Page 192 - Manual for Activities directed at the Underwater Cultural Heritage

 the mound without disturbing the fill strata. Researchers also used frozen samples of wood and wood suspended in the open water column as control groups. One year after sealing the mound, the dissolved oxygen level fell to 1 mg/liter and has held constant.The dissolved oxygen of the water around the mound has tested from 9 to 10 mg/liter consistently. Other chemical properties tested include sulfide, alkalinity, pH, nitrate, ammonia, nitrite, total phosphorous, silicate, and iron. These tests have illustrated that the reburial environment is a reducing one.
emergence of preventive in situ conservation. Nevertheless, if the decision is taken to leave artefacts on site, some precautions must be taken regarding the further degradation of the artefacts as well as the risk of looting.
 Three major approaches for in situ treatment are viable, which may be classed according to the materials being protected:
1. an organic heritage approach favouring reburial of a site and follow-up over time consisting of probing, studying and excavating followed by reburial and subsequent monitoring of the remaining site;
2. the built heritage approach, which first en- gages in preventive conservation and restoration work, but ultimately focuses on the creation of underwater archaeological parks;
Immediately after recovery, finds shall be kept:
• waterlogged : fragile objects shall preferably be kept in water from the original location while more robust objects can gradually undergo freshwater baths in order to start the desalination process
• cold
• in the dark
• in inert containers
• labelled
• separated according to materials of composition
• with great safety : weapons and potentially explosive
materials should be handled with considerable caution and according to safety regulations
 © PROAS - INAPL. An unidentified shipwreck, Chubut, Patagonia, Argentina.
An unidentified wooden shipwreck (known as Bahía Galenses II) attributed to the second half of the 19th century, located in the intertidal zone
of Puerto Madryn (Chubut, Patagonia, Argentina), was covered with sand bags for in situ protection. Members of the local community participated in this task.
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Conservation and site management