Identifying critical source areas using multiple methods for effective diffuse pollution mitigation.

Diffuse pollution from agriculture constitutes a key pressure on the water quality of freshwaters and is frequently the cause of ecological degradation. The problem of diffuse pollution can be conceptualised with a source-mobilisation-pathway (or delivery)-impact model, whereby the combination of high source risk and strong connected pathways leads to 'critical source areas' (CSAs). These areas are where most diffuse pollution will originate, and hence are the optimal places to implement mitigation measures. However, identifying the locations of these areas is a key problem across different spatial scales within catchments. A number of approaches are frequently used for this assessment, although comparisons of these assessments are rarely carried out. We evaluate the CSAs identified via traditional walkover surveys supported by three different approaches, highlighting their benefits and disadvantages. These include a custom designed smartphone app; a desktop geographic information system (GIS) and terrain analysis-based SCIMAP (Sensitive Catchment Integrated Modelling and Analysis Platform) approach; and the use of a high spatial resolution drone dataset as an improved input data for SCIMAP modelling. Each of these methods captures the locations of the CSAs, revealing similarities and differences in the prioritisation of CSA features. The differences are due to the temporal and spatial resolution of the three methods such as the use of static land cover information, the ability to capture small scale features, such as gateways and the incomplete catchment coverage of the walkover survey. The relative costs and output resolutions of the three methods indicate that they are suitable for application at different catchment scales in conjunction with other methods. Based on the results in this paper, it is recommended that a multi-evidence-based approach to diffuse pollution management is taken across catchment spatial scales, incorporating local knowledge from the walkover with the different data resolutions of the SCIMAP approach.

Strong and recurring seasonality revealed within stream diatom assemblages.

Improving stream water quality in agricultural landscapes is an ecological priority and a legislative duty for many governments. Ecosystem health can be effectively characterised by organisms sensitive to water quality changes such as diatoms, single-celled algae that are a ubiquitous component of stream benthos. Diatoms respond within daily timescales to variables including light, temperature, nutrient availability and flow conditions that result from weather and land use characteristics. However, little consideration has been given to the ecological dynamics of diatoms through repeated seasonal cycles when assessing trajectories of stream function, even in catchments actively managed to reduce human pressures. Here, six years of monthly diatom samples from three independent streams, each receiving differing levels of diffuse agricultural pollution, reveal robust and repeated seasonal variation. Predicted seasonal changes in climate-related variables and anticipated ecological impacts must be fully captured in future ecological and water quality assessments, if the apparent resistance of stream ecosystems to pollution mitigation measures is to be better understood.

Use of spatially distributed time-integrated sediment sampling networks and distributed fine sediment modelling to inform catchment management.

Under the EU Water Framework Directive, suspended sediment is omitted from environmental quality standards and compliance targets. This omission is partly explained by difficulties in assessing the complex dose-response of ecological communities. But equally, it is hindered by a lack of spatially distributed estimates of suspended sediment variability across catchments. In this paper, we demonstrate the inability of traditional, discrete sampling campaigns for assessing exposure to fine sediment. Sampling frequencies based on Environmental Quality Standard protocols, whilst reflecting typical manual sampling constraints, are unable to determine the magnitude of sediment exposure with an acceptable level of precision. Deviations from actual concentrations range between -35 and +20% based on the interquartile range of simulations. As an alternative, we assess the value of low-cost, suspended sediment sampling networks for quantifying suspended sediment transfer (SST). In this study of the 362 km2 upland Esk catchment we observe that spatial patterns of sediment flux are consistent over the two year monitoring period across a network of 17 monitoring sites. This enables the key contributing sub-catchments of Butter Beck (SST: 1141 t km2 yr-1) and Glaisdale Beck (SST: 841 t km2 yr-1) to be identified. The time-integrated samplers offer a feasible alternative to traditional infrequent and discrete sampling approaches for assessing spatio-temporal changes in contamination. In conjunction with a spatially distributed diffuse pollution model (SCIMAP), time-integrated sediment sampling is an effective means of identifying critical sediment source areas in the catchment, which can better inform sediment management strategies for pollution prevention and control.

Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments.

We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~10km(2)) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+8% to +17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target controllable risk factors, such as soil nutrient status, soil condition and crop cover.

Dominant mechanisms for the delivery of fine sediment and phosphorus to fluvial networks draining grassland dominated headwater catchments.

