Organochlorine compounds and polycyclic aromatic hydrocarbons in mussels from Ria de Vigo (the Northern Spanish coast). Current levels and long-term trends (2010-2019). Relationship with human pressures

OCs (organochlorine compounds), such as PCBs (polychlorinated biphenyls) and OCPs (organochlorine pesticides), and PAHs (polycyclic aromatic hydrocarbons) were determined in wild and raft mussels collected in several stations from Ria de Vigo during the period 2010-2019. The concentration levels of Sigma PCBs Sigma DDs (sum of pp'-DDE and pp'-DDD metabolites) and Sigma PAHs ranged from 22.1, 2.63 and 7.55 ng g(-1) to 58.0, 6.89 and 25.2 ng g(-1) dry weight, respectively. The concentrations of isomers of PCBs in mussel were in the order hexachlorobiphenyls > pentachlorobiphenyls > tetrachlorobiphenyls > trichlorobiphenyls. PCBs 153 and 138 were the most abundant in all samples. Pp'-DDE was the predominant metabolite (70.8% of Sigma DDs). The main PAHs in decreasing order of abundance were CHR > BbF > BaA > IcdP. Three biological parameters: lipid content, shell length and condition index have also been investigated. Univariate techniques confirmed that levels of many compounds presented significant relation (p<0.05) with two of the biological parameters (shell length and condition index). In the case of lipid content, only PCB180 congener was significantly related. Multivariate techniques of data exploration such as Principal Component Analysis (PCA) showed that spatial distribution of PCBs, OCPs and PAHs levels appeared in the studied samples and was justified by local human pressures. Temporal trends (linear regressions) showed a decrease, mainly of OCs levels, along the period 2010-2019. (C) 2021 Elsevier B.V. All rights reserved.