A non-invasive acoustical method to measure the mean roughness height of the free surface of a turbulent shallow water flow.

In this paper, the directivity of the airborne sound field scattered by a dynamically rough free flow surface in a flume is used to determine the mean roughness height for six hydraulic conditions in which the uniform depth of the turbulent flow. The nonlinear curve fitting method is used to minimize the error between the predicted directivity and directivity data. The data fitting algorithm is based on the averaged solution for the scattered sound pressure as a function of angle which is derived through the Kirchhoff integral and its approximations. This solution takes into account the directivity of the acoustic source. For the adopted source and receiver geometry and acoustic frequency it is shown that the contribution from the stationary phase point (single specular point on the rough surface) yields similar results to those which can be obtained through the full Kirchhoff's integral. The accuracy in the inverted mean roughness height is comparable to that achieved with an array of conductive wave probes. This method enables non-invasive estimation of the flow Reynolds number and uniform flow depth.

Rapid detection of sewer defects and blockages using acoustic-based instrumentation.

Sewer flooding incidents in the UK are being increasingly associated with the presence of blockages. Blockages are difficult to deal with as although there are locations where they are more likely to occur, they do occur intermittently. In order to manage sewer blockage pro-actively sewer managers need to be able to identify the location of blockages promptly. Traditional closed-circuit television (CCTV) inspection technologies are slow and relatively expensive so are not well suited to the rapid inspection of a network. This is needed if managers are to be able to address sewer blockages proactively. This paper reports on the development of an acoustic-based sensor. The sensor was tested in a full scale sewer pipe in the laboratory and it was shown that it is able to find blockages and identify structural aspects of a sewer pipe such as a manhole and lateral connection. Analysis of the received signal will locate a blockage and also provide information on its character. The measurement is very rapid and objective and so inspections can be carried out at much faster rates than using existing CCTV technologies.

Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification, processing and production of Se-enriched food.

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30ng/g in white flour and 35ng/g in wholemeal flour from untreated plots up to >1800ng/g in white and >2200ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10g/ha increased total selenium in white and wholemeal bread by 155 and 185ng/g, respectively, equivalent to 6.4 and 7.1µg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65-87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.

Towards quantification of uncertainty in predicting water quality failures in integrated catchment model studies.

This paper describes the development and application of a method for estimating uncertainty in the prediction of sewer flow quantity and quality and how this may impact on the prediction of water quality failures in integrated catchment modelling (ICM) studies. The method is generic and readily adaptable for use with different flow quality prediction models that are used in ICM studies. Use is made of the elicitation concept, whereby expert knowledge combined with a limited amount of data are translated into probability distributions describing the level of uncertainty of various input and model variables. This type of approach can be used even if little or no site specific data is available. Integrated catchment modelling studies often use complex deterministic models. To apply the results of elicitation in a case study, a computational reduction method has been developed in order to determine levels of uncertainty in model outputs with a reasonably practical level of computational effort. This approach was applied to determine the level of uncertainty in the number of water quality failures predicted by an ICM study, due to uncertainty associated with input and model parameters of the urban drainage model component of the ICM. For a small case study catchment in the UK, it was shown that the predicted number of water quality failures in the receiving water could vary by around 45% of the number predicted without consideration of model uncertainty for dissolved oxygen and around 32% for unionised ammonia. It was concluded that the potential overall levels of uncertainty in the ICM outputs could be significant. Any solutions designed using modelling approaches that do not consider uncertainty associated with model input and model parameters may be significantly over-dimensioned or under-dimensioned. With changing external inputs, such as rainfall and river flows due to climate change, better accounting for uncertainty is required.

Prioritizing micronutrients for the purpose of reviewing their requirements: a protocol developed by EURRECA.

