Sub-surface precipitation of salts in supercritical seawater

Extremely low solubility of typical seawater salts within certain supercritical sections of their pressure–temperature composition space is a proven experimental fact. Its consequences are often referred to as either 'shock crystallization' or 'out-salting'. Our alternative model for the formation of salt deposits hypothesizes that high temperatures and pressures characteristic for the high heat-flow zones of tectonically active basins may bring submarine brines into the out-salting regions and result in the accumulation of geological-scale salt depositions.
To confirm the laboratory observations, molecular-scale simulations (molecular dynamics) have been employed to study structural changes in a model seawater system where temperature increased from ambient to near-critical and supercritical. Fluid properties and phase transition regions extracted from the simulations were then used as input parameters for a reservoir simulator program to model out-salting in a simple hydrothermal geological system. Both numerical simulations and laboratory experiments confirm that supercritical out-salting is a viable process of geological significance for the formation and accumulation of evaporites. We suggest two regions where hydrothermally associated salts may be depositing today: Atlantis II Deep, in the Red Sea, and Lake Asale, Ethiopia.     

Bacterial community succession in response to dissolved organic matter released from live jellyfish

Jellyfish blooms have increased worldwide,and the outbreaks of jellyfish population not only affect the food web structures via voracious predation but also play an important role in the dynamics of nutrients and oxygen in planktonic food webs.However,it remains unclear whether specific carbon compounds released through j ellyfish metabolic processes have the potential to shape bacterial community composition.Therefore,in this study,we aimed to investigate the compositional succession of the bacterioplankton community in response to the dissolved organic matter(DOM)released by the live Scyphomedusae Cyanea lamarcki'i and Chrysaora hysoscella collected from Helgoland Roads of the North Sea.The bacterial community was significantly stimulated by the DOM released form live jellyfish and different dominant phylotypes were observed for these two Scyphomedusae species.Furthermore,the bacterial community structures in the different DOM sources,jellyfish-incubated media,Kabeltonne seawater,and artificial seawater(DOM-free)were significantly different,as revealed by automated ribosomal intergenic spacer analy sis fingerprints.Catalyzed reporter depo sition fluorescence in situ hybridization(CARD-FISH)revealed a rapid species-specific shift in bacterial community composition.Gammaproteobacteria dominated the community instead of the Bacteroidetes community for C.lamarckii,whereas Gammaproteobacteria and Bacteroidetes dominated the community for C.hysoscella.The significant differences in the bacterial community composition and succession indicate that the components of the DOM released by jellyfish might differ with jellyfish species.     

Map Comparison or Traditional Mass-balance Measurements: Which Method is Better?

A number of Norwegian glaciers were selected in the 1960s for long-term mass-balance measurements, to produce necessary hydrological information for hydropower exploitation. Special large-scale glacier maps were produced for field work and data processing, and some glaciers have been mapped more than once. Thus, comparison of glacier maps can be used to calculate changes in glacier volume for some of the glaciers, provided they are of sufficient accuracy.
Conventional mass-balance measurements were carried out on all the selected glaciers. A cumulative calculation of net balances for a series of years is used to indicate the change in a glacier's volume during that period. However, various errors originate in the field, some of which are systematic, particularly on glaciers with large winter accumulation.
The present study indicates that certain errors are difficult to define and determine, For the maritime glacier Ålfotbreen, a cumulative mass-balance calculation gives a positive total balance (+3.4 m water equivalent in the period 1968–88), whereas the map comparison indicates a total negative balance (−5.8 m water equivalent). This indicates a discrepancy between the methods, which must be accounted for.
Determination of errors in mass-balance measurements is difficult. Sinking of stakes in the accumulation area and the use of sounding sticks (steel probes) in heavy snowlayers cause problems.     

