Artisanal Mining and Soil Quality in the Sudano-Sahelian Climate: Case of the Artisanal Mining Site of Yimiougou in Burkina Faso, West Africa

The majority of the population of Burkina Faso lives from agriculture and therefore depends on the land. The main objective of this study is to assess the quality of the soils in the area linked to artisanal mining activities. The methodology adopted consisted in sampling and characterizing the main types of soil. In order to assess the level of soil pollution by artisanal mining, parameters such as the geo-accumulation index (Igeo) and the contamination factor (CF) are calculated. A prediction of acid mine drainage (AMD) was also carried out on samples of mine tailings which are potential sources of pollution of these soils. The results obtained show that the soils in Yimiougou are of nil to low agronomic interest. The Igeo shows that for lead, copper, zinc and arsenic the levels found in the different morphological units are partly attributable to human action and specifically artisanal mining. The values of the contamination factor indicate contamination. Cobalt presents the lowest contamination. For cadmium, the different types of soil are moderately contaminated except for the FITLC type, which has a CF value of 0.50, therefore synonymous with low or absent contamination. The various morphological units studied are very heavily contaminated with zinc, copper, lead and arsenic. The pH and conductivity values indicate that the mine tailings samples are non-acidogenic, therefore not yet oxidized. As for the sulphide contents, they show that only samples S17, S22, S23 and S24 present values that are strictly above the threshold (0.3%) and therefore potentially acid-generating. The comparative study of the acid potential (AP) and the neutralization potential (NP) reveals that the neutralization potentials of the different samples are clearly higher than the acid potentials even for the samples which present a proven acidification potential (S17, S22, S23 and S24). These results show that the mine tailings have the natural capacity to neutralize any possible mine drainage, given the presence of acid-eating minerals such as the carbonates associated with the mineralization.

Assessment of Natural Radioactivity in Rivers Sediment and Soil from the Copper Belt Artisanal Mining Region, Democratic Republic of the Congo

The concentrations and distribution of naturally occurring radionuclides (238U, 235U, 234U, 230Th, 226Ra, 210Pb, 232Th, 228Ra, and 40K) were determined by alpha and gamma spectrometry in soil and sediments collected from Luilu and Dilala rivers located in the mining district of Kolwezi (Lualaba Province) of the Democratic Republic of the Congo. The average concentrations of 238U and 226Ra in the analyzed samples were 5 - 10 times higher than the world average values for soil provided by the United Nations Scientific Committee on the Effects of Atomic Radiation. However, the average concentrations of 232Th were found similar to the world average. In both river basins, artisanal mining activities and mineral washing sites displayed the higher concentration values of radionuclides. The mean values of health risk indices calculated for those sites were found significantly higher compared to world average levels. Radiation protection measures seem needed to ensure the radiation safety of local populations. Graphical Abstract

Spatial distribution and potential ecological and health risks associated with heavy metals in the Ijero-Ekiti mining site,Nigeria

