The Application of Dendrochemistry to Assess Recent Changes in Environmental Chemistry of Urban Areas

Dendrochemistry was applied to a small town, Taylorville, Illinois, which has a superfund site and apparently more cases of cancer than expected based on background rates. As an ecologic study, dendrochemistry is not intended to unequivocally associate particular elements to specific illnesses, but rather dendrochemistry serves more generally to characterize changes in element availability through time, which then might lead to follow-up epidemiological studies. In Taylorville, multiple elements measured in decadal chunks of tree rings of 12 trees showed no trend though time going back several decades. This non-result is important, demonstrating that element concentrations can remain constant across tree rings. By contrast, multiple other elements showed an uptick in concentration beginning by about 2000. Some of these elements are known to be harmful to human health, while others are not. More broadly, it could be of interest to consider increases through time in multiple metals as a combined burden in public health. Spatially, tree sampling for dendrochemistry is often not dense enough to isolate sources of element availability. Other techniques of environmental monitoring exist for elucidating spatial patterns of elements, and leaf surface chemistry is recommendable as a companion technique for dendrochemistry to discover spatial and temporal environmental patterns.