Role of Effluent Permit Trading in Total Maximum Daily Load Programs: Overview and Uncertainty and Reliability Implications

Many jurisdictions in the United States are currently preparing total maximum daily load (TMDL) programs for stream segments that come under Section 303(d) of the Clean Water Act. Among the options being considered by many state pollution control agencies is that of permit trading, otherwise known as permit transfers, transferable permits, emissions trading, bubbles, pollution rights, marketable effluent permits, and transferable discharge permits. Under such programs, a permit to discharge into a watercourse, issued as part of a wasteload allocation program, is treated as a marketable commodity. This paper presents a qualitative discussion of the strengths and weaknesses of permit trading in the context of a TMDL program, and discusses the circumstances that favor it. The paper also presents hypothetical quantitative findings to illustrate the circumstances under which a regional administrator might wish to adopt a program of permit trading, and if so, what type of permits would suit it best.     

Perspectives on U.S. Great Lakes Chemical Toxic Substances Research

Because of their magnitude, their geographic and demographic characteristics, and their unique limnological properties, the Great Lakes appear to be especially susceptible to chemical contamination. The scientific basis for dealing with this contamination is very limited compared with the magnitude of the problem. This is particularly evident when the vast array of toxic xenobiotic substances of anthropogenic origin are considered. Major knowledge gaps exist on the critical transport pathways, ultimate fate, and ecological effects of toxic substances (of urgent importance are health effects on humans residing in the basin), as well as on the economic and social aspects of toxics management.The economic climate of the 1980s, however, is likely to severely limit the resources available for the conduct of research which is so badly needed. Consequently, it appears that the Great Lakes research community will have imposed upon it a markedly increased demand for information and a concomitant reduction in the resources available to accomplish the task. Finally, despite a pessimistic outlook for research support, there is optimism that the Great Lakes will respond positively, and in a relatively short time span (years as opposed to centuries), to the abatement of toxic inputs. Nevertheless, additional information on the processes affecting the distribution and fate of toxic substances is still critical to the understanding required to ensure effective remedial actions.     

Numerical fluorescence correlation spectroscopy for the analysis of molecular dynamics under nonstandard conditions

The suitability of mathematical models used to extract kinetic information from correlated data constitutes a significant issue in fluorescence correlation spectroscopy (FCS). Standard FCS equations are derived from a simple Gaussian approximation of the optical detection volume, but some investigations have suggested this traditional practice can lead to inaccurate and misleading conclusions under many experimental circumstances, particularly those encountered in one-photon confocal measurements. Furthermore, analytical models cannot be derived for all measurement scenarios. We describe a novel numerical approach to FCS that circumvents conventional analytical models, enabling meaningful analyses even under extraordinarily unusual measurement conditions. Numerical fluorescence correlation spectroscopy (NFCS) involves quantitatively matching experimental correlation curves with synthetic curves generated via diffusion simulation or direct calculation based on an experimentally determined 3D map of the detection volume. Model parameters are adjusted iteratively to minimize the residual differences between synthetic and experimental correlation curves. In order to reduce analysis time, we distribute calculations across a network of processors. As an example of this new approach, we demonstrate that synthetic autocorrelation curves correspond well with experimental data and that NFCS diffusion measurements of Rhodamine B remain constant, regardless of the distortion present in a confocal detection volume.     

Factors influencing legacy pollutant accumulation in alpine osprey: biology, topography, or melting glaciers?

Persistent organic pollutants (POPs) can be transported long distances and deposited into alpine environments via cold trapping and snow scavenging processes. Here we examined biotic and abiotic factors determining contaminant variability of wildlife in alpine ecosystems. We measured POPs in eggs and plasma of an apex predator, the osprey (Pandion haliaetus) breeding in 15 mountainous watersheds across a broad latitudinal, longitudinal and altitudinal range in western Canada. After accounting for proximate biotic factors such as trophic level (δ(15)N) and carbon source (δ(13)C), variability in contaminant concentrations, including ΣDDT (sum of trichlorodiphenylethane-related compounds), toxaphene, hexachlorobenzene (HCB), total chlordane, and ΣPCBs (polychlorinated biphenyls) in osprey tissues was explained by interactions among relative size of watersheds, water bodies, elevation, and glacial input. ΣDDT in nestling plasma, for example, decreased with lake elevation, probably as a result of local past inputs from agricultural or public health usage at lower altitude sites. In contrast, toxaphene, never used as an insecticide in western Canada, increased with elevation and year-round snow and ice cover in both plasma and eggs, indicating long-range atmospheric sources as dominant for toxaphene. Lower chlorinated PCBs in plasma tended to decrease with elevation and ice cover consistent with published data and model outcomes. Temporal trends of POPs in osprey eggs are coincident with some modeled predictions of release from melting glaciers due to climate change. Currently we suggest that contaminants largely are released through annual snowpack melt and deposited in large lower elevation lakes, or some smaller lakes with poor drainage. Our study highlights the importance of understanding how biological processes integrate physical when studying the environmental chemistry of wildlife.     

