Atrazine Transport Within a Coastal Zone in Southeastern Puerto Rico: a Sensitivity Analysis of an Agricultural Field Model and Riparian Zone Management Model

• Published in: Environmental modeling & assessment Vol. 21; no. 6; pp. 751 - 761
• Main Authors: Williams, Candiss O., Lowrance, Richard, Potter, Thomas, Bosch, David D., Strickland, Timothy
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2016; Springer; Springer Nature B.V
• Subjects: Agricultural land; Agricultural policy; Agriculture; Agrochemicals; Analysis; Applications of Mathematics; Atrazine; Chemical contaminants; Coastal waters; Coastal zone; Conservation; Cyclones; Earth and Environmental Science; Ecosystem management; Ecosystems; Environment; Environmental monitoring; Environmental protection; Estuaries; Farms; Herbicides; Laboratories; Math. Appl. in Environmental Science; Mathematical Modeling and Industrial Mathematics; Operations Research/Decision Theory; Pesticides; Riparian buffers; Riparian forests; Runoff; Sensitivity analysis; Simulation; Soils; Sorghum; Storms; Studies; Surface runoff; Water quality; Water quality measurements; Watershed management; Watersheds; Wetlands; United States > US; Puerto Rico; Predictive models; Hydrology; Conservation Effects Assessment Project; Tropical estuary; Water quality; Wetlands
• ISSN: 1420-2026; 1573-2967
• DOI: 10.1007/s10666-016-9508-4

Agrichemical runoff from farmland may adversely impact coastal water quality. Two models, the Agricultural Policy/Environmental eXtender (APEX) and the Riparian Ecosystem Management Model (REMM), were used to evaluate the movement of the herbicide atrazine to the Jobos Bay National Estuarine Research Reserve from adjacent fields. The reserve is located on Puerto Rico’s southeast coast. Edge-of-field atrazine outputs simulated with the APEX were routed through a grass-forest buffer using the REMM. Atrazine DT 50 (half-life) values measured in both field and buffer soils indicated that accelerated degradation conditions had developed in the field soil due to repeated atrazine application. APEX simulations examined both the measured field and buffer soil atrazine DT 50 and the model’s default value. The use of the measured field soil atrazine degradation rate in the APEX resulted in 33 % lower atrazine transport from the field. REMM simulations indicated that the buffer system had the potential to reduce dissolved atrazine transport in surface runoff by 77 % during non-tropical storm events by increasing infiltration, slowing transport, and increasing time for pesticide degradation. During a large runoff event due to a tropical storm that occurred close to the time of an atrazine application, the REMM simulated only a 37 % reduction in atrazine transport. The results indicate that large storm events soon after herbicide application likely dominate herbicide transport to coastal waters in the region. These results agree with water quality measurements in the reserve. This study demonstrated the sensitivity of these models to variations in DT 50 values in evaluating atrazine fate and transport in the region and emphasizes that the use of measured DT 50 values can improve model accuracy.