About 70 fossil and live-collected specimens of Desmophyllum dianthus were collected from steep rocky surfaces and time-averaged assemblages at their base ("coral graveyards") in the southern Labrador Sea at depths ranging from similar to 1700 m (Orphan Knoll) to similar to 2200 m (Flemish Cap). Aside from stable isotope and mineralogical analysis, U-series and C-14 age determinations were performed on the samples. Fossil corals from the coral graveyards display two principal age clusters corresponding respectively to the Holocene and Marine Isotope Stage (MIS) 5c intervals. Three samples lay outside these clusters, at similar to 13.5 ka (Bolling-Allerod), similar to 64 ka (MIS 3) and at similar to 181 ka (MIS 7a). The clusters are thought to record intervals with both i) high food availability, either through pelagic primary production in the overlying water column or more effectively in relation with particulate and dissolved organic carbon transport via an active Western Boundary Undercurrent (WBUC), and ii) high carbonate micrite advection by this current from more open North Atlantic coccolithophorid production areas, maintaining an aragonite saturation horizon (now at 2300 m) slightly deeper than the coral habitat (similar to 2200 m). Attempts at estimating ventilation ages from Th-230 vs C-14 age offsets in Holocene samples failed. This is due to uncertainties about the initial C-14-apparentage of coral skeletons and to their high initial excesses in Th-230. This initial excess relates mostly to the scavenging of Th-230 produced by the dissolved marine U by the coral-feeding organic matter carried along the WBUC trajectory. In addition, discrete diagenetic U-fluxes can be documented in fossil samples. They are well illustrated in specimens from MIS 5c age, which depict variable excesses in U-234 VS U-238, but similar Th-230/U-238 activity ratios, pointing to a recent but fractionating redistribution of uranium in the samples. These are also documented by the development of Fe-Mn coatings of specimens exposed at the sea floor, due to the winnowing of embedding slope sediments, with the mid- to late Holocene intensified WBUC. Such diagenetic processes are to be notably taken into consideration for the dating of pre-Holocene samples. Thus, both the initial isotopic properties of corals from this WBUC-influenced, mid-continental slope, and subsequent diagenetic effects impact their calculated ages, and blur estimates of "ventilation ages" based on their C-14 vs Th-230-ages offsets.

Sea level rise, one of the most evident effects of recent climate change, is already impacting coastal ecosystems. Because of its low relief, population increase and economic development during the last century, the Celestun lagoon is highly vulnerable to global change, including sea level rise. Here, we study a sediment core from a tropical saltmarsh to evaluate the impact of sea level rise on sediment accretion and carbon fluxes. Some geochemical indicators in a 210Pb dated sediment core showed clear signals of marine influence. This was reflected on increased accretion rates, from 0.3 ± 0.1 mm yr− 1 in ≈ 1941 to 2.9 ± 1.2 mm yr− 1 in 2012. These accretion rates were similar to eustatic sea level rise, and mean acceleration ranged from 0.037–0.22 mm yr− 2, implying a SLR by 2100 ranging from 14 to 86 cm. The one-century (1917–2013) organic carbon stock in sediments was calculated to be 10.1 ± 0.2 Mg C ha− 1. During the same period, the organic carbon flux, corrected for organic carbon degradation, increased from 7 ± 3 g C m− 2 yr− 1 to 73 ± 26 g C m− 2 yr− 1, attributed to the impact of sea level rise in this ecosystem. This work shows that tropical saltmarshes may provide useful information on sea level rise, and the presented methodology may be used where instrumental records do not exist or they are too short.

Two lead-210 (210Pb) dated sediment cores from Chapala Lake were studied to identify the mineral composition of the sediments and to discuss its relation with trace metals. Minerals and trace metals reflected the domain of volcanic rocks (i.e. basalts, rhyolite and andesite) that characterize Chapala Lake and the Lerma River watershed. Redundancy analyses (RDA) were used to identify the sedimentary variables (magnetic susceptibility, organic matter, sand content, and mineral composition) that could be related to elemental composition. Despite the distance between the two cores (7.3km) and hydrodynamic circulation the RDA showed that the main mechanism that controls the input of mineral species, and, therefore, element distributions in the lacustrine sediment of Chapala Lake, is related to the weathering of volcanic rocks in the Lerma-Chapala watershed, the consequent runoff and transport of fine grained catchment materials, and later in-lake processes. These findings highlight the importance of controlling watershed erosion to contribute to the improvement of the environmental quality of the lake.