Aphasic patients' sensitivity to structural and meaning violations when monitoring for nouns and verbs in sentences.

Aphasic patients with and without impairment of semantically reversible sentence comprehension and 2 groups of normal controls were monitored for unambiguous noun or verb targets while listening to sentence pairs. Four conditions of target-word/sentence-pair congruence were created by manipulating the predictability of the target word from a context sentence and by inserting targets into structures that were appropriate or inappropriate for the target's grammatical class. Normal and aphasic listeners showed comparable sensitivity to structural violations under different conditions of semantic predictability, and there was little difference in the performance of aphasic patients with and without comprehension disorder. These results support the argument that normal sensitivity to syntactic requirements can be found in patients with reversible sentence comprehension disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of surface features on word-fragment completion in amnesic subjects

This study compared 40 female participants in a behavioral weight loss program who frequently reported craving sweets to 40 who rarely reported craving sweets using 2-week behavioral eating diaries. The two groups were compared on physiological, demographic, and questionnaire measures and no significant differences were found. There were no significant differences in macronutrient intake either overall or in a wide range of specific situations. The relative proportions of carbohydrate, protein, and fat consumed in association with craving sweets differed only slightly from the composition of other meals and snacks. Carbohydrate and protein intake when craving sweets was similar to breakfasts while the relative amount of fat consumed when craving sweets was comparable to episodes of overeating. The two groups differed in their reporting of moods with the high-craving group reporting more boredom and less stress than the low-craving group. The relationship between situational and mood variables and reports of craving sweets did not differ between the two groups. Craving sweets was negatively associated with hunger and was not associated with meal skipping. A sequential analysis demonstrated that eating in response to craving sweets triggers an abstinence violation effect. These data are not consistent with the hypothesis that sweet craver's consume high-carbohydrate, low-protein meals and snacks in order to self-medicate depression caused by serotonin depletion. Instead, the data suggest that we should further explore the role of food palatability and food-related cognitions in order to understand craving sweets.     

Residential response to critical-peak pricing of electricity: California evidence

This paper analyzes data from 483 households that took part in a critical-peak pricing (CPP) experiment between July and September 2004. Using a regression-based approach to quantify hourly baseline electric loads that would have occurred absent CPP events, we show a statistically significant average participant response in each hour. Average peak response estimates are provided for each of twelve experimental strata, by climate zone and building type. Results show that larger users respond more in both absolute and percentage terms, and customers in the coolest climate zone respond most as a percentage of their baseline load. Finally, an analysis involving the two different levels of critical-peak prices – $0.50/kWh and $0.68/kWh – indicates that households did not respond more to the higher CPP rate.     

Some numerical properties of explicit solutions to the one‐dimensional conservation equation

Abstract:

One‐dimensional unsteady‐state advection‐dispersion models are useful in practice for predicting time‐varying concentrations in streams for phenomena such as chemical spills or combined sewer overflows. The challenge in modeling such phenomena, which demonstrate sharp concentration gradients, is to ensure that the numerical dispersion, an artificial erroneous smearing of concentrations, not overshadow the true dispersion, which, while of significance due to sharp gradients, is ordinarily small compared to advection as a transport mechanism. This paper revisits stability criteria and numerical dispersion properties of explicit Lagrangian and Eulerian solutions of the one‐dimensional advection‐dispersion equation. It is shown that the Leith method of correcting for numerical dispersion (which was developed prior to the recent increase in popularity of Lagrangian methods) has similar stability restrictions on the step sizes as the latter when the zero‐overshoot criterion for stability is used. For uncorrected Eulerian formulations, the stable regions for Dx and Dt depend on the approximation of the advection term. For the forward and central difference approximations, the region is bounded, while for the backward difference formulation, Dx is unbounded. For Lagrangian formulations, the stable region has no upper bound, but has a lower bound on Dx. Correcting numerical dispersion in Eulerian formulations not only results in substantially better accuracy but changes the stable regions for Dx and Dt. The stable regions for corrected Eulerian formulations ‐ indeed, the formulations themselves ‐ are independent of the type of approximation of the first derivative, and are unbounded, although they become increasingly narrow as the true dispersion decreases. As the true dispersion approaches zero, the stable region approaches a line which corresponds to a Courant number of one. Thus, in the limit where the dispersion approaches zero, corrected Eulerian formulations, like Lagrangian formulations, must use a Courant number of one, but corrected Eulerian formulations do not have the lower bound on step size.