Sap flow in Searsia pendulina and Searsia lancea trees established on gold mining sites in central South Africa

Dye, P. J.; Naiken, Vivek; Clulow, Alistair D.; Prinsloo, Eric; Crichton, M. H. G.; Weiersbye, Isabel

doi:10.1016/j.sajb.2016.12.016

Cited by 6 publications

(5 citation statements)

References 19 publications

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“…lancea were planted in 2003 and 2004 together with other tree species in site-species phytoremediation trials on polluted groundwater from gold and uranium tailings dam at AngloGold Ashanti Limited’ West Wits and Vaal River mining operations in South Africa (“The Mine Woodlands Project”). , The biomass for this study was harvested from trees grown on deep, red well-draining soils (South African Hutton form) over polluted groundwater from the Mispah gold and uranium tailings dam, Vaal River mining operations, near Orkney, South Africa. The tree growth, impact on groundwater and soil, and biomass production are reported elsewhere. − , Four S. lancea trees were excavated and harvested at 12 years of age and divided into leaves, twigs, wood, dead wood, stump, root ball (coarse root), and roots (fine-medium root).…”

Section: Methodsmentioning

confidence: 99%

“…The tree growth, impact on groundwater and soil, and biomass production are reported elsewhere. [24][25][26][27]30 Four S. lancea trees were excavated and harvested at 12 years of age and divided into leaves, twigs, wood, dead wood, stump, root ball (coarse root), and roots (fine-medium root). The biomass was weighed, washed, and dried to ambient moisture content in a warehouse.…”

Section: Methodsmentioning

confidence: 99%

“…It is one of the species that is planted in phytoremediation woodlands for control of groundwater pollution from gold and uranium mine tailings dams in southern Africa , due to its ability to maintain transpiration rates in saline seepage and acid mine drainage . These traits in turn result in the hydraulic control of polluted groundwater , and the conversion of AMD to biomass . The woodlands are part of a mine closure strategy to control AMD from tailings storage facilities (TSF), and harvesting is only envisaged for the faster-growing trees.…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal Carbonization of Searsia lancea Trees Grown on Mine Drainage: Processing Variables and Product Composition

et al. 2021

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A 12-year-old planted woodlands Searsia lancea tree, grown on acid mine drainage for phytoremediation of polluted groundwater on gold and uranium mines in South Africa, was used in this research. The research describes the fuel-related characteristics and the influence of different operating conditions on the hydrothermal carbonization of the biomass and the combustion profiles of discard coal/biomass hydrochar pellets. The raw biomass was treated at temperatures ranging from 200−280 °C and residence time of 30−90 min. The hydrochar produced at 280 °C and residence time of 90 min had the highest calorific value of 29.71 MJ/kg compared to 17.23 and 16.73 MJ/kg obtained from the raw biomass and discard coal, respectively. Regression equations developed using the central composite design (CCD) indicated that the values obtained experimentally agree with the predicted values from the models for mass yield, calorific value, and ash content. The reactivity tests showed that the 100% hydrochar pellet had the highest reactivity and lowest ignition and burnout temperature compared to biocoal pellets and discard coal. The process water contained relatively low concentrations of major elements, and the study had shown that different high-grade biocoal pellets can be produced from the S. lancea tree.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrothermal Carbonization of Searsia lancea Trees Grown on Mine Drainage: Processing Variables and Product Composition

et al. 2021

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“…Shallow-rooted trees capable of establishment in rocky areas (where soil depth and volume limit commercial forestry species) are also required to intercept seepage and dry out the soil. Searsia lancea was selected based on its relatively high water-use and frost tolerance (Dye et al, 2017) and tolerance to rocky soils, mineimpacted water and contaminated mine soils. Being an indigenous species, it is more acceptable to regulators and the public than exotic options such as the Eucalyptus trees.…”

Section: Figure 3 Location and Distribution Of Evapotranspiration Tri...mentioning

