Detoxification mechanisms in shrimp: comparative approach between hydrothermal vent fields and estuarine environments

Hydrothermal vents are extreme deep-sea habitats that, due to their singular features, still intrigue scientific communities. Swift growth rates and profuse biomass of biological communities can be observed, despite of their inherently unstable physical-chemical and toxic conditions, indicating that organisms inhabiting this environment must be well adapted to these inhospitable conditions. The caridean shrimp, Chorocaris chacei, Mirocaris fortunata and Rimicaris exoculata, together with bathymodiolid mussels, dominate the vent fauna along the Mid-Atlantic Ridge (MAR). Crustacean species are widely used as biological indicators of environmental alterations, since they play a key ecological role as planktivorous grazers, epibenthic scavengers or as prey species. The biological consequences of the hydrothermal metal-rich environment in shrimp species are still largely unknown. Therefore, the aim of this study was the determination of the metal levels (Ag, Cd, Cu, Fe, Mn and Zn), metallothioneins (MT) and lipid peroxidation (LPO) in shrimp species collected in Rainbow, Lucky Strike and Menez-Gwen vent sites, in order to evaluate their different adaptation strategies toward metals when compared with two common coastal shrimp species (Palaemon elegans and Palaemonetes varians) from a fairly unpolluted estuarine system in south Portugal (Ria Formosa). Results show significant differences in metal concentrations, MT levels and lipid peroxidation between vent and coastal shrimp and also between shrimp species from the same site. This indicates that biochemical responses in both vent and coastal shrimp are affected not only by the environmental characteristics but also by inter-specific differences. Nevertheless, these responses apparently grant a successful adaptation for the survival in a metal-extreme environment.     

Bayesian regression model for seasonal forecast of precipitation over Korea

In this paper, we apply three different Bayesian methods to the seasonal forecasting of the precipitation in a region around Korea (32.5°N?C42.5°N, 122.5°E-132.5°E). We focus on the precipitation of summer season (June?CJuly?CAugust; JJA) for the period of 1979?C2007 using the precipitation produced by the Global Data Assimilation and Prediction System (GDAPS) as predictors. Through cross-validation, we demonstrate improvement for seasonal forecast of precipitation in terms of root mean squared error (RMSE) and linear error in probability space score (LEPS). The proposed methods yield RMSE of 1.09 and LEPS of 0.31 between the predicted and observed precipitations, while the prediction using GDAPS output only produces RMSE of 1.20 and LEPS of 0.33 for CPC Merged Analyzed Precipitation (CMAP) data. For station-measured precipitation data, the RMSE and LEPS of the proposed Bayesian methods are 0.53 and 0.29, while GDAPS output is 0.66 and 0.33, respectively. The methods seem to capture the spatial pattern of the observed precipitation. The Bayesian paradigm incorporates the model uncertainty as an integral part of modeling in a natural way. We provide a probabilistic forecast integrating model uncertainty.     

Impact of coherent eddies on airborne measurements of vertical turbulent fluxes

During the Hydrological-Atmospheric Pilot Experiment (HAPEX)-Sahel, which took place in Niger in the transitional period between the wet and dry seasons, two French aircraft probed the Sahelian boundary layer to measure sensible and latent heat fluxes. The measurements over the Niamey area often revealed organised structures of a few km scale that were associated with both thermals and dry intrusions. We study the impact of these coherent structures using a single day’s aircraft-measured fluxes and a numerical simulation of that day with a mesoscale model. The numerical simulation at high horizontal resolution (250 m) contains structures that evolve from streaks in the early morning to cells by noon. This simulation shows distribution, variance and skewness similar to the observations. In particular, the numerical simulation shows dry intrusions that can penetrate deeply into the atmospheric boundary layer (ABL), and even reach the surface in some cases, which is in accordance with the observed highly negatively skewed water vapour fluctuations. Dry intrusions and thermals organised at a few km scale give skewed flux statistics and can introduce large errors in measured fluxes. We use the numerical simulation to: (i) evaluate the contribution of the organised structures to the total flux, and (ii) estimate the impact of the organised structures on the systematic and random errors resulting from the 1D sampling of the aircraft as opposed to the 2D numerical simulation estimate. We find a significant contribution by the organised structures to the total resolved fluxes. When rolls occur, and for a leg length of about 30 times the ABL depth, the 1D sampled flux is shown to be sometimes 20% lower than the corresponding 2D flux when the 1D sampling direction is the same as the main axis of the rolls, whereas the systematic error is much lower when the direction of the leg is transverse to the rolls. In the case of cells, an underestimate of around 10% can still be observed with the 1D approach independent of direction, due to poor sampling of the energy-containing scales.     

Development of an Operational Hybrid Data Assimilation System at KIAPS

This study introduces the operational data assimilation (DA) system at the Korea Institute of Atmospheric Prediction Systems (KIAPS) to the numerical weather prediction community. Its development history and performance are addressed with experimental illustrations and the authors’ previously published studies. Milestones in skill improvements include the initial operational implementation of three-dimensional variational data assimilation (3DVar), the ingestion of additional satellite observations, and changing the DA scheme to a hybrid four-dimensional ensemble-variational DA using forecasts from an ensemble based on the local ensemble transform Kalman filter (LETKF). In the hybrid system, determining the relative contribution of the ensemble-based covariance to the resultant analysis is crucial, particularly for moisture variables including a variety of horizontal scale spectra. Modifications to the humidity control variable, partial rather than full recentering of the ensemble for humidity further improves moisture analysis, and the inclusion of more radiance observations with higher-level peaking channels have significant impacts on stratosphere temperature and wind performance. Recent update of the operational hybrid DA system relative to the previous 3DVar system is described for detailed improvements with interpretation.     

