Increased carbon capture by a silicate-treated forested watershed affected by acid deposition

Abstract

Abstract. Meeting internationally agreed-upon climate targets requires\ncarbon dioxide removal (CDR) strategies coupled with an urgent phase-down of\nfossil fuel emissions. However, the efficacy and wider impacts of CDR are\npoorly understood. Enhanced rock weathering (ERW) is a land-based CDR\nstrategy requiring large-scale field trials. Here we show that a low 3.44\u2009t\u2009ha −1 wollastonite treatment in an 11.8\u2009ha acid-rain-impacted forested watershed in New Hampshire, USA, led to cumulative carbon capture by carbonic acid weathering of 0.025–0.13\u2009t\u2009CO 2 \u2009ha −1 over 15\xa0years. Despite a 0.8–2.4\u2009t\u2009CO 2 \u2009ha −1 logistical carbon penalty from mining,\ngrinding, transportation, and spreading, by 2015 weathering together with\nincreased forest productivity led to net CDR of 8.5–11.5\u2009t\u2009CO 2 \u2009ha −1 . Our results demonstrate that ERW may be an effective, scalable\nCDR strategy for acid-impacted forests but at large scales requires\nsustainable sources of silicate rock dust.