Artisanal gold mining,a labor-intensive and antiquated technique,is a growing industry and the source of income for rural communities all over the world.However,artisanal gold mining has potential negative and long-term effects on economy,environment,and society.This study collected soil samples from 16 sample points including a control point to examine the pollution degrees and spatial distribution of heavy metals,as well as ecological and health risks associated with heavy metal pollution in the Ijero-Ekiti mining site,Nigeria.Geographical Information System(GIS)and remote sensing technologies were used to identify regions with high concentrations of heavy metals and assess the environmental impact of gold mining activities.The results show that the mean heavy metal concentrations of 16 soil pointa are 8.94(±5.97)mg/kg for As,0.18(±0.54)mg/kg for Cd,0.11(±1.06)mg/kg for Co,14.32(±3.43)mg/kg for Cr,6.89(±0.64)mg/kg for Cu,48.92(±11.77)mg/kg for Fe,135.81(±30.75)mg/kg for Mn,5.92(±0.96)mg/kg for Ni,5.72(±1.66)mg/kg for Pb,and 13.94(±1.38)mg/kg for Zn.The study reveals that heavy metal concentration in soils follows the order of Mn>Fe>Cr>Zn>As>Cu>Ni>Pb>Co>Cd.An analysis of soil samples indicates that 3 principal components(PCs)account for 70.008%of the total variance and there are strong positive correlations between various pairs of heavy metals.The total potential ecological risk index(309.599)in the study area is high.Non-carcinogenic risk suggests that there may be long-term health impacts on people who work in the mining areas due to chronic exposure to the environment.Based on the study,the hazard index of carcinogenic health risks associated with heavy metals through ingestion is 520.00×10^(–4).Dermal contact from As and Cr also increases the risk of cancer,with the highest hazard index value of 18.40×10^(–4).The lowest exposure pathway,with the hazard index value of 0.68×10^(–4),indicates that the inhalation of heavy metals has a comparatively low risk of cancer.This study recommends the formulation of policies to monitor the Ijero-Ekiti mining site and other regions in Nigeria where indiscriminate artisanal gold mining activities exist.

Surface Water Sediments Characterization Using Metallic Trace Elements (MTEs): Case of the Artisanal Gold Mining Sites of Kokumbo (Côte d’Ivoire)

The main purpose of this study is to characterize the surface sediments of the Kokumbo artisanal gold mining sites in Metallic trace Elements (MTEs). A total of 12 samples of surface water sediments were collected for this study. The samples were analyzed using the Atomic Absorption Spectrophotometer (AAS). The mean concentrations of Mn (611.37 mg/kg) and Zn (955.86 mg/kg) in the sediments were very high compared to the standard in unpolluted sediments. The enrichment factor (EF) shows that there is an enrichment of Mn at some sites (EF (Mn) > 2). The presence of As, Mn, and Zn is also highlighted by the geo-accumulation index (I-geo) which shows slight pollution in Mn (0 < I-geo (Mn) < 1) on some sites. Moderate pollution for As (1 < I-geo (As) < 2) was determined at the treatment site and high pollution in Zn at some sites in the area (I-geo (Zn) > 3). This study shows that the presence of Zn in the sediments is linked to artisanal gold mining activities. Indeed, Zn is much used for gold recovery. The statistical analysis (PCA) shows, on the one hand, natural mineralization of the sediments and addition of metals linked to anthropic activities corresponding to the erosion of mining discharges. The surface sediments of the Kokumbo mining sites show pollution in As, Mn, and Zn.

Lead and Mercury Contamination Assoc=atea with Artisanal Gold Mining in Anka, Zamfara State, North Western Nigeria： The Continued Unabated Zamfara Lead Poisoning

A total of 24 soil samples were collected from areas around Artisanal Gold and associated Pb-Zn-Cu sulfide mining and mineral processing sites in the Anka mining district of Zamfara State, NW Nigeria. The samples were geochemically analyzed with the main objective of assessing the degree of Pb and Hg pollution in the environment resulting from the mining and mineral ore processing activities in the mining district and to consider the effect on human health. The assessment of the degree of pollution or toxicity was based on the Igeo （index of geoaccummulation） and EF （enrichment factor） where the former gives a quantitative pollution class with respect to the quality of the medium analyzed, while the latter differentiates between metals originating from anthropogenic activities and those from natural processes. The geochemical results show that the concentrations of Pb and Hg especially at the mineral processing sites significantly exceed the established thresholds （4,152 ppm and 12.92 ppm respectively）. The calculated EF values for both Pb and Hg revealed that the soils from the entire mining district are extremely enriched in these elements, essentially originating from the anthropogenic activities （EF= 〉〉 40）. Lead and Mercury are toxic heavy metals with documented long-lasting adverse human health effects. These calls for efficient bioremediation measures for the removal of Pb and Hg from the contaminated soils that take into account the geochemical peculiarities of the mining district.

