Full text
| |
| Author(s): |
João Vasconcellos de Almeida
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2010-04-09 |
| Examining board members: |
Pio Colepicolo Neto;
Nadja Cristhina de Souza Pinto Lardner;
Nair Sumie Yokoya
|
| Advisor: | Pio Colepicolo Neto |
| Abstract | |
Algae show a great biodiversity and occupy many different ecological niches. Besides being essential for the maintenance that allow life on Earth, algae are on the basis of aquatic food chains and they suffer with continuous residue discharge that comes from different human activities. However, once algae are exposed to pollutants, biomarkers can indicate its presence on the environment. The aim of this work was on the characterization of benzo(a)pyrene (BaP; a polycyclic aromatic hydrocarbon (PAH) derived from crude oil and from incomplete combustion of organic matter) toxicity against the red macroalga Gracilaria birdiae, a marine brazillian Rhodophyta. BaP toxicity in marine water was investigated under different exposure concentrations after acute (24 and 96h) and chronic (7 and 15 days) conditions. At the end of the exposures time, some of the algae`s biochemical and physiological biomarkers were analyzed: growth rate (GR); two antioxidant defenses: the low molecular weight peptide glutathione (GSH) and superoxide dismutase (SOD) enzyme activity; glutathione disulfide (GSSG) levels; the macroalga photosynthetic capacity; and the general colour aspect. Increased BaP concentrations led to a decrease of GR values. From GR data it was possible to obtain an inhibition growth curve and the respective BaP IC50 for a 15-day exposure time period with value of 69 ng/mL. After different BaP exposure conditions, including IC50, exposed algae presented decreased GSH levels, the same effects observed for GSSG (except for 96h exposure). The photosynthetic yield, SOD activity and colour aspect of G. birdiae appeared to be more resistant systems against BaP, and were affected only in higher BaP concentrations (10 to 20 µg/mL). In such situations, G. birdiae lost its red colour, which was accompanied by considerable photosynthetic parameters (i.e., rETR, RQE, Ik, β) decay. In a different approach, some experiments were done in order to discover any BaP clean-up and bioremediation played by G. birdiae. Preliminary results suggests that the alga has low remediation efficiency, although more investigations need to be done to confirm this. In summary, the results presented here show similar tendencies with literature data in respect of BaP toxicity against living organisms. Even though G. birdiae presented reasonable resistance to BaP, it was possible to identify some of the alga`s biochemical systems as BaP exposure biomarkers. This situation can be useful for impacted areas assessment and management. (AU) | |