Priority and emerging flame retardants in the aquatic environment: analytical development, occurrence and risk

Abstract

The presence of priority and emerging flame retardants (FR) in the environment deserve attention since many of these substances are toxic and persistent. The aim of this thesis was to evaluate the occurrence and impact of priority and emerging flame retardants in the aquatic environment. To accomplish this main objective, the present thesis involved the development of multiresidue methods for the analysis of different FR families in water, sediment, dust and sewage sludge and the application of developed methods for FR monitoring in rivers (UK and Spain) and wastewater treatment plants (WWTPs). Firstly, a multiresidue method based on gas chromatography (GC) coupled to quadrupole mass spectrometry (MS) was developed to determine organophosphorus flame retardants (OPFRs), polybrominated diphenyl ethers (PBDEs), new brominated flame retardants (NBFRs), bromophenols, bromoanilines, bromoanisoles and bromotoluenes. A comparison of two ionization techniques (electron ionization - EI, and electron capture negative ionization - ECNI) and two acquisition modes (selected ion monitoring – SIM, and selected reaction monitoring - SRM) revealed that GC-ECNI-MS/SIM presented the highest sensitivity at expenses of identification capacity, while GC-EI-MS/MS was the most selective technique, permitting the identification of target compounds at the pg levels. This last method was proposed for the determination of FRs in environmental samples. An extraction method for 8 PBDEs, 9 NBFRs and 10 OPFRs in river water and wastewater was developed based on solid phase extraction using Oasis HLB cartridges. In addition, a passive sampling method for monitoring of OPFRs and NBFRs in surface water was developed using the ceramic dosimeter device with HLB as receiving phase. The passive sampler was efficient for the monitoring of target compounds in river water for a deployment time of about 3 weeks, as evidenced by comparison of results obtained by passive and grab sampling. Furthermore, the extraction of target compounds in sediment, sewage sludge and dust was developed using ultrasound-assisted extraction with ethyl acetate/cyclohexane (5:2, v/v), clean-up with florisil cartridges and analysis by GC-EI-MS/MS. The method proved to be efficient and robust for analysis of target compounds in the studied matrices, as evidenced by the results obtained using spiked samples, a certificated reference material and by participating in an interlaboratory study.

Monitoring studies were performed at the River Aire (Yorkshire, UK) and at three Spanish rivers (Nalón, Arga and Besòs). In all cases, samples were collected in several points alongthe rivers, fromthe sourceto the mouth, and afterWWTP outputs, in order to identify themost important sourcesof FRs. In addition, influents, effluentsand sludge samples from five Spanish WWTPs were analyzed forevaluatingthe impact of WWTPs as a source ofFRto receiving waters. Among all FR studied, OPFRswerethe most ubiquitouscontaminants in surface waters, andWWTPeffluents wereindicated as the main source ofthese compounds.BDE-209 was themost abundantPBDEcongenerand was detected in water inthe River Aire (UK),in sediments fromthe River Besòs (Catalonia)and in sewage sludge.Low frequency of detection wasobserved for NBFRs in the studied riversand WWTPs.The minor presence of NBFR in the aquaticenvironment pointsto the impression thateither thesecompounds havenotbeen used in Spain or the UK or eitherthatthey have not been used long enough or atsufficient amounts to pose an environmental problem.A toxicity testperformed with Daphniamagnarevealed that OPFRs toxicity (EC50) waswell correlated with their lipophilicity (log Kow), that these compoundspresent similar mode of actionand thattheir joint effects are additive.This mean that joint toxicity of OPFRs at lowconcentrations can produce toxic effects in theaquatic organisms,andsomixturesof these contaminantsmust be considered in risk assessmentstudies. Finally, theriskassessment performed for the studied rivers indicated no risk associated to observedOPFR levels in waters. However, apotential risk foraquatic organismswas estimatedfor the River Aire (UK) associated tothehigh concentrationsof BDE-209 in water.

El objetivo de la presente tesis consistió en el desarrollo de métodos para el análisis multiresiduo de distintas familias de retardantes de llama en matrices ambientales, y su aplicación en estudios de vigilancia ambiental. Entre los diferentes métodos instrumentales desarrollados, el método basado en la cromatografía de gases acoplada a la espectrometría de masas en modo tándem (GC-EI-MS/MS) fue el más adecuado para el análisis de ocho éteres de polibromodifenilo (PBDEs), nueve nuevos retardantes de llama bromados (NBFRs) y diez retardantes de llama organofosforados (OPFRs) en las matrices ambientales propuestas en este estudio. Para el análisis de agua, se desarrolló un método basado en la extracción en fase sólida utilizando cartuchos HLB. Además, se desarrolló un método de muestreo pasivo para la determinación de cuatro OPFRs y dos NBFRs en agua de río utilizando un muestreador “ceramic dosimeter” y HLB como fase receptora. Para el análisis de sedimentos, lodos de depuradora y polvo, se desarrolló y validó un método utilizando la extracción líquido-sólido en un baño de ultrasonidos con acetato de etilo/ciclohexano (5:2, v/v), y purificación de los extractos con cartuchos florisil. El estudio de vigilancia ambiental incluyó la determinación de los compuestos objeto de estudio en 4 ríos de Inglaterra y España y cinco depuradoras en Catalunya. Se analizaron aguas y sedimentos de los ríos e influentes, efluentes y lodos de las depuradoras. Se observó que los OPFRs son los compuestos más ubicuos y más abundantes en todas las muestra ambientales, mientras el BDE-209 se detectó en los ríos y en los lodos de las depuradoras. Los demás PBDEs, y el DBDPE, HBB, PBEB, PBT, EHTBB, BTBPE y BEHTBP se detectaron con una menor frecuencia. Los estudios de toxicidad con Daphnia magna indicaron que mezclas de OPFRs poseen toxicidad aditiva. Se llevó a cabo la evaluación del riesgo para los distintos ríos estudiados y se observó que no hay un riesgo asociado con los niveles de los OPFRs presente en las aguas, pero se observó un riesgo asociado a la presencia del BDE-209 en las aguas del río Aire en Inglaterra.