Onset of the Iberian upwelling along the Galician coast

Through a set of observations including satellite, cruise and mooring data during May-July 1997 the transition between the downwelling and upwelling regimes off Galicia has been characterized. The poleward flow, typical of downwelling, was associated with a series of mesoscale eddies and interacted with coastal freshwater inputs. The poleward flow along the continental slope was separated into an offshore branch and a nearshore branch by a well-defined equatorward flow and both associated with a prominent salinity maximum. With the onset of upwelling-favorable winds, equatorward flow was established over the entire shelf. At the same time, a buoyant, warm surface layer spread out over the shelf from the Rías as water previously forced in by southerly winds was flushed out by the upwelling winds. The completed transition to summertime coastal upwelling took place after the cruise but was evident in satellite images. A conceptual model is used to demonstrate that the coastal orientation with respect to the upwelling winds enhances offshore flow outside the Rías and displaces the poleward flow offshore after several days of upwelling.     

Precipitation of carbonates by bacteria isolated from wastewater samples collected in a conventional wastewater treatment plant

This research studied the precipitation of calcium carbonate by populations of bacteria from domestic wastewater cultivated in both natural and artificial solid culture media. The only carbonate-forming bacteria detected appeared in an artificial medium added with calcium acetate. Precipitation occurred three days after inoculation, and the percentage was slightly higher than 65 %. Our results showed that nine major carbonate-forming colony types were the dominant heterotrophic platable bacteria growing aerobically in artificial media added with calcium acetate. According to their taxonomic affiliations (based on partial sequencing of the 16S-rRNA), the nine strains belonged to the following nine genera of Gram-negative and Gram-positive bacteria: Caulobacter, Blastomonas, Roseobacter, Staphylococcus, Bacillus, Gemmatimonas, Saccharopolyspora, Microthrix, and Sphingomonas. All of these strains formed calcium carbonate, precipitated as calcite and vaterite in different proportions and shapes (spheres, hemispheres, dumbbells, and pseudopolyhedral forms). The results of this study suggest that in real domestic wastewater, the precipitation of carbonates through bacterial action could not take place in situ because the concentrations of calcium did not create the optimal circumstances for biomineralization. However, in the artificial media, it was possible to induce this process by adding calcium ions.     

Ra and Rn isotopes as natural tracers of submarine groundwater discharge in the patagonian coastal zone (Argentina): an initial assessment

Submarine groundwater discharge (SGD) is herein recognized as a significant pathway of material transport from land to the coastal SW Atlantic Ocean and thus, it can be a relevant factor affecting the marine biogeochemical cycles in the region. This paper focuses on the initial measurements of ²²⁶Ra, ²²⁸Ra and ²²²Rn made in Patagonia’s coastal zone of Chubut and Santa Cruz provinces (42°S–48°S, Argentina). ²²⁶Ra activity ranged from 2.9 to 73.5 dpm 100 L^?1, and ²²⁸Ra activity ranged from 11.9 to 311.0 dpm 100 L^?1 in groundwater wells. The radium activities found in Patagonia’s marine coastal regions and adjacent shelf indicate significant enrichment throughout the coastal waters. Groundwater samples presented the largest ²²²Rn activity and ranged from 2.66 to 1083 dpm L^?1. Conversely, in the coastal marine environment, the ²²²Rn activity ranged from 1.03 to 6.23 dpm L^?1. The Patagonian coastal aquifer showed a larger enrichment in ²²⁸Ra than in ²²⁶Ra, which is a typical feature for sites where SGD is dominant, probably playing a significant role in the biogeochemistry of these coastal waters.     

Climate change hotspots over South America: from CMIP3 to CMIP5 multi-model datasets

This study identifies possible hotspots of climate change in South America through an examination of the spatial pattern of the Regional Climate Change Index (RCCI) over the region by the end of the twenty-first century. The RCCI is a qualitative index that can synthesize a large number of climate model projections, and it is suitable for identifying those regions where climate change could be more pronounced in a warmer climate. The reliability and uncertainties of the results are evaluated by using numerous state-of-the-art general circulation models (GCMs) and forcing scenarios from the Coupled Model Intercomparison Project phases 3 and 5. The results show that southern Amazonia and the central-western region and western portion of Minas Gerais state in Brazil are persistent climate change hotspots through different forcing scenarios and GCM datasets. In general, as the scenarios vary from low- to high-level forcing, the area of high values of RCCI increase and the magnitude intensify from central-western and southeast Brazil to northwest South America. In general, the climatic hotspots identified in this study are characterized by an increase of mean surface air temperature, mainly in the austral winter; by an increase of interannual temperature variability, predominantly in the austral summer; and by a change in the mean and interannual variability of precipitation during the austral winter.     

