Evaluation of measured dissolved and bio-met predicted bioavailable Cu, Ni and Zn concentrations in runoff from three urban catchments

Urban runoff is a diffuse source of pollution contributing to the poor ecological and chemical status of surface waters. Whilst the EU Priority Hazardous Substances Directive now identifies environmental quality standards for selected metals in relation to the bioavailable metal fraction the relationship between analytically determined metal size fractions transported by urban runoff and the often variably defined concept of bioavailability has not been thoroughly evaluated. This paper provides a review of the terminology used within urban runoff studies to characterise metal fractions and behaviour. Measured dissolved and truly dissolved (determined by ultrafiltration; <3000 molecular weight cutoff) Cu, Ni, and Zn concentrations are also compared to the bioavailable metal fraction (as predicted using Bio-met, a simplified biotic ligand model) in snowmelt and rainfall derived runoff samples from three urban catchments. The study shows that predicted bioavailable concentrations were significantly lower than truly dissolved concentrations for all metals and discusses current bioavailability modelling parameters in relation to rainfall and snowmelt runoff data sets. Statistical analysis of relationships between field and predicted bioavailable data sets indicate that the bioavailable fractions originate from both colloidal and truly dissolved fractions

An assessment of gully pot sediment scour behaviour under current and potential future rainfall conditions

Gully pots actively trap sediments transported by urban runoff to prevent in-pipe blockages and surface flooding. However, due to poor maintenance (resulting in sediment build-up) and increasingly extreme wet weather events, the scour of previously-deposited sediments from gully pots is identified as a potential contributor to EU Water Framework Directive failure. While basal sediment scour deterministic models have been developed and validated using laboratory and field gully pot data sets, the ability of these models to predict behaviour at sites other than those for which they were established has not been addressed. Nor has the impact of future rainfall predictions on the role of gully pots as sediment sources been systematically examined. As a contribution to addressing these knowledge gaps, the performance of two gully pot basal sediment scour models of distinct complexity levels are evaluated under current and future rainfall conditions. The output from Model One suggests that the scour-induced total suspended solids in gully pot discharge can be kept well below 25 mg/L if the gully pot fullness level is maintained at under 60%. Results identify the opportunity to incorporate the actual/targeted ecological status of recipients in scheduling gully pot maintenance operations and that proactive gully pots maintenance will reduce the impacts of increased rainfall intensity/duration on the magnitude of sediment scour. Results from Model Two suggest that fine sediments are particularly susceptible to in-pot scour. For example, sediment with a specific gravity of 1.1 and diameter of >63 μm accounts for 50% of scour-induced total suspended solids in gully pot discharge. The effluent suspended solids concentrations predicted by the two models differ by up to two orders of magnitude. However, without further empirical field data pertaining to their respective competences/applications, neither model could be discounted at this stage. For example, the use of Model One is more appropriate in the establishment of gully pot maintenance schedules, with Model Two more suited to the dimensioning of gully pots based on performance requirements. This application, however, relies on the development and adoption of a more stringent regulation on gully pots discharge

Factors influencing the infiltration of pharmaceuticals through soils

Pharmaceuticals and personal care products (PPCPs) are emerging environmental contaminants but studies of their environmental fate have focused on their behaviour during wastewater treatment processes. Little is known about the behaviour of PPCPs in soils and this is important to provide an understanding of how these compounds will be distributed during the infiltration processes which occur both naturally and under a number of treatment procedures. In this study four PPCP compounds (bezafibrate, carbamazepine, chloramphenicol and diclofenac) have been selected for investigation to determine their mobility and leaching behaviour in two types of soils. Under experimental conditions, chloramphenicol showed the highest potential to leach through the soils followed by carbamazepine, bezafibrate and diclofenac, which mirrors the order of their increasing organic carbon adsorption coefficients (Koc). The results suggest that ionic strength, pH and soil organic matter (SOM) are notable factors affecting the sorption and therefore the overall fate of pharmaceutical compounds in the soil environment

Metal size distribution in rainfall and snowmelt-induced runoff from three urban catchments

The size distribution of metals transported by urban runoff has implications for treatment type and design, predicting their mobility and evaluating their potential impact on receiving waters. There is an urgent need to better understand the distribution of metals between fractions, particularly those in the sub-dissolved fractions. As a contribution to addressing this need, this study characterises the size distribution of Cd, Cr, Cu, Ni, V and Zn using conventional and novel techniques. Data is presented as event mean concentrations (EMC) of a total of 18 rainfall and snowmelt events at three urban sites. For all studied metals in all events and at all sites, the contribution of the truly dissolved fraction made a greater contribution to the total concentrations than the colloidal fraction. Truly dissolved Cd and Zn concentrations contributed (on average) 26% and 28% respectively, of the total EMCs with truly dissolved Cu and Ni contributing (on average) 18%. In contrast, only 1% (V) and 3% (Cr) were identified in the truly dissolved fraction. The greatest contribution of truly dissolved Cd, Cu and Zn concentrations (relative to total oncentrations) were reported during rainfall events. However, no seasonal differences were identified and differences between the sites regarding the EMCs distribution by fractions were not at a statistically significant level (p N 0.05) for any metal or event. The loads of truly dissolved and colloidal metals did not follow the patterns of particulate metal loads indicating particulates are not the main source of subdissolved metals. The data suggests that ultrafiltration as a treatment technique would not efficiently mitigate the risks posed by metals to receiving water cologie