Adsorption of diclofenac on activated carbon and its hypochlorination in the presence of dissolved organic matter

The nonsteroidal anti-inflammatory drug “diclofenac” is the pharmaceutically active ingredient of several medicines. Since the compound is used in many of its water-soluble salt forms, it is one of the most frequently found pollutants in different parts of the water cycle. Its reaction with sodium hypochlorite was investigated in the presence of humic substances and sandy soil extract at neutral pH at 25 and 250 mg/L initial concentrations. In the lower concentration, the reaction follows a pseudo-first-order kinetics, while at the higher concentration, it is described as the sum of two first-order reactions. These kinetic results, together with the organic chlorine content of the residues, indicated that both chlorination and oxidation took place. The chlorination is significantly faster. The colloids present catalyze the reactions: The clay minerals of soil extract accelerated the chlorination, while the humic acids could work as photocatalysts in the oxidation, while these compounds themselves were chlorinated. The adsorption of diclofenac on activated carbon was enhanced by humic substances, and every isotherm had a breaking point near to 3 mg/L equilibrium concentration (c _e) resulting in two steps. According to the measurements of the zeta potential, the system proved to be relatively stable at this c _e value, but at higher diclofenac concentrations the stability retained only in the presence of the hydrophilic fulvic acid. The results supported the adsorption hypothesis that in the first step the charge transfer interaction while in the second step hydrogen bond formation plays the key role.     

Liquid content of the lower clouds of venus as determined from mariner 10 radio occultation

S-band (13.06-cm) and X-band (3.56-cm) radio occulation data obtained during the flyby of Venus by Mariner 10 on February 5, 1974 were analyzed to obtain the effects of dispersive microwave absorption by the clouds of Venus. The received power profiles were first corrected for the effects of refraction in the atmosphere of Venus, programmed changes in the pointing direction of the high-gain antenna, and limit-cycle motion of the spacecraft attitude control system. The resulting excess attenuation profiles presumbaly due to cloud absorption have been inverted discretely to obtain profiles of absorption coefficient at the two wavelenghts. The ratios of the absorptivities are consistent with a sulfuric acid-water mixture as the constituent of the absorbing clouds, having a sulfuric acid concentration of 75 ± 25%. Three absorption peaks are evident in the profiles at altitudes of 68, 60, and 48 km. With a sulfuric acid concentration of 75%, the upper cloud has a peak liquid content of 0.08 g/m³, and an integrated content of 0.024 g/cm², which corresponds roughly to terrestrial stratus or altostratus clouds. The major absorption layer has a peak of 1.1 g/m³ at an altitude of 48 km, with an integrated content of 0.5 g/cm², similar to that of terrestrial cumulus and cumulonimbus clouds. The absorption ratios for the middle cloud at 60 km are not consistent with a sulfuric acid-water mixture.     

Nekton use of salt marsh creeks in the upper Tejo estuary

The use of the Tejo estuary, Portugal, salt marsh creeks by nekton was examined based on sampling surveys with a fyke net from September 1998 until August 2001. From the 20 taxa (14 fish species, 5 decapod crustacean species, and 1 cephalopod species) identified in the studied creeks, 16 were regularly caught throughout the sampling period. The shrimpPalaemonetes varians was the most numerically abundant species in the creeks, while the biomass was dominated by the mulletLiza ramada. The nekton assemblage was mainly represented by marine-estuarine opportunist species, comprising 85% of the total. A high seasonality was detected on the species abundance patterns: the most abundant species (P. varians, Crangon crangon, L. ramada, Pomatoschistus microps, Syngnathus sp., andAnguilla anguilla) occurred throughout the sampling period,Sardina pilchardus, Dicentrarchus, labrax, andAtherina boyeri were particularly abundant in spring and summer, andEngraulis encrasicholus, Liza aurata, Gambusia holbrooki, Palaemon longirostris, andPalaemon serratus were most abundant in autumn and winter.L. ramada occurred in the tidal creeks in high numbers during neap tides, while the majority of the remaining taxa were most abundant during spring tides, suggesting a differential pattern of habitat use occording to species.     

Geological and Geotechnical Characteristics of Marine Clays at the Busan New Port

Despite a number of geotechnical investigations that have been carried out in the Busan new port area of South Korea, the local practicing engineers have been unable to deduce successfully the geotechnical properties of the clays due to their spatial variation. In the area, clay deposits, so-called Pusan clays, are unusually thick, varying from 20 m to 70 m in thickness. For this study, comprehensive geological and geotechnical investigations were carried out with sophisticated sampling techniques, in situ and laboratory tests as well as geological analyses at an additional three locations. As a result of the investigations, it was found that depositional environments are closely related to the relative changes in sea level and have different features depending on location and depth. The clays consist of soft and stiff clays in the upper and the lower layers, respectively, which are classified as normally consolidated and cemented clay. Moreover, most of the geotechnical properties undergo small changes due to their depositional environment. Information about these effects would be quite helpful to understand the spatial variation of geotechnical properties as well as the effect of sample disturbance. Some correlations which reflect the geological history of the deposts were conducted for physical indexes and mechanical properties.