INFLUENCE OF CARRIER AND BACTERICIDE ON SORPTION COEFFICIENTS OF HYDROPHOBIC ORGANIC-COMPOUNDS FOR 2 LAKE-SEDIMENTS

Sorption coefficients of a series of hydrophobic organic compounds wer e determined for two sediments, one with a high (RDD sediment) and one with a low organic carbon content (OVP sediment). The chemicals were administered to water using a generator column, or using one of the fo llowing carriers (0.5%, v/v): acetone, methanol or propanol. In additi on to the influence of the mode of administration, the influence of th e bactericide, sodium azide (NaN3), on the sorption coefficients was s tudied. For most compounds, higher sorption coefficients were found in RDD sediment than in OVP sediment. Only for the most hydrophobic comp ounds no large differences were found between the sorption coefficient s in the two sediments. In RDD sediment, the use of the carriers showe d lower sorption coefficients for almost all compounds, and in OVP sed iment the use of the carrier showed only for some of the more hydropho bic compounds lower sorption coefficients, than the use of the generat or column. The highest dry weight (DW) and total organic carbon (TOC) concentrations were found in the aqueous phase of the high organic car bon sediment (RDD). In addition, methanol and propanol resulted in sig nificant increases in TOC concentrations. The influence of DW and TOC concentrations on the sorption coefficients could, however, not be qua ntified. Since carriers may have a significant effect on the experimen tal determination of sorption coefficients, we suggest to use the gene rator column for administering the compounds, in combination with a ba ctericide to prevent bacterial activity. (C) 1998 Elsevier Science Ltd . All rights reserved.