CHROMIUM REMOVAL IN CONSTRUCTED WETLANDS AND PHYSIOLOGICAL RESPONSE OF EMERGENT MACROPHYTES FROM ARGENTINA

DANIELA SILVINA ARAN; CARLOS HARGUINTEGUY; MAGDALENA MONFERRAN; FERNANDEZ-CIRELLI A; MARÍA LUISA PIGNATA

Ghent

Congreso; 8th Young Environmental Scientists Meeting; 2019

Introduction Leather tanning generates liquid effluents with highcontents of organic matter, sulfides and trivalent chromium. Thedischarge of these untreated effluents in aquatic environmentsgenerate serious problems with ecological risks. The use ofconstructed wetlands is considered a reliable technology for thetreatment of wastewater with metals, and aquatic plants have afundamental role in these systems. Schoenoplectus californicus,Juncus effusus and Eleocharis palustris are native aquatic plants,of interest for their use in the phytoextraction of Cr. Thesemacrophytes are perennial, rooted, rhizomatous and are part of theemergent vegetation in many lakes and estuarine areas of theArgentine Republic. Experimental work was developed to testthe hypothesis that the aquatic species Schoenoplectus californicus,Juncus effusus and Eleocharis palustris are resistant to chromiumexposure and can accumulate this metal in the root. MethodologySchoenoplectus californicus, Juncus effusus and Eleocharispalustris were exposed for four weeks to increasing concentrationsof Cr (Control treatment T0: 0 mg L-1, Treatment T1: 1 mg L-1,Treatment T2: 10 mg L-1) in constructed wetlands. The indicatorsof physiological damage that were analyzed were parameters of thephotosynthetic system (chlorophyll, pheophytin, carotenoids), andalso indicators of oxidative stress in stem and root, such asconjugated hydroperoxydienes and malondialdehyde. In addition,the removal of Cr from the solution and the accumulation of themetal in the root and stem were measured. Results andinterpretation The macrophytes Schoenoplectus californicus,Juncus effusus and Eleocharis palustris exposed to increasingconcentrations of Cr showed to be tolerant to the metal and not toaffect the photosynthetic system. The removal of the metal fromthe solution was 99% in all cases and the largest accumulation ofthe metal occurred at the base of the stem and the root of theplants. Taking into account the tolerance of the macrophytes S.californicus, J. effusus and E. palustris at increasing concentrationsof Cr, it could be determined that they are plants of interest fortheir use in phytoremediation of water contaminated withchromium.P02Toxicokinetics of imidacloprid in mayflies: a study on thedegradation and biotransformation of imidaclopridA. Huang, Wageningen University and Research; N. van denBrink, Wageningen University / Dept of Toxicology; I. Roessink,Wageningen University and Research / Department of AquaticEcology and Water Quality Management; P. van den Brink,Wageningen Environmental Research / Department of AquaticEcology and Water Quality Management&WageningenEnvironmental Research1.Introduction Neonicotinoids (NNIs) belong to the group ofnitroguanidine systemic insecticides, which induced increasedenvironmental concerns recently, based on their potential risks tothe aquatic system. Currently, the EU bans the outdoor use ofimidacloprid (IMI), clothianidin and thiamethoxam. However, thedegradation products and metabolites of NNIs are hardly studied,especially for the aquatic organism, which may hamper theenvironmental risk assessment of NNIs. To fill this knowledge gap,we will study the toxicity of IMI and its metabolites to aquaticorganisms, which is the most used chemical among NNIs. Themayfly, which is found to be one of the most sensitive species andalso the essential freshwater invertebrate, is chosen as the focalspecies. During upcoming experiments, the uptake kinetics of IMIand metabolites into the mayfly will be quantified and the toxicityof the parent and its metabolites will be explored. Our results willprovide a further mechanistic understanding of the toxicokineticsof IMI and its metabolites in mayflies. 2.Methodology To answerthe question of whether IMI is degraded or metabolised bymayflies, a 4-day toxicity study will be conducted with IMI and itsmetabolites. 10 individuals of mayflies will be put in a 1L beakerwhich contains different concentrations of either olefin-IMI, ureaIMI, 6-CNA, 5-OH-IMI or IMI . The mortality will be scored onday 1, 2, 3 and 4 and the remaining organism, as well as the water,will be sampling at 4d. The mayflies will be captured,homogenised, extracted with acetonitrile and further analysed byLiquid Chromatography-Tandem Mass Spectrometry for IMI andits metabolites. The water will also be extracted by liquid-liquidextraction, and also evaluated on residues of IMI and itsmetabolites. 3.Expected results The current study will (1) show thetoxicity of the metabolites to mayflies, indicating whethermetabolites are of importance for future risk assessment of IMI, (2)assess concentrations of IMI and its metabolites in the body of themayflies, (3) show whether the degradation products of IMI inwater are different from the metabolites found in the mayflies. Inour hypothesis, whether IMI is metabolised or degraded to toxicmetabolites by mayflies, such metabolism might explain their highsensitivity, in comparison to, for instance, Daphnia.P03Attractive and aversive responses of zebrafish larvae tofrequently detected classes of insecticidesS. Könemann, Eawag - Swiss federal Institute of Aquatic Scienceand Technology / Environmental Toxicology; U. Herget, Caltech,California Institute of Technology, 1200 E. California Blvd.,Pasadena; C.M. vom Berg, Eawag - Swiss federal Institute ofAquatic Science and Technology / Environmental ToxicologySelecting appropriate behavioural responses is crucial for thesurvival of single organisms as well as the whole population. Suchbehavioural responses are based on sensing and processingenvironmental stimuli. Organisms possess an innate ability toescape from threatening situations they are exposed to. Suchsituations can be posed by unfavourable environmental conditions,predators or alarm substances. Similarly, they are attracted tofavourable cues such as food sources or mating partners. As mostinsecticides are designed to interfere with neuronal signalling, theyare able to adversely affect this ability to process sensory input andreact appropriately to environmental stimuli with extensiv