JoLynn Carroll

Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the White Sea, Russia

The extent of environmental contamination and sources of polycyclic aromatic hydrocarbon (PAH) compounds to sediments of the White Sea are evaluated and compared with previously published results for adjacent Arctic Sea areas. Concentrations of two- to six-ring PAHs of molecular mass 128–278 including perylene and sediment characteristics are considered in this investigation. Mean ΣPAH concentration was 61±34 ng/g dw (n=11) for all samples and 87±43 ng/g dw (n=6) for pelite-rich samples (>83% pelite). These concentrations are 2–3 times lower than were previously reported for the SE Barents Sea. Concentrations of ΣPAH and ΣCPAH in the central White Sea have increased by a factor of 2-5 over pre-industrial background levels based on 210Pb age-dating of one sediment core. Using principal component analysis (PCA), two common factors explained 87.5% of the total variance for the White Sea data. Factor 1 is associated with high-temperature combustion processes and is related to emissions from a local aluminium smelter. Factor 2 is associated mainly with the introduction of petrogenic PAH compounds and perylene into Dvina Bay via the Severnaya Dvina River. A comparison of the White Sea and SE Barents Sea data indicates that similarities exist in the composition of parent PAH compounds. However, based on a comparative analysis of parent PAH ratios and relative contents of alkyl-substituted homologues, a common atmospheric source of anthropogenic pollutants can be ruled out. Further investigations are needed to determine whether sedimentary PAH signatures in areas of the Barents Sea that are in closer proximity to the White Sea are related to emissions from the aluminium smelter.

Electron microprobe analysis of juvenile walleye pollock, Theragra chalcogramma, otoliths from Alaska: a pilot stock separation study

SynopsisThe incorporation of dissolved oceanic constituents in the otoliths of fish has potential as a chemical tracer for reconstructing the early life history of marine fish. Wavelength dispersive spectrometers on an electron microprobe were used to measure Na, Mg, P, S, Cl, K, Ca, and Sr concentrations on the outer margins of 57 juvenile walleye pollock, Theragra chalcogramma, otoliths from five locations in the Gulf of Alaska and Bering Sea. Discriminant analyses that used various combinations of Na, P, K, Sr, and fish standard length and/or age showed that 60–80% of the samples could be assigned to the correct capture locality. While the concentrations of some of the measured elements correlated with standard length or age of the fish, there are measurable differences among localities when concentrations are length or age corrected, mainly due to differences in Na and K concentrations. Elemental composition of otoliths potentially could be used to assign fish from a mixed stock fishery to original stocks, information that is greatly needed for the effective management of fish stocks.

Snow and ice concentrations of selected persistent pollutants in the Ob–Yenisey River watershed

As one of the largest river systems attached to the Arctic Basin, the Ob-Yenisey watershed has the potential to be a major supply route of persistent organic pollutants into marine ecosystems of the Arctic Ocean. Snowfall and ice formation taking place in the Ob-Yenisey river basin and shelf are key components of the system of processes responsible for the transfer of pollutants from this high latitude river to the adjacent Kara and Barents Seas. Here we examine a large data set on persistent organic pollutants in snow and ice determined for areas within the Ob (interior and coastal), Yenisey and adjacent shelf. Data on the levels of total oil hydrocarbons, as well as individual components for groups (PAHs, HCHs, CBs, DDTs, PCBs) were examined in this investigation for two time periods: winter (1992)-spring (1993) and winter (1993)-spring (1994). Spatial averaging of each data set for individual years was performed in order to identify large-scale geographical trends in contaminant distributions within the four regions. The analysis indicates that mean pollutant concentrations in snow are consistent throughout the watershed. Comparing data from 1992/1993 and 1993/1994, in all cases, concentrations do not vary appreciatively among the different regions. A similar finding was observed for concentrations of pollutants in ice. Persistent organic pollutants for the Ob-Yenisey watershed are in most cases not dissimilar to measurements carried out in the far north of Canada. The exception is summation operator DDT. Concentrations of this pollutant are an order of magnitude higher in the Ob-Yenisey watershed as compared to the Canadian Arctic (0.09 ng/l).

