AbstractThis comprehensive study focused on the spatial and seasonal variation of organophosphorus flame retardants and plasticizers (OPs) in surface water from the estuary of the River Elbe and the German Bight (North Sea). 100 surface water samples were extracted by solid phase extraction (SPE) and analyzed by gas chromatography-mass spectrometry (GC-MS) with regard to 16 different OPs. The dominating substance was found to be tris(1-chloro-2-propyl) phosphate (TCPP) (Elbe: 40 – 250 ng L−1, German Bight: 3 – 28 ng L−1). Furthermore, triethyl phosphate (TEP), tri-iso-butyl phosphate (TiBP), tris(2-butoxyethyl) phosphate (TBEP), and triphenylphosphine oxide (TPPO) were detected in concentrations up to 180 ng L−1. Seasonal trends were detected for the longitudinal profile of the Elbe estuary. Besides the dilution of river water with North Sea water towards the mouth, leading to decreasing concentrations at the four sampling cruises (March, May, August, and October, 2010), an additional depletion of non-halogenated OPs was observed in summer which is supposed to be due to biodegradation or photodegradation.