Affiliation:
1. National Institute of Water and Atmospheric Research (NIWA), P.O. Box 11-115, Hamilton, New Zealand r.davies-colley@niwa.co.nz
2. University of Waikato Biology Department, Hamilton, New Zealand elydiard@gmail.com
Abstract
Rainstorms can flush large amounts of faecal pollution from land sources into water bodies, threatening, particularly, contact recreation and bivalve shellfish harvest. We quantified the faecal pollution loads of stormflows in the Toenepi Stream, draining a catchment in intensive dairy-farming (Waikato Region, New Zealand). In this stream, as is typical, E. coli concentration peaks well ahead of flow on storm flow hydrographs, which complicates calculation of loads. However, stormflow E. coli concentration correlates with turbidity in the Toenepi Stream, so we used a continuously-recording turbidimeter to estimate ‘continuous’ E. coli concentrations and thence E. coli fluxes (cfu/s) and loads (cfu). E. coli was measured on 25 out of the 30 (83%) of storm events occurring in the Toenepi Stream in a 12-month period, using an automatic sampler sampling every 2 hrs over stormflow hydrographs for microbial analysis (within 48 hr). E. coli (cfu) yield on individual events tended to increase systematically with event size. The sum of storm-flow exports (occurring 24% of total time) amounted to 95% of the total annual E. coli export from the Toenepi Catchment. The stream exported about 6% of the (expected) total E. coli production in cattle faeces within the catchment.
Subject
Water Science and Technology,Environmental Engineering
Cited by
53 articles.
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