Atrazine mineralization potential in two wetlands

Area of Science:

• Environmental Science
• Microbiology
• Ecotoxicology

Background:

• Atrazine is a widely used herbicide in agriculture.
• Its fate in agricultural soils is well-documented, but less is known about its attenuation in wetlands.
• Wetlands play a crucial role in filtering agricultural runoff.

Purpose of the Study:

• To evaluate the potential for atrazine mineralization in two distinct wetland systems in central Ohio.
• To compare atrazine degradation in a constructed wetland receiving agricultural runoff versus a natural fen.
• To investigate the microbial communities involved in atrazine attenuation.

Main Methods:

• Mineralization potential was measured using 14CO2 evolution from radiolabeled atrazine ([U-ring-14C]-atrazine).
• Samples included wetland sediment, concentrated wetland water, and river water.
• Polymerase Chain Reaction (PCR) and Southern blots were used to detect specific atrazine-degrading genes (atzA and trzD).

Main Results:

• The constructed wetland demonstrated significant atrazine mineralization (70-80% in 1 month).
• Concentrated water and river samples also showed high mineralization rates.
• Mineralization was highest in the top 5 cm of sediment.
• Positive PCR signals for atrazine-degrading genes were detected in the constructed wetland, correlating with mineralization activity.
• Minimal atrazine mineralization and gene detection occurred in the natural fen (Cedar Bog).

Conclusions:

• Sediment microbial communities in the Olentangy constructed wetland effectively mineralize atrazine.
• Atrazine attenuation in wetlands is influenced by direct agricultural runoff and potentially seasonality.
• The presence of specific genes correlated with observed atrazine mineralization activity.