PCDDS (DIOXINS) AND PCDFS (FURANS) IN SELECTED UK LAKE AND RESERVOIR SITES - CONCENTRATIONS AND TEQS IN SEDIMENT AND FISH SAMPLES

This paper describes a study that was designed to increase present kno wledge of the levels and behaviour of atmospherically derived PCDD/Fs in UK freshwaters. Sediment and fish samples were taken from four fres hwater locations where the main sources of PCDD/Fs were thought to be atmospheric. Total concentrations in sediments ranged from 500-5000 ng kg(-1) dry weight, and toxic equivalents (I-TEQs) between 5-100 ng kg (-1) dry weight. Sedimentary evidence was used to derive total inputs of PCDD/Fs to the lakes and from this it seems probable that two of th e sample sites receive inputs of PCDD/Fs largely from the atmosphere, and that the remaining two sites receive additional inputs from local or regional sources. PCDD/Fs were present in all fish samples taken, w ith total concentrations between 100-800 ng kg(-1) wet weight and TEQs between 1-20 ng kg(-1) wet weight. These values were consistent with those found in other international studies. Whilst results provide som e evidence for within-site similarities between different fish types, they did not suggest any similarities between the same species at diff erent sites. There was no evidence for a relationship between total PC DD/F concentrations in sediment and fish, although relationship betwee n 2378-substituted isomer levels in some sediment and fish samples was noted.