Heavy metal toxicity in water varies greatly as environmental factors including pH, cations and dissolved organic carbon (DOC) change, which means its toxicity would be different to different organisms according to the surrounding conditions even though the total concentration of the heavy metal remains the same. To consider those factors, the new model called biotic ligand model (BLM) was developed in 2001 predicting heavy metal concentration in water system using fish gill as a ligand where the metal binds to. The BLM has been used widely but its limitation is that it does not reflect the temporal variation of those environmental factors. The seasonal variations of the pH, DOC or ion concentrations are not taken into account when evaluating the heavy metal toxicity and to deal with this problem, fixed monitoring benchmarks (FMB) method was introduced by HydroQual in 2008. FMB determines site-specific permissible concentration using a distribution of toxic unit (TU) dividing BLM-predicted safe concentrations by the dissolved heavy metal concentrations in site water.<br/>In this study, the FMB was applied to local river system in Han River, Seoul, S.Korea to determine acceptable concentrations of heavy metal among varying instantaneous water quality criteria (IWQC) which is calculated through the BLM with Daphnia Magna. With the temporal variation of the BLM-predicted safe concentrations over 30months of sampling period, the FMB method yields a single number that could be a site-specific standard to the local water system. Five heavy metals including Cu, Zn, Pb, Cd and Ni in Han River were evaluated.<br/>With successful application of FMB to the river system, the idea of FMB could be expanded to determine the heavy metal acceptable concentration in soil using soil pore-water. The environmental factors in the pore-water also vary as time goes so such change influences the determination of site-specific heavy metal concentration and its acceptable concentration. To determine the IWQC values using the BLM, barley was chosen as it’s a sensitive species to toxicity and changing environment. <br/>By considering the changing environmental factors over time, the fixed-site criterion for targeted heavy metal could be developed in local river system in Seoul, South Korea and the concept of FMB was also applied to soil pore-water to develop the acceptable heavy metal concentrations.<br/>

Determination of heavy metal acceptable concentration using fixed monitoring benchmarks in river system and soil pore-water in S.Korea

254th National Meeting (2017)

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