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Kerry Fleet BSc (Hons) Environmental Protection, Bournemouth University, 2002
The
Use of Constructed Wetlands to Improve the Water |
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Abstract The Bourne Stream, which takes its route through Poole and Bournemouth, finally joins the sea from an outfall pipe at Bournemouth beach. These are bathing waters under strict compliance with the Bathing Water Directive 76/160/EEC. Historically, the stream has had high levels of bacterial contamination, which has caused problems with regards to lack of compliance with the Directive. Constructed wetlands were built in 2000 using Common Reed Phragmites australis and Cattail Typha latifolia as part of a water quality improvement measure. These emergent macrophytes are well known for their ability to clean waters, which contain organic pollutants and heavy metals. A study was conducted over a 6-month period to assess how effective the wetland system was in improving the water quality of the Bourne Stream. Variables tested for were pH, temperature, BOD, dissolved oxygen, conductivity, nitrates, phosphates, turbidity, E. Coli, Total Coliforms and various heavy metals. Significant improvements were not found. However, some reductions were made in the levels of turbidity, nitrates, phosphates and E.coli. The plants performance was not as well as expected. This was mainly due to the timing of the sampling schedule, which continued into the winter months when plant productivity was becoming lower and dieback becoming prevalent. There is also the possibility of non-point sources of pollution which could be affecting the efficiency of the system.
Contact the author: kerryfleet@hotmail.com |