BACKGROUND: The EURRECA (EURopean micronutrient RECommendations Aligned) Network of Excellence (http://www.eurreca.org) is working towards the development of aligned recommendations. A protocol was required to assign resources to those micronutrients for which recommendations are most in need of alignment. METHODS: Three important 'a priori' criteria were the basis for ranking micronutrients: (A) the amount of new scientific evidence, particularly from randomized controlled trials; (B) the public health relevance of micronutrients; (C) variations in current micronutrient recommendations. A total of 28 micronutrients were included in the protocol, which was initially undertaken centrally by one person for each of the different population groups defined in EURRECA: infants, children and adolescents, adults, elderly, pregnant and lactating women, and low income and immigrant populations. The results were then reviewed and refined by EURRECA's population group experts. The rankings of the different population groups were combined to give an overall average ranking of micronutrients. RESULTS: The 10 highest ranked micronutrients were vitamin D, iron, folate, vitamin B12, zinc, calcium, vitamin C, selenium, iodine and copper. CONCLUSIONS: Micronutrient recommendations should be regularly updated to reflect new scientific nutrition and public health evidence. The strategy of priority setting described in this paper will be a helpful procedure for policy makers and scientific advisory bodies.

In-sewer sedimentation associated with active flow control.

Active flow control using automated gates and weirs aims to utilise available dispersed storage within sewer systems to alleviate the severity and frequency of localised flooding incidents. Whilst a previous study has demonstrated its potential, a key operational concern before implementation was sedimentation. An experimental programme was designed to investigate the sediment deposition created when using a flow control device. Tests were also undertaken to examine the potential for rapid gate opening to flush away any resulting deposits. In catchments dominated by fine material in suspension, the use of an active flow control device can result in a uniformly thick deposit upstream of the gate. Rapid gate opening results in deposited material eroding in large sections starting at the gate and moving in an upstream direction. Granular sediment forms a series of discrete bedforms which are fairly uniform regardless of the flow conditions and a larger deposit further upstream. The potential for flushing granular deposits is limited and modification of the operation of the gate has shown little potential for increasing the effectiveness. Therefore, active flow control using a single downstream gate may only be suitable in systems with fine material moving in suspension during dry weather flow and not where there is significant granular sediment.

Estimation of uncertainty in long term combined sewer sediment behaviour predictions, a UK case study.

There are regulatory driven requirements for UK water companies to reduce the number of properties at risk of sewer flooding. One of the potential causes of sewer flooding is the presence of persistent sediment deposits in sewers. This is a common problem in many combined sewers. Although the regulation is risk based, there is a gap in current knowledge on how risk assessment is affected by the uncertainty in sewer solids behaviour prediction. This paper describes a UK case study exploring the possibility of estimating uncertainty in sewer sediment deposit level predictions, using Monte Carlo simulations combined with a response database.

Rapid sonic characterisation of sewer change and obstructions.

This paper reports on the development of a low-cost, rapidly deployable sensor for surveying live sewers for blockages and structural failures. The anticipated cost is an order of magnitude lower than current techniques. The technology is based on acoustic normal model decomposition, The instrument emits short coded acoustic signals which are reflected from any sewer wall defect. The acoustic signals can be short Gaussian pulses or longer sinusoidal sweeps and pseudo-random noise. The processing algorithms used on the reflected signal can predict the extent and geometry of the pipe deformation, and the locations and approximate size of common blockages. The effect of the water level on the frequency of the fundamental mode has also been investigated. It is shown that the technique can be adapted to work reliably in relatively large 600 mm diameter sewer pipes.

Reticulated platelets interfere with flow cytometric reticulocyte counts.

As part of an iron absorption study, we needed to accurately count reticulocytes in the peripheral blood of healthy human volunteers before measuring their enrichment with stable iron isotopes given in an oral dose. Recent studies have suggested the usefulness of reticulocyte counting by flow cytometry, through a combination of differential light scatter and measurement of the stoichiometric binding of thiazole orange (TO) to RNA within the maturing erythrocyte. Using this method we set out to improve the precision of our quantitative analysis by counting more cells, as reticulocytes normally comprise <2% of the red cell population. To ensure exclusion of other cell types, we identified WBCs and platelets with CD16+CD45- allophycocyanin and CD61- phycoerythrin, respectively. After removal of CD16(+) CD45(+) TO(+) WBCs and CD61(+) TO(-) platelets from analysis, the remaining cells were a combination of CD61(-) TO(-) erythrocytes, CD61(-) TO(+) reticulocytes and CD61(+) TO(+) reticulated platelets. Reticulocyte counts were lower after exclusion of CD61(+) TO(+) cells from analysis. They were similarly lower when erythrocyte precursors were positively identified through their glycophorin A expression and TO uptake. We conclude that it is necessary to exclude reticulated platelets from flow cytometric reticulocyte analysis.

