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Pete Smith - One of the best experts on this subject based on the ideXlab platform.

  • Spatial distribution of Oxytetracycline and elevated frequencies of Oxytetracycline resistance in sediments beneath a marine salmon farm following Oxytetracycline therapy
    Aquaculture, 1996
    Co-Authors: Joseph P. Kerry, Maura Hiney, Rosie Coyne, Deirdre Gilroy, Pete Smith
    Abstract:

    Abstract The concentrations of Oxytetracycline and the frequencies of Oxytetracycline resistant microorganisms were determined in 11 samples taken from the sediments in the vicinity of a block of fish cages at a marine salmon farm. The cage block contained 10 tonnes of Atlantic salmon smolts and a total of 20 kg of Oxytetracycline were administered during the 12 day treatment. Samples cores were collected by divers 5 days after the end of the period of therapy and the top 2 cm of each core was analysed. HPLC analysis was able to quantify the Oxytetracycline concentrations in three of the six samples taken directly under the cage block. The mean concentration under the cage was between 0.65 and 1.2 μg g −1 ( n = 6) depending on the values attributed to samples where the concentrations were below the level of quantitation (1.2 μg g −1 ). In the five samples taken from locations not directly under the cage block Oxytetracycline was only detected in the sample taken adjacent to, and down current from, the cage block. This sample was collected 10 m to the west of the cage block and contained 4.2 μg g −1 Oxytetracycline. These data indicate that Oxytetracycline was confined to an area of the sediment which was smaller in extent than the area of the cage block itself. The frequencies of resistance to Oxytetracycline in the microflora cultured from the samples were determined by differential plating on 2216V media, containing 25 and 100 μg ml −1 Oxytetracycline. Analysis of eighty three samples from sites free of overt human influence demonstrated that the background levels of resistance at these two selection concentrations were 1.3 ± 1.3% and 0.4 ± 0.6%, respectively. Elevated frequencies of resistance were detected in samples from a wider area than the cage block. The median frequency of resistance in the samples ( n = 6) taken from directly under the cage block was 1.4% at 100 μg ml −1 and 5.3% at 25 μg ml −1 . In the samples ( n = 5) taken from outside the cage block the frequencies were 5.3% at 100 μg ml −1 and 8.5% at 25 μg ml −1 . There was no correlation between the concentration of Oxytetracycline in a sample and the frequency of resistance that was determined in the culturable microflora in that sample.

  • Fate of Oxytetracycline in a fresh water fish farm: influence of effluent treatment systems
    Aquaculture, 1994
    Co-Authors: Pete Smith, John Donlon, Rosie Coyne, David J. Cazabon
    Abstract:

    Abstract The fate of orally administered Oxytetracycline in a fresh-water hatchery was investigated using high-performance liquid chromatography. A filter of nominal porosity 50 μm in the farm effluent was capable of at least a 500–650-fold concentration of the Oxytetracycline into the filter retentate flow. No Oxytetracycline was detected in the filtered farm effluent (limit of detection 0.02 μg·ml−1). Analysis of hourly samples of the retentate taken over a 24-hour period allowed an estimate of the daily amount of Oxytetracycline retained by the filter. This estimate (1250 g) was of the same order as the amount of Oxytetracycline used on the farm (904 g on the day of sampling and 1104 g on the preceding day). Thus the quasi-totality of the input Oxytetracycline was removed from the farm effluent by the filter. A sedimentation trap on the filter retentate flow removed Oxytetracycline from this flow at a variable and lower (12–92%) efficiency. It is argued that correct design of effluent treatment systems could significantly reduce the environmental impact of land-based fish farms.

  • Concentration and persistence of Oxytetracycline in sediments under a marine salmon farm
    Aquaculture, 1994
    Co-Authors: Rosie Coyne, Maura Hiney, Brendan O'connor, Joe Kerry, Dave Cazabon, Pete Smith
    Abstract:

