Phytoremediation. Associate Professor Dr. Patana Anurakpongsatorn Department of Environmental Science Faculty of Science Kasetsart University

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1 Phytoremediation Associate Professor Dr. Patana Anurakpongsatorn Department of Environmental Science Faculty of Science Kasetsart University

2 Remediation: conatminated soils Dig-and dump Encapsulation Washing Physicochemical techniques - Immobilization - Extraction Adverse effects: biological activity, soil structure and fertility costly

3 Natural attenuation Natural attenuation defined as the natural, nonengineered process of degradation of xenobiotics by the indigenous microbial population. It is the simplest form of bioremediation. US.EPA defines Natural attenuation or intrinsic remediation as a combination of degradation, dispersion, dilution, sorption, volatilization and chemical and biological stabilization of contaminants.

4 Phytoremediation Phytoremediation is defined as the use of plants to remove pollutants from the environment or to render them harmless. Ideal plant species to remediate pollutant contaminated soil would be a high biomass producing crop that can both tolerate and accumulate the contaminants of interest.

5 Phytoremediation Site restoration Partial decontamination Maintenance of biological activity and physical structure of soil Potentially cheap Visually unobtrusive Possibility of biorecovery of metals

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8 ค ณสมบ ต ของพ ชท เหมาะต อการท า Phytoremediation ม การเจร ญเต บโตเร ว ม ความทนทานต อสารพ ษ เป นพ ชท ง ายต อการปล กและด แลร กษา ม วงจรช ว ตส น ขยายพ นธ หร อส บพ นธ ได ในอ ตราส ง ม ปร มาณของมวลช วภาพมาก ม การสะสมสารพ ษหร อโลหะหน กท ระด บส ง

9 Phytoremediation

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11 Phytoremediation processes to remove organic pollutants from soils

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15 Methods of application In situ phytoremediation Ex situ phytoremediation with relocated contaminants -In vivo -In vitro

16 In situ phytoremediation Placement of live plants in - contaminated surface water, soil or sediment that is contaminated, or - in soil or sediment that is in contact with contaminated groundwater Contaminant must be physically accessible to the root If phytomechanism consists of only uptake and accumulation, the plants may be harvested and removed from the site after remediation for disposal or recovery of the contaminants. disposal or recovery Phytorem/Patana of the contaminants. Anurak

17 In vivo phytoremediation with relocated contaminants The sites where the contaminant is not accessible to the plants, such as in deep aquifers. The contaminant is extracted using mechanical means, then transferred to temporary treatment area. After treatment, cleansed soil or water can be returned to original place and the plants may be harvested for Phytorem/Patana disposal Anurak

18 In vitro phytoremediation Applying via component or live plants such as extracted enzymes, plant extracts to a contaminated pond or wetland or enzyme impregnated porous barrier in a contaminated groundwater plume. Plant exudates which are released under stress (tarragon, Artemisia dracunculas var satiya) Limitation: length of time that enzyme remain active

19 Mechanisms of phytoremediation Phytoextraction/phytoaccumulation Phytopumping and water balance control Phytostabilization Phytotransformation/phytodegradation Phytovolatilization Rhizodegradation

20 Phytoextraction/phytoaccumulation Phytoextraction is the removal of a contaminant from the soil, ground water or surface water by live plant Phytoaccumulation occurred when the contaminant taken up by plant is not degraded rapidly or completely, resulting in an accumulation in the plant.

21 ท มา:www /.../gwprimer/phyto Phytoextraction phyto/accum.gif

22 Phytoextract

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26 Limitation of Pb phytoextraction Two major limitations 1. Low Pb bioavailability in soil, and 2. The poor translocation of Pb from roots to shoots.

27 Hyperaccumulator plants Capable to accimulate potential phytotoxic elements more than 100x concentration than those of nonaccumulators. Have strongly expressed metal sequestration mechanisms. Some species may capable of molishing metals from less- soluble soil fractions compared to nonaccumulators. Metal concentrations in shoots of hyperacculators normally exceed those in roots. Metal hyperaccumulation has the ecological role of providing protection against fungal and insect attack. Such plants are endemic to area of natural mineralization and mine spoils. Exp.: Thlaspi spp.. (Brassicaceae( Brassicaceae) ) can accumulate more than 3% Zn, 0.5% Pb,, 0.1% Cd in their shoots and some spp.. of Alyssum (Brassicaceae)) shown to accumulate over 1% Ni.

28 Hyperaccumulation plant: heavy metal hyperaccumulation is defined as accumulation of more than 0.1 % by dry weight in plant tissue (0.01 % for Cd) common element (Fe, Mn) hyperaccumulation is defined as more than 1 % by dry weight in plant tissue (0.01 % for Cd) If remediation goal is to harvest after hyperaccumulated, then selected the plant which be able to translocate the contaminant from root into above ground tissue, such as shoots, and leaves, is more easy than harvest the root (if the contaminant remained in the root).

