945 resultados para Nutrients and toxic elements


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Background: Adverse drug reactions (ADRs) cause significant morbidity and mortality and account for around 6.5% of hospital admissions. Patient experiences of serious ADRs and their long-term impact on patients' lives, including their influence on current attitudes towards medicines, have not been previously explored. Objective: The aim of the study was to explore the experiences, beliefs, and attitudes of survivors of serious ADRs, using drug-induced Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) as a paradigm. Methods: A retrospective, qualitative study was undertaken using detailed semi-structured interviews. Fourteen adult survivors of SJS and TEN, admitted to two teaching hospitals in the UK, one the location of a tertiary burns centre, were interviewed. Interview transcripts were independently analysed by three different researchers and themes emerging from the text identified. Results: All 14 patients were aware that their condition was drug induced, and all but one knew the specific drug(s) implicated. Several expressed surprise at the perceived lack of awareness of the ADR amongst healthcare professionals, and described how the ADR was mistaken for another condition. Survivors believed that causes of the ADR included (i) being given too high a dose of the drug; (ii) medical staff ignoring existing allergies; and (iii) failure to monitor blood tests. Only two believed that the reaction was unavoidable. Those who believed that the condition could have been avoided had less trust in healthcare professionals. The ADR had a persisting impact on their current lives physically and psychologically. Many now avoided medicines altogether and were fearful of becoming ill enough to need them. © 2011 Adis Data Information BV. All rights reserved. Conclusions: Life-threatening ADRs continued to affect patients’ lives long after the event. Patients’ beliefs regarding the cause of the ADR differed, and may have influenced their trust in healthcare professionals and medicines. We propose that clear communication during the acute phase of a serious ADR may therefore be important.

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Our goal was to quantify the coupled process of litter turnover and leaching as a source of nutrients and fixed carbon in oligotrophic, nutrient-limited wetlands. We conducted poisoned and non-poisoned incubations of leaf material from four different perennial wetland plants (Eleocharis spp., Cladium jamaicense, Rhizophora mangle and Spartina alterniflora) collected from different oligotrophic freshwater and estuarine wetland settings. Total phosphorus (TP) release from the P-limited Everglades plant species (Eleocharis spp., C. jamaicense and R. mangle) was much lower than TP release by the salt marsh plant S. alterniflora from N-limited North Inlet (SC). For most species and sampling times, total organic carbon (TOC) and TP leaching losses were much greater in poisoned than non-poisoned treatments, likely as a result of epiphytic microbial activity. Therefore, a substantial portion of the C and P leached from these wetland plant species was bio-available to microbial communities. Even the microbes associated with S. alterniflora from N-limited North Inlet showed indications of P-limitation early in the leaching process, as P was removed from the water column. Leaves of R. mangle released much more TOC per gram of litter than the other species, likely contributing to the greater waterborne [DOC] observed by others in the mangrove ecotone of Everglades National Park. Between the two freshwater Everglades plants, C. jamaicense leached nearly twice as much P than Eleocharis spp. In scaling this to the landscape level, our observed leaching losses combined with higher litter production of C. jamaicense compared to Eleocharis spp. resulted in a substantially greater P leaching from plant litter to the water column and epiphytic microbes. In conclusion, leaching of fresh plant litter can be an important autochthonous source of nutrients in freshwater and estuarine wetland ecosystems.

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The construction of artificial reefs in the oligotrophic seagrass meadows of central Florida Bay attracted large aggregations of fish and invertebrates, and assays of nutrient availability indicated increases in availability of nutrients to sediment microalgae, periphyton, and seagrasses around reefs. An average of 37.8 large (> 10 cm) mobile animals were observed on each small artificial reef. The dominant fish species present was the gray snapper (Lutjanus griseus Linnaeus, 1758). Four yrs after the establishment of the artificial reefs, microphytobenthos abundance was twice as high in reef plots (1.7 ± 0.1 μg chl-a cm-2) compared to control plots (0.9 ± 0.1 μg chl-a cm-2). The accumulation of periphyton on glass periphytometers was four times higher in artificial reef plots (200.1 ± 45.8 mg chl-a m-2) compared to control plots (54.8 ± 6.8 mg chl-a m-2). The seagrass beds surrounding the artificial reefs changed rapidly, from a sparse Thalassia testudinum (Banks & Soland. ex König) dominated community, which persisted at control plots, to a community dominated by Halodule wrightii (Ascherson). Such changes mirror the changes induced in experimentally fertilized seagrass beds in Florida, strongly suggesting that the aggregations of animals attracted by artificial reefs concentrated nutrients in this oligotrophic seascape, favoring the growth of fast-growing primary producers like microphytobenthos and periphyton, and changing the competitively dominant seagrass from slow-growing T. testudinum to faster-growing H. wrightii in the vicinity of the reefs.

