College of the Environment & Ecology, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen 361102, China.
Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Sci Total Environ. 2024 Nov 25;953:175731. doi: 10.1016/j.scitotenv.2024.175731. Epub 2024 Sep 2.
Extreme precipitation can significantly influence the water quality of surface waters. However, the total amount of bacteria carried by rainfall runoff is poorly understood. Here, thirty rainfall scenarios were simulated by artificial rainfall simulators, with designed rainfall intensity ranging from 19.3 to 250 mm/h. The instantaneous concentration ranges of R2A, nutrient agar (NA) culturable bacteria, and viable bacteria in runoff depended on the types of underlying surfaces. The instantaneous bacterial concentrations in runoff generated by forest lands, grasslands and bare soil were: R2A culturable bacteria = 10, 10, 10 colony-forming units (CFU)/mL, NA culturable bacteria = 10, 10, 10 CFU/mL, and viable bacteria = 10, 10, 10 cells/mL. Based on the measured bacterial instantaneous concentration in runoff, cumulative dynamic models were established, and the maximum amount of culturable bacteria and viable bacteria entering water sources were estimated to be 10 CFU/m and 10 cells/m, respectively. The model fitting and the bacterial accumulation dynamics were influenced by the rainfall types (p < 0.01). Surface runoff from the underlying surface of forest lands and grasslands had a high microbial risk that persisted even during the "Drought-to-Deluge Transition". Bacterial accumulation models provide valuable insight for predicting microbial risks in catchments during precipitation and can serve as theoretical support for further ensuring the safety of drinking water under the challenge of climate change.
极端降水会显著影响地表水质。然而，降雨径流水携带的细菌总量仍不清楚。本研究采用人工模拟降雨器模拟了 30 种降雨情景，设计的降雨强度范围为 19.3 至 250 mm/h。不同下垫面类型的径流水中 R2A 可培养菌、营养琼脂（NA）可培养菌和活菌的瞬时浓度范围不同。林地、草地和裸地径流水中的瞬时细菌浓度分别为：R2A 可培养菌=10、10、10 菌落形成单位（CFU）/mL，NA 可培养菌=10、10、10 CFU/mL，活菌=10、10、10 细胞/mL。基于径流水中实测的细菌瞬时浓度，建立了累积动态模型，估计进入水源的可培养细菌和活菌的最大量分别为 10 CFU/m 和 10 细胞/m。模型拟合和细菌积累动态受降雨类型（p<0.01）的影响。森林和草地下垫面的地表径流具有较高的微生物风险，甚至在“旱转洪”期间也持续存在。细菌积累模型为预测降水期间集水区的微生物风险提供了有价值的见解，并可为进一步确保气候变化挑战下饮用水的安全提供理论支持。
