Remote sensing of volatile organic compounds release during prescribed fires in pine forests using open-path Fourier transform infra-red spectroscopy

Background

Extreme wildfires have increased in recent decades, yet the consequences of extreme fire behaviour are not fully comprehended. The study of prescribed burning provides opportunities to advance understanding of some overlooked processes in fire behaviour, such as the role of the release of volatile organic compounds (VOC).

Aims

The aim of this study was to assess VOC (α-pinene, β-pinene, and limonene), NH₃, CO and CO₂ emissions during prescribed fires in pine barrens vegetation at the Albany Pine Bush Preserve, USA.

Methods

Measurements performed by open-path Fourier transform infra-red spectroscopy (OP-FTIR) quantified VOC concentrations and characterised emissions during four independent prescribed burns.

Key results

Combustion products (e.g. CO₂, CO, CH₄) and VOC exhibited similar emission behaviour during thermal degradation, though VOC concentrations appeared to be independent of the type of biomass burned, unlike those of combustion products; Pinus strobus L. emitted two orders of magnitude higher than Pinus rigida Mill.; VOC and CO are statistically correlated (R² = 0.84).

Conclusions

These results confirmed that OP-FTIR is a feasible approach for gathering qualitative and quantitative information regarding VOC emission during prescribed fires.

Implications

Quantification of VOC concentrations during prescribed fires helps characterise its relationships with greenhouse gas emissions (e.g. CO₂ and CO) at different burning conditions (e.g. wind, biomass type), which could be incorporated into existing fire behaviour models to enhance their ability to better predict fire propagation.