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Amparo Cortes - Sustainable remediation of soils and groundwaters affected by chlorinated solvents
- 1. VII Jornadas Técnicasde Medio Ambiente Problemática de los suelos contaminados SUSTAINABLE REMEDIATION OF SOILS AND GROUNDWATERS AFFECTED BY CHLORINATED SOLVENTS by Dra. Amparo Cortés Full Professor at Universitat de Barcelona acortes@ub.edu 16 – 17 de Noviembre 2011, Barcelona
- 2. SUSTAINABLE REMEDIATION OFSOILS AND GROUNDWATERS AFFECTED BY CHLORINATED SOLVENTS INDEX 1. Chlorinated solvents: positive and negative properties 2. Release to the environment: environmental problems 3. Containment technologies 4. Treatment technologies 5. New trends in characterization 6. Some reflections
- 3. CHLORINATED SOLVENTS TCA CT CF
- 4. CHLORINATED SOLVENTS WIDESPREAD USES Industry Industrial processes Electronics manufacturing Metal cleaning Solvent production Metal machining Pesticide / herbicide manuf. Die operations cutting, bending, forming, drawing and squeezing Dry cleaning Vapour and liquid degreasing Instrument manufacturing Paint stripping Solvent recycling Storage and transfer of solvents Engine manufacturing Steel product manufacturing Chemical production Rocket engine / fuel manufacturing Aircraft cleaning / engine degreasing
- 5. ATTRIBUTES, and INDUSTRIALVALUES OF CHLORINATED SOLVENTS Source: DDES, 2008
- 6. CHLORINATED SOLVENTS HUMANTOXICITY CHLORINATED ETHENES PCE Tetrachloroethylene causes irritation of the upper respiratory tract and eyes, kidney dysfunction, and at lower concentrations, neurological effects, such as reversible mood and behavioral changes, impairment of coordination, dizziness, headache, sleepiness, and unconsciousness. TCE/ Trichloroethylene: Short-term exposure causes irritation of the nose and throat and central nervous system (CNS) depression, with symptoms such as drowsiness, TRI dizziness, giddiness, headache, loss of coordination. High concentrations have caused numbness and facial pain, reduced eyesight, unconsciousness, irregular heartbeat and death. Vinyl Chloride: Aside from being a known carcinogen, it has been found to cause a VC number of other conditions, including Raynaud's syndrome, angiosarcoma, and acroosteolysis.
- 7. CHLORINATED SOLVENTS HUMANTOXICITY CHLORINATED METHANES CT Carbon tetrachloride is listed as a suspect carcinogen, an animal carcinogen at relatively high doses, not a likely human carcinogen; however, liver cancer has been reported. It can be absorbed through intact skin. It causes CNS depression, can damage the kidneys, liver, or lungs, and can cause anemia, rapid and irregular heartbeats. Health effects appear to be greatly increased by alcohol consumption. CF Chloroform is a suspect carcinogen. It causes CNS depression, rapid and irregular heartbeat, and liver and kidney damage. DCM Methylene chloride is listed as a potential carcinogen. It causes CNS depression, liver and kidney damage, and can cause elevated blood carboxyhemoglobin.
- 8. ENVIRONMENTAL CHALLENGES OFCHLORINATED SOLVENTS Source: DDES, 2008 1 L of TCE can theoretically contaminate 190,000 cubic meters of water with TCE at a concentration above the drinking water standard.
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- 10. CHLORINATED SOLVENTS RELEASEDAT THE ENVIRONMENT: PRODUCTION AREAS
- 11. CHLORINATED SOLVENTS RELEASEDAT THE ENVIRONMENT: END POINTS
- 12. CHLORINATED SOLVENTS ENVIRONMENTALDISTRIBUTION halos source
- 13. SOURCE ZONE A chlorinatedsolvent source zone is a subsurface reservoir that: a) initially contains DNAPL and b) sustains plumes (including vapor plumes). The source zone also includes high concentration dissolved- and sorbed-phase halos around the DNAPL region. Some chlorinated source zones are depleted of DNAPL; than the high-concentration halo can be a reservoir that sustains plumes.
- 14. DENSE NON-AQUEOUS PHASELIQUIDS DNAPL include chlorinated solvents Immiscibility with water - they form separate ‘phases’. Low absolute solubilities - DNAPL can’t dissolve quickly in groundwater: it may persist for decades before dissolving. Relatively high densities - DNAPLs are denser than water, and can therefore sink beneath the water table, polluting the full thickness of an aquifer. Low viscosities – that allows rapid subsurface migration.
- 15. DNAPL MASS REDUCTION Pumpand treat in the source Initially Later
- 16. POTENTIAL NEGATIVE IMPACTSOF DNAPL MASS REDUCTION Pump and treat • Expansion of the source zone due to mobilization of residual DNAPL • Undesirable changes in the DNAPL distribution • Undesirable changes in physical, geochemical, and microbial conditions • Adverse impact on subsequent remediation technologies • Increased life-cycle costs of site cleanup.
- 17. CONTAINMENT TECHNOLOGIES Source: DDES, 2008
- 18. SCREENING OF CONTAMINANTS and AGING OF CONTAMINATION • Phytoscreening focuses on the youngest tree rings (sap uptake of contaminants) and reflects the current state of contamination in the root zone. It can be used for mapping certain contaminants. • Dendrochemistry focuses on the annual rings of the tree (xylem) which reflect the changes (contamination) in the root zone. It can be used for age dating of contamination (forensic, source identification).