Sewer system design moving into the 21st century--a UK perspective.

Change in external factors, such as environmental legislation and climate change, will mean the future of sewerage systems is likely to be different from the past. Combined sewerage systems comprise the vast majority of existing sewers in countries such as the UK. A study funded by UK Water Industry Research Ltd has reviewed the current state of sewerage within the UK, the likely drivers for change and the consequent future impacts over a 75 year timescale. Potential responses to address the anticipated changes have also been considered. It is concluded that due to the wide extent and value of existing sewer systems, these will continue to be used for the foreseeable future. However, in order to meet the major challenges as a result of changing external factors, these need to be operated more effectively, new ideas need to be explored and moves to develop better and more integrated water management systems need to be started if sewer systems in the UK are to provide the anticipated required levels of service well into the 21st century.

Improved formulations for rapid erosion of diverse solids in combined sewers.

For more than a decade, research carried out in Scotland has investigated the movement of sediment in sewers and the associated pollutant release. Pollution by discharges from combined sewer overflows can adversely affect watercourses, particularly those in urban areas. Solids and dissolved contaminants, many derived from in-sewer deposits during a storm event, can be especially significant. This phenomenon can occur during events known as 'foul flushes'. In combined sewers these typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants is significantly higher than at other times. It has become apparent that much of the suspended load originates from solids eroded from the bed. The 'near bed solids' which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions. This paper describes some of the methods employed to investigate the solids eroding in combined sewers during peak flow events. The work examined the potential for sediment re-suspension under high flow conditions both in the laboratory and in the field.

Estimation of iron absorption in humans using compartmental modelling.

OBJECTIVE: To evaluate whether a compartmental model could estimate iron absorption as accurately as the well-validated technique of plasma area under the curve using labelled test meals. DESIGN: The study is a randomised cross-sectional intervention. SETTING: The study was carried out at the Human Nutrition Unit at the Institute of Food Research, Norwich, UK. SUBJECTS: A total of nine female volunteers, aged 33+/-8 y. INTERVENTIONS: Volunteers were given an oral dose (approximately 5 mg) of Fe-57 as iron sulphate in an orange juice test drink and simultaneously infused Fe-58 (approximately 200 microg) as iron citrate over 90 min. Multiple blood samples were taken for the following 6 h. The samples were analysed by mass spectrometry and iron absorption was estimated using a mathematical model based on the appearance of Fe isotopes in plasma and the area under the curve technique. RESULTS: The geometric mean (-1 s.d., +1 s.d.) absorption of the model estimate is 16% (9, 31) and the area under curve estimate is 18% (8, 29). CONCLUSIONS: Results indicate that a compartmental model can be used to estimate labelled iron absorption although it is unlikely that this new method will be used in favour of an existing one. Further studies are now needed with unlabelled iron to assess whether the technique could have application in the assessment of total (haem+nonhaem) iron absorption from food.

Copper absorption from foods labelled intrinsically and extrinsically with Cu-65 stable isotope.

