where bio-heap leaching technology is utilized for metal recovery, and metalliferous liquid is processed to battery-grade chemicals. Assessment of undiscovered mineral resources, prospectivity modelling, the exploration history and recent discoveries highlight the exploration potential for several types of Co-enriched mineral deposits in Finland. Thematic collection: This article is part of the energy-critical metals for a low carbon transition collection available at: https://www.lyellcollection.org/topic/collections/critical-metals

Re-Os isotope geochemistry of komatiite-hosted Ni-Cu-PGE deposits in Finland

We have studied the Re-Os isotope systematics of komatiite-related Ni-Cu-PGE sulfide deposits in Finland, including the Archean Ruossakero Ni-(Cu), Vaara Ni-(Cu-PGE), Tainiovaara Ni-(Cu-PGE) deposits and Ni-PGE sulfide mineralization related to a dunitic body at Tulppio, and the Paleoproterozoic Lomalampi PGE-(Ni-Cu) deposit. We analyzed chromite separates from both mineralized and non-mineralized komatiitic rocks, bulk-sulfide separates, and country-rock black schist from one deposit, and for comparison, chromite separates from non-mineralized Archean komatiitic rocks from the Kovero and Kuhmo greenstone belts.We have observed open-system behavior of sulfides in three deposits, with their Re-Os isotope compositions indicating resetting at ca. 1.83–1.87 Ga by metamorphic events related to the Svecofennian orogeny. Most of the chromite separates, especially those with >10 ppb Os, retain their primary isotope compositions with near-chondritic initial 187Os/188Os ratios, indicating that their Os was derived from a mantle source with a chondritic Re-Os isotope evolution. These include the Vaara deposit, which yielded a chromite Re-Os isochron age of 2719 ± 140 Ma and low initial γOs of −1.2 ± 0.02, in spite of the evidence for the presence of mass-independent S isotope fractionation in this deposit, suggesting a low-Os, sulfur-bearing contaminant. In the case of the Lomalampi deposit, chromites yield an isochron with an age of 2058 ± 93 Ma and initial γOs of +0.9 ± 0.02, consistent with earlier isotope data from Central Lapland komatiites. However, one chromite from a mineralized cumulate gave a γOs(2050 Ma) value of +24 ± 18, indicating a minor/moderate degree of crustal contamination involving material from country rock black schists. This is also supported by earlier S isotope data. In the Archean Tainiovaara deposit, chromite also suggests crustal contamination (γOs + 13 ± 1), but country rocks are Os-poor Archean gneisses, leaving the source of radiogenic Os unclear, though it is possible that contamination occurred at a greater depth. Our results also provide evidence that the Re-Os age of the Ruossakero deposit is ca. 2.9 Ga, with the deposit likely representing komatiitic magmatism that is older than the komatiitic magmatism elsewhere in Finland. Re-Os results also confirmed that the mineralized Tulppio Dunite is Archean in age.