    Abstract The concentration of Oxytetracycline in the sediment under two adjacent cage blocks in a marine salmon farm was determined following the therapeutic use of the drug. The sediment cores were grey, indicating some build-up of organic material. Infaunal polychaetes were present as were mobile fauna including crabs, starfish and flat fish. There were no significant accumulations of undigested feed pellets under the cages. At one block where 186 kg Oxytetracycline was used over 10 days the Oxytetracycline concentrations were determined under a single cage that received 8.65 kg Oxytetracycline during the treatment. Peak concentrations in the top 2 cm of the sediment were 9.9±2.9 μg·g −1 . This declined at an exponential rate ( r 2 =0.99) with a half-life of 16 days. At the second block the Oxytetracycline concentration was measured with a sampling programme designed to determine the horizontal and vertical distribution of Oxytetracycline under the whole cage block during and after a treatment where 175 kg of Oxytetracycline were used over 12 days. Peak concentrations, in the top 2 cm of the sediments under the cage block, were 10.9±6.5 μg·g −1 and this declined at an exponential rate ( r 2 =0.99) with a half-life of 13 days. Nineteen days after the end of the therapy Oxytetracycline was detected at depths of up to 8 cm in the sediment, but the concentration of the antibacterial agent had decreased at all levels in the sediment 14 days later. At the end of the treatment Oxytetracycline was detected in an area of the sediment less than twice the area of the cages themselves. Data on current flow and sedimentation rate were used to generate a predictive model of the area of sediment that would be subject to the deposition of both pelleted fish feed and fish faeces. Oxytetracycline was confined to the area of sediment predicted to be subject to feed deposition that was directly under and slightly to the west of the cage block. Oxytetracycline was not detected in the area predicted to be subject to faecal deposition only.

  • Frequency and distribution of resistance to Oxytetracycline in micro-organisms isolated from marine fish farm sediments following therapeutic use of Oxytetracycline
    Aquaculture, 1994
    Co-Authors: Joe Kerry, Rosie Coyne, Maura Hiney, Dave Cazabon, Saoirse Nicgabhainn, Pete Smith
    Abstract:

    Abstract the background level of resistance to Oxytetracycline in sediments free of anthrogogenic influences was determined on 2216 V agar with 25 μg·g −1 Oxytetracycline. The mean frequency of resistance in 153 samples taken in Galway Bay was 1.2 ±1.8%. The impact of Oxytetracycline therapy on the frequency of resistance in the sediments under a marine fish farm was investigated on two occasions. In the first investigation, Oxytetracycline was detected at a concentration of 9.9 ± 2.9 μg·g −1 in the sediments under a cage that received 865 g Oxytetracycline per day for 10 days, but no significant rise in resistance frequency was detected. In the second investigation, Oxytetracycline was detected at a concentration of 10.9 ± 6.5 μg·g −1 in the sediments under a cage block that received 175 kg Oxytetracycline over 12 days. The frequency of resistance reached 16.0 ± 8.9% after the treatment. The frequency declined at an exponential rate ( r 2 =0.89) with a half-life of 26 days. At 73 days after the end of therapy the frequency, in under-cage samples, was not significantly higher than the background level. At the end of the therapy elevated frequencies of resistance were detected up to 75 m from the edge of the cage block and in samples where the levels of Oxytetracycline were below the limit of detection (1.2 μg·g −1 ). Thirty-three days after the end of the therapy the frequency of resistance in all samples not directly under the cages was not significantly higher than in samples taken from sediments free of anthropogenic influence.

Rosie Coyne - One of the best experts on this subject based on the ideXlab platform.

  • Spatial distribution of Oxytetracycline and elevated frequencies of Oxytetracycline resistance in sediments beneath a marine salmon farm following Oxytetracycline therapy
    Aquaculture, 1996
    Co-Authors: Joseph P. Kerry, Maura Hiney, Rosie Coyne, Deirdre Gilroy, Pete Smith
    Abstract:

