Juho Junttila

Baseline benthic foraminiferal assemblages and habitat conditions in a sub-Arctic region of increasing petroleum development

The aim of this study is to establish pre-impact baseline conditions for an Arctic region where petroleum activities are projected to increase in the coming decades. We characterize the spatial distribution of living benthic foraminifera in the Tromsøflaket-Ingøydjupet region of the Barents Sea and relate this to sediment properties and their associated metal concentrations. Metal concentrations of the sediments did not exceed threshold levels of harmful environmental effects, indicating that the area exhibits pre-impact baseline conditions. Foraminiferal assemblages reflect the pristine environment. Epifaunal species dominate in Tromsøflaket, a high energy environment characterized by coarse grained sediments. Infaunal species dominate in Ingøydjupet, a low energy environment characterized by fine grained sediments. Metal concentrations were slightly elevated in the fine grained sediments from Ingøydjupet which suggest that these areas may in the future serve as trapping zones for contaminants associated with discharges from nearby petroleum sites.

Benthic foraminifera as bio-indicators of chemical and physical stressors in Hammerfest harbor (Northern Norway)

We investigated benthic foraminiferal assemblages in contaminated sediments in a subarctic harbor of Northern Norway to assess their utility as indicators of anthropogenic impacts. Sediments in the harbor are repositories for POPs and heavy metals supplied through discharges from industry and shipping activities. Sediment contaminant concentrations are at moderate to poor ecological quality status (EcoQS) levels. The EcoQS based on benthic foraminiferal diversity reflects a similar trend to the EcoQS based on contaminant concentrations. Foraminiferal density and diversity is low throughout the harbor with distinct assemblages reflecting influence of physical disturbances or chemical stressors. Assemblages impacted by physical disturbance are dominated by L. lobatula and E. excavatum, while assemblages impacted by chemical stressors are dominated by opportunistic species S. fusiformis, S. biformis, B. spathulata and E. excavatum. The foraminiferal assemblage from an un-impacted nearby fjord consists mainly of agglutinated taxa. These assemblages provides a valuable baseline of the ecological impacts of industrialization in northern coastal communities.

The impact of submarine copper mine tailing disposal from the 1970s on Repparfjorden, northern Norway

We investigate the state of sedimentological environment and contaminant status of Repparfjorden (N Norway) impacted by submarine disposal of mine tailings during the 1970s using sedimentological and geochemical properties of seventeen sediment cores. The impact of tailings disposal is mainly restricted to the inner fjord where the discharge occurred. Sediment cores retrieved from the inner fjord contain layers of mine tailings up to 9-cm thick, 3-9cm below the seafloor. Spreading of the tailing-related metal Cu and particles is limited to the inner fjord and to a 2cm layer in one core from the outer fjord. Two interrelated factors, fjord morphology and sedimentation rate, controlled the distribution of contaminant-laden tailings in the fjord. The mobility of Cu from buried contaminated sediments to the sediment-water interface in the inner fjord indicates that benthic communities have been continuously exposed to elevated Cu concentrations for nearly four decades.

Benthic foraminiferal growth seasons implied from Mg/Ca-temperature correlations for three Arctic species

Core-top sediment samples from Kongsfjorden, Svalbard and adjacent fjord and shelf areas were collected in order to investigate a potential relationship between Mg/Ca-ratios of Arctic benthic foraminifera and the ambient bottom water temperatures (BWT). The area is influenced by large seasonal variation in factors such as light and temperature, which is further strengthened by oceanographic shifts, including inflow of relatively warm Atlantic water. Four hydrological seasons have been defined. The studied samples were collected during the years 2005-2010 and comprise data from three hydrological seasons: spring, summer and autumn. Five common species of cold-water benthic foraminifera were investigated: Islandiella helenae/norcrossi, Buccella frigida, Nonionellina labradorica, Elphidium clavatum and Cassidulina reniforme. For E. clavatum and C. reniforme, the investigations failed. For the remaining three species, the Mg/Ca-temperature correlations initially appeared stochastic holding correlation coefficients between 0.01 and 0.15. However, grouping the data based on seasons gave stronger Mg/Ca-temperature correlations, indicating specific growing seasons for the three species. The equations represent a starting point for a discussion on seasonality rather than robust, “ready-to-use” equations. I. helenae/norcrossi seem to reproduce and grow during summer (July/August) in outer Kongsfjorden. For B. frigida, a Mg/Ca-temperature correlation is seen both in summer (July/August) and autumn (October/November) samples, indicative of a continuous reproduction/growth-season lasting from July-November. N. labradorica appears to reproduce and grow during autumn (October/November). The results indicate that temperature reconstructions based on these benthic foraminifera reproduce seasonal temperatures rather than annual average temperatures. This article is protected by copyright. All rights reserved.

