Staff Scientist & Carbon Removal & Mineralization Program Lead, Lawrence Berkeley National Laboratory
Talk Title: Carbon Management via Enhanced Rock Weathering
Bhavna Arora is a Staff Scientist and the Carbon Removal and Mineralization Lead in the Energy Geosciences Division at Lawrence Berkeley National Laboratory. Her research uses process-based models for solving diverse issues in the earth and environmental sciences such as water resources management, CO2 sequestration, and sustainable agriculture.
“Carbon Management via Enhanced Rock Weathering“
Enhanced rock weathering (ERW) using silicate amendments is a competitive carbon removal strategy that can potentially remove 0.5-2 gigatons of carbon annually by 2050. However, understanding the achievable rate enhancement in croplands under different abiotic-biotic processes and climatic interactions is a key knowledge gap. To address this, we have developed a comprehensive reaction network incorporating several abiotic and biotic processes impacting weathering rates, such as aqueous complexation, mineral precipitation and dissolution, and microbially mediated redox reactions. Using this complex reaction network for two soil textures (sandy loam, silty loam), we analyzed the impact of precipitation and temperature variations for three sites within agriculturally dominated California, Arkansas and Iowa. Interestingly, a greater potential for ERW using forsterite was predicted under steady precipitation conditions, relative to transient conditions for all three sites. Transient precipitation conditions contributed to transport limitation of gas phase components (air, water vapor and CO2) under high infiltration, while lower infiltration decreased reaction rates. Combined, the transient (high and low infiltration) conditions showed lower overall forsterite dissolution rates compared to steady precipitation/infiltration scenario. To further understand the impact of hydrological transients on CO2 sequestration, we extend our model to rice paddies which typically have high water levels and highly organic environment. Our results suggest that silicate rock amendments can provide the dual benefit of reducing methane emissions while increasing carbon storage in rice fields. Together, these efforts provide critical new information on achievable weathering rates, and constraints on ERW adoption under differing hydrological and temperature conditions.