Investigación
In recent years, our research group has focused its studies on the environmental concern of the so-called contaminants of emerging concern (CECs) such as nanomaterials, pharmaceuticals, pesticides, industrial chemicals, surfactants, personal care products and plastic particles. While their presence in the environment is not necessarily new, there is absence of regulation or harmonized information on levels and effects in ecosystems. These contaminants are consistently found in soils and aquatic environments as well as in sewage sludge and reclaimed water (RW) from wastewater treatment plants (WWTPs) due to the limited capacity of conventional wastewater treatments to remove CECs.
The Laboratory of Ecotoxicology aims to evaluate the effects of CECs -singly or as mixtures- on the terrestrial and aquatic compartments using
in vitro (cell lines) and
in vivo (i.e. plants, invertebrates and vertebrates) experimental biological models representative of both environments. The simultaneous presence of two or more of these CECs can result in synergistic or antagonistic effects thus modifying their individual toxicity and environmental behavior. Our group also focuses on the potential transference of these contaminants from soil to water and vice versa, as well as from a particular medium (i.e. soil or water) to organisms (i.e. terrestrial or aquatic, respectively).
Following are the core results of our different research projects underway:
Our group has evaluated the ecotoxicological and toxicological safety of the
reclaimed water (RW) reuse for crop irrigation and aquaculture. RW samples were collected in different seasons of the year from WWTPs located in different areas of Spain. Results from our laboratory-scale experiments suggested minor differences in the concentrations of CECs in the RWs from the different tertiary treatments. The laboratory bioassays with aquatic organisms (i.e. algae -Chlorella vulgaris-, invertebrates -Daphnia magna, Physa acuta, Chyronomus riparius-, vertebrates -Oryzias latipes and
Xenophus laevis-) showed effects on growth, ingestion and reproduction, and suggested thyroid disruption. While some RW samples suggested concentration-response related effects, most ecotoxicological data revealed inconsistent results in the observed effects. These results substantiated the high heterogeneity and of the RW samples. The semi-field bioassays with plants concluded that the adsorption of CECs to the roots and their bioaccumulation in the organs depended on a complex combination of factors including the physico-chemical properties of the CECs (i.e. hydrophobicity, solubility and ionic form), the soil properties (i.e. content and characteristics of organic matter), and the physiological properties of each plant species (i.e. lipid content, metabolism, growth and transpiration rates).These proved to be key parameters for generating exposure scenarios to assess the risk of human exposure due to consumption of crops irrigated with RW. Additional studies with freshwater organisms and three crop plants models were carried in which
surfactants were added to RW or to pure CECs. Overall, results suggested a modification of the bioavailability of CECs such as carbamazepine or triclosan, thus increasing their environmental risk. However, no toxicity increase was seen for atenolol.
Additional research works have also been carried that evaluated the effects of nanomaterials present in agricultural soils as a result of their application as fertilizer or from soil amendments. Results concluded that the effects of
zinc oxide in nanoparticle size (ZnO NP) in soil organisms depended on the characteristics of both, the soil and the biological species. Acidic soils increased zinc bioavailability to organisms and hence the toxic effects were more pronounced. In plants the ZnO NP reduced seed germination, decreased the biomass production, and increased the response in biomarkers related to oxidative stress and cell damage (cytotoxicity). However, these effects were only observed at high doses and were comparable to those produced by other zinc compounds used in agriculture. Invertebrates (earthworms) were more sensitive with low doses resulting in severe effects on reproduction. Our studies revealed different response of soil microorganisms according to the measured parameter.
Our research in this area was also extended to evaluate
the combined presence of ZnO NP with other contaminants, e.g chlorpyrifos. Results revealed modified ZnO NP and chlorpyrifos toxicity due to co-exposure. Environmental concern arises as, even if applied individually, there is the potential that ZnO NP will reach agricultural soils previously containing other chemicals. Hence the co-exposure of soil organisms and crops to these contaminants will occur.
