New Zealand Journal of Marine and Freshwater Research abstracts
Use of classification and regression tree (CART) analysis with chemical faecal indicators to determine sources of contamination
Jan Gregor
Nick Garrett
Brent Gilpin
Cliff Randall
Darren Saunders
Institute of Environmental Science and Research Limited
P.O. Box 29 181
Christchurch, New Zealand
email: brent.gilpin@esr.cri.nz
Abstract Both human and non-human faecal contamination of environmental waters pose a risk to human health that can be reduced if the source can be identified and responsibility for mitigation accepted. Traditional microbiological indicators are rarely adequate for source identification but some chemical indicators offer promise. In this work, the similarities and differences of selected chemical profiles of different faecal effluent types have been modelled using classification and regression tree (CART) analysis. Human effluents can be distinguished from non-human effluents by the presence of fluorescent whitening agents, and the concentrations or ratios of concentrations of the faecal stanols coprostanol and 24-ethylcoprostanol can distinguish most of the non-human effluent types considered. To allow for the effect of variable dilution when effluents enter environmental waters, ratios of concentrations will be required to establish a model, and a model more complex than CART will be required to apportion multiple effluent-type contamination.
Keywords chemical indicators; faecal effluent; classification and regression tree analysis; faecal stanols; fluorescent whitening agents
M01073 Received 8 August 2001; accepted 1 October 2001
New Zealand Journal of Marine and Freshwater Research, 2002, Vol. 36: 387–398
0028–8330/02/3602–0387 $7.00 © The Royal Society of New Zealand 2002
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