Inorganic carbon time series at Ocean Weather Station M in the Norwegian Sea

International audienceDissolved inorganic carbon (CT) has been collected at Ocean Weather Station M (OWSM) in the Norwegian Sea since 2001. Seasonal variations in CT are confined to the upper 50 m, where the biology is active, and below this layer no clear seasonal signal is seen. From winter to summer the surface CT concentration typical drops from 2140 to about 2040 ?mol kg?1, while a deep water CT concentration of about 2163 ?mol kg?1 is measured throughout the year. Observations show an annual increase in salinity normalized carbon concentration (nCT) of 1.3±0.7 ?mol kg?1 in the surface layer, which is equivalent to a pCO2 increase of 2.6±1.2 ?atm yr?1, i.e. larger than the atmospheric increase in this area. Observations also show an annual increase in the deep water nCT of 0.57± 0.24 ?mol kg?1, of which about a tenth is due to inflow of old Arctic water with larger amounts of remineralised matter. The remaining part has an anthropogenic origin and sources for this might be Greenland Sea surface water, Iceland Sea surface water, and/or recirculated Atlantic Water. By using an extended multi linear regression method (eMLR) it is verified that anthropogenic carbon has entered the whole water column at OWSM

Decadal trends in ocean acidification from the Ocean Weather Station M in the Norwegian Sea

The Ocean Weather Station M (OWSM) is situated at a fixed position in the Norwegian Sea, one of the major basins of the Nordic Seas, which represents an important area for uptake of atmospheric CO2 as well as deep water formation. At OWSM, the inorganic carbon cycle has been regularly monitored since 2001, and significant interannual changes of the carbonate system have been determined. Data collected at this site since the 1990s have been included, and over the 28 last years the surface fugacity of CO2 (fCO2) has increased by 2.92 ± 0.37 μatm/yr, while surface pH and aragonite saturation (ΩAr) have decreased by -0.0033 ± 0.0005/yr and -0.018 ± 0.003/yr, respectively. This corresponds to a surface pH change of -0.092 over 28 years, which is comparable to the global mean pH decrease of -0.1 since the onset of the industrial revolution. Our estimates suggest that 80% of the surface pH trend at OWSM is driven by uptake of CO2 from the atmosphere. In the deepest layer, ΩAr has decreased significantly (-0.006 ± 0.001/yr) over the last 28 years, now occasionally reaching undersaturated values (ΩAr < 1). As a rough estimate, the saturation horizon has shoaled by 7 m/yr between 1994 and 2021. The increase in surface fCO2 is confirmed by semi-continuous measurements of CO2 from the site (2.69 ± 0.14 μatm/yr), and thus, the area has become less of a net sink for atmospheric CO2, taking into consideration an atmospheric CO2 increase at OWSM of 2.27 ± 0.08 μatm/yr.publishedVersio

The Nordic Seas carbon budget: Sources, sinks, and uncertainties

A carbon budget for the Nordic Seas is derived by combining recent inorganic carbon data from the CARINA database with relevant volume transports. Values of organic carbon in the Nordic Seas' water masses, the amount of carbon input from river runoff, and the removal through sediment burial are taken from the literature. The largest source of carbon to the Nordic Seas is the Atlantic Water that enters the area across the Greenland-Scotland Ridge; this is in particular true for the anthropogenic CO2. The dense overflows into the deep North Atlantic are the main sinks of carbon from the Nordic Seas. The budget show that presently 12.3 ± 1.4 Gt C yr−1 is transported into the Nordic Seas and that 12.5 ± 0.9 Gt C yr−1 is transported out, resulting in a net advective carbon transport out of the Nordic Seas of 0.17 ± 0.06 Gt C yr−1. Taking storage into account, this implies a net air-to-sea CO2 transfer of 0.19 ± 0.06 Gt C yr−1 into the Nordic Seas. The horizontal transport of carbon through the Nordic Seas is thus approximately two orders of magnitude larger than the CO2 uptake from the atmosphere. No difference in CO2 uptake was found between 2002 and the preindustrial period, but the net advective export of carbon from the Nordic Seas is smaller at present due to the accumulation of anthropogenic CO2

