The difference a day can make: The temporal dynamics of drinking water access and quality in urban slums

In urban slums – home to approximately 1 billion people worldwide - access to clean drinking water is woefully inadequate despite the United Nations' declaration that access to safe water is a fundamental human right. Households in slums are frequently forced to rely on multiple drinking water sources to meet their needs. Numerous factors influence choice of water source, including water quality, availability, reliability, and affordability. These factors are not temporally static, but instead vary over multiple timescales (from sub-daily changes to annual changes and beyond) in response to changes in the water source itself and changes in the household's ability to use that source. For example, the cost of water can may change over time in response to water availability (e.g. rainy season versus dry season) and a slum household's ability to pay for water may change over time in response to changes in household income. However, existing national and global monitoring of safe water access, including Sustainable Development Goal 6, overlook these temporal dynamics of water access, quality and health risk in slums. This paper proposes a research agenda for exploring temporal changes in drinking water access and quality in urban slums and their potential influence on health risk. It argues that in the design of research studies, policy interventions, and drinking water monitoring aimed at improving access and health in urban slums, temporal dynamics should be considered over at least three interlinked time scales: short-term (from sub-daily to week-to-week), medium-term (from month-to-month to season-to-season) and long-term (from year-to-year). The paper concludes with recommendations for future research on temporal dynamics of drinking water and health in slums

Plastic pollution as a novel reservoir for the environmental survival of the drug resistant fungal pathogen Candida auris

The WHO recently classified Candida auris as a fungal pathogen of "critical concern". Evidence suggests that C. auris emerged from the natural environment, yet the ability of this pathogenic yeast to survive in the natural environment is still poorly understood. The aim of this study, therefore, was to quantify the persistence of C. auris in simulated environmental matrices and explore the role of plastic pollution for facilitating survival and potential transfer of C. auris. Multi-drug resistant strains of C. auris persisted for over 30 days in river water or seawater, either planktonically, or in biofilms colonising high-density polyethylene (HDPE) or glass. C. auris could be transferred from plastic beads onto simulated beach sand, particularly when the sand was wet. Importantly, all C. auris cells recovered from plastics retained their pathogenicity; therefore, plastic pollution could play a significant role in the widescale environmental dissemination of this recently emerged pathogen.</p

The disparity between regulatory measurements of E. coli in public bathing waters and the public expectation of bathing water quality

The main objectives of the European Union (EU) Bathing Water Directive (BWD) 2006/7/EC are to safeguard public health and protect designated aquatic environments from microbial pollution. The BWD is implemented through legislation by individual EU Member States and uses faecal indicator organisms (FIOs) as microbial pollution compliance parameters to determine season-end bathing water classifications (either ‘Excellent’ ‘Good’ ‘Sufficient’ or ‘Poor’). These classifications are based on epidemiological studies that have linked human exposure to FIOs with the risk of contracting a gastrointestinal illness (GI). However, understanding public attitudes towards bathing water quality, together with perceptions of relative exposure risks, is often overlooked and yet critically important for informing environmental management decisions at the beach and ensuring effective risk communication. Therefore, this study aimed to determine the effectiveness of current regulatory strategies for informing beach users about bathing water quality, and to assess public understanding of the BWD classifications in terms of exposure risk and public health. Two UK designated bathing waters were selected as case studies, and questionnaires were deployed to beach-users. The bathing waters had different classification histories and both had electronic signage in operation for communicating daily water quality predictions. The majority of respondents did not recognise the standardised EU bathing water quality classification signs, and were unaware of information boards or the electronic signs predicting the water quality on that particular day. In general, respondents perceived the bathing water at their respective beach to be either ‘good’ or ‘sufficient’ which were also the lowest classifications of water quality they would be willing to accept for bathing. However, the lowest level of risk of contracting a gastrointestinal illness that respondents would be willing to accept suggested a significant misunderstanding of the BWD classification system, with the majority (91%) of respondents finding only a < 1% risk level acceptable. The ‘Good’ classification is much less stringent in terms of likelihood of GI. This study has shown that the current public understanding of the BWD classifications in terms of exposure risk and public health is limited, and an investment in methods for disseminating information to the public is needed in order to allow beach-users to make more informed decisions about using bathing waters

