Year: 2013
Type: article
Abstract: One of the main routes through which pharmaceuticals may enter the environment consists in the medication of livestock. In fact, in Europe the annual national sales of active substance for veterinary consumption reach hundreds of tons. After medication, up to 90% of the administered medicine dose may be excreted unaltered and, following the use of manure as fertilizer, soils and waters are contaminated. The present work focuses on the effects and eventual accumulation on woody and herbaceous plants of sulfonamides, a group of antimicrobial agents (from now on called antibiotics) frequently detected in agricultural ecosystems, whose persistence poses a serious risk to soil and water living organisms. The thesis consists of 7 chapters, presenting, in the first one, a general introduction on the antibiotic presence in the environment and its consequences on the growth and development of exposed living organisms. Subsequently, from chapter 2 to chapter 6, various experimental trials are presented, some of them carried out under laboratory conditions and others in greenhouse. More specifically, chapter 2 reports the first study performed, which deals with Salix fragilis L. plant response and the accumulation of sulfadimethoxine antibiotic, added in the nutrient solution at doses ranging from 155 to 620 mg l-1. Such a study highlights the potential of this woody species to absorb and accumulate the active molecule at the level of root apparatus. Chapter 3 retraces the experimental design of chapter 2, with the difference that Salix fragilis L. plants were exposed to environmental relevant sulfadimethoxine doses, from 0.01 up 10 mg l-1. The trial had demonstrated that no adverse effects on the growth of willow plants appeared up to 1 mg l-1 of antibiotic. Conversely, increasing levels of the antibiotic caused important alterations of the willow root architecture. Chapters 4 and 5 consider, respectively, the effects and accumulation of a different sulfonamide on Salix fragilis L. and Zea mays L. plants, grown in a soil spiked with 10 and 200 mg kg-1 of sulfadiazine. Moreover, its impact on the composition of root associated soil microbial community and on the activities of selected enzymes was analyzed. The last study, presented in chapter 6, focuses on alterations induced by about 10 mg l-1 of sulfadimethoxine and sulfamethazine on Hordeum vulgare L. root structure and function. This chapter highlights the strong effects of the antibiotics, not only on the root apparatus morphology, but also on the membrane integrity of root cells. To conclude (chapter 7), it is highlighted that Salix fragilis L. seems to better accumulate and withstand the active molecules tested than Zea mays L. and Hordeum vulgare L., while the herbaceous species are more vulnerable to this kind of pollutant exposure and, therefore, not recommended for eventual remediation purposes. Furthermore, chapter 7 notes the adverse consequences on the functional and structural diversity of the soil microbial community.
Author: Lucia Michelini
Language: English
Subfield: Pollution
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W2276699785