Characterizing the preservation potential of buried marine archaeological sites

Abstract

The preservation potential of sediments from a submerged prehistoric site buried in a full marine environment was assessed using a combination of direct in situ measurements, measurements on extracted sediment cores and laboratory mesocosm experiments. The results show that first and foremost it is paramount to ascertain the state of preservation of the materials in the seabed—in this case wooden artifacts—that are to be preserved in situ. The results suggest that dissolved oxygen and sulfide are good parameters to measure in situ to assess the general oxidizing or reducing nature of the environment. If it is possible to take sediment core samples, it is similarly important to measure dissolved oxygen and hydrogen sulfide in the core and extract pore water to assess for sulfate content. Sediments should be characterized for particle size, water content (porosity) and organic content. In this way, we show that dissolved oxygen was rapidly depleted in the first few centimeters of sediment, thereafter sulfate reduction dominated the geochemical processes. Coarser sediment types with high porosity and low organic content have lower rates of organic material turnover, indicating better preservation conditions.