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The timing and nature of the penultimate deglaciation, also known as Termination II (T-II), is subject of controversial discussions due to the scarcity of precisely-dated palaeoclimate records. Here we present a new precisely-dated and highly-resolved multi-proxy stalagmite record covering T-II from the high alpine Schafsloch Cave in Switzerland, an area where climate is governed by the North Atlantic. The inception of stalagmite growth at 137.4 ± 1.4 kyr before present (BP) indicates the presence of drip water and cave air temperatures of above 0 °C, and is related to a climate-induced change in the thermal state (from cold-to warm-based) of the glacier above the cave. The cessation of stalagmite growth between 133.1 ± 0.7 and 131.9 ± 0.6 kyr BP is most likely related to distinct drop in temperature associated with Heinrich stadial 11. The resumption of stalagmite growth at 131.9 ± 0.6 kyr BP is accompanied by an abrupt increase in temperature and precipitation as indicated by distinct shifts in the oxygen and carbon isotopic composition as well as in trace element concentrations. The mid-point of T-II is around 131.8 ± 0.6 kyr BP in the Schafsloch Cave record is significantly earlier compared to the age of 129.1 ± 0.1 kyr BP in the Sanbao Cave record from China. The different ages between both records can be best explained by the competing effects of insolation and glacial boundary forcing on seasonality and snow cover extent in Eurasia.

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Basement intersected in Holes 525A, 528, and 527 on the Walvis Ridge consists of submarine basalt flows and pillows with minor intercalated sediments. These holes are situated on the crest and mid- and lower NW flank of a NNW-SSE-trending ridge block which would have closely paralleled the paleo mid-ocean ridge. The basalts were erupted approximately 70 Ma, a date consistent with formation at the paleo mid-ocean ridge. The basalt types vary from aphyric quartz tholeiites on the Ridge crest to highly Plagioclase phyric olivine tholeiites on the flank. These show systematic differences in incompatible trace element and isotopic composition, and many element and isotope ratio pairs form systematic trends with the Ridge crest basalts at one end and the highly phyric Ridge flank basalts at the other. The low 143Nd/144Nd (0.51238) and high 87Sr/86Sr (0.70512) ratios of the Ridge crest basalts suggest derivation from an old Nd/Sm and Rb/Sr enriched mantle source. This isotopic signature is similar to that of alkaline basalts on Tristan da Cunha but offset by somewhat lower 143Nd/144Nd values. The isotopic ratio trends may be extrapolated beyond the Ridge flank basalts (which have 143Nd/144Nd of 0.51270 and 87Sr/86Sr of 0.70417) in the direction of typical MORB compositions. These isotopic correlations are equally consistent with mixing of depleted and enriched end-member melts or partial melting of an inhomogeneous, variably enriched mantle source. However, observed Zr-Ba-Nb-Y interelement relationships are inconsistent with any simple two-component model of magma mixing or partial melting. They also preclude extensive involvement of depleted (N-type) MORB material or its mantle sources in the petrogenesis of Walvis Ridge basalts.

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We present geochemical data of black smoker particulates filtered from hydrothermal fluids with seawater-dilutions ranging from 0-99%. Results indicate the dominance of sulphide minerals (Fe, Cu, and Zn sulphides) in all samples taken at different hydrothermal sites on the Mid-Atlantic Ridge. Pronounced differences in the geochemistry of the particles between Logatchev I and 5°S hydrothermal fields could be attributed to differences in fluid chemistry. Lower metal/sulphur ratios (Me/H2S < 1) compared to Logatchev I result in a larger amount of particles precipitated per liter fluid and the occurrence of elemental sulphur at 5°S, while at Logatchev I Fe oxides occur in larger amounts. Systematic trends with dilution degree of the fluid include the precipitation of large amounts of Cu sulphides at a low dilution and a pronounced drop with increasing dilution. Moreover, Fe (sulphides or oxides) precipitation increases with dilution of the vent fluid by seawater. Geochemical reaction path modeling of hydrothermal fluid-seawater mixing and conductive cooling indicates that Cu sulphide formation at Logatchev I and 5°S mainly occurs at high temperatures and low dilution of the hydrothermal fluid by seawater. Iron precipitation is enhanced at higher fluid dilution, and the different amounts of minerals forming at 5°S and Logatchev I are thermodynamically controlled. Larger total amounts of minerals and larger amounts of sulphide precipitate during the mixing path when compared to the cooling path. Differences between model and field observations do occur and are attributable to closed system modeling, to kinetic influences and possibly to organic constituents of the hydrothermal fluids not accounted for by the model.

