Nitrogen levels in long bones from coffin burials interred for periods of 26-90 years

Samples of long bones were obtained from 42 bodies buried in coffins at two sites over a 26 to 93 year period. Quicklime had been added to 17 of the coffins and there was fuel oil contamination of three of these. Long bone total nitrogen levels obtained by the macro Kjeldahl method were subjected to statistical analysis and their distribution plotted on a graph of burial time versus bone total nitrogen content. The highest nitrogen level recorded was 4.06 g per 100 g of bone (26 years) and the lowest 3.27 g per 100 g of bone (80 years). The oldest burial (93 years) gave a total nitrogen level of 3.49 g per 100 g of bone. For practical purposes, for burials deeper than 4 ft, the rate at which nitrogen is lost is independent of depth of burial. Although the overall trend was for nitrogen content to decrease with age, it was noted that despite being the oldest of the burials, the quicklime burials still possessed a relatively high nitrogen content. The maintenance of a relatively high nitrogen content in the quicklime burials was thought at first to be due to the quicklime acting as an inhibitor of decomposition during the initial period of interment. Statistical analysis, however, showed there to be no correlation between the addition of lime and the bone nitrogen level. Fuel oil contamination of three of the skeletons led to a high nitrogen content being recorded in the long bones, giving the impression that those burials were more recent than they actually were.