排序方式： 共有15条查询结果，搜索用时 46 毫秒
1.
Weathering of Hitura (W Finland) nickel sulphide mine tailings and release of heavy metals into pore water was studied with mineralogical (optical and electron microscopy, X-ray diffraction) and geochemical methods (selective extractions). Tailings were composed largely of serpentine, micas and amphiboles with only minor carbonates and sulphides. Sulphides, especially pyrrhotite, have oxidized intensively in the shallow tailings in 10–15 years, but a majority of the tailings have remained unchanged. Oxidation has resulted in depletion of carbonates, slightly decreased pH, and heavy metal (Ni, Zn) release in pore water as well as in the precipitation of secondary Fe precipitates. Nevertheless, in the middle of the tailings area, where the oxidation front moves primarily downward, released heavy metals have been adsorbed and immobilized with these precipitates deeper in the oxidation zone. In contrast to what was seen in pore water pH, but in accordance with static tests of the previous studies, the neutralisation potential ratio (NPR) calculated based on the mineralogical composition and the total sulphur content suggested that tailings are ‘not potentially acid mine drainage (AMD) generating’. However, the calculated buffering capacity of the tailings resulted largely from the abundant serpentine because of the low carbonate content. Despite its slow weathering rate, serpentine may buffer the acidity to some extent through ion exchange processes in fine ground tailings. Nevertheless, in practice, acid production capacity of the tailings depends primarily on the balance between Ca–Mg carbonates and iron sulphides. NPR calculation based on carbonate and sulphur contents suggested, that the Hitura tailings are ‘likely AMD generating’. The study shows that sulphide oxidation can be significant in mobilisation of heavy metals even in apparently non-acid producing, low sulphide tailings. Therefore, prevention of oxygen diffusion into tailings is also essential in this type of sulphide tailings. 相似文献
2.
Use of biliary PAH metabolites as a biomarker of pollution in fish from the Baltic Sea 总被引：2，自引：0，他引：2
Vuorinen PJ Keinänen M Vuontisjärvi H Barsiene J Broeg K Förlin L Gercken J Kopecka J Köhler A Parkkonen J Pempkowiak J Schiedek D 《Marine pollution bulletin》2006,53(8-9):479-487
During field campaigns of the BEEP project (Biological Effects of Environmental Pollution in Marine Coastal Ecosystems) in 2001-2002, metabolites of polycyclic aromatic hydrocarbons (PAHs) were determined in bile samples from three fish species, flounder (Platichthys flesus), perch (Perca fluviatilis) and eelpout (Zoarces viviparus), from four separate areas in the Baltic Sea. Two determination methods were applied: fixed wavelength fluorescence (FF) for pyrene-type metabolites and high-performance liquid chromatography with fluorescence detection (HPLC). There was a good correlation between the FF method and 1-OH pyrene determined by HPLC. Normalisation of the FF data for absorbance at 380 nm or bile protein concentrations greatly increased variance in one third and decreased it in two thirds of the cases and resulted in a loss of significant differences (protein normalisation) between the sampling stations, but normalisation of the HPLC data had little effect on the results. The biliary PAH metabolite content was usually higher in males than in females. In perch and eelpout the biliary PAH contents were at similar levels, whereas in flounder the levels were lower. The sampling areas arranged in decreasing order of biliary PAH contents were: Wismar Bay > Gulf of Gdansk > Lithuanian coast > Kvadofj?rden (reference area). It is concluded that FF with un-normalised data is a reliable and simple method for monitoring purposes and only one sex of a selected species should be used. 相似文献
3.
Redistribution of potentially harmful metals and As was studied based on selective extractions in two active sulphide mine tailings impoundments in Finland. The Hitura tailings area contains residue from Ni ore processing, while the Luikonlahti site includes tailings from the processing of Cu–Co–Zn–Ni and talc ores. To characterize the element solid-phase speciation with respect to sulphide oxidation intensity and the water saturation level of the tailings, drill cores were collected from border zones and mid-impoundment locations. The mobility and solid-phase fractionation of Ni, Cu, Co, Zn, Cr, Fe, Ca, Al, As, and S were analysed using a 5-step non-sequential (parallel) selective extraction procedure. The results indicated that metal redistribution and sulphide oxidation intensity were largely controlled by the disposal history and strategy of the tailings (sorting, exposure of sulphides due to delayed burial), impoundment structure and water table, and reactivity of the tailings. Metal redistribution suggested sulphide weathering in the tailings surface, but also in unsaturated proximal areas beside the earthen dams, and in water-saturated bottom layers, where O2-rich infiltration is possible. Sulphide oxidation released trace metals from sulphide minerals at both locations. In the Hitura tailings, with sufficient buffering capacity, pH remained neutral and the mobilized metals were retained by secondary Fe precipitates deeper in the oxidized zone. In contrast, sulphide oxidation-induced acidity and rise in the water table after oxidation apparently remobilized the previously retained metals in Luikonlahti. In general, continuous disposal of tailings decreased the sulphide oxidation intensity in active tailings, unless there was a delay in burial and the reactive tailings were unsaturated after deposition. 相似文献
4.