Bioaccumulation of phenanthrene and benzo[a]pyrene in Calanus finmarchicus

With petroleum exploration and development expanding in the Arctic (AMAP, 2007) there is a need to obtain additional information on the ecotoxicology of Arctic organisms. Here we perform 192 h laboratory exposure experiments on the keystone Arctic zooplankton species, Calanus finmarchicus. We trace the accumulation and depuration of two polycyclic aromatic hydrocarbons (PAHs): phenanthrene and benzo[a]pyrene (B[a]P) using (14)C labeled PAH compounds. Copepods were not fed during the experiment, limiting uptake to diffusion processes alone. The lighter PAH compound, phenanthrene, accumulated rapidly in C. finmarchicus, reaching steady state within 96 h. The heavier PAH compound, B[a]P, accumulated more slowly and steady state was not reached within the 192 h exposure period. As expected, the bioconcentration factor (BCF) for B[a]P was higher than for phenanthrene in accordance with a higher octanol/water partition coefficient for B[a]P (log K(ow)=6.04) compared to phenanthrene (log K(ow)=4.53). However, for both compounds, log BCF was lower than log K(ow) that may indicate active biotransformation and excretion of the selected PAH compounds. These findings on the bio-uptake kinetics for petroleum hydrocarbons are essential for evaluating the potential consequences of an oil spill in the Arctic.

Transport processes in the Kara Sea

Field data from late summer cruises in 1993–1996 and results from a rotating laboratory model study are used to infer transport routes for contaminants in the Kara Sea on the western Siberian coast. The data show a circulation pattern that differs significantly from published concepts and contains a richer structure. Both the inflowing coastal water from the west and the modified Atlantic Water from the Barents Sea and the Arctic Ocean in the north affect the water properties of the East Novaya Zemlya Trough through mixing, intrusion, and possible transformation during winter convection. Much of the current structure can be explained as a result of topographical steering of the throughflows. Weak summer winds of variable direction affect only the upper layer, whereas persistent strong winds may affect long-term circulation patterns and transports. The main outflow routes are north to the Santa Anna Trough and northeast to the Voronin Trough. The outflowing surface water and ice to the north are expected to join the inflowing Polar Water from the Arctic Ocean that forms the Persey Current into the Barents Sea. Deeper outflows are expected to follow the continental slope to the east in the Arctic Ocean. The laboratory model has been validated to earlier current measurements to the north and south of Novaya Zemlya and shows several of the features observed in the newer field measurements. This suggests that the dynamic similitude and boundary forcing of the model are good. Two notable exceptions are the westward transport of drifting buoys to the north of Novaya Zemlya and the late winter hydrography to the north of the Ob and Yenisey estuaries. Both are probably due to persistent winds. The conclusions from the measured and modeled currents are supported by measurements of 137Cs in the seawater and sediments.

Arctic versus temperate comparison of risk assessment metrics for 2-methyl-naphthalene.

Reliable risk assessment approaches for Arctic environments are requested to manage potential impacts associated with increased activities in Arctic regions. We performed toxicity tests on Arctic and temperate species exposed to the narcotic acting oil component, 2-methyl naphthalene. The experimental results were used to quantify concentration causing lethality to 50% of exposed individuals and no-effect concentration (individual level). For estimates at community level, the hazardous concentrations affecting 5% and 50% of the species were calculated from sensitivity distribution curves. These survival metrics were then used to elucidate whether temperate toxicity data used in risk assessment are sufficiently representative for the Arctic. Taking data uncertainty into consideration, we found no regional difference in tolerances to 2-methyl naphthalene either at the species level or at the community level. Hence these data support a conclusion that values of survival metrics for temperate regions are transferrable to the Arctic for the chemical 2-methyl naphthalene, as long as extrapolation techniques are properly applied and uncertainties are taken into consideration.

Distribution coefficients (Kd's) for use in risk assessment models of the Kara Sea

As a prerequisite for most evaluations of radionuclide transport pathways in marine systems, it is necessary to obtain basic information on the sorption potential of contaminants onto particulate matter. Kd values for use in modeling radionuclide dispersion in the Kara Sea have been determined as part of several international programs addressing the problem of radioactive debris residing in Arctic Seas. Field and laboratory Kd experiments were conducted for the following radionuclides associated with nuclear waste: americium, europium, plutonium, cobalt, cesium and strontium. Emphasis has been placed on two regions in the Kara Sea: (i) the Novaya Zemlya Trough (NZT) and (ii) the mixing zones of the Ob and Yenisey Rivers (RMZ). Short-term batch Kd experiments were performed at-sea on ambient water column samples and on samples prepared both at-sea and in the laboratory by mixing filtered bottom water with small amounts of surficial bottom sediments (particle concentrations in samples = 1-30 mg/l). Within both regions, Kd values for individual radionuclides vary over two to three orders of magnitude. The relative particle affinities for radionuclides in the two regions are americium approximately equal to europium > plutonium > cobalt > cesium > strontium. The values determined in this study agree with minimum values given in the IAEA Technical Report [IAEA, 1985. Sediment Kds and Concentration Factors for Radionuclides in the Marine Environment. Technical Report No. 247. International Atomic Energy Agency, Vienna.]. Given the importance of Kds in assessments of critical transport pathways for radionuclide contaminants, we recommend that Kd ranges of values for specific elements rather than single mean values be incorporated into model simulations of radionuclide dispersion.