OBJECTIVE: To determine copper absorption from copper containing foods labelled either intrinsically or extrinsically with a highly enriched Cu-65 stable isotope label. DESIGN: A longitudinal cross-over study. SETTING: The study was conducted at the Institute of Food Research, Human Nutrition Unit, Norwich, UK. SUBJECTS: Subjects were recruited locally via advertisements placed around the Norwich Research Park. A total of 10 volunteers (nine female, one male) took part in the study, but not all volunteers completed each of the test meals. INTERVENTIONS: A highly enriched Cu-65 stable isotope label was administered to volunteers in the form of a reference dose or in breakfast test meals consisting of red wine, soya beans, mushrooms or sunflower seeds. Faecal monitoring and mass spectrometry techniques were used to estimate the relative quantities of copper absorbed from the different test meals. RESULTS: True copper absorption from the reference dose (54%) was similar to extrinsically labelled red wine (49%) and intrinsically labelled sunflower seeds (52%), but significantly higher than extrinsically labelled mushrooms (35%), intrinsically (29%) and extrinsically (15%) labelled soya beans and extrinsically labelled sunflower seed (32%) test meals. CONCLUSIONS: The use of Cu-65 extrinsic labels in copper absorption studies requires validation according to the food being examined; intrinsic and extrinsic labelling produced significantly different results for sunflower seeds.

Iron contents of Malawian foods when prepared in iron cooking pots.

The aim of this study was to determine the iron content of Malawian foods prepared in iron pots and to examine the effects of continuous cooking time and added oil on the iron content of the food prepared. Foods prepared, which included a staple (Nsima), relish vegetables, and beans, had an increased iron content when prepared in an iron compared to a glass pot. For these three foods, iron content per gram increased by 3.15 micrograms, 35.8 micrograms, and 147.32 micrograms, respectively. Continuous use of the iron pot for cooking could have a positive effect on the amount of iron added to the food, as the three foods' iron content increased by a further 2.9 micrograms iron/g, 7.6 micrograms iron/g and 20.1 micrograms iron/g, respectively. This effect needs more study. Food pH was significantly negatively correlated with food iron content. The use of oil reduced the amount of iron added to stir-fried vegetables by 52.37 micrograms/g and increased iron added to Nsima (1.2 micrograms/g). Malawian foods increased their iron content when cooked in iron pots. This method of food preparation potentially provides a low-cost sustainable means of improving the iron intakes of families and communities where this traditional method of food preparation is acceptable.

Validity and reproducibility of a computerised tool for assessing the iron, calcium and vitamin C intake of Belgian women.

OBJECTIVE: To determine the relative validity of a newly developed iron intake assessment tool, designed specifically to assess iron, calcium and vitamin C intake. DESIGN: Estimates of iron, calcium and vitamin C intake from a computerised iron intake assessment tool compared with those from 11-day estimated dietary records. SETTING: Region of Ghent (N= +/- 225,000), a city in Flanders, the Dutch-speaking part of Belgium. SUBJECTS: In all, 50 women aged 18-39 y, participating in a large-scale epidemiological study on iron intake and iron status. MAIN RESULTS: Mean dietary iron intake from the 11-day food record, the unadjusted dietary iron intake assessment tool and the adjusted tool was, respectively, 10.5 +/- 2.7, 10.4 +/- 4.3 and 9.6 +/- 2.9 mg. For the different nutrients, the correlation coefficients vary from 0.45 to 0.60 for adjusted intake. The mean difference of iron intake by the two methods (0.8 +/- 2.9 mg) did not differ significantly from zero. The new method correctly classified 38% (iron), 38% (calcium) and 58% (vitamin C) of the subjects to the correct tertile. The correlation coefficients ranged from 0.48 for adjusted vitamin C intake to 0.73 for adjusted calcium intake between two administrations. CONCLUSION: The newly developed instrument can be used to assess mean group intakes of iron, calcium and vitamin C in women consuming a Western diet. However, since the ranking capability of the new tool is rather weak, further refinement of the tool is required to produce a robust method for assessing iron, calcium and vitamin C intakes of individuals. SPONSORSHIP: This research was supported by the Belgian National Fund for Scientific Research/Flemish Division (Fund No G.0152.01).

Bioavailability of selenium from fish, yeast and selenate: a comparative study in humans using stable isotopes.

