Preservation of organic carbon in marine sediments sustained by sorption and transformation processes.

Controls on organic carbon preservation in marine sediments remain controversial but crucial for understanding past and future climate dynamics. Here we develop a conceptual-mathematical model to determine the key processes for the preservation of organic carbon. The model considers the major processes involved in the breakdown of organic carbon, including dissolved organic carbon hydrolysis, mixing, remineralization, mineral sorption and molecular transformation.

Long-term organic carbon preservation enhanced by iron and manganese.

The balance between degradation and preservation of sedimentary organic carbon (OC) is important for global carbon and oxygen cycles. The relative importance of different mechanisms and environmental conditions contributing to marine sedimentary OC preservation, however, remains unclear. Simple organic molecules can be geopolymerized into recalcitrant forms by means of the Maillard reaction, although reaction kinetics at marine sedimentary temperatures are thought to be slow.

Coastal El Niño triggers rapid marine silicate alteration on the seafloor.

Marine silicate alteration plays a key role in the global carbon and cation cycles, although the timeframe of this process in response to extreme weather events is poorly understood. Here we investigate surface sediments across the Peruvian margin before and after extreme rainfall and runoff (coastal El Niño) using Ge/Si ratios and laser-ablated solid and pore fluid Si isotopes (δSi). Pore fluids following the rainfall show elevated Ge/Si ratios (2.

Bioturbation and the δFe signature of dissolved iron fluxes from marine sediments.

We developed a reaction-transport model capable of tracing iron isotopes in marine sediments to quantify the influence of bioturbation on the isotopic signature of the benthic dissolved (DFe) flux. By fitting the model to published data from marine sediments, we calibrated effective overall fractionation factors for iron reduction (-1.3‰), oxidation (+0.

Simulating and Quantifying Multiple Natural Subsea CO Seeps at Panarea Island (Aeolian Islands, Italy) as a Proxy for Potential Leakage from Subseabed Carbon Storage Sites.

Carbon dioxide (CO) capture and storage (CCS) has been discussed as a potentially significant mitigation option for the ongoing climate warming. Natural CO release sites serve as natural laboratories to study subsea CO leakage in order to identify suitable analytical methods and numerical models to develop best-practice procedures for the monitoring of subseabed storage sites. We present a new model of bubble (plume) dynamics, advection-dispersion of dissolved CO, and carbonate chemistry.

Microbial Sulfide Filter along a Benthic Redox Gradient in the Eastern Gotland Basin, Baltic Sea.

The sediment-water interface is an important site for material exchange in marine systems and harbor unique microbial habitats. The flux of nutrients, metals, and greenhouse gases at this interface may be severely dampened by the activity of microorganisms and abiotic redox processes, leading to the "benthic filter" concept. In this study, we investigate the spatial variability, mechanisms and quantitative importance of a microbially-dominated benthic filter for dissolved sulfide in the Eastern Gotland Basin (Baltic Sea) that is located along a dynamic redox gradient between 65 and 173 m water depth.