Spatial and temporal variability of organochlorine compounds in wild mussels from Galician Rías (2010–2019)

Abstract

• PCBs and organochlorine pesticides were analyzed in wild mussels of Galician Rías. • Levels of many compounds presented significant relations with biological parameters. • PCA showed a clear difference between OCs levels from Rías Altas and Rías Baixas. • Rías Altas had the most polluted by OCs mussel samples. • Temporal trends of OCs showed a stabilisation to low levels. The objective of this work was to determine the spatial distribution and temporal trend (2010–2019) of organochlorine compounds (OCs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), in wild mussels from several Galician Rías (estuaries). Some of them, like the northernmost estuaries, were studied for the first time. OCs were determined by GC-ECD and confirmed by GC-MS/MS. SPCB levels (sum of PCBs 31, 28, 52, 101, 118, 153, 105, 138, 156, 180) were found in the range 7.2–263.1 ng/g dw (dry weight) and SDDt levels (sum of pp´- DDT, op´-DDT, pp´-DDE and pp´-DDD) in the range 2.5–18.8 ng/g dw. PCB levels were below European limits. Analysis of variance (ANOVA) showed some relationship between of OC levels and biological parameters (lipid content and condition index). Principal component analysis (PCA) reported a geographical characterization of Rías Altas and Rías Baixas and relationships between PCB congeners that revealed a similar pattern of entry. Legal restrictions on the production and use of PCBs and OCPs have led to a steady decline in OCs over the period under study (2010–2019).