Recent advances in monitoring technology have enabled high frequency, in-situ measurements of total phosphorus and total reactive phosphorus to be undertaken with high precision, whilst turbidity can provide an excellent surrogate for suspended sediment. Despite these measurements being fundamental to understanding the mechanisms and flow paths that deliver these constituents to river networks, there is a paucity of such data for headwater agricultural catchments. The aim of this paper is to deduce the dominant mechanisms for the delivery of fine sediment and phosphorus to an upland river network in the UK through characterisation of the temporal variability of hydrological fluxes, and associated soluble and particulate concentrations for the period spanning March 2012-February 2013. An assessment of the factors producing constituent hysteresis is undertaken following factor analysis (FA) on a suite of measured environmental variables representing the fluvial and wider catchment conditions prior to, and during catchment-wide hydrological events. Analysis indicates that suspended sediment is delivered to the fluvial system predominantly via rapidly responding pathways driven by event hydrology. However, evidence of complex, figure-of-eight hysteresis is observed following periods of hydrological quiescence, highlighting the importance of preparatory processes. Sediment delivery via a slow moving, probably sub-surface pathway does occur, albeit infrequently and during low magnitude events at the catchment outlet. Phosphorus is revealed to have a distinct hysteretic response to that of suspended sediment, with sub-surface pathways dominating. However, high magnitude events were observed to exhibit threshold-like behaviour, whereby activation and connection of usually disconnected depositional zones to the fluvial networks results in the movement of vast phosphorus fluxes. Multiple pathways are observed for particulate and soluble constituents, highlighting the challenges faced in mitigating the delivery of contaminant fluxes to headwater river systems.

High frequency variability of environmental drivers determining benthic community dynamics in headwater streams.

Headwater streams are an important feature of the landscape, with their diversity in structure and associated ecological function providing a potential natural buffer against downstream nutrient export. Phytobenthic communities, dominated in many headwaters by diatoms, must respond to physical and chemical parameters that can vary in magnitude within hours, whereas the ecological regeneration times are much longer. How diatom communities develop in the fluctuating, dynamic environments characteristic of headwaters is poorly understood. Deployment of near-continuous monitoring technology in sub-catchments of the River Eden, NW England, provides the opportunity for measurement of temporal variability in stream discharge and nutrient resource supply to benthic communities, as represented by monthly diatom samples collected over two years. Our data suggest that the diatom communities and the derived Trophic Diatom Index, best reflect stream discharge conditions over the preceding 18-21 days and Total Phosphorus concentrations over a wider antecedent window of 7-21 days. This is one of the first quantitative assessments of long-term diatom community development in response to continuously-measured stream nutrient concentration and discharge fluctuations. The data reveal the sensitivity of these headwater communities to mean conditions prior to sampling, with flow as the dominant variable. With sufficient understanding of the role of antecedent conditions, these methods can be used to inform interpretation of monitoring data, including those collected under the European Water Framework Directive and related mitigation efforts.

Protein and mineral characterisation of rendered meat and bone meal.

We report the characterisation of meat and bone meal (MBM) standards (Set B-EFPRA) derived from cattle, sheep, pig and chicken, each rendered at four different temperatures (133, 137, 141 and 145 °C). The standards, prepared for an EU programme STRATFEED (to develop new methodologies for the detection and quantification of illegal addition of mammalian tissues in feeding stuffs), have been widely circulated and used to assess a range of methods for identification of the species composition of MBM. The overall state of mineral alteration and protein preservation as a function of temperature was monitored using small angle X-ray diffraction (SAXS), amino acid composition and racemization analyses. Progressive increases in protein damage and mineral alteration in chicken and cattle standards was observed. In the case of sheep and pig, there was greater damage to the proteins and alteration of the minerals at the lowest treatment temperature (133 °C), suggesting that the thermal treatments must have been compromised in some way. This problem has probably impacted upon the numerous studies which tested methods against these heat treatments. We use protein mass spectrometric methods to explore if thermostable proteins could be used to identify rendered MBM. In more thermally altered samples, so-called 'thermostable' proteins such as osteocalcin which has been proposed as a ideal target to speciate MBM were no longer detectable, but the structural protein type I collagen could be used to differentiate all four species, even in the most thermally altered samples.

Manganese oxidation state mediates toxicity in PC12 cells.

