Rhizoremediation of an historical contaminated site in Brescia (Italy): comparing the current emission of PCBs and PCDD/F to air from soil and other sources

Among the national priority polluted sites, the SIN Brescia Caffaro is located in a mid size city Brescia, (200,000 inhabitants) in northern Italy. The site derived from the activity of the former Caffaro s.p.a., a chemical factory among the largest former polychlorinated biphenyls (PCBs) producer in Europe, which produced such chemicals for more than 50 years up to mid 80\u2019. About 100 Ha of agricultural areas were contaminated by a mix of Persistent Organic Pollutants (POPs, mostly PCBs, dioxins, furans) and heavy metals (Hg, As) in variable concentrations, often exceeding the safety values. Such concentrations are orders of magnitude higher than the typical background anthropogenic values. Since the city of Brescia is located within an industrial district where current emission and secondary sources of POPs are also present (incinerators, smelters, etc.), this site represents a challenging case to evaluate the prevalence of a source over another and select the type of remediation activities. Concentrations of PCBs (more than 80 congeners) and PCDD/Fs in soil were measured averaging samples taken at surficial and deeper layers in 45 points located in the contaminated agricultural areas (totalling about 100 Ha). Concentrations of PCBs and PCDD/Fs were then used in the SoilPlus model (a multilayered dynamic multimedia fugacity model including a two layer dynamic air compartment) to predict hourly air concentrations of selected congeners and dioxin/furan classes for an entire simulation year. Such concentrations were compared to PCB and PCDD/F air concentrations measured in Brescia in five different areas at different seasonal intervals. Principal component analysis showed that calculated PCB fingerprints in air overlap with the measured ones, with seasonal concentrations varying accordingly (the predicted winter concentrations are closer to the measured), confirming that volatilization from soil determines current concentrations. The situation is different for PCDD/F where only furans seem more correlated with soil emissions, showing that dioxin sources are recent. A comparison of soil PCB fingerprints with Aroclor fingerprints confirms that the present congener mixture is mostly of highly chlorinated congeners, while PCDD/F fingerprints confirm the prevalence of furans.Such information is crucial to evaluate the impact and potential remediation effectiveness of rhizoremediation in presence of old and current sources

Role of rhizoremediation in a complex PCB soil contamination gradient

In the last two decades there has been a growing interest in bioremediation technologies which use plants and microorganisms to degrade organic chemicals such as Polychlorinated Biphenyls (PCBs) in contaminated sites. These techniques represent a good alternative to traditional remediation technologies, being cheaper, not disruptive and more suitable for large contaminated areas. Different studies have been conducted to investigate the potential of plant-microbe interactions in the remediation of organic chemical contaminated soils with respect to natural attenuation, providing useful data such as chemical degradation rates (K D ) or half lives (HL). Such a type of data can be used to predict soil concentration temporal trend, as well as the time needed to achieve legal limit when using plants and their associated rhizosphere microbe to remediate contaminated sites. In the present work, rhizoremediation experiment derived KD or HL for PCBs will be used as input parameters in an existing dynamic air-plant-litter-soil model (SoilPlusVeg) to estimate PCB concentration temporal trend in the soil of a National Relevance Site (SIN) for remediation located in Northern Italy (SINBrescia Caffaro). Analyses of sample collected in this area have shown the presence of a high spatial variability of PCB concentrations with values varying up to 3-4 orders of magnitude. Therefore it could be interesting to understand if rhizoremediation might be a suitable technique for the entire site. A number of long term simulations were run with SoilPlusVeg model for some PCBs and results were used to 1) compare the influence of natural attenuation vs. plant/microbe interactions on soil concentrations, 2) evaluate the effectiveness of rhizoremediation when a complex contamination gradient is present. Simulations results showed that although the importance of natural attenuation vs plant/microbe interactions depends on PCB physical chemical properties, when considering rhizoremediation experiment derived degradation rates the time requested to achieve legal limits decrease. However, rhizoremediation must be accurately implemented (in terms of species to be selected, their density, etc) to account for effective remediation, especially when complex patterns of contaminant are present

Cytotaxonomic and evolutionary considerations about karyotipic data of fishes from the Iguaçu River Basin in South of Brazil

The cytogenetic data available in the literature about the ichthyofauna of the Iguaçu River basin were analyzed in this review. The ichthyofauna was characterized by the high level of endemism and by the low diversity of species. Twenty-four of the eighty-one species were already karyotyped; six Characiformes, fourteen Siluriformes and four Perciformes. The chromosomal data showed the taxonomic and systematic complexity of the groups. Hypothesis related to the evolution of some Characiformes and Siluriformes groups from the Iguaçu River are proposed, as well as the utilization of karyotypic data for cytotaxonomy.<br>Nesta revisão são analisados os dados citogenéticos disponíveis na literatura relativos à ictiofauna da bacia do Rio Iguaçu, a qual é caracterizada pelo alto grau de endemismo e pela baixa diversidade de espécies. Das oitenta e uma espécies conhecidas, vinte e quatro já foram cariotipadas sendo 6 Characiformes, 14 Siluriformes e 4 Perciformes. Os dados cromossômicos evidenciam a complexidade taxonômica e sistemática dos grupos. São propostas hipóteses relacionadas à evolução de alguns grupos de Characiformes e Siluriformes do Rio Iguaçu, assim como o aproveitamento de dados cariotípicos para a citotaxonomia