The influence of untreated wastewater to aquatic communities in the Balatuin River,The Philippines

A risk assessment of chemical constituents in rivers that receive untreated wastewater should take into account the adverse effects of increased biological oxygen demand (BOD), ammonia and reduced dissolved oxygen (DO). This concept was tested via a field study in the Balatuin River, The Philippines, where the influence of physical and chemical factors, including the consumer product chemical linear alkylbenezene sulfonate (LAS), to aquatic communities (algae, invertebrates, fish) was determined. Periphytic algae were found to be insensitive to high BOD (>10 mg/l) and ammonia (>0.01 mg unionized NH(3)/l), concentrations from organically enriched untreated wastewater discharges. However, taxa richness and abundance of macroinvertebrates were influenced greatly by the discharges. Where BOD and ammonia concentrations were elevated, the dominant taxa were oligochaete worms and chironominds. Fish and crustaceans (freshwater crabs and prawns) were found only in sites with the least BOD concentrations (furthest upstream and downstream). The maximum concentration of LAS (0.122 mg/l) was less than that expected to affect 5% of taxa (0.245 mg/l), whereas exceedences of DO and ammonia criteria were observed in several sites. The lack of recovery observed was attributed to influences of low DO, high ammonia and poor colonization from upstream and downstream reaches due to organically-enriched discharges     

Microbial source tracking of Escherichia coli in a constructed wetland.

Little information has been gathered on the effect of avian species on the microbial water quality in constructed wetlands. To address this concern, fecal pollution from nonpoint and point sources was evaluated in a constructed wetland in Tolleson, Arizona. Antibiotic resistance profiling and biochemical fingerprinting were performed on 325 Escherichia coli isolates, collected from key points in the wetlands. Multivariate statistical analysis was used to interpret the data for samples collected on October 3 and December 12, 2000, and January 16, 2001. It was found that the passerine population was the major source of the Escherichia coli in the water samples collected in the wetlands on October 3 and December 12, 2000, whereas the regrowth in the treated municipal wastewater was the main source on January 16, 2001. This information is useful in providing data for operators in the monitoring of wetlands created for wastewater treatment and wildlife habitat.     

Toxicity of chemical components of fine particles inhaled by aged rats: effects of concentration

This study tested the hypothesis that exposure to mixtures containing fine particles and ozone (O3) would cause pulmonary injury and decrements in functions of immunological cells in exposed rats (22-24 months old) in a dose-dependent manner. Rats were exposed to high and low concentrations of ammonium bisulfate and elemental carbon and to 0.2 ppm O3. Control groups were exposed to purified air or O3 alone. The biological end points measured included histopathological markers of lung injury, bronchoalveolar lung fluid proteins, and measures of the function of the lung's innate immunological defenses (macrophage antigen-directed phagocytosis and respiratory burst activity). Exposure to O3 alone at 0.2 ppm did not result in significant changes in any of the measured end points. Exposures to the particle mixtures plus O3 produced statistically significant changes consistent with adverse effects. The low-concentration mixture produced effects that were statistically significant compared to purified air but, with the exception of macrophage Fc receptor binding, exposure to the high-concentration mixture did not. The effects of the low- and high-concentration mixtures were not significantly different. The study supports previous work that indicated that particle + O3 mixtures were more toxic than O3 alone.     

Sequential anaerobic-aerobic treatment of an aquifer contaminated by halogenated organics: field results

In situ, sequential, anaerobic to aerobic treatment of groundwater removed perchloroethene (PCE, 1.1 microM) and benzene (0.8 microM) from a contaminated aquifer. Neither aerobic nor anaerobic treatment alone successfully degraded both the chlorinated and non-chlorinated organic contaminants in the aquifer. After the sequential treatment, PCE, trichloroethene (TCE), vinyl chloride (VC), chloroethane (CA), and benzene were not detectable in groundwater. Desorption of residual aquifer contaminants was tested by halting the groundwater recirculation and analyzing the groundwater after 3 and 7 weeks. No desorption of the chlorinated contaminants or daughter products was observed in the treated portion of the aquifer. Sequential anaerobic to aerobic treatment was successful in remediating the groundwater at this test site and may have broad applications at other contaminated sites. Over the 4-year course of the project, the predominant microbial environment of the test site varied from aerobic to sulfate-reducing, to methanogenic, and back to aerobic conditions. Metabolically active microbial populations developed under all conditions, demonstrating the diversity and robustness of natural microbial flora in the aquifer.     

The effect of particle size reduction by grinding on subsampling variance for explosives residues in soil

Efforts to characterize the surface soil contamination on military training ranges have been compromised by the inability to obtain representative subsamples of soils submitted to analytical laboratories for determination of explosives residues. Two factors affecting subsampling error for explosives residues were examined using soils collected from hand grenade and anti-tank ranges. These factors were increased subsample size and particle size reduction prior to subsampling of soils. Increasing the subsample size from 2 to 50 g did not reduce the soil subsampling error because of the extreme heterogeneous distribution of the solid contaminants. Alternatively, particle size reduction by machine grinding on a ring mill reduced subsampling error to less than 10% relative standard deviation for replicate analyses using 10-g subsamples.     