The accumulation, enrichment and provenance of selected trace metals (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, V and Zn) were studied in sediment cores collected from three lakes located in the Central Mexican Plateau, selected on the basis of their contrasting degree of urbanization: Santa Elena Lake, in a rural and remote area; El Tule Lake, in a rural and slightly urbanized area; and Chapala Lake, in a highly urbanized area. Grain size, magnetic susceptibility and sedimentary constituents such as organic carbon, calcium carbonate, as well as major (Al, Fe, Mn) and minor (Ca, Li, Rb, Sr, Th) elements were analyzed to explain the concentration trends of trace metals. Factor analysis (FA) was used to assess the provenance of the trace elements. The highest metal enrichment factor (EF) above natural concentration levels was found at Chapala Lake for Ag (EF = 3.9), although other trace element EF in all lakes was < 2.0, indicating slight contamination. However, the concentration levels of Cr and Ni in all lakes, Hg and Zn in Chapala Lake, Cu in El Tule Lake and As in Santa Elena Lake were above international benchmarks for which adverse effects are expected to occur frequently, even for those metals only slightly enriched (e.g. As, Cr). Through FA, the terrigenous contribution was identified as the most important source of trace metals to the three lakes, most likely related to deforestation and erosion of the surrounding areas, followed by atmospheric transport of volcanic ashes, rather than to direct sources.

Paleomagnetic inclination, declination and relative paleointensity were reconstructed from the sediments of Laguna Potrok Aike in the framework of the International Continental scientific Drilling Program (ICDP) Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO). Here we present the u-channel-based full vector paleomagnetic field reconstruction since 51.2 ka cal BP. The relative paleointensity proxy (RPI) was built by normalising the natural remanent magnetisation with the anhysteretic remanent magnetisation using the average ratio at 4 demagnetisation steps part of the ChRM interval (NRM/ARM(10-40) (mT)). A grain size influence on the RPI was removed using a correction based on the linear relationship between the RPI and the median destructive field of the natural remanent magnetisation (MDFNRM). The new record is compared with other lacustrine and marine records and stacks from the mid- to high-latitudes of the Southern Hemisphere, revealing consistent millennial-scale variability, the identification of the Laschamp and possibly the Mono Lake geomagnetic excursions, and a direction swing possibly associated to the Hilina Pali excursion at 20 ka cal BP. Nonetheless, a global-scale comparison with other high-resolution records located on the opposite side of the Earth and with various dipole field references hint at a different behaviour of the geomagnetic field around southern South America at 46 ka cal BP. (c) 2012 Elsevier Ltd. All rights reserved.

The Isthmus of Tehuantepec corresponds to the shortest distance (~200 km) between the Gulf of Mexico and the Pacific Ocean in Southern Mexico, and the main economical activity of this region is oil extraction and refining. Polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs) were determined in a 210Pb dated sediment core collected from the continental shelf of Tehuantepec Gulf, in the vicinity of the oil refinery of Salina Cruz, Oaxaca, the main oil refining facility of the country. The sediments were mostly of coarse nature and hence PAHs and TPHs concentrations throughout the core (61–404 μg g−1 and 29–154 mg kg−1, respectively) were below international quality benchmarks. Depth profiles of both PAHs and TPHs concentrations showed increasing trends since the early 1900s but the higher values were found from the 1950s to present. PAH congener ratios showed that these contaminants had both petrogenic and pyrolitic sources, although the former has been predominant since the 1970s. The Salina Cruz refinery started operations in 1978 but the oil industry activities in the Tehuantepec Isthmus go back to the beginning of the twentieth century with the operation of Minatitlan refinery in the Gulf of Mexico, and the Gulf of Tehuantepec being the main conduit for oil distribution in the Pacific coast. The observed changes in contaminant distributions described well the oil industry development in the area.

Coastal ecosystems are subject to many anthropogenic pressures, including pollution and the enhancement of sedimentation due to human activities. The lower reach of the Coatzacoalcos River is considered to be the most polluted coastal area of Mexico due to the presence of major petrochemical production centers in its watershed. In order to show the impact of land use change and industrial activities on the adjacent coastal environment of the Coatzacoalcos River, we reconstructed the historical changes of sediment transport and trace metals contamination based on the study of a 210Pb dated sediment core. Several geochemical indicators, such as clay mineral content, the concentrations of reference elements (Al, Ca, Sr, Rb) and the carbon isotope ratio (δ13C) revealed a change of sediment and contamination sources since the early 80s, in coincidence with the large industrial and urban development in the area. We conclude that the increased contaminant loads were related to terrestrial sources, likely contaminated and eroded soils from the catchment, due to extensive land use changes. Although the contaminant enrichment since the early 80s was low, As, Hg and Ni concentrations show potentially dangerous levels and exceed the USEPA-ERL concentration benchmarks, thus constituting a potential threat to marine aquatic life and humans through seafood consumption.

