A note on natural production functions

Two techniques are presented for estimation of natural animal populations, both of which may incorporate the effect of pollutants on populations. Both techniques assume specific underlying population dynamics which may not be applicable to certain species or ecosystems. However, both techniques allow for testing the hypothesis that the population dynamics specified is applicable. The techniques are used to criticize two recent empirical investigations of fisheries.     

Intertemporal and intergenerational pareto efficiency: A comment

In a recent issue of this Journal, Sandler and Smith developed an analysis from which they concluded that discounting is Pareto inefficient in an intertemporal context. This comment questions the validity of that conclusion and demonstrates the essential role played by the discount rate in achieving intertemporal Pareto efficiency within a market economy.     

Bereavement and mourning after a shipping disaster: The case for intervention

This paper describes the help given by the social services department of a shipping company to bereaved families following a shipping disaster. In the absence of clear, factual and prompt information from an authoritative source, there is a tendency for bereaved individuals to deny their loss and thereby delay the process of mourning and eventual recovery. Appropriate intervention and support can help to overcome this tendency as was seen in the Madasa case.     

The 1934 floods in Tabriz, N. W. Iran

The disastrous floods of July 1934 in Tabriz are examined in the context of the history of floodinginthe city, which is crossed by a dry stream bed liable to sudden Inundation by mountain torrents from the southeast. Few details of past events have survived, suggesting that relatively little significance has been attached to them. Typically, flood dykes were inadequately maintained. This neglect, combined with a radical alteration in urban topography after 1925, when broad straight avenues were constructed through the old heart of the city, led to serious losses from flooding twice in 1929 and again in 1934. Enhanced perception of the flood risk finally found expression in the adoption of large scale engineering measures to mitigate future events, including strengthening protective dykes and widening the river channel through the city. These works have reduced vulnerability to flooding from river overflow. No long-term detrimental Impact of the 1934 flood has been observed. Some of the physical and social parameters that have influenced the vulnerability of Tabrizinthe past continue to be present both there and elsewhere in Iran, and they may be characteristic also of other regions with comparable natural environments or in a similar stage of socio-economic development.     

A model for positive environmental control

In the control of pollution, two apparently important facts are often negelected: (1) removal of a particular pollutant from a particular source and location may merely result in transforming it into a pollutant, or pollutants of different forms, in other locations; (2) the activity of pollution control itself requires inputs, the production of which may generate additional pollutants. In order to achieve positive environmental control, these two facts must be considered in selecting control processes and in determining optimum control standards. It is necessary that an integrated approach to pollution control be taken, making allowances for ecological inter-relations. As practiced today, pollution control is handled as separate problems of disposing gas, liquid and solid wastes. This paper proposes a model for evaluating the total environmental impact of a pollution control process or method. Theoretical criteria for determining an optimum control level with or without resource constraint are also derived.     

Mobility control: How injected surfactants and biostimulants may be forced into low‐permeability units

Recovering dense nonaqueous‐phase liquid (DNAPL) remains one of the most difficult problems facing the remediation industry. Still, the most common method of recovering DNAPL is to physically remove the contaminants using common technologies such as total fluids recovery pumps, vacuum systems, and “pump‐and‐treat.” Increased DNAPL removal can be attained using surfactants to mobilize and/or solubilize the pollutants. However, very little is understood of the methods developed by petroleum engineers beginning in the 1960s to overcome by‐passed, low‐permeability zones in heterogeneous oil reservoirs. By injecting or causing the formation of viscous fluids in the subsurface, petroleum engineers caused increased in‐situ pressures that forced fluid flow into low permeability units as well as the higher permeability thief zones. Polymer flooding involves injecting a viscous aqueous polymer solution into the contaminated aquifer. Foam flooding involves injecting surfactant to decontaminate the high‐permeability zones and then periodic pulses of air to cause a temporary viscous foam to form in the high‐permeable zones after all DNAPL is removed. Later surfactant pulses are directed by the foam into unswept low‐permeable units. These methods have been applied to DNAPL removal using surfactants but they can also be applied to the injection of bio‐amendments into low‐permeability zones still requiring continued remediation. Here we discuss the principles of mobility control as practiced in an alluvial aquifer contaminated with chlorinated solvent and coal tar DNAPLs as well as some field results. © 2003 Wiley Periodicals, Inc.     

The use of enhanced bioremediation at the Savannah River Site to remediate pesticides and PCBs

Enhanced bioremediation is quickly developing into an economical and viable technology for the remediation of contaminated soils. Until recently, chlorinated organic compounds have proven difficult to bioremediate. Environmentally recalcitrant compounds, such as polychlorinated biphenyls (PCBs) and persistent organic pesticides (POPs) such as dichlorodiphenyl trichloroethane (DDT) have shown to be especially arduous to bioremediate. Recent advances in field‐scale bioremedial applications have indicated that biodegradation of these compounds may be possible. Engineers and scientists at the Savannah River Site (SRS), a major DOE installation near Aiken, South Carolina, are using enhanced bioremediation to remediate soils contaminated with pesticides (DDT and its metabolites, heptachlor epoxide, dieldrin, and endrin) and PCBs. This article reviews the ongoing remediation occurring at the Chemicals, Metals, and Pesticides (CMP) Pits using windrow turners to facilitate microbial degradation of certain pesticides and PCBs. © 2003 Wiley Periodicals, Inc.     

Pilot‐scale demonstration of in situ capping of PCB‐containing sediments in the lower Grasse River

A fish‐consumption advisory is currently in effect in a seven‐mile stretch of the Grasse River in Massena, New York, due to elevated levels of PCBs in fish tissue. One remedial approach that is being evaluated to reduce the PCB levels in fish from the river is in situ capping. An in‐river pilot study was conducted in the summer of 2001 to assess the feasibility of capping PCB‐containing sediments of the river. The study consisted of the construction of a subaqueous cap in a seven‐acre portion of the river using various combinations of capping materials and placement techniques. Optimal results were achieved with a 1:1 sand/topsoil mix released from a clamshell bucket either just above or several feet below the water surface. A longer‐term monitoring program of the capped area commenced in 2002. Results of this monitoring indicated: 1) the in‐place cap has remained intact since installation; 2) no evidence of PCB migration into and through the cap; 3) groundwater advection through the cap is not an important PCB transport mechanism; and 4) macroinvertebrate colonization of the in‐place cap is continuing. Additional follow‐up monitoring in the spring of 2003 indicated that a significant portion of the cap and, in some cases, the underlying sediments had been disturbed in the period following the conclusion of the 2002 monitoring work. An analysis of river conditions in the spring of 2003 indicated that a significant ice jam had formed in the river directly over the capping pilot study area, and that the resulting increase in river velocities and turbulence in the area resulted in the movement of both cap materials and the underlying sediments. The pilot cap was not designed to address ice jam–related forces on the cap, as the occurrence of ice jams in this section of the river had not been known prior to the observations conducted in the spring of 2003. These findings will preclude implementation of the longer‐term monitoring program that had been envisioned for the pilot study. The data collected immediately after cap construction in 2001 and through the first year of monitoring in 2002 serve as the basis for the conclusions presented in this article. It should be recognized that, based on the observation made in the spring of 2003, some of these conclusions are no longer valid for the pilot study area.The occurrence of ice jams in the lower Grasse River and their importance on sediments and PCBs within the system are currently under investigation. © 2003 Wiley Periodicals, Inc.