| 1. |
- Paulsson, Oscar, et al.
(författare)
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Algal nutrient limitation and metal uptake experiment in the Åkerberg pit lake, northern Sweden
- 2021
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 125
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Tidskriftsartikel (refereegranskat)abstract
- A microcosm nutrient limitation experiment was conducted in the Åkerberg pit lake, located in Västerbotten, northern Sweden, in the summer of 2018. The microcosms were fertilized with N, P and N and P in combination. Chlorophyll-a concentrations were used to estimate algal growth. Filtered and suspended metal concentrations of the microcosms were compared to see if an increase in algal growth would lead to higher metal uptake. The results show that the microcosms fertilized with N and P had the highest chlorophyll-a concentrations (3–3.4 μg/l). This corresponds to an increase of 9.5–11 times compared to the initial chlorophyll-a concentrations, suggesting that the lake is nutrient poor with regards to both N and P. An increase of the metal concentration in the suspended particulate samples (>0.2 μm) of the microcosms fertilized with both N and P could be observed particularly for the mining-related metals Cd, Co, Ni, and Zn. The uptake of these metals amounted to 2.5–20% (Cd), 2.6–14% (Co), 0.87–1.8% (Ni), and 19–64% (Zn) of their filtered concentrations (<0.2 μm).
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| 2. |
- Paulsson, Oscar, et al.
(författare)
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Diel variations in dissolved oxygen concentration and algal growth in the Laver pit lake, northern Sweden
- 2023
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Ingår i: Applied Geochemistry. - : Elsevier Ltd. - 0883-2927 .- 1872-9134. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- The diel oxygen technique relying on automated in-situ measurements of dissolved oxygen was used as an indicator of seasonal and diurnal variations of photosynthesis in the circumneutral Laver pit lake in northern Sweden. From July to September 2017, surface water temperature, electrical conductivity, pH, and dissolved oxygen were continuously measured at a time resolution of 30 min using sensors mounted on a floating buoy. The data could be monitored in real-time using a browser-based software and permitted calculation of gross primary production (GPP), net ecosystem production (NEP), and respiration (R) in the lake. The dissolved O2 concentration showed a consistent pattern of diel variations that reached up to 0.5 mg L−1 during the warmer summer period (July–August). Towards the end of August these variations decreased in magnitude and remained at ∼0.1 mg L−1 throughout September. pH showed diel variations that mimicked those of dissolved O2, with maximum daily variations of 0.4–0.5 pH units during July and August. A seven-day moving average of GPP showed a peak during July to mid-August, and the maximum GPP value of 0.55 mg O2 L−1 day−1 is similar to those found in natural oligotrophic lakes. A phytoplankton sample showed a total biomass concentration of 24 μg L−1, with the species Chrysophyceae, Chlorophyta, and Bacillariophyta occurring in the water. Diel oxygen data indicated that respiration by autotrophs and respiration of autochthonous labile organic matter by heterotrophs dominated in the lake, as is often the case in lakes where planktonic primary production is the main supplier of labile organic carbon. A close coupling between R and GPP suggests that nearly all GPP was respired in the epilimnion. The study shows that the diel oxygen technique can be used for real-time monitoring of seasonal and diurnal variations of dissolved oxygen and pH in pit lakes. This would be a useful technique in pit lake remediation projects where fertilization is used to stimulate algal growth and metal sequestering by algae.
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| 3. |
- Paulsson, Oscar, et al.
