Phthalates and Nonylphenols in Roskilde Fjord

NPDE and DEHP in the Hove Å system as bar graphs for the samplingpositions in the flow direction (East to West).30002500NP NPDE DEHPConcentration, ng/g dm200015001000Flow5000Hove Åupstr.Lake G.100 m WLake G.200 m WLake G.S bankHove Ådowns.Figure 30 Mean and standard deviation of most abundant substances in sedimentalong the flow direction of Hove Å system.As noted from Figure 30, DEHP follows a monotonously increasing tendencyin the flow direction, with the exception of the South bank, inwhich very low amounts of all substances occur. This is probably due tothe sandy character of the bottom at that position, in contrast to the organiccharacter at the two other lake positions. The difference may bedue to the action of waves near the bank. Furthermore, assuming themain input to the lake is through Hove Å, the main sedimentation shouldoccur in the line connecting the inlet and outlet in the lake, which is adistance to the North of the South bank. Remarkably, the tendency forNP and NPDE is strongly increasing until the 200 m position in the lake,followed by much lower amounts downstream. The same tendency isseen for DBP and BBP in Table 18.The same trend for these substances was found in the water. An interpretationof these observations would be that the main sedimentationprocess of all substances occurs at the 200m position in the lake, wherethe lake is broad and deepest and the water velocity low. Hence, the substancesare depleted downstream the lake, occurring in considerablylower concentrations in water as well as sediment. DEHP, however, deviatesfrom this pattern, since larger amounts are found downstream.Probably new sources downstream the lake are present.5.3.3 Correlation analysis of streams and lakeIn Table 19 the significant correlations between substances in all lakeand stream water samples are shown (N=19, r crit. = 0.53, p < 0.01). Itappears that the higher phthalates from BBP and up are correlated withDEHP. The same correlations are found in the fjord water, but for that51