Geochemical Assessment of Two Excavated Mass Graves in Rwanda: A Pilot Study

Abstract

Necrosols are a unique category of anthropogenic soils that are associated with excavated cemeteries or graveyards. In spite of the growing number of cemeteries and burial sites found across urban and rural areas globally, scientific information regarding the contamination potential of this category of soils is relatively scarce and not properly understood. The purpose of this study is to fill this gap by assessing the contamination significance of trace metal contents in the necrosols associated with two excavated mass graves in Rwanda. For this preliminary geochemical investigation, cemetery soil samples were collected from two excavated mass graves in the Murambi memorial site, Rwanda, and analyzed for trace and major element concentrations. The enrichment factor (EF), chemical index of alteration (CIA), and contamination status of necrosol samples was determined in comparison with the offsite area. The results revealed that the average EF values for both onsite and offsite samples were generally within the class of natural background with only six onsite samples having higher EF values than the offsite or background area. Possible reasons for the progressive depletion of the selected trace element onsite are the relatively low anthropogenic activities and higher weathering intensity of the necrosols in comparison with the background area over time. Even though the mean onsite CIA values for the necrosols were slightly higher than the background area, the index further confirmed that both the necrosols and offsite samples were significantly altered to kaolinic degree. From the resulting pollution index values (PI Nemerow ), it can be inferred that the Murambi necrosols were within the range of 0.84 and 1.82, corresponding to the precaution and slightly polluted domain. The current contamination status of the necrosols is likely to have been caused as a result of the anthropogenic input of Cr and Pb onsite relative to the offsite area.

Metals in the soil of urban cemeteries in Carazinho (South Brazil) in view of the increase in deaths from COVID-19: projects for cemeteries to mitigate environmental impacts

“…The soils of cemeteries A, B and C were collected, in 5 internal points and in the external area of the cemeteries spaced every 100 m. The soils were sampled at two depths, from 0 to 20 and 20 to 40 cm; with three levels of repetition, totaling 180 samples between the cemeteries A, B and C to evaluate the concentrations of Fe, Mn, Cu, Zn, Cr and Pb (g kg −1 ), which were found to be more prevalent in studies involving the soil of cemeteries (Amuno & Amuno, 2013 ; Jonker & Olivier, 2012 ; Kemerich et al, 2014 ; Natali et al, 2016 ; Neckel et al, 2016 , 2021 ; Neira et al, 2008 ; Shafer et al, 2008 ; Silva et al, 2020 ; Spongberg & Becks, 2000 ), with the exception of iron, was not analyzed among these studies.…”

“…This aspect refers to the prediction analysis of COVID-19 deaths to obtain the world parameters of burials. The incidence of fatal cases of COVID-19 justifies rethinking the structure of cemeteries, so that they can account for the concentration of metals deposited in the soil (Amuno & Amuno, 2013 ; Jonker & Olivier, 2012 ; Kemerich et al, 2014 ; Natali et al, 2016 ; Neckel et al, 2016 , 2021 ; Neira et al, 2008 ; Shafer et al, 2008 ; Silva et al, 2020 ; Spongberg & Becks, 2000 ). A seasonal univariate modeling time series using autoregressive integrated moving average (ARIMA) was applied.…”

“…In this context, urban cemeteries have become a global problem, due to the phenomenon of urban expansion that increasingly brings development and urbanization to these locations, surrounding a formerly distant cemetery with dense residential areas, thus leaving this population exposed to contamination by metals, such as zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), chromium (Cr), nickel (Ni), lead (Pb) and cadmium (Cd) (Amuno & Amuno, 2013 ; Jonker & Olivier, 2012 ; Kemerich et al, 2014 ; Natali et al, 2016 ; Neckel et al, 2016 , 2021 ; Neira et al, 2008 ; Shafer et al, 2008 ; Silva et al, 2020 ; Spongberg & Becks, 2000 ). The main characteristics of this study in relation to other studies are a scenario unseen for the past century on a global scale.…”

Animal carcass burial management: implications for sustainable biochar use

“…This leachate is characterized by high BOD, pH, conductivity and chemical compounds including phosphorus, nitrogen, Na + , Ca 2+ , Cl − , , and 10% organic compounds [ 18 , 53 ]. Necrosols also have the possibility to be contaminated with heavy metals such as Pb, Cr, Zn, As, Mo, and Cu through the decomposition of paints, preservatives and metallic components from coffins [ 54 , 55 ] Amuno [ 31 ] found slightly higher concentrations of 12 trace elements (As, Ba, Cr, Cs, Ga, Ni, Rb, Sc, Th, V, Y, and Zr) in soil of mass grave sites in Rwanda compared to offsite soils. However, that study revealed that the elemental concentrations were not great enough to generate any environment concern.…”

Estudio de Necrosoles y suelos de cementerio

“…En el estudio de suelos de fosas comunes excavadas en Ruanda, encuentran que las concentraciones media y máxima en los sitios de arsénico (As), bario (Ba), cromo (Cr), cesio (Cs), galio (Ga), níquel (Ni), rubidio (Rb), escandio (Sc), torio (Th), vanadio (V), y zirconio (Zr), son generalmente más altas que sus valores fuera del sitio y que los contenidos de metales traza de los suelos del cementerio presentan una mayor proporción de acumulación para ciertos elementos, particularmente As, Cr, Ni y Cs en relación con los promedios mundiales para los suelos [17,18] Además, el estado de contaminación actual de los Necrosoles como resultado de la entrada antropogénica de Cr y Pb por los proyectiles de bala presentes en los cráneos sepultados en el sitio; es de particular interés para estos estudios, la cantidad de sales solubles, específicamente de sodio, que también pueden proliferar causando la sodicidad del suelo [19][20].…”