Simulating organic pollutant flows in urban stormwater: development and evaluation of a model for nonylphenols and phthalates.

Stormwater-quality models can be useful tools for predicting pollutant loads and identifying sources of contamination. Most models in current use handle pollutants such as metals, nutrients and suspended solids, whereas models including emerging organic contaminants are rare. This study aims at developing and evaluating a model for simulating stormwater flows of two groups of organic pollutants; nonylphenols and phthalates. Sources, emission patterns and environmental fate were examined to create a model framework for the organic contaminants. The model was calibrated using field data from three urban catchments. The results show that the simulated pollutant concentrations are overestimated compared to the measured concentrations, which are often close to or below the analytical detection limit. The high uncertainty and the low predictive power of the model may be explained by factors such as incorrect catchment data, lack of knowledge on buildup, washoff and other processes involved in substance fate, and an underreporting of pollutant concentrations in stormwater. More data on release patterns and sewer fate are needed to adequately simulate stormwater concentrations of nonylphenols and phthalates. A conventional substance flow analysis based on bookkeeping, evaluated in parallel to the computer model, has proven to be useful for calculating fluxes of nonylphenols and phthalates in urban catchments.

Leaching of organic contaminants from storage of reclaimed asphalt pavement.

Recycling of asphalt has been promoted by rapid increases in both the use and price of petroleum-based bitumen. Semi-volatile organic compounds in leachates from reclaimed asphalt pavement, measured in field samples and in laboratory column test, were analysed through a GC/MS screen-test methodology. Sixteen PAH (polyaromatic hydrocarbons) were also analysed in leachates from the column study. The highest concentrations of semi-volatile compounds, approximately 400 microg l(-1), were measured in field samples from the scarified stockpile. Naphthalene, butylated hydroxytoluene (BHT) and dibutyl phthalate (DBP) were the most dominant of the identified semi-volatiles. The occurrence of these compounds in urban groundwater, also indicate high emission rates and persistent structures of the compounds, making them potentially hazardous. Car exhausts, rubber tires and the asphalt material itself are all probable emission sources, determined from the organic contaminants released from the stockpiles. The major leaching mechanism indicated was dissolution of organic contaminants from the surface of the asphalt gravels. In the laboratory column test, the release of high-molecular weight and more toxic PAH was higher in the leachates after two years than at the commencement of storage. The concentrations of semi-volatiles in leachates, were also several times lower than those from the field stockpile. These results demonstrate the need to follow up laboratory column test with real field measurements.

Leaching of concrete admixtures containing thiocyanate and resin acids.

There is an increasing concern about the emission of pollutants during the construction and lifetime of buildings. The leaching of concrete admixtures containing thiocyanate and resin acids was studied using standard leaching tests and chemical analysis. Ecotoxicological risk was assessed for each admixture. Thiocyanate leaching from concrete, with a chlorine-free accelerating admixture, was determined by ion chromatography. Of the total amount of thiocyanate added, 6-8% was emitted within 30 d. The thiocyanate diffusion curve indicates a fast dissolution process from the surface layer, followed by a slower continuous diffusion process. Thiocyanate exhibits both acute and chronic toxicity, which makes it of immediate environmental concern. Resin acid leaching from concrete test specimens containing an admixture of air-entraining agents with tall oil was determined by solid-phase extraction, methylation, and GC/MS. Of added resin acids, 10% was emitted over 143 d. The leaching curves for the resin acids indicate a continuous diffusion that is proportional to the square root of time and follows Fick's first law of diffusion. The chemical composition of the resin acids in the leachate demonstrates degradation and rearrangement of the resin acids during diffusion. Resin acids emitted from concrete are of environmental concern because they are persistent and have the ability to bioaccumulate in aquatic organisms.

Monoterpenes emitted to air from industrial barking of Scandinavian conifers.

Monoterpenes released to air were determined during single-log barking of timber at a saw-mill and during tumble drum barking of pulpwood at a TMP mill. Characteristic proportions of fourteen compounds were assessed by adsorbent sampling and gas chromatography. For Scots pine (Pinus sylvestris), the bicylic monoterpenes alpha-pinene and 3-carene predominated. For Norway spruce (Picea abies), alpha-pinene followed by beta-pinene were the major components. The proportions of beta-phellandrene and myrcene from spruce were remarkably high from barking compared to wood processing. Environmental aspects on the emissions are discussed.

Photooxidant-forming monoterpenes in air plumes from kraft pulp industries.

Monoterpenes emitted to air from two Swedish kraft (sulphate) pulp-mills were determined by sampling on the Tenax adsorbent followed by laboratory analysis using thermal desorption combined with high-resolution gas chromatography. The composition of the terpenes was found to be similar in the emissions from various parts of the process as well as in the mill plume. The bicyclic terpenes alpha-pinene and 3-carene, originating principally from wood of Scots pine (Pinus sylvestris), predominated among the thirteen assessed hydrocarbon monoterpenes. Terpinolene was the most prominent among the particularly reactive terpenes with a lifetime in ozone-rich air of only a few minutes. The rapid formation of photooxidants by chemical reactions of the terpenes with other components of the mill plume is discussed. It is concluded that a variety of phytotoxic photooxidants are formed which may contribute significantly to forest decline within 50 km of mills located along coasts.

Exposure of commuters to volatile aromatic hydrocarbons from petrol exhaust.

Twenty-two volatile aromatic hydrocarbons were determined in the air of an automobile during commuting. Sampling was made on Tenax cartridges and laboratory determinations were carried out using thermal desorption combined with temperature-programmed capillary gas chromatography. Selected hydrocarbons representative of petrol exhaust were determined in the automobile and in an electric commuter train during eight parallel commuter trips. In the automobile, the concentrations of benzene were 35-70 micrograms/m3 and those of total aromatic hydrocarbons 200-400 micrograms/m3. The petrol exhaust levels were 5-10 times higher in the automobile than in the compartment of the commuter train.