National Institute of Water & Atmospheric Research, PO Box 11-115 Hamilton, New Zealand.
J Water Health. 2011 Mar;9(1):59-69. doi: 10.2166/wh.2010.061.
The faecal indicator bacterium Escherichia coli and thermotolerant Campylobacter spp., which are potentially pathogenic, were investigated in the Toenepi Stream draining a pastoral catchment dominated by dairying. Bacteria concentrations were monitored routinely at fortnightly intervals over 12 months and intensively during storm events to compare the transport dynamics of bacterial indicator and pathogen under varying hydro-meteorological conditions. Routine monitoring indicated median concentrations of 345 E. coli MPN 100 ml(-1) and relatively low concentrations of 2.3 Campylobacter MPN 100 ml(-1). The bacterial flux was three orders of magnitude greater under elevated stream flow compared with base-flow. E. coli peak concentrations occurred very close to the turbidity peak and consistently ahead of the Campylobacter spp. peak (which was close to the hydrograph peak). We postulate that, under flood conditions, the E. coli peak reflects the entrainment and mobilisation of in-stream stores on the flood wave front. In contrast, Campylobacter spp. are derived from wash-in from land stores upstream and have travelled at the mean water velocity which is slower than the speed of the flood wave. Our findings of different dynamics for E. coli and Campylobacter spp. suggest that mitigation to reduce faecal microbial impacts from farms will need to take account of these differences.
在托内皮溪进行了研究，该溪流排泄着以奶牛场为主的牧区流域。该溪水中存在粪大肠菌和耐热型弯曲杆菌（可能具有致病性）等指示菌。在 12 个月期间，每两周监测一次常规细菌浓度，并在暴风雨期间进行密集监测，以比较在不同水文气象条件下，细菌指示菌和病原体的输移动态。常规监测表明，大肠菌群的中位数浓度为 345 个 MPN/100ml，而弯曲杆菌的浓度相对较低，为 2.3 个 MPN/100ml。与基流相比，在升高的水流条件下，细菌通量高三个数量级。大肠菌群浓度峰值与浊度峰值非常接近，且始终先于弯曲杆菌峰值（该峰值接近水文曲线峰值）出现。我们推测，在洪水条件下，大肠菌群浓度峰值反映了洪水波前锋上的溪流存储物的夹带和移动。相比之下，弯曲杆菌是从上游陆地存储物冲刷而来的，其移动速度比洪水波的速度慢，所以滞后于大肠菌群浓度峰值出现。我们发现大肠菌群和弯曲杆菌的动力学存在差异，这表明减轻农场粪便微生物影响的措施需要考虑到这些差异。
