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[1] The isotopic composition (d13C and D14C) of high\ud molecular weight dissolved organic carbon (HMW DOC)\ud was studied in the Tyne and Tweed estuaries, NE England.\ud Despite significant removal of terrigenous HMW DOC in\ud the low salinity regions (S < 15), D14C remained modern\ud with little variation around 115%. This lack of apparent age\ud discrimination was attributed to either non-oxidative\ud removal or the absence of a significant proportion of old\ud refractory C in the HMW DOC pool. At S < 15, we\ud observed seaward increases in d13C and D14C. With no\ud documented local 14C inputs, we attributed non-bomb\ud related 14C-enrichment at S < 15 to a possible ‘lingering\ud effect’ of distal anthropogenic sources in near-coastal North\ud Sea HMW DOC. Given the global distribution of potential\ud sources, we propose that anthropogenic 14C should be\ud considered in assigning ages of DOC pools in near-coastal\ud waters and suggest its possible use as a tracer for DOC\ud transformations.