AbstractThe characterization of particles in suspension in river plumes contributes to the assessment of net particulate organic carbon (POC) fluxes and to a better understanding of the anthropogenic and climatic impact on blue carbon. Prior to POC analysis in natural waters, inorganic carbon (in the form of carbonates) must be removed. This step is generally carried out by acid leaching. However, the presence of mineral matrices (in turbid waters) may hinder total decarbonation, which may result in biased measurements. This work checks the quality of decarbonation through the analysis of carbon stable isotope ratio (δ13C), considering suspended particles discharged by three rivers into coastal waters under flooding conditions. Carbonates were removed by adding variable volumes of 2N hydrochloric acid (HCl) to filters. Carbon concentrations and stable isotopic ratios were analyzed. Values of δ13Corg (stable isotope ratio of organic carbon) allow the identification of incompletely decarbonated samples. If a small amount of detrital carbonates resists the usual decarbonation treatment, δ13Corg can be significantly shifted towards less negative values, suggesting the need of more efficient decarbonation methods in order to improve the accuracy of organic carbon measurements. Even in the case of a high Corg/Ctotal ratio, the impact of remaining carbonates on the δ13Corg value is strong because δ13Cinorg is significantly different. The sensitivity of δ13Corg measurement might therefore be used to validate POC measurements in estuarine and coastal waters.
A Dual-Carbon-and-Nitrogen Stable Isotope Ratio Model Is Not Superior to a Single-Carbon Stable Isotope Ratio Model for Predicting Added Sugar Intake in Southwest Virginian Adults
