Significant loss of soil inorganic carbon at the continental scale

Abstract

Widespread soil acidification due to atmospheric acid deposition and agricultural fertilization may greatly accelerate soil carbonate dissolution and CO2 release. However, to date, few studies have addressed these processes. Here, we use meta-analysis and nationwide-survey datasets to investigate changes in the soil inorganic carbon (SIC) stocks in China. We observe an overall decrease in the SIC stocks in topsoil (0-30 cm) (11.33 g C m–2 yr–1) during the 1980 s and 2010 s. The total SIC stocks have decreased by approximately 8.99 ± 2.24% (1.37 ± 0.37 Pg C). The average SIC losses across China (0.046 Pg C yr–1) and in cropland (0.016 Pg C yr–1) account for approximately 17.6–24.0% of the terrestrial C sink and 57.1% of the soil organic carbon sink in cropland, respectively. Nitrogen deposition and climate change have profound influences on SIC cycling. We estimate that approximately 19.12–19.47% of the SIC stocks will be further lost by 2100. The consumption of SIC may offset a large portion of the global efforts aimed at ecosystem carbon sequestration, which emphasizes the importance of better understanding the indirect coupling mechanisms of nitrogen and carbon cycling and of effective countermeasures to minimize SIC loss.

Qinghai‐Tibet Plateau Permafrost at Risk in the Late 21st Century

“…Permafrost on the QTP has been observed to have degraded substantially as a result of drastic climate warming (Biskaborn et al., 2019; G. Cheng & Wu, 2007; G. Cheng et al., 2019), as evidenced by increasing ground temperature (Q. Wu & Zhang, 2008), thickening of the active layer (Luo et al., 2016), and continued decline in cold permafrost area (Ran et al., 2018). These changes pose significant impacts on ecology, hydrology, biogeochemistry, and engineering infrastructure on the third pole and surrounding areas (Song et al., 2022; W. Wang et al., 2018; Xiang et al., 2016; Yang et al., 2018). Particularly, permafrost thawing can trigger the release of soil organic carbon (SOC) into the atmosphere, which in turn affects climate warming (Burke et al., 2012; F. Cheng et al., 2022; DeConto et al., 2012; MacDougall et al., 2012; Mu et al., 2020; T. Wang et al., 2020).…”

“…cold permafrost area (Ran et al, 2018). These changes pose significant impacts on ecology, hydrology, biogeochemistry, and engineering infrastructure on the third pole and surrounding areas (Song et al, 2022;W. Wang et al, 2018;Xiang et al, 2016;Yang et al, 2018).…”

Technologies and perspectives for achieving carbon neutrality

“…Biochar amendments can also be an effective approach to increase SOC stocks due to the stable (on a millennium timescale) nature of the C contained in the biochar. 187 , 188 Soil acidification due to atmospheric nitrogen deposition in forest and grassland and excessive nitrogen fertilizer application in croplands should also be avoided to reduce the loss of soil inorganic C. 189 , 190 Application of crushed calcium- and magnesium-rich silicate rocks to soils is proposed for large-scale CO 2 removal. 191 This technology was called enhanced rock weathering, which increases soil alkalinity, and thus atmospheric CO 2 can be converted into dissolved inorganic C to be finally transported to the ocean, where the stored C has a long lifespan via land surface runoff.…”

Soil texture and microorganisms dominantly determine the subsoil carbonate content in the permafrost-affected area of the Tibetan Plateau

“…In arid and semi-arid areas, the SIC (mainly carbonate) pool is 2-10 times larger than SOC pool ( Yang et al, 2010 ; Wang et al, 2015 ; Zhang et al, 2015 ; Guo et al, 2016 ), and its content and distribution are affected by soil moisture, temperature, depth, salinity, pH, soil type, and parent rock ( Raza et al, 2020 ; Song et al, 2021 ; Naorem et al, 2022 ). Especially, in desert ecosystems with sparse vegetation, the increase in soil pH and salinity is conducive to carbonate mineral formation ( Gong et al, 2016 ).…”