NUTRIENTS AND EUTROPHICATION IN THE TAW ESTUARY

Increased inputs of nutrients to estuaries and coastal waters can cause undesirable effects associated with eutrophication, including nuisance and toxic algal blooms, reduced amenity value, changes in species composition, bottom anoxia and fish kills. The main sources of nutrients to estuaries are river runoff, sewage discharges, atmospheric inputs and possibly submarine groundwater discharges. For the UK, estuarine eutrophication has been shown to occur in at least 16 estuaries (including the Taw in North Devon). Consequently, these systems have been designated as '(Potential) Problem Area' under the OSPAR Common Procedure for the Identification of Eutrophication and also as a 'Eutrophic Water' under the EU's Nitrates Directive and I or a 'Sensitive Area (Eutrophic)' under the Urban Wastewater Treatment Directive or both. Significant reductions in N and P inputs have been realized following application of the EU's Urban Waste Water Treatment Directive. Atmospheric NOx and NHx emissions have also decreased and are expected to decrease further as implementation of existing legislation continues and new controls are introduced for activities such as shipping. The Nitrates Directive was introduced to tackle N discharges from agriculture but little change in N loads to estuaries has been recorded. Using the Taw Estuary as an example, data routinely collected by the Environment Agency for England and Wales (EA) over the period 1990-2004 were interrogated to identify the drivers of excessive algal growth. The estuary was highly productive with chlorophyll a concentrations regularly exceeding 100 µg Lˉ¹ , mostly during periods of low freshwater input from the River Taw when estuarine water residence times were longest. The reported approach demonstrates the value of applying conventional statistical analyses in a structured way to existing monitoring data and is recommended as a useful tool for the rapid assessment of estuarine eutrophication. However, understanding of primary production dynamics in the Taw was constrained because of the low temporal resolution, heterogeneity and gaps in the EA data. Therefore, a temporal high resolution monitoring campaign was conducted in summer 2008 to document the development and decline of three algal blooms. The significance of long water residence times following low freshwater inflow and neap tides was confirmed. During peaks in chlorophyll a concentration (max. 226 µg Lˉ¹ ) , nutrient limitation switched from P to Si and persisted for more than 2 weeks in the outer estuary. Signs of ammonium and phosphate ( <0.2 µM) and silicate ( <2 µM) depletion were also observed. Using multivariate statistics, five distinct sets of environmental conditions present in the Taw at different stages of algal growth were identified and directly linked to freshwater inflow. UK Climate Impacts Programme scenarios predict a 30-50% decrease in Q95 flows (the flow which is exceeded 95% of the time) of rivers in south Britain by 2050. Under the current nutrient regime, this is likely to severely increase the severity and duration of symptoms of eutrophication in the Taw and favour potentially hazardous phytoplankton groups instead of diatoms. To mitigate future eutrophication events in the Taw, it is recommended to further reduce N and P inputs. It is also crucial to perform a detailed assessment of potential climate change consequences for the Taw Estuary and similar systems

Indentation unloading phase transformations in silicon: A new perspective

nanoindentation, silicon, Berkovich, contact pressure, continuous stiffness measuremen

Heterostructures of skutterudites and germanium antimony tellurides – structure analysis and thermoelectric properties of bulk samples

Heterostructures of germanium antimony tellurides with skutterudite-type precipitates are promising thermoelectric materials due to low thermal conductivity and multiple ways of tuning their electronic transport properties. Materials with the nominal composition [CoSb2(GeTe)_(0.5)]_x(GeTe)_(10.5)Sb_2Te_3 (x = 0–2) contain nano- to microscale precipitates of skutterudite-type phases which are homogeneously distributed. Powder X-ray diffraction reveals that phase transitions of the germanium antimony telluride matrix depend on its GeTe content. These are typical for this class of materials; however, the phase transition temperatures are influenced by heterostructuring in a beneficial way, yielding a larger existence range of the intrinsically nanostructured pseudocubic structure of the matrix. Using microfocused synchrotron radiation in combination with crystallite pre-selection by means of electron microscopy, single crystals of the matrix as well as of the precipitates were examined. They show nano-domain twinning of the telluride matrix and a pronounced structure distortion in the precipitates caused by GeTe substitution. Thermoelectric figures of merit of 1.4 ± 0.3 at 450 °C are observed. In certain temperature ranges, heterostructuring involves an improvement of up to 30% compared to the homogeneous material

SPHERES, J\"ulich's High-Flux Neutron Backscattering Spectrometer at FRM II

SPHERES (SPectrometer with High Energy RESolution) is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Juelich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 micro-eV, a dynamic range of +-31 micro-eV, and a signal-to-noise ratio of up to 1750:1.Comment: 12 pages, 7 figures, 2 tables. Supplemental material consists of 3 pages, 2 figures, 2 table

