SEFS 8 - Symposium for European Freshwater Sciences July 1-5, 2013, Münster, Germany Abstract Book page 443 SS06 VARIABILITY OF HAZARDOUS SUBSTANCES AND MICROBIAL PROCESSES IN RIVERINE SEDIMENTS SUBJECT TO FLUCTUATING FLOW CONDITIONS Zoppini A.1, Ademollo N.1, Amalfitano S.1, Casella P.1, Capri S.1, Patrolecco L.1, Polesello S.2 1Water Research Institute- National Research Council (IRSA-CNR), Via Salaria km 29,300, 00015 Monterotondo (Rome), Italy 2Water Research Institute- National Research Council (IRSA-CNR), Via del Mulino, 19, 20861 Brugherio (MB), Italy The global mean rates of precipitation and evapotranspiration are expected to increase, causing flood and drought events of higher intensity and frequency in the Mediterranean area as well as in several other regions of the world. Considering the risks and consequences of climate extremes, the southern Mediterranean temporary rivers represent either significant water resources directly accessible for agricultural and industrial purposes, either aquatic ecosystems to be preserved. In Europe, the Water Framework Directive (WFD 2000/60/EC) includes a list of 33 priority substances with the aim to regulate the limits of concentrations in surface waters and to develop environmental quality standards for sediment and biota. This list includes polycyclic aromatic hydrocarbons (PAHs) and nonylphenols (NPs) both potentially hazardous to human health and natural ecosystems. Temporary rivers are naturally characterized by a high variability of the hydrological cycle that influences the availability of nutrient and organic matter (OM). The microbial transformation of the detritus to biomass in the sediments, is a key processes with regard to the C-flux in the lotic systems as it represents the link between sedimentary OM (including pollutants) and the food web. The results obtained in the frame of the EU Project MIRAGE, give a snapshot of the variability of two classes of pollutants and microbial processes in sediments from a temporary river of Southern Italy, in different hydrologic conditions from flood to drought. The observed changes in the sediments were mainly related to PAH contaminations: large mobility during high flow and accumulation during low flow. The contamination by NPs was less affected by hydrological conditions and the level of the contamination can be considered rather constant. Changes were evident in the microbial strategies that induced a progressive decline of the functional microbial properties passing from high flow to no flow. It is interesting to note that drought acts both on the reduction of bacterial cell activity and on micropollutant concentration (i.e. PAHs). The significant reduction of the microbial metabolic rates does not imply the complete cessation of the C-flux, as resident communities showed residual activities.The management of temporary rivers have to consider the different diffusion of micropollutants in relation to hydrological regime as well as the diffrent contribution of the microbial activity to OM degradation.
Variability of hazardous substances and microbial processes in riverine sediments subject to fluctuating flow conditions.
Zoppini A;Ademollo N;Amalfitano S;Capri S;Polesello S
2013
Abstract
SEFS 8 - Symposium for European Freshwater Sciences July 1-5, 2013, Münster, Germany Abstract Book page 443 SS06 VARIABILITY OF HAZARDOUS SUBSTANCES AND MICROBIAL PROCESSES IN RIVERINE SEDIMENTS SUBJECT TO FLUCTUATING FLOW CONDITIONS Zoppini A.1, Ademollo N.1, Amalfitano S.1, Casella P.1, Capri S.1, Patrolecco L.1, Polesello S.2 1Water Research Institute- National Research Council (IRSA-CNR), Via Salaria km 29,300, 00015 Monterotondo (Rome), Italy 2Water Research Institute- National Research Council (IRSA-CNR), Via del Mulino, 19, 20861 Brugherio (MB), Italy The global mean rates of precipitation and evapotranspiration are expected to increase, causing flood and drought events of higher intensity and frequency in the Mediterranean area as well as in several other regions of the world. Considering the risks and consequences of climate extremes, the southern Mediterranean temporary rivers represent either significant water resources directly accessible for agricultural and industrial purposes, either aquatic ecosystems to be preserved. In Europe, the Water Framework Directive (WFD 2000/60/EC) includes a list of 33 priority substances with the aim to regulate the limits of concentrations in surface waters and to develop environmental quality standards for sediment and biota. This list includes polycyclic aromatic hydrocarbons (PAHs) and nonylphenols (NPs) both potentially hazardous to human health and natural ecosystems. Temporary rivers are naturally characterized by a high variability of the hydrological cycle that influences the availability of nutrient and organic matter (OM). The microbial transformation of the detritus to biomass in the sediments, is a key processes with regard to the C-flux in the lotic systems as it represents the link between sedimentary OM (including pollutants) and the food web. The results obtained in the frame of the EU Project MIRAGE, give a snapshot of the variability of two classes of pollutants and microbial processes in sediments from a temporary river of Southern Italy, in different hydrologic conditions from flood to drought. The observed changes in the sediments were mainly related to PAH contaminations: large mobility during high flow and accumulation during low flow. The contamination by NPs was less affected by hydrological conditions and the level of the contamination can be considered rather constant. Changes were evident in the microbial strategies that induced a progressive decline of the functional microbial properties passing from high flow to no flow. It is interesting to note that drought acts both on the reduction of bacterial cell activity and on micropollutant concentration (i.e. PAHs). The significant reduction of the microbial metabolic rates does not imply the complete cessation of the C-flux, as resident communities showed residual activities.The management of temporary rivers have to consider the different diffusion of micropollutants in relation to hydrological regime as well as the diffrent contribution of the microbial activity to OM degradation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
