Restoration of contaminated Elbe River floodplain soils by phytoremediation R. Meissner, S. Bolze, H. Rupp- Helmholtz Centre for Environmental Research - UFZ C. Baum, D. Zimmer, P. Leinweber University of Rostock M. Grau, U.Klee, F. Tetzlaff, P. Pickel University of Halle-Wittenberg
Topics - Introduction - Status quo of floodplain contamination - Research strategy - Preliminary results and discussion -- Plant uptake of contaminants -- Hydrological regime and behaviour of contaminants -- Using the biomass for the production of energy - Conclusions - Acknowledgement Page 2
Hamburg Berlin Magdeburg Elbe Elbe River catchment area 148 268 km 2 Germany: 97 175 km 2 Labe Rhein Page 3
Page 4 Flood damages in Germany, August 2002
Industrial pollutants Municipial and agricultural pollutants Sediments in a floodplain of the Elbe River after a flood event (floodplain area: about 80.000 ha) Page 5
Sketch of a floodplain at the Elbe River relic floodplain dike agricultural use recent floodplain succession Page 6 Foto: R. Schwartz groyne-field Elbe River
Transport of pollutants in a floodplain BBodSchV aah Page 7 am BBodSchV: German soil protection act (1999), differs in: Precaution Examining Action values
Contamination of top-soils in floodplains of the river Elbe with As and significant heavy metals (until Aug. 2002) As Cd Cr Cu Hg Ni Pb Zn Amount 122 199 202 205 184 189 205 205 (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) Minimum 3 0.1 10 8.8 0.2 7 11 34 10% 20 0.8 32 26 1 18 42 135 25% 31 1.6 52 54 1.7 27 74 264 Median 50 3.1 82 96 3.5 38 110 482 Average 64 4.4 98 117 5.6 41 126 585 75% 91 5.7 126 156 8 48 160 749 90% 130 9.4 185 252 13 65 224 1273 Maximum 200 30 355 540 31 140 370 2500 Grassland Action value 50 20 1300; 200 for Sheep 2 1900 1200 The action value of the BBodSchV for As, Cu, und Hg are frequently exceeded (for Hg > 70 per cent of all investigated sites). Page 8
Contamination of grassland vegetation in floodplains of the river Elbe with As and significant heavy metals (until 2002) As Cd Cr Cu Hg Ni Pb Zn Amount 102 133 66 68 118 45 134 67 (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) Minimum 0.01 0.04 0.2 0.8 0.01 1.1 0.06 22 10% 0.1 0.1 0.7 9 0.01 2 0.25 46 25% 0.2 0.2 1.5 11 0.02 2.2 0.3 70. Median 0.3 0.4 2.6 13.4 0.03 3 0.5 109 Average 0.5 0.5 3.7 13.8 0.15 3.9 1.30 134 75% 0.6 0.6 3.8 16 0.1 4.2 1.23 136 90% 1 0.9 5.6 20 0.6 6.6 3 180 Maximum 5.7 3 30 27 1.6 13.5 18.2 705 Maximum value acc.to Animal Feed Reg. 2 1 0.1 40 Contamination values of grassland vegetation do not reflect the soil contamination Page 9
Summary status quo of floodplain contamination and research goals Floodplains retention areas for floods and sediments Sediments loaded with pollutants (i.e. heavy metals and As, organic pollutants) due to anthropogenic activities Contamination hot spots (bayou hollows in the floodplain exceeding of limits and precaution values of BBodSchV) Highly dynamic hydrological regime - the behavior of heavy metals, As, and organic pollutants regarding mobilization, immobilization, plant uptake etc. is unknown Main research question: Is it possible to restore the contaminated floodplain soils by phytoremediation and can we use the biomass to produce energy? Page 10
Research strategy of the phytoremediation project - promoted by the German duration: 04/2007 until 03/2010 Phytoremediation of contaminated floodplain soils Sub-project 1 Bio-technology of phytoremediation & special analytics (Univ. Rostock) Sub-project 2 Hydrology of floodplain sites & mechanisms of heavy metal release (UFZ- coordinator) Sub-project 3 Process engineering of thermal utilization & economic fundamentals (Univ. of Halle) Page 11
Step 1: Biotechnology Increased biomass Stimulating the uptake of heavy metals by willows and poplars by selection and inoculation with siteadapted Ectomycorrhiza fungi... and higher metal concentrations 500 mg Zn kg -1 800 mg Zn kg -1 Ectomycorrhiza Pot experiments with floodplain soils and Salix x dasyclados (willow species) without (Ctr) and with inoculation with two species of Ectomycorrhiza-fungi (GÜL, FRA) Page 12
Essential results of a pot experiment with dual inoculated willows (fungi and bacteria) in comparison to a non-inoculated control - Total Cd and Zn accumulation increased up to 62 % due to higher biomass production in the inoculated willows - Decrease of theoretical remediation time for Cd and Zn from 70 (control) to 45 years Page 13
Step 2: Design of an experimental field trial in the Elbe River floodplain near Schoenberg Hamburg Elbe Berlin Data logger Vacuum system for suction cups Field site Schönberg Deich (ELBE km 435) Rhein Labe Willows control vs. inoculated Reference gauge 20 40 60 Suction cups GWgauge FDR 60 40 20 PT 100 60/1 40/1 20/1 20/5 40/5 60/5 Redox probes 3 m Poplars 20 40 60 Tensiometer control vs. inoculated In situ remediation site 16 m Field plot Page 14