The effect of cadmium ion on the growth,photosynthesis, and nitrogenase activity of Anabaenainaequalis

The growth of $\text{Anabaena}$$\text{inaequalis}$ was significantly inhibited by Cd²⁺ concentrations greater than 0.02 ppm (μg/ml) and completely inhibited at 0.06 ppm (Day 12). Cadmium had no significant effect upon the lag phase of growth or the culture doubling time, but caused the retardation phase to arrive sooner. One ppm Cd²⁺ significantly inhibited the rates of both photosynthesis and acetylene reduction, by $\text{A}$. $\text{inaequalis}$, with complete inhibition at 4 and 20 ppm respectively. Cell sensitivity increased directly with exposure time. Cadmium caused some cell lysis of $\text{A}$. $\text{inaequalis}$ and induced an increase in filament length, heterocyst frequency, and a loss of cellular contents from filament apical cells. The cellular abnormalities observed and the fact that toxicity increased with longer exposure times, suggested that metal toxicity resulted from effects of Cd²⁺ taken up by cells rather than Cd²⁺ at the cell surface.     

Understanding the effectiveness of precursor reductions in lowering 8-hr ozone concentrations

Analyses of ambient measured ozone data were used in conjunction with the application of photochemical modeling to determine the technical feasibility of attaining the federal 8-hr ozone standard in central California. Various combinations of volatile organic compound (VOC) and oxides of nitrogen (NOx) emission reductions were effective in lowering modeled peak 1-hr ozone concentrations. However, VOC emissions reductions were found to have only a modest impact on modeled peak 8-hr ozone concentrations. NOx emission reductions generally lowered 8-hr ozone concentrations, but their effectiveness was partially or, in some cases, wholly offset by the increase in the number of NO cycles and, hence, in the ozone produced per NO. As a result, substantial NOx emission reductions--70 to 90%--were required to reduce peak 8-hr ozone concentrations to the level of the standard throughout the modeling domain. These modeling results provide a possible physical explanation for recent analyses that have reported more prominent trends in peak 1-hr ozone levels than in peak 8-hr ozone concentrations or in occurrences of mid-level (60-90 parts per billion by volume) ozone concentrations. The findings also have serious implications for the feasibility of attaining the 8-hr ozone standard in central California. Further efforts are needed to clarify the applicability of the modeling results to the full set of days with ozone levels exceeding the 8-hr ozone standard, as well as their applicability to other geographical areas.     

Effect of a base-catalyzed dechlorination process on the genotoxicity of PCB-contaminated soil

We evaluated the genotoxicity of dichloromethane (DCM) extracts of PCB-contaminated soil before and after the soil had been treated by a base-catalyzed dechlorination process. The treatment process involves heating a mixture of the soil, polyethylene glycol (or hydrocarbons with boiling points of 310–387°C), and sodium hydroxide to 250–350°C. Dechlorination reduced by >99% the PCB concentration of the soil, which was initially 2,200 ppm. The DCM extracts of both control and treated soils were not mutagenic in strain TA100 of Salmonella, but they were mutagenic in strain TA98. Based on results in strain TA98, the base-catalyzed dechlorination process reduced the mutagenic potency of the soil by approximately one-half. The DCM extracts of the soils before and after treatment were equally genotoxic in a prophage-induction assay in . , which detects some chlorinated organic carcinogens that are not detected by the Salmonella mutagenicity assay. These results suggest that treatment of PCB-contaminated soil by base-catalyzed dechlorination reduced the mutagenicity of the soil slightly.     

Operational dumping and the pollution of the sea by oil: An evaluation of preventive measures

The recent dispute over the impact of economic growth on the environment relative to the (predicted) physical limits imposed by the ecological system hinges on the role of pollution-preventive technology. This paper attempts a cost-effectiveness evaluation of alternative methods of preventing the largest source of marine oil pollution. The first major result of the analysis is that the technology which minimizes internal costs (and is favored by the oil companies) does not minimize the social costs of pollution prevention. The second is that relative to the price of oil the cost of pollution-prevention processes is very small indeed.     

Perceived enjoyment,concentration, intention,and speed violation behavior: Using flow theory and theory of planned behavior

Objective: Road accidents are an important public health concern, and speeding is a major contributor. Although flow theory (FLT) is a valid model for understanding behavior, currently the nature of the roles and interplay of FLT constructs within the theory of planned behavior (TPB) framework when attempting to explain the determinants of motivations for intention to speed and speeding behavior of car drivers is not yet known. The study aims to synthesize TPB and FLT in explaining drivers of advanced vehicles intentions to speed and speed violation behaviors and evaluate factors that are critical for explaining intention and behavior.

Method: The hypothesized model was validated using a sample collected from 354 fully licensed drivers of advanced vehicles, involving 278 males and 76 females on 2 occasions separated by a 3-month interval. During the first of the 2 occasions, participants completed questionnaire measures of TPB and FLT variables. Three months later, participants' speed violation behaviors were assessed.

Results: The study observed a significant positive relationship between the constructs. The proposed model accounted for 51 and 45% of the variance in intention to speed and speed violation behavior, respectively. The independent predictors of intention were enjoyment, attitude, and subjective norm. The independent predictors of speed violation behavior were enjoyment, concentration, intention, and perceived behavioral control.

Conclusions: The findings suggest that safety interventions for preventing speed violation behaviors should be aimed at underlying beliefs influencing the speeding behaviors of drivers of advanced vehicles. Furthermore, perceived enjoyment is of equal importance to driver's intention, influencing speed violation behavior.