    Abstract The concentrations of Oxytetracycline and the frequencies of Oxytetracycline resistant microorganisms were determined in 11 samples taken from the sediments in the vicinity of a block of fish cages at a marine salmon farm. The cage block contained 10 tonnes of Atlantic salmon smolts and a total of 20 kg of Oxytetracycline were administered during the 12 day treatment. Samples cores were collected by divers 5 days after the end of the period of therapy and the top 2 cm of each core was analysed. HPLC analysis was able to quantify the Oxytetracycline concentrations in three of the six samples taken directly under the cage block. The mean concentration under the cage was between 0.65 and 1.2 μg g −1 ( n = 6) depending on the values attributed to samples where the concentrations were below the level of quantitation (1.2 μg g −1 ). In the five samples taken from locations not directly under the cage block Oxytetracycline was only detected in the sample taken adjacent to, and down current from, the cage block. This sample was collected 10 m to the west of the cage block and contained 4.2 μg g −1 Oxytetracycline. These data indicate that Oxytetracycline was confined to an area of the sediment which was smaller in extent than the area of the cage block itself. The frequencies of resistance to Oxytetracycline in the microflora cultured from the samples were determined by differential plating on 2216V media, containing 25 and 100 μg ml −1 Oxytetracycline. Analysis of eighty three samples from sites free of overt human influence demonstrated that the background levels of resistance at these two selection concentrations were 1.3 ± 1.3% and 0.4 ± 0.6%, respectively. Elevated frequencies of resistance were detected in samples from a wider area than the cage block. The median frequency of resistance in the samples ( n = 6) taken from directly under the cage block was 1.4% at 100 μg ml −1 and 5.3% at 25 μg ml −1 . In the samples ( n = 5) taken from outside the cage block the frequencies were 5.3% at 100 μg ml −1 and 8.5% at 25 μg ml −1 . There was no correlation between the concentration of Oxytetracycline in a sample and the frequency of resistance that was determined in the culturable microflora in that sample.

  • Fate of Oxytetracycline in a fresh water fish farm: influence of effluent treatment systems
    Aquaculture, 1994
    Co-Authors: Pete Smith, John Donlon, Rosie Coyne, David J. Cazabon
    Abstract:

    Abstract The fate of orally administered Oxytetracycline in a fresh-water hatchery was investigated using high-performance liquid chromatography. A filter of nominal porosity 50 μm in the farm effluent was capable of at least a 500–650-fold concentration of the Oxytetracycline into the filter retentate flow. No Oxytetracycline was detected in the filtered farm effluent (limit of detection 0.02 μg·ml−1). Analysis of hourly samples of the retentate taken over a 24-hour period allowed an estimate of the daily amount of Oxytetracycline retained by the filter. This estimate (1250 g) was of the same order as the amount of Oxytetracycline used on the farm (904 g on the day of sampling and 1104 g on the preceding day). Thus the quasi-totality of the input Oxytetracycline was removed from the farm effluent by the filter. A sedimentation trap on the filter retentate flow removed Oxytetracycline from this flow at a variable and lower (12–92%) efficiency. It is argued that correct design of effluent treatment systems could significantly reduce the environmental impact of land-based fish farms.

  • Concentration and persistence of Oxytetracycline in sediments under a marine salmon farm
    Aquaculture, 1994
    Co-Authors: Rosie Coyne, Maura Hiney, Brendan O'connor, Joe Kerry, Dave Cazabon, Pete Smith
    Abstract:

    Abstract The concentration of Oxytetracycline in the sediment under two adjacent cage blocks in a marine salmon farm was determined following the therapeutic use of the drug. The sediment cores were grey, indicating some build-up of organic material. Infaunal polychaetes were present as were mobile fauna including crabs, starfish and flat fish. There were no significant accumulations of undigested feed pellets under the cages. At one block where 186 kg Oxytetracycline was used over 10 days the Oxytetracycline concentrations were determined under a single cage that received 8.65 kg Oxytetracycline during the treatment. Peak concentrations in the top 2 cm of the sediment were 9.9±2.9 μg·g −1 . This declined at an exponential rate ( r 2 =0.99) with a half-life of 16 days. At the second block the Oxytetracycline concentration was measured with a sampling programme designed to determine the horizontal and vertical distribution of Oxytetracycline under the whole cage block during and after a treatment where 175 kg of Oxytetracycline were used over 12 days. Peak concentrations, in the top 2 cm of the sediments under the cage block, were 10.9±6.5 μg·g −1 and this declined at an exponential rate ( r 2 =0.99) with a half-life of 13 days. Nineteen days after the end of the therapy Oxytetracycline was detected at depths of up to 8 cm in the sediment, but the concentration of the antibacterial agent had decreased at all levels in the sediment 14 days later. At the end of the treatment Oxytetracycline was detected in an area of the sediment less than twice the area of the cages themselves. Data on current flow and sedimentation rate were used to generate a predictive model of the area of sediment that would be subject to the deposition of both pelleted fish feed and fish faeces. Oxytetracycline was confined to the area of sediment predicted to be subject to feed deposition that was directly under and slightly to the west of the cage block. Oxytetracycline was not detected in the area predicted to be subject to faecal deposition only.

