Experiments on the influence of sediment disturbances on the biogeochemistry of the deep-sea environment

In experiments with large undisturbed sediment cores, stirring the upper centimeters of sediment immediately released dissolved pore-water constituents such as heavy metals and nutrients. Rapid scavenging in the suspension after the disturbance was observed for cationic particle-reactive metals like Mn, Co, Ni, Zn, Cu, Cd, Pb, and Fe, while anionic metal species like Mo, V, and U showed neither strong release nor sorption. Microbial activity, fresh particulate organic carbon and nitrogen, and amino acids and hexosamines increased during the first days after disturbance. The ratios of C and N and of the amino acids also changed with time. Applicability of the results of laboratory experiments to in situ deep-sea conditions supports the necessity of in situ experiments in benthic chambers.