Ni-(Cu-PGE) deposits in Finland – Geology and exploration potential

Several types of nickel sulphide deposits occur in Finland. Some of them are also important sources of Cu, Co and PGE. The main deposit types are related to Archaean and Palaeoproterozoic mafic to ultramafic rocks, Palaeoproterozoic metamorphosed black shales of the Talvivaara type, or the ultramafic and metasomatic calc-silicate rocks of the ophiolitic Outokumpu association. Several komatiite-hosted Ni-Cu-PGE deposits have been discovered in the Archaean and Paleoproterozoic greenstone belts in northern and eastern Finland, but only one has been briefly mined, in 1989. Many 2.44Ga Palaeoproterozoic mafic-ultramafic layered intrusions in Finland host contact-type PGE-Ni-Cu deposits and significant reef-type PGE deposits; typically the Ni resources are of low grade but large tonnage. The mafic-ultramafic magmatism at ca. 2.06Ga produced significant Ni-Cu-PGE resources in the Central Lapland greenstone belt, including the Kevitsa and Sakatti deposits. The Svecofennian domain in central and southern Finland contains hundreds of small, ca. 1.88Ga, mafic-ultramafic orogenic intrusions; many of these host nickel mineralization. Nickel exploration potential was evaluated in general, based on identification of critical factors within a mineral system framework and a quantitative assessment of the potential occurrence of undiscovered nickel resources. The MgO content of the parental magma was estimated for 28 deposits: 6 komatiite-hosted occurrences and 22 Svecofennian orogenic intrusions. The estimated MgO content of the parental magmas for the selected deposits varies from around 7% to 15% in basaltic to komatiitic basalt systems and up to 30% in more magnesian komatiitic systems; the Ni/Cu value varies mostly between 0.7 and 12, correlating in general positively with the MgO content of the magma. Exceptionally high or low Ni/Cu values in some deposits may result from, for example, copper loss during post-magmatic processes (serpentinization and/or metamorphism) or part of the sulphide ore (zoned by the Ni/Cu value) still being unknown. Recent advances in understanding of komatiites in Finland indicates high exploration potential for nickel within the Paleoproterozoic komatiitic formations, which typically are also significantly enriched in Cu and PGE. However, the quantitative assessment of undiscovered nickel resources in Finland suggests that the contact-type Ni-Cu-PGE deposits hosted by 2.44Ga mafic-ultramafic layered intrusions in northern Finland have the greatest potential for hosting undiscovered resources among the assessed nickel deposit types; these occur within restricted areas, resulting in a high deposit density. Finally, considerable nickel resources might exist in undiscovered Talvivaara-, Kevitsa- or Sakatti-type deposits. These deposit types should be assessed as soon as more geological information becomes available.

Site index changes of Scots pine, Norway spruce and larch stands in southern and central Finland

The annual growth of the Finnish forests has doubled in less than a century but the reasons for the increase have been a subject of much debate. Site index aggregates the mid- to long-term impacts of variable edaphic and climatic factors on site productivity and is an important characteristic with regard to the ongoing environmental changes. We quantified changes of site index in Finland over time by applying a new approach developed in our previous study in Germany. A large data base for Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and larch (Larix spp.) was available from the network of long-term growth and yield experiments in southern and central Finland. For all tree species, site indices fluctuated over time, i.e. they slightly decreased in the 1970s, followed by an increasing trend in the 1980s and a decline again in the 1990s. Apparently, the only significant change was a change point indicated for Scots pine around the year 1944; however, indication was weak due to notable limitations of the database during the respective period. Interestingly, the result of this study in Finland differs from central Europe, where Norway spruce site productivity has displayed a considerable increase since the 1950s. Potentially, the low nitrogen deposition in Finland may be of major importance accounting for the divergent changes in site productivity between Finland and central Europe. Thus, the results indicate that a large share of the growth increase in the Finnish forests might actually be due to altered management.

Seismic reflection surveys in glaciofluvial deposits in Finland

ABSTRACTShallow seismic reflection surveys were conducted at five different locations in central Finland during the period of 2008–2011 in order to test the applicability of this method and different seismic energy sources in providing accurate images of the underlying seismic structure and geology in unconfined and confined esker aquifers. The depth of the aquifers varied from 15 m to 140 m. Reflections from the water table and the bedrock were generally detected. In the deepest aquifers, several features of the inner structure were visible. In the shallowest aquifer (15 m thick), seismic detection of the stratigraphic units proved difficult. Analysis of the theoretical travel times and the shallow structure suggested that a higher frequency seismic source might have been needed. In the deeper aquifers, reflections near the bedrock were detected, but information regarding their thicknesses could not be obtained. An unsaturated layer with a thickness of 25 m did not completely attenuate the seismic signal, and reflections from the water table and bedrock (~80 m) could still be obtained. For the amount of explosives and the type of vibrator used in this study, explosives generally produced clearer reflections due to the higher signal‐to‐noise ratio compared with the vibrator source. On the other hand, shot‐to‐shot fluctuations in signal‐to‐noise ratio and source irreproducibility were found to be greater for explosives than for the vibrators. Loose lake sediments above the aquifer inhibited seismic energy transmission to the bedrock. In such situations, the use of explosives is recommended in order to obtain clearer reflections from the subsurface soil boundaries.

