Search

Abstract: Phytoplankton carbon and nitrogen production in newly opened waters of the Western Arctic Ocean were measured using a 13C–15N dual isotope tracer technique in summer 2008, when Arctic sea ice was at its second lowest extent since 1979. Daily integrated carbon-uptake rates were highest (675.8±931.3mgCm–2 d–1) in ice-free shelf regions of the Chukchi Sea. In deeper regions, the daily integrated carbon-uptake rates (73.5±45.0mgCm–2 d–1) in newly opened deep waters with adjacent sea ice cover (10–90%) were significantly higher than those (32.0±22.8mgCm–2 d–1) in ice-free deep waters. The average contributions of small cell-size phytoplankton (0.7–5μm) to total carbon-uptake rates were 19.8%, 62.8%, and 55.5% in shelf regions, ice-free deep waters, and newly opened waters, respectively, although the average biomass contributions of the small phytoplankton was 54.9–96.5% of total algal biomass in the three study areas. Daily total nitrogen-uptake rates were similar between newly opened deep waters and ice-free deep waters, although nitrate assimilation rates were higher in newly opened waters compared to ammonium uptake rates in ice-free waters. Lower carbon- and nitrate-assimilation rates in ice-free waters were due to strong stratification in the euphotic layer caused by melted sea ice, which limited nutrient availability to phytoplankton, although phytoplankton had greater light availability in ice-free waters than in newly opened waters. [Copyright &y& Elsevier]

Abstract: Neutral polyfluorinated alkyl substances (PFASs) were measured in high-volume air samples collected on board the research vessel Snow Dragon during the 4th Chinese National Arctic Expedition from the Japan Sea to the Arctic Ocean in 2010. Four volatile and semi-volatile PFASs (fluorotelomer alcohols (FTOHs), fluorotelomer acids (FTAs), perfluoroalkyl sulfonamides (FASAs), and sulfonamidoethanols (FASEs)) were analyzed respectively in the gas and particle phases. FTOHs were the dominant PFASs in the gas phase (61–358pgm−3), followed by FTAs (5.2–47.9pgm−3), FASEs (1.9–15.0pgm−3), and FASAs (0.5–2.1pgm−3). In the particle phase, the dominant PFAS class was FTOHs (1.0–9.9pgm−3). The particle-associated fraction followed the general trend of FASEs>FASAs>FTOHs. Compared with other atmospheric PFAS measurements, the ranges of concentrations of ∑FTOH in this study were similar to those reported from Toronto, north America (urban), the northeast Atlantic Ocean, and northern Germany. Significant correlations between FASEs in the gas phase and ambient air temperature indicate that cold surfaces such as sea-ice, snowpack, and surface seawater influence atmospheric FASEs. [Copyright &y& Elsevier]