Potential environmental impact of bromoform from Asparagopsis farming in Australia

[摘要] To mitigate the rumen enteric methane (CH 4 ) produced by ruminantlivestock, Asparagopsis taxiformis is proposed as an additive to ruminant feed. During thecultivation of Asparagopsis taxiformis in the sea or in terrestrially based systems, this macroalgae,like most seaweeds and phytoplankton, produces a large amount of bromoform(CHBr 3 ) , which contributes to ozone depletion once released into theatmosphere. In this study, we focus on the impact of CHBr 3 on thestratospheric ozone layer resulting from potential emissions from proposed Asparagopsis cultivation in Australia. The impact is assessed by weighting the emissionsof CHBr 3 with its ozone depletion potential (ODP), which istraditionally defined for long-lived halocarbons but has also been appliedto very short-lived substances (VSLSs). An annual yield of ∼3.5   ×  10 4  Mg dry weight is required to meet the needs of 50 %of the beef feedlot and dairy cattle in Australia. Our study shows that theintensity and impact of CHBr 3 emissions vary, depending on locationand cultivation scenarios. Of the proposed locations, tropical farms nearthe Darwin region are associated with the largest CHBr 3  ODP values.However, farming of Asparagopsis using either ocean or terrestrialcultivation systems at any of the proposed locations does not have the potentialto significantly impact the ozone layer. Even if all Asparagopsis farming were performedin Darwin, the CHBr 3 emitted into the atmosphere would amount to lessthan 0.02 % of the global ODP-weighted emissions. The impact of remainingfarming scenarios is also relatively small even if the intended annual yieldin Darwin is scaled by a factor of 30 to meet the global requirements, whichwill increase the global ODP-weighted emissions up to ∼0.5  %.

[学科分类] 医学（综合）