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Phytoremediation Associate Professor Dr. Patana Anurakpongsatorn Department of Environmental Science Faculty of Science Kasetsart University Phytorem/Patana Anurak Remediation: conatminated soils Dig-and dump Encapsulation Washing Physicochemical techniques - Immobilization - Extraction Adverse effects: biological activity, soil structure and fertility costly Phytorem/Patana Anurak 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. Phytorem/Patana Anurak 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. Phytorem/Patana Anurak Phytoremediation ¾ ¾ ¾ ¾ ¾ ¾ Site restoration Partial decontamination Maintenance of biological activity and physical structure of soil Potentially cheap Visually unobtrusive Possibility of biorecovery of metals Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak คุณสมบัตขิ องพืชที่เหมาะตอการทํา Phytoremediation มีการเจริญเติบโตเร็ว ¾ มีความทนทานตอสารพิษ ¾ เปนพืชที่งายตอการปลูกและดูแลรักษา ¾ มีวงจรชีวิตสั้น ¾ ขยายพันธุหรือสืบพันธุไดในอัตราสูง ¾ มีปริมาณของมวลชีวภาพมาก ¾ มีการสะสมสารพิษหรือโลหะหนักที่ระดับสูง ¾ Phytorem/Patana Anurak Phytoremediation Phytorem/Patana Anurak Phytorem/Patana Anurak Phytoremediation processes to remove organic pollutants from soils Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak http://www.cee.vt.edu/ewr/environmental/teach/gwprimer/phyto/ bigdeep.gif Phytorem/Patana Anurak Methods of application ¾ In situ phytoremediation ¾ Ex situ phytoremediation with relocated contaminants -In vivo -In vitro Phytorem/Patana Anurak In situ phytoremediation ¾ 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 ¾ 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 Phytorem/Patana Anurak disposal or recovery of the contaminants. ¾ In vivo phytoremediation with relocated contaminants ¾ The sites where the contaminant is not accessible to the plants, such as in deep aquifers. ¾ The contaminant is extracted using mechanical means, then transferred to temporary treatment area . ¾ After treatment, cleansed soil or water can be returned to original place and the plants may be harvested for Phytorem/Patana disposal Anurak In vitro phytoremediation ¾ 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. ¾ Plant exudates which are released under stress (tarragon, Artemisia dracunculas var satiya) ¾ Limitation: length of time that enzyme remain active Phytorem/Patana Anurak Mechanisms of phytoremediation Phytoextraction/phytoaccumulation Phytopumping and water balance control Phytostabilization Phytotransformation/phytodegradation Phytovolatilization Rhizodegradation Phytorem/Patana Anurak Phytoextraction/phytoaccumulation Phytoextraction is the removal of a contaminant from the soil , ground water or surface water by live plant ¾ Phytoaccumulation occurred when the contaminant taken up by plant is not degraded rapidly or completely, resulting in an accumulation in the plant. Phytorem/Patana Anurak Phytoextraction Phytorem/Patana Anurak ที่มา:www.cee.vt.edu/.../gwprimer/phyto/accum.gif Phytoextract Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Limitation of Pb phytoextraction Two major limitations 1. Low Pb bioavailability in soil, and 2. The poor translocation of Pb from roots to shoots. Phytorem/Patana Anurak Hyperaccumulator plants ¾ ¾ ¾ ¾ 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 lesssoluble soil fractions compared to nonaccumulators. Metal concentrations in shoots of hyperacculators normally exceed those in roots. ¾ Metal hyperaccumulation has the ecological role of providing protection against fungal and insect attack. ¾ Such plants are endemic to area of natural mineralization and mine spoils. Exp.: Thlaspi spp. (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.Phytorem/Patana Anurak Hyperaccumulation plant: ¾ heavy metal hyperaccumulation is defined as accumulation of more than 0.1 % by dry weight in plant tissue (0.01 % for Cd) ¾ common element (Fe, Mn) hyperaccumulation is defined as more than 1 % by dry weight in plant tissue (0.01 % for Cd) ¾ 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). Phytorem/Patana Anurak 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. Phytorem/Patana Anurak 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 Phytorem/Patana