Nitrate and water supplies in the United Kingdom

Nitrate concentrations in UK waters are rising, with the highest levels occurring in the south and east of England, particularly Lincolnshire, Cambridgeshire and East Anglia. The source of the nitrate is arable agriculture where intensification in the last few decades has increased nitrate leaching from soils into both surface and underground waters. Concentrations in underground waters are expected to reach 150 to 200 mg litre(-1) nitrate (i.e. NO(3)) in the future, if agricultural losses remain stable. No widespread environmental deterioration due to nitrate has been observed in rivers or lakes. Excessive concentrations of nitrate in drinking waters can cause methaemoglobinaemia (blue-baby syndrome) in bottle-fed infants and the government Chief Medical Officer has recommended that a maximum concentration of 100 mg litre(-1) is appropriate for public water supplies in the UK. This level has not been exceeded in public water supplies in the UK, but maintaining it has cost approximately 15m pounds in borehole replacement and arrangements to blend high and low nitrate waters. Future capital costs are estimated as 37m pounds over the next 20 years. The European Economic Community (EEC) Drinking Water Directive (80/778/EEC) sets a maximum admissible concentration of 50 mg litre(-1) nitrate. Adherence to this standard will cost 199m pounds over the same period.     

Metal behaviour in an estuary polluted by acid mine drainage: the role of particulate matter

The concentrations of dissolved and suspended particulate Cd, Cu and Zn have been determined in water samples obtained during two axial transects of the Rio Tinto-Huelva Ria system in south-west Spain, which is severely impacted by acid mine drainage. Although the metal concentrations in both phases were elevated, dissolved metals were dominant and, in the upper estuary, constituted > 99% of total metal in the water column. Dissolved metals behaved non-conservatively on each transect, with maximum concentrations in the low salinity region. There was no evidence of metal adsorption within the turbidity maximum zone, despite the high specific surface areas of resuspending particles. Measurements of electrophoretic mobility showed that the suspended particulate matter (SPM) had a positive surface charge in the salinity range 0-4, where the waters had a pH < 3. Desorption experiments were carried out in which SPM from the turbidity maximum zone was resuspended in coastal seawater. The desorption of the metals was monitored for 24 h, using anodic stripping voltammetry (ASV) to detect the variation in total dissolved Cd, Cu and Zn and the species of Cu and Zn. Total dissolved Cd concentrations doubled during the incubation period, whereas the concentration of total dissolved Cu declined and that of Zn remained rather constant. The ASV-labile fraction of dissolved Cu and Zn showed an initial sharp release followed by a slower uptake. However, desorption was shown to be a minor source of dissolved metals and made little contribution to the non-conservative behaviour in the low salinity zone. The results are used to predict the effects of acid mine drainage on estuarine ecology.     

Integration of natural behavior in housing systems

This paper deals with how the natural behavior of animals kept for production can be integrated when planning new housing systems or making changes to existing housing systems. Natural behavior can be defined as the repertoire of different behaviors animals show when kept in environments where they can carry out behaviors created in the evolutionary process. Motivation and innate behaviors are important aspects of natural behavior, and hindering them may lead to abnormal behavior and stress. One should first get a basic knowledge about the species-specific behavior in the wild or a seminatural environment. Thereafter, key stimuli and key features for normal behavior should be worked out, where after a reduction in space, development of a pen, scientific testing, modification, and finally testing the function in a larger scale should be carried out. Examples of housing of calves during the milk period and housing of sows around farrowing are given.     

Die Sinneszellen der Wirbeltiernetzhaut

Vertebrate visual cells represent a system in an extraordinarily dynamic state. Major parts of the photoreceptors are continually degraded and resynthesized, thus, the cell's morphological and functional integrity is maintained. Some components of visual cell renewal processes follow an endogenous, circadian rhythm driven by an ocular oscillator. Regulative mechanisms of these circadian rhythms may comprise interactions between the neurohormone melatonin and the putative retinal neurotransmitter and neuromodulator dopamine.     

Septic tank and agricultural non‐point source pollution within a rural watershed

This investigation addresses the problem of Non‐Point Source (NPS) pollution in the rural Lake Weatherford watershed in Parker County, Texas. This reservoir is the primary municipal water supply for the City of Weatherford, Texas. The principal method of wastewater disposal is the on‐site system or septic tanks for the small residential areas surrounding the reservoir.

