Tree species as assets for mine phytoremediation

Transcription

1 Tree species as assets for mine phytoremediation N.S. Mokgalaka-Matlala, T. Regnier, S. Combrinck Department of Chemistry, Tshwane University of Technology, South Africa I.M. Weiersbye School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, South Africa AP & ES

2 Mine Closure Planning Codes of good practice Mining companies must adopt sustainable development principles Closure planning is ideally initiated at the earliest stages of development of a mine Post-mining land use

3 Mine remediation Mine remediation activities require a combination of technologies Physical Chemical Biological Plants used to stabilise, extract and degrade contaminants Development of resilient vegetation depends on the use of tolerant plant species

4 AngloGold Ashanti, Ltd Mine Woodland Trial (2001 to 2007) Approx. half a million acid and salt-tolerant trees and shrubs have been planted Trials on polluted ground water, soil, slimes dam and landfill Indigenous woody tree species

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6 Experimental sites Sampling Area Site Soil Type Contamination Level Vaal River Mine Moab Khotsong Sand and rock High West Wits Red Soil Mponeng Sand High West Wits Shallow Soil TauTona Sand Medium Pretoria Sand None Johannesburg Sand None

7 Plot layout Westwits red soil 63 trees planted in a 9 x 7 grid individual trees are 2.5 m away from the adjacent tree and 3.0 m away from the trees in the next row

8 A B C D Sampling sites (A and B) Vaal River Mine, (C and D) West Wits operations (Shallow Soil and Red Soil)

9 Post-mining land use 23.5% Unemployment in South Africa (May 2009, Stats SA) 50% (24 million) people live below the poverty line of R354 per month (1 US$ = R6.89 November 2010) Since 2002 community-based nurseries produces suitable ecotypes to sell to AGA and other mines Other ventures include production of safe indigenous plant products

10 Small community-based industries Thatch Fibres Essential oils Polyphenolics Natural dyes Fuel wood Fixatives (resins/gum) Precious wood

11 Plant species suitable for postclosure land use and communitybased industries

12 Family: Anacardiaceae Rhus The genus Rhus consists of about 200 species distributed over the tropical and subtropical parts of the world. Approximately 111 species found in southern Africa, some with medicinal properties. The sap of Rhus chirindensis is used in traditional medicine for treating heart complaints. The bark is also used to strengthen the body, to stimulate blood circulation and in the treatment of rheumatism and mental disorders.

13 Rhus lancea (Swartkaree) Small to medium sized evergreen tree Hardy, evergreen, drought and frost resistant Bark used for tanning Limited information concerning the secondary metabolites produced by R. lancea

14 Rhus pendulina (Witkaree) Small to medium sized evergreen tree Hardy, evergreen, drought and frost resistant An infusion of leaves in milk used in children suffering from stomach upsets

15 Using chemometrics to characterize specimens growing on mine contaminated sites

16 Chemometrics Chemometric modeling allows a simplified Principal overview Component of complex Analysis data, to (PCA) highlight Partial similarities Least Squares and differences (PLS) between groups of Allows used observations, to identification accomplish to show regression of those up variables trends modeling and that between indicate provide two sudden blocks shifts of data, in of data which one block represents a unique information about the observations or contribute response variable similar information to the model makes it possible to determine how various observations influence the responses obtained and how the responses correlate with one another

17 Near infrared spectroscopy Measurement of the wavelength and intensity of the absorption of near-infrared light by a sample NIR radiation (800 nm to 2500 nm) is energetic enough to excite molecular vibrations to higher energy levels Used for quantitative measurement of organic functional groups, especially O-H, N-H, and C=O

18 Near Infrared spectroscopy Green tool used for characterisation of the chemical nature of the matrix in the absence of undesirable solvent extraction methods that yield chemical waste

19 R 2 Secondary metabolites R 1 O Provide protection against insect predators and microbial pathogens Phenolics and tannins exhibit antioxidative activities and are used in pharmacological applications Phenolic compound mixtures are often antimicrobial agents and are known to improve the antioxidant status of plasma in humans Flavonoids are used to treat human ailments (prevent development of cancer and heart diseases) R O

20 Phenolic Compounds Plant-based materials (phytochemicals) External stimuli such as microbial infections, ultraviolet radiation, and chemical stressors induce their synthesis

