Characterising and Understanding the Impact of Microbial Biofilms and the Extracellular Polymeric Substance (EPS) Matrix in Drinking Water Distribution Systems

Drinking water quality deteriorates during transportation through drinking water distribution systems (DWDS). Microbial activity and ecology, particularly within biofilms that occur on the inner-pipe surface of DWDS, are emerging as important drivers in the degradation process. Yet, we have little real-world applicable understanding of the DWDS biofilms. This paper provides a critical discussion of current drinking water biofilm research, highlighting the importance of biofilms, including the extracellular polymeric substances (EPS) and their interactions with the physico-chemical environment. Evidence is presented that the tools for biofilm analysis are becoming more accessible and there is now the opportunity to translate microbial research from idealised bench-top settings to practical real-world applications. It is essential that we understand biofilms and manage them within ageing, deteriorating DWDS infrastructure to protect public health and wellbeing

Impacts of water pH on the toxicity of fluoxetine on Daphnia magna: a multi-generational study

Fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI), has been widely prescribed as anti-depressant. While FLX has been frequently detected in surface waters, sediments and biota, only limited information is available on its in vivo toxicity, particularly in invertebrates, under changing water pH. In the present study, the ecotoxicity of FLX (pKa = 9.8) was investigated in different pH levels (6.8, 8.3, and 9.2) using Daphnia magna. Daphnia neonates ( (F0) were exposed to 0, solvent control, 31.3, 62.5, 125, 250, 500, or 1000 μg/L for 48 hr and its effects on survivals (EC20, 50 and 75) were determined. Moreover, Daphnia neonates (The first brood daphnids from the chronic tests were discarded and the second brood daphnids (F1) were employed for the multigenerational acute test within 12 hours. F1 neonates were further exposed to 0, solvent control, 31.3, 62.5, 125, 250, or 500 μg/L for 48 hr and their survivals (EC20, 50 and 75) were determined. F0 juveniles exposed to 0 or 55.6 μg/L at 10 d were measured for MDA. After 48 hr of F0 and F1 exposure, the EC50 significantly decreased (p < 0.05) at 6.17 μg/L of FLX at all tested pHs. Moreover, after 21 d F0 exposure, the reproduction showed an increasing trend until 55.6 μg/L and significantly decreased at 166.7 μg/L at pH 9.2. F1 neonates showed significantly decreased body length after 21 d exposure to 2.06, 6.17, 18.5 and 55.6 μg/L at pH 9.2. Malformation of F1 daphnids development was also observed at 2.06 μg/L to 500 μg/L. MDA concentration was also demonstrated increasing trends in all pHs and significantly increased at 55.6 μg/L at pH 6.8 and 9.2. Our observation clearly indicates that survival, reproduction, and growth performance in aquatic invertebrate can be adversely affected by FLX and the toxicity increases as water pH increases. A greater amount of uncharged ions from FLX has increased Reactive Oxidative Stress (ROS), MDA, by the ionic speciation at higher pH. Increased MDA concentration affected the mortality of F0 daphnids. Increased F1 daphnids population demonstrated significantly greater toxicity. As a result, the toxicity of FLX has increased acutely, chronically, and multigenerational effects by increasing pH levels. Consequences of longer-term exposure over multigenerations warrant further investigation

Uncertainties of size measurements in electron microscopy characterization of nanomaterials in foods

Electron microscopy is a recognized standard tool for nanomaterial characterization, and recommended by the European Food Safety Authority for the size measurement of nanomaterials in food. Despite this, little data have been published assessing the reliability of the method, especially for size measurement of nanomaterials characterized by a broad size distribution and/or added to food matrices. This study is a thorough investigation of the measurement uncertainty when applying electron microscopy for size measurement of engineered nanomaterials in foods. Our results show that the number of measured particles was only a minor source of measurement uncertainty for nanomaterials in food, compared to the combined influence of sampling, sample preparation prior to imaging and the image analysis. The main conclusion is that to improve the measurement reliability, care should be taken to consider replications and matrix removal prior to sample preparation

ASSESSING IMPACTS OF ENVIRONMENTAL CHANGE ON ABORIGINAL PEOPLE: AN ECONOMIC EXAMINATION OF SUBSISTENCE RESOURCE USE AND VALUE

The report describes the research design, data collection and preliminary analysis of an economic assessment of non-timber resource use by Aboriginal People in Northwest Saskatchewan. The project is designed to develop methods of valuing resource use by Aboriginal People so that these values can be incorporated into forest resource management decisions and to evaluate the impact of forest management actions on the economic well-being of Aboriginal People living in the region. Data on non-timber resource use are collected and spatially explicit economic models are developed in order to construct estimates of behavioral change and value associated with changes in the environment and landscape (through forestry, access, or other landscape changes).Environmental Economics and Policy, Resource /Energy Economics and Policy,

Prevalence of sulfonamide resistance genes in bacterial isolates from manured agricultural soils and pig slurry in the United Kingdom

