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We investigated the distributions of the artificial radionuclides 137Cs, 239+240Pu, and 90Sr in the various marine products around Korean Peninsula collected in 2015–2017. The activities of 137Cs, 239+240Pu, and 90Sr were in the ranges of 12.2–258.4 mBq kg−1, 0.014–1.879 mBq kg−1, and 11.3–18.3 mBq kg−1, respectively. The higher 239+240Pu (a factor of 10–50) relative to fishes were observed in mollusks. 137Cs in fishes were significantly enriched with growths. The calculated concentration factors (CFs) of 137Cs, 239+240Pu, and 90Sr in marine products were 7–143, 3–407, and 15–25, respectively. Overall, no noticeable artificial radioactivity was detected in marine organisms when comparing these results with previous data reported before the Fukushima nuclear accident and recommended CF values. The annual effective doses of 137Cs, 239+240Pu, and 90Sr by seafood consumption in South Korea were estimated to be 1.1 × 10−4, 1.6 × 10−5 and, 2.9 × 10−5 mSv yr−1, respectively, which is insignificant relative to that of natural radionuclides. • Artificial radionuclides (ARs) were determined in marine products around South Korea. • No significant spatiotemporal variation of 137Cs, 239,240Pu, 90Sr in marine biota • 137Cs and 239,240Pu in marine biota could vary according to main habitats and growth. • 137Cs activity in fishes except salmon logarithmically correlated with body weight. • Annual dose of ARs were insignificant relative to those of natural radionuclides. [ABSTRACT FROM AUTHOR]

We investigated horizontal and vertical distributions of DMS in the upper water column of the Amundsen Sea Polynya and Pine Island Polynya during the austral summer (January–February) of 2016 using a membrane inlet mass spectrometer (MIMS) onboard the Korean icebreaker R/V Araon . The surface water concentrations of DMS varied from < 1 to 400 nM. The highest DMS (up to 300 nM) were observed in sea ice–polynya transition zones and near the Getz ice shelf, where both the first local ice melting and high plankton productivity were observed. In other regions, high DMS concentration was generally accompanied by higher chlorophyll and ΔO 2 /Ar. The large spatial variability of DMS and primary productivity in the surface water of the Amundsen Sea seems to be attributed to melting conditions of sea ice, relative dominance of Phaeocystis Antarctica as a DMS producer, and timing differences between bloom and subsequent DMS productions. The depth profiles of DMS and ΔO 2 /Ar were consistent with the horizontal surface data, showing noticeable spatial variability. However, despite the large spatial variability, in contrast to the previous results from 2009, DMS concentrations and ΔO 2 /Ar in the surface water were indistinct between the two major domains: the sea ice zone and polynya region. The discrepancy may be associated with inter-annual variations of phytoplankton assemblages superimposed on differences in sea-ice conditions, blooming period, and spatial coverage along the vast surface area of the Amundsen Sea. [ABSTRACT FROM AUTHOR]

Rare earth element (REE) concentrations were measured for the first time in plankton from the northwestern Mediterranean Sea. The REE concentrations in phytoplankton (60–200 μm) were 5–15 times higher than those in four size fractions of zooplankton: 200–500 μm, 500–1000 μm, 1000–2000 μm and >2000 μm. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE 3+ , concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters. [ABSTRACT FROM AUTHOR]