Reactive films for mitigating methyl bromide emissions from fumigated soil

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Agricultural Technology

Background:

• Methyl bromide (MeBr) emissions from agricultural fumigation contribute to stratospheric ozone depletion.
• Despite phase-out, MeBr use persists under Critical Use Exemptions, necessitating emission control strategies.

Purpose of the Study:

• To design and evaluate novel reactive films (RFs) for limiting MeBr loss from soils.
• To assess the efficacy of RFs containing ammonium thiosulfate (ATS) in transforming MeBr.

Main Methods:

• Reactive films with a dry ATS layer sandwiched between HDPE and VIF/HDPE films were developed.
• MeBr diffusion and transformation were quantified using a stainless-steel permeability cell at various temperatures.
• The performance of activated (water-treated) and dry RFs was compared.

Main Results:

• Dry RFs were ineffective, but water-activated RFs substantially depleted MeBr.
• MeBr half-life in the presence of activated RF was approximately 9.0 hours at 20°C, showing temperature sensitivity.
• With a VIF upper layer, less than 0.15% of MeBr diffused through the film, with most being transformed.

Conclusions:

• Water-activated reactive films containing ATS show significant potential for reducing MeBr emissions from agricultural soils.
• These RFs can effectively transform MeBr, minimizing its atmospheric release and supporting ozone layer protection.
• The findings suggest a viable strategy for managing MeBr emissions under ongoing agricultural use.