In the last decade, flooding has caused the death of over 60,000 people and affected over 900 million people globally. This is expected to increase as a result of climate change, increased populations and urbanisation. Floods can cause infections due to the release of water-borne pathogenic microorganisms from surcharged combined sewers and other sources of fecal contamination. This research contributes to a better understanding of how the occurrence of water-borne pathogens in contaminated shallow water bodies is affected by different environmental conditions. The inactivation of fecal indicator bacteria Escherichia coli was studied in an open stirred reactor, under controlled exposure to simulated sunlight, mimicking the effect of different latitudes and seasons, and different concentrations of total suspended solids (TSS) corresponding to different levels of dilution and runoff. While attachment of bacteria on the solid particles did not take place, the decay rate coefficient, k (d−1), was found to depend on light intensity, I (W m−2), and duration of exposure to sunlight, T (h d−1), in a linear way (k = kD+ 0.03·I and k = kD+ 0.65·T, respectively) and on the concentration of TSS (mg L−1), in an inversely proportional exponential way (k = kD+ 14.57·e−0.02·[TSS]). The first-order inactivation rate coefficient in dark conditions, kD= 0.37 d−1, represents the effect of stresses other than light. This study suggests that given the sunlight conditions during an urban flood, and the concentration of indicator organisms and TSS, the above equations can give an estimate of the fate of selected pathogens, allowing rapid implementation of appropriate measures to mitigate public health risks.Article HighlightsIt was demonstrated under controlled conditions that the inactivation of fecal indicator bacteria E. coli is higher under higher solar irradiance, longer duration of daylight and low TSS concentrations.The results indicate that under high TSS concentrations the bacteria, even if not attached on particles, are protected from photo-inactivation for a period of a few days, as the decay rate decreases exponentially with an increase in TSS concentration.

中文翻译：

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人工太阳辐射对城市洪水病原指示生物灭活的影响

在过去十年中，洪水已导致 60,000 多人死亡，并影响了全球 9 亿多人。由于气候变化、人口增加和城市化，预计这一数字还会增加。由于来自超载合流下水道和其他粪便污染源的水传播病原微生物释放，洪水可引起感染。这项研究有助于更好地了解受污染浅水体中水传播病原体的发生如何受到不同环境条件的影响。在开放式搅拌反应器中研究粪便指示菌大肠杆菌的灭活，在受控暴露于模拟阳光下，模拟不同纬度和季节的影响，和不同浓度的总悬浮固体 (TSS) 对应于不同的稀释和径流水平。虽然没有发生细菌附着在固体颗粒上，但发现衰减率系数 k (d−1) 取决于光强度 I (W m−2) 和暴露在阳光下的持续时间 T ( hd-1)，以线性方式（k = kD+ 0.03·I 和 k = kD+ 0.65·T，分别）和 TSS 浓度（mg L-1），以成反比指数方式（k = kD+ 14.57 ·e-0.02·[TSS])。黑暗条件下的一阶失活率系数 kD= 0.37 d-1，代表了光以外的应力的影响。这项研究表明，考虑到城市洪水期间的阳光条件以及指示生物和 TSS 的浓度，上述方程可以估计选定病原体的命运，