Marine carbonyl sulfide (OCS) and carbon disulfide (CS2): a compilation of measurements in seawater and the marine boundary layer

Carbonyl sulfide (OCS) and carbon disulfide (CS2) are volatile sulfur gases that are naturally formed in seawater and exchanged with the atmosphere. OCS is the most abundant sulfur gas in the atmosphere, and CS2 is its most important precursor. They have gained interest due to their direct (OCS) or indirect (CS2 via oxidation to OCS) contribution to the stratospheric sulfate aerosol layer. Furthermore, OCS serves as a proxy to constrain terrestrial CO2 uptake by vegetation. Oceanic emissions of both gases contribute a major part to their atmospheric concentration. Here we present a database of previously published and unpublished, mainly ship-borne measurements in seawater and the marine boundary layer for both gases, available at https://doi.pangaea.de/10.1594/PANGAEA.905430 (Lennartz et al., 2019). The database contains original measurements as well as data digitalized from figures in publications from 42 measurement campaigns, i.e. cruises or time series stations, ranging from 1982 to 2019. OCS data cover all ocean basins except for the Arctic Ocean, as well as all months of the year, while the CS2 dataset shows large gaps in spatial and temporal coverage. Concentrations are consistent across different sampling and analysis techniques for OCS. The database is intended to support the identification of global spatial and temporal patterns and to facilitate the evaluation of model simulations

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit

Sea-surface dimethylsulfide (DMS) concentration from satellite data at global and regional scales

The marine biogenic gas dimethylsulfide (DMS) modulates climate by enhancing aerosol light scattering and seeding cloud formation. However, the lack of time-and space-resolved estimates of DMS concentration and emission hampers the assessment of its climatic effects. Here we present DMSSAT, a new remote sensing algorithm that relies on macroecological relationships between DMS, its phytoplanktonic precursor dimethylsulfoniopropionate (DMSPt) and plankton light exposure. In the first step, planktonic DMSPt is estimated from satellite-retrieved chlorophyll a and the light penetration regime as described in a previous study (Gali et al., 2015). In the second step, DMS is estimated as a function of DMSPt and photosynthetically available radiation (PAR) at the sea surface with an equation of the form: log(10)DMS = alpha + beta log(10)DMSPt + gamma PAR. The two-step DMSSAT algorithm is computationally light and can be optimized for global and regional scales. Validation at the global scale indicates that DMSSAT has better skill than previous algorithms and reproduces the main climatological features of DMS seasonality across contrasting biomes. The main shortcomings of the global-scale optimized algorithm are related to (i) regional biases in remotely sensed chlorophyll (which cause underestimation of DMS in the Southern Ocean) and (ii) the inability to reproduce high DMS = DMSPt ratios in late summer and fall in specific regions (which suggests the need to account for additional DMS drivers). Our work also highlights the shortcomings of interpolated DMS climatologies, caused by sparse and biased in situ sampling. Time series derived from MODIS-Aqua in the subpolar North Atlantic between 2003 and 2016 show wide interannual variability in the magnitude and timing of the annual DMS peak(s), demonstrating the need to move beyond the classical climatological view. By providing synoptic time series of DMS emission, DMSSAT can leverage atmospheric chemistry and climate models and advance our understanding of plankton-aerosol-cloud interactions in the context of global change

Biological turnover of DMS, DMSP and DMSO in contrasting open-sea waters

11 pages, 2 figures, 3 tablesSpeciation and turnover of the methylated sulfur compounds dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO) were studied in waters of the open western Mediterranean, the near-coastal North Sea and the subpolar North Atlantic, with chlorophyll a concentrations spanning 2 orders of magnitude (0.12 to 13 μg 1-1>). Particulate DMSP (DMSP(p): 5 to 340 nM) was the predominant pool in most waters. Dissolved and particulate dimethyl sulfoxide were alsofound at significant concentrations (DMSO(d): 2 to 25 nM, DMSO(p): 3 to 16 nM). Biological DMSP consumption rates were estimated from the time course of total (dissolved + particulate) DMSP Concentration in dark incubations Dimethyl sulfide production and consumption rates were determined by the 'inhibitor addition' method. High DMS production and consumption rates were found during a bloom of Phaeocystis sp. in North Sea waters. In all samples, turnover time constants for total DMSP and DMS were of the same order, ranging from 0.7 to 5.4 and from 0.3 to 2.1 d, respectively. DMS formation was the fate for 9 to 96% of the DMSP consumed. Use of chloroform as an inhibitor gave estimates of DMS production and consumption rates approximately 70% higher than those obtained with dimethyl disulfide and dimethyl selenide. In some incubation experiments, the time course of DMSO concentration has been followed along with DMS and DMSP for the first time. Evidence for active biological cycling (production and consumption) of DMSO in seawater is presentedPeer Reviewe

Atmospheric dry deposition of persistent organic pollutants to the Atlantic and inferences for the global oceans.

Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of persistent organic pollutants (POPs). A new methodology that combines aerosol remote sensing measurements with measured POP aerosol-phase concentrations is presented to derive dry particulate depositional fluxes of POPs to the oceans. These fluxes are compared with those due to diffusive air−water exchange. For all polychlorinated biphenyl (PCB) congeners and lower chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), air−water exchange dominates the dry deposition mechanism. However, this tendency reverses in some areas, such as in marine aerosol influenced areas and dust outflow regions, consistent with the important variability encountered for the depositional fluxes. Seasonal variability is mainly found in mid-high latitudes, due to the important influence of wind speed enhancing dry deposition fluxes and temperature as a driver of the gas-particle partitioning of POPs. The average dry aerosol deposition flux of ΣPCBs and ΣPCDD/Fs to the Atlantic Ocean is calculated to be in the order of 66 ng m-2 yr-1 and 9 ng m-2 yr-1 respectively. The total dry aerosol deposition of ∑PCBs and ∑PCDD/Fs to the Atlantic Ocean is estimated to be 2200 kg yr-1 and 500 kg yr-1, respectively, while the net air−water exchange is higher, 22000 kg ∑PCBs yr-1 for PCBs and 1300 kg ∑PCDD/Fs yr-1. Furthermore, it is suggested that marine aerosol plays an important role in scavenging atmospheric contaminants

Remote Sensing Retrieval of Isoprene Concentrations in the Southern Ocean

Isoprene produced by marine phytoplankton acts as a precursor of secondary organic aerosol and thereby affects cloud formation and brightness over the remote oceans. Yet the marine isoprene emission is poorly constrained, with discrepancies among estimates that reach 2 orders of magnitude. Here we present ISOREMS, the first satellite‐only based algorithm for the retrieval of isoprene concentration in the Southern Ocean. Sea surface concentrations from six cruises were matched with remotely sensed variables from MODIS Aqua, and isoprene was best predicted by multiple linear regression with chlorophyll a and sea surface temperature. Climatological (2002–2018) isoprene distributions computed with ISOREMS revealed high concentrations in coastal and near‐island waters, and within the 40–50°S latitudinal band. Isoprene seasonality paralleled phytoplankton productivity, with annual maxima in summer. The annual Southern Ocean emission of isoprene was estimated at 63 Gg C yr−1. The algorithm can provide spatially and temporally realistic inputs to atmospheric and climate models

Annual DMSP contribution to S and C fluxes through phytoplankton and bacterioplankton in a NW Mediterranean coastal site

The contribution of dimethylsulfoniopropionate (DMSP) to the fluxes of carbon and sulfur through phytoplankton and bacterioplankton was investigated throughout an annual cycle in the Blanes Bay Microbial Observatory (coastal NW Mediterranean). DMSP accounted for 0.3 to 7 % of biovolume-estimated phytoplankton carbon and 4 to 93 % of calculated phytoplankton sulfur, with higher contributions in `summer' (highly irradiated, oligotrophic waters, May to September) and lower in `winter' (October to April). DMSP biosynthesis rates accounted for 0.8 to 7 % of carbon fixation and 11 to 88 % of sulfur assimilation through primary production, with slightly higher shares in summer. Upon release from the algal cells, DMSP supplied 0.5 to 6 % of the total carbon demand of heterotrophic bacteria, and 3 to 100 % of the sulfur demand over the year. Uncertainties associated with these calculations are due to a scarce knowledge of C:S ratios in marine bacteria. Bacterial DMSP-sulfur assimilation (measured with (35)S-DMSP) was positively correlated with bacterial heterotrophic production rates (measured with (3)H-leucine). In summer waters, characterized by higher ratios of particulate DMSP to chlorophyll a (DMSP(p):chl a), DMSP-sulfur assimilation by bacteria was higher and contributed a larger share of the bacterial sulfur demand. We propose that the DMSP:chl a ratio is a good indicator of the relative role of DMSP in the carbon and sulfur fluxes through the first levels of the planktonic food web