The seaweed fly (Coelopidae) can facilitate environmental survival and transmission of E. coli O157 at sandy beaches

The sustainable management of recreational beaches is essential for minimising risk of human exposure to microbial pathogens whilst simultaneously maintaining valuable ecosystem services. Decaying seaweed on public beaches is gaining recognition as a substrate for microbial contamination, and is a potentially significant reservoir for human pathogens in close proximity to beach users. Closely associated with beds of decaying seaweed are dense populations of the seaweed fly (Coelopidae), which could influence the spatio-temporal fate of seaweed-associated human pathogens within beach environments. Replicated mesocosms containing seaweed inoculated with a bioluminescent strain of the zoonotic pathogen E. coli O157:H7, were used to determine the effects of two seaweed flies, Coelopa frigida and C. pilipes, on E. coli O157:H7 survival dynamics. Multiple generations of seaweed flies and their larvae significantly enhanced persistence of E. coli O157:H7 in simulated wrack habitats, demonstrating that both female and male C. frigida flies are capable of transferring E. coli O157:H7 between individual wrack beds and into the sand. Adult fly faeces can contain significant concentrations of E. coli O157:H7, which suggests they are capable of acting as biological vectors and bridge hosts between wrack habitats and other seaweed fly populations, and facilitate the persistence and dispersal of E. coli O157:H7 in sandy beach environments. This study provides the first evidence that seaweed fly populations inhabiting natural wrack beds contaminated with the human pathogen E. coli O157:H7 have the capacity to amplify the hazard source, and therefore potential transmission risk, to beach users exposed to seaweed and sand in the intertidal zone. The risk to public health from seaweed flies and decaying wrack beds is usually limited by human avoidance behaviour; however, seaweed fly migration and nuisance inland plagues in urban areas could increase human exposure routes beyond the beach environment

Quantifying stakeholder understanding of an ecosystem service trade-off

Sustainable management of global natural resources is challenged by social and environmental drivers, adding pressure to ecosystem service provision in many regions of the world where there are competing demands on environmental resources. Understanding trade-offs between ecosystem services and how they are valued by different stakeholder groups is therefore critical to maximise benefits and avoid conflict between competing uses. In this study we developed a novel participatory trade-off experiment to elicit the perception of 43 participants, from across four key stakeholder groups, working in land and water management (Environmental Regulators, Farming Advisors, Water Industry Staff and Catchment Scientists). Using the Production Possibility Frontier (PPF) concept, we quantified stakeholder assessment of both the shape and the uncertainty around the PPF in a trade-off between agricultural intensity and the ecological health of freshwater systems. The majority of stakeholder groups selected threshold and logistic decay trade-off curves to describe the relationship of the trade-off, and estimated the uncertainty around the curves to be intermediate or large. The views of the four stakeholder groups differed significantly regarding how they estimated stakeholder trade-off prioritisation; the largest difference in perspectives was identified between Environmental Regulators and Farm Advisors. The methodology considered the cultural, socio-economic and institutional specificities of an ecosystem service interaction and identified potential sources of conflict but also possible solutions for win-win opportunities to explore and share understanding between stakeholders. Valuing stakeholder knowledge as a form of expert data and integrating this into participatory decision-making processes for land and water management thus contributes considerable value beyond traditional approaches to ecosystem service assessments

