RAPID: Assessing the fate of flood-born contaminants

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Floods can cause significant problems for nature and society. In addition to water damage, toxic contaminants can be mobilized and affect public health and safety. However, only little is known about the nature of contaminants and how they are distributed during floods. The proposed project studies potentially dangerous contaminants in water and flood deposits from the 2019 Missouri River flood, Nebraska. Rural and urban areas are studied to assess the impact on the environment and society. The goal is to identify contaminants and understand how they are transported. The results will help to identify areas where they were deposited and may pose health risks. Catastrophic flood events, such as the one studied here, are predicted to become more frequent in the future. Understanding what the most dangerous contaminants are, where they are most likely to be deposited, and for long they remain a threat to nature and society will help to guide future rural and urban development strategies.To determine how contaminants were redistributed during the catastrophic Missouri River flood event, the proposed project will collect soil, river and lake sediment samples near Omaha, Nebraska. The samples will be taken along detailed profiles with sampling intervals 100 m as well as in a larger-scale grid pattern (3 km2, 500 m intervals) and analyzed for metals and total phosphorous, nitrogen and organic carbon contents. Water samples will be taken from rivers and lakes/ponds in the field area and complemented by groundwater samples from existing wells. Soil and sediment samples will be analyzed using ICP-MS (metals), ICP-AES (phosphorous), thermal conductivity detection (nitrogen), and infrared absorption (carbon). Water samples will be analyzed for P and N species via a portable Hach DR 1900 spectrophotometer. The data will allow to identify what contaminants are typically associated with urban and rural agricultural areas, quantify their abundances, and determine how they were redistributed during the flood event. The results will be integrated to develop models that can be used to predict where toxic contaminants are most likely to be deposited during and/or after catastrophic floods. Resampling of the same locations during the following years can then help to understand residence times of contaminants and their long-lasting effects on the environment. Because extreme weather events are predicted to become more frequent in the future, this project will provide an important first step to design urban and rural development strategies aimed at reducing the ecologic, social, and economic damage associated with catastrophic floods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.