Fluxes of carbon and nutrients to the Iceland Sea surface layer and inferred primary productivity and stoichiometry

This study evaluates long-term mean fluxes of carbon and nutrients to the upper 100 m of the Iceland Sea. The study utilises hydro-chemical data from the Iceland Sea time series station (68.00° N, 12.67° W), for the years between 1993 and 2006. By comparing data of dissolved inorganic carbon (DIC) and nutrients in the surface layer (upper 100 m), and a sub-surface layer (100–200 m), we calculate monthly deficits in the surface, and use these to deduce the long-term mean surface layer fluxes that affect the deficits: vertical mixing, horizontal advection, air–sea exchange, and biological activity. The deficits show a clear seasonality with a minimum in winter, when the mixed layer is at the deepest, and a maximum in early autumn, when biological uptake has removed much of the nutrients. The annual vertical fluxes of DIC and nitrate amounts to 2.9 ± 0.5 and 0.45 ± 0.09 mol m−2 yr−1, respectively, and the annual air–sea uptake of atmospheric CO2 is 4.4 ± 1.1 mol C m−2 yr−1. The biologically driven changes in DIC during the year relates to net community production (NCP), and the net annual NCP corresponds to export production, and is here calculated as 7.3 ± 1.0 mol C m−2 yr−1. The typical, median C : N ratio during the period of net community uptake is 9.0, and clearly higher than the Redfield ratio, but is varying during the season.publishedVersio

Seasonal variations of hydrographic parameters off the Sudanese coast of the Red Sea, 2009–2015

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Regional Studies in Marine Science 18 (2018): 1-10, doi:10.1016/j.rsma.2017.12.004.The variations of temperature and salinity in the Sudanese coastal zone of the Red Sea are studied for the first time using measurements acquired from survey cruises during 2009–2013 and from a mooring during 2014–2015. The measurements show that temperature and salinity variability above the permanent pycnocline is dominated by seasonal signals, similar in character to seasonal temperature and salinity oscillations observed further north on the eastern side of the Red Sea. Using estimates of heat flux, circulation and horizontal temperature/salinity gradients derived from a number of sources, we determined that the observed seasonal signals of temperature and salinity are not the product of local heat and mass flux alone, but are also due to alongshore advection of waters with spatially varying temperature and salinity. As the temperature and salinity gradients, characterized by warmer and less saline water to the south, exhibit little seasonal variation, the seasonal salinity and temperature variations are closely linked to an observed seasonal oscillation in the along-shore flow, which also has a mean northward component. We find that the inclusion of the advection terms in the heat and mass balance has two principal effects on the computed temperature and salinity series. One is that the steady influx of warmer and less saline water from the south counteracts the long-term trend of declining temperatures and rising salinities computed with only the local surface flux terms, and produces a long-term steady state in temperature and salinity. The second effect is produced by the seasonal alongshore velocity oscillation and most profoundly affects the computed salinity, which shows no seasonal signal without the inclusion of the advective term. In both the observations and computed results, the seasonal salinity signal lags that of temperature by roughly 3 months.The SPS surveys were funded by the Norwegian Norad’s Program for Master Studies and organized by IMR–RSU in Port Sudan. The central Red Sea mooring data were acquired as part of a WHOI–KAUST collaboration funded by Award Nos. USA00001, USA00002, and KSA00011 to the WHOI by the KAUST in the Kingdom of Saudi Arabia. The work of I. Skjelvan and A.M. Omar was partly supported by the Research Council of Norway through the MIMT Center for Research-based Innovation. This work is part of a Ph.D. project at GFI–UiB funded by the Norwegian Quota program

