Dataset mesocosm experiment biochar-sediment-plant

The sediment contamination as a consequence of human activities is a widespread environmental problem, affecting a variety of natural and artificial basins. The dredging of these sediments produces large amounts of polluted materials, that require adequate management, especially when designated for reuse or relocation. In these cases, environmental functional materials, such as biochar, can be used to prevent sediments from becoming a secondary source of environmental pollution. In this context, we evaluated in a mesocosm experiment the biochar-assisted remediation of heavy metal-polluted, phytotoxic sediment. Considering that vegetation colonization often occurs when sediment is reused or relocated, we tested the combined effect of biochar amendment and plant growth (shrubs and perennial grass species) on the processes possibly leading to environment pollution, such as the persistence of phytotoxic compounds, the release of CO2 and nitrogen compounds in the environment and the transfer of metals to plant tissues. Natural attenuation of sediment phytotoxicity occurred independently from biochar amendment during the experiment. Similarly, because of the very low bioavailability of metals in the sediment, translocation to plant biomass was low and not affected by the biochar. On the other hand, the lowest dose of biochar (3%) reduced the CO2 emissions of the substrate, the substrate carbon loss, and the amount of nitrogen released into the environment. These effects disappeared at higher biochar doses, possibly because of the substrate warming related to the low albedo of the biochar, that stimulated organic matter mineralization. Finally, shrub growth in combination with the low dose of biochar was able to offset the CO2 emission of the sediment. These results indicate that biochar can be incorporated at the dose of 3% w/w in organic matter-rich sediments to reduce the release of carbon and nitrogen in the environment.