17 research outputs found
The role of a changing Arctic Ocean and climate for the biogeochemical cycling of dimethyl sulphide and carbon monoxide
Dimethyl sulphide (DMS) and carbon monoxide(CO) are climate-relevant trace gases that play key roles in
the radiative budget of the Arctic atmosphere. Under global warming, Arctic sea ice retreats at an unprecedented rate, altering light penetration and biological communities, and potentially affect DMS and CO cycling in the Arctic Ocean. This could have socio-economic implications in and beyond the Arctic region. However, little is known about CO production pathways and emissions in this region and the future development of DMS and CO cycling. Here we summarize the current understanding and assess potential future changes of DMS and CO cycling in relation to changes in sea ice coverage, light penetration, bacterial and microalgal communities, pH and physical properties. We suggest that production of DMS and CO might increase with ice melting, increasing light availability and shifting phytoplankton community.
Among others, policy measures should facilitate large scale process studies, coordinated long term observations
and modelling efforts to improve our current understanding
of the cycling and emissions of DMS and CO in the Arctic
Ocean and of global consequences
Nitrous oxide and methane in a changing Arctic Ocean
Human activities are changing the Arctic
environment at an unprecedented rate resulting in rapid
warming, freshening, sea ice retreat and ocean acidification
of the Arctic Ocean. Trace gases such as nitrous oxide
(N2O) and methane (CH4) play important roles in both the
atmospheric reactivity and radiative budget of the Arctic
and thus have a high potential to influence the regionâs
climate. However, little is known about how these rapid
physical and chemical changes will impact the emissions of
major climate-relevant trace gases from the Arctic Ocean.
The combined consequences of these stressors present a
complex combination of environmental changes which
might impact on trace gas production and their subsequent
release to the Arctic atmosphere. Here we present our
current understanding of nitrous oxide and methane cycling
in the Arctic Ocean and its relevance for regional and
global atmosphere and climate and offer our thoughts on how this might change over the coming decades
Advances in understanding of airâsea exchange and cycling of greenhouse gases in the upper ocean
This is the final version. Available on open access from University of California Press via the DOI in this recordThe airâsea exchange and oceanic cycling of greenhouse gases (GHG), including carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), carbon monoxide (CO), and nitrogen oxides (NOx = NO + NO2), are fundamental in controlling the evolution of the Earthâs atmospheric chemistry and climate. Significant advances have been made over the last 10 years in understanding, instrumentation and methods, as well as deciphering the production and consumption pathways of GHG in the upper ocean (including the surface and subsurface ocean down to approximately 1000 m). The global ocean under current conditions is now well established as a major sink for CO2, a major source for N2O and a minor source for both CH4 and CO. The importance of the ocean as a sink or source of NOx is largely unknown so far. There are still considerable uncertainties about the processes and their major drivers controlling the distributions of N2O, CH4, CO, and NOx in the upper ocean. Without having a fundamental understanding of oceanic GHG production and consumption pathways, our knowledge about the effects of ongoing major oceanic changesâwarming, acidification, deoxygenation, and eutrophicationâon the oceanic cycling and airâsea exchange of GHG remains rudimentary at best. We suggest that only through a comprehensive, coordinated, and interdisciplinary approach that includes data collection by global observation networks as well as joint process studies can the necessary data be generated to (1) identify the relevant microbial and phytoplankton communities, (2) quantify the rates of ocean GHG production and consumption pathways, (3) comprehend their major drivers, and (4) decipher economic and cultural implications of mitigation solutions.European Space AgencyConvex Seascape SurveyEuropean Union Horizon 2020U.S. National Science Foundatio
Differing patterns of selection and geospatial genetic diversity within two leading Plasmodium vivax candidate vaccine antigens
Although Plasmodium vivax is a leading cause of malaria around the world, only a handful of vivax antigens are being studied for vaccine development. Here, we investigated genetic signatures of selection and geospatial genetic diversity of two leading vivax vaccine antigens--Plasmodium vivax merozoite surface protein 1 (pvmsp-1) and Plasmodium vivax circumsporozoite protein (pvcsp). Using scalable next-generation sequencing, we deep-sequenced amplicons of the 42 kDa region of pvmsp-1 (n = 44) and the complete gene of pvcsp (n = 47) from Cambodian isolates. These sequences were then compared with global parasite populations obtained from GenBank. Using a combination of statistical and phylogenetic methods to assess for selection and population structure, we found strong evidence of balancing selection in the 42 kDa region of pvmsp-1, which varied significantly over the length of the gene, consistent with immune-mediated selection. In pvcsp, the highly variable central repeat region also showed patterns consistent with immune selection, which were lacking outside the repeat. The patterns of selection seen in both genes differed from their P. falciparum orthologs. In addition, we found that, similar to merozoite antigens from P. falciparum malaria, genetic diversity of pvmsp-1 sequences showed no geographic clustering, while the non-merozoite antigen, pvcsp, showed strong geographic clustering. These findings suggest that while immune selection may act on both vivax vaccine candidate antigens, the geographic distribution of genetic variability differs greatly between these two genes. The selective forces driving this diversification could lead to antigen escape and vaccine failure. Better understanding the geographic distribution of genetic variability in vaccine candidate antigens will be key to designing and implementing efficacious vaccines
A tropical hotspot:Marine biogeochemistry
The ocean is an important source of the potent greenhouse gas N2O. Measurements in the tropical South Pacific have revealed a massive efflux of N2O from the coastal upwelling zone
A Harmonized Nitrous Oxide (N<sub>2</sub>O) Ocean Observation Network for the 21st Century
Chemical composition and evaluation of antinociceptive activity of the essential oil of Stevia serrata
Massive nitrous oxide emissions from the tropical South Pacific Ocean
Nitrous oxide is a potent greenhouse gas and a key compound in stratospheric ozone depletion. In the ocean, nitrous oxide is produced at intermediate depths through nitrification and denitrification, in particular at low oxygen concentrations. Although a third of natural emissions of nitrous oxide to the atmosphere originate from the ocean, considerable uncertainties in the distribution and magnitude of the emissions still exist. Here we present high-resolution surface measurements and vertical profiles of nitrous oxide that include the highest reported nitrous oxide concentrations in marine surface waters, suggesting that there is a hotspot of nitrous oxide emissions in high-productivity upwelling ecosystems along the Peruvian coast. We estimate that off Peru, the extremely high nitrous oxide supersaturations we observed drive a massive efflux of 0.2â0.9 Tg of nitrogen emitted as nitrous oxide per year, equivalent to 5â22% of previous estimates of global marine nitrous oxide emissions. Nutrient and gene abundance data suggest that coupled nitrificationâdenitrification in the upper oxygen minimum zone and transport of resulting nitrous oxide to the surface by upwelling lead to the high nitrous oxide concentrations. Our estimate of nitrous oxide emissions from the Peruvian coast surpasses values from similar, highly productive areas