OBJECTIVE: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast. DESIGN: The intervention study was a parallel, randomised, reference substance controlled design carried out at two different centres in Europe. SETTING: The human study was carried out at the Institute of Food Research, Norwich, UK and at TNO Nutrition and Food Research, Zeist, The Netherlands. SUBJECTS: In all, 35 male volunteers aged 18-50 y were recruited; 17 subjects were studied in Norwich (UK) and 18 in Zeist (Netherlands). All of the recruited subjects completed the study. INTERVENTIONS: Biosynthetically labelled trout fish (processed by two different methods), biosynthetically labelled brewers yeast and isotopically labelled selenate were used to estimate selenium apparent absorption and retention by quantitative analysis of stable isotope labels recovered in faeces and urine. Subjects consumed the labelled foods in four meals over two consecutive days and absorption was measured by the luminal disappearance method over 10 days. Urinary clearance of isotopic labels was measured over 7 days to enable retention to be calculated. RESULTS: Apparent absorption of selenium from fish was similar to selenate and there was no difference between the two processing methods used. However, retention of fish selenium was significantly higher than selenate (P<0.001). Apparent absorption and retention of yeast selenium was significantly different (P<0.001) from both fish selenium and selenate. CONCLUSION: Fish selenium is a highly bioavailable source of dietary selenium. Cooking did not affect selenium apparent absorption or retention from fish. Selenium from yeast is less bioavailable.

Sewer sediment transport studies using an environmentally controlled annular flume.

This paper provides an overview and some preliminary results of a collaborative project recently completed at WL Delft Hydraulics. It describes tests in an annular flume, in which sediment deposits were formed under carefully controlled and monitored environmental conditions. The deposits were then subjected to a series of time steps in which the rotational speed of the flume's top and bottom plates was increased, progressively increasing the bed shear stress. The sediment deposits were formed using three different types of sediment. An artificial organic sediment, together with a uniformly sized sand were selected as surrogate sewer sediments. The deposits in the remaining experiments were real in-sewer sediments, from catchments in the UK (Dundee) and The Netherlands (Loenen). During the erosion test, total and volatile suspended solids concentration, particle size distribution of the eroded sediment, and COD and DO levels were recorded. The bed surface topography was also measured so that the influence of the deposit formation condition on bedforms could also be examined. Where bed consolidation times were least 24 hours a biologically active surficial layer was observed to develop at the sediment/water interface. The initial deposit conditions (temperature and deposit duration) were both found to have a significant impact on the subsequent erosion of the deposit.

The utilisation of engineered invert traps in the management of near bed solids in sewer networks.

Large existing sewers are considerable assets which wastewater utilities will require to operate for the foreseeable future to maintain health and the quality of life in cities. Despite their existence for more than a century there is surprisingly little guidance available to manage these systems to minimise problems associated with in-sewer solids. A joint study has been undertaken in the UK, to refine and utilise new knowledge gained from field data, laboratory results and Computational Fluid Dynamics (CFD) simulations to devise cost beneficial engineering tools for the application of small invert traps to localise the deposition of sediments in sewers at accessible points for collection. New guidance has been produced for trap siting and this has been linked to a risk-cost-effectiveness assessment procedure to enable system operators to approach in-sewer sediment management pro-actively rather than reactively as currently happens.

Use of stable isotopes to assess the bioavailability of trace elements: a review.

The bioavailability (utilization) of trace elements is very variable, depending on the characteristics of the element itself, composition of the diet, gastrointestinal conditions and other physiological factors. To derive dietary recommendations and make use of emerging information on diet-gene interactions relating to nutritional requirements for trace elements, methods for assessing bioavailability are required. The trace elements of particular interest include iron, zinc, selenium and copper because of problems of deficiency, purported links with chronic diseases, and the growing market in fortified foods and supplements. The absorption and subsequent metabolism of trace elements can be monitored using stable isotope tracers, but there are difficulties associated with this approach. Although radioisotopes offer many advantages over stable isotopes, their use is restricted due to safety and ethical issues. The difficulties and limitations of methodologies associated with labelling of trace elements in foods with stable isotopes, design of human studies to generate results that predict bioavailability, and detection and quantification of stable isotopes in biological samples are discussed.