92 research outputs found
Springtime benthic fluxes in the Salish Sea: Environmental parameters driving spatial variation in the exchange of dissolved oxygen, inorganic carbon, nutrients, and alkalinity between the sediments and overlying water
Recent decades have seen changes to biogeochemical cycles in the Salish Sea, including alterations in water column nutrients, an expansion of hypoxic zones, and bottom water acidification. Marine sediments can be a major contributor to these biogeochemical cycles by exchanging solutes with bottom water. In an effort to understand the sediment biogeochemistry of the Salish Sea further, benthic fluxes of dissolved oxygen (DO), dissolved inorganic carbon (DIC), pH, total alkalinity (TA), and nutrients (ammonium, nitrate+nitrite, phosphate, silicate) between the sediment and the overlying water were directly measured using incubated flux cores at 42 sites in April and early May 2018. Explanatory variables describing bottom water conditions (salinity, temperature, DO, DIC, pH, and TA), sediment properties (grain size, total organic carbon, and C:N ratio), and site depth at the time of sampling were also collected. Denitrification estimates for each station were made using the benthic fluxes and estimates of C:N ratios of organic matter suspended in bottom water near each station.
Benthic fluxes varied considerably across the Salish Sea and high variability was observed between core replicates. In general, DO fluxes were larger than DIC fluxes and we attributed this to the oxidation of reduced compounds stored in sediments. The ratio phosphorus to DIC fluxes were less than the Redfield ratio, indicating phosphorus storage in the sediments. At all but two sites denitrification was present, with a median rate of 1 mmol m-2 d-1. Using canonical redundancy analysis, the spatial variation observed in benthic fluxes and denitrification rates was determined to be primarily driven by water column depth and bottom water DO.
Spatial variation was also observed in the estimations of sediment contribution to water column biogeochemistry in Puget Sound basins. Denitrification rates were estimated to remove 11% of the dissolved inorganic nitrogen (DIN) supplied to the bottom water in Hood Canal, while in the Central Basin only 1% was removed. This difference was due to the long bottom water residence time in Hood Canal, where the denitrification can have a larger impact on bottom water DIN concentrations as the water slowly moves through the basin. Nearly all of the particulate phosphorus that reached the seafloor during the early spring was estimated to be stored in the sediment. Sediment oxygen uptake was found to account for approximately 80% of the bottom water DO removal in the South Basin compared to 21 – 35% in the other basins. The sediments play a large role in the South Basin because it is shallow.
This spatial study illuminates the varying contributions that sediments make to the functioning of Salish Sea biogeochemistry. Seasonal benthic flux measurements should be made to further understand and quantify the influence that sediments have on water column biogeochemistry in the Salish Sea
Measuring the high redshift space density of FRI radio galaxies: investigating the nature of the FRI/II divide
The results are presented here of multi-wavelength observations
centred on two fields of the Leiden-Berkeley Deep Survey, which form the basis
for a study of the population and cosmic evolution of the high
redshift, low power, Fanaroff & Riley class I (FRI) radio galaxies.
These fields, Hercules.1 and Lynx.2, contain a complete sample of 81
radio sources with S_1.4GHz > 0.5 mJy within 0.6 square
degrees. Wide-field, ~1.5 arcsec resolution, radio observations,
along with near infra-red and optical imaging, and some multi-object
spectroscopy, are used to select the best high-redshift FRI
candidates, giving 37 in total. Currently, the host galaxy
identification fraction is 86% with 11
sources remaining unidentified at a level of r > 25.2
(Hercules; 4 sources) or r > 24.4 (Lynx; 7 sources) and
K > 20. Spectroscopic redshifts are determined for
49% of the sample and photometric redshift estimates are presented for the
sample sources without spectra or previously published results.95% of the 37 best FRI high-redshift candidate sources were then observed using
sub-arcsecond radio resolution, with the aim of detecting extended
emission with respect to compact core features - vital for
unambiguous morphological classification. The nature of the radio
observations meant that 10 extra sample sources could also be included
in the data. Lower resolution data were also taken
for the Lynx.2 field sources to provide a comparison with the
1.5 arcsec data.The classification of the entire radio sample is done in two
stages. Sources which showed clear extension are classified by
morphology alone, whereas sources with no obvious or weak extension
were classified using a combination of morphology and flux density
loss in the higher resolution data indicative of resolved out extended emission. Five
groups are used for this - `Certain FRIs', `Likely FRIs', `Possible FRIs', `Unclassifiable
sources' (for those not included in the higher resolution
observations) and `Not FRIs'. The final group numbers are 8, 10, 24,
33 and 6 for groups 1-5 respectively.The space densities of the maximum, probable and minimum FRIs are then
calculated and compared to two previously published measurements of the
local value, and with the behaviour of the strongest FRII sources. The results
for all three groups show density enhancements of factors of 5-9 at
z ~ 1.0 which implies cosmic evolution of the FRI population; this
enhancement is also in very good agreement with that predicted by previous
models. The behaviour of the FRI/FRII dividing luminosity, as a
function of host galaxy absolute magnitude, at the different cosmic
epochs of the sample, and for two different star formation histories,
is also investigated. A shift to brighter absolute magnitudes is found
to be inconsistent with the data but this conclusion is weak due to
the lack of knowledge of the host galaxy stellar populations, and the
small number of sources in the sample
Fashion Design and Laundry Practices: Practice-Orientated Approaches to Design for Sustainability
This doctoral enquiry develops practice-orientated approaches to design for sustainability. It focuses on the relationship between garment design, laundry practices and sustainability, and responds to research that evidences domestic laundering as one of the most environmentally damaging stages in a garment’s lifecycle (Allwood, et al.,2006; Hansen, et al., 2007).