Parenteral Nutrition in Advanced Cancer: The Healthcare Providers’ Perspective

Introduction: The evidence base for parenteral nutrition (PN) in advanced cancer patients is limited. We studied healthcare providers’ (HCPs’) experiences with PN in cancer patients, focusing on perceived treatment benefits and challenges. Methods: An 18-item online survey was emailed to HCPs attending one of three regional palliative care seminars held within a 6-month period. The survey included single-response items, multiple-response items, and free text boxes concerning PN. Descriptive statistics and qualitative thematic content analysis were applied. Results: One hundred and two seminar participants completed the survey. Ninety-three percent were female, 86% were nurses/oncological nurses, and 80% worked in primary care. Respondents reported a well-functioning collaboration across levels of care. They perceived that PN may increase the patients’ level of energy, improve the general condition, and reduce eating-related distress. On the downside, HCPs observed burdensome side effects, that the treatment was resource-demanding, and that decisions on PN withdrawal were difficult. Conclusion: The study results are based on the perspectives of more than 100 HCPs with comprehensive clinical experience with PN. Their knowledge represents an important experience base for improvement of healthcare services and advanced care planning.publishedVersio

Overview of the Nordic Seas CARINA data and salinity measurements

Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS), the Atlantic (ATL) and the Southern Ocean (SO). With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004) and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas include the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution provides an overview of the CARINA data from the Nordic Seas and summarises the findings of the QC of the salinity data. One cruise had salinity data that were of questionable quality, and these have been removed from the data product. An evaluation of the consistency of the quality controlled salinity data suggests that they are consistent to at least ±0.005

Norwegian Sea net community production estimated from O2 and prototype CO2 optode measurements on a Seaglider

We report on a pilot study using a CO2 optode deployed on a Seaglider in the Norwegian Sea from March to October 2014. The optode measurements required drift and lag correction and in situ calibration using discrete wa ter samples collected in the vicinity. We found that the op tode signal correlated better with the concentration of CO2, c(CO2), than with its partial pressure, p(CO2). Using the calibrated c(CO2) and a regional parameterisation of to tal alkalinity (AT) as a function of temperature and salin ity, we calculated total dissolved inorganic carbon content, c(DIC), which had a standard deviation of 11 μmol kg-2 compared with in situ measurements. The glider was also equipped with an oxygen (O2) optode. The O2 optode was drift corrected and calibrated using a c(O2) climatology for deep samples. The calibrated data enabled the calcu lation of DIC-and O2-based net community production, N(DIC) and N(O2). To derive N, DIC and O2 inventory changes over time were combined with estimates of air sea gas exchange, diapycnal mixing and entrainment of deeper waters. Glider-based observations captured two periods of increased Chl a inventory in late spring (May) and a second one in summer (June). For the May period, we found N(DIC) = (21±5) mmol m-2 d-1 , N(O2) = (94± 16) mmol m-2 d-1 and an (uncalibrated) Chl a peak con centration of craw(Chl a) = 3 mg m-3. During the June pe riod, craw(Chl a) increased to a summer maximum of 4 mg m-3 , associated with N(DIC) = (85±5) mmol m-2 d-1 and N(O2) = (126±25) mmol m-2 d -1. The high-resolution dataset allowed for quantification of the changes in N be fore, during and after the periods of increased Chl a inven tory. After the May period, the remineralisation of the mate rial produced during the period of increased Chl a inventory decreased N(DIC) to (-3 ± 5) mmol m-2 d-1 and N(O2) to (0 ± 2) mmol m-2 d-1 . The survey area was a source of O2 and a sink of CO2 for most of the summer. The deployment captured two different surface waters influenced by the Nor wegian Atlantic Current (NwAC) and the Norwegian Coastal Current (NCC). The NCC was characterised by lower c(O2) and c (DIC) than the NwAC, as well as lower N(O2) and craw(Chl a) but higher N(DIC). Our results show the poten tial of glider data to simultaneously capture time-and depth resolved variability in DIC and O2 concentrations