Deposition of atmospheric 210Pb and total beta activity in Finland

The seasonal and regional variation of the atmospheric 210Pb deposition in Finland was studied. The 210Pb activity concentration in precipitation shows a decreasing trend from southeastern Finland north-westwards. An average deposition of 40 Bq/m2 during a 12 months period was observed. The deposition of 210Pb shows a seasonal variation with minimum in spring and maximum in autumn and winter. The specific activity of 210Pb (activity of 210Pb per unit mass of stable lead) in the atmosphere has returned to the level prior to World War II owing to the reduced lead emissions into the atmosphere.

Hazardous organic compounds in biogas plant end products—Soil burden and risk to food safety

The end products (digestate, solid fraction of the digestate, liquid fraction of the digestate) of ten biogas production lines in Finland were analyzed for ten hazardous organic compounds or compound groups: polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCB(7)), polyaromatic hydrocarbons (PAH(16)), bis-(2-ethylhexyl) phthalate (DEHP), perfluorinated alkyl compounds (PFCs), linear alkylbenzene sulfonates (LASs), nonylphenols and nonylphenol ethoxylates (NP+NPEOs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA). Biogas plant feedstocks were divided into six groups: municipal sewage sludge, municipal biowaste, fat, food industry by-products, animal manure and others (consisting of milling by-products (husk) and raw former foodstuffs of animal origin from the retail trade). There was no clear connection between the origin of the feedstocks of a plant and the concentrations of hazardous organic compounds in the digestate. For PCDD/Fs and for DEHP, the median soil burden of the compound after a single addition of digestate was similar to the annual atmospheric deposition of the compound or compound group in Finland or other Nordic countries. For PFCs, the median soil burden was somewhat lower than the atmospheric deposition in Finland or Sweden. For NP+NPEOs, the soil burden was somewhat higher than the atmospheric deposition in Denmark. The median soil burden of PBDEs was 400 to 1000 times higher than the PBDE air deposition in Finland or in Sweden. With PBDEs, PFCs and HBCD, the impact of the use of end products should be a focus of further research. Highly persistent compounds, such as PBDE- and PFC-compounds may accumulate in agricultural soil after repeated use of organic fertilizers containing these compounds. For other compounds included in this study, agricultural use of biogas plant end products is unlikely to cause risk to food safety in Finland.

Assessment of doses to game animals in Finland

A study was carried out to assess the dose rates to game animals in Finland affected by the radioactive caesium deposition that occurred after the accident at the Chernobyl nuclear power plant in Ukraine in 1986. The aim of this assessment was to obtain new information on the dose rates to mammals and birds under Finnish conditions. Dose rates were calculated using the ERICA Assessment Tool developed within the EC 6th Framework Programme. The input data consisted of measured activity concentrations of 137Cs and 134Cs in soil and lake water samples and in flesh samples of selected animal species obtained for environmental monitoring. The study sites were located in the municipality of Lammi, Southern Finland, where the average 137Cs deposition was 46.5 kBq m−2 (1 October 1987). The study sites represented the areas receiving the highest deposition in Finland after the Chernobyl accident. The selected species included moose (Alces alces), arctic hare (Lepus timidus) and several bird species: black grouse (Tetrao tetrix), hazel hen (Bonasia bonasia), mallard (Anas platurhynchos), goldeneye (Bucephala clangula) and teal (Anas crecca). For moose, dose rates were calculated for the years 1986–1990 and for the 2000s. For all other species, maximal measured activity concentrations were used. The results showed that the dose rates to these species did not exceed the default screening level of 10 μGy h−1 used as a protection criterion. The highest total dose rate (internal and external summed), 3.7 μGy h−1, was observed for the arctic hare in 1986. Although the dose rate of 3.7 μGy h−1 cannot be considered negligible given the uncertainties involved in predicting the dose rates, the possible harmful effects related to this dose rate are too small to be assessed based on current knowledge on the biological effects of low doses in mammals.

