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Wood chips were evaluated for their ability to attenuate heavy metals in roadway runoff. Column experiments with controlled synthetic runoff composition and flow rate were used to assess effects of flow rate (intercepted sheetflow from a 3-m wide roadway section), runoff salt concentration, wood exposure to alternating wetting and drying cycles, wood aging, competition among dissolved heavy metals, and removal of particle-associated heavy metals. Overall, wood chips damped the 'pulse' of copper in the synthetic runoff such that the effluent was characterized by lower concentrations (3-25% of input) over longer periods of time, but with little retention of the total copper mass. The most effective treatment was wood chips aged up to 9 months. Increased aging and chip water content reduced effluent concentrations, relative to no treatment. Flow rate had no effect on effluent concentrations. The presence of salt (>2 mS/cm) or dissolved lead (500 [micro]g/L) in the runoff caused greater copper effluent concentrations than the no treatment case. Removal of suspended particles (and associated contaminants) was greater than 85% with an estimated capacity of 0.16 g/[g.sub.wood]. Field evaluation with concentrated flow to a gutter containing a wood chip treatment showed little effect on total or dissolved copper and zinc runoff concentrations and indicated that wood chips may be a source of contaminants in subsequent storm events. Applications of wood chips to treat roadway runoff would not provide a significant decrease in total maximum daily load contributions (e.g., kg/d); however, there may be some scenarios for which wood chip treatments to decrease peak storm water concentrations of dissolved heavy metals in sheetflow runoff is desirable. DOI: 10.1061/(ASCE)EE.1943-7870.0000034 CE Database subject headings: Runoff; Highways and roads; Urban areas; Stormwater management; Water quality; Copper; Metals; Wood; Sorption; Attenuation.

A mathematical model was developed to estimate the efficacy of coagulation-flocculation treatment for removing neutral hydrophobic organic chemicals from raw drinking water. The model assumed that the only significant removal mechanism was the destabilization and settling of organic matter containing sorbed anthropogenic organic compounds. The model was validated with standard jar tests using compounds with a range of hydrophobicities (log [K.sub.ow] = 1.89 to 5.48), including contaminant candidate list chemicals, pesticides, pharmaceuticals, and endocrine disrupting chemicals. Final concentrations of test compounds after coagulation and flocculation were in good agreement with model estimations for synthetic waters composed of Aldrich (Milwaukee, WI) humic acid solutions. The final compound concentrations in coagulated natural waters from two drinking water reservoirs were about 80% lower than those estimated with the model. Overestimations of treated water concentrations by the model were attributed to an increase in sorption by natural organic matter when coiled in aluminum hydroxide flocs, compared to sorption to dispersed natural organic matter in untreated water. DOI: 10.1061/(ASCE)0733-9372(2005)131:1(108) CE Database subject headings: Organic chemicals; Potable water; Coagulation; Flocculation; Water treatment; Abatement and removal; Mathematical models.

The concentrations of groundwater polycyclic aromatic hydrocarbons at a coal tar site were round to be elevated by factores of 3 to 50 over purely dissolved concentrations by association with humic acid-like colloids.

Experiments on the absorption of toluene, 0-xylene and benzene to wood are described. The results could be used to help predict organic contaminant transport at landfills, which often contain up to 25% wood waste by weight.

A Midwestern waste site contaminated with benzene, toluene, ethylbenzene and xylenes (BTEX) exhibits kinetically limited desorption and non-aqueous phase liquid dissolution. BTEX soil flushing was used to assess which mechanisms inhibit flushing as a remediation approach at a particular field site for an evaluation of the efficiency of different cleanup methods. The method involves applying water at the surface of the soil and flushing vertically by gravity infiltration. Water would then be recovered using pumping wells and treated at the land surface.

Ultrahigh resolution mass spectrometry (UHR-MS) is commonly used to characterize natural organic matter (NOM). The complexity of both NOM and the data set produced make data visualization challenging. Van Krevelen diagrams─plots of component hydrogen/carbon (H/C) against oxygen/carbon (O/C) elemental ratios─have become a popular way to visualize the chemical formulas identified by UHR-MS. Different regions on the van Krevelen diagram have been attributed to different chemical classes; however, the classifications vary between studies and the regions lack standard definitions. Here, chemical formulas were obtained from public databases to create H/C and O/C ranges for amino sugar, carbohydrate, lignin, lipid, peptide, and tannin chemical classes on van Krevelen diagrams. The recommended H/C and O/C ranges are presented in a table and can be adapted to any data analysis software programs. The regions recommended here agreed reasonably well with previous literature for amino sugar, carbohydrate, lignin, lipid, and peptide regions. However, the recommended tannin region appears at lower H/C ratio values and with a wider range of O/C ratio values compared to previous studies. The regions presented herein are strongly recommended for use as consistent reference points in future NOM characterization studies to aid in the discussion of data and to readily compare studies. [ABSTRACT FROM AUTHOR]