The role of the manganese (Mn) oxidation state on cellular Mn uptake and toxicity is not well understood. Therefore, undifferentiated PC12 cells were exposed to 0-200 microM Mn(II)-chloride or Mn(III)-pyrophosphate for 24 h, after which cellular manganese levels were measured along with measures of cell viability, function, and cytotoxicity (trypan blue exclusion, medium lactate dehydrogenase (LDH), 8-isoprostanes, cellular ATP, dopamine, serotonin, H-ferritin, transferrin receptor (TfR), Mn-superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (CuZnSOD) protein levels). Exposures to Mn(III) >10 microM produced 2- to 5-fold higher cellular manganese levels than equimolar exposures to Mn(II). Cell viability and ATP levels both decreased at the highest Mn(II) and Mn(III) exposures (150-200 microM), while Mn(III) exposures produced increases in LDH activity at lower exposures (> or =50 microM) than did Mn(II) (200 microM only). Mn(II) reduced cellular dopamine levels more than Mn(III), especially at the highest exposures (50% reduced at 200 microM Mn(II)). In contrast, Mn(III) produced a >70% reduction in cellular serotonin at all exposures compared to Mn(II). Different cellular responses to Mn(II) exposures compared to Mn(III) were also observed for H-ferritin, TfR, and MnSOD protein levels. Notably, these differential effects of Mn(II) versus Mn(III) exposures on cellular toxicity could not simply be accounted for by the different cellular levels of manganese. These results suggest that the oxidation state of manganese exposures plays an important role in mediating manganese cytotoxicity.

Multiple geminate ligand recombinations in human hemoglobin.

The geminate ligand recombination reactions of photolyzed carbonmonoxyhemoglobin were studied in a nanosecond double-excitation-pulse time-resolved absorption experiment. The second laser pulse, delayed by intervals as long as 400 ns after the first, provided a measure of the geminate kinetics by rephotolyzing ligands that have recombined during the delay time. The peak-to-trough magnitude of the Soret band photolysis difference spectrum measured as a function of the delay between excitation pulses showed that the room temperature kinetics of geminate recombination in adult human hemoglobin are best described by two exponential processes, with lifetimes of 36 and 162 ns. The relative amounts of bimolecular recombination to T- and R-state hemoglobins and the temperature dependence of the submicrosecond kinetics between 283 and 323 K are also consistent with biexponential kinetics for geminate recombination. These results are discussed in terms of two models: geminate recombination kinetics modulated by concurrent protein relaxation and heterogeneous kinetics arising from alpha and beta chain differences.

Abdominal aortic injury associated with transverse lumbar spine fracture--imaging findings.

The association of abdominal aortic injury with transverse fractures of the lumbar spine is not well recognized. Three cases are presented with description of a mechanism common to both injuries that may explain this association--that of distraction and hyperflexion, such as occurs in seat-belt injuries. Whenever a transverse lumbar spine fracture following such a mechanism of injury is recognized, the co-existence of an injury to the abdominal aorta should be excluded by aortography if there is any doubt concerning the integrity of the peripheral pulses. This is best performed prior to laparotomy for any associated intraperitoneal injuries. Repeated clinical examination may detect deterioration in those cases with initially normal pulses. Ultimately, detection of the aortic injury rests on a high index of suspicion.

Pictorial review: CT appearances of contrast medium extravasations associated with injury sustained from blunt abdominal trauma.

Contrast-enhanced CT is a valuable imaging modality in detecting extravasation of intravascular, urinary tract of gastrointestinal contrast medium in major blunt trauma victims. This pictorial review illustrates the CT appearance associated with extravasation of contrast medium from these various sites and emphasizes features that differentiate among them.

Psychological effects of participation and nonparticipation in a placebo-controlled zidovudine clinical trial with asymptomatic human immunodeficiency virus-infected individuals.

Psychological effects of participation in Protocol 019, a zidovudine placebo-controlled clinical trial, were investigated. Forty-six Protocol 019 subjects and 27 control asymptomatic human immunodeficiency virus-seropositive subjects were assessed at entry, 2 months, 6 months, and after trial modification. At baseline there were no psychological differences. Most Protocol 019 and control subjects were depressed on at least one psychological measure; fewer were anxious. Both groups had improvement over time. By 6 months, Protocol 019 subjects had decreased Beck Depression Inventory (BDI) scores, state anxiety, stress reaction, and symptoms of depression and anxiety. Controls had decreased scores on only the BDI. Over time, the percentage meeting modified DSM III-R criteria for anxiety decreased in both groups and the proportion of Protocol 019 subjects meeting DSM III-R depression criteria decreased. After protocol modification, study subjects were less depressed and distressed than controls. Protocol 019 subjects reduced depression symptoms but controls did not. Clinical trial participation was not deleterious and may have yielded some relative psychological benefit.