A one-year laundry study surveyed the use and laundry of sixteen garments to ascertain the relationship between garment design and laundry behaviour. The research findings revealed that laundry behaviours are complex and unpredictable, and often not directly linked to producing cleaner clothes. Laundry routines are underpinned by factors beyond cleanliness including: garment use, social auditing, garment aesthetics,life stage, cultural norms, and spatial arrangements within the household.
Through re-examining laundry as a social practice the research develops a series of design provocations to challenge the organisation of laundry practices, and by extension the frequencies and processes in which laundry is carried out. The findings highlight that understanding laundry as a social practice opens a space to reconceptualise design, laundry behaviour and sustainability. It decentres material products and attends to the embedded social dynamics that are set within a nexus of spaces, materials, thoughts, actions and emotions. This provides an alternative lens from which to view and develop design theories and practice for sustainability in fashion. The central insight from the research shows there are multiple benefits from incorporating social theory into methodologies for design for sustainability
Stick or twist? Career decision-making during contractual uncertainty for NHS junior doctors
OBJECTIVES: To examine the extent, and nature, of impact on junior doctors' career decisions, of a proposed new contract and the uncertainty surrounding it. DESIGN: Mixed methods. Online survey exploring: doctors' future training intentions; their preferred specialty training (ST) programmes; whether they intended to proceed immediately to ST; and other plans. Linked qualitative interviews to explore more fully how and why decisions were affected. SETTING: Doctors (F2s) in second year of Foundation School (FS) Programmes in England. PARTICIPANTS: Invitations sent by FSs. Open to all F2s November 2015-February 2016. All FSs represented. Survey completed by 816 F2s. Sample characteristics broadly similar to national F2 cohort. MAIN OUTCOME MEASURES: Proportions of doctors intending to proceed to ST posts in the UK, to defer or to exit UK medicine. Proportion of doctors indicating changes in training and career plans as a result of the contract and/or resulting uncertainty. Distribution of changes across training programmes. Explanations of these intentions from interviews and free text comments. RESULTS: Among the responding junior doctors, 20% indicated that issues related to the contract had prompted them to switch specialty and a further 20% had become uncertain about switching specialty. Switching specialty choice was more prevalent among those now choosing a community-based, rather than hospital-based specialty. 30% selecting general practice had switched choice because of the new contract. Interview data suggests that doctors felt they had become less valued or appreciated in the National Health Service and in society more broadly. CONCLUSIONS: Doctors reported that contract-related issues have affected their career plans. The most notable effect is a move away from acute to community-based specialities, with the former perceived as more negatively affected by the proposed changes. It is concerning that young doctors feel undervalued, and this requires further investigation
Investigating awareness, fear and control associated with norovirus and other pathogens and pollutants using best–worst scaling
Pollutants found in the water and air environment represent an ever-growing threat to human health. Contact with some air-, water- and foodborne pathogens (e.g. norovirus) results in gastrointestinal diseases and outbreaks. For future risk mitigation, we aimed to measure people’s awareness of waterborne and foodborne norovirus relative to other environment-associated pollutants (e.g. pesticides, bioaerosols, antibiotic resistant bacteria) and well-known risks (e.g. diabetes, dementia, terrorist attack). We used an online survey, which included a best–worst scaling component to elicit personal levels of control and fear prompted by norovirus relative to 15 other risks. There was a negative correlation between levels of fear vs. control for all 16 measured risks. Perceived infection control levels were higher amongst women compared to men and correlated with age and the level of qualification in both groups. Participants who had sought advice regarding the symptoms caused by norovirus appeared to have more control over the risks. Norovirus is associated with high levels of fear, however, the levels of control over it is low compared to other foodborne illnesses, e.g. Salmonella. Addressing this deficit in the public’s understanding of how to control exposure to the pathogen in an important health need
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