Environmental levels of pahs and other svocs in a petrochemical area. Combining monitoring and modelling tools
- Autores: Noelia Domínguez Morueco
- Directores de la Tesis: Martí Nadal Lomas (dir. tes.), Marta Schuhmacher Ansuategui (codir. tes.), Jordi Sierra Llopart (codir. tes.)
- Lectura: En la Universitat Rovira i Virgili ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Ana Sofía Pacheco Marques Augusto (presid.), Montserrat Mari Marcos (secret.), Esther Martí Verge (voc.)
- Programa de doctorado: Programa de Doctorado en Nanociencia, Materiales e Ingeniería Química por la Universidad Rovira i Virgili
- Materias:
- Enlaces
- Tesis en acceso abierto en: hdl.handle.net TDX
- Resumen
Pollution is the contamination of the environment by introduction of contaminants or pollutants in concentrations that may cause damage to environment and harm organisms (humans, plants and animals). According to European Environment Agency (EEA) air pollution is the single largest environmental health risk in Europe, and can cause respiratory problems and shorten lifespans. Atmospheric transport is the primary distribution pathway of substances, moving these pollutants from atmospheric emission sources (natural or anthropogenic) via deposition to terrestrial and aquatic ecosystems. Among these substances there are the called semi-volatile organic compounds (SVOCs), characterized by their high toxicity, the recalcitrant to degradation processes character and their potential for long-range atmospheric transport (LRAT), reaching to remote and poorly accessible areas, far away from the emission sources. Besides, most of SVOCs are lipophilic and bioaccumulative, which increase the risk to human exposure. According to the United States Environmental Protection Agency (US EPA), the category of SVOCs includes a large number of compounds such as polycyclic aromatic hydrocarbons (PAHs). PAHs are by-products of incomplete combustion or pyrolysis of fossil fuels and other organic materials such as wood and biomass and they can be issued by natural (e.g., volcanoes, forests fires, and grassland combustion) or anthropogenic sources. Although PAHs can be released by both sources, the anthropogenic origin have been identified as the main responsible of the PAHs presence in the environment, being the petrochemical industries an important emission sources of PAHs to air. Among the different PAHs, benzo(a)pyrene (BaP) has already been classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer (IARC) and is the only PAH with a legislated average limit in the atmosphere: 1 ng m-3 of BaP over 1 year. Furthermore, international studies suggest that the toxicity and environmental fate and transport of PAHs can be affected by the variations in the temperature and solar radiation associated with climate change, mainly in the most vulnerable regions, such as the Mediterranean basin.
In this thesis, atmospheric pollution due to the presence of PAHs and other SVOCs (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) as hexachlorobenzene (HCB), brominated flame retardants (BFRs) and synthetic musk fragrances (SMs)) has been assessed in Tarragona country Spain that is home to the one of the largest chemical/petrochemical industrial complex in Southern Europe.
The chapter 1 of this thesis was focused in to determine the monitoring approaches necessary for SVOCs environmental determination by means of passive sampling techniques. Among these techniques, passive air samplers with polyurethane foam (PUF-PAS) and lichen transplants were selected, since they are cheap, easy to deploy or to collect and allows the simultaneous sampling in remote and/or poorly accessible areas without available electric current and at different locations and/or scales.
PUF-PAS are worldwide used for air monitoring at global/regional scale, since have been the devices preferred by the United Nations Environment Program for global air monitoring. However, few international studies have been conducted in order to study the suitability of PUF-PAS for SVOCs (POPs) monitoring at a local scale. This chapter has confirmed that the use of PUF-PAS is fully viable for Tarragona county (local scale) sampling, since these devices have been able to capture different groups or families of SVOCs, such as PAHs, PCBs, BFRs, SMs and HCB, even at very low air concentrations (ng/m3), at different locations and involving low maintenance and costs. In addition, good correlations have been found between the PUF-PAS and lichens transplants when analyzing the environmental burden of PAHs, confirming the suitability of lichens as passive samplers. Regarding to SVOCs levels recorded by PUF-PAS and lichens transplants, it is observed that the area over the industrial influence (chemical and petrochemical areas) has higher concentrations of PAHs, PCBs and HCB than in urban areas and these are higher than in the background areas. On the other hand, SMs and BFR concentrations were lower than those and did not show significant differences between zones.
The chapter 2 of this thesis was aimed to improve analytical procedures for SVOCs determination using “green” alternatives. In last decades, several methods have been developed in order to detect, identify and quantify the chemicals released into the environment. Among these extraction and clean-up protocols are soxhlet, sonication, pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), microextraction techniques, solid-phase extraction (SPE), among others. In general, all these methods are effective but time and solvent consuming, and requiring expensive equipment, for this reason, a multi-residue method involving QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) coupled to GC-MS (Gas Chromatography–Mass Spectrometry) was validated for the simultaneous extraction of PAHs, PCBs, BFRs, SMs and HCB in soils and vegetation samples. The results showed that the QuEChERS methodology was a valid technique to make a screening of the compounds presents in a sample, either soil or vegetation, including those collected in Tarragona county. In addition, QuEChERS technique provided a considerable reduction in the amount of solvent and operating time, without compromising the performance of the method given by the validation parameters.
When the three passive sampling techniques, PUF-PAS, vegetation and soils were evaluated together some differences arise. PUF-PAS tend to capture the most volatile SVOCs, mainly associated with the gas phase. Vegetation traps the PAHs contents in the gas phase, but it also retains some of those sorbed to the particulate phase (which has not been washed by natural processes), while soils capture the heaviest and more resistant to degradation molecules, that could be associated with particulate phase. Concerning the monitoring time, the results obtained from PUF-PAS and ruderal vegetation (Piptatherum L.) versus soil showed that these matrices are able to provide information regarding the levels and sources of SVOCs at short- (2-3 months) and long-term, respectively.
Finally, the chapter 3 of this thesis was aimed to use the modelling approaches as a combined tools for monitoring PAHs in the environmental. The combination of monitoring and modelling tools is of high importance, being very valuable and complementary techniques. In this sense, monitoring is critical for models implementation and modelling helps predict the contaminants behavior in the environment, since they transform the valuable datasets into a complete understanding of spatial, temporal and chemical transport patterns. Likewise, models can identify the priority areas for sampling campaigns. In this thesis two different models, MUM-Fate (Multimedia Urban Model) and WRF+CHIMERE (Weather Research and Forecasting), were in order to predict PAHs fate, emissions and future concentrations considering actual and future climate conditions (RCP8.5 scenario, 2031-2050).
MUM-Fate model is a mass balance model based on the Level III steady-state fugacity of Mackay (1991), characterized by dividing the total study area into 7 different boxes or bulk media compartments. In the case of Tarragona county, MUM-Fate model provided a preliminary approximation of the PAHs distribution in the bulk media compartments defined for this area, by using simple approaches and calculations. Among the different compartments considered by this model, the organic film as the compartment with the highest concentrations of PAHs. However, and due the high losses in this compartment, the model positioned the soils and sediments as the greatest PAHs sinks in Tarragona County. Also this model was used to predict the emissions by backcalculations.
Regarding to WRF+CHIMERE model, is a kind of chemistry transport models (CTMs) that can complement the field data also considering the meteorology of the study area, the atmospheric chemistry processes and climate change, contributing to diminish the gaps still existing regarding SVOCs environmental behaviour. In this case, WRF+CHIMERE predictions indicate that in the future (2031-2050) concentrations of BaP will increase in air and decrease in soils in Tarragona county, resulting in an increase of 5x10-8 in the life-time risk of lung cancer, particularly in the most populated areas.
