Phthalates and organophosphate esters in surface water, sediments and zooplankton of the NW Mediterranean Sea: Exploring links with microplastic abundance and accumulation in the marine food web

In this study, surface seawater, sediment and zooplankton samples were collected from three different sampling stations in Marseille Bay (NW Mediterranean Sea) and were analyzed for both microplastics and organic plastic additives including seven phthalates (PAEs) and nine organophosphate esters (OPEs). PAE concentrations ranged from 100 to 527 ng L⁻¹ (mean 191 ± 123 ng L⁻¹) in seawater, 12–610 ng g⁻¹ dw (mean 194 ± 193 ng g⁻¹ dw) in sediment and 0.9–47 μg g⁻¹ dw (mean 7.2 ± 10 μg g⁻¹ dw) in zooplankton, whereas OPE concentrations varied between 9 and 1013 ng L⁻¹ (mean 243 ± 327 ng L⁻¹) in seawater, 13–49 ng g⁻¹ dw (mean 25 ± 11 ng g⁻¹ dw) in sediment and 0.4–4.6 μg g⁻¹ dw (mean 1.6 ± 1.0 μg g⁻¹ dw) in zooplankton. Microplastic counts in seawater ranged from 0 to 0.3 items m⁻³ (mean 0.05 ± 0.05 items m⁻³). We observed high fluctuations in contaminant concentrations in zooplankton between different sampling events. However, the smallest zooplankton size class generally exhibited the highest PAE and OPE concentrations. Field-derived bioconcentration factors (BCFs) showed that certain compounds are prone to bioaccumulate in zooplankton, including some of the most widely used chlorinated OPEs, but with different intensity depending on the zooplankton size-class. The concentration of plastic additives in surface waters and the abundance of microplastic particles were not correlated, implying that they are not necessarily good indicators for each other in this compartment. This is the first comprehensive study on the occurrence and temporal variability of PAEs and OPEs in the coastal Mediterranean based on the parallel collection of water, sediment and differently sized zooplankton samples.