21 Total soluble phenolics in R. lancea A B C (A) Natural population; (B) Vaal river mine; (C) West Wits mine

22 Non-conjugated Phenolics in R. lancea (A) Natural population; (B) Vaal river mine; (C) West Wits mine

23 µg tannic acid/g DW Soluble tannins in R. lancea A B C (A) Natural population; (B) Vaal river mine; (C) West Wits mine

24 Rhus lancea Mine populations (blue and green) vs natural populations (red) FEB

25 Rhus lancea Mine populations (blue and green) vs natural populations (red) FEB

26 Rhus lancea Vaalriver mine (blue) vs natural populations (red)

27 Rhus lancea Westwits(blue) vs natural populations (red)

28 Rhus pendulina seasonal variation Rhus pendulina seasonal variation

29 Rhus pendulina Westwits shallow soil (blue), Westwits red soil (green), Vaal river mine (red) FEB

30 Rhus pendulina Westwits shallow soil (blue), Westwits red soil (green), Vaal river mine (red) MAY

31 Rhus pendulina Westwits shallow soil (blue), Westwits red soil (green), Vaal river mine (red) NOV

32 Rhus pendulina Mine populations vs natural populations FEB

33 Rhus pendulina Mine populations vs natural populations FEB

34 Bioactive, commercially valuable phenolic compounds in Combretum erythrophyllum

35 Combretum erythrophyllum Traditionally used to treat diseases including: - internal (chest coughs, abdominal pain and venereal diseases) - external infections (wounds)

36 mau mau DAD1 A, Sig=280,8 Ref=360,50 (CHARLY\AFCDELAY \ D) DAD1 B, Sig=320,8 Ref=420,50 5 (CHARLY\AFCDELAY \ D) nm 320 nm min High performance liquid chromatograms of a methanolic leaf extract of Combretum erythrophyllum grown on acid mine drainage Peaks 1, 2 and 3 Flavonoids and hydroxybenzoic acids (absorption max at 280 nm) DAD1 C, Sig=380,8 Ref=420,50 5 (CHARLY\AFCDELAY \ D) mau nm min Peaks 4 and 5 Hydroxycinnamic acids (absorption max at 320 nm, absent at 280 nm) 100 0

37 PLS scores plot Loadings plot B JHB PTA VRM WWRS WWSS PEAK1 PEAK2 PEAK3 PEAK4 PEAK5

38 PCA scores plot of the variation of the five major compounds present in leaf extracts of Combretum erythrophyllum from different plots over the growing season February B May November Peak 1 Peak 2 Peak 3 Peak 4 Peak 5

39 Separation and identification of phenolic compounds using HPLC 5: apigenin 6: kaempferol 8: genkwanin Purified Combretum erythrophyllum leaf extract

40 Apigenin, kaempferol and genkwanin have excellent FEB MAY antimicrobial properties NOV Extracts containing these compounds could find application in antimicrobial preparations and perhaps present opportunities for the development of a commercial product Loadings plot for the production of apigenin, kaempferol and genkwanin by Combretum erythrophyllum growing in mine sites during different seasons

41 Use of Lippia scaberrima essential oil in the postharvest management of subtropical fruits

42 Lippia scaberrima One of four indigenous Lippia species in South Africa Occurs mainly in Gauteng, North West and Free State Provinces Aromatic shrub known as Beukesbossie Perennial with woody stems and deciduous leaves Medicinal plant used to treats coughs, colds, fever and digestive disorders Large root system and reaches a height of 0.3 to 0.6 m

43 % Essential oil profiles of Lippia scaberrima Sond. from Highveld gold and uranium mines Limonene R-carvone NP1 NP2 WWLC WW MC WW HC VR LC1 VR LC2 VR LC3 VR HC Sampling sites Feb 2008

44 Application of Lippia essential oil Incorporated into agar medium Tested for ability to inhibit in vitro growth of Colletotrichum gloeosporioides and Botryosphaeria parva

45 In vivo testing of the essential oil Carnauba coating + fungicide Mangoshine coating + fungicide Carnauba based + oil Mangoshine coating + oil

46 In vivo testing of the essential oil

47 Conclusion Several factors must be considered if plants growing on contaminated soils are to be used as a source of useful secondary metabolites These include the effect of soil contamination on the levels of the metabolites of interest, the timing of harvest, the metals contents of the leaves used to prepare extracts and the biological activities of such extracts

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