- 19. Phytoscreening Soil and groundwatercontaminants are uptaken and transported by sap in the outermost wood rings. These can easily be micro-sampled (0.2 g) and analyzed for the sap enriched contaminants. This method allows to qualitatively and quantitatively identify or exclude the presence of underground contaminants such as PCE, TCE, DCE … The correlation coefficient between tree and underground contamination is respectable (and up to 0.9). Whenever a site is properly vegetated, Phytoscreening can be used for a rapid identification or exclusion of contamination, for clarifying contaminant distribution by fast low cost measurements, for identification of release spots and delineation or monitoring of plumes. Being a standard method for CVOCs, BTEX and heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) we will see in the next future, if this method is also suitable for PAH, PCB and other organic compounds.
- 20. Burken et al.,2011
- 21. Dendrochemical Age-Dating Due totheir seasonal growth, annual tree-rings represent a bio-archive of the past. During this growth process elements taken up with the sap from the rhizosphere are being built in and fixed to wood cells. Accordingly and besides heavy metals pollutant specific tracer elements such as Chlorine (for chlorinated organic compounds like PCE) or Chlorine and Sulfur (for Fuel Hydrocarbons) are built in and fixed to the wood cells. This growth related element incorporation exclusively takes place within the youngest annual ring with the resulting element concentration depending on the respective element availability in soil and groundwater. The change in concentration over all annual rings of a tree core sample from the stem can be gained for 30 elements with the help of energy-dispersive X-Ray-analysis (ED-XRF).
- 22. Dendrochemical Age-Dating This processdelivers the concentration profiles of 30 elements over the total life time of a tree can be obtained at a very high temporal resolution. Accordingly, concentration anomalies of pollutant specific elements (tracers such as Chlorine) can be dated exactly to reveal the beginning and duration of an underground impact (such as by PCE). In order to rule out or confirm the possibility of alternative sources for the Chlorine anomalies (e.g. road salt), allied element concentration profiles (e.g. K, Ca, Mg, S) are compared for Cl-synchronous anomalies (multi-element-analyses). If more trees are available the spatiotemporal expansion of a plume as well as contaminant transport velocities can be revealed.
- 23. IN SITU SOURCETREATMENT TECHNOLOGIES Source: DDES, 2008
- 24. ABIOTIC AND BIOTICTRANSFORMATIONS
- 25. ANAEROBIC REDUCTIVE DEHALOGENATION PCE Cl Cl C C Cl Cl TCE Cl Cl C C Cl H 1,1-DCE cis - 1, 2-DCE trans-1, 2-DCE Cl H Cl Cl H Cl C C C C C C Cl H H H Cl H Vinyl Chloride H Cl C C H H Ethene Complete Mineralization H H O O O Cl C C C H H H H Ethane H H C C H H H
- 26. BIODEGRADATION EVALUATION Isotope analysisis a powerful tool to evaluate natural and/or enhanced biodegradation of different contaminants. Isotopes can also be used to conceptualize your site models (e.g. flow paths, degradation pathways) and to identify additional sources of contamination. Carmona et al., 2011
- 27. SUSTAINABLE REMEDIATION Ability ofa system to maintain important attenuation mechanisms through time. Sustainability is affected by the rate at which the contaminants are transferred from the source area and whether the protecting mechanisms are renewable. In the case of reductive dechlorination, sustainability might be limited by the amount of electron donor, which might be used up before remedial goals are achieved. A competition for electrons is established during degradation between chlorinated solvents, other organic pollutants, organic matter, and other electron acceptors that can be present at the media such as nitrates and sulphates.
- 28. REDUCTIVE DECHLORINATION SUSTAINABILITY Chlorinatedsolvents and other organic pollutants may also act as electron donors providing an energy source for certain microorganisms. With the continual exchange of electrons, redox chemistry is an important factor in chlorinated solvents biodegradation. PCE, TCE, and CT generally require reducing conditions before they will transform to aliphatic compounds. Such conditions require the presence of enough organic substrate to reduce all of the oxygen (below 0,5 mg/L), nitrate (below 1 mg/L ideally), iron, and sulfate ideally (below 20 mg/L) before dechlorinating bacteria will successfully compete to reduce chlorinated aliphatic hydrocarbons.
- 29. At site Bnitrate levels are low, but still reach bad levels for reductive dechlorination. A previous water nitrate reduction treatment is needed in the site.
- 30. The biodegradation ofchlorinated solvents in soils, at low concentrations can be enhanced by using adapted mycorrhized trees producing phenolic exudates, but such biodegradation could be also affected by the ionic strength of nitrates or other salts when present. Plants will also contribute to the soil remediation via chlorinated solvent uptake and dechlorination in plant systems.
- 31. ASSESSMENT of MASSDISCHARGE FROM DNAPL ZONES • Plane versus point measurements. • Multi level sampling methods needed in a control plane. • Main parameter influencing mass discharge calculations: Hydraulic conductivity . • Effective number of sampling wells related to the value of the mass discharge (good point for optimization to save money and time). • Uncertainty analysis of mass discharge.
- 32. Carmona et al.,2011
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- 35. D R+ WORKING GROUP GEA Grup R+D de Geologia Econòmica i Ambiental Dra. Amparo Cortés (UB-Farmàcia) i Hidrologia Dr. José Mª Carmona (UB-Geologia) Dra. Diana Puigserver (UB-Geologia) Dra. Magdalena Grifoll (UB-Biologia) Dr. Manel Viladevall (UB-Geologia) GROUP OBJECTIVES • Improving knowledge on medias, and on health and environmental risks; • Reducing costs of sustainable soils and ground waters remediation, while increasing efficiency and preventing health risks.