Publicação
Studies on the biodegradation of atrazine in soils contamined with a commercial formulation containing atrazine and s-metolachlor
| Resumo: | Atrazine has been used worldwide since 1952 and is frequently detected above the levels established by regulatory authorities in consumption waters. Therefore, and because of its ecotoxicological properties, its use has been forbidden in most European countries, including Portugal. However, atrazine is still used in many countries worldwide. The main purpose of the present work was to examine the efficacy of the atrazinedegrading bacteria Pseudomonas sp. ADP (P. ADP) as bioaugmentation agent in soils contaminated with high doses (~20x and ~50xRD; RD Recommended dose) of the commercial formulation, Primextra S-Gold, that contains atrazine, and also S-metolachlor and benoxacor as main active ingredients. It was also tested the effect of combining bioaugmentation and biostimulation using soil amendment with trisodium citrate in open soil microcosms, with the purpose of scaling-up this bioremediation tool. Therefore, the effects of S-metolachlor and of benoxacor on P. ADP growth and activity were tested. Benoxacor was found to be innocuous to this bacterial strain and S-metolachlor to exert a slight to moderate inhibitory effect, especially for high concentrations in the soil (60 to 120 :g g-1 of soil). Subsequently, in mineralization experiments of 14C-UL-ring-atrazine in the presence of the high doses (~20x and ~50xRD) of Primextra S-Gold, lower levels of 14CO2 were liberated for higher doses of the commercial formulation. Soil amendment with trisodium citrate (Cs:Natz~50) allowed a slight augment in atrazine mineralization. These bioremediation treatments were also carried out in larger open soil microcosms proving to be efficient for the removal of atrazine from contaminated soils in only 5 days independent of citrate amendment. In parallel, we made an in silico comparative study between Atz proteins from Pseudomonas sp. ADP and the respective orthologues from other soil bacteria, in order to try to get indications about the organization and evolution of atrazine catabolism in soil |
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| Autores principais: | Costa, Ana Catarina da Silva Portinha e |
| Assunto: | Poluição de solos Contaminação de solos Teses de mestrado |
| Ano: | 2008 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Atrazine has been used worldwide since 1952 and is frequently detected above the levels established by regulatory authorities in consumption waters. Therefore, and because of its ecotoxicological properties, its use has been forbidden in most European countries, including Portugal. However, atrazine is still used in many countries worldwide. The main purpose of the present work was to examine the efficacy of the atrazinedegrading bacteria Pseudomonas sp. ADP (P. ADP) as bioaugmentation agent in soils contaminated with high doses (~20x and ~50xRD; RD Recommended dose) of the commercial formulation, Primextra S-Gold, that contains atrazine, and also S-metolachlor and benoxacor as main active ingredients. It was also tested the effect of combining bioaugmentation and biostimulation using soil amendment with trisodium citrate in open soil microcosms, with the purpose of scaling-up this bioremediation tool. Therefore, the effects of S-metolachlor and of benoxacor on P. ADP growth and activity were tested. Benoxacor was found to be innocuous to this bacterial strain and S-metolachlor to exert a slight to moderate inhibitory effect, especially for high concentrations in the soil (60 to 120 :g g-1 of soil). Subsequently, in mineralization experiments of 14C-UL-ring-atrazine in the presence of the high doses (~20x and ~50xRD) of Primextra S-Gold, lower levels of 14CO2 were liberated for higher doses of the commercial formulation. Soil amendment with trisodium citrate (Cs:Natz~50) allowed a slight augment in atrazine mineralization. These bioremediation treatments were also carried out in larger open soil microcosms proving to be efficient for the removal of atrazine from contaminated soils in only 5 days independent of citrate amendment. In parallel, we made an in silico comparative study between Atz proteins from Pseudomonas sp. ADP and the respective orthologues from other soil bacteria, in order to try to get indications about the organization and evolution of atrazine catabolism in soil |
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