Browsing by Author "O'Connor, Donald J."
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Item The Carbon-Oxygen Distribution In New York Bight(1979-08) O'Connor, Donald J.; Mancini, John L.Item A Dynamic Model of Phytoplankton Populations in Natural Waters(1970-06) DiToro, Dominic M.; O'Connor, Donald J.; Thomann, Robert V.Item Dynamic Water Quality Forecasting And Management(1973-08) O'Connor, Donald J.; Thomann, Robert V.; Di Toro, Dominic M.This report describes the formulation and initial verification of two modeling frameworks. The first is directed toward an analysis of the impact of the carbonaceous and nitrogenous components and wastewater on the dissolved oxygen resources of a natural water system. The second modeling framework concentrates on the interactions between the discharge of nutrient, both nitrogen and phosphorus, and the biomass of the phytoplankton ,and zooplankton populations which result, as well as incorporating the overall impact on dissolved oxygen. The models are formulated in terms of coupled differential equations which incorporate both the effect of transport due to tidal motion and turbulence, and the kinetics which describe the biological and chemical transformations that can occur. The modeling frameworks are applied to the Delaware and Potomac estuaries in order to estimate the ability of such models to describe the water quality effects of carbon, nitrogen, and phosphorous discharges. The agreement achieved between observation and calculation indicate that the major features of the impact of wastewater components on eutrophication phenomena can be successfully analyzed within the context of the model presented herein. This report was submitted in fulfillment of Project Number R800369, by Manhattan College, Bronx, New York, under the sponsorship of the Environmental Protection Agency. Work was completed as December 31, 1972.Item The Effect of Chemical & Physical Variables on Reaeration(1960-06) O'Connor, Donald J.Item Evaluation Of Factors Influencing The Temporal Variation Of Dissolved Oxygen In The New York Bight(1981-05) O'Connor, Donald J.; Mancini, John L.; Guerriero, Joanne R