Investigating Climate's Influence on Atrazine Groundwater Contamination

In a world wrestling with food security, using agrichemicals to increase agricultural yield is common, but there can be unintended harmful impacts to human and environmental health. For example, in Nebraska, producers commonly apply the herbicide atrazine - a known endocrine disruptor linked to some cancers and birth defects. Widespread and repeated use of atrazine can cause leaching into groundwater used for drinking water.

To mitigate this problem in Nebraska and across the U.S. in the future, it will be important to predict atrazine persistence, leaching and accumulation beneath agricultural production areas. Shedding light on the contributors to and processes involved with groundwater contamination can help stakeholders better understand herbicide impacts and make informed decisions in regions that rely on herbicides for crop production.

Another major factor affecting water quality is climate change. Storms, strong winds, flooding and drought can impact chemical levels in groundwater. It's these climate scenarios that have engaged University of Nebraska-Lincoln (UNL) civil engineering Ph.D. candidate Chuyang Liu, a DWFI supported student, and his advisor, DWFI Faculty Fellow and UNL associate professor Yusong Li.

The study, completed last year, is part of a broader project that began in 2014 to determine how climate change may impact agro-chemical contamination in groundwater in farmland throughout the Great Plains. The project also evaluates climate and land use influences on trace organic loading rates to groundwater.

In this landmark study-one of the first quantitative studies evaluating how climate change may influence groundwater quality as opposed to quantity-the team modeled 20 different climate scenarios for the years 2056 to 2059. They analyzed the influence of climate uncertainties on predicting the leaching and accumulation of atrazine in a center-pivot irrigation corn production site in Nebraska's Management Systems Evaluation Area.

Results indicate that as normal climate patterns change, atrazine and the contaminants formed from its dissolution may move deeper into subsurface soils, which potentially could increase atrazine concentrations in run-off and groundwater. The research also indicates that atrazine application schedules and irrigation management strategies influence its accumulation and transport. Potential mitigations include changing application timing, quantity and methods, as well as improving irrigation timing and quantity to avoid run-off. Farmers and land managers can use this research data to develop adaptive crop management plans to maintain resilient farmland and support clean water-crucial for Nebraskans living near cropland.