41 research outputs found
A comparison of carbonyl compound concentrations at urban roadside and indoor sites
No full textMeasurements of formaldehyde, acetaldehyde, hexanal, crotonaldehyde, acrolein, propanal, benzaldehyde and iso-valeraldehyde concentrations were made at two locations (four sites) in London, UK. One location was in Ealing, West London, while the other was in Wood Green, North London. At each location, a residential and commercial roadside site was identified and monitored. The measurements were made using a derivatisation technique in which sample air was pumped through an acidified solution of 2,4-dinitrophenylhydrazine, producing hydrazones which were separated and quantified using High Performance Liquid Chromatography (HPLC). Quantitative determinations were made for 26 and 47 samples at the Ealing and Wood Green locations respectively during 1991 and 1992. The average concentrations determined at the Ealing location for formaldehyde, acetaldehyde, hexanal and crotonaldehyde (taking into account concentrations below the detection limits) were 15.0, 2.5, 1.5 and 1.2 ppb, respectively (residential site), and for the commercial site the corresponding values were 19.2, 1.6, 1.2 and 0.5 ppb. Similarly, at the residential site in Wood Green, the average concentrations for formaldehyde, acetaldehyde, hexanal and crotonaldehyde were 3.4, 1.9, 0.5 and 0.5 ppb, respectively, while at the commercial site the average concentrations for formaldehyde, acetaldehyde and hexanal were 7.4, 2.3 and 0.6 ppb. Acrolein, propanal, benzaldehyde and iso-valeraldehyde were not detected at either survey location. At the residential location in Wood Green, sufficient samples were collected to allow the data to be statistically divided into morning and afternoon collection periods, and the data show that the aldehyde concentrations were generally slightly higher in the afternoon. The observed concentrations reported here are compared with previously reported measurements in the UK and with indoor measurements taken at the Bounds Green Campus of Middlesex University. The advantages and limitations of the method employed are also discussed and compared with a solid-phase extraction technique.<br/
Low temperature biodegradation of airport de-icing fluids
No full textThe biodegradabilities of glycol- and acetate-based aircraft de-icing fluids on airport surfaces have been investigated at three temperatures between 0°C and 10°C. The aqueous solubilities of these substances can result in high BOD loadings in runoff and pose serious toxicity problems in receiving waters. The measured surface biodegradation rates for de-icing products based on ethylene/diethylene glycol (Konsin), propylene glycol (Kilfrost) and potassium acetate (Clearway) at 4°C were 0.082, 0.073 and 0.033 day-1. The resulting reductions in the potential BOD loadings, of a single application of a typical mixture of these products, over a 5 day biodegradation period are predicted to be 32.9%, 30.2% and 21.4%, respectively at 8°C, 4°C and 1°C. For consecutive daily applications, the comparable cumulative reductions over 5 days are 20.8%, 18.9% and 13.3%. The subsequent savings in the amount of treatment required for airport runoff prior to safe discharge to receiving waters are discussed and hence the relevance of surface biodegradation processes to the design of stormwater treatment systems involving the wash-off of biodegradable pollutants following retention on urban surfaces.</jats:p
Sewer losses and interactions with groundwater quality
No full textInflow/infiltration (I/I) and infiltration/exfiltration (I/E) are interactive processes which dynamically affect sewer and groundwater performance. The incidence and condition of “critical” sewers in the UK are identified together with chemical and bacterial methods of quantifying I/E and its potential impact on sewer performance and on urban groundwater pollution. Whilst the impacts of I/E do not appear to be substantial on the basis of existing evidence, some caution is advocated in respect of long term sewer sustainability.</jats:p
Managing a Shared Collection in a Changing World
No full textThe author of this commentary describes the Maine Shared Collections Cooperative and its efforts to address members\u27 concerns about their commitments as library needs and functions change
A systematic approach for the comparative assessment of stormwater pollutant removal potentials
No full textThis paper describes the development of a methodology to theoretically assess the stormwater pollutant removal performances of structural best management practices (BMPs). The method combines the categorisation of the relative importance of the primary removal processes within 15 different BMPs with an evaluation of the ability of each process to remove a pollutant in order to generate a value representing the pollutant removal potential for each BMP. The methodology is demonstrated by applying it separately to a set of general water quality indicators (total suspended solids, biochemical and chemical oxygen demand, nitrates, phosphates and faecal coliforms) to produce a ranked list of BMP pollutant removal efficiencies. Given the limited amount of available monitoring data relating to the differential pollutant removal capabilities of BMPs, the resulting prioritisation will support stakeholders in making urban drainage decisions from the perspective of pollutant removal. It can also provide inputs to existing urban hydrology models, which aim to predict the treatment performances of BMPs. The level of resilience of the proposed approach is tested using a sensitivity analysis and the limitations in terms of BMP design and application are discussed
Comportement de certains polluants émergents dans les techniques alternatives (BMPs) de gestion des eaux pluviales
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