  • Frequency and distribution of resistance to Oxytetracycline in micro-organisms isolated from marine fish farm sediments following therapeutic use of Oxytetracycline
    Aquaculture, 1994
    Co-Authors: Joe Kerry, Rosie Coyne, Maura Hiney, Dave Cazabon, Saoirse Nicgabhainn, Pete Smith
    Abstract:

    Abstract the background level of resistance to Oxytetracycline in sediments free of anthrogogenic influences was determined on 2216 V agar with 25 μg·g −1 Oxytetracycline. The mean frequency of resistance in 153 samples taken in Galway Bay was 1.2 ±1.8%. The impact of Oxytetracycline therapy on the frequency of resistance in the sediments under a marine fish farm was investigated on two occasions. In the first investigation, Oxytetracycline was detected at a concentration of 9.9 ± 2.9 μg·g −1 in the sediments under a cage that received 865 g Oxytetracycline per day for 10 days, but no significant rise in resistance frequency was detected. In the second investigation, Oxytetracycline was detected at a concentration of 10.9 ± 6.5 μg·g −1 in the sediments under a cage block that received 175 kg Oxytetracycline over 12 days. The frequency of resistance reached 16.0 ± 8.9% after the treatment. The frequency declined at an exponential rate ( r 2 =0.89) with a half-life of 26 days. At 73 days after the end of therapy the frequency, in under-cage samples, was not significantly higher than the background level. At the end of the therapy elevated frequencies of resistance were detected up to 75 m from the edge of the cage block and in samples where the levels of Oxytetracycline were below the limit of detection (1.2 μg·g −1 ). Thirty-three days after the end of the therapy the frequency of resistance in all samples not directly under the cages was not significantly higher than in samples taken from sediments free of anthropogenic influence.

Maura Hiney - One of the best experts on this subject based on the ideXlab platform.

  • Spatial distribution of Oxytetracycline and elevated frequencies of Oxytetracycline resistance in sediments beneath a marine salmon farm following Oxytetracycline therapy
    Aquaculture, 1996
    Co-Authors: Joseph P. Kerry, Maura Hiney, Rosie Coyne, Deirdre Gilroy, Pete Smith
    Abstract:

    Abstract The concentrations of Oxytetracycline and the frequencies of Oxytetracycline resistant microorganisms were determined in 11 samples taken from the sediments in the vicinity of a block of fish cages at a marine salmon farm. The cage block contained 10 tonnes of Atlantic salmon smolts and a total of 20 kg of Oxytetracycline were administered during the 12 day treatment. Samples cores were collected by divers 5 days after the end of the period of therapy and the top 2 cm of each core was analysed. HPLC analysis was able to quantify the Oxytetracycline concentrations in three of the six samples taken directly under the cage block. The mean concentration under the cage was between 0.65 and 1.2 μg g −1 ( n = 6) depending on the values attributed to samples where the concentrations were below the level of quantitation (1.2 μg g −1 ). In the five samples taken from locations not directly under the cage block Oxytetracycline was only detected in the sample taken adjacent to, and down current from, the cage block. This sample was collected 10 m to the west of the cage block and contained 4.2 μg g −1 Oxytetracycline. These data indicate that Oxytetracycline was confined to an area of the sediment which was smaller in extent than the area of the cage block itself. The frequencies of resistance to Oxytetracycline in the microflora cultured from the samples were determined by differential plating on 2216V media, containing 25 and 100 μg ml −1 Oxytetracycline. Analysis of eighty three samples from sites free of overt human influence demonstrated that the background levels of resistance at these two selection concentrations were 1.3 ± 1.3% and 0.4 ± 0.6%, respectively. Elevated frequencies of resistance were detected in samples from a wider area than the cage block. The median frequency of resistance in the samples ( n = 6) taken from directly under the cage block was 1.4% at 100 μg ml −1 and 5.3% at 25 μg ml −1 . In the samples ( n = 5) taken from outside the cage block the frequencies were 5.3% at 100 μg ml −1 and 8.5% at 25 μg ml −1 . There was no correlation between the concentration of Oxytetracycline in a sample and the frequency of resistance that was determined in the culturable microflora in that sample.

