Deriving Nickel (Ni(II)) and Chromium (Cr(III)) Based Environmentally Safe Olivine Guidelines for Coastal Enhanced Silicate Weathering

Enhanced silicate weathering (ESW) by spreading finely ground rock along the coastal zone to remove atmospheric carbon dioxide (CO2) is a proposed climate change mitigation technique. The abundant and fast-dissolving mineral olivine has received most attention for this application. However, contains nickel (Ni) chromium (Cr), which may pose risk marine biota during gigaton-scale ESW Herein we derive first guideline dispersal based on existing environmental quality standards (EQS) Ni Cr. Results show that benthic are at highest when its associated trace metals mixed in surface sediment. Specifically, depending local sedimentary concentrations, 0.059–1.4 kg of m–2 seabed could be supplied without posing risks biota. Accordingly, globally safely sequester only 0.51–37 Gt CO2 21st century. On basis current EQS, conclude adverse impacts from Cr release reduce applicability ESW. Our findings call more in-depth studies potential toxicity toward biota, especially regard bioavailability metal mixture toxicity.