29 Limitation of hyperaccumulator By plant productivity and concentration of metals achieved. Zn hyperaccumulator, Thlaspi caerulescens, are limited for using in the field because of individual plants are very small and slow growing.

30 Phytopumping Phytopumping and water balance control Remove or minimize migration of contaminants Plants as organic pumps, as part of the transpiration process Willow tree (Salix( spp.) may use up to 200 L of water per day Treat systems for contaminated groundwater in shallow aquifers

31 Phytostabilization minimize migration of contaminants in soils Advantage of plant roots ability to alter soil environmental conditions, such as ph and soil moisture content Root exudates cause metals to precipitate, thus reducing bioavailability Advantage over phytoaccumulation is the disposal of the metal-laden laden plant material is not required By choosing and maintaining an appropriate cover of plant species, coupled with appropriate soil amendments, it may be possible to stabilize certain contaminants (particularly metals) in soil and reduce the interaction of these contaminants with associated biota contaminants with associated biota

32 Phytostabilization

33 Processes in Phytostabilization

34 Phytotransformation/phytodegradation Plant enzymes or enzyme co-factors Plants can degrade aromatic rings in the absence of microorganism Phenol degraded by horseradish, potato ( Solanum tuberosum) ) and white radish (Raphanus( sativus) that contains peroxidase Poplar tree (Populus( spp.) are capable to transform Trichloroethylene, TCE in soil and ground water Interested enzymes in phytoremediation: dehydrogenase (transform chlorinated compounds), peroxidase (transform phenolic compounds), nitroreductase (transform explosive and other nitrate compounds), nitrilase (transform cyanated aromatic compounds) and phosphatase (transform organophosphate pesticides).

35 Phytodegradation ท มา:http ://online.caup.washington.edu/courses/larc433/phyto/components.htm

36 Phytovolatilization Plants convert a contaminant into volatile form, thereby removing the contaminant from the soil or water from a contaminated site. Plants, possibly in association with microorgaisms,, convert selenium to dimethyl selenide.. It is a less toxic, volatile form of selenium. Some transgenic plants (e.g. Arabidopsis thaliana) converted organic and inorganic mercury salts to volatile, elemental form.

37 Phytovolatile

38 Rhizodegradation It is a biological treatment of a contaminant by enhanced bacterial and fungal activity in the plant rhizosphere. The rhizosphere is a zone of increased microbial density and activity at the root surface (e.g. legume). Plants and microoranisms often have symbiotic relationship making the root zone or rhizosphere an area of very active microbial activity. Plants can moderate the geochemical environment in the rhizosphere,, providing idea conditions for bacteria and fungi to grow and degrade organic contaminants.

39 Rhizodegradation Plant litter and root exudates provide nutrients such as nitrate and phosphate, reducing the need to add costly fertilizer. Plant roots penetrate the soil, providing zones of aeration and stimulate aerobic biodegradation. Many plant molecules released by root die back and exudate resembled with contaminants and being as co- substrates. Exp. Phenolic substances released by plants can stimulate the growth of PCB-degrading bacteria.

40 Rhizoshere

41 Rhizofiltration

42 ท มา: Phytostimulation /artikel.php?article_id=1083

43 Soil column model

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47 Combined mechanisms Phytoextraction and phytovolatilization for removing excess selenium in soil. Poplar tree extracted the TCE from groundwater (phytoextraction( phytoextraction) ) and TCE was degraded with in the plant (phytodegradation)

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49 Factors Factors affecting chemical uptake and distribution within living plants Physical and chemical properties of the compounds (water soluble, vapor pressure, molecular weight, octanol-water partition coefficient, Kow) Environmental characteristics (temperature, light) Contaminated media: soil (ph, organic matter, CEC, moisture content), water (ph, temperature) Plant characteristics ( type of root system, type of enzymes)

50 Chelating agents, EDTA EDTA (Ethylenediaminetetraacetic( acid) Inceasing metal (esp. Pb) desorption from soil into soil solution and also greatly increased the translocation of metal from root to shoot through prevention of cell wall retention.

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55 การศ กษาการเปร ยบเท ยบประส ทธ ภาพการสะสมส งกะส ใน ผ กกาดเข ยวปล (Brassica juncea Coss.) และผ กกาดเข ยวกวางต ง (Brassica chinesis Linn.) ผ กกาดเข ยวปล ผ กกาดเข ยวกวางต ง ท มา : และ

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60 Dhatura innoxia ต นล าโพง Brassica juncea ผ กกาดเข ยวปล Ipomoea carnea ผ กบ งฝร ง ท มา:

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72 The End