remediation measurements

Transcription

1 IUNG Institute of Soil Science and Plant Cultivation PULAWY, POLAND International Workshop Current developments in remediation of contaminated lands Contamination by a pyrite mine spill in Spain: effect on soils and remediation measurements October 25 Francisco Martín Peinado Soil Science Department University of Granada. Spain.

2 Location (mm) Climate EFMAMJ JASOND 17.7ºC mean annual +1ºC in winter TERMIC and XERIC (USDA, 1999) (ºC) pp (mm) ETP (mm) Tª(ºC) 6 mm annual pp 9 mm annual ETP Soil use Agrio and Guadiamar river basins To the border of Doñana National Park (World Heritage by UNESCO in 1994) Crops Grazing Nat. Veg. Riverbed

3 MAIN MINERALS 2,1 5,4 1,4,9 7,1 83,1 Pyrite Sphalerite Galena Chalcopyrite Arsenopyrite Non productives FeS 2 ZnS PbS CuFeS 2 AsFeS EXTRACTED ELEMENTS: Zn, Pb, Cu, As Others: Cd, Tl, Sb, Ag, Bi, Cr, Hg, Ni

4 THE ACCIDENT Aznalcóllar s mine (Boliden-Apirsa) 25 th April hm 3 TAILINGS 4 hm 3 ACIDIC WATERS

5 km 5 m 4 km Tailings Thickness of tailings: > 1 m near the mine < 3 cm at the bottom Ton Ton Zn 16 Cu 4 Pb 16 Tl 1 58 km Acidic waters As 1 Cd 5

6 MAIN IMPACTS Total affected area: 42.9 km 2 4,2% Doñana Natural Park,2% Doñana National Park Loss of all crops (in and next to the area) Death of fauna (37,4 Ton fishes, 17 kg crayfishes, 96 vertebrate) 4 wells directly contaminated by tailing input Soils and waters contaminated by high concentrations of heavy metals and As

7 INITIAL CONTAMINATION Contamination in depth depended on the soil structure Dry soil (cracks) Good development High penetration Low development Low penetration

8 1 5,8 <2% <1% Loam 1% 15-2 MINE 5 8, >1% <1% Silty clay 1-2% >2 ENTREMUROS 2 5,9 <1% >35% Sandy loam <.5% <1 SANLÚCAR LA MAYOR AZNALCÁZAR 3 7,7 1% <1% Silty clay loam 1% ,8 5-1% <1% Loam 1% 1-15 SOIL PROPERTIES ph CaCO 3 Gravel Texture O.C. C.E.C. Soil types

9 INITIAL SITUATION Tailings saturated in water, reducing conditions, particle of sulphides remain stable SECONDARY CONTAMINATION Drying, tailing oxidation, releasing of contaminants

10 PYRITE OXIDATION O 2 H 2 O T. Thioox. FeS 2 Fe 3+ Pyrite (FeS 2 ) Sphalerite (ZnS) Chalcopyrite (CuFeS 2 ) Arsenopyrite (AsFeS 2 ) Galena (PbS) Bournonite (PbCuSbS 3 ) SO 4 2- H + Fe 2+ O 2 T. Ferroox. ph < 4,5 STRONG ACIDIFICATION RELEASING OF CONTAMINANTS Fe(OH) 3 H + ph > 4,5 Fe 3+ H 2 O SULPHATE FORMATION

11 4 May 2 May

12 Disolution and mobilization of contaminants (rainfalls)

13 Increasing of soil contamination

14 Aeolian contamination

15 1. Clean-up REMEDIATION MEASUREMENTS 5 trucks and 15 diggers 9 workers 2 days 6 hm 3 removed material 38% tailing 62% soil Material disposed of in the open cut mine

16 1. Clean-up In some areas more than 1.5 m soil were removed October May May

17 1. Clean-up Riverbed Before After

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19 Total contamination after the clean-up actions (mean values) 1 mg/kg UCS -5 cm -1 cm mg/kg Cd Tl 2 1 Cu Zn As Pb Area above intervention levels: 82% As; 4% Zn; 24% Pb. EC (ds m -1 ) Acidic soil Basic soil Percentiles 5 1 Percentiles

20 2.1. Liming Sugar-beet scum REMEDIATION MEASUREMENTS High CaCO 3 content (4%) Very fine particle size (reactive) High OM content (15-2%) Cheap (industrial waste) 4 kg m -2 acidic soils 2 kg m -2 neutral-alk. soils Tilling (25 3 cm) Dilution of the element concentrations in the uppermost 1 cm (after cleaning during 3 years and in the moderately contaminated areas)

