Date: 2013-06-28

Degree: Doctoral Thesis

Programme: Bachelor of Philosophy

Authors: Aruomero Solomon Amuno

Supervisors: Doctor Emilie Tran, University of Saint Joseph

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Abstract:

In 1994, Rwanda experienced the outbreak of a genocide violence that resulted in the systematic massacre of about 800,000 people within 100 days. Carrying out proper burial for the exponential number of people killed posed significant challenges to the Rwandan people due to existing land scarcity problems. With no other effective burial alternatives at sight, and in consideration for public health, remains of the genocide victims were disposed in shallow mass graves across the country. However, in recent years the use of these shallow mass graves has engendered serious ecological and epidemiological concerns. Despite such concerns, no empirical investigations have been carried out to determine if shallow mass graves are potential sources of environmental contamination. Soil and ground water contamination potential of cemeteries have been investigated in many parts of the world, but till date no extensive studies exist that examine the extent to which post-conflict mass graves are sources of pollution, particularly in the context of sub-Saharan Africa. The purpose of this thesis is to preliminarily investigate the geochemical properties and contamination potential of soils associated with selected genocide mass graves in Rwanda. This study utilized geochemical quantitative methodology to preliminarily ascertain the degree of soil contamination associated with two post-conflict mass graves in Rwanda, namely the Gisozi Memorial sites and Murambi memorial site. On the other hand, focus group analysis was also used to preliminarily elicit public perception regarding the potential environmental threats likely to be posed by the selected mass graves. The following are the major research findings of the investigations:

  1. Kigali site (Gisozi Memorial site): geochemical assessment of the soils associated with the genocide cemetery indicated that onsite mean concentration for twelve selected trace elements (As, Ba, Cr, Cs, Ga, Ni, Rb, Sc, Th, V, Y, and Zr) were generally higher than their offsite background values. The genocide cemetery soils showed higher contamination ratio for four trace elements (As, Cr, Ni, and Sc) relative to Clarke values (world averages for soils). The soils also exhibited significant enrichment with two priority pollutant metals (As and Cr) in comparison with world averages for agricultural soils.
  2. The quantitative assessment of the overall contamination degree (Cdeg) and potential ecological risks status (RI) of the necrosols (cemetery soils) for the Gisozi site indicated that the associated soils were only contaminated to a low degree. The cumulative trace metal content of the soils does not pose any significant ecological risks.
  3. The exchangeable sodium percentage (ESP %) for the Gisozi soils indicated that most of the onsite soil samples are sodic and likely to have adverse effect on the growth and yield of crops grown in the study area.
  4. For the Murambi site, soils from two excavated mass graves were similarly analyzed for their trace element contents. The enrichment factor (EF), chemical index of alteration (CIA) and overall contamination status of the necrosols samples was determined. The results revealed that average EF values for both onsite and offsite samples were generally within the class of natural background. From the resulting pollution index values (PNemerow) it was determined that the contamination of the soils were within the range of 0.89 and 1.82 corresponding to low contamination or the “the precaution to slightly polluted” domain.
  5. The composition of rare-earths elements (REE) and major oxides in soils of the Gisozi mass graves in Rwanda were compared to that of a municipal cemetery located in Akure, Nigeria. The results revealed that the cemetery soils of the Akure site and Kigali were more enriched in REE contents than their respective background areas. The chondrite normalized La/Yb ratios for the Akure cemetery soils ranged from 32.3 to 52.8, while that from the Kigali site ranged from 8 to 11.7. This suggests that Akure soils have  higher LREE (Light rare earth elements) and lower HREE (Heavy rare earth elements) contents, resulting in a relatively higher degree of LREE/HREE fractionation. It was also observed that REE contents of the study areas, particularly the Kigali area exceeded the average REE contents of soils from Australia, Germany, Japan and China.
  6. Assessment of the responses collected from the focus group sessions unraveled some of prevailing factors affecting public perception and institutional attitudes towards contamination issues from mass graves. Some of the key factors include: lack of public awareness, traumatic past experience and general skepticism towards the subject.
  7. In addition, it was observed that current institutional framework for managing the conditions of genocide mass graves in Rwanda lacks a solid environmental component to address and possibly mitigate potential pollution issues.

The findings of this investigation generally suggest the selected post-conflict mass graves have not caused significant pollution, with reference to surface soils of the selected sites and surrounding areas. The findings showed that trace element contents of the soils are within safety threshold, except for a few locations that showed slight elevated concentrations. In order to adequately combat potential hazards posed by mass graves in Rwanda a comprehensive policy approach was recommended. The overall results generated from this investigation contribute new scientific information to the subject of necrosols (anthropogenic soils in cemetery vicinities), particularly in the context of mass graves. This research is also the first empirical work that examined the geochemical properties of mass grave soils in Rwanda and Africa at large. The results generated from this studies also advances and complements the earlier works of Zychoswki (2011); Spongberg and Becks (2000); Jonker and Olivier (2012); Majgier and Rahamonov (2012), Charzynski et al (2011); and Sobocka (2004).