Using plant biomonitors and flux modelling to develop O 3 dose-response relationships in Catalonia

Filella I., Peñuelas J., Ribas A. (2005) Using plant biomonitors and flux modelling to develop O 3 dose-response relationships in Catalonia. Environmental Pollution. 134: 145-151.
Enllaç
Doi: 10.1016/j.envpol.2004.07.007

Resum:

We used tobacco Bel-W3 biomonitoring data and ozone flux modelling (WINDEP model) with the aim of developing the absorbed dose-response relationship, and comparing this approach with the most commonly used AOT40 (the sum of hourly ozone concentrations above a cut-off of 40 ppb during daylight hours, when global radiation exceeds 50 W m -2) in the estimation of exposure-damage curves. Leaf damage values were more related to OAD 15 days, potential (potential ozone absorbed dose calculated over 15 consecutive days) than to AOT40 in all the studied stations. An OAD 15 days, potential of 180 mg m -2 was found to be the threshold for damage to the most sensitive species in this region under well watered conditions. The results show the applicability of the flux approach for risk assessment at the local scale, the improvement of the ozone damage estimation when the potential absorbed dose is modelled and used instead of just the ozone exposure, and finally, the possibilities opened by the use of biomonitoring networks. Modelling of biomonitors ozone absorbed dose improves damage estimation in comparison with exposure indices such as AOT40. © 2004 Elsevier Ltd. All rights reserved.

Llegeix més

Contrasting effects of ozone under different water supplies in two Mediterranean tree species

Ribas A., Peñuelas J., Elvira S., Gimeno B.S. (2005) Contrasting effects of ozone under different water supplies in two Mediterranean tree species. Atmospheric Environment. 39: 685-693.
Enllaç
Doi: 10.1016/j.atmosenv.2004.10.022

Resum:

The effects of ozone (O 3) exposure under different water availabilities were studied in two Mediterranean tree species: Quercus ilex and Ceratonia siliqua. Plants were exposed to different O 3 concentrations in open top chambers (charcoal-filtered air (CF), non-filtered air (NF)) and non-filtered air plus 40 ppb v of O 3 ((7:00-17:00 solar time) (NF+)) during 2 years, and to different water regimes (IR, sample irrigation, and WS, reduced water dose to 50%) through the last of those 2 years. AOT40 in the NF+ treatment was 59265 ppb v h (from March 1999 to August 1999) while in the NF treatment, the AOT40 was 6727 ppb v h for the same period. AOT40 was always 0 in the CF treatment. WS plants presented lower stomatal conductances and net photosynthetic rates, and higher foliar N concentrations than IR plants in both species. The irrigation treatment did not change the response trends to ozone in Q. ilex, the most sensitive species to O 3 ambient concentrations, but it changed those of C. siliqua, the least sensitive species, since its ozone-fumigated WS plants did not decrease their net photosynthetic rates nor their biomass accumulation as it happened to its ozone-fumigated IR plants. These results show interspecific variations in O 3 sensitivity under different water availabilities. © 2004 Elsevier Ltd. All rights reserved.

Llegeix més

Ozone exposure induces the activation of leaf senescence-related processes and morphological and growth changes in seedlings of Mediterranean tree species

Ribas A., Peñuelas J., Elvira S., Gimeno B.S. (2005) Ozone exposure induces the activation of leaf senescence-related processes and morphological and growth changes in seedlings of Mediterranean tree species. Environmental Pollution. 134: 291-300.
Enllaç
Doi: 10.1016/j.envpol.2004.07.026

Resum:

Four Mediterranean tree taxa, Quercus ilex subsp. ilex, Quercus ilex subsp. ballota, Olea europaea cv. vulgaris and Ceratonia siliqua, were exposed to different ozone (O 3) concentrations in open top chambers (OTCs) during 2 years. Three treatments were applied: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air plus 40 ppb v of O 3 (NF+). The photochemical maximal efficiency, Fv/Fm, decreased in NF+ plants during the second year of exposure, especially during the most stressful Mediterranean seasons (winter and summer). An increase of δ 13C was found in three of the four studied species during the first year of exposure. This finding was only maintained in C. siliqua during the second year. Decreases in the chlorophyll content were detected during the first year of fumigations in all the species studied, but not during the second year. The NF+ treatment induced changes in foliar anatomical characteristics, especially in leaf mass per area (LMA) and spongy parenchyma thickness, which increased in some species. A reduction in N content and an increase in δ 15N were found in all species during the second year when exposed in the NF+ OTCs, suggesting a change in their retranslocation pattern linked to an acceleration of leaf senescence, as also indicated by the above mentioned biochemical and anatomical foliar changes. The two Q. ilex subspecies were the most sensitive species since the changes in N concentration, δ 15N, chlorophyll, leaf area, LMA and biomass occurred at ambient O 3 concentrations. However, C. siliqua was the most responsive species (29% biomass reduction) when exposed to the NF+ treatment, followed by the two Q. ilex subspecies (14-20%) and O. europaea (no significant reduction). Ozone resistance of the latter species was linked to some plant traits such as chlorophyll concentrations, or spongy parenchyma thickness. Ozone induces species-specific leaf senescence-related processes and morphological and growth changes in seedlings of Mediterranean tree species. © 2004 Elsevier Ltd. All rights reserved.

Llegeix més