Raimo Sutinen Paavo NÄrhi Maarit Middleton Pekka HÄnninen Mauri Timonen Marja‐Liisa Sutinen 《Boreas: An International Journal of Quaternary Research》2012,41(3):367-378
As a result of global changes, shifts of alpine tree lines towards higher elevations have been recorded, but the role of the spatial variability of the snowpack and zonal‐pattern soil‐nutrient regimes is poorly understood. Norway spruce (Picea abies (L.) Karst) is best suited to fertile soils, and hence we applied soil physical‐chemical and snow measurements and the age chronology of Norway spruce along an elevational gradient (380–557 m a.s.l.) to address a vertical soil zonality hypothesis on mafic Lommoltunturi fell in Finnish Lapland. With regard to increasing elevation, we found an increase in soil NTOT, CTOT and Al, but a decrease in soil Ca, Mg and Ca:Al ratio as well as in electrical conductivity (EC). In addition, the snowpack was significantly thicker in low‐elevation forest than in the tree line and open tundra. In the 1840s, spruce established on low‐elevation soils with a Ca:Al ratio of 2.2. Starting from the 1920s a significant shift of spruce occurred such that it took 60 years to expand the tree line by 55 m in elevation. The spruce tree line has advanced, and the age distribution indicates new colonization of spruce in closed forest up to tundra. The poor soil Ca:Al ratio of 0.02 on tundra apparently is a constraint for spruce. Spruce forest is young (<165 years), and hence we argue that spruce has expanded onto formerly tree‐free sites of this mafic fell. This paper demonstrates that vertical soil zonality is a potential driver for the diffuse tree line of Picea abies on mafic Fennoscandian fells. 相似文献
5.
Timo Tiira Marja Uski Jari Kortström Outi Kaisko Annakaisa Korja 《Journal of Seismology》2016,20(2):397-417
This study presents a plan for seismic monitoring of a region around a potential nuclear power plant. Seismic monitoring is needed to evaluate seismic risk. The International Atomic Energy Agency has set guidelines on seismic hazard evaluation and monitoring of such areas. According to these guidelines, we have made a plan for a local network of seismic stations to collect data for seismic source characterization and seismotectonic interpretations, as well as to monitor seismic activity and natural hazards. The detection and location capability of the network were simulated using different station configurations by computing spatial azimuthal coverages and detection threshold magnitudes. Background noise conditions around Pyhäjoki were analyzed by comparing data from different stations. The annual number of microearthquakes that should be detected with a dense local network centered around Pyhäjoki was estimated. The network should be dense enough to fulfill the requirements of azimuthal coverage better than 180° and automatic event location capability down to ML?～?0 within a distance of 25 km from the site. A network of 10 stations should be enough to reach these goals. With this setup, the detection threshold magnitudes are estimated to be ML?=??0.1 and ML?=?0.1 within a radius of 25 and 50 km from Pyhäjoki, respectively. The annual number of earthquakes detected by the network is estimated to be 2 (ML?≥?～ ?0.1) within 25 km radius and 5 (ML?≥?～?0.1 to ～0.1) within 50 km radius. The location accuracy within 25 km radius is estimated to be 1–2 and 4 km for horizontal coordinates and depth, respectively. Thus, the network is dense enough to map out capable faults with horizontal accuracy of 1–2 km within 25 km radius of the site. The estimation is based on the location accuracies of five existing networks in northern Europe. Local factors, such as seismic noise sources, geology and infrastructure might limit the station configuration and detection and location capability of the network. 相似文献
6.
David Read Stuart Black Tracy Buckby Karl-Heinz Hellmuth Nuria Marcos Marja Siitari-Kauppi 《Global and Planetary Change》2008,60(3-4):235-249
Uranium series dating has been carried out on secondary uranyl silicate minerals formed during sub-glacial and post-glacial weathering of Proterozoic uraninite ores in south west Finland. The samples were obtained from two sites adjacent to the Salpauselkä III ice marginal formation and cover a range of depths, from the surface to more than 60 m. Measured ages fall into three distinct groups, 70–100 ka, 28–36 ka and < 2500 yr. The youngest set is associated with surface exposures and the crystals display clear evidence of re-working. The most likely trigger for uranium release at depths below the surface weathering zone is intrusion of oxidising glacial melt water. The latter is often characterised by very high discharge rates along channels, which close once the overpressure generated at the ice margin is released. There is excellent correspondence between the two Finnish sites and published data for similar deposits over a large area of southern and central Sweden. None of the seventy samples analysed gave a U–Th age between 40 and 70 ka; a second hiatus is apparent at 20 ka, coinciding with the Last Glacial Maximum. Thus, the process responsible for uranyl silicate formation was halted for significant periods, owing to a change in geochemical conditions or the hydrogeological regime. These data support the presence of interstadial conditions during the Early and Middle Weichselian since in the absence of major climatic perturbations the uranium phases at depth are stable. When viewed in conjunction with proxy data from mammoth remains it would appear that the region was ice-free prior to the Last Glacial Maximum. 相似文献
7.