The elevation and timing of high sea stands during Oxygen Isotope Stage (OIS) 7 are not as well constrained as those of OIS 5e. Conflicting values are reported from Mediterranean coastlines, and fossil dating is inaccurate because Of ubiquitous open U-series systems. New morphostratigraphic data from La Marina (eastern Spain) supported by open-system U-series coral ages shed light on the maximum sea level during OIS 7. Fossil corals (Cladocora caespitosa) underlying an OIS 5e marine unit yielded U-series ages from 178 +/- 10 to 208 +/- 11 ka (+/- 2 sigma; n = 7) with an outlier at 240 +/- 18 ka. Mean open-system limit ages of 170 +/- 10 (minimum age after correction for Th-234-Th-230 uptake) and 237 +/- 20 ka (maximum age after correction for U-238-U-234 uptake) were calculated to have a probable age closer to the minimum value, for an assignment of OIS 7a or 7c. The occurrence of a warm-water "Senegalese" fauna (Strombus bubonius) in OIS5e and OIS 7 marine units confirms the arrival of tropical species to the Mediterranean before the last interglacial period. Morpho-sedimentological and neotectonic studies suggest that the maximum paleo-sea level during OIS 7c or 7a was a few meters below that of OIS 5e. (c) 2006 Lavoisier SAS. All rights reserved.

A sedimentary sequence from the Espejo de los Lirios lake in the Metropolitan Zone of Mexico City (MZMC) was analyzed in detail for 210Pb and 137Cs activities, allowing to assess the evolution of the accretion rates in the lake during the last ∼84±4 years. The core revealed the deposition of contemporaneously indigenous lake sediments to the site interspersed with eroded bedrock from the catchment, evidencing episodic increases in sediment accretion which varied from 0.14 to 0.93 cm year−1. Increasing trends in sedimentation rates were found to be closely related to demographic expansion of the Metropolitan Zone of Mexico City and explained on the basis of the erosive processes produced as a result of deforestation created as a consequence of the urban and industrial development of the MZMC.

The accumulation of selected trace metals (Ag, Cd, Co, Cr, Cu, Hg, Ni, Pb, V and Zn) was studied in a sediment core collected at Espejo de los Lirios lake, a precipitation-dominated seepage lake in Northern Mexico City Metropolitan Zone (MCMZ). A (210)Pb-derived chronology, obtained from the same core, was used to reconstruct the historical metal fluxes at the site, allowing evaluation of the impact of environmental changes promoted by the development of the City during the last approximately 125 years. The highest levels of metal enrichment above natural concentration levels (NCL) in the sediments from Espejo de los Lirios lake were found for Ag and Pb (approximately 250%) as well as a slight enrichment for Cd (55%), Cr (84%), Co (20%), Cu (60%), Hg (47%), Ni (45%), V (59%) and Zn (66%). Fluxes of trace metals appeared to have noticeably increased from the last 45 years showing the maximum increments for Cd, Co, Cr, Ni, V and Zn during the 1980's (9 to 13 fold natural fluxes), for Ag and Cu (17 and 12 fold, respectively) during the 1990's and for Hg and Pb (2 and 13 fold) during the middle 1970's. Low levels of metal enrichment observed have evidenced that the most conspicuous consequences of the expansive growth of this area of the MCMZ, are mostly related to deforestation and erosion of the surrounding areas, rather than to trace metal pollution. Based on PCA, it can be assumed that atmospheric deposition, weathering of bedrock and soil within the watershed and authigenic production, are the most important processes that explain the trace metal distribution in the site.

Purpose. To compare the physical and physicochemical characteristics of carbamazepine microparticles prepared using two different methods: (1) the rapid expansion of supercritical solutions (RESS) and (2) the spray-drying process. Methods. For both processes, microparticles were produced over a range of different temperatures (35 to 100°C). For the RESS method, carbon dioxide was the solvent used over a pressure range of 2500 to 3500 psi. As for the spray-drying method, different organic solvents were used at atmospheric pressure. Comparison was based on morphology, crystalline structure, mean particle size, and size distribution of processed particles. The influence of process parameters on microparticles' characteristics was also investigated. Particles were analyzed using scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), thermogravimetric analyzer (TGA), and differential scanning calorimetry (DSC). Results. The carbamazepine particles used as unprocessed starting material had a mean diameter of approximately 85 μm with a size distribution range between 15 and 336 μm. Microparticles produced by either the RESS or spray-drying method had a mean diameter smaller than 2 μm and a narrower size distribution range between 0.25 and 2.5 μm. SEM photomicrographs, X-ray diffractograms, and DSC spectra revealed that modification of crystal morphology was dependent on the operating conditions. Conclusions. Significant reduction in mean particle size and size distribution range of carbamazepine particles was observed by RESS and spray-drying methods. The results also demonstrate that the crystalline nature of carbamazepine particles depends on the method of production and on the operating parameters of pressure and temperature.

