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.

人类活动导致的沉积物污染是一类广泛分布的环境问题，波及各类自然与人工汇水盆地。对这类沉积物进行疏浚作业会产生大量污染物料，需采取妥善的管理措施，尤其当这些物料计划用于再利用或异地处置时。在此类场景中，生物炭（biochar）等环境功能材料可用于阻止沉积物成为二次环境污染源。在此研究背景下，本研究通过中宇宙（mesocosm）实验评估了生物炭辅助修复重金属污染且具植物毒性沉积物的效果。考虑到底泥在再利用或异地处置过程中通常会发生植被定植，我们测试了生物炭施加与植物生长（灌木及多年生草本物种）的联合作用对可能引发环境污染的过程的影响，包括植物毒性化合物的留存、环境中CO₂与氮化物的释放，以及金属向植物组织的迁移过程。实验期间，沉积物植物毒性的自然衰减过程与生物炭施加无关。同理，由于沉积物中金属的生物有效性极低，其向植物生物量的转移量较低，且不受生物炭施加的影响。另一方面，最低剂量的生物炭（3% w/w）可降低基质的CO₂排放、基质碳损失以及释放至环境中的氮素总量。该效应在更高剂量的生物炭施用量下消失，这可能是因为生物炭的低反照率导致基质升温，进而刺激了有机质矿化过程。最后，灌木生长与低剂量生物炭的联合作用可抵消沉积物的CO₂排放。上述结果表明，可将生物炭以3% w/w的剂量混入富含有机质的沉积物中，以降低碳与氮向环境中的释放量。