Rock magnetic investigations constraining relative timing for gold deposits in Finland

Rock magnetic investigations constraining relative timing for gold deposits in Finland

Overview of strontium-89,90 deposition measurements in Finland 1963–2005

In Finland the deposition of strontium-89 ( 90Sr) and strontium-90 ( 90Sr) has been monitored since the early 1960s. The measured cumulative 90Sr deposition in 1963–2005 is on average 1200 Bq m −2, of which 150 Bq m −2 originates from the Chernobyl accident. Adding to this the deposition in 1945–1962 produces a value of 2040 Bq m −2 for the cumulative deposition in Finland. The nuclear explosion-derived deposition up to 1985 obtained in this study, 1850 Bq m −2, is in good agreement with the zonal 90Sr deposition of 1740 Bq m −2 in the 60°N–70°N latitude band estimated by UNSCEAR. The regional deposition patterns of 89Sr and 90Sr following the Chernobyl accident resemble those of the refractory nuclides such as 239,240Pu and 95Zr. The total deposition of Chernobyl-derived 90Sr in Finland was about 5.3 × 10 13 Bq. This activity corresponds to 0.027% of the reactor core inventory and 0.66% of the atmospheric emissions from the accident. The corresponding figures for 89Sr are 4.5 × 10 14 Bq, 0.023% and 0.56%, respectively.

Long-term changes in nitrogen deposition in Finland (1990–2006) monitored using the moss Hylocomium splendens

Nitrogen deposition in Finland was investigated on the basis of the nitrogen concentration in the forest moss, Hylocomium splendens, collected during heavy metal moss surveys carried out in 1990, 1995, 2000, and 2005/06. Significant regional differences were found in the nitrogen concentrations in mosses. The concentrations were the highest in the southern part of the country in all the surveys, with a decreasing trend on moving northwards. The mean concentrations in the surveys were 1.07%, 1.00%, 0.89% and 0.92%. In general, the concentrations in mosses reflected nitrogen deposition at the level of the whole country. However, they did not correlate very well with the modelled nitrogen deposition because of the high local variation in the nitrogen concentration in H. splendens. One reason for the high variation was the effect of the structure of the tree stand on nitrogen concentrations in H. splendens.

Modelling the hydro-geochemistry of acid-sensitive catchments in Finland under atmospheric deposition and biomass harvesting scenarios

The dynamic hydro-geochemical Model of Acidification of Groundwater in Catchments (MAGIC) was used to predict the response of 163 Finnish lake catchments to historic and future atmospheric deposition (1880–2100) and future tree harvesting practices. Deposition was assumed to follow current legislated European emission reduction policies (CLe) and a scenario based on maximum (technically) feasible reductions (MFR). Future harvesting was assumed to shift from stem-only harvesting (SOH) to whole-tree harvesting (WTH) owing to the potential increased utilisation of biofuels. Despite the modest changes in atmospheric deposition under CLe (compared to current day), these reductions are predicted to halt the decline in soil base saturation; however, further reductions are required to improve soil and lake water chemistry. The MFR scenario predicted a significant long-term improvement in soil base saturation leading to continued long-term recovery in surface waters (all lakes with ANC > 0 by 2100). However under the WTH scenario, significant long-term impacts (re-acidification) were predicted for soil and surface water chemistry (14 lakes with ANC < 0 by 2100). To some extent the long-term negative impacts were reduced under MFR, indicating that increased utilisation of biofuels will necessitate ‘trading emissions for timber’, or soil amendment, to maintain ecosystem quality and sustainable forest growth. The current practice of SOH is close to the sustainable maximum harvesting under current (legislated) atmospheric deposition in Finland.