Identifying past petroleum exploration related drill cutting releases and influences on the marine environment and benthic foraminiferal communities, Goliat Field, SW Barents Sea, Norway

The present multiproxy investigation of marine sediment cores aims at: 1) Identifying dispersion of petroleum exploration related drill cutting releases within the Goliat Field, Barents Sea in 2006/07 and 2) Assessing past and present influence of drill cuttings on the marine environment. The cores were recovered 5, 30, 60, 125 and 250m from the drill site in the eastward downstream direction. Downstream dispersion of drill cuttings is evaluated by examining sediment grain size distribution and barium (Ba), heavy metal, total organic carbon and sulphur concentrations. Dispersion of drill cuttings was limited to <125m east from the drill site. Influence of drill cutting releases on the marine environment is assessed via microfaunal analysis of primarily calcareous benthic foraminifera. The findings suggest contemporaneous physical smothering at ≤30m from the drill site, with a natural fauna reestablishing after drilling cessation indicating no long-term effect of drill cutting releases.

Applying Chemometrics to Determine Dispersion of Mine Tailing-Affected Sediments from Submarine Tailing Disposal in Bøkfjorden, Northern Norway

Mine tailing management is one of the largest environmental issues related to mining operation. This study uses chemometrics to assess the dispersion of iron mine tailing-affected sediments in Bøkfjorden, Northern Norway. Metal concentrations (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) and physico-chemical sediment characteristics (conductivity, organic matter, sulphate, chloride, grain size, CaCO3, pH) were analysed in seven sediment cores collected in a transect out of the fjord along with two reference cores. Results of hierarchical cluster analysis and principal component analysis allowed to distinguish between mine tailing-affected and non-affected sediments. Non-affected sediments were especially characterised by high levels of organic matter whilst mine tailing-affected sediments varied significantly in sediment characteristics depending on location in the fjord. Crucial parameters to reveal mine tailing-affected sediments varied between the target metal Fe along with metals of Cd and Mn, albeit less significant. Variations in mine tailing-affected sediment characteristics could be attributed to other anthropogenic activities in the fjord. Despite potential disturbances, chemometrics made it possible to identify dispersion of mine tailing-affected sediments to cover the inner and middle parts of the fjord. The study demonstrates the advantage of applying chemometrics on complex fjord systems, which in this case was used to distinguish mine tailing-affected sediments from areas with elevated levels of metals not necessarily related to the mine.

Spreading of drill cuttings and sediment recovery of three exploration wells of different ages, SW Barents Sea, Norway

Five stations (≤250 m from the well heads) from three exploration wells of different ages from the SW Barents Sea were studied to investigate the spreading of drill cuttings and sediment quality. Two of the wells were drilled before the restriction of use of oil-based drilling fluids (1993). Elevated concentrations of Ba were found in sediments near all the wells with the highest concentrations at ≤60 m from the well head. The thickness of drill cutting layers was between >20 cm (well head) and 2 cm (250 m from the well head). The sediment quality varied from very bad (oldest well) to background (normal) (newer wells). Regulations led to better sediment quality. Metal concentrations from the oldest well suggested that the top 4 cm of the core represents sediment recovery. However, Ba concentrations of the top sediment layer at all the stations of the three wells indicate no physical recovery.

The influence of Magnafloc10 on the acidic, alkaline, and electrodialytic desorption of metals from mine tailings

Repparfjorden in northern Norway has been partly designated for submarine mine tailings disposal when the adjacent Cu mine re-opens in 2019. In order to increase sedimentation, the flocculant, Magnafloc10 is planned to be added to the mine tailings prior to discharge into the fjord. This study investigated the feasibility of reducing the Cu concentrations (375 mg/kg) in the mine tailings by applying electrodialytic extraction, including potential optimisation by adding Magnafloc10. In the acidic electrodialytic treatment (pH < 2), Magnafloc10 increased the extraction of Cu from the mine tailings particles from 76 to 86%, and the flocs with adsorbed metals were separated from the tailings solids by the electric field (1 mA/cm2). The electric energy consumption increased with the use of Magnafloc10 (from 17 to 30 kWh/g Cu extracted), due to lower conductivity in the liquid phase and clogging of the membrane by the flocs. In the alkaline electrodialytic treatment (pH > 12), Magnafloc10 reduced the extraction of Cu from 17% to 0.7%, due to the flocs remaining in the tailing slurries. The electric energy consumption per extracted Cu was similar in the acidic and alkaline electrodialytic treatments without the addition of Magnafloc10. In the alkaline electrodialytic treatment, the extraction of other metals was low (<2%), however longer treatment time is necessary to achieve similar Cu extraction as in the acidic electrodialysis. Depending on the target and timescale for treatment, acidic and alkaline electrodialysis can be employed to reduce the Cu concentration in the mine tailings thereby reducing the metal toxicity potential.