(författare)
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Modelled impact of climate change scenarios on hydrodynamics and water quality of the Rävlidmyran pit lake, northern Sweden
- 2022
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 139
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Tidskriftsartikel (refereegranskat)abstract
- Predictive modelling for three climate scenarios, based on the three greenhouse gas emission scenarios RCP 2.6, RCP 4.5 and RCP 8.5, was conducted for the Rävlidmyran pit lake, located in Västerbotten, northern Sweden. The model output for pH, temperature, dissolved oxygen, Cl, Fe3+, and Zn during the 10-year period 2090–2099 was compared to the model output during the 10-year period 2006–2015, for which measured meteorological data was used as input. Changes in thermocline, chemocline and water outflow were also evaluated. The results indicate that the water outflow from the pit lake will increase, as well as the number of days when the temperature in the mixolimnion exceeds 12 °C. The largest changes are seen for the highest greenhouse gas emission scenario (RCP 8.5). A small increase in Zn outflow (4.4%) could be observed for the RCP 8.5 emission scenario compared to the RCP 2.6 scenario. The results also indicate that the stratification of the lake is relatively stable, and it is predicted to remain meromictic for all climate scenarios. However, a sensitivity analysis indicates that a reduction of groundwater inflow element concentrations by 25–50% may result in a weakened stratification of the lake. Minor dilution could be observed in the monimolimnion of the lake as the modelled Cl concentration decreased by ∼0.3 mg/L in the RCP 8.5 emission scenario compared to the 2006–2015 period. The Cl concentration was also lower in the RCP 8.5 scenario compared to the RCP 2.6 and RCP 4.5 scenario, both in the mixolimnion and the monimolimnion.
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| 4. |
- Paulsson, Oscar, et al.
(författare)
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Pit lake oxygen and hydrogen isotopic composition in subarctic Sweden : A comparison to the local meteoric water line
- 2020
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 118
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Tidskriftsartikel (refereegranskat)abstract
- A local meteoric water line based on rainwater and snow core samples was developed for an area comprising parts of eastern Norrbotten and Västerbotten in northern Sweden. The oxygen and hydrogen isotopic composition of groundwater and water from four pit lakes was compared to the local meteoric water line by line-conditioned excess. The isotopic mass balance method was used to estimate the evaporation over inflow ratio and the residence time of the lakes. The results show that the local meteoric water line for the study area is: δ2H = (7.80 ± 0.09) δ18O + (4.35 ± 1.35) ‰, which is close to the global meteoric water line. The surface water of the four pit lakes all have negative line-conditioned excess values which indicate that they have been affected by evaporation. The groundwater plots on the local meteoric water line making it hard to utilize in a mixing model for a lake where precipitation and groundwater are treated as two different sources. Two scenarios were used to estimate the starting composition of the lakes for the isotopic mass balance method. One was based on the intersection point of the local meteoric water line and the local evaporation line and gave evaporation over inflow ratios ranging from 0.23 to 0.74 and residence times ranging from 7.2 to 44.9 years. The second scenario was based on the weighted average composition of precipitation and gave evaporation over inflow ratios ranging from 0.07 to 0.32 and residence times ranging from 2.8 to 14.9 years.
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| 5. |
- Paulsson, Oscar
(författare)
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Pit lake water quality and hydrology : Insights from case studies and modelling of pit lakes in northern Sweden
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As extraction techniques are improving an increased number of low grade deposits can be economically mined. However, this also means that the number of open pit mines will increase and as a result the number of pit lakes as well. This is of environmental concern as the pit lakes, depending on the geology and other factors, potentially can have a negative impact on surrounding ecosystems, e.g. through high metal concentrations, low pH, and by affecting the hydrologic system. Sweden has a long history of mining and is one the largest metal suppliers in Europe, and many of the mines are located in the northern part of the country. The project aim was to better understand and be able to predict pit lake water quality and some of the underlying processes affecting it, with a focus on cold climates, where temperatures are low and the lakes