confidence: 99%

Evapotranspiration to minimise acid mine decant from a decommissioned colliery

Haagner,

van Wyk

2023

Proceedings of the International Conference on Mine Closure

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Acidic mine water decant from legacy coal mines presents significant environmental impacts to the Highveld watercourses in South Africa. The costs and logistics for active treatment are often not feasible due to the remoteness of sites, excessive capital and operational costs, lack of infrastructure and complications with brine and sludge disposal. The regulatory authorities currently prefer active pumping and desalinating water from flooded underground compartments, followed by the discharge of treated water into natural watercourses. However, if a sufficient body of monitoring evidence can prove efficacy with a high degree of confidence, then lower-cost and more sustainable water management alternatives may become a reality.In this project we monitored different tree plantation trial blocks of two species that were established in 2012 to reduce vertical groundwater recharge from rainfall that would report to underground workings. Reducing the ingress rates to below critical levels would eliminate the decant of acidic mine water to receiving watercourses.Monitoring focussed on establishing water budgets (rainfall, throughfall, soil moisture and moisture extinction, sap flow and groundwater levels) via continuous logging instruments. The monitoring period was four years, from 2018 to 2022, once the trees were nearing maturity. The data were used in building a conceptual site model and then a geohydrological model to estimate draw-down within the trial blocks. A site survey for possible plantation expansion areas followed, after which the geohydrological model was again updated to extend the ingress reduction to a larger area.The study found that trees survived very well, but that different species were better suited to specific conditions. Water uptake and ingress reduction were very effective in all but the highest rainfall periods. The geohydrological model showed effective draw-down, with the expansion model confirming that the trees could limit vertical groundwater recharge to near zero. However, a residual interflow from deeper aquifers would still result in some recharge to underground workings. During periods of excessive rainfall, this would have to be pumped and used to irrigate plantations to prevent decant altogether.The establishment of commercial-scale forestry plantations with continuous-cover harvesting could fulfil an important role for local enterprise development, job creation and effective sustainable post-mining land-use, whilst contributing significantly to continuous passive groundwater decontamination, reducing groundwater liability and environmental degradation.

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“…Se ha desarrollado un polímero superabsorbente para las aguas provenientes de los relaves mineros. Este polímero es agregado al 1% en el relave, y desencadena la evaporación del agua separándola de los metales pesados (Dye et al, 2017). La minera "Witwatersrand Basin Goldenfields", es conocida por reutilizar sus relaves mineros en Africa del Sur, ocupando un área de 500 km 2 , evitando la contaminando del agua subterránea, superficial y de los sedimentos, al convertirlos en recursos ácidos (Ngole-Jeme & Fantke, 2017).…”

Section: Año 2017unclassified

Contaminación Del Agua Y Suelo Por Los Relaves Mineros

Menéndez

Muñoz

2021

Paideia XXI

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El presente documento tiene como objetivo discutir y analizar los efectos de la contaminación del agua y suelo producto de los residuos de relaves mineros. La actividad económica se basa principalmente en la explotación de los minerales, siendo exclusivos el oro y el uranio. En dichas actividades mineras es imposible la degradación de los desechos provenientes de los relaves, los mismos que contaminan los suelos, aguas superficiales, subterráneas y por ende en los ecosistemas tanto terrestres, como marinos y sus productos a consumir, como los peces y productos agrícolas, en detrimento de la salud de las poblaciones aledañas a las mineras. La presencia de elementos químicos y su alta toxicidad de sus componentes agrava su peligrosidad y su potencial como generador de impactos contaminantes en la salud de las personas y que sufran alteraciones altamente nocivas. Se revisaron 52 artículos arbitrados e indexados de las bases de datos Scopus y Scielo entre los años 2017 al 2020, los efectos de la contaminación del agua y suelo producto de los residuos de relaves mineros. Se concluye que los relaves mineros y el impacto medioambiental ante un proyecto de minería es inevitable, sobretodo en la degradación de los suelos, aguas superficiales, subterráneas y el aire. Esta contaminación provoca la presencia de elementos, minerales y metaloides, que originan perturbaciones en los modos de vida de las poblaciones humanas. Es necesaria la promulgación de las normas que puedan regular e impedir que la contaminación de los relaves siga afectando a la población y al medio ambiente. Finalmente esta revisión ha permitido percibir la necesidad de mayor información que si bien puede existir, existe una urgencia imperiosa del estudio sobre el impacto de contaminación de los relaves mineros sobre la salud humana y ecosistémica. Palabras clave: contaminación – medioambiente – minería – relaves

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Sap flow in Searsia pendulina and Searsia lancea trees established on gold mining sites in central South Africa

Cited by 6 publications

References 19 publications

Hydrothermal Carbonization of Searsia lancea Trees Grown on Mine Drainage: Processing Variables and Product Composition

Hydrothermal Carbonization of Searsia lancea Trees Grown on Mine Drainage: Processing Variables and Product Composition

Evapotranspiration to minimise acid mine decant from a decommissioned colliery

Contaminación Del Agua Y Suelo Por Los Relaves Mineros

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