Dynamic characteristics of sulfur, iron and phosphorus in coastal polluted sediments, north China

The cycling of sulfur (S), iron (Fe) and phosphorus (P) in sediments and pore water can impact the water quality of overlying water. In a heavily polluted river estuary (Yantai, China), vertical profiles of fluxes of dissolved sulfide, Fe2+ and dissolved reactive phosphorus (DRP) in sediment pore water were investigated by the Diffusive Gradients in Thin films technique (DGT). Vertical fluxes of S, Fe, P in intertidal sediment showed the availability of DRP increased while the sulfide decreased with depth in surface sediment, indicating that sulfide accumulation could enhance P release in anoxic sediment. In sites with contrasting salinity, the relative dominance of iron and sulfate reduction was different, with iron reduction dominant over sulfate reduction in the upper sediment at an intertidal site but the reverse true in a freshwater site, with the other process dominating at depth in each case. Phosphate release was largely controlled by iron reduction

Groundwater dependent ecosystems. Part I: Hydroecological status and trends

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Paired dissolved and particulate phase Cu isotope distributions in the South Atlantic

© 2018 The Authors Copper (Cu) is both an essential micronutrient and toxic to photosynthesizing microorganisms at low concentrations. Its dissolved vertical distribution in the oceans is unusual, being neither a nutrient-type nor scavenged-type element. This distribution is attributed to biological uptake in the surface ocean with remineralisation at depth, combined with strong organic complexation by dissolved ligands, scavenging onto particles, and benthic sedimentary input. We present coupled dissolved and particulate phase Cu isotope data along the UK-GEOTRACES South Atlantic section, alongside higher resolution dissolved and particulate phase Cu concentration measurements. Our dissolved phase isotope data contribute to an emerging picture of homogeneous deep ocean δ65Cu, at about +0.65‰ (relative to NIST SRM 976). We identify two pools of Cu in the particulate phase: a refractory, lithogenic pool, at about 0‰, and a labile pool accessed via a weak acidic leach, at about +0.4‰. These two pools are comparable to those previously observed in sediments. We observe deviations towards lighter δ65Cu values in the dissolved phase associated with local enrichments in particulate Cu concentrations along the continental slopes, and in the surface ocean. Copper isotopes are thus a sensitive indicator of localised particle-associated benthic or estuarine Cu inputs. The measurement of Cu isotopes in seawater is analytically challenging, and we call for an intercalibration exercise to better evaluate the potential impacts of UV-irradiation, storage time, and different analytical procedures

A three-dimensional reactive transport model for sediments, incorporating microniches.

Most reactive transport models have represented sediments as one-dimensional (1-D) systems and have solely considered the development of vertical concentration gradients. However, application of recently developed micro-scale and 2-D measurement techniques have demonstrated more complicated solute structures in some sediments, including discrete localized sites of depleted oxygen, and elevated trace metals and sulphide, referred to as microniches. A model of transport and reaction in sediments, that can simulate the dynamic development of concentration gradients occurring in 3-D, was developed. Its graphical user interface (GUI) allows easy input of user-specified reactions and provides flexible schemes that prioritise their execution. The 3-D capability was demonstrated by quantitative modelling of hypothetical solute behaviour at organic matter microniches covering a range of sizes. Significant effects of microniches on the profiles of oxygen and nitrate are demonstrated. Sulphide is shown to be readily generated in microniches within one centimetre of the sediment surface, provided the diameter of the reactive organic material is greater than one millimetre. These modelling results illustrate the geochemical complexities that arise when processes occur in 3-D and demonstrate the need for such a model. Future use of high-resolution measurement techniques should include the collection of data for relevant major components, such as reactive iron and manganese oxides, to allow full, multi-component modelling of microniche processes

Serologi för böldsjuka hos får och get - validering av en indirekt ELISA och uppskattning av seroprevalensen i Sverige

Caseous lymphadenitis (CLA) is a disease primarily in sheep and goats, caused by Corynebacterium pseudotuberculosis, characterized by abscess formation in external and/or internal lymph nodes and organs. Economic losses occur due to emaciation, reduced milk production and impaired growth in affected animals. At the Swedish Veterinary Agency, bacterial culture is used as a diagnostic method for detecting CLA, requiring puncture of clinical abscesses. This sampling method increases the risk for disease transmission and overlooks animals affected by internal abscesses. In this study, a commercially available enzyme-linked immunosorbent assay (ELISA)-kit, based on an indirect ELISA, was validated for detecting antibodies for CLA, aiming for a more cost-effective and safer method that also can detect animals with internal abscesses. Serum and milk samples were analyzed to investigate the concordance between the two sample types. A subset of serum and milk samples was sent to Norway for analysis to compare the ELISA results, and comparison with another laboratory's results was conducted. The ELISA-kit demonstrated high sensitivity (92% for serum, 100% for milk), crucial for controlling CLA at herd level, while the specificity was estimated at 68% for serum and 61% for milk. To avoid increased and unnecessary culling of animals, a confirmatory method should analyze positive individuals to increase the specificity. Pooled milk samples could reduce costs for herd-level analysis, followed by serum sampling for positive herds

High-resolution two-dimensional quantitative analysis of phosphorus, vanadium and arsenic, and qualitative analysis of sulphide, in a freshwater sediment.

Recently introduced techniques that can provide two-dimensional images of solution concentrations in sediments for multiple analytes have revealed discrete sites of geochemical behaviour different from the average for that depth (microniches). We have developed a new preparation method for a binding phase, incorporated in a hydrogel, for the diffusive gradients in thin-films (DGT) technique. It allows co-analysis of sulphide and the reactive forms of phosphorus, vanadium and arsenic in the porewaters at the surface of the device. This gel, when dried and analysed using laser ablation mass spectrometry, allows the acquisition of high-resolution, sub-millimetre-scale, data. The binding phase was deployed within a DGT device in a sediment core collected from a productive lake, Esthwaite Water (UK). Localized removal from the porewaters of the sediment for phosphate and vanadium has been demonstrated at a microniche of local sulphide production. The possible removal processes, including bacterial uptake and reduction of vanadate to insoluble VIII by sulphide, are discussed. Understanding processes occurring at this scale may allow improved prediction of pollutant fate and better prediction of past climates where trace metals are used as paleoredox proxies