Anurak Phytostabilization ¾ minimize migration of contaminants in soils ¾ Advantage of plant roots ability to alter soil environmental conditions, such as pH and soil moisture content ¾ Root exudates cause metals to precipitate, thus reducing bioavailability ¾ Advantage over phytoaccumulation is the disposal of the metal-laden plant material is not required ¾ 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 Phytorem/Patana Anurak contaminants with associated biota •Phytostabilization Phytorem/Patana Anurak Processes in Phytostabilization Phytorem/Patana Anurak Phytotransformation/phytodegradation ¾ Plant enzymes or enzyme co-factors ¾ Plants can degrade aromatic rings in the absence of microorganism ¾ Phenol degraded by horseradish, potato ( Solanum tuberosum) and white radish (Raphanus sativus) that contains peroxidase ¾ Poplar tree (Populus spp.) are capable to transform Trichloroethylene, TCE in soil and ground water ¾ 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 Phytorem/Patana Anurak phosphatase (transform organophosphate pesticides). Phytodegradation Phytorem/Patana Anurak ที่มา:http://online.caup.washington.edu/courses/larc433/Phyto/Components.htm Phytovolatilization ¾ Plants convert a contaminant into volatile form, thereby removing the contaminant from the soil or water from a contaminated site. ¾ Plants, possibly in association with microorgaisms, convert selenium to dimethyl selenide. It is a less toxic, volatile form of selenium. ¾ Some transgenic plants (e.g. Arabidopsis thaliana) converted organic and inorganic mercury salts to volatile, elemental form. Phytorem/Patana Anurak Phytovolatile Phytorem/Patana Anurak Rhizodegradation ¾ ¾ ¾ ¾ 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. Phytorem/Patana Anurak Rhizodegradation ¾ Plant litter and root exudates provide nutrients such as nitrate and phosphate, reducing the need to add costly fertilizer. ¾ Plant roots penetrate the soil, providing zones of aeration and stimulate aerobic biodegradation. ¾ Many plant molecules released by root die back and exudate resembled with contaminants and being as cosubstrates. Exp. Phenolic substances released by plants can stimulate the growth of PCB-degrading bacteria. Phytorem/Patana Anurak Phytorem/Patana Anurak Rhizoshere Rhizofiltration Phytorem/Patana Anurak Phytostimulation Phytorem/Patana Anurak ที่มา:www.menlh.go.id/…/artikel.php?article_id =1083 Phytorem/Patana Anurak Phytorem/Patana Anurak Soil column model Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Combined mechanisms Phytoextraction and phytovolatilization for removing excess selenium in soil. Poplar tree extracted the TCE from groundwater (phytoextraction) and TCE was degraded with in the plant (phytodegradation) Phytorem/Patana Anurak Phytorem/Patana Anurak Factors Factors affecting chemical uptake and distribution within living plants ¾ Physical and chemical properties of the compounds (water soluble, vapor pressure, molecular weight, octanol-water partition coefficient, Kow) ¾ Environmental characteristics (temperature, light) ¾ Contaminated media: soil (pH, organic matter, CEC, moisture content), water (pH, temperature) ¾ Plant characteristics ( type of root system, type of enzymes) Phytorem/Patana Anurak Chelating agents, EDTA ¾ EDTA (Ethylenediaminetetraacetic acid) ¾ 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. Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak การศึกษาการเปรียบเทียบประสิทธิภาพการสะสมสังกะสีใน ผักกาดเขียวปลี (Brassica juncea Coss.) และผักกาดเขียวกวางตุง (Brassica chinesis Linn.) ผักกาดเขียวปลี ผักกาดเขียวกวางตุง ที่มา :www.uky.edu/.../raft_veg/float.htg/must1215.jpg Phytorem/Patana Anurak และ www.omafra.gov.on.ca/.../facts/98-03315.jpg Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Dhatura innoxia ตนลําโพง Brassica juncea ผักกาดเขียวปลี Ipomoea carnea ผักบุงฝรั่ง ที่มา: www.uky.edu/.../raft_veg/float.htg/must1215.jpg, http://jardin-mundani.info/solanaceae/innoxia.jpgและ Phytorem/Patana Anurak http://www.hear.org/pier/imagepages/singles/ipomoea_carnea_ecoport_43724.htm Phytorem/Patana Anurak http://ourgardengang.tripod.com/whsuckitup.ht Phytorem/Patana Anurak m Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak Phytorem/Patana Anurak The End Phytorem/Patana Anurak