Americium and curium deposition in Finland from the Chernobyl accident

Summary 241Am and 244Cm were analysed from peat samples collected in Finland immediately after the Chernobyl accident. The separation method included co-precipitation, anion exchange and extraction chromatography. Activities of 241Am and 244Cm were measured by alpha spectrometry. The activity of Chernobyl-derived 241Am varied between 0.0115 and 9.32 Bq/m2 and that of 244Cm from &lt; 0.002 to 1.97 Bq/m2 (reference date 1.5.1986). The origin of 241Am in Finland is predominantly from atmospheric nuclear tests. However, the geographical distribution of Chernobyl-americium is uneven and depending on a location even 100% of 241Am in peat originated from the Chernobyl accident. The deposition pattern of Chernobyl-derived 241Am and 244Cm resembles that of other refractory nuclides, such as 95Zr, 141Ce and 239,240Pu.

Element accumulation in boreal bryophytes, lichens and vascular plants exposed to heavy metal and sulfur deposition in Finland

Macronutrient (N, P, K, Mg, S, Ca), heavy metal (Fe, Zn, Mn, Cu, Ni, Cd, Pb) and Al concentrations in understorey bryophytes, lichens and vascular plant species growing in Scots pine forests at four distances from the Harjavalta Cu–Ni smelter (0.5, 2, 4 and 8 km) were compared to those at two background sites in Finland. The aim was to study the relationship between element accumulation and the distribution of the species along a pollution gradient. Elevated sulfur, nitrogen and heavy metal concentrations were found in all species groups near the pollution source. Macronutrient concentrations tended to decrease in the order: vascular plants>bryophytes>lichens, when all the species groups grew on the same plot. Heavy metal concentrations (except Mn) were the highest in bryophytes, followed by lichens, and were the lowest in vascular plants. In general, vascular plants, being capable of restricting the uptake of toxic elements, grew closer to the smelter than lichens, while bryophytes began to increase in the understorey vegetation at further distances from the smelter. A pioneer moss ( Pohlia nutans) was an exception, because it accumulated considerably higher amounts of Cu and Ni than the other species and still survived close to the smelter. The abundance of most of the species decreased with increasing Cu and Ni concentrations in their tissues. Cetraria islandica, instead, showed a positive relationship between the abundance and Cu, Ni and S concentrations of the thallus. It is probable that, in addition to heavy metals, sporadically high SO 2 emissions have also affected the distribution of the plant species.

Long-term changes of acidifying deposition in Finland (1973–2000)

The long-term changes of acidifying deposition in Finland during the period 1973–2000 were studied using bulk deposition data from 19 stations belonging to the national monitoring network. The regional-scale approach (southern, central and northern Finland) was used for trend assessment with respect to implementation of European sulphur (S) emission reduction amendments involving deposition changes prior to (1973–1985) and after (1986–2000) the agreements (S protocols in 1985 and 1994). There were no marked changes in sulphate deposition between the 1970s and 1980s and consistent trends in 1973–1985 were not observed. Deposition of nitrogen (N) compounds, particularly NO 3–N, were increasing between the 1970s and 1980s. Deposition of base cations exhibited a slight decline throughout the 1970s and 1980s. Decrease of calcium and magnesium deposition without corresponding decrease in sulphate resulted in increased acidifying potential (AP) of deposition. Due to successful implementation of S (and N) emission reduction measures, sulphate deposition has decreased substantially (30% in northern and up to 60% in southern Finland) since the late 1980s. N deposition also decreased, but less than S deposition. Base cation deposition has also declined substantially, but this decline appeared to be leveling off during the 1990s, accounting for the decrease of AP in deposition. The observed deposition pattern is in agreement with the on-going biochemical recovery of acidified small Finnish lakes taking place since the early 1990s.

