Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments

We report the development of a modified method for evaluating different reservoirs of sedimentary phosphorus (P) in ancient marine sedimentary rocks and in modern Fe-rich sediments. Utilising the existing SEDEX scheme for P partitioning in modern sediments, we initially demonstrate limitations in the application of the original scheme to sediments and rocks containing crystalline hematite and magnetite. We tested additional extractions for these crystalline Fe phases, using both synthetic minerals, and modern and ancient sediments. The addition of 6 h oxalate and 6 h citrate-dithionate-acetate extractions considerably enhanced the total recovery of synthetic magnetite and hematite to 88.7 ± 1.1% and 76.9 ± 3.8%, respectively. In addition, application of the 6 h oxalate extraction to synthetic P-containing magnetite recovered 93.9 ± 1.7% of the Fe present and 88.2 ± 12.8% of the co-precipitated P. Based upon these results we developed a modified SEDEX extraction scheme. The modified scheme was applied to modern Fe-rich sediments from Golfo Dulce, Costa Rica, which resulted in 16% higher Fe-bound P recovery. Application of the scheme to a variety of ancient marine rocks increased the recovery of Fe-bound P by up to 22%. We also highlight the potential for authigenic carbonate fluorapatite to convert to more crystalline apatite in ancient rocks during deep burial and metamorphism. We suggest that in such systems minimum and maximum estimates of the total reactive P pool may be calculated with and without the inclusion of crystalline P. It is noted that the application of the revised method may have important implications for understanding the cycling of P in ancient marine environments

Potentially bioavailable iron delivery by iceberg-hosted sediments and atmospheric dust to the polar oceans

Iceberg-hosted sediments and atmospheric dust transport potentially bioavailable iron to the Arctic and Southern oceans as ferrihydrite. Ferrihydrite is nanoparticulate and more soluble, as well as potentially more bioavailable, than other iron (oxyhydr)oxide minerals (lepidocrocite, goethite, and hematite). A suite of more than 50 iceberghosted sediments contain a mean content of 0.076 wt% Fe as ferrihydrite, which produces iceberg-hosted Fe fluxes ranging from 0.7 to 5.5 and 3.2 to 25 Gmoles yr 1 to the Arctic and Southern oceans respectively. Atmospheric dust (with little or no combustion products) contains a mean ferrihydrite Fe content of 0.038 wt% (corresponding to a fractional solubility of 1 %) and delivers much smaller Fe fluxes (0.02–0.07 Gmoles yr 1 to the Arctic Ocean and 0.0– 0.02 Gmoles yr 1 to the Southern Ocean). New dust flux data show that most atmospheric dust is delivered to sea ice where exposure to melting/re-freezing cycles may enhance fractional solubility, and thus fluxes, by a factor of approximately 2.5. Improved estimates for these particulate sources require additional data for the iceberg losses during fjord transit, the sediment content of icebergs, and samples of atmospheric dust delivered to the polar regions

The effect of atmospheric acid processing on the global deposition of bioavailable phosphorus from dust

The role of dust as a source of bioavailable phosphorus (Bio-P) is quantified using a new parameterization for apatite dissolution in combination with global soil data maps and a global aerosol transport model. Mineral dust provides 31.2 Gg-P yr-1 of Bio-P to the oceans, with 14.3 Gg-P yr-1 from labile P present in the dust, and an aditional 16.9 Gg-P yr from acid dissolution of apatite in the atmosphere, representing an increase of 120%. The North Atlantic, north west Pacific, and Mediterranean Sea are identified as important sites of Bio-P deposition from mineral dust. The acid dissolution process increases the fraction of total-P that is bioavailable from ~10% globally from the labile pool to 23% in the Atlantic Ocean, 45% in the Pacific Ocean, and 21% in the Indian Ocean, with an ocean global mean value of 22%. Strong seasonal variations, especially in the North Pacific, northwest Atlantic, and Indian Ocean, are driven by large-scale meteorology and pollution sources from industrial and biomass-burning regions. Globally constant values of total-P content and bioavailable fraction used previously do not capture the simulated variability. We find particular sensitivity to the representation of particle-to-particle variability of apatite, which supplies Bio-P through acid-dissolution, and calcium carbonate, which helps to buffer the dissolution process. A modest 10% external mixing results in an increase of Bio-P deposition by 18%. The total Bio-P calculated here (31.2 Gg-P yr-1) represents a minimum compared to previous estimates due to the relatively low total-P in the global soil map used

Cryo-Vacuum Testing of the Integrated Science Instrument Module for the James Webb Space Telescope

With delivery of the science instruments for the James Webb Space Telescope (JWST) to Goddard Space Flight Center (GSFC) expected in 2012, current plans call for the first cryo-vacuum test of the Integrated Science Instrument Module (ISIM) to be carried out at GSFC in early 2013. Plans are well underway for conducting this ambitious test, which will perform critical verifications of a number of optical, thermal, and operational requirements of the IS 1M hardware, at its deep cryogenic operating temperature. We describe here the facilities, goals, methods, and timeline for this important Integration & Test milestone in the JWST program

Coastal upwelling in the Rias Bajas, NW Spain: Contrasting the benthic regimes of the Rias de Arosa and de Muros

Nutrient-rich North Atlantic water upwells off the NW coast of Spain and intermittently intrudes into the rias, coastal embayments, by displacement during periods of offshore winds. High primary production associated with the upwelling supports an intensive raft culture of the edible mussel, Mytilus edulis. This culture is most intensive (ca. 2000 rafts) in the Ria de Arosa, and results in one of the highest protein yields per unit area on earth...