Geochronology of Lake Baikal from 210Pb and 137Cs radioisotopes

Abstract Two box cores of near surface sediments were obtained from Lake Baikal in Southeastern Siberia, Russia. The cores were taken from the northern and southern basins of the lake during a joint American–Russian research expedition in the summer of 1994. The cores were analyzed for 210Pb, 137Cs and total organic carbon (TOC). Organic carbon is an indicator of photosynthetic production by phytoplankton, taking place primarily in the euphotic zone of the water column. Accumulation rates of TOC may be used as indicators of paleo-productivity when sedimentation rates are determined using the 210Pb dating method and combined with both the density of sediment and organic carbon content. Accordingly, the lake is characterized by changes in accumulations of TOC, which may be linked to rates of sedimentation. Accumulations of TOC and sedimentation rates were higher in the southern basin site than in the northern basin site. The southern station core was taken from an area in close proximity to the Selenga River delta, which carries 50% of the water input to Lake Baikal. Productivity should thus be higher in this region due to the high nutrient input and sediment accumulation higher due to influx of riverine sediment input. Traces of 137Cs (an anthropogenic product) were found in both cores. However, activities of 137Cs were significantly higher in the southern basin, likely due to the input of the Selenga River in the southern region, which extends to a region in Mongolia in close proximity to the area of the Chinese atomic-bomb atmospheric testing of the 1970s. Application of a quantitative inverse model to the 210Pb profiles yielded the following results: (i) station 12, near the Selenga Delta, had an accumulation rate of about 0.38 cm/y in 1957 but this rate was halved by 1980 to about 0.22 cm/y and has been roughly steady since that time; 137Cs values are consistent with the age-to-depth determination from 210Pb for station 12; (ii) since about 1960, station 5A in the northern basin had an accumulation rate lower by a factor 2–4 than that of the station near the Selenga Delta; the 137Cs values are consistent with the 210Pb age-to-depth determination for station 5A; (iii) the 137Cs activities for station 12 systematically increase with time towards the present day and are about a factor 6–10 higher than 137Cs activities recorded for station 5A, which do not show a corresponding systematic increase with time.

Radionuclide adsorption to sediments from nuclear waste dumping sites in the Kara Sea

Environmental parameters (salinity, sediment concentration, equilibration time) affecting radionuclide partitioning between sediment and seawater were experimentally investigated for Kara Sea sediments collected from nuclear waste dumping sites in Abrosimov and Stepovogo Bays off Novaya Zemlya. Adsorption kinetics were examined and the influence of salinity and sediment concentration were evaluated over the range of concentrations expected in the bays for the following radionuclides: 110 m Ag; 241 Am; 109 Cd; 60 Co; 57 Co-cobalamine; 134 Cs; 152 Eu; 54 Mn; 133 Ba; 106 Ru; and 85 Sr. The major findings of this investigation are that : 1) radionuclide distribution coefficients (K d s) were most sensitive to variations in sediment character ( 241 Am, 60 Co, 109 Cd) and concentration ( 57 Co-cobalamine, 85 Sr, and 133 Ba), 2) distribution coefficients generally decreased with increasing sediment concentration and 3) fast adsorption kinetics (near equilibrium 1 day) were observed only for 137 Cs and 110 m Ag. The observed differences in K d s for sediments from the two dumpsites exemplifies the importance of undertaking site-specific determinations of K d s. For purposes of confining radioactive wastes to the dumpsites in Stepovogo and Abrosimov Bays, the findings of this study indicate that based on sediment character alone, Stepovogo Bay will be more effective at retaining radionuclides than Abrosimov Bay. This is unfortunate since less radioactive waste resides in Stepovogo Bay (0.6 PBq) than in Abrosimov Bay (1.4 PBq).

Summary of IAEA-MEL's investigation of Kara Sea radioactivity and radiological assessment

IAEA-MEL participated in five expeditions to the Kara Sea with the aim of assessing the radiological consequences of dumped radioactive wastes in the Novaya Zemlya Bays and Trough. The programme included sampling, in-situ underwater investigations, laboratory analyses of water, sediment and biota samples, the development of a marine radioactivity database, modelling and radiological assessment, the organization of intercomparison exercises and the evaluation of distribution coefficients. Radiometric investigations have shown that no radiologically significant environmental contamination has occurred. Leakages which have led to locally increased levels of radionuclides in sediment have only been observed in Stepovoy and Abrosimov Bays. Computer modelling results suggest that only radiological effects on local and regional scales may be of importance. The global radiological impact of the disposals in the Arctic Seas will be negligible.