21 EFFECT OF CLEAN-UP AND LIMING EVOLUTION OF SOIL PROPERTIES 1 8 Acidic soils 25 2 Basic soils % CaCO Percentiles Percentiles 1 8 Acidic soils Basic soils ph Percentiles Percentiles

22 Red soils and iron-rich material for As retention OM for retention of elements and recovery of the soils

23 REMEDIATION MEASUREMENTS 3. Phytoremediation Accumulator plants tested (de Haro, 1999) Mustards (Brassica juncea and Brassica Carinata) Pb Zn Cu Autochthonous plants collected in the area Amaranthus blitoides Pb, Cu, As Lavatera cretica Cd

24 Only exploratory level, strong limitations in the area Hard climatic conditions Heterogeneous and persistent contamination

25 AREA ABOVE INTERVENTION LEVELS IN 24 (Total concentrations) Intervention levels (agricultural soils) (mg/kg) (13%) Zn (39%) (68%) As (82%) ph<7 ph>7 Cu 3 5 Zn 6 1 Cd 7 1 (7%) Pb As 5 5 (24%) Pb 35 5 Tl 5 5 Cu, Cd and Tl = % Uncontaminated soil

26 ,5,4,3,2,1 3,5 3 2,5 2 1,5 1,5 SOLUBLE (in water) concentrations All soils Pbw 98 Pbw 99 Pbw 1 Pbw 4 All soils 2% Asw 98 Asw 99 Asw 1 Asw 4,7,6,5,4,3,2,1 % Intervention levels (mg/kg) Cu Zn Cd As Pb Tl All soils,7,5,3, ,1 5% Tlw 98 Tlw 99 Tlw 1 Tlw 4

27 SOLUBLE (in water) concentrations Acidic Acidic Znw 98 5% 22% Cuw 98 Znw 99 Cuw 99 Znw 1 Cuw Znw 4 Basic 3 2,5 2 1,5 1,5 Basic Cuw % 1% Cd = Cu

28 EDTA extracted concentrations All soils ZnE 98 ZnE 99 ZnE 1 ZnE All soils CuE 98 CuE 99 CuE 1 CuE All soils AsE 98 AsE 99 AsE 1 AsE All soils CdE 98 CdE 99 CdE 1 CdE ,5,4,3,2,1 All soils TlE 98 TlE 99 TlE 1 TlE All soils PbE 98 PbE 99 PbE 1 PbE 4

29 What would happened if the tailings were not removed? Weathering layer (4 days) 6 years 12 mm Tailing 3 years 4 years 6 years cm Pale greyish layer 8 cm 15 cm 7 cm 4 cm Reddish layer 4 cm Unaffected soil

30 Strong degradation of the soil properties g/kg cmol c kg days 6 years % Depth (mm) ph CaCO C.E.C. Calcium carbonate dissolution produced a gypsum precipitation 6 O.M. Fe SO H + + 4CaCO 3 + 8H 2 O Fe CaSO 4 2H 2 O + 4CO 2 + 4OH %

31 Partial dissolution of silicates (phylosilicates, feldspars) Fe 3+ + Al SO H + + 4CaCO 3 + 5H 2 O Fe(OH) 3 + Al(OH) 3 + 4CaSO 4 2H 2 O + 4CO 2 K.6 Mg.25 Al 2.3 Si 3.5 O 1 (OH) 2 + 8H + + 2H 2 O.6K Mg Al H 4 SiO 4

32 Plumbojarosite [PbFe 6 (SO 4 ) 2 (OH) 12 ] Neoformation of new minerals Jarosite [KFe 3 SO 4 (OH) 6 ] Ferrihydrite [5Fe 2 O 3 9H 2 O] Schwertmannite [Fe 8 O 8 (OH) 6 SO 4 ]

33 Heavy metals and As Pb t (mg/kg) As w mg/kg Depth (mm) Depth (mm) years 4 years 6 years As t mg/kg 3 years 4 years 6 years Depth (mm)

34 3 years Heavy metals and As Zn (mg/kg) years Zn (mg/kg) Depth (mm) Zn w Zn t Depth (mm) = Cd and Cu

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39 The remediation actions minimized the impact of the spill, but the soils have definitely lost their agricultural use 162,5, 63,, zlotych GUADIAMAR GREEN CORRIDOR Supervision and monitoring of the pollution Ecological restoration Soils, geomorfology, hidrology, botany and zoology Alternative development (natural and human systems)

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44 Thanks for your attention