The fate of bezafibrate, carbamazepine, ciprofloxacin and clarithromycin in the wastewater treatment process

The progress of four pharmaceuticals (bezafibrate, carbamazepine, clarithromycin and ciprofloxacin) is followed through the treatment stages (screened sewage, settled sewage and final effluent) of a large urban wastewater treatment plant (WWTP) employing activated sludge treatment. Concentrations at the inlet to the WWTP are generally higher than those predicted from consideration of local pharmaceutical consumption and typical excretion data. Percentage removal efficiencies are variable (22.5 – 94.3%) with carbamazepine being the most resistant to elimination

Water and health. [Chapter 6 of 'Sustainable water: chemical science priorities summary report']

Water transports contaminants, including inorganic, organic and biological materials, from various sources both natural and man-made. Such contaminants can enter the human body via water by ingestion, inhalation of water droplets and contact, particularly with broken skin. Water borne diseases have historically had the greatest impact upon human health and continue to contribute to millions of deaths globally per year. Water use and sanitation in the form of hygiene practices act as an important barrier to disease transmission. Disease incidences in countries without basic water and sanitation services are estimated to be eleven times higher for than those in areas with clean water, hygiene practices, and the safe disposal of human wastes. Naturally occurring arsenic compounds (in particular toxic organic species) contaminate substantial groundwater sources. The most seriously affected areas in Sustainable Water: Chemical Science Priorities Royal Society of Chemistry report the world are in India and Bangladesh. Here, 60–100 million people are currently at risk of poisoning as a result of drinking contaminated groundwater where the arsenic arises from the natural bedrock geology. There is a need for portable field-testing kits that are quick, accurate, cheap and reliable that can support remediation efforts. Additionally there is a need for arsenic mitigation technologies that are effective and appropriate for use by local populations. There is also a growing problem with uranium contamination of groundwater, particularly in Eastern Europe. Society is reliant upon man-made chemicals, particularly for food and health, and inevitably such chemicals end up in water systems. Typically these chemical contaminants are either neurotoxins, pharmaceutically active or endocrine disruptors. Additionally there is growing concern over multiple chemical sensitivity1, although scientific evidence is insufficient to prove or disprove this theory at this time. There are two specific problems with man-made chemicals in wastewater: firstly, treatment plants are not designed to remove these chemical products; secondly, chemicals entrained in sediments can be mobilised by chemical and biological processes. Traditionally, pollution by man-made chemicals is reduced by either dilution or through end of pipe remediation technologies. This can be minimised by adopting good practice and integrated pollution prevention and control. This would include measures such as minimising the quantity of materials used and recovering unused materials. Additionally, industrial waste streams should be concentrated as far as possible and mixtures of materials should be avoided, as this will require additional treatment steps and effort

Presence and fate of priority substances in domestic greywater treatment and reuse systems

A wide range of household sources may potentially contribute to contaminant loads in domestic greywater. The ability of greywater treatment systems to act as emission control barriers for household micropollutants, thereby providing environmental benefits in addition to potable water savings, have not been fully explored. This paper investigates the sources, presence and potential fate of a selection of xenobiotic micropollutants in on-site greywater treatment systems. All of the investigated compounds are listed under the European Water Framework Directive as either "Priority Substances" (PS) or "Priority Hazardous Substances" (PHS). Significant knowledge gaps are identified. A wide range of potential treatment trains are available for greywater treatment and reuse but treatment efficiency data for priority substances and other micropollutants is very limited. Geochemical modelling indicates that PS/PHS removal during treatment is likely to be predominantly due to sludge/solid phase adsorption, with only minor contributions to the water phase. Many PS/PHS are resistant to biodegradation and as the majority of automated greywater treatment plants periodically discharge sludge to the municipal sewerage system, greywater treatment is unlikely to act as a comprehensive PS/PHS emission barrier. Hence, it is important to ensure that other source control options (e.g. eco-labeling, substance substitution, and regulatory controls) for household items continue to be pursued, in order that PS/PHS emissions from these sources are effectively reduced and/or phased out as required under the demands of the European Water Framework Directive

Emission control strategies for short-chain chloroparaffins in two semi-hypothetical case cities

The short-chain chloroparaffins (SCCP), (C10-13 chloroalkanes) are identified in the European Water Framework Directive, as priority hazardous substances. Within the ScorePP project, the aim is to develop emission control strategies that can be employed to reduce emissions from urban areas into receiving waters. Six different scenarios for mitigating SCCP emissions in two different semi-hypothetical case cities representing eastern inland and northern coastal conditions have been evaluated. The analysis, associated with scenario uncertainty, indicates that the EU legislation, Best Available Technologies (BAT) and stormwater/CSO management were the most favorable in reducing emissions into the environment

Factors involved in buying Missouri cream

Publication authorized March 4, 1930