Carbamazepine microparticles were produced by the rapid expansion of supercritical carbon dioxide solutions (RESS) method. The characteristics of the resulting particles were studied by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and image analysis. X-ray diffractograms and SEM photomicrographs revealed that the crystalline nature of the produced carbamazepine microparticles depended on operating pressure and temperature conditions. Different polymorphs were obtained under various operating conditions. Under certain temperature (below 40 °C) and pressure (below 240 bar) conditions, it was possible to form primarily the carbamazepine polymorph stipulated by US Pharmacopeia. A significant reduction was observed in the particle size and size distribution range of carbamazepine produced by RESS. The processed particles had a mean diameter smaller than 3 μm and a size distribution range between 0.5 and 2.5 μm compared to unprocessed starting material with a mean diameter of approximately 85 μm and a size distribution range between 15 and 336 μm. Thus, this study demonstrates that the polymorphic characteristics of carbamazepine microparticles produced by the RESS method can be controlled by varying operating pressure and temperature parameters.

When characterizing multi-phase materials, several authors have recommended separating the material into various fractions consisting of a reduced number of minerals. However, the common separation techniques are of limited value when treating ultra-fine-grained materials. We present in this paper a separation technique using tensio-active solutions which break up any particle agglomerates which may be present and facilitates sedimentation of component particles according to grain size. These fractions have a distinctive mineralogy and chemistry. The technique has been applied to two selected samples from two mining residue sites in Germany. Results from Bielatal, a tin residue, show that a large proportion of the arsenic and heavy metals are concentrated in a suspension fraction, which consists of clay minerals and amorphous iron oxyhydroxides. Silicates such as a micas and feldspar settle out quite rapidly, whereas, other minerals, such as hematite take longer. In the case of Dänkritz, a uranium mine waste, the same technique was applied and similar results were obtained for the heavy metals distribution. Additional study indicated that radium is with barite and other radio-isotopes were associated with the fine suspension fraction.

Cross-linked high-amylose starch (CLHAS), obtained by high-amylose starch cross-linking, was recently introduced as an excipient (Contramid™) for monolithic dosage forms that are able to control drug release over 18–24 h. These control properties are related to tablet swelling and are strongly dependent on the degree of the cross-linking of CLHAS. The permeability of solutes through CLHAS hydrogels depends on the chemical structure of the polymer. The aim of this study was to obtain a better understanding of how modifications in CLHAS molecular structures at the level of long-range and short-range order during the cross-linking and processing conditions relate to the release properties of the CLHAS matrices. Structural parameters such as crystallinity contribute significantly to the physical and mechanical aspects of starch products. X-ray diffractometry, FTIR spectroscopy, dissolution tests in vitro, and mechanical hardness (of dry tablets) were found to be sensitive to the cross-linking degree (cld) variation. Best release properties and highest mechanical hardness were obtained from CLHAS matrices with low-to-moderate crystallinity, where the V- and the B-type structures coexist with amorphous regions. X-ray and FTIR profiles of dry CLHAS powders were found to be predictive for release properties of CLHAS tablets.

A low temperature oxidation process has been developed to separate Pb from Zn in a complexly contaminated scrubber dust. The material consists of approx. 50% galena (PbS) and sphalerite/wurtzite (ZnS), and also an amorphous component, a variety of different silicate and carbonate phases as well as naturally-occurring radionuclides and oil and grease. The two-stage process consists of a grinding stage followed by placing this material into a hydrogen peroxide solution. The resultant oxidation reaction is violently exothermic — the temperature rises spontaneously to approx. 96°C. The amount of solid phases remaining after completion of the reaction was reduced by approx. 40% and consisted largely of insoluble lead sulphate which retained the bulk of the radionuclides. Almost all of the zinc was placed into solution by this process as was the Cd, Re and Cu. The total PAH content of the original Theisenschlamm (468 ppm) was reduced to 11.25 ppm in the residual sediment and the PCDD/PCDF concentrations were reduced by approx. 40%. The radionuclides are almost totally concentrated in the solid phase. The method shows considerable promise as a separation technique for very fine-grained sulphide-bearing residues.

A physical and chemical description of a scrubber dust slurry, known as Theisenschlamm, is presented. This material is generated as a by-product during extraction of copper from a mineralized Permian black shale (Kupferschiefer) in Sachsen-Anhalt, Germany. The Theisenschlamm consists of sulphide grains which are a complex solid solution of Pb, Zn, Cu and Fe. The crystal structures are modified forms of galena and sphalerite/wurtzite. Variations in the X-ray diffraction peak positions of these minerals reflect the poorly developed lattice structures of these phases. Anglesite is a secondary phase. The Theisenschlamm contains 18% Zn and 14% Pb as well as significant concentrations of PAH, PCDD and other organic compounds, rare metals and radionuclides (e.g. 210Po and 210Pb). The original particles have a median diameter of 1.25 μm, however, these particles are themselves aggregates of still smaller particles, typically of submicron size.