Institute of Environmental Science and Research Limited, Christchurch Science Centre, PO Box 29-181, Christchurch, New Zealand; Waterways Centre for Freshwater Management, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
Institute of Environmental Science and Research Limited, Christchurch Science Centre, PO Box 29-181, Christchurch, New Zealand.
Sci Total Environ. 2014 Jul 1;485-486:666-680. doi: 10.1016/j.scitotenv.2014.03.027. Epub 2014 Apr 22.
A series of large earthquakes struck the city of Christchurch, New Zealand in 2010-2011. Major damage sustained by the sewerage infrastructure required direct discharge of up to 38,000 m(3)/day of raw sewage into the Avon River of Christchurch for approximately six months. This allowed evaluation of the relationship between concentrations of indicator microorganisms (Escherichia coli, Clostridium perfringens and F-RNA phage) and pathogens (Campylobacter, Giardia and Cryptosporidium) in recreational water and sediment both during and post-cessation of sewage discharges. Giardia was the pathogen found most frequently in river water and sediment, although Campylobacter was found at higher levels in water samples. E. coli levels in water above 550 CFU/100 mL were associated with increased likelihood of detection of Campylobacter, Giardia and Cryptosporidium, supporting the use of E. coli as a reliable indicator for public health risk. The strength of the correlation of microbial indicators with pathogen detection in water decreased in the following order: E. coli>F-RNA phage>C. perfringens. All the microorganisms assayed in this study could be recovered from sediments. C. perfringens was observed to accumulate in sediments, which may have confounded its usefulness as an indicator of fresh sewage discharge. F-RNA phage, however, did not appear to accumulate in sediment and in conjunction with E. coli, may have potential as an indicator of recent human sewage discharge in freshwater. There is evidence to support the low-level persistence of Cryptosporidium and Giardia, but not Campylobacter, in river sediments after cessation of sewage discharges. In the event of disturbances of the sediment, it is highly probable that there could be re-mobilisation of microorganisms beyond the sediment-water exchange processes occurring under base flow conditions. Re-suspension events do, therefore, increase the potential risk to human health for those who participate in recreational and work-related activities in the river environment.
2010-2011 年，新西兰克赖斯特彻奇市发生了一系列大地震。下水道基础设施遭受重大破坏，需要将多达 38000 立方米/天的未经处理的污水直接排入克赖斯特彻奇的雅芳河，持续了大约六个月。这使得我们能够评估指示微生物（大肠杆菌、产气荚膜梭菌和 F-RNA 噬菌体）和病原体（弯曲杆菌、贾第虫和隐孢子虫）在污水排放期间和停止排放后在娱乐用水和沉积物中的浓度之间的关系。贾第虫是在河水中和沉积物中最常发现的病原体，尽管在水样中发现了更高水平的弯曲杆菌。水中大肠杆菌水平超过 550 CFU/100 mL 与弯曲杆菌、贾第虫和隐孢子虫检测率增加有关，支持将大肠杆菌用作公共卫生风险的可靠指标。在水中微生物指标与病原体检测的相关性强度按以下顺序降低：大肠杆菌>F-RNA 噬菌体>产气荚膜梭菌。本研究中检测到的所有微生物都可以从沉积物中回收。观察到产气荚膜梭菌在沉积物中积累，这可能使其作为新鲜污水排放的指示物的用处受到干扰。然而，F-RNA 噬菌体似乎不会在沉积物中积累，并且与大肠杆菌一起，可能具有作为淡水近期人类污水排放的指示物的潜力。有证据表明，在污水排放停止后，隐孢子虫和贾第虫在河底沉积物中的低水平持久性，但弯曲杆菌则不然。在沉积物受到干扰的情况下，在基流条件下发生的沉积物-水交换过程之外，微生物很有可能重新迁移。因此，悬浮事件增加了那些在河流环境中从事娱乐和与工作相关活动的人对人类健康的潜在风险。
