Metals conservative behaviour

Calculations by Kerdijk (1931) of dispersion processes indicated that chloride, showing conservative behaviour, will appear in the adjacent polders in approx, the year 2100, the heavy metals 1-3 centuries, and pesticides several thousand years later. 

The distributions of Group 17 elements (Fig. 12.12) are most closely comparable to those of the weakly interactive Group 1 elements. F, Cl and Br are conservative elements. The halides interact strongly with a number of Periods 4 and 5 metals between Groups 8 and 15. However, these metals have seawater concentrations very much lower than H, Br, Cl- and F and, thereby, do not significantly influence the distribution and chemical behaviour of the latter elements. 

The chemistry of dissolved metals in seawater can be grouped into three classes, which describe the behaviour of the metal during chemical cycling. These classes—conservative, nutrient-like and scavenged—have been recognized by the shapes of concentration profiles when plotted against depth in the oceans. 

Methods of obtaining the metal or alloy from its ores will be briefly covered here as with the possible shaping processes to produce the finished object. The corrosion behaviour of the metal while buried will also be discussed and this will be related to various methods available in the conservation of these materials. 

Corrosion of metallic heritage artefacts investigation, conservation and prediction of long-term behaviour... 

Polymers have been shown to affect the deterioration of objects where they have been studied, e.g. paper (Baer et al., 1976), canvas (Berger and Zeliger, 1975) and metals (Williston, 1982). The object can in principle make an enormous difference to the ageing behaviour of the applied polymer. However, this seems to have been noticed in only a few cases. Most objects in conservation are old ones and have themselves started to degrade to some extent. Cellulose rapidly... 

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