The lack of an adequate method for calibration of time domain reflectometry (TDR) measurement on bulk soil electrical conductivity is a limiting factor, especially for field‐scale solute transport study. This study investigated an appropriate calibration method that can be applied to horizontally positioned TDR probes in situ. A nonlinear model (RM) has been proposed assuming a two‐pathway conductance. Using the quadratic form, the RM equated electrical conductivity in the immobile phase of soil solution (ECws) in a series‐coupled pathway with electrical conductivity in the mobile phase of soil solution (ECwc) in a continuous pathway. We related bulk soil electrical conductivity (ECa) to electrical conductivity of soil water (ECw), assuming constant ECws during breakthrough. This resulted in a linear relationship between ECa and ECw. The linear relation, termed here simple linear model (SLM), was tested using experimental data obtained from soil columns. Laboratory breakthrough experiments were performed on short and large columns by applying a pulse input of solute. At the end of breakthrough, separate calibration experiments were performed using a step input of solute. Both RM and SLM were compared with the step input calibration method (SIM) as a reference method. Results show that the SLM is better than RM in terms of mass recovery. In addition, parameters of the solute transport model were not affected within 20% of uncertainty in the slope coefficient of the SLM when compared with the reference method. Advantages of the SLM are that it has an identical equation form to the SIM but less effort is required, especially for soil columns showing preferential flow, and it can be readily applied to field conditions.

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Pseudomonas putida is well known as a toluenedegrading bacterium. Because methyl tert-butyl ether (MTBE) often coexists with toluene in subsurface environment, in this study we investigated substrate interactions between toluene and MTBE, and their degradation potential in mixtures by Pseudomonas putida. Batch microcosm studies were conducted for a wide concentration range (25-200 mg L 21 ) to monitor bacterial growth associated with toluene and/or MTBE degradation using Pseudomonas putida previously adapted to toluene. We found that the effect of MTBE on toluene degradation was strongly concentration-dependent, and that concentrations of either toluene or MTBE as low as 25 mg L 21 can enhance degradation of other compound, but those concentrations higher than 25 mg L 21 tend to result in negative or no effect. The negative effect was more pronounced for toluene since MTBE degradation was inhibited at a concentration of 50 mg L 21 or higher toluene. This indicates that concentrations of cocontaminants become a limiting factor for bioremediation of groundwater. Therefore, for higher degradation efficiency, care should be taken in the selection of concentration ranges of toluene and MTBE.

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S388Poster presentations year with a median stay of 10 days . The reasons for hospitalisation were: 36 (45%) for CD recurrence or active disease and 35 (44%) from surgical-related complications, 1 (1%) for infection and 7 (9%) for other reasons. At 5 years, 94 (30%) patients had required hospitalisation, mostly for recurrent active disease. 45 (14%) patients required reoperation within 5 years, with 23/45 (51%) during the first year, and the most common reason was surgical complications. (18/45, 40%). The median time to first reoperation was 228 days . At year 5, 22 patients needed reoperation due to CD activity, the most common reason was fistulae (11/22, 50%). No differences in the 5-year surgical recurrence were found in those with or without prophylaxis (Table 1). Conclusions: During the CD related post-surgery evolution, around 20% of the patients will require hospitalisation for postoperative complications during the first year and 30% will require hospitalisation at 5 years follow-up due to disease recurrence. 14% will require a new reintervention after 5 years. Background: Ulcerative colitis (UC) is a major type of IBD with periods of waxing and waning. Intestinal blood loss is an major symptom in UC and stool Hb level correlated well with the endoscopic disease activity of UC patients. Fecal calprotectin (FC) level increases at gut inflammation and correlate well with endoscopic disease activity in UC. We evaluated the usefulness of FC, quantitative stool Hb (SHb), and CRP as a marker for reflecting UC disease activity Methods: A total 106 UC patients who performed FC, SHb, CRP, and endoscopy at Korea University Hospital through March 2015 to August 2016 were retrospectively reviewed. UC disease severity was assessed using partial Mayo score (remission=0-1, mild=2-4, moderate=5-6, severe=7-9) and Mayo endoscopic score (remission=0, mild=1, moderate=2, severe=3). The ability of tests for reflecting disease severity was compared using Receiver Operator Characteristic-Area under the Curve (ROC-AUC) statistic. Results: Among 106 patients, 26 patients have moderate to severe activity based on partial Mayo score. The area under the curve (AUC) in ROC analysis of SHb and FC to predict partial Mayo score more than 1 were 0.717 and 0.727 (AUC of CRP, 0.549). There was no significant difference between SHb and FC (PSHb vs CRP: 0.007, PFC vs CRP: 0.006, PSHb vs FC: 0.864). For detecting Mayo endoscopic score 1 or more, the AUC of SHb and FC were 0.956, 0.942 (AUC of CRP, 0.756, p<0.05). Conclusions: SHb and FC can effectively and noninvasively detect mild to moderate UC. Considering that SHb and FC reflects the status of mucosal inflammation and disease activity well, they might reduce the requirement for invasive endoscopic examinations. P604