Benthic ecology of semi-natural coastal lagoons, in the Ria Formosa (Southern Portugal), Exposed to different water renewal regimes

Several studies in semi-natural coastal lagoons in the Ria Formosa lagoonal system have been carried out. These man-made water reservoirs behave as small lagoons with one opening to the tidal channels, which may be intermittent. Because of their size, these reservoirs are ideal sites for ecological studies. Water quality and macrobenthic fauna were analysed in five water reservoirs. All reservoirs received the same incoming water through a tidal channel, but they differed in water renewal regime. Multidimensional Scaling (MDS) and Discriminant Analysis were used to evaluate the similarity among sites, stations and sampling occasions. Different levels of taxonomic resolution (family, large taxonomic groups and phylum level) were also evaluated. The separation of sites and stations became unclear using high taxonomic levels. Results from the multivariate analyses suggest a slight differentiation of the stations according to sampling occasion but a clear differentiation of the several water reservoirs. Some of the lagoons studied with low water renewal rates showed strong environmental variations. They were characterised by low diversity indexes and abundance of small-sized organisms. Other lagoons, with high water renewal rates, showed low environmental variation and well diversified and structured benthic communities. The main environmental factor that seems to affect the benthic communities was the variation in salinity between neap and spring tides, which is related with the water renewal regime. Coastal lagoons offer a protected shallow habitat, which can be highly productive. Well structured communities, controlled by k-strategists, can develop and settle in leaky lagoons, that is, lagoons with wide entrance channels and tidal currents which guarantee a good water renewal. In these lagoons, biomass can accumulate in large organisms. In contrast, lagoons with a single narrow entrance, that may be closed for long periods, are characterised by persistent physical stress and are dominated by communities of small-sized r-strategists

Iterative in situ click chemistry creates antibody-like protein-capture agents

Iterative in situ click chemistry (see scheme for the tertiary ligand screen) and the one-bead-one-compound method for the creation of a peptide library enable the fragment-based assembly of selective high-affinity protein-capture agents. The resulting ligands are water-soluble and stable chemically, biochemically, and thermally. They can be produced in gram quantities through copper (I)-catalyzed cycloaddition

Coastal upwelling in the Rías Bajas, NW Spain: Contrasting the benthic regimes of Rías de Arosa and de Muros

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Power grip, pinch grip, manual muscle testing or thenar atrophy - which should be assessed as a motor outcome after carpal tunnel decompression? A systematic review

<p>Abstract</p> <p>Background</p> <p>Objective assessment of motor function is frequently used to evaluate outcome after surgical treatment of carpal tunnel syndrome (CTS). However a range of outcome measures are used and there appears to be no consensus on which measure of motor function effectively captures change. The purpose of this systematic review was to identify the methods used to assess motor function in randomized controlled trials of surgical interventions for CTS. A secondary aim was to evaluate which instruments reflect clinical change and are psychometrically robust.</p> <p>Methods</p> <p>The bibliographic databases Medline, AMED and CINAHL were searched for randomized controlled trials of surgical interventions for CTS. Data on instruments used, methods of assessment and results of tests of motor function was extracted by two independent reviewers.</p> <p>Results</p> <p>Twenty-two studies were retrieved which included performance based assessments of motor function. Nineteen studies assessed power grip dynamometry, fourteen studies used both power and pinch grip dynamometry, eight used manual muscle testing and five assessed the presence or absence of thenar atrophy. Several studies used multiple tests of motor function. Two studies included both power and pinch strength and reported descriptive statistics enabling calculation of effect sizes to compare the relative responsiveness of grip and pinch strength within study samples. The study findings suggest that tip pinch is more responsive than lateral pinch or power grip up to 12 weeks following surgery for CTS.</p> <p>Conclusion</p> <p>Although used most frequently and known to be reliable, power and key pinch dynamometry are not the most valid or responsive tools for assessing motor outcome up to 12 weeks following surgery for CTS. Tip pinch dynamometry more specifically targets the thenar musculature and appears to be more responsive. Manual muscle testing, which in theory is most specific to the thenar musculature, may be more sensitive if assessed using a hand held dynamometer – the Rotterdam Intrinsic Handheld Myometer. However further research is needed to evaluate its reliability and responsiveness and establish the most efficient and psychometrically robust method of evaluating motor function following surgery for CTS.</p