- 1. Problemtica de los suelos contaminados SUSTAINABLE
REMEDIATION OF SOILS AND GROUNDWATERS AFFECTED BY CHLORINATED
SOLVENTS by Dra. Amparo Corts Full Professor at Universitat de
Barcelona [email protected] 16 17 de Noviembre 2011, Barcelona VII
Jornadas Tcnicas de Medio Ambiente
2. SUSTAINABLE REMEDIATION OF SOILS AND GROUNDWATERS AFFECTED BY
CHLORINATED SOLVENTS 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 INDEX 3. CHLORINATED SOLVENTS
TCATCA CFCF CTCT 4. 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
CHLORINATED SOLVENTS WIDESPREAD USES 5. ATTRIBUTES, and INDUSTRIAL
VALUES OF CHLORINATED SOLVENTS Source: DDES, 2008 6. CHLORINATED
ETHENES 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. Trichloroethylene:
Short-term exposure causes irritation of the nose and throat and
central nervous system (CNS) depression, with symptoms such as
drowsiness, 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 number of other conditions, including Raynaud's syndrome,
angiosarcoma, and acroosteolysis. CHLORINATED SOLVENTS HUMAN
TOXICITY PCE TCE/ TRI VC 7. CHLORINATED METHANES 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. Chloroform is a suspect carcinogen. It causes
CNS depression, rapid and irregular heartbeat, and liver and kidney
damage. Methylene chloride is listed as a potential carcinogen. It
causes CNS depression, liver and kidney damage, and can cause
elevated blood carboxyhemoglobin. CHLORINATED SOLVENTS HUMAN
TOXICITY CT CF DCM 8. ENVIRONMENTAL CHALLENGES OF CHLORINATED
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. 9.
http://www.eurochlor.org/upload/documents/document436.pdf 10.
CHLORINATED SOLVENTS RELEASED AT THE ENVIRONMENT: PRODUCTION AREAS
11. CHLORINATED SOLVENTS RELEASED AT THE ENVIRONMENT: END POINTS
12. CHLORINATED SOLVENTS ENVIRONMENTAL DISTRIBUTION sourcehalos 13.
A chlorinated solvent 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.
SOURCE ZONE 14. DENSE NON-AQUEOUS PHASE LIQUIDS DNAPL include
chlorinated solvents Immiscibility with water - they form separate
phases. Low absolute solubilities - DNAPL cant 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 Pump and treat in
the source Initially Later 16. POTENTIAL NEGATIVE IMPACTS OF 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 groundwater contaminants 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 to their 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 process delivers 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
SOURCE TREATMENT TECHNOLOGIES Source: DDES, 2008 24. ABIOTIC AND
BIOTIC TRANSFORMATIONS 25. ANAEROBIC REDUCTIVE DEHALOGENATION C l C
l C l C l C C C l C l C l C C H TCE PCE trans- -1, 2 DCE C l C l C
C H H cis - 1, 2-DCE C l C l C C H H 1,1-DCE C l C l C C H H Ethene
C C H H H H Ethane C C H H H H H Vinyl Chloride Complete
Mineralization C l C H H H C C l OO O HHC 26. Isotope analysis is 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. BIODEGRADATION
EVALUATION Carmona et al., 2011 27. Ability of a 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. SUSTAINABLE REMEDIATION
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. Chlorinated solvents 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. REDUCTIVE DECHLORINATION
SUSTAINABILITY 29. At site B nitrate 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 of chlorinated 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 MASS DISCHARGE 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 33. Source: DDES, 2008 34. HAVE A LOOK 35.
WORKING GROUP Dra. Amparo Corts (UB-Farmcia) Dr. Jos M 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. G E A R Grup R+D de Geologia Econmica i Ambiental i
Hidrologia + D