Sources of NPS pollution of interest in this watershed include agricultural operations as well as the residential areas. These sites were identified with the aid of aerial photography and field investigation. Suspected NPS problems were substantiated through a sampling program involving chemical and biological testing of the reservoir. Results indicate that there is significant NPS pollution contamination of Lake Weatherford from agricultural sources and seepage from on‐site wastewater disposal systems. Excessive fecal coliform and fecal streptococcus counts (>500 bacteria/100 ml) were generally associated with rainfall events and several samples showed values > 100000 bacteria/100 ml. The fecal coliform/fecal streptococcus ratios indicated contamination from human sources, animal sources, and a combination of both. Nutrient concentrations fluctuated from quite low to high with ammonia as the most consistent problem. High ammonia values were also associated with rainfall events.     

Work characteristics,challenge appraisal,creativity, and proactive behavior: A multi‐level study

Work characteristics such as time pressure and job control can be experienced as a challenge that is positively associated with performance‐related behaviors. Using experience‐sampling data from 149 employees, we examined the relationships between these work characteristics and creativity and proactive behavior on a daily level. Results from multilevel analyses indicate that time pressure and job control are perceived as challenging, and that challenge appraisal in turn is related to daily creativity and proactive behavior. Furthermore, cross‐level mediation analyses revealed that daily work characteristics act as the mechanism underlying the relationships between chronic work characteristics and challenge appraisal. This study supports the view of time pressure as a challenge‐related stressor that leads to favorable outcomes. Copyright © 2009 John Wiley & Sons, Ltd.     

Temporal variability in dynamic and colloidal metal fractions determined by high resolution in situ measurements in a UK estuary

In recent environmental legislation, such as the Water Framework Directive in the European Union (WFD, 2000/60/EC), the importance of metal speciation and biological availability is acknowledged, although analytical challenges remain. In this study, the Voltammetric In situ Profiler (VIP) was used for high temporal resolution in situ metal speciation measurements in estuarine waters. This instrument simultaneously determines Cd, Cu and Pb species within a size range (ca. <4 nm) that is highly relevant for uptake by organisms. The colloidal metal fraction can be quantified through a combination of VIP measurements and analyses of total dissolved metal concentrations.VIP systems were deployed over tidal cycles in a seasonal study of metal speciation in the Fal Estuary, southwest England. Total dissolved concentrations were 4.97-315 nM Cu, 0.13-8.53 nM Cd and 0.35-5.75 nM Pb. High proportions of Pb (77 ± 17%) and Cu (60 ± 25%) were present as colloids, which constituted a less important fraction for Cd (37 ± 30%). The study elucidated variations in the potentially toxic metal fraction related to river flow, complexation by organic ligands and exchanges between dissolved and colloidal phases and the sediment. Based on published toxicity data, the bioavailable Cu concentrations (1.7-190 nM) in this estuary are likely to severely compromise the ecosystem structure and functioning with respect to species diversity and recruitment of juveniles. The study illustrates the importance of in situ speciation studies at high resolution in pursuit of a better understanding of metal (bio)geochemistry in dynamic coastal systems.     

Availability and properties of materials for the Fakse Landfill biocover

Methane produced in landfills can be oxidized in landfill covers made of compost; often called biocovers. Compost materials originating from seven different sources were characterized to determine their methane-oxidizing capacity and suitability for use in a full-scale biocover at Fakse Landfill in Denmark. Methane oxidation rates were determined in batch incubations. Based on material availability, characteristics, and the results of batch incubations, five of the seven materials were selected for further testing in column incubations. Three of the best performing materials showed comparable average methane oxidation rates: screened garden waste compost, sewage sludge compost, and an unscreened 4-year old garden waste compost (120, 112, and 108 g m⁻² d⁻¹, respectively). On the basis of these results, material availability and cost, the unscreened garden waste compost was determined to be the optimal material for the biocover. Comparing the results to criteria given in the literature it was found that the C/N ratio was the best indicator of the methane oxidation capacity of compost materials. The results of this work indicate that batch incubations measuring methane oxidation rates offer a low-cost and effective method for comparing compost sources for suitability of use in landfill biocovers.