RESUMEN
Lithuania is representative of maritime to continental climate, no water limitation, and moderate ground-level ozone (O3) pollution. We investigated the trends of meteorological variables and O3 and how these environmental conditions associate with tree health from 2001 onward. Ozone metrics for forest protection, based on Accumulated O3 exposure Over a Threshold of X ppb (AOTX) or on Phytotoxic O3 Dose over a Y threshold (PODY), were modeled at nine ICP-Forests plots over the time period 2001-2014. Tree-response indicators, i.e. crown defoliation and visible foliar O3 injury, were assessed during annual field surveys carried out at each ICP-Forests plot over the time period 2007-2017. Mann-Kendall and Sen statistical tests were applied to estimate changes over time of meteorological variables, response indicators and O3 metrics. Finally, the O3 metrics were correlated (Spearman test) to the response indicators over the common period 2007-2014. Over this time period, trend analyses revealed an increasingly hotter (+0.27⯰Câ¯decade-1, on average) and drier climate (rainfall, -48â¯mmâ¯decade-1). A reduction was found for O3 annual mean (-0.28â¯ppbâ¯decade-1, on average) and AOT40 (-2540â¯ppb·hâ¯decade-1, on average) whereas an increase was found for POD0 (+0.40â¯mmolâ¯m-2â¯decade-1, on average). Visible foliar O3 injury increased (+0.17%â¯decade-1), while an improvement of the crown conditions (-5.0%â¯decade-1) was observed. AOT40 was significantly associated with crown defoliation while PODY and soil water content were correlated with visible foliar O3 injury. As visible foliar O3 injury was negligible in all the studied species, the results suggest that moderate O3 pollution (approximately 30â¯ppb as annual average) does not induce biologically significant effects on this forest vegetation under the current conditions, however the overall O3 risk (POD0) is expected to increase in the future under a hotter and drier climate.
Asunto(s)
Contaminantes Atmosféricos/efectos adversos , Monitoreo del Ambiente/métodos , Bosques , Ozono/efectos adversos , Árboles/fisiología , Contaminantes Atmosféricos/análisis , Lituania , Ozono/análisis , Árboles/efectos de los fármacosRESUMEN
Continuous ozone concentration measurements at rural sites in Lithuania have been performed since 1982. Long-term ozone data show an increasing trend 0.4 ppb y(-1) in annual mean concentrations during the period 1982-2008, although ozone peak values show an insignificant tendency to decrease. Several studies were performed to evaluate the ozone effect on the main plant species of Lithuanian forests. A strong positive correlation was found between values for the accumulated doses over a threshold of 40 ppb index and the defoliation of Fraxinus excelsior trees in Lithuanian forests during 1991-2008. A strong correlation was found between ozone exposure and the proportion of healthy F. excelsior, Betula sp., and Alnus incana, trees indicating that in Lithuania the deciduous species are more sensitive to ozone than conifers and that healthier trees may be better indicators of the changing environment. The results of the studies suggest that the observed levels of ozone are sufficiently high to have negative effects on the vegetation in Lithuania.
Asunto(s)
Oxidantes Fotoquímicos/toxicidad , Ozono/toxicidad , Árboles/efectos de los fármacos , Aire/análisis , Ecosistema , Lituania , Oxidantes Fotoquímicos/análisis , Ozono/análisis , Hojas de la Planta/efectos de los fármacosRESUMEN
The analysis of data of the ground-level ozone concentration and accumulated ozone exposure over a threshold of 40 ppb (AOT40) in the rural areas of Lithuania is presented. Trends in the annual ozone mean, 95th and 25th percentiles were determined as statistically not significant at Preila and Rugsteliskes sites during the 1994-2004 period. Trends in the ozone concentration and its percentiles in the air masses arriving to Preila station in "polluted" and "unpolluted" sectors have been examined. Statistically significant changes in the ozone annual mean and 25th percentile were found in air masses in both "polluted" and "unpolluted" sectors in the 1988-2002 period. The trend analysis in the ozone monthly mean and percentiles for each month of the year revealed the main changes in the ozone level in both sectors during January-May. Insignificant downward trends in monthly 95th percentile in "unpolluted" sector and upward trends in "polluted" sector were found during summer months. Values of AOT40 for the protection of forests as well as crops and semi-natural vegetation were determined during the 1994-2004 period. The estimated AOT40 values for the protection of forests were lower than the critical level at Lithuanian rural sites but AOT40 values for the protection of crops and semi-natural vegetation were found to be higher than the critical level at both sites.
Asunto(s)
Contaminantes Atmosféricos/análisis , Ozono/análisis , Población Rural , Monitoreo del Ambiente/métodos , LituaniaRESUMEN
Due to the dynamic nature of the atmosphere, substantial amounts of gaseous and particulate pollutants are transported to the areas distant from their sources. In order to determine the regional concentration levels of atmospheric pollutants in Lithuania, concentrations of gaseous O3, SO2, NO2 and other pollutants have been measured at the Preila background station (55 degrees 20' N and 21 degrees 00' E, 5 m a.s.l.) since 1981. The long-term concentration data set enabled us to get temporal trends, both on a seasonal and longer time scale, to identify source areas of pollutants and to relate them to the emission data. Based on the data obtained, the different tendencies in the pollutant concentration changes were revealed. Positive trends for ozone (of 2.9% per year during 1983-2000) and a distinct negative trend for both sulphur dioxide (of 3.8% per year during 1981-2000) and nitrogen dioxide (of 3.8% per year during 1983-2000) were found. The air mass back-trajectory analysis was used to assess the source region of air pollutants transported to Lithuania. The pollutant concentration levels were compared with their emission changes in Europe and Lithuania. The general trends in SO2 as well as in NO2 concentrations observed are consistent with changes in SO2 and NO2 emissions in Europe and Lithuania.