A Review of Gold Mineralization Styles in Finland

A wide range of styles of gold mineralization has been recognized in Finland, including orogenic, metamorphosed epithermal, skarn- or epigenetic ironstone-hosted, intrusion-related (nonskarn), massive sulfide-hosted, paleoplacer, and placer deposits. Gold production in the past was principally as a byproduct from the mining of Paleoproterozoic base-metal massive sulfide deposits. This situation has changed during the last decade with the closure of some base metal mines and the commencement of production from recently discovered, gold-only deposits. Gold mineralization occurred during distinct episodes of crustal evolution in Finland. Several late-Archean greenstone belts in the Karelian craton in eastern and northern Finland contain orogenic gold deposits dated at about 2.75 to 2.70 Ga, suggesting a coherent and pervasive tectonic and metallogenic event. In the Paleoproterozoic, low-grade ( The main accretionary stage of the Svecofennian orogeny in Finland culminated with metamorphism and deformation between 1.89 and 1.86 Ga. During that time, intrusion-related Au-Cu mineralization took place in both syntectonic porphyry stocks and their wall rocks in and close to the Archean-Proterozoic margin. Orogenic gold mineralization took place at or slightly after the metamorphic peak throughout the Svecofennian domain, possibly also overprinting massive-sulfide and intrusion-related occurrences. It is notable that the largest orogenic deposits are located within discrete plutons, rather than hosted by supracrustal sequences. This may be a consequence of the rheological contrasts between plutons and the supracrustal lithologies. The Paleoproterozoic Lapland domain in the northern part of the country records a protracted and complicated evolution involving multiple episodes of rifting, magmatism, sedimentation, and alteration, culminating at around 1.9 Ga with the collision of the Karelian craton, the Svecofennian fold belt to the south, and the Kola craton to the north. These deformational events led to orogenic gold mineralization throughout the Proterozoic greenstone belts of northern Finland at about 1.89 to 1.86 Ga, during and soon after the peak of metamorphism and deformation. Skarnlike or epigenetic ironstone-hosted deposits were also formed during the orogeny, in the western and southwestern parts of the Lapland domain, probably somewhat later, at around 1.86 Ga. The most favorable sites for mineralization are regionally extensive zones of early albitization that predate gold mineralization. The deposition of molasselike sediments during the terminal stages of the Svecofennian orogeny and weathering of both orogenic and syngenetic sulfide mineralization, also prior to 1.8 Ga, produced placer accumulations (now paleoplacers) in the conglomerates of the uppermost formation of the Central Lapland greenstone belt. Placer deposits of controversial origin and provenance have also been worked for many years in the glaciofluvial sediments of northernmost Finland. The areas with greatest potential for the discovery of new orogenic gold deposits in Finland are the late Archean and Paleoproterozoic greenstone belts in eastern Finland and Lapland, respectively. Some Fe-Cu-Au skarns or epigenetic ironstone-hosted deposits have been mined in the past, and there may be potential for the discovery of larger iron oxide-copper-gold systems in the western Central Lapland greenstone belt. For intrusion-related (nonskarn) mineralization, the most promising areas are close to the Raahe-Ladoga Suture, and the potential for additional metamorphosed and deformed epithermal mineralization exists in the Tampere schist belt. The significant number of gold occurrences already known in these areas highlights the potential for new discoveries.

Atmospheric heavy metal deposition in Finland during 1985–2000 using mosses as bioindicators

Heavy metal deposition and changes in the deposition patterns were investigated on the basis of surveys carried out in 1985, 1990, 1995 and 2000. The concentrations of 10 elements (Cd, Cr, Cu, Fe, Ni, Pb, Zn and V; and As and Hg since 1995) were determined on moss ( Hylocomium splendens, Pleurozium schreberi) samples collected from the same permanent sample plots in each survey. The heavy metal concentrations, apart from those in southernmost Finland and close to a number of major emission sources, were relatively low. The mean concentrations of all the heavy metals decreased during the period covered by the surveys. The metals that showed the strongest decrease in concentration since 1985 were Pb (78%), V (70%) and Cd (67%). The concentrations of the other heavy metals decreased by 16–34%. The concentrations of Cr, Cu and Ni were clearly associated with local emission point sources and changes in emission levels. The concentrations of As and Hg, which were measured for the first time during the 1995 survey, decreased on the average by 26% and 10%, respectively.

