Phytoremediation of soils polluted with chloroacetanilide herbicides phyto- = plant-related remediare = make something usable again Portoroz 2005

Phytoremediation - growing plants in polluted soil u Crops, weeds u In theory: simple (?) u Take pollutants up u Transport, evaporate u Detoxify –metabolism –accumulation »harvest: removal Portoroz 2005

u Advantages –inexpensive (vs. traditional) –agricultural - "green" –public acceptance: very good u Limitations –time consuming »bioavailability –season-dependent –“final” pollution –pollutant phytotoxic, such as herbicides - project Good - not so good Portoroz 2005

Research project - phytoremediation of a polluted site Portoroz 2005 u 3 km from Lake Balaton u Chemical plant's "waste pond"; 45 ha, ca. 6 m deep u Phytotoxic cocktail –pesticides, heavy metals, explosives, intermediates... u Goal: reduce/eliminate u Chose the right plant(s) u Chloroacetanilide herbicides at ca M

u Widely used in several crops u Monoculture - large quant. u Hazard –environmental toxicity –human health u Selective action –due to differential metabolic rates –role of glutathione Chloroacetanilide herbicides Portoroz 2005

u Tripeptide:  -L-Glu-L-Cys-Gly Glutathione (GSH) –Presence of thiol (-SH) group: highly reactive »reducing agent »nucleophile –In phytoremediation »protection against oxidative stress »pollutant detoxification via GSH-conjugation Portoroz 2005

Detoxification system’s capacity: GSH levels & enzyme activity Experimental plants: maize and poplars GSH conjugation of chloroacetanilides Portoroz 2005

u Excellent candidates –rapid growth –large biomass –large genetic pool –root depth Why poplar trees? Why maize plants? u Excellent candidates –rapid growth –large biomass –large genetic pool –tolerance to CAs Portoroz 2005

u Ability of maize (14 hybrids) to take up, tolerate, and detoxify 8 CA herbicides - excellent »effects of GSH/GST modifyers u Ability of poplars (11 clones) to take up, tolerate, and detoxify 8 CA herbicides - good, marginal detoxify 8 CA herbicides - good, marginal »effects of GSH/GST modifyers u Rates of herbicide uptake and translocation u Identity of herbicide metabolites u Rates of herbicide metabolism u Best hybrids and clones selected for field studies Laboratory studies Portoroz 2005

u April 1999: 1200 maize plants + MG vigorous growth –discontinued: deep pollution, hungry boars u March 2002: 900 small poplar trees - poor survival –drought, hungry deers u April 2003: 700 small poplar trees (7 clones) - ca. 40 % survive in 2004 Field studies Portoroz 2005 u 2005: maintenance, monitoring (plants, pollutants, soil microbial life) - AASW 2006

The End Portoroz 2005