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Investigating organic micropollutants in a peri-urban flood plain aquifer

Manamsa, Katya; Lapworth, Dan; Stuart, Marianne. 2011 Investigating organic micropollutants in a peri-urban flood plain aquifer. [Poster] In: Priority substances monitoring & occurrence in the environment: Future challenges for PBTs in surface & groundwaters, Dublin, Ireland, 20 Sept 2011. (Unpublished)

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Abstract/Summary

This poster describes a pilot study to develop the sampling methodology required to investigate the occurrence and distribution of “emerging organic contaminants” in groundwater in an area of anticipated contamination. The study site was the BGS Oxford Observatory on the Port Meadow, within a peri-urban setting, including an area of ancient grassland on the gravels of the flood plain of the River Thames to the northwest of Oxford. Groundwater levels suggest that the regional groundwater flow in the superficial deposits is from northeast to southwest under the main Thames. The site is periodically inundated and groundwater is predominantly reducing. The meadow is flanked on its eastern edge by a closed landfill which accepted all categories of waste from 1937 up to 1980. The leachate plume can be identified across the site by high conductivity, Cl, HCO3, SO4 and DOC. Part of the landfill is now used as allotments. A series of shallow piezometers were sampled in July 2011 for organic micropollutants from the plume, upgradient in the meadow and towards the urban area, across the river and from the river. Samples were collected using a small peristaltic pump equipped with new PTFE tubing. Great care was taken to flush the pumping system with sample and to avoid contamination of the pump or collection bottles. Samples were analysed by the Environment Agency NLS using the semi-quantitative GCMS screening method developed for their organic micropollutant monitoring programme. The results showed that organic micropollutants were present at all sites and included both priority pollutants and emerging contaminants. A total of 26 compounds were detected with N-butyl benzene sulphonamide (BBSA) being both the most frequently detected compound and with the highest maximum concentration. Four priority pollutants were detected, trichloroethene, octyl phenol, anthracene and fluoranthene, and one pesticide, metaldehyde. Some discrimination was evident with the Thames and urban areas showing a different fingerprint from the landfill plume: • Urban sites upgradient of the landfill: phthalate and BBSA plasticisers, poly-aromatic hydrocarbons (PAH), triphenyl phosphate, anti-epileptic drugs • Portmeadow site upgradient from the landfill: BBSA only • Sites in the plume: trichloroethene, 1,4-dioxane, barbiturates, phthalate and BBSA plasticisers, metaldehyde, crotamitron • Site across the river: 1,4-dioxane, phthalate and BBSA plasticisers, metaldehyde • River Thames: phthalate and BBSA plasticisers, caffeine, anti-epileptic drugs, PAH The next phase of the project will investigate changes in the occurrence of organic micropollutants during the autumn and winter when groundwater levels are higher and there is floodplain inundation.

Item Type: Publication - Conference Item (Poster)
Programmes: BGS Programmes 2010 > Groundwater Science
Additional Keywords: GroundwaterBGS, Groundwater, Groundwater quality
NORA Subject Terms: Earth Sciences
Hydrology
Related URLs:
Date made live: 21 Sep 2011 13:18
URI: http://nora.nerc.ac.uk/id/eprint/15146

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