Calcium alginate immobilized marine microalgae: experiments on growth and short-term heavy metal accumulation

Growth of 11 calcium alginate immobilized marine microalgal species belonging to eight taxonomical groups has been checked in the present work. Cellular densities inside the calcium alginate beads were monitored during 17 days. Good growth and maintenance of the structure of the beads were both found for some of the assayed species. One of those species (Tetraselmis chui, Prasinophyceae) was selected in order to perform a short term (up to 24 h) heavy metal accumulation experiment. Beads of calcium alginate containing (or not) cells of T. chui were exposed to 820 μg L⁻¹ Cu and 870 μg L⁻¹ Cd separately during a 24 h period, and accumulation of heavy metals in the beads was measured after this time and compared. Concentration of each metal in the supernatants was monitored at 5, 10, 60 min and 24 h from the beginning of the experiment. After 24 h, practically all Cu was removed by the beads. Beads with immobilized algae removed around 20% of total Cd, while beads without algae removed half of that percentage.     

SEEPAGE, a new MODFLOW DRAIN package

The prediction of the location of ground water discharge areas is a key aspect for the protection and (re)development of ground water-dependent wetlands. Ground water discharge areas can be simulated with MODFLOW using the DRAIN package by setting the drain level equal to the topography, while the conductance is mostly set to an arbitrary high value. However, conceptual and practical problems arise in the calculation of the ground water discharge by the DRAIN package as calculated water tables above the land surface, difficult parameterization of the conductance, and large water balance errors. To overcome these problems, a new SEEPAGE package for MODFLOW is proposed. The basic idea of this package is an adaptable constant head cell. It has a variable head, unless the ground water rises above the seepage level, in which case it has a constant head cell. The estimation of the ground water discharge location along a homogeneous, isotropic, linear sloping profile is used to verify the model and to compare it to the DRAIN solution. In an application to three basins in Belgium, it is shown that the SEEPAGE package can be used in combination with the DRAIN package in situations where an upper boundary for a free water table and additional resistance for drainage is required. It is clearly demonstrated that the identification and delineation of regional ground water discharge areas is more accurate using the SEEPAGE package.     

Deterioration Index (DI): a suggested criterion for assessing the health of coral communities

The extensive deterioration of coral reefs worldwide highlights the importance of creating efficient monitoring methods to best assess their state of health. At present, several suggested parameters serve such indicators. None of these, however, is well accepted as reliably representing reef community health. In the present study we examine a new approach based on the ratio between mortality and recruitment rates of branching corals, which we term 'Deterioration Index' (DI). It aims at providing a quantitative indication of the state of health of reef-building coral communities. The method was developed and tested on 16 coral communities on artificially laid rocks along the coast of Eilat, Red Sea (Gulf of Aqaba). In contrast to frequently used indices (i.e. mortality rate, abundance and species richness), which did not demonstrate a consistent result in comparing disturbed vs. undisturbed coral communities, the DI revealed significant differences between these communities. Our results suggest that the use of the DI may enable the detection of disturbed coral communities in one instance monitoring, where the other parameters had failed. The DI, therefore, may provide a comparable quantitative assessment of the deterioration process and its intensity in a coral community. We propose the DI approach as an efficient and applicable tool for coral reef monitoring.     

Origin of the anomalies in light and middle REE in sediments of an estuary affected by phosphogypsum wastes (south-western Spain)

Sc, Y, Th, Cu and rare earth elements (REE) concentrations have been analyzed in 14 samples of surface sediments and in two gravity cores by means of ICP-MS. Mean concentrations of Sc, Y and Th in surface sediments are 6.23, 4.76 and 16.30 ppm, respectively, lower than those present in the Upper Continental Crust (UCC). Cu concentration in these sediments is very high, 1466 ppm, and is caused by inputs from the Odiel and Tinto rivers, affected by acid mine drainage. SigmaREE mean concentration is 106.8 ppm, lower than that observed in other rivers and estuaries. In the cores, Sc, Y and Th concentrations show a significant increase in the intermediate levels, between 10 and 40 cm depth. The same pattern exists with Cu, where concentrations of 4440 ppm can be reached. Vertical evolution patterns for Sc, Y, Cu and heavy REE (HREE) are similar, and contrary to those shown by Th, light REE (LREE) and middle REE (MREE). Plots of North American Shale Composite (NASC)-normalized REE data of surface sediments show a slight depletion in REE concentrations. Most samples present with middle REE enrichment relative to light REE and heavy REE. Conversely, samples of the intermediate levels of the cores show significant enrichment of REE relative to NASC and high values in the (La/Gd)NASC and (La/Yb)NASC ratios. These anomalies in the fractionation patterns caused by enrichments in LREE and MREE concentrations is related to the presence of high concentrations of Th. They were generated by effluents from fertilizer factories between 1968 and 1998 which used phosphorite as source material.     

On deposits controlled by tectonic lenses

Tectonic lenses (e.g., boudinage structures,pinch-and-swell structures) are common geologicalstructures observed in various scales ranging fromseveral hundreds of kilometers (e.g., lenticular terranesor massifs) in orogenic belts to a few millimeters (e.g.,core-mantle structures and porphyroclasts) in petro-graphic thin-sections. The most frequently observedtectonic lenses are those developed in metamorphicrocks where compositional layers with distinctrheological strengths coexist. No matter h…     

Theoretical analyses and numerical experiments of variational assimilation for one-dimensional ocean temperature model with techniques in inverse problems

There is an international focus on the develop-ments of data assimilation systems for meteorology and physical oceanography models. Data assimilation and inverse methods are normally used for optimal control of poorly known initial boundary conditions and model parameters by taking into account both the information about dynamics of a model and the infor-mation about the true state which is constrained by a set of measurements. The research methodology of parameter estimation in meteorology ca…     

Monitoring the anthropogenic impact on the muddy coast by means of topographic and bathymetric surveys north of the Yellow River Mouth,China

1　Introduction　Manhasmodifiedmanyoftheworld’scoastlines ,eitherdirectlybyconstructionordredging ,orindi rectlyasaresultofenvironmentalchangesthatinflu encesedimentsupply ,runoff,orclimate (Johns ,1995 ) .HumanactivityhasalsoproducedthemostprofoundeffectsonthecoastalenvironmentinChina .Forex ample,damconstructions ,whichrestrictpeakflowsintheupstreamoftheYellowRiver ,couldgreatlyre ducethenaturalsupplyofsedimentintotherivermouthandresultintheerosionofbeaches .　Inrecentyears,manystudiescon…