Triazine and other herbicides in sediments of lower Laurentian Great Lakes - pre- and post-depositional mobility and in-situ degradation.

Herbicide accumulation and mobility in sediments of Lakes Erie and Ontario reveal significant pre- and post-depositional processes, with atrazine fluxes showing longitudinal trends over decades.

• Why it matters: Understanding herbicide fate in Great Lakes sediments is crucial for assessing long-term environmental impacts and contamination history, which are poorly documented despite extensive herbicide use in North America's corn belt.
• What they did: The study analyzed 12 sediment cores and over 70 surface samples from Lakes Erie and Ontario for atrazine, simazine, alachlor, and DEA, developing predictive models across five lakes using multivariate regressions.
• The result: Findings indicate that herbicide profiles are affected by both water-driven mobility and downward leaching, complicating historical contamination assessments and highlighting ongoing in-situ degradation processes.