THE EFFECT OF SALT ON SMALL,ARTIFICIAL LAKES1

ABSTRACT: Northridge Lakes, in Milwaukee, Wisconsin, receive runoff from a 3.8 square kilometer drainage area. Almost 30% of the watershed is covered by shopping centers, apartment buildings, and roadways. Deicing agents used on the paved areas, primarily NaCl with some CaCl₂, dissolved in surface runoff and entered the lakes during the winter season. This highly saline inflow was denser than the receiving lake water and formed a saline-water stratum at the lakes' bottom. The salinity stratification remained stable until the spring thaw when a rapid decay began. After the stratification had disappeared, the lakes continued to act as a storage site for dissolved salts. Chloride concentrations in the lakes remained well above the levels found in natural lakes until the advent of the next salting season. Furthermore, outflow from the lakes also showed abnormally high salt concentrations year-round.     

Real-world vehicle emissions: A summary of the 15th coordinating research council on-road vehicle emissions workshop

The Coordinating Research Council held its 15th workshop in April 2005, with nearly 90 presentations describing the most recent mobile source-related emissions research. In this paper, the authors summarize the presentations from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles (with an emphasis in this workshop on particle emissions), effects of fuels on emissions, evaluation of in-use emissions control programs, and efforts to improve our capabilities in performing on-board emissions measurements, as well as topics for future research.     

Free Trade Is Green, Protectionism Is Not

Many writers argue that free trade will lead to environmental degradation. Most environmentally pernicious public policies, however, such as subsidies of timber extraction and ranching, are also trade protectionist policies. To the extent that free trade treaties, such as the General Agreement on Tariffs and Trade, do away with such trade protectionism, free trade instead could be viewed as a major pathway to environmental reform. Furthermore, trade liberalization is associated with urbanization and industrialization, both of which reduce population growth rates and the pressures of colonization. I suggest that we, as environmentalists, can ally ourselves with free traders.     

Localized defecation by pike: a response to labelling by cyprinid alarm pheromone?

Fathead minnows (Pimephales promelas) that have never encountered a predatory pike (Esox lucius), are able to detect conspecific alarm pheromone in a pike's diet if the pike has recently consumed minnows. It remains unclear how this minnow alarm pheromone is secreted by pike and if a pike is able to avoid being labelled as a potential predator by localizing these cues away from its foraging range. The first experiment determined that minnow alarm pheromone is present in pike feces when pike are fed minnows. Individual fathead minnows exhibited a fright response to a stimulus of pike feces if the pike had been fed minnows, but not if the pike had been fed swordtails, which lack alarm pheromone. Individual minnows also exhibited a fright reaction to alarm pheromone in the water (which contained no feces) housing pike which had been fed minnows, suggesting that alarm pheromone is also released in urine, mucous secretions and/or via respiration. The second experiment determined that test pike spent a significantly greater proportion of time in the home area of the test tanks (i.e. where they were fed) but the majority of feces were deposited in the opposite end of the test tank. By localizing their defecation away from the home or foraging area, pike may be able to counter the effects of being labelled as a predator by the alarm pheromone of the prey species.     

A screening study of the treatability of dioxins and furans in bleach plant filtrates and mill wastewaters

Findings are presented of a study to provide the pulp and paper industry with basic data regarding the feasibility for treatment of bleach plant filtrates or combined treated mill effluents for 2,3,7,8-TCDD and 2,3,7,8-TCDF reduction.     

The effects of atmospheric nitrogen deposition in the Rocky Mountains of Colorado and southern Wyoming, USA-a critical review

The Rocky Mountains of Colorado and southern Wyoming receive atmospheric nitrogen (N) deposition that ranges from 2 to 7 kg ha(-1) yr(-1), and some previous research indicates pronounced ecosystem effects at the highest rates of deposition. This paper provides a critical review of previously published studies on the effects of atmospheric N deposition in the region. Plant community changes have been demonstrated through N fertilization studies, however, N limitation is still widely reported in alpine tundra and subalpine forests of the Front Range, and sensitivity to changes in snow cover alone indicate the importance of climate sensitivity in these ecosystems. Retention of N in atmospheric wet deposition is <50% in some watersheds east of the Continental Divide, which reflects low biomass and a short growing season relative to the timing and N load in deposition. Regional upward temporal trends in surface water NO(3)(-) concentrations have not been demonstrated, and future trend analyses must consider the role of climate as well as N deposition. Relatively high rates of atmospheric N deposition east of the Divide may have altered nutrient limitation of phytoplankton, species composition of diatoms, and amphibian populations, but most of these effects have been inconclusive to date, and additional studies are needed to confirm hypothesized cause and effect relations. Projected future population growth and energy use in Colorado and the west increase the likelihood that the subtle effects of atmospheric N deposition now evident in the Front Range will become more pronounced and widespread in the future.     

Bioavailability of 2,3,7,8-tetrachlorodibenzo-p-dioxin from municipal incinerator fly ash to freshwater fish

The bioavailability of 2,3,7,8-TCDD from municipal incinerator fly ash to freshwater fish was determined. It was observed that carp exposed to fly ash containing all 22 TCDD isomers, or the solvent extract of the fly ash, retain only 2,3,7,8-TCDD. Exposures with fly ash appears to follow a dose response relationship for bioconcentration, however, the bioavailability of 2,3,7,8-TCDD was not directly related to the level of 2,3,7,8-TCDD in fly ash for two fly ash samples studied.     

PCBs and DDT in Saginaw Bay white suckers

Fillets from 25 white suckers ( ) obtained from the Saginaw Bay, Lake Huron commercial fishery were analyzed for PCBs and ∑DDT (DDE-DDD-DDT). PCB levels ranged from 0.01 – 0.18 ppm while ∑DDT levels ranged from < 0.001 – 0.044 ppm. These results, combined with previous survey data, indicate steady declines in the levels of these contaminants in Saginaw Bay suckers.     

Evaluation of reverse phase liquid chromatography/mass spectrometry for estimation of n-octanol/water partition coefficients for organic chemicals

A reverse-phase high pressure liquid chromatography/mass spectrometry (HPLC/MS method was developed for estimating n-octanol/water partition coefficients (K_ow) of anthropogenic molecules in complex chemical mixtures (e.g., complex effluents and solid waste leachates). The average error for an estimated log K_ow was ca. 0.5 and this error was similar for both aliphatic and aromatic compounds. The minimum level of detection using the total ion current profile generally decreased with increasing molecular weight between 100 and 600 daltons. Results obtained demonstrate that the HPLC/MS method is a viable technique for estimating log K_ow's of anthropogenic chemicals in complex environmental samples.