Effects of Geomorphology on the Distribution of Metal Abundance in Salt Marsh Sediment

The purpose of this study is to investigate the effects of salt marsh geomorphology on the distribution of surface metal content. Surface sediment samples (46) were taken along two transects across an intertidal salt marsh island. Abundance of Ca, Al, Fe, Ni, Cr, Cu, Zn, Rb, Sr, As, and Zr vary up to 300?% with statistically significant differences along transects and between transects. Along transect, metal abundances are strongly influenced by elevation and distance from the subtidal channel. Between transects, salt marsh morphodynamics, relative marsh age, and water sources seem to affect metal distribution. These observations lead us to hypothesize that at least three scales of variability can be expected for assessing salt marsh sediment metal distributions. Larger-scale variations associated with salt marsh sediment sources and age, and another related to local salt marsh geomorphic structure. Therefore, studies that characterize salt marsh metal loading should explicitly consider the variability imposed over a range of spatial scales.     

Geoarchaeology and Construction of the La Chabola de la Hechicera Megalithic Tomb,Elvillar, Northern Spain

La Chabola de la Hechicera, a Neolithic collective tomb which was first used at ca. 3850 B.C., has been re‐excavated for interpretation and stabilization. Information about the sources, handling, and placement of building materials allowed determination of the methods used to construct the dolmen monument. All of the rocks used in the structure are local Miocene sandstones, and the slabs were probably taken directly from the base of natural slopes near the monument. The chamber slabs were not carved, but some passage slabs were retouched to level the cover slabs. Fragments for the tumulus were obtained by mechanical fracturing. All of the slabs are imbricated, making it possible to determine the order in which they were placed. Thus, the identification of building materials and their mode of placement allows for the reconstruction of each stage of the building of the monument, providing unusually rich data for understanding the geoarchaeology and building archaeology of a dolmenic structure.     

Development of MINISAT 01 Scientific Payload

The MINISAT design is a modular concept, and accordingly the ScientificPayload of Mission 01 is a self-contained Payload Module (PLM). Thisphilosophy offers the advantage that the Payload and the Platform may beassembled independently and coupled together at a later stage. Themechanical, thermal, power and data interfaces have to be secured alongthe design and development phases. The MINISAT 01 PLM with threeinstruments, EURD, LEGRI and CPLM, integrates on a structural tray adozen of equipment supplied by more than ten participant Institutions. TheAssembly, Integration and Verifications (AIV) of the PLM, was performedat INTA, providing the common structural, harnessing and thermal controlsubsystems. In this paper an overview is presented of the PLM layout of thedifferent models and the qualification and acceptance testing.     

用孔隙水中氯离子浓度异常估算天然气水合物含量

水分子与烃类气体沉积物孔隙中结合形成水合物的过程中,只吸取孔隙中的淡水,而盐类物质不能进入水合物的晶体结构,在水合物形成过程中会引起局部孔隙水离子浓度的浓缩,增加周围沉积物孔隙水的盐度;而当水合物分解时,孔隙水就会被稀释,使得钻孔获得的水合物样品比不含水合物的样品具有更低的盐度.因为C1-是浅层海洋没积物孔隙水中一种丰富且保守的离子,C1-离子浓度变化通常被用来监测天然气水合物的形成和分解.……     

The Chemical Nature of Phosphorus in Subtropical Lake Sediments

The phosphorus (P) composition of sediment profiles in three subtropical lakes of contrasting trophic state in Florida, USA, was determined by sequential fractionation and solution ³¹P NMR spectroscopy. Sediment from Lake Annie, an oligo-mesotrophic sinkhole with moderately acidic sediment (pH 5.4; loss on ignition 58 %), contained higher total P concentrations than sediment from eutrophic Lake Okeechobee (pH 7.7, loss on ignition 36 %) and hyper-eutrophic Lake Apopka (pH 7.5, loss on ignition 69 %). The chemical nature of sediment P varied markedly among the three lakes, suggesting the predominance of different diagenetic processes. Lake Okeechobee sediment was dominated by inorganic P, indicating the dominance of abiotic reactions; Lake Annie sediment contained abundant organic P throughout the sediment profile, indicating the importance of organic P stabilization at acidic pH; Lake Apopka contained almost half of its sediment P in microbial biomass, indicating the importance of biotic processes in regulating P dynamics. Solution ³¹P NMR spectroscopy of NaOH–EDTA extracts revealed that organic P occurred mainly as phosphomonoesters in all lakes. However, sediment from Lake Apopka also contained abundant phosphodiesters and was the only lake to contain detectable concentrations of polyphosphate, perhaps due to a combination of alternating redox conditions and high concentrations of inorganic phosphate and organic carbon. Organic P concentrations determined by sequential fractionation and solution ³¹P NMR spectroscopy were similar for all lakes when microbial P was included in values for sequential fractionation. We conclude that the chemical nature of sediment P varies markedly depending on trophic state and can provide important information on the dominant processes controlling P cycling in subtropical lakes.