Resumen de Ecotoxicological risk of pollutants in iberian rivers
More than one-third of Earths available freshwater is used for anthropogenic purposes, which has led to its contamination by numerous chemical compounds. Their presence in the environment might have negative consequences for the environment and human health. In order to identify the compounds that might cause adverse effects in the ecosystems, ecotoxicological risk assessment is performed by comparing measured or predicted concentration of the compound in the environment with the threshold concentration of a certain effect. Due to the growing awareness of chemical risk in the environment, there is an increase of scientific literature on the subject. The aim of this thesis is to contribute to the growing scientific knowledge on the ecotoxicological risk of chemical compounds in the freshwater environment. Four rivers of Iberian Peninsula were used as case studies in this thesis; namely Llobregat, Ebro, Júcar, and Guadalquivir. The main drivers of risk for ecosystems in those rivers were identified and the evidence of effects caused by chemical compounds was provided. Prioritization schemes for freshwater organic pollutants were reviewed. Occurrence and risk of selected important pollutants in Europe and North America were compared. Pesticides and pyrene were identified as main risk driving compounds. Ranking index (RI), a new method for prioritization of pollutants is introduced. RI classifies the pollutants into three categories of concern on the basis of their ecotoxicological potential and distribution in the study area. By applying the RI to the dataset of more than 200 pollutants measured in the surface water of studied rivers, we identified that pesticides (e.g. organophosphate insecticides) and industrial organic compounds (i.e. alkylphenols) were of highest concern in the area, based on their toxicity to freshwater invertebrates and to a lesser extent to fish and algae. Emerging contaminants, such as pharmaceuticals (e.g. sertraline or losartan) or biocides (triclosan) were among the compounds classified in the second category of concern, due to their chronic risk. The site-specific risk of organic chemicals mixtures and metals was performed using concentration addition model (CA). It was found that mixtures of organic compounds and metals, posed an acute risk at 42% and 45% of total 77 sampling sites, respectively. The chronic risk was present at all sampling sites. The major drivers of acute and chronic risk were pesticides and metals. Pharmaceuticals, industrial compounds, and personal care were additional contributors to the chronic risk. The risk posed by the Water Framework Directive (WFD) priority pollutants (PP) was significant and those compounds were among the highest contributors to the risk. Banned pesticides and emerging contaminants significantly contributed to the risk. We used different macroinvertebrate based indicators to find the link between chemical pollution and ecosystems changes. A significant relationship between pesticides toxicity gradient and a decrease of SPEARindex, stressor-specific indicator for pesticide pollution was found. In We used the functional traits of macroinvertebrates to find the evidence of pesticides toxicity and urban-related multiple stressors in studied rivers. It was identified that multiple stressors were present at 50% of the sampling sites, mostly in urban areas. At urban sites, communities¿dominant traits were multivoltine indicating dominance of resilient taxa and deposit feeding, which could be associated with the taxa resistant to hydrological disturbances or presence of nutrients. In contrast, at pesticide impacted sites taxa with high levels of egg protection was dominant, indicating a higher risk for egg mortality at those sites, potentially due to pesticides. The functional diversity of assemblages at urban sites was low, suggesting the functional homogenization of assemblages in urban areas, which might increase the sensitivity of ecosystems.