  • Concentration and persistence of Oxytetracycline in sediments under a marine salmon farm
    Aquaculture, 1994
    Co-Authors: Rosie Coyne, Maura Hiney, Brendan O'connor, Joe Kerry, Dave Cazabon, Pete Smith
    Abstract:

    Abstract The concentration of Oxytetracycline in the sediment under two adjacent cage blocks in a marine salmon farm was determined following the therapeutic use of the drug. The sediment cores were grey, indicating some build-up of organic material. Infaunal polychaetes were present as were mobile fauna including crabs, starfish and flat fish. There were no significant accumulations of undigested feed pellets under the cages. At one block where 186 kg Oxytetracycline was used over 10 days the Oxytetracycline concentrations were determined under a single cage that received 8.65 kg Oxytetracycline during the treatment. Peak concentrations in the top 2 cm of the sediment were 9.9±2.9 μg·g −1 . This declined at an exponential rate ( r 2 =0.99) with a half-life of 16 days. At the second block the Oxytetracycline concentration was measured with a sampling programme designed to determine the horizontal and vertical distribution of Oxytetracycline under the whole cage block during and after a treatment where 175 kg of Oxytetracycline were used over 12 days. Peak concentrations, in the top 2 cm of the sediments under the cage block, were 10.9±6.5 μg·g −1 and this declined at an exponential rate ( r 2 =0.99) with a half-life of 13 days. Nineteen days after the end of the therapy Oxytetracycline was detected at depths of up to 8 cm in the sediment, but the concentration of the antibacterial agent had decreased at all levels in the sediment 14 days later. At the end of the treatment Oxytetracycline was detected in an area of the sediment less than twice the area of the cages themselves. Data on current flow and sedimentation rate were used to generate a predictive model of the area of sediment that would be subject to the deposition of both pelleted fish feed and fish faeces. Oxytetracycline was confined to the area of sediment predicted to be subject to feed deposition that was directly under and slightly to the west of the cage block. Oxytetracycline was not detected in the area predicted to be subject to faecal deposition only.

  • Frequency and distribution of resistance to Oxytetracycline in micro-organisms isolated from marine fish farm sediments following therapeutic use of Oxytetracycline
    Aquaculture, 1994
    Co-Authors: Joe Kerry, Rosie Coyne, Maura Hiney, Dave Cazabon, Saoirse Nicgabhainn, Pete Smith
    Abstract:

    Abstract the background level of resistance to Oxytetracycline in sediments free of anthrogogenic influences was determined on 2216 V agar with 25 μg·g −1 Oxytetracycline. The mean frequency of resistance in 153 samples taken in Galway Bay was 1.2 ±1.8%. The impact of Oxytetracycline therapy on the frequency of resistance in the sediments under a marine fish farm was investigated on two occasions. In the first investigation, Oxytetracycline was detected at a concentration of 9.9 ± 2.9 μg·g −1 in the sediments under a cage that received 865 g Oxytetracycline per day for 10 days, but no significant rise in resistance frequency was detected. In the second investigation, Oxytetracycline was detected at a concentration of 10.9 ± 6.5 μg·g −1 in the sediments under a cage block that received 175 kg Oxytetracycline over 12 days. The frequency of resistance reached 16.0 ± 8.9% after the treatment. The frequency declined at an exponential rate ( r 2 =0.89) with a half-life of 26 days. At 73 days after the end of therapy the frequency, in under-cage samples, was not significantly higher than the background level. At the end of the therapy elevated frequencies of resistance were detected up to 75 m from the edge of the cage block and in samples where the levels of Oxytetracycline were below the limit of detection (1.2 μg·g −1 ). Thirty-three days after the end of the therapy the frequency of resistance in all samples not directly under the cages was not significantly higher than in samples taken from sediments free of anthropogenic influence.

Joe Kerry - One of the best experts on this subject based on the ideXlab platform.

  • Concentration and persistence of Oxytetracycline in sediments under a marine salmon farm
    Aquaculture, 1994
    Co-Authors: Rosie Coyne, Maura Hiney, Brendan O'connor, Joe Kerry, Dave Cazabon, Pete Smith
    Abstract:

