Endogenous Timing in Pollution Control: Stackelberg versus Cournot-Nash Equilibria

27 p.

An economic air pollution control model-application : photochemical smog in Los Angeles County in 1975

An economic air pollution control model, which determines the least cost of reaching various air quality levels, is formulated. The model takes the form of a general, nonlinear, mathematical programming problem. Primary contaminant emission levels are the independent variables. The objective function is the cost of attaining various emission levels and is to be minimized subject to constraints that given air quality levels be attained.

The model is applied to a simplified statement of the photochemical smog problem in Los Angeles County in 1975 with emissions specified by a two-dimensional vector, total reactive hydrocarbon, (RHC), and nitrogen oxide, (NO_x), emissions. Air quality, also two-dimensional, is measured by the expected number of days per year that nitrogen dioxide, (NO₂), and mid-day ozone, (O₃), exceed standards in Central Los Angeles.

The minimum cost of reaching various emission levels is found by a linear programming model. The base or "uncontrolled" emission levels are those that will exist in 1975 with the present new car control program and with the degree of stationary source control existing in 1971. Controls, basically "add-on devices", are considered here for used cars, aircraft, and existing stationary sources. It is found that with these added controls, Los Angeles County emission levels [(1300 tons/day RHC, 1000 tons /day NO_x) in 1969] and [(670 tons/day RHC, 790 tons/day NO_x) at the base 1975 level], can be reduced to 260 tons/day RHC (minimum RHC program) and 460 tons/day NO_x (minimum NO_x program).

"Phenomenological" or statistical air quality models provide the relationship between air quality and emissions. These models estimate the relationship by using atmospheric monitoring data taken at one (yearly) emission level and by using certain simple physical assumptions, (e. g., that emissions are reduced proportionately at all points in space and time). For NO₂, (concentrations assumed proportional to NO_x emissions), it is found that standard violations in Central Los Angeles, (55 in 1969), can be reduced to 25, 5, and 0 days per year by controlling emissions to 800, 550, and 300 tons /day, respectively. A probabilistic model reveals that RHC control is much more effective than NO_x control in reducing Central Los Angeles ozone. The 150 days per year ozone violations in 1969 can be reduced to 75, 30, 10, and 0 days per year by abating RHC emissions to 700, 450, 300, and 150 tons/day, respectively, (at the 1969 NO_x emission level).

The control cost-emission level and air quality-emission level relationships are combined in a graphical solution of the complete model to find the cost of various air quality levels. Best possible air quality levels with the controls considered here are 8 O₃ and 10 NO₂ violations per year (minimum ozone program) or 25 O₃ and 3 NO₂ violations per year (minimum NO₂ program) with an annualized cost of $230,000,000 (above the estimated $150,000,000 per year for the new car control program for Los Angeles County motor vehicles in 1975).

Mathematical models for the prediction of temperature distributions resulting from the discharge of heated water into large bodies of water

Mathematical models for heated water outfalls were developed for three flow regions. Near the source, the subsurface discharge into a stratified ambient water issuing from a row of buoyant jets was solved with the jet interference included in the analysis. The analysis of the flow zone close to and at intermediate distances from a surface buoyant jet was developed for the two-dimensional and axisymmetric cases. Far away from the source, a passive dispersion model was solved for a two dimensional situation taking into consideration the effects of shear current and vertical changes in diffusivity. A significant result from the surface buoyant jet analysis is the ability to predict the onset and location of an internal hydraulic jump. Prediction can be made simply from the knowledge of the source Froude number and a dimensionless surface exchange coefficient. Parametric computer programs of the above models are also developed as a part of this study. This report was submitted in fulfillment of Contract No. 14-12-570 under the sponsorship of the Federal Water Quality Administration.

Algae and water pollution in Mahi Estuary

Distribution of phytoplankton, chlorophyll A and phaeophytin was studied at different locations in the Mahi Estuary, Gujarat, India during 1982. The water quality at the discharge point was poor while the region away from it was relatively unpolluted. The results indicated a wide range of variation in phytoplankton population (7.68-5010, 96 x 10 super(4) cells/l, chl. a 2.22-58.22 mg/m super(3) and phaeophytin [0.20-10.21 mg/m super(3)]. The ratio of chl. a/phaeophytin were remarkably low at highly polluted stations. Higher abundance of the genera Oscillatoria and Nitzschia were recorded at polluted stations. The diversity of species at the unpolluted station was higher (1.56) as compared to the polluted station (1.07).

Effects of seasonal succession and water pollution on the protozoan community structure in an eutrophic lake

The purpose of the research is to study the seasonal succession of protozoa community and the effect of water quality on the protozoa community to characterize biochemical processes occurring at a eutrophic Lake Donghu, a large shallow lake in Wuhan City, China. Samples of protozoa communities were obtained monthly at three stations by PFU (polyurethane foam unit) method over a year. Synchronously, water samples also were taken from the stations for the water chemical quality analysis. Six major variables were examined in a principal component analysis (PCA), which indicate the fast changes of water quality in this station I and less within-year variation and a comparatively stable water quality in stations II and III. The community data were analyzed using multivariate techniques, and we show that clusters are rather mixed and poorly separated, suggesting that the community structure is changing gradually, giving a slight merging of clusters form the summer to the autumn and the autumn to the winter. Canonical correspondence analysis (CCA) was used to infer the relationship between water quality variables and phytoplankton community structure, which changed substantially over the survey period. From the analysis of cluster and CCA, coupled by community pollution value (CPV), it is concluded that the key factors driving the change in protozoa community composition in Lake Donghu was water qualities rather than seasons. (c) 2006 Elsevier Ltd. All rights reserved.

A microbiological survey of a constructed wetland system supplied by dairy 'dirty water' effluent

A constructed wetland at Greenmount College, Co. Antrim, N. Ireland was built in 2004 to study the treatment of ‘dirty water’ effluent from the Greenmount dairy unit. The effluent has a mean BOD5 of c.1000 mg/L and contains milking parlour wash-water and runoff from silage clamps and yard areas lightly contaminated with cattle manure. The nominal water retention time of this wetland is 100 days. The primary purposes of the wetland are to eliminate organic pollution and eutrophication risk from nitrogen and phosphorus compounds. However the wetland should also effectively remove any zoonotic pathogens present in manure and milk. Accordingly, a 12-month microbiological survey of water in the five ponds of the wetland commenced in August 2007. The aims of the survey are to determine changes, as effluent passes through the wetland system, in a broad range of indicator organisms (faecal coliforms, Escherichia coli, Enterococcus faecalis and Clostridium perfringens) and the occurrence of several pathogens - Salmonella, Campylobacter, Cryptosporidium and Mycobacterium avium subsp. paratuberculosis (Map). The highest indicator organism counts - E. coli and faecal coliforms, 103-104 CFU/ml - are observed in pond 1, and a significant reduction (1-3 log10) in all indicator organisms occurs as water passes through the wetland from pond 1 to pond 5. Hence the wetland is efficient at reducing levels of indicator organisms in the dairy effluent. Salmonella and Campylobacter spp. are being detected intermittently in all the ponds, whilst Cryptosporidium and Map have yet to be detected, and so the ability of the wetland to reduce/eliminate specific pathogens is less clear at present.

Electrodialytic remediation of two types of air pollution control residues and their applicability in construction materials

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente Perfil de Engenharia de Sistemas Ambientais