Results of the in situ experiments Changing of the As concentrations in pore water at the three depths during inundation periods 16 14 As15 As45 As85 ElbeGauge 800 700 As [µg/l] 12 10 8 6 4 2 0 01.01.2005 01.07.2005 01.01.2006 01.07.2006 01.01.2007 01.07.2007 Date 600 500 400 300 200 100 Water level [cm asl.] As partly exceeded the precaution value for the path soil groundwater (BBodSchV, 1999) Page 15
Results of the in situ experiments Changing of the Zn- concentrations in pore water at three depths during inundation periods Zn [µg L -1 ] 1400 1200 1000 800 600 400 200 Zn15 Zn45 Zn85 Elbe 800 700 600 500 400 300 200 Elbe River Gauge [cm asl.] Zn partly exceeded the precaution value for the path soil groundwater (BBodSchV, 1999) 0 100 01.01.2005 01.07.2005 01.01.2006 01.07.2006 01.01.2007 01.07.2007 Date Page 16
Lysimeter experiments Populus/ Salix 0,7 m 0,1 m 0,2 m Soil monolith Probes (soil moisture, redox, temperature) GW-Level variation, flooding / 0.2 m / 0.4 m Device for GW-level regulation and reference probe for redox measurement - soil monoliths, diameter 0.3 m, depth 0.9 m 0,3 m - cont. measurement of soil moisture, redox, temperature - suction cups, seepage sampling - e.g. HM-analysis - variation of GW-level - drying and rewetting cycles - soil acidification Page 17
Results of the lysimeter experiments Redox and As- concentration in a depth of 10 cm and GW-level inside the lysimeter same behavior as monitored in situ 10 700 20 600 As [µg*l -1 ] 8 6 Eh [mv] 500 400 300 200 Eh GW-Level As 25 30 35 GW-Level [cm b.s.] 4 100 40 0 26.05.2009 09.06.2009 23.06.2009 07.07.2009 21.07.2009 04.08.2009 Date Page 18 26.05.2009 02.06.2009 09.06.2009 16.06.2009 23.06.2009 30.06.2009 07.07.2009 14.07.2009 21.07.2009 28.07.2009 04.08.2009 11.08.2009
Results of the lysimeter experiments Redox and Zn- concentration in a depth of 10 cm and GW-level inside the lysimeter same behavior as monitored in situ 500 700 20 600 Zn [µg L -1 ] 400 300 Eh [mv] 500 400 300 200 Eh GW-Level Zn 25 30 35 GW-Level [cm b.s.] 100 40 200 0 26 Mai 9 Jun 23 Jun 7 Jul 21 Jul 4 Aug 2009 Page 19
Preliminary results of the in-situ field experiment Heavy metal per m 2 Cd Cu Ni Pb Zn HM mass (mg ) for removal from soil 740 21249 0 14795 73633 HM mass (mg) input with sediment 0.84 12.4 11 27.8 142 Dual inoculated willows annual HM removal by willow shoots (mg) 4 2 2 0.12 170 years for remediation 242 - - - 2598 Non inoculated willows annual HM removal by willow shoots (mg) 2 1 1 0.07 96 years for remediation 546 - - - - HM Heavy metals Depth of soil: 0.1 m Flood channel: loamy to clay texture, ph < 6 Page 20
Step 3: Production of bioenergy Page 21
Page 22 Teaching-, research- and demonstration pilot plant at the Martin-Luther-University of Halle-Wittenberg System for the usage of bio energy
Harvest and preparation of the contaminated wooden material before thermo-chemical gasification Harvesting the willow resp. poplar plantation in the floodplain with a self-propelled harvester Humidity of the wooden material after harvest: >50%; shredding to a chip size of about 30x30mm (G30) Technical drying of the chips to a moisture content of approximately 35% (optimum for gasification process) with hot air from the gasification facility Page 23
Flow chart of energy during the thermo-chemical gasification process K. Purr, adapted: M. Grau 194 kw input power of biomass (40 kg wooden material per h = 4,9 kwh/kg) and production of a fuel gas with an energy content of about 144 kw bound in chemical compounds (CO, H2, CH4 and other gaseous hydrocarbons) cold gas efficiency = 74% Page 24
Conclusions Phytoremediation of contaminated floodplain soils is possible, but needs a lot of time it is better to call it phytomanagement Inoculation with ectomycorrhizal fungi improved the amount of heavy metal transfer from soil to plant; in floodplains willows are more suitable than poplars The field investigations showed that due to inundation an appreciable mobilization resp. immobilization of heavy metals and As occurred The sustainable use of contaminated wood for the production of energy seems to be possible Further research is necessary to explain the mechanisms of heavy metal transfer into the inoculated willows during flooding events, to develop site adapted strategies to increase the uptake of pollutants and to calculate the economic benefits of this remediation measure Page 25
Thanks for your attention and the for funding the project! Restoration of contaminated Elbe River floodplain soils by phytoremediation Contact: ralph.meissner@ufz.de