    Abstract The concentration of Oxytetracycline in the sediment under two adjacent cage blocks in a marine salmon farm was determined following the therapeutic use of the drug. The sediment cores were grey, indicating some build-up of organic material. Infaunal polychaetes were present as were mobile fauna including crabs, starfish and flat fish. There were no significant accumulations of undigested feed pellets under the cages. At one block where 186 kg Oxytetracycline was used over 10 days the Oxytetracycline concentrations were determined under a single cage that received 8.65 kg Oxytetracycline during the treatment. Peak concentrations in the top 2 cm of the sediment were 9.9±2.9 μg·g −1 . This declined at an exponential rate ( r 2 =0.99) with a half-life of 16 days. At the second block the Oxytetracycline concentration was measured with a sampling programme designed to determine the horizontal and vertical distribution of Oxytetracycline under the whole cage block during and after a treatment where 175 kg of Oxytetracycline were used over 12 days. Peak concentrations, in the top 2 cm of the sediments under the cage block, were 10.9±6.5 μg·g −1 and this declined at an exponential rate ( r 2 =0.99) with a half-life of 13 days. Nineteen days after the end of the therapy Oxytetracycline was detected at depths of up to 8 cm in the sediment, but the concentration of the antibacterial agent had decreased at all levels in the sediment 14 days later. At the end of the treatment Oxytetracycline was detected in an area of the sediment less than twice the area of the cages themselves. Data on current flow and sedimentation rate were used to generate a predictive model of the area of sediment that would be subject to the deposition of both pelleted fish feed and fish faeces. Oxytetracycline was confined to the area of sediment predicted to be subject to feed deposition that was directly under and slightly to the west of the cage block. Oxytetracycline was not detected in the area predicted to be subject to faecal deposition only.

  • Frequency and distribution of resistance to Oxytetracycline in micro-organisms isolated from marine fish farm sediments following therapeutic use of Oxytetracycline
    Aquaculture, 1994
    Co-Authors: Joe Kerry, Rosie Coyne, Maura Hiney, Dave Cazabon, Saoirse Nicgabhainn, Pete Smith
    Abstract:

    Abstract the background level of resistance to Oxytetracycline in sediments free of anthrogogenic influences was determined on 2216 V agar with 25 μg·g −1 Oxytetracycline. The mean frequency of resistance in 153 samples taken in Galway Bay was 1.2 ±1.8%. The impact of Oxytetracycline therapy on the frequency of resistance in the sediments under a marine fish farm was investigated on two occasions. In the first investigation, Oxytetracycline was detected at a concentration of 9.9 ± 2.9 μg·g −1 in the sediments under a cage that received 865 g Oxytetracycline per day for 10 days, but no significant rise in resistance frequency was detected. In the second investigation, Oxytetracycline was detected at a concentration of 10.9 ± 6.5 μg·g −1 in the sediments under a cage block that received 175 kg Oxytetracycline over 12 days. The frequency of resistance reached 16.0 ± 8.9% after the treatment. The frequency declined at an exponential rate ( r 2 =0.89) with a half-life of 26 days. At 73 days after the end of therapy the frequency, in under-cage samples, was not significantly higher than the background level. At the end of the therapy elevated frequencies of resistance were detected up to 75 m from the edge of the cage block and in samples where the levels of Oxytetracycline were below the limit of detection (1.2 μg·g −1 ). Thirty-three days after the end of the therapy the frequency of resistance in all samples not directly under the cages was not significantly higher than in samples taken from sediments free of anthropogenic influence.

Niels Henrik Spliid - One of the best experts on this subject based on the ideXlab platform.

  • sorption and mobility of metronidazole olaquindox Oxytetracycline and tylosin in soil
    Chemosphere, 2000
    Co-Authors: Mette Rabolle, Niels Henrik Spliid
    Abstract:

    Laboratory studies were conducted to characterise four different antibiotic compounds with regard to sorption and mobility in various soil types. Distribution coefficients (Kd values) determined by a batch equilibrium method varied between 0.5 and 0.7 for metronidazole, 0.7 and 1.7 for olaquindox and 8 and 128 for tylosin. Tylosin sorption seems to correlate positively with the soil clay content. No other significant interactions between soil characteristics and sorption were observed. Oxytetracycline was particularly strongly sorbed in all soils investigated, with Kd values between 417 in sand soil and 1026 in sandy loam, and no significant desorption was observed. Soil column leaching experiments indicated large differences in the mobility of the four antibiotic substances, corresponding to their respective sorption capabilities. For the weakly adsorbed substances metronidazole and olaquindox the total amounts added were recovered in the leachate of both sandy loam and sand soils. For the strongly adsorbed oxytetracyline and tylosin nothing was detected in the leachate of any of the soil types, indicating a much lower mobility. Results from defractionation and extraction of the columns (30 cm length) showed that 60-80% of the tylosin added had been leached to a depth of 5 cm in the sandy loam soil and 25 cm in the sand soil.