Ways of improving the management of environmental risks

From the public's discovery of environmental quality in the late 1960s to the present, there has been increasing recognition that a more systematic approach is required to manage risks and to achieve the gains at low cost. Such a systematic approach must begin with risk identification, then go on to risk assessment, consideration of management options, a decision analysis of the options, and an examination of strategies for reducing loss. One of the most difficult aspects of environmental risk management is setting goals. There is a tendency to engage in rhetoric about zero risks and a pristine environment. However, moving toward more realistic goals requires consideration of what is an acceptable risk level. This level cannot be defined without knowing the benefits that come with the risk and the costs of reducing the risk. More generally, the criteria for selecting a risk management strategy include the residual level of risk, efficiency in reducing risk, equity, administrative simplicity, and public acceptability. A number of frameworks are currently used by U.S. regulatory agencies to manage risk: no-risk, risk-risk, technology-based standards, risk-benefit, cost-effectiveness, regulatory budget, and benefit-cost analysis. In specifying that an agency must use one of these frameworks, the U.S. Congress is implicitly specifying the goals for risk reduction. It appears to be easier for the U.S. Congress to specify a framework than a goal. Some of the nonregulatory means of managing risk include the market, and legal mechanisms. These risk management institutions have been effective and are a necessary part of any risk management program.     

The partitioning of alkylphenolic surfactants and polybrominated diphenyl ether flame retardants in activated sludge batch tests

Polybrominated diphenyl ethers and nonylphenol polyethoxylates have been reported to be estrogenic and may enter the aquatic environment through the discharge of treated sewage effluent. Therefore, their fate during wastewater treatment processes is an important factor in determining their environmental impact. Batch tests with activated sludge from a Husmann apparatus were used to determine the effects of physico-chemical properties and sludge characteristics on the partitioning of polybrominated diphenyl ether flame retardants and nonylphenol polyethoxylate surfactants during biological wastewater treatment. Hydrophobic compounds, those with high logK(ow) values, were sorbed more rapidly and to a greater extent to the solid phase than more soluble compounds. For these hydrophobic compounds sorption may become an increasingly important removal mechanism as sludge age and therefore solids content increase. The initial rate of partitioning was greatest for the most hydrophobic compounds but all rates diminished with time as a result of progressive saturation of sorbent binding sites, a reduction of sorbate availability and as a consequence of the system reaching equilibrium. The sorption of polybrominated diphenyl ethers fit Freundlich adsorption isotherms demonstrating generally increasing adsorption capacity and efficiency with increasing hydrophobic nature. A correlation between increasing logK(ow) and increasing organic matter content was also observed for both polybrominated diphenyl ethers and nonylphenol polyethoxylates indicating the organic content of mixed liquor will also be influential in removing compounds during wastewater treatment.     

A sensitive and robust method for the determination of alkylphenol polyethoxylates and their carboxylic acids and their transformation in a trickling filter wastewater treatment plant

This paper presents a method for the determination of alkylphenols, alkylphenol polyethoxylates (APEO) and alkylphenol ethoxycarboxylates (APEC) in the aqueous and particulate phase of wastewater samples. Quantification was achieved by liquid chromatography-tandem mass spectrometry. The sensitivity of the method is demonstrated by low detection limits, in the dissolved phase 1.2-9.6ngl(-1) for alkylphenol, AP(1-3)EO and APEC and 0.1-4.1ngl(-1) for longer chain alkylphenol polyethoxylates. The method detection limit for particulate phase samples ranged from 6 to 60ngg(-1) for AP, AP(1-3)EO and APEC; with the longer chain APEO being from 0.5 to 20ngg(-1). Matrix effects were noted in complex matrix rich samples. There was a distinct change in the distribution of alkylphenol ethoxylates during biological treatment of the wastewater, with the major biotransformation products observed being carboxylated derivatives at concentrations of up to 1768ngl(-1). Shorter chain APEO were present in higher proportions in the suspended solids, due to their higher affinity to particulate matter compared to the long-chain oligomers.     