Specific Heat of the Dilute Ising Magnet LiHox_xY1−x_{1-x}F4_4

We present specific heat data on three samples of the dilute Ising magnet \HoYLF with $x = 0.018$, 0.045 and 0.080. Previous measurements of the ac susceptibility of an $x = 0.045$ sample showed the Ho$^{3+}$ moments to remain dynamic down to very low temperatures and the specific heat was found to have unusually sharp features. In contrast, our measurements do not exhibit these sharp features in the specific heat and instead show a broad feature, for all three samples studied, which is qualitatively consistent with a spin glass state. Integrating $C/T$, however, reveals an increase in residual entropy with lower Ho concentration, consistent with recent Monte Carlo simulations showing a lack of spin glass transition for low x.Comment: 10 pages, 3 figurs, accepted for publication in Phys. Rev. Let

Impact of low intensity summer rainfall on E. coli-discharge event dynamics with reference to sample acquisition and storage

Understanding the role of different rainfall scenarios on faecal indicator organism (FIO) dynamics under variable field conditions is important to strengthen the evidence base on which regulators and land managers can base informed decisions regarding diffuse microbial pollution risks. We sought to investigate the impact of low intensity summer rainfall on Escherichia coli-discharge (Q) patterns at the headwater catchment scale in order to provide new empirical data on FIO concentrations observed during baseflow conditions. In addition, we evaluated the potential impact of using automatic samplers to collect and store freshwater samples for subsequent microbial analysis during summer storm sampling campaigns. The temporal variation of E. coli concentrations with Q was captured during six events throughout a relatively dry summer in central Scotland. The relationship between E. coli concentration and Q was complex with no discernible patterns of cell emergence with Q that were repeated across all events. On several occasions, an order of magnitude increase in E. coli concentrations occurred even with slight increases in Q, but responses were not consistent and highlighted the challenges of attempting to characterise temporal responses of E. coli concentrations relative to Q during low intensity rainfall. Cross-comparison of E. coli concentrations determined in water samples using simultaneous manual grab and automated sample collection was undertaken with no difference in concentrations observed between methods. However, the duration of sample storage within the autosampler unit was found to be more problematic in terms of impacting on the representativeness of microbial water quality, with unrefrigerated autosamplers exhibiting significantly different concentrations of E. coli relative to initial samples after 12-h storage. The findings from this study provide important empirical contributions to the growing evidence base in the field of catchment microbial dynamics

Dimensional Evolution of Spin Correlations in the Magnetic Pyrochlore Yb2Ti2O7

The pyrochlore material Yb2Ti2O7 displays unexpected quasi-two-dimensional (2D) magnetic correlations within a cubic lattice environment at low temperatures, before entering an exotic disordered ground state below T=265mK. We report neutron scattering measurements of the thermal evolution of the 2D spin correlations in space and time. Short range three dimensional (3D) spin correlations develop below 400 mK, accompanied by a suppression in the quasi-elastic (QE) scattering below ~ 0.2 meV. These show a slowly fluctuating ground state with spins correlated over short distances within a kagome-triangular-kagome (KTK) stack along [111], which evolves to isolated kagome spin-stars at higher temperatures. Furthermore, low-temperature specific heat results indicate a sample dependence to the putative transition temperature that is bounded by 265mK, which we discuss in the context of recent mean field theoretical analysis.Comment: 5 pages, 6 figure

Juxtaposition of Spin Freezing and Long Range Order in a Series of Geometrically Frustrated Antiferromagnetic Gadolinium Garnets

Specific heat measurements in zero magnetic field are presented on a homologous series of geometrically frustrated, antiferromagnetic, Heisenberg garnet systems. Measurements of Gd3Ga5O12, grown with isotopically pure Gd, agree well with previous results on samples with naturally abundant Gd, showing no ordering features. In contrast, samples of Gd3Te2Li3O12 and Gd3Al5O12 are found to exhibit clear ordering transitions at 243 mK and 175 mK respectively. The effects of low level disorder are studied through dilution of Gd3+ with non-magnetic Y3+ in Gd3Te2Li3O12. A thorough structural characterization, using X-ray diffraction, is performed on all of the samples studied. We discuss possible explanations for such diverse behavior in very similar systems.Comment: Accepted for publication in Physical Review