The simple techniques employed here have helped formulate a management plan for the Kinlochbervie site.
Despite this success, it is clear that there is a lot we do not understand about the site. The contradiction between the corrosion rate measurement (indicating very slow corrosion) and the deterioration of the iron artefacts (in extreme states of decay) clearly requires further study.
One of the main problems in drawing conclusions from site monitoring is that the monitoring experiment is of short duration. The corrosion rate studies were carried out over a period of a little over a year - about one four-hundredth of the age of the site.
To counterbalance this we have compared results from 'spot tests' with the condition of the artefacts. There is one other source of information available to us that should accurately reflect the conditions on the site; the sea life.
We have very little doubt that most chemical processes in the marine environment are mediated by microbiological organisms. These chemical processes will include the deterioration of the materials that artefacts are made of. Unfortunately micro-organisms at the level of bacteria and fungi are difficult to identify and quantify without specialist equipment. The question we pose here is whether or not the macrobiology, which we do have a chance of being able to identify and quantify, also reflects prevailing chemical and physical conditions.
Taking into account the macro-biology, on the Kinlochbervie site we are able to identify a second anomaly. The hard substrate that makes up the site would normally be ideal for colonisation by sessile animals, such as dead men's fingers and anemones. Very few such organisms are present, however. We ascribe this absence to the lack of currents required to bring food to animals that cannot actively hunt it down.
This supports earlier conclusions, but how does a slow current flow translate into poor preservation for iron? One possibility is that concretion formation may be associated with current flow. The delivery of calcium ions to the iron surface and the removal of the acid formed by the corrosion process will both be current dependent. Both transport processes will also have an impact on concretion formation, irrespective of whether this is a simple chemical precipitation or a more complex biologically mediated process.
The study at Kinlochbervie brought home to us the importance of looking at sites holistically. We have subsequently entered into a dialogue with members of the Marine Conservation Society, in order to bring their expertise in biological survey techniques to bear on the problem of analysing the complex marine environment that is a shipwreck.