Assessing the potential of using phytoremediation for pyrene‐contaminated soils

Forage crop species representing two biologically distinct families (legumes and grasses) were evaluated on soil spiked with 100 mg/kg of pyrene to determine the potential effectiveness of the rhizospheres of these plants for phytoremediation. In this experiment, pyrene dissipation could not be attributed to the presence of plants. Pyrene dissipation was also not related to rhizosphere biological activity, such as microbial counts and enzyme activity. Planting with reed canarygrass and switchgrass significantly increased the microbial counts in soil; however, the differences in the microbial counts were not correlated to the levels of pyrene dissipation. Reed canarygrass rhizosphere had significantly higher dehydrogenase activity compared to the switchgrass rhizosphere, but this difference in soil dehydrogenase activity was not related to pyrene dissipation. In general, the use of plants was not effective in causing pyrene transformation; however, the presence of vegetation on polycyclic aromatic hydrocarbon–contaminated soils could play a significant role in limiting the spread of contaminants (erosion, leaching) and enhancing ecosystem restoration. © 2004 Wiley Periodicals, Inc.     

Book reviews

ANALYTICAL PLANNING: THE ORGANISATION OF SYSTEMS

Thomas L. Saaty and Kevin P. Kearns

Pergamon Press, 1985. Price: U.S. $40.00, U.K. £29.50.

THE GEOGRAPHER AT WORK

Peter Gould

Routledge and Kegan Paul, London 1985’ Price: £8.95.

UTOPIA ON TRIAL

Alice Colman

Hilary Shipman Ltd., 19 Framfield Road, Highbury, London. May 1985 (reprinted August, 1985). Price: £7.95.

SIR RAYMOND UNWIN: ARCHITECT, PLANNER AND VISIONARY

Frank Jackson

A. Zwemmer Ltd., London 1985. 187 pp. with maps and illustrations.

STRATEGIC PLANNING IN ACTION: THE IMPACT OF THE CLYDE VALLEY REGIONAL PLAN 1946–1982

R. Smith and U. Wannop (eds)

Gower, 1985, 272 pp. Price: £16.50.

LOCALITIES, CLASS AND GENDER

The Lancaster Regionalism Group (Linda Murgatroyd, Mike Savage, Dan Shapiro, John Urry, Sylvia Walby, Alan Warde, with Jane Mark‐Lawson)

Pion Ltd., 1985. Price: £12.00.     

Evaluation of Olfactory Sensing in the Water Industry

On behalf of a consortium of water companies and manufacturers, an electronic olfactory sensor was evaluated for its potential application to on-line analysis within the water industry. Early results are encouraging. The sensor has the ability to detect contaminants in raw water which cause taste and odour problems, such as 2,4,6-trichloroanisole and some hydrocarbons. It can also discriminate between three different raw water sources.     

Wet deposition of mercury within the vicinity of a cement plant before and during cement plant maintenance

Hg species (total mercury, methylmercury, reactive mercury) in precipitation were investigated in the vicinity of the Lehigh Hanson Permanente Cement Plant in the San Francisco Bay Area, CA., USA. Precipitation was collected weekly between November 29, 2007 and March 20, 2008, which included the period in February and March 2008 when cement production was minimized during annual plant maintenance. When the cement plant was operational, the volume weighted mean (VWM) and wet depositional flux for total Hg (Hg_T) were 6.7 and 5.8 times higher, respectively, compared to a control site located 3.5 km east of the cement plant. In February and March, when cement plant operations were minimized, levels were approximately equal at both sites (the ratio for both parameters was 1.1). Due to the close proximity between the two sites, meteorological conditions (e.g., precipitation levels, wind direction) were similar, and therefore higher VWM Hg_T levels and Hg_T deposition likely reflected increased Hg emissions from the cement plant. Methylmercury (MeHg) and reactive Hg (Hg(II)) were also measured; compared to the control site, the VWM for MeHg was lower at the cement plant (the ratio = 0.75) and the VWM for Hg(II) was slightly higher (ratio = 1.2), which indicated the cement plant was not likely a significant source of these Hg species to the watershed.     

Modelling contra-flow in crowd dynamics DEM simulation

This paper highlights the growing need for a realistic crowd simulation in the design of large venues such as concert halls and stadia. A discrete element method (DEM) technique for modelling crowd dynamics has been developed that represents each person within the model as 3 overlapping circles, a position, orientation and velocity in 2D. Contact forces between elements are included in the model as well as psychological forces, motive forces and moments. The motion of each person is then modelled in a Newtonian manner with a numerical integration time-stepping scheme. The model has been shown previously to work well in predicting egress. In this paper the predicted model behaviour is compared to actual video footage shot at various locations around University Park Campus, Nottingham. It did not match well to the video footage when people are moving towards each other, as in cases of contra-flow on a walkway. In order to improve the model, a general algorithm for ‘avoidance’ was included which appeared to make the model significantly more realistic in these cases. The paper also shows areas for further potential development, such as incorporating people into associative groups such as family or friends.