A random selection of 186 water utilities was used for this study in which raw and finished water samples were collected from each facility five times throughout a year and analyzed for iron and aluminum by atomic absorption techniques. The water samples were categorized by the supply source (ground, surface, or a combination of both), the type of water (raw, finished, or untreated distribution samples), and the type of coagulation used in the treatment process (aluminum sulfate, ferric chloride, other coagulants such as cationic polymers, or no coagulant). The samples were also categorized according to the 10 US Environmental Protection Agency regions and 4 population categories. The results indicate that aluminum is more likely to exist in surface waters than in groundwaters and that there is a 40-50 percent chance that alum coagulation increases the aluminum concentration of finished water above its original concentration in the raw water.

The fate and transport of metallic pollutants through a watershed are related to the characteristics of undissolved solid particles to which they are bound. Removal of these particles and their associated pollutants via engineered structures such as settling ponds is one goal of stormwater management. Because the particles most often implicated in metal pollution have nominal diameters of <50 microm, Split-flow thin-cell (SPLITT) fractionation was investigated to study the metal loading as a function of particle settling rate. Several diverse particle samples--soil, urban dust, and parking deck sweepings--were fractionated using this technique, and the metal loadings were quantified with inductively coupled plasma-atomic emission spectrometry. Implications for stormwater management are discussed.

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The quality of potable water is such that the concentration of nutrients available for growth of microorganisms within distribution systems is limited. In such systems carbon is often the growth limiting nutrient. Research conducted in the Netherlands has indicated that low levels (<10 μg/L) of available organic carbon in water is sufficient to maintain an actively growing population of heterotrophic, or organic carbon utilizing, bacteria in aquatic systems. However, the ability of commercially available and cost effective technologies to achieve such low concentrations of assimilable organic carbon in full-scale water systems is doubtful. Reverse osmosis (RO) systems have been used for many years to effectively remove contaminants from source waters. We challenged a water distribution system simulator (DSS) with water from a municipal system and water that was treated using an RO system under two concentrations of residual free chlorine to evaluate the effect of this disinfectant on biofilms in contact with low nutrient water. Our results showed that biofilm densities in the DSS carrying low nutrient RO treated water were lower than biofilm densities taken from the DSS when it carried water directly obtained from a municipal system.Key words: water distribution systems, reverse osmosis, biofilms, heterotrophic plate count, HPC, chlorine, assimilable organic carbon.

Analytical chemistry is an important tier of environmental protection and has been traditionally linked to compliance and/or exposure monitoring activities for environmental contaminants. The adoption of the risk management paradigm has led to special challenges for analytical chemistry applied to environmental risk analysis. Namely, methods developed for regulated contaminants may not be appropriate and/or applicable to risk management scenarios. This paper contains examples of analytical chemistry applied to risk management challenges broken down by the analytical approach and analyte for some selected work in our laboratory. Specific techniques discussed include stable association complex electrospray mass spectrometry (cESI-MS), gas chromatography-mass spectrometry (GC-MS), split-flow thin cell (SPLITT) fractionation and matrix-assisted laser desorption time of flight mass spectrometry (MALDI-ToF-MS). Specific analytes include haloacetic acids (HAA9), perchlorate, bromate, triazine degradation products, metal-contaminated colloids and Cryptosporidium parvum oocysts.