Dissolved component recovery following resin exchange based DOM fractionation

Organic and inorganic components in natural waters are intimately interrela ted and constitute a dissolved material matrix (DMM). The objective of this study was to systematically investigate the distribution and recovery of b oth organic and inorganic components in chemically fractionated natural wat ers. Untreated and previously coagulated natural waters were fractionated i nto hydrophobic and hydrophilic acid, base, and neutral DMM fractions using a resin exchange based protocol. Mass balances on nonpurgable dissolved or ganic carbon, aluminum, iron, and manganese were used to evaluate DMM compo nent recovery. Quantitative recovery of dissolved organic matter was achiev ed, whereas, aluminum, iron, and manganese recoveries were largely incomple te (30-92%). Coagulation increased the recovery of all metals examined. Inc omplete metals recovery was attributed to imperfect elution from MSC-1 cati on exchange resin and appeared related to the distribution coefficient K-d of each metal with this resin. DMM component distribution among chemical fr actions was altered by coagulation, with dissolved organic matter preferent ially removed in the hydrophobic acid fraction. Unrecovered metals appeared to consist primarily of colloidal mineral (hydr)oxides solubilized by acid ic pH conditions imposed during fractionation.