Identification of the L-tartrate dehydratase genes (ttdA and ttdB) of Escherichia coli and evolutionary relationship with the class I fumarase genes.

The genes encoding an oxygen-labile stereospecific L-tartrate dehydratase (L-Ttd, EC 4.2.1.32) have been identified as the orfZ1 and orfZ2 genes located upstream of the rpsU-dnaG-rpoD operon at 67 min in the Escherichia coli linkage map. They were previously cloned and sequenced by M. Nesin and others (Gene 51, 149-161, 1987) and have now been independently cloned, partially resequenced, and designated as an operon (ttdAB) containing two translationally coupled genes. The enzyme behaves as a tetramer (M(r) 105,000) containing two pairs of non-identical subunits, TtdA (M(r) 32589) and TtdB (M(r) 22641), which otherwise resembles the homodimeric iron-sulphur-containing Class I fumarases of E. coli and Bacillus stearothermophilus. The amino acid sequences of the TtdA-TtdB subunits are colinearly related to a single fumarase subunit, indicating a common evolutionary ancestry. E. coli can use L-, D- and meso-tartrates as aerobic growth substrates and as reducible substrates for supporting anaerobic growth on glycerol. L-Ttd was induced during anaerobic growth on glycerol plus L- and meso-tartrates, and a stereospecific D-tartrate dehydratase was induced by all three stereoisomers under comparable conditions. No meso-tartrate dehydratase was detected, nor were any dehydratases detected after aerobic growth on tartrate minimal media suggesting that different catabolic routes operate under aerobic conditions.

Molecular and enzymological evidence for two classes of fumarase in Bacillus stearothermophilus (var. non-diastaticus).

The gene (fumABst) encoding an oxygen-labile fumarase of Bacillus stearothermophilus has been cloned and sequenced. The structural gene (1542 bp) encodes a product (FumABst) of M(r) 56,788 containing 514 amino acid residues. The amino acid sequence is 23% identical (37% similar) to FumA and FumB, the labile [4Fe-4S]-containing fumarases (Class I enzymes) of Escherichia coli. It exhibits no significant similarity to FumC and CitG, the stable fumarases (Class II enzymes) of E. coli and Bacillus subtilis (respectively). Enzymological studies indicated that FumABst resembles the iron-sulphur-containing fumarases in being dimeric (M(r) 2 x 58,500), oxygen labile and partially reactivated by Fe2+ plus DTT. The fumABst gene is the first gene encoding a Class I fumarase to be characterized in any organism other than E. coli. Enzymological and DNA-hybridization studies further indicated that B. stearothermophilus resembles E. coli in containing an oxygen-stable fumarase (Class II enzyme). Sequence comparisons revealed significant similarities between the Class I fumarases and the products of adjacent open-reading frames (orfZ1 and orfZ2) located upstream of the macromolecular synthesis operon (rpsU-dnaG-rpoD) at 67 min in the E.coli linkage map. Located downstream of fumABst, there is an unidentified gene (orf2), which is homologous to the rhizobial nodB genes involved in the initiation of root nodule formation.

Fading teacher prompts from peer-initiation interventions for young children with disabilities.

This study examined a system for fading teacher prompts to children who served as peers in peer-initiation interventions for young children with disabilities. A teacher taught peers to direct social initiations to children with disabilities, provided verbal prompts for those initiations, and introduced a system that provided peers with visual feedback about the social interactions of the children with disabilities. She then systematically withdrew the verbal prompts to peers, and subsequently faded the visual feedback system. Peer initiations increased when the intervention began and resulted in increases in social interaction for the children with disabilities. As the teacher systematically faded the prompts and visual feedback to the peers, social interaction continued at the levels found during intervention and was maintained during a short maintenance period.

Interactions of retinoic acid and androgens in human prostatic tissue.

The effect of retinoic acid (RA) on testosterone metabolic pathway was investigated in hyperplastic and neoplastic human prostatic tissues, and also the effects of steroids on RA binding to its receptor. Steroids only had a minimal effect on the binding of RA by its receptor. The conversion of testosterone to DHT by 5 alpha-reductase was reduced in the presence of retinoic acid. The inhibition was probably due to competition with NADPH for enzyme binding sites. The degree of inhibition found with retinoic acid at a concentration of 10(-4)M was greater for hyperplastic (41%) than that for neoplastic tissue (24%). The inhibition of 5 alpha-reductase by retinoic acid was dose-dependent. The activity of 5 alpha-reductase is significantly less in neoplastic compared with hyperplastic tissue.