CO2leakage from carbon dioxide capture and storage (CCS) systems affects organic matter cycling in surface marine sediments.
Carbon dioxide capture and storage (CCS), involving the injection of CO2into the sub-seabed, is being promoted worldwide as a feasible option for reducing the anthropogenic CO2emissions into the atmosphere. However, the effects on the marine ecosystems of potential CO2leakages originating from these storage sites have only recently received scientific attention, and little information is available on the possible impacts of the resulting CO2-enriched seawater plumes on the surrounding benthic ecosystem. In the present study, we conducted a 20-weeks mesocosm experiment exposing coastal sediments to CO2-enriched seawater (at 5000 or 20,000 ppm), to test the effects on the microbial enzymatic activities responsible for the decomposition and turnover of the sedimentary organic matter in surface sediments down to 15 cm depth. Our results indicate that the exposure to high-CO2concentrations reduced significantly the enzymatic activities in the top 5 cm of sediments, but had no effects on subsurface sediment horizons (from 5 to 15 cm depth). In the surface sediments, both 5000 and 20,000 ppm CO2treatments determined a progressive decrease over time in the protein degradation (up to 80%). Conversely, the degradation rates of carbohydrates and organic phosphorous remained unaltered in the first 2 weeks, but decreased significantly (up to 50%) in the longer term when exposed at 20,000 ppm of CO2. Such effects were associated with a significant change in the composition of the biopolymeric carbon (due to the accumulation of proteins over time in sediments exposed to high-pCO2treatments), and a significant decrease (∼20-50% at 5000 and 20,000 ppm respectively) in nitrogen regeneration. We conclude that in areas immediately surrounding an active and long-lasting leak of CO2from CCS reservoirs, organic matter cycling would be significantly impacted in the surface sediment layers. The evidence of negligible impacts on the deeper sediments should be considered with caution and further investigated simulating the intrusion of CO2from a subsurface source, as occurring during real CO2leakages from CCS sites.
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, 60131, Italy; Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, 80121, Italy.
Eugenio
E
Rastelli
Department of Sciences and Engineering of Materials, Environment and Urbanistics, Polytechnic University of Marche, Ancona 60131, Italy.
Cinzia
C
Corinaldesi
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, 60131, Italy.
Antonio
A
Dell'Anno
Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, 80121, Italy; Norwegian Institute for Water Research (NIVA), Regional Office Bergen, Bergen, N-5006, Norway.
Teresa
T
Amaro
Istituto Superiore per la Ricerca Ambientale, ISPRA, Roma, Italy.
Silvestro
S
Greco
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, 60131, Italy; Ecoreach srl, Corso Stamira 61, 60122, Ancona, Italy.
Marco
M
Lo Martire
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, 60131, Italy; CoNISMa, Piazzale Flaminio 9, 00197, Roma, Italy.
Laura
L
Carugati
Plymouth Marine Laboratory, Prospect Place, Plymouth PL1 3 DH, United Kingdom.
Ana M
AM
Queirós
Plymouth Marine Laboratory, Prospect Place, Plymouth PL1 3 DH, United Kingdom.
Stephen
S
Widdicombe
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, 60131, Italy; Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, 80121, Italy. Electronic address: r.danovaro@univpm.it.
Roberto
R
Danovaro
D002244:Carbon; D002245:Carbon Dioxide / Q000032:analysis; D057965:Carbon Sequestration; D055669:Ecological and Environmental Phenomena; D017753:Ecosystem; D004784:Environmental Monitoring; D019015:Geologic Sediments; D012623:Seawater; D014874:Water Pollutants, Chemical / Q000032:analysis
D014874:Water Pollutants, Chemical; D002245:Carbon Dioxide; D002244:Carbon
Biogeochemical cycles; CO(2) impact on benthos; Carbon storage; Remineralization; Seawater acidification