Carter Clinton’s team uncovers unique chemical signatures in African Burial Ground grave soils

Throughout the 2017 summer months, Howard University Ph.D. student Carter Clinton (pictured on the right) has conducted an ongoing investigation of New York African Burial Ground grave soil samples. Specifically, he has looked into the elemental analysis of these samples . Carter has been fortunate to run these data at the University of Maryland, College Park under the direction of expert soil chemist and lecturer, Dr. Candice Duncan. The investigation consists of using x-ray fluorescence (XRF) technology, a non-destructive exploratory technology, to identify all elements present in a sample. The methodology calls for a small amount of required sample (2 grams) to be compressed into pellet form with a binding agent that won’t interfere with analysis, in this case, urea. The small sample mass is carefully considered because the quantity of these grave soils are extremely limited. The remaining portion of each sample can then be used in other important analyses as well as for archival purposes.

The data generated from the XRF device is compared with several NIST (National Institute of Standards and Technology) SRMs (Standard Reference Materials). After purchasing an initial SRM, Carter and Dr. Duncan reached out to NIST for background information of the standard. This conversation and the interest in the NYABG project prompted an invitation for the two, to the NIST Gaithersburg facility as well as a donation of four additional SRMs to contribute toward the research. While at the NIST facility, Dr. John Sieber, ran an analysis of the grave soil sample on their government regulated XRF device and has extended an invitation to Carter to return in the future to run the remaining samples on this equipment. This opportunity will validate and verify that the results obtained from the XRF device at UMD are accurate.

In addition, to comparing the results of our UMD XRF to NIST reference material, we have reached out to Dr. Richard Shaw, USDA state soil scientist, who has performed a soil survey of New York City. These data can be considered control samples used for comparison with the NYABG samples. Carter and his team will be able to determine baseline levels of elements in the soil as well as significant levels of elements in the ABG soil. This comparison will provide insight in to what activities were performed by the inhabitants in the area. From this, we can reconstruct events occurring during the 17th and 18th centuries in lower Manhattan. ****

Cobb Lab