Prevalence of three sulfonamide resistance genes, sul1, sul2 and sul3 and sulfachloropyridazine (SCP) resistance was determined in bacteria isolated from UK manured agricultural clay soils and slurry samples, over a two year period. Slurry from tylosin-fed pigs amended with SCP and oxytetracycline (OTC) was used for manuring. Sul gene positive isolates were further screened for the presence of class 1 and 2 integrons. Phenotypic resistance to SCP was significantly higher in pig slurry and post application soil than in pre-application soil. Of 5isolates, 23 % carried sul1, 18 % sul2 and 9 % sul3 only. Two percent of isolates contained all three sul genes. Class 1 and class 2 integrons were identified in 5 % and 11.7 % of sul positive isolates. In previous reports, sul1 was linked to class 1 integrons, but in this study only 8 % of sul1 positive isolates carried the intI1 gene. Sulfonamide resistant pathogens were identified in slurry amended soil and soil leachate, including Shigella flexneri, Aerococcus spp. and Acinetobacter baumanni, suggesting a potential environmental reservoir. Sulfonamide resistance in Psychrobacter, Enterococcus and Bacillus spp. is reported for the first time, and this study also provides the first description of the genotype sul1, sul2 and sul3 outside the Enterobacteriacae, and in the soil environment

Ruthenium volatilisation from reprocessed spent nuclear fuel - Studying the baseline thermodynamics of Ru(III)

Ruthenium is a fission product possessed of two relatively long lived isotopes, Ru and Ru, both of which form part of the Highly Active (HA) waste raffinate during spent nuclear fuel reprocessing. During reprocessing ruthenium, which may be in the form of the RuNO+ complex, encounters temperatures conducive to volatilization. Due rutheium's high specific radioactivity it is important to understand the mechanism by which volatilisation occurs. Here we use combined CV, RDE and electrochemical microgravimetry experiments in a study of the the RuCl3 system for the first time. We do this in the interest of establishing NO-free Ru(III) baseline behaviour so as to support future studies on NO complexed ruthenium. Using wide aqueous solvent window carbon electrodes we have observed discrete oxidations to a solution phase Ru(III)-Ru(IV)-Ru(III) trimer, to solid RuO2 and volatile RuO4. We have also observed and assigned discrete reductions of solid RuO2 back to Ru(III) and Ru(III) reduction to ruthenium metal

Quantity and Quality Benefits of in-Service Invasive Cleaning of Trunk Mains

Trunk mains are high risk critical infrastructure where poor performance can impact on large numbers of customers. Both quantity (e.g. hydraulic capacity) and quality (e.g. discolouration) of trunk main performance are affected by asset deterioration in the form of particle accumulation at the pipe wall. Trunk main cleaning techniques are therefore desirable to remove such material. However, little is quantified regarding the efficacy of different maintenance interventions or longer-term changes following such cleaning. This paper presents an assessment of quantity and quality performance of a trunk main system pre, post and for 12 months following cleaning using pigging with ice slurry. Hydraulic calibration showed a 7 times roughness height reduction after ice slurry pigging, evidencing substantially improved hydraulic capacity and reduced headloss. Turbidity response due to carefully imposed shear stress increase remained significant after the cleaning intervention, showing that relatively loose material had not been fully removed from the pipe wall. Overall the results demonstrate that cleaning by pigging with ice slurry can be beneficial for quantity performance, but care and further assessment may be necessary to realise the full quality benefits

Integron prevalence and diversity in manured soil

Integron abundance and diversity were studied in soil amended with pig slurry. Real-time PCR illustrated a significant increase in class 1 integron prevalence post slurry-application with increased prevalence still evident at 10 months post-application. Culture dependent data revealed 10 genera, including putative human pathogens, carrying class 1 and 2 integrons

Ensemble decision tree models using RUSBoost for estimating risk of iron failure in drinking water distribution systems

Safe, trusted drinking water is fundamental to society. Discolouration is a key aesthetic indicator visible to customers. Investigations to understand discolouration and iron failures in water supply systems require assessment of large quantities of disparate, inconsistent, multidimensional data from multiple corporate systems. A comprehensive data matrix was assembled for a seven year period across the whole of a UK water company (serving three million people). From this a novel data driven tool for assessment of iron risk was developed based on a yearly update and ranking procedure, for a subset of the best quality data. To avoid a ‘black box’ output, and provide an element of explanatory (human readable) interpretation, classification decision trees were utilised. Due to the very limited number of iron failures, results from many weak learners were melded into one high-quality ensemble predictor using the RUSBoost algorithm which is designed for class imbalance. Results, exploring simplicity vs predictive power, indicate enough discrimination between variable relationships in the matrix to produce ensemble decision tree classification models with good accuracy for iron failure estimation at District Management Area (DMA) scale. Two model variants were explored: ‘Nowcast’ (situation at end of calendar year) and ‘Futurecast’ (predict end of next year situation from this year’s data). The Nowcast 2014 model achieved 100% True Positive Rate (TPR) and 95.3% True Negative Rate (TNR), with 3.3% of DMAs classified High Risk for un-sampled instances. The Futurecast 2014 achieved 60.5% TPR and 75.9% TNR, with 25.7% of DMAs classified High Risk for un-sampled instances. The output can be used to focus preventive measures to improve iron compliance