Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO₂ that adds up with dissolved inorganic carbon (dissolved CO₂, H₂CO₃, HCO₃⁻, and CO₃²⁻) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO₂ itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena

Balance and Behavior of Carbon Dioxide at an Urban Forest Inferred from the Isotopic and Meteorological Approaches

From the 17th International Radiocarbon Conference held in Jerusalem, Israel, June 18-23, 2000.Diurnal variations in δ14C, delta-13C and the concentration of atmospheric carbon dioxide in an urban forest were measured on 9 February 1999 to discriminate and quantify contributions from different CO2 sources. The biogenic CO2 concentration remained relatively constant throughout the day. However, anthropogenic CO2 concentration fluctuated with the atmospheric CO2 concentration, and seemed to be controlled by wind velocity and the amount of exhaust gases from fossil fuel burning. The vertical profiles of anthropogenic, biogenic, and total CO2 showed a constant concentration within forest during daytime because of the large vertical CO2 influx, strong winds, and neutral atmospheric condition. The biogenic contribution at night decreased from the forest floor upwards with a smooth gradient, while the anthropogenic contribution showed a direct mirror because of the location of respective CO2 sources—the vertical gradient of wind velocity and the horizontal CO2 supplyThe Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202