Analysis of the Spatio-Temporal Evolution of Artisanal and Small-Scale Gold Mining in Central Ivory Coast, West Africa

Ivory Coast is a country rich in base metals and precious minerals: gold, manganese, diamond, iron, bauxite, cobalt and nickel. These natural resources are exposed to destruction and fragmentation by mining activities. The artisanal and small-scale exploitation of gold are increasingly practiced in our rural areas. These activities escape often in the control and monitoring of the mining administration. In order to better constrain these activities on the environment, the present work used remote sensing imageries to see its spatio-temporal impacts in the rural world in central Ivory Coast. The results show that gold artisanal activities have been practiced since 2013 and are experiencing an increasingly important growth. We note a devastation of forests and savannahs, a pollution of surface water, as well as an increase in poverty in rural areas. These activities are practiced near habited areas (villages). This creates a reduction of cultivatable soil. Remote sensing imageries make it possible to quickly map areas at large-scale gold mining in time and space.

Survival of Seedlings of Native Woody Species in the Rehabilitation of Gold Mined-Site within a Three Years Old Acacia mangium Willd Plantation of St. Elizabeth-Mahdia, Guyana

Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection. However, significant knowledge gaps exist regarding when and where to plant trees. This article reports on a revegetation trial undertaken in St Elizabeth, Mahdia, Guyana, to assess the survival and RGR (Relative Growth Rate) of three native woody trees and shrubs planted within three years old Acacia mangium Willd trees pruned and unpruned blocks. ANOVA (Analysis of Variance) for a completely randomized block design with four blocks, two pruned and two unpruned, within A. mangium plots. Biochar treatment was added to the plants during transplanting. Thirty-six (36) wildlings of Humiria balsamifera (Aublet.) (Tauroniro), Goupia glabra Aublet (Kabukalli), and Vismia guianensis (Aublet.) Choisy (Bloodwood) were collected and raised in a tree nursery for two weeks. The native plants were transplanted 3 m apart, survival observations and each seedling’s initial height and diameter were measured and recorded. After the experiment, 13% of seedlings from a population of 720 had died, with the highest mortality being experienced at the 92 days of the experiment (t ≤ 122 days). While the overall survival rates were high, emphasizing the importance of field trials on native and exotic species in different environments is essential to fill the knowledge gaps on suitable species for restoration in degraded areas with other land use histories.

Food contamination as a pathway for lead exposure in children during the 2010–2013 lead poisoning epidemic in Zamfara,Nigeria

In 2010, an estimated 400 to 500 children died of acute lead poisoning associated with artisanal gold mining in Zamfara, Nigeria. Processing of gold ores containing up to 10% lead within residential compounds put residents, especially children, at the highest risk. Principal routes of exposure were incidental ingestion and inhalation of contaminated soil and dusts. Several Nigerian and international health organizations collaborated to reduce lead exposures through environmental remediation and medical treatment. The contribution of contaminated food to total lead exposure was assessed during the environmental health response. Objectives of this investigation were to assess the influence of cultural/dietary habits on lead exposure pathways and estimate the contribution of contaminated food to children＇s blood lead levels（BLLs）. A survey of village dietary practices and staple food lead content was conducted to determine dietary composition, caloric intakes, and lead intake. Potential blood lead increments were estimated using bio-kinetic modeling techniques. Most dietary lead exposure was associated with contamination of staple cereal grains and legumes during post-harvest processing and preparation in contaminated homes. Average post-harvest and processed cereal grain lead levels were 0.32 mg/kg and 0.85 mg/kg dry weight, respectively. Age-specific food lead intake ranged from 7 to 78 μg/day. Lead ingestion and absorption were likely aggravated by the dusty environment, fasting between meals, and nutritional deficiencies. Contamination of staple cereal grains by highly bioavailable pulverized ores could account for as much as 11%–34% of children＇s BLLs during the epidemic, and were a continuing source after residential soil remediation until stored grain inventories were exhausted.