How will climate change alter fishery governanceʔ Insights from seven international case studies

We examine the implications of climate change for fishery governance using seven international fishery case studies in low, mid and high latitudes, including eastern Australia, the western Pacific Ocean, Alaska, west coast United States, Hawaii, west coast Canada and France. Climate change adds uncertainty about fish stock productivity, migratory patterns, trophic interactions and vulnerability of fish populations to fishing pressure.     

Weakening AMOC connects Equatorial Atlantic and Pacific interannual variability

Observations indicate that since the 1970s Equatorial Atlantic sea surface temperature (SST) variations in boreal summer tend to modulate El Niño in the following seasons, indicating that the Atlantic Ocean can have importance for predicting the El Niño–Southern Oscillation (ENSO). The cause of the change in the recent decades remains unknown. Here we show that in the Bergen Climate Model (BCM), a freshwater forced weakening of the Atlantic meridional overturning circulation (AMOC) results in a strengthening of the relation between the Atlantic and the Pacific similar to that observed since the 1970s. During the weakening AMOC phase, SST and precipitation increase in the central Equatorial Atlantic, while the mean state of the Pacific does not change significantly. In the Equatorial Atlantic the SST variability has also increased, with a peak in variability in boreal summer. In addition, the characteristic timescales of ENSO variability is shifted towards higher frequencies. The BCM version used here is flux-adjusted, and hence Atlantic variability is realistic in contrast to in many other models. These results indicate that in the BCM a weakening AMOC can change the mean background state of the Tropical Atlantic surface conditions, enhancing Equatorial Atlantic variability, and resulting in a stronger relationship between the Tropical Atlantic and Pacific Oceans. This in turn alters the variability in the Pacific.     

CO2 equivalences for short-lived climate forcers

With advancing climate change there is a growing need to include short-lived climate forcings in cost-efficient mitigation strategies to achieve international climate policy targets. Tools are required to compare the climate impact of perturbations with distinctively different atmospheric lifetimes and atmospheric properties. We present a generic approach for relating the climate effect of short-lived climate forcers (SLCF) to that of CO₂ emissions. We distinguish between three alternative types of metric-based factors that can be used to derive CO₂ equivalences for SLCF: based on forcing, activity and fossil fuel consumption. We derive numerical values for a wide range of parameter assumptions and apply the resulting generalised approach to the practical example of aviation-induced cloudiness. The evaluation of CO₂ equivalences for SLCF tends to be more sensitive to SLCF specific physical uncertainties and the normative choice of a discount rate than to the choice of a physical or economic metric approach. The ability of physical metrics to approximate economic-based metrics alters with changing atmospheric concentration levels and trends. Under reference conditions, physical CO₂ equivalences for SLCF provide sufficient proxies for economic ones. The latter, however, allow detailed insight into structural uncertainties. They provide CO₂ equivalences for SLCF in short term strategies in the face of failing climate policies, and a temporal evolution of CO₂ equivalences over time that is noticeably better in line with cost-efficient climate stabilisation.     

Effects of virus infection on expression of cell cycle regulatory proteins in the unicellular marine algae Emiliania huxleyi

The authors have investigated the biochemical events by which marine algal virus infection induces cell cycle arrest. The key G₂/M-phase regulatory proteins are analyzed by immunobloting in unicellular Emiliania huxleyi, suggesting that virus induced cell cycle arrest is related with virus''s effect on cyclins and cyclin dependent kinases. E. huxleyi virus (EhV) represses Cdc2/cyclinB complex activity by inhibiting the activity of Cdc2 kinase in a phosphorylation-related manner, blocking host cells G₂/M checkpoint. Dephosphorylated/inactive Cdc25C combined with up-regulation of Wee1 expression at early infect period appears to be important mechanisms by which EhV represses Cdc2/cyclinB complex activity that is required for entry into M phase. This study has allowed us to confirm that algal virus infection leads to selective activation or inhibition of certain cell-cycle factors, which may play a significant role in establishing a more efficient environment for viral gene expression and DNA replication.