Significant impact of different oxygen breathing conditions on noninvasive in vivo tumor-hypoxia imaging using [18F]-fluoro-azomycinarabino-furanoside ([18F]FAZA)

<p>Abstract</p> <p>Background</p> <p>[¹⁸F]FAZA is a PET biomarker with great potential for imaging tumor hypoxia. Aim of our study was to compare [¹⁸F]FAZA uptake in mice with subcutaneous exogenous CT26 colon carcinomas and endogenous polyoma middle-T (PyV-mT) mammary carcinomas and to analyze the influence of different breathing protocols in CT26 colon carcinomas as well as the reversibility or irreversibility of [¹⁸F]FAZA uptake.</p> <p>Methods</p> <p>We injected subcutaneous CT26 colon carcinoma or polyomavirus middle-T (PyV-mT) mammary carcinoma-bearing mice intravenously with¹⁸F-FAZA and performed PET scans 1-3 h post injection (<it>p.i.</it>). To analyze the impact of oxygen supply in CT26 carcinomas we used three different breathing protocols: (P0) air; (P1) 100% oxygen 1 h prior injection until 3 h <it>p.i.</it>; (P2) 100% oxygen breathing starting 2 min prior tracer injection until 1 h <it>p.i. </it>and during the PET scans; mice were breathing air between the 2 h and 3 h 10 min static scans. Normalized PET images were analyzed by using defined regions of interest. Finally, some mice were dissected for pimonidazole immunohistochemistry.</p> <p>Results</p> <p>There was no difference in¹⁸F-FAZA uptake 1-3 h <it>p.i. </it>between the two carcinoma types (CT26: 1.58 ± 0.45%ID/cc; PyV-mT: 1.47 ± 0.89%ID/cc, 1 h <it>p.i.</it>, tumor size < 0.5 cm³). We measured a significant tracer clearance, which was more pronounced in muscle tissue (P0). The [¹⁸F]FAZA tumor-to-muscle-ratios in CT26 colon carcinoma-bearing mice 2 h and 3 h, but not 1 h <it>p.i. </it>were significantly higher when the mice breathed air (P0: 3.56 ± 0.55, 3 h) compared to the oxygen breathing protocols (P1: 2.45 ± 0.58; P2: 2.77 ± 0.42, 3 h). Surprisingly, the breathing protocols P1 and P2 showed no significant differences in T/M ratios, thus indicating that the crucial [¹⁸F]FAZA uptake phase is during the first hour after [¹⁸F]FAZA injection. Importantly, the muscle clearance was not affected by the different oxygen breathing conditions while the tumor clearance was lower when mice were breathing air.</p> <p>Conclusion</p> <p>Exogenous CT26 colon carcinomas and endogenous polyoma middle-T (PyV-mT) mammary carcinomas showed no differences in [¹⁸F]FAZA uptake 1-3 h <it>p.i. </it>Our analysis using various breathing protocols with air (P0) and with pure oxygen (P1, P2) clearly indicate that [¹⁸F]FAZA is an appropriate PET biomarker for <it>in vivo </it>analysis of hypoxia revealing an enhanced tracer uptake in tumors with reduced oxygen supply. [¹⁸F]FAZA uptake was independent of tumor-type.</p

Introduction of a guideline for measurements of greenhouse gas fluxes from soils using non-steady-state chambers

Method Soils represent a major global source and sink of greenhouse gases (GHGs). Many studies of GHG fluxes between soil, plant and atmosphere rely on chamber measurements. Different chamber techniques have been developed over the last decades, each characterised by different requirements and limitations. In this manuscript, we focus on the non-steady-state technique which is widely used for manual measurements but also in automatic systems. Although the measurement method appears very simple, experience gained over the years shows that there are many details which have to be taken into account to obtain reliable measurement results. Aim This manuscript aims to share lessons learnt and pass on experiences in order to assist the reader with possible questions or unexpected challenges, ranging from the planning of the design of studies and chambers to the practical handling of the chambers and the quality assurance of the gas and data analysis. This concise introduction refers to a more extensive Best Practice Guideline initiated by the Working Group Soil Gases (AG Bodengase) of the German Soil Science Society (Deutsche Bodenkundliche Gesellschaft). The intention was to collect and aggregate the expertise of different working groups in the research field. As a compendium, this Best Practice Guideline is intended to help both beginners and experts to meet the practical and theoretical challenges of measuring soil gas fluxes with non-steady-state chamber systems and to improve the quality of the individual flux measurements and thus entire GHG studies by reducing sources of uncertainty and error