Description: Anthropogenic nutrient enrichment is changing the structure and the function of coastal ecosystems. These coastal zones are transitions between freshwater and marine systems where multiple biogeochemical processes remove, produce and transform organic matter. The extent to which the coastal zone is merely a conduit for terrestrial (allochthonous) organic matter, versus a distinct source of autochthonous organic matter fueled by eutrophication, is unclear. To address this issue, we characterized the freshwater and marine dissolved organic matter (DOM) pools in an eutrophic estuary with a long water residence time (Roskilde Fjord, Denmark) over an annual cycle. We combined elemental, optical (absorbance and fluorescence) and isotopic analyses to obtain insight about the bulk properties of the DOM pool during this period. We also used sediment traps to analyze the changes related to the exchange of organic matter between the particulate (POM) and dissolved (DOM) fractions. The results showed that labile autochthonous DOM from in situ primary production was rapidly transformed to more recalcitrant DOM that accumulated in the estuary despite continuous exchange with the open sea. Also, parts of the POM pool were degraded rapidly (within 24h) and transformed into the DOM pool. Accumulated DOM was characterized by relatively low molecular size and stable carbon isotopic value, and by high protein-like fluorescence. These results indicate that autotrophic material can be a major source of specific recalcitrant DOM in eutrophic coastal waters, contributing significantly to the flux of organic carbon to the ocean.

Description: Water samples collected from various depths of offshore South China and Philippine Seas were exposed to solar-simulated radiation. Photomineralization of dissolved organic carbon (DOC) and photobleaching of chromophoric DOM (CDOM) and its humic-like fluorescent constituent (FDOM) were observed in all samples.

Description: Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. Vertical distribution of temperature and salinity with a depth interval of 1 m were obtained by CTD.

Description: Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. Lab irradiation experiments of samples from different sampling depth were carried out. The samples were irradiated for 6 days under a SUNTEST XLS+ solar simulator equipped with a 1.5 kW xenon lamp and a special UV filter to remove radiation at wavelengths 〈290 nm. The samples before and after irradiation were defined as 'unirradiated samples' and 'irradiated samples', respectively. This table lists the chemical and optical properties of dissolved organic matter at different sampling depth before and after 6-d irradiation.

Description: Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. The percentage change of different parameters was calculated as the ratio of the signal difference of property X before and after irradiation to that before irradiation.

Description: Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. A time-course irradiation with sampling time at 0, 1, 3, 5, 7, and 10 d was conducted for the bottommost samples from SEATS and F2. The value of different parameters was calculated as the ratio of the signal of property X at irradiation time t to that at time zero.

Description: Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. A time-course dark incubation (50 days) with sampling time at 0, 3, 7, 11, 15, 23, 34 and 50 d was conducted for the bottommost sample from F2 with and without prior exposure to solar radiation. The value of different parameters was calculated as the ratio of the signal of property X at irradiation time t to that at time zero.

Description: Photosynthetic parameters for the TRANSSIZ expedition aboard the RV Polarstern (PS92, ARK-XXIX/1) between the 19th of May and the 26th June of 2015.

Description: In this study, we present unique data collected with a Surface and Under-Ice Trawl (SUIT) during five campaigns between 2012 and 2017, covering the spring to summer and autumn transition in the Arctic Ocean, and the seasons of winter and summer in the Southern Ocean. The SUIT was equipped with a sensor array from which we retrieved: sea-ice thickness, the light field at the underside of sea ice, chlorophyll a concentration in the ice (in-ice chl a), and the salinity, temperature, and chl a concentration of the under-ice water. With an average trawl distance of about 2 km, and a global transect length of more than 117 km in both polar regions, the present work represents the first multi-seasonal habitat characterization based on kilometer-scale profiles. The present data highlight regional and seasonal patterns in sea-ice properties in the Polar Ocean. Light transmittance through Arctic sea ice reached almost 100 in summer, when the ice was thinner and melt ponds spread over the ice surface. However, the daily integrated amount of light under sea ice was maximum in spring. Compared to the Arctic, Antarctic sea-ice was thinner, snow depth was thicker, and sea-ice properties were more uniform between seasons. Light transmittance was low in winter with maximum transmittance of 73. Despite thicker snow depth, the overall under-ice light was considerably higher during Antarctic summer than during Arctic summer. Spatial autocorrelation analysis shows that Arctic sea ice was characterized by larger floes compared to the Antarctic. In both Polar regions, the patch size of the transmittance followed the spatial variability of sea-ice thickness. In-ice chl a in the Arctic Ocean remained below 0.39 mg chl a m〈sup〉â��2〈/sup〉, whereas it exceeded 7 mg chl a m〈sup〉â��2〈/sup〉 during Antarctic winter, when water chl a concentrations remained below 1.5 mg chl a m〈sup〉â��2〈/sup〉, thus highlighting its potential as an important carbon source for overwintering organisms. The data analyzed in this study can improve large-scale physical and ecosystem models, habitat mapping studies and time series analyzed in the context of climate change effects and marine management.