During May 2003 a swarm of 16 earthquakes (ML = 0.6–2.1) occurred at Anjalankoski, south-eastern Finland. The activity lasted for three weeks, but additional two events were observed at the same location in October 2004. A comparison of the waveforms indicated that the source mechanisms and the hypocentres of the events were nearly identical.A relative earthquake location method was applied to better define the geometry of the cluster and to identify the fault plane associated with the earthquakes. The relocated earthquakes aligned along an ENE–WSW trending zone, with a lateral extent of about 1.0 km by 0.8 km. The relative location and the waveform-modelling of depth sensitive surface wave (Rg) and S-to-P converted body wave (sP) phases indicated that the events were unusually shallow, most likely occurring within the first 2 km of the surface. The revised historical earthquake data confirm that shallow swarm-type seismicity is characteristic to the area.The focal mechanism obtained as a composite solution of the five strongest events corresponds to dip-slip motion along a nearly vertical fault plane (strike = 250°, dip = 80°, rake = 90°). The dip and strike of this nodal plane as well as the relocated hypocentres coincide with an internal intrusion boundary of the Vyborg rapakivi batholith.The events occur under a compressive local stress field, which is explained by large gravitational potential energy differences and ridge-push forces. Pore-pressure changes caused by intrusion of ground water and/or radon gas into the fracture zones are suggested to govern the swarm-type earthquake activity. 相似文献
8.
9.
Focal mechanisms for three recent earthquakes in Finland are determined using P-wave polarities together with SV/P and SH/P phase amplitude ratios. The events occurred on May 11, 2000 in Toivakka, Central Finland (ML=2.4), on September 15, 2000 in Kuusamo, northeastern Finland (ML=3.5), and on May 2, 2001 in Kolari, western Finnish Lapland (ML=2.9).In order to obtain reliable estimates of the source parameters, one-dimensional crust and upper mantle velocity models are derived for the epicenter areas from deep-seismic sounding results. The starting models are modified by one-dimensional ray tracing using the earthquake observations. The events are relocated by employing P- and S-phase arrival times from the nearest seismic stations and the final velocity models. Synthetic waveforms, calculated with the reflectivity method, are used to further constrain and verify the source and structural parameters.The Toivakka earthquake indicates thrust- or reverse-faulting mechanism at a depth of 5 km. After comparison with aeromagnetic and topographic data we suggest the eastward dipping nodal plane (358°/42°) was the fault plane. The best-fitting fault plane solution of the Kolari earthquake suggests pure thrust-faulting at a depth of 5 km. The nodal plane striking 035°/30° correlates well with surface observations of the postglacial, possibly listric fault systems in the source area. The Kuusamo earthquake (focal depth 14 km) has a normal-faulting mechanism with the nodal planes trending 133°/47° or 284°/47°. Preference is given to the SW-dipping nodal plane, as it seems to coincide with topographic and magnetic lineament directions that have been active after the last ice age.The three earthquakes have occurred in old Precambrian faults and shear zones, which have been reactivated. The reactivated faults are favourably oriented in the local stress field. 相似文献
10.
Toni Roiha Marja Tiirola Matteo Cazzanelli Milla Rautio 《Aquatic Sciences - Research Across Boundaries》2012,74(3):513-525
Bacterial communities in 16 oligotrophic ponds in Kilpisj?rvi, subarctic Finland, were studied to test the hypothesis that dissolved organic carbon (DOC) quantity and quality differently influence bacterioplankton. The ponds were located below and above treeline at 600?m a.s.l., with 2?C4 fold higher concentration of DOC below treeline. The concentration of DOC changed during the open-water season with highest values measured in mid-summer. Bacterial production, abundance, biomass were highest in mid-summer and correlated positively with the concentration of DOC. Quality indices of DOC showed that spring differed from the rest of the season. Highest specific UV-absorbance (SUVA) and humification index (HI), ratio a250/a265 and lowest fluorescence index (FI) were found during spring compared to summer and autumn, possibly indicating higher relative importance of allochthonous carbon during spring and a seasonal effect of photo-oxidation. According to Length Heterogeneity Polymerase Chain Reaction (LH-PCR) analyses, bacterial communities in spring were significantly different from those later in the season, possible due to the introduction of terrestrial bacteria associated with higher molecular weight material in spring DOC. Comparison between ponds situated above and below treeline revealed that bacteria were more abundant and productive at lower altitudes, which is probably connected to higher concentrations of DOC. The results also suggest that increased temperature and precipitation induced by global change and consequent higher allochthonous DOC runoff from the catchment could have a strong impact on biomass, productivity and community composition of micro-organisms in subarctic ponds and lakes. 相似文献