Regional distribution of Chernobyl-derived plutonium deposition in Finland

The Chernobyl nuclear power plant accident in April 1986 caused a widely spread plume of radionuclides containing, amongst other materials, plutonium isotopes. The regional deposition of these nuclides in Finland has been assessed, based on samples of lichen, peat, precipitation, surface soil and grass. Unlike the deposition of transuranium elements from the weapons tests in the 1950"s and the 1960"s, the deposition in Finland from the Chernobyl accident was very unevenly distributed. Even then, the Chernobyl-derived deposition of 239,240Pu in the most contaminated regions of Finland was only around 10% of the global fallout from weapons tests. The total amount of 239,240Pu deposited in Finland was 1.1011 Bq (»25 g), i.e., approximately half of a percent of the activity deposited in the 1950"s and the 1960"s. In addition to the alpha-emitting Pu isotopes, the Chernobyl plume also contained a significant amount of the beta-emitting 241Pu, which is the precursor of the long-lived alpha-emitter 241Am. The highest plutonium deposition values were found in a relatively narrow swath from the southwestern coast of Finland northeastwards across the country. This is related to the calculated route of the air parcel trajectory associated with the initial explosion of the Chernobyl reactor. The high deposition values found in the northeastern part of the plume route over Finland can be attributed to the simultaneous occurrence of precipitation. The relatively high plutonium deposition in the southwestern part of Finland occurred, however, without concurrent precipitation. This indicates that the plutonium was at least partly associated with relatively large particles having a substantial deposition velocity due to gravitational setting

Fluorine in orthoamphibole dominated Zn-Cu-Pb deposits: examples from Finland and Australia

Abstract Volcanogenic massive sulphide (VMS) deposits commonly occur within much larger fluorine (F)-bearing hydrothermal systems, where cordierite-orthoamphibole rocks are characteristic pathfinder assemblages. Here we report whole-rock and mineral F contents for orthoamphibole bearing rocks and associated rock types from Zn-Cu-Pb deposits in Finland (Orijärvi, Iilijärvi, Pyhäsalmi, Mullikkoräme) and central Australia (Oonagalabi). Textural and mineralogical data suggest that F influx predates peak metamorphism in these deposits. The Mullikkoräme whole-rock data show positive correlations between F and X Mg = molar Mg/(Mg + Fe) and between F and elements of relatively low mobility (Ti, Al, Mg) and negative correlations between Fe and these elements. This suggests that iron was leached from silicate rocks by F-bearing fluids and was transferred to the Fe-rich sulphide ore. When normalized to immobile elements, F correlates positively with total metal content (Cu + Pb + Zn + Fe), consistent with the commonly observed increase of F content towards ore bodies. Combining all microprobe data, hydrous minerals show the following order of decreasing F/(F + OH) ratio when coexisting: apatite &gt; chondrodite &gt; biotite &gt; gedrite &gt; (hornblende, muscovite, anthophyllite) &gt; chlorite. The low- to medium-grade Finnish samples (Mullikkoräme: 500–560 °C at 1–3 kbar; Orijärvi: 550–650 °C at 3–5 kbar; Pyhäsalmi: 600–700 °C at 5–7 kbar) contain mainly F-poor anthophyllite, whereas F-rich gedrite is dominant in the higher grade Oonagalabi deposit (750–800 °C, 8–9 kbar). Temperature seems to have a significant, but X Mg a negligible influence on F partitioning between biotite and orthoamphiboles.