Identification of trace metals and potential anthropogenic influences on the historic New York African Burial Ground population: A pXRF technology approach

Carter K Clinton,Fatimah L C Jackson,Latifa Jackson,Richard K Shaw,Candice M Duncan

doi:10.1038/s41598-019-55125-7

Abstract

The New York African Burial Ground (NYABG) is the country’s oldest and largest burial site of free and enslaved Africans. Re-discovered in 1991, this site provided evidence of the biological and cultural existence of a 17th and 18th Century historic population viewing their skeletal remains. However, the skeletal remains were reburied in October 2003 and are unavailable for further investigation. The analysis of grave soil samples with modern technology allows for the assessment of trace metal presence. Portable X-ray fluorescence (pXRF) spectrometry provides a semi-quantitative and non-destructive method to identify trace metals of this population and in the surrounding environment. Sixty-five NYABG soil samples were analyzed on a handheld Bruker Tracer III- SD XRF with 40 kV of voltage and a 30μA current. Presence of As, Cu, and Zn can potentially decipher the influence of the local 18th Century pottery factories. Elevated levels of Sr validate the assumed heavy vegetative diets of poor and enslaved Africans of the time. Decreased levels of Ca may be due in part to the proximity of the Collect Pond, the existing water table until the early 19th Century, and Manhattan’s rising sea level causing an elevated water table washing away the leached Ca from human remains. These data help us reconstruct the lives of these early Americans in what became New York City.

Highlights

Grave soil, the decomposed substrate of living organisms, is characterized by the presence of mineral remains present in the living organism and as such is used as a resource for forensic and anthropological studies
This paper describes a Portable X-ray fluorescence (pXRF) approach for the analysis of trace metals (i.e. As, Ca, Cu, Sr and Zn) in cadaveric New York African Burial Ground (NYABG) soils and establishes a feasible protocol for similar research projects involving historic human remains
We only reported on the five elements that had accurate or certified values from the NYABG samples, control samples and National Institute of Standards and Technology (NIST) Standard reference materials (SRMs) data sets

Summary

Introduction

The decomposed substrate of living organisms, is characterized by the presence of mineral remains present in the living organism and as such is used as a resource for forensic and anthropological studies. Studies have demonstrated the accuracy of pXRF suggesting its efficacy in trace metal detection to be consistent with chemical analyses such as ICP-MS (inductively coupled mass spectrometry) and AAS (atomic absorption spectrometry)[8,9,10,11,12,13,14,15,16,17,18] This technology (pXRF) was chosen for its non-destructive nature and the finite availability of these 17th and 18th-century grave soils samples. Descriptions of each burial were provided in the initial reports generated shortly after the excavation by Howard University and General Services Administration (GSA) These reports detailed the skeletal biological, archaeological, and historical analyses of the NYABG23. The findings of this investigation enrich the fields of archaeology, anthropology, and soil chemistry

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