Particulate matter emissions from biochar-amended soils as a potential tradeoff to the negative emission potential

Abstract

Novel carbon sequestration strategies such as large-scale land application of biochar may provide sustainable pathways to increase the terrestrial storage of carbon. Biochar has a long residence time in the soil and hence comprehensive studies are urgently needed to quantify the environmental impacts of large-scale biochar application. In particular, black carbon emissions from soils amended with biochar may counteract the negative emission potential due to the impacts on air quality, climate, and biogeochemical cycles. We investigated, using wind tunnel experiments, the particulate matter emission potential of a sand and two agriculturally important soils amended with different concentrations of biochar, in comparison to control soils. Our results indicate that biochar application considerably increases particulate emissions possibly by two mechanisms–the accelerated emission of fine biochar particles and the generation and emission of fine biochar particles resulting from abrasion of large biochar particles by sand grains. Our study highlights the importance of considering the background soil properties (e.g., texture) and geomorphological processes (e.g., aeolian transport) for biochar-based carbon sequestration programs.

Negative emissions—Part 2: Costs, potentials and side effects

“…Fine biochar particles may also be released into the atmosphere during production, transportation and distribution by wind. These black carbon aerosols can reduce air quality and cause a positive direct and indirect radiative forcing which would further reduces the net mitigation effect of biochar application (Ravi et al 2016, Genesio et al 2016.…”

Dynamic effects of biochar concentration and particle size on hydraulic properties of sand

“…Because of these benefits, biochar is increasingly used for stormwater capture, treatment, and reuse in water‐stressed urban areas (Mohanty et al, ). However, several potential negative impacts of large‐scale application have also been reported (Lian & Xing, ), including particulate emission via air (Ravi et al, ) and remobilization of contaminated biochar particles from amended medium (Mohanty & Boehm, ; Mukherjee & Lal, ).…”

Impact of Biochar Formulation on the Release of Particulate Matter and on Short-Term Agronomic Performance

“…On the other hand, fragmentation involves the release of fine and ultrafine particulate in atmosphere, something that has the potential to fully reverse its mitigation potential [12]. The release of particulate matter from biochar in the atmosphere was demonstrated to also occur after incorporation into soil in a wind-tunnel experiment [14,15,21]. In particular, the finest particles (≤2.5 μm) fall in the category of black carbon aerosol, which is defined as a refractory, water insoluble carbonaceous material strongly absorbing shortwave radiation at wavelength of 550 nm [16].…”