are ice covered for prolonged periods of time. The following field measurements were conducted in the Laver and Åkerberg pit lakes: 1) minewall stations measuring metal leaching rates from pit walls, 2) oxygen and hydrogen isotopic composition of precipitation and pit lakes to better understand pit lake hydrology (including also the Udden and Rävlidmyran pit lakes), 3) a nutrient limitation and metal uptake experiment in the Åkerberg pit lake, and 4) a continuously measuring buoy installed in the Laver pit lake where short term fluctuations in water quality parameters could be observed. A bathymetric map of the Åkerberg pit lake was also generated during the project. Additionally, modelling of the Rävlidmyran pit lake was conducted based on three different climate scenarios. Measurements of water quality parameters showed that both the Laver and Åkerberg pit lakes have relatively good water quality, pH 6.1–7.4, specific conductivity 41–352 μS/cm and pH 7.6-7.7, specific conductivity 137–140 μS/cm, respectively, and low concentrations of metals. Algal growth was successfully stimulated in microcosms in the Åkerberg pit lake, through addition of the nutrients N and P in combination. Chlorophyll-a concentrations, which were used to estimate algal growth, were 9.5-11 times higher than at the beginning of the experiment in these microcosms. It was also seen that the metal concentration in the suspended particulate phase increased, suggesting that metals were taken up by algae. In the Laver pit lake measurements from the continuously measuring buoy showed diurnal variations for pH, dissolved oxygen, and temperature. The pH and dissolved oxygen was increasing during daytime, indicating that algal growth was increasing. A local meteoric water line, which can be used to separate sources of water from precipitation, if their isotopic compositions are different, was constructed for the study area (δ2H = (7.80 ± 0.09) δ18O + (4.35 ± 1.35) ‰). It was seen that the groundwater had a similar stable isotopic composition as precipitation, as its composition fell on the local meteoric water line. It was also seen that the studied pit lakes had undergone evaporation as they plotted on a local evaporation line (δ2H = (6.88 ± 0.47) δ18O + (−12.75 ± 5.60) ‰). Residence times were calculated for the pit lakes, ranging from 2.9-44.9 years, using the isotopic mass balance method. Modelling of the Rävlidmyran pit lake suggests that it is fairly stable and will remain meromictic during a modelled 100 year period. No major differences in redox or oxygen levels were observed. The temperature is predicted to increase in the mixolimnion along with a slight decrease in dissolved oxygen concentration. The modelling also indicates that the water outflow from the lake might increase, and as a consequence, a slight increase of metal outflow was observed as well. Based on minewall stations, installed at the Laver and Åkerberg mine sites, leaching rates (µg/m2/week) of metals were estimated. These were used to approximate the total contribution of metals from the pit walls to the pit lakes over the course of a year. A difference in metal leaching could be observed for the two mine sites which could be attributed to the deposit type.
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| 6. |
- Paulsson, Oscar, et al.
(författare)
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Stimulating algal growth through wood ash fertilization in the Åkerberg pit lake, northern Sweden
- 2023
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Ingår i: Applied Geochemistry. - : Elsevier Ltd. - 0883-2927 .- 1872-9134. ; 151
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Tidskriftsartikel (refereegranskat)abstract
- Fifteen microcosms were installed in the Åkerberg pit lake for 15 days in the summer season (July) 2021. To stimulate algal growth, the microcosms were fertilized with two P-rich wood ashes, and KNO3. Chlorophyll-a was used as an indicator of algal growth while filtered (<0.2 μm) and particulate suspended element concentrations (>0.2 μm) were used to estimate algal metal uptake. Water quality measurements and water sampling were conducted on three occasions (every five days) and at the start of the experiment to monitor algal growth. The chlorophyll-a concentration in the microcosms fertilized with wood ash increased from 0.3-0.8 μg/L at the start of the experiment to 53–77 μg/L after 15 days. Algal element uptake of filtered concentrations (<0.2 μm) was observed for many elements including, Ni (33–36%), Zn (22–65%) and Cd (22–54%). This suggests that wood ash could be used to stimulate algal growth in pit lakes by acting as a source for P and potentially also other nutrients. The highest chlorophyll-a concentrations were seen on day 10, indicating that a breakdown of chlorophyll-a impacted the measured concentrations, which otherwise could have been higher.
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| 7. |
- Pontér, Simon, et al.