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We examine the effects of seawater pCO2 concentration of 25, 41, and 76 kPa (250, 400, and 750 matm) on the growth rate of a natural assemblage of mixed phytoplankton obtained from a carefully controlled, 14-d mesocosm experiment. Throughout the experiment period, in all enclosures, two phytoplankton taxa (microflagellates and cryptomonads) and two diatom species (Skeletonema costatum and Nitzschia spp.) account for approximately 90% of the phytoplankton community. During the nutrient-replete period from day 9 to day 14 populations of Skeletonema costatum and Nitzschia spp. increased substantially; however, only Skeletonema costatum showed an increase in growth rate with increasing seawater pCO2. Not all diatom species in Korean coastal waters are sensitive to seawater pCO2 under nutrient-replete conditions.

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The coccolithophore Calcidiscus leptoporus was grown in batch culture under nitrogen (N) as well as phosphorus (P) limitation. Growth rate, particulate inorganic carbon (PIC), particulate organic carbon (POC), particulate organic nitrogen (PON), and particulate organic phosphorus (POP) production were determined and coccolith morphology was analysed. While PON production decreased by 70% under N-limitation and POP production decreased by 65% under P-limitation, growth rate decreased by 33% under N- as well as P-limitation. POC as well as PIC production (calcification rate) increased by 27% relative to the control under P-limitation, and did not change under N-limitation. Coccolith morphology did not change in response to either P or N limitation. While these findings, supported by a literature survey, suggest that coccolith morphogenesis is not hampered by either P or N limitation, calcification rate might be. The latter conclusion is in apparent contradiction to our data. We discuss the reasons for this inference.

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The evolution through time of trace element contents (Sr, Mg, Mn, and Fe) of sediments at Sites 549 and 550 is similar to that of previously studied oceanic sites. A comparison with some North Atlantic sites and with outcrops of the Gubbio section (Italy) allowed us to show that 1. A negative correlation between Sr and Mg contents, generally characteristic of pelagic carbonate having undergone diagenesis, is confirmed. 2. Magnesium diagenesis occurs over a relatively short time and is sensitive to the sedimentation rate of each individual time period, whereas Sr diagenesis is a long-term phenomenon and is sensitive to the overall average sedimentation rate at the site. Strontium loss by sediments is related to sediment age (i.e., residence time of sediments in a given diagenetic environment) and could be a rough method of dating individual sediment layers. 3. The nature of the seafloor (oceanic or continental) does not appear to play an important part in the content of Fe and Mn in sediments. Their distribution depends more on mid-oceanic ridge activity, paleodepth (through mediation of CaCO3 dissolution and environment), and distance of the site from the ridge.

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This data was collected during the 'ICE CHASER' cruise from the southern North Sea to the Arctic (Svalbard) in July-Aug 2008. This data consists of coccolithophore abundance, calcification and primary production rates, carbonate chemistry parameters and ancillary data of macronutrients, chlorophyll-a, average mixed layer irradiance, daily irradiance above the sea surface, euphotic and mixed layer depth, temperature and salinity.

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Mineralogical (microprobe) and geochemical (X-ray fluorescence, neutron activation analyses) data are given for 18 samples of volcanic rocks from the Guatemala Trench area (Deep Sea Drilling Project Leg 67). Typical fresh oceanic tholeiites occur in the trench itself (Hole 500) and in its immediate vicinity on the Cocos Plate (Site 495). Several samples (often reworked) of "spilitic" oceanic tholeiites are also described from the Trench: their mineralogy (greenschist facies association - actinolite + plagioclase + chlorite) and geochemistry (alteration, sometimes linked to manganese and zinc mineralization) are shown to result from high-temperature (300°-475°C) hydrothermal sea water-basalt interactions. The samples studied are depleted in light rare-earth elements (LREE), with the exception of the slightly LREE-enriched basalts from Hole 500. The occurrence of such different oceanic tholeiites in the same area is problematic. Volcanic rocks from the Guatemala continental slope (Hole 494A) are described as greenschist facies metabasites (actinolite + epidote + chlorite + plagioclase + calcite + quartz), mineralogically different from the spilites exposed on the Costa Rica coastal range (Nicoya Peninsula). Their primary magmatic affinity is uncertain: clinopyroxene and plagioclase compositions, together with titanium and other hygromagmaphile element contents, support an "active margin" affinity. The LREE-depleted patterns encountered in the present case, however, are not frequently found in orogenic samples but are typical of many oceanic tholeiites.