(författare)
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Early diagenesis of uranium in lakes receiving deep groundwater from the Kiruna mine, northern Sweden
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 793
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Tidskriftsartikel (refereegranskat)abstract
- The uranium (U) concentrations and isotopic composition of waters and sediment cores were used to investigate the transport and accumulation of U in a water system (tailings pond, two lakes, and the Kalix River) receiving mine waters from the Kiruna mine. Concentrations of dissolved U decrease two orders of magnitude between the inflow of mine waters and in the Kalix River, while the concentration of the element bound to particulate matter increases, most likely due to sorption on iron‑manganese hydroxides and organic matter. The vertical distribution of U in the water column differs between two polluted lakes with a potential indication of dissolved U supply from sediment's pore waters at anoxic conditions. Since the beginning of exposure in the 1950s, U concentrations in lake sediments have increased >20-fold, reaching concentrations above 50 μg g-1. The distribution of anthropogenic U between the lakes does not follow the distribution of other mine water contaminants, with a higher relative proportion of U accumulating in the sediments of the second lake.Concentrations of redox-sensitive elements in the sediment core as well as Fe isotopic composition were used to re-construct past redox-conditions potentially controlling early diagenesis of U in surface sediments. Two analytical techniques (ICP-SFMS and MC-ICP-MS) were used for the determination of U isotopic composition, providing an extra dimension in the understanding of processes in the system. The (234 U)/(238 U) activity ratio (AR) is rather uniform in the tailings pond but varies considerably in water and lake sediments providing a potential tracer for U transport from the Kiruna mine through the water system, and U immobilization in sediments. The U mass balance in the Rakkurijoki system as well as the amount of anthropogenic U accumulated in lake sediments were evaluated, indicating the immobilization in the two lakes of 170 kg and 285 kg U, respectively.
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| 8. |
- Pontér, Simon, et al.
(författare)
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Evaluation of a Multi-Isotope Approach as a Complement to Concentration Data within Environmental Forensics
- 2021
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Ingår i: Minerals. - : MDPI. - 2075-163X. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Heavy metal contamination was identified in groundwater monitoring wells surrounding a waste deposit facility at the Rönnskär Cu–Pb–Zn smelter in Skellefteå, Northern Sweden, as well as in brackish water and sediments from the nearby harbor. Following an investigative study of the surrounding area, brackish water from the Baltic Sea and sediments from a nearby harbor were also determined to be contaminated. This study investigated the ranges of isotopic compositions of four elements (Cd, Cu, Pb, and Zn) in smelter materials (ores, products, and waste) and polluted groundwater sediments of the affected area. The study’s objective was to evaluate the variability of the polluting source and identify possible isotope fractionation. This study further assesses the viability of using isotopic information to identify the source of the pollutant. These data were used in combination with multi-element screening analysis and multivariate statistical techniques. Expanding the number of elements utilized in isotope tracing empowers our abilities to decipher the source(s) and the extent of environmental exposure from contamination events related to mining and refining operations.
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| 9. |
- Pontér, Simon
(författare)
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Isotope Ratio and Trace Element Measurements Using Inductively Coupled Plasma – Mass Spectrometry : Method Development and Applications in Environmental Forensics
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental Forensics is a scientific methodology developed for identifying sources, the timing of release, and transport pathways for potentially hazardous environmental contaminants. It combines a variety of analytical methods with principles derived from disciplines such as chemistry, geology, geochemistry, hydrogeology, and statistics, with the purpose to provide objective scientific and legal conclusions on the source and/or time of a contaminant release. Instrumental development and refining separation schemes have allowed higher quality data to be obtained and played a major role in the recent progress of the field. The use of modern techniques such as inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for trace and ultra-trace element concentrations and isotope ratio measurements provides Environmental Forensics with new opportunities. The work described in the present thesis has been focused on closing knowledge gaps in the field of Environmental Forensics, including analytical method development as well as processes- and source(s)t-tracing using multiple isotopes in environmental studies. Paper I is dedicated to the assessment of performance of double-focusing, sector field mass spectrometry (ICP-SFMS) for determination of analytes (including technology critical elements (TCE)) at ultra-trace levels in complex matrixes, with a special emphasis on the determination of Au, Ag, Ir, Os, Pd, Pt, Re, Rh, Ru, Sb, and Te. Instrumentation development was performed by optimization and testing different configurations of the ICP-SFMS introduction system as well as various sample preparations, pre-concentration, and matrix separation methods. Factors affecting instrumental sensitivity, contamination risks, reagent purity, spectral interferences, matrix effects, and analyte recovery are discussed. Optimized matrix specific methods were applied to a range of reference and control materials (riverine and brackish waters, seawater, whole blood, serum, and urine). Samples included brackish water and seawater from the Laptev Sea, venous blood, tap water, and snow samples collected in Luleå, northern Sweden. In Paper II an analytical procedure was developed, consisting of high pressure/temperature acid digestion using an UltraCLAVE system followed by a one pass, single column matrix separation allowing the first Cr isotope study in epiphytic lichens and mosses, as well as analysis of chromite and soils by ICP-SFMS and MC-ICP-MS. The overall reproducibility of the method, which was found to be ±0.11‰ (2σ), was assessed by replicate preparation and Cr isotope ratio measurements performed by different operators in multiple analytical sessions over a few months. Results indicated no correlation between soil concentrations and isotopic compositions (R2=0.2), while a strong negative correlation (R2=0.7) between Cr concentrations in lichens and mosses and δ53Cr signatures indicates airborne Cr contribution from local anthropogenic source(s) depleted in heavy isotopes. Chromium isotope data obtained for lichens and mosses indicate the potential of using this approach for tracing and quantifying airborne Cr pollution caused by stainless steel foundries. Paper III evaluates heavy metal contamination in brackish water, groundwater, and sediments collected close to a deposit facility at the Rönnskär Cu–Pb–Zn smelter in Skellefteå, northern Sweden. This study investigates the ranges of isotopic compositions of four elements (Cd, Cu, Pb, and Zn) in smelter process materials (ores, products, and waste), as well as in polluted groundwater and sediments of the affected area. The study’s objective was to evaluate the isotope variability of the polluting source and identify possible isotope fractionation between a source and a sink. This study further assesses the viability of using isotopic information to identify the source of the pollutant in various matrices. Isotope composition data were used as a compliment to multi-element screening analysis and multivariate statistical techniques. Expanding the number of elements utilized in isotope tracing empowers our abilities to decipher the source(s) and the extent of environmental exposure from contamination events related to mining and refining operations. Results show clusters of elements with elevated concentrations and significant inter-element correlations that can be traced practically in all matrices tested (from dust samples to sediments), confirming a link between the source and the polluted environmental compartments. Differences in the relative mobility in the environment for different elements (shown in the example of Re and Mo distribution in sediments) may however affect the usefulness of the elemental ratios in reconstructing the extent and timing of pollution events. Among the isotopes evaluated in this study, radiogenic Pb and stable Zn isotope systems offer the most promising source identification in the area close to the smelter. However, temporal variability in the isotopic composition of the source adds complexity for the Pb isotopes. Numerous post-deposition fractionating processes alter the original source ratios for Cu, Zn, and to a lesser extent, Cd. At larger distances from the source, additional fractionation during element migration and dilution of source-specific signatures with background components makes source tracing more challenging. To fully realize the great promise offered by expanding the number of elements utilized in isotope tracing as a powerful way to decipher sources and fate of environmental exposure, a comprehensive evaluation of both source(s) and background variability, as well as post-depositional fractionation, needs to be an integral part of any Environmental Forensics investigation. Paper IV combines uranium (U) and other trace element concentrations with iron and uranium isotope measurements as a proxy to reconstruct historical changes of U release and accumulation in one tailings pond and two lakes (Mettä-Rakkurijärvi and Rakkurijärvi) receiving deep mine waters in northern Sweden, Kiruna. Uranium is deposited in lake sediments downstream of the mine, with elevated U concentrations in the surface sediments exceeding 55 mg kg-1, a >20-fold increase from the pre-industrial years. The distribution of anthropogenic U between the lakes does not follow the distribution of other contaminants reaching the system with mine waters, with a higher relative proportion of U accumulating in sediments of the second lake. Vertical concentration profiles for redox-sensitive elements as well as Fe isotopic composition were used to re-construct past redox-conditions potentially controlling early diagenesis of U in surface sediments. The isotopic signature of U in surface sediments (activity ratio AR=2.5) is far from that of secular equilibrium. These signatures are a function of time and weathering-induced fractionation, used here as a source signature of U originating in the deep groundwater in the mine. Linear regressions of inverse U concentration in water (dissolved, particulate, and total) versus AR reaffirms a simplified mixing situation with two isotopically distinct sources: 1) a natural source (low U concentration, AR 2.64), and 2) an anthropogenic source (high U concentration, AR ≈1.95). After mixing with mine water from the Rakkurijoki system, the AR of receiving Kalix River water decreases from 2.66 to 2.24. Monitoring data on the surface waters demonstrate the effects of the tributary waters of the Rakkurijoki systems as it discharges into the Kalix River, where the U concentration of the river downstream is more than doubled.
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| 10. |
- Sutliff-Johansson, Stacy, et al.
(författare)
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Groundwater environmental forensic investigation combining multivariate statistical techniques and screening analyses
- 2020
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Ingår i: Environmental Forensics. - : Taylor & Francis. - 1527-5922 .- 1527-5930.
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Tidskriftsartikel (refereegranskat)abstract
- Heavy metal contamination was identified in groundwater monitoring wells surrounding a waste deposit facility at the Rönnskär Cu–Pb–Zn smelter in Skellefteå, northern Sweden. The main objective of this study is to identify the sources of contamination, utilizing element screening analyses and multivariate statistical techniques. A second objective is to determine the usefulness of these techniques in Environmental Forensics investigations of contaminated groundwater at a complex industrial site. Water samples were collected from four groundwater monitoring wells and six waste deposit cells surrounding the contaminated area. Seventy-two elements are statistically examined and the dataset is reduced to the variables representative of the contaminated source material from the smelting process. A three-component model is identified and explains 88% of the total variation in the dataset. Component 1 includes concentrations of Cd, Co, Ni, Rb, Re, and Zn. This component displays a high correlation with two of the deposit cells and their associated groundwater monitoring wells. Component 2 is comprised of Sb, Cu, and Mo. This component displays a correlation between all monitoring wells and deposits likely due to the high mobility of these elements as oxyanions. Component 3 is dominated by As and displays high correlation to three older deposit cells representing a completely different source than for Components 1 and 2. The application of screening analyses and multivariate statistics in this study has achieved a meaningful identification of sources of contamination in the investigated area. It was also shown to be useful as an initial survey aiming to optimize a full-scale monitoring program at the site.
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| 11. |
- Sutliff-Johansson, Stacy, et al.
(författare)
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Tracing anthropogenic sources of Tantalum and Niobium in Bothnian Bay sediments, Sweden
- 2021
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Ingår i: Journal of Soils and Sediments. - : Springer. - 1439-0108 .- 1614-7480. ; 21:3, s. 1488-1503
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Tidskriftsartikel (refereegranskat)abstract
- Purpose This study aims to evaluate temporal trends of Tantalum (Ta) and Niobium (Nb) concentrations in northern Baltic Sea sediments with focus on the potential impact from the Ronnskar sulfide ore smelter, located 15 km east of Skelleftea in northern Sweden. The potential of Ta or Nb to serve as tracers for environmental pollution caused by the electronic waste is compared. Lastly, correlations between Ta and Nb concentrations and those of major redox elements are investigated. Methods A 35-cm-deep core was collected in the harbor bay (Kallholmsfjarden) outside of the smelter. A secondary 6-m-deep sediment core was collected in the deep Bothnian Bay for comparative purposes. Element screening analysis was conducted the using ICP-SFMS for the Kallhomsfjarden core and a combination of ICP-SFMS and ICP-OES for the Bothnian Bay core. In the final analysis, a 5-step sequential extraction technique was preformed to allow for better prediction of the fate and mobility of Ta and Nb. Results and discussion In the vicinity of the smelter, Ta concentration increases from 0.42 to 3.8 ppm from the time coinciding with the beginning of electronic waste processing. Conversely, Nb concentration remained stable at background levels throughout the core at 6.33 +/- 0.78 ppm. The Nb/Ta ratio thus changed from 14.5 to 1.7, reflecting an increase of anthropogenic input of Ta into the bay sediments. In the pre-industrial part of the sediment, concentrations of both elements follow concentration of aluminosilicates in the core. In recent sediments, however, the anthropogenic Ta exhibits an association with hydrous ferric oxides (HFOs) and organic matter. Conclusions Notable increases in Ta concentrations began following the beginning of scrap metal and electronic waste processing at the Ronnskar smelter. Anthropogenic Ta introduced in the upper portion of the sediment and are more associated with HFOs and organic material than natural Ta seen in the deeper parts of the core where detrital Ta is most common. Niobium was not affected by the Ronnskar smelter and displayed no notable change to the preindustrial background.
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| 12. |
- Sutliff-Johansson, Stacy
(författare)
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Tracing anthropogenic Technology Critical Elements using Environmental Forensics : Case studies at Kallholmsfjärden and the Bothnian Bay, northern Sweden
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The rapidly changing landscape of today's technology industry has increased the number of electronic products being discarded. Society is always on the hunt for the latest product and newest technological advancement, thereby creating a constant influx of older model products into fast-growing waste streams. These products often contain a variety of metals, some of which are in high demand for their importance in technological applications but are in relatively short supply. These technology critical elements (TCE) are often insufficiently researched, and their natural abundance and behavior in environmental systems can be poorly understood or not known. This lack of comprehension creates a difficulty in tracing sources of their dissemination into the environment and an inadequacy in understanding the potential effects on environmental habitats. This thesis is an environmental forensics approach to tracing anthropogenically induced Cd and TCEs in sediments and groundwater in Kallholmsfjärdin, Northern Sweden. This area has been heavily industrialized since the early 1930s by Boliden Mineral AB's Cu-Pb-Zn smelter at Rönnskär. Process operations related to sulfide ore smelting, processing secondary scrap metals, and end-of-life electronics are all investigated. This thesis further attempts to identify anthropogenically induced changes to element mobility and influences on sediments in the Bothnian Bay's deeper basins.Paper-I was dedicated to tracing heavy metal contamination in groundwater monitoring wells around Rönnskär's waste deposit area. Sources of contamination were identified using multi-element screening analysis and multivariate statistical techniques such as principal component analysis and cluster analysis. Three sources of contamination were ultimately identified in the area. Principle component analysis was suggested to be a suitable method for the initial surveys prior to a full-scale monitoring program. However, to obtain more detailed information on specific element mobility and source identification, reactive-transport modeling and/or isotope analysis should be used.Paper-II explored the potential of Ta and Nb to serve as tracers for sediment contamination related to the processing of end-of-life electronics at Rönnskär. This paper further investigates changes in mobility related to anthropogenic activity and the possible transport into the Bothnian Bay. Two sediment cores were taken in Kallholm Bay and in the Bothnian Bays deeper basins. Sediments were analyzed using ICP-SFMS and ICP-OES. Identification of fractionated phases was analyzed through a 5-step sequential extraction procedure. The Nb/Ta ratio decreased from 14.5 to 1.7 due to an enrichment of Ta likely resulting from the processing of Ta-capacitor bearing electronics. An anthropogenic influence was also noticed in the partitioning of Ta with an increase in the hydrous ferric oxides (HFOs) and organic matter. This behavior was suggested to be a mechanism of the increase in the mobility of Ta into the Bothnian Bay. However, no increase in Bothnian Bay sediments was seen. Paper-III expanded on these results by investigating the remaining TCEs, including the REEs using the same sediments and methods. Several elements were found to increase in the sediments related to sulfide ore smelting (Ge, Te, Tl, and Re) and secondary scrap metal and end-of-life electronic processing (Ta and W). Gallium, Nb, and the REEs showed no influence from anthropogenic activity. Changes in mobility was observed due to anthropogenic influence for Ge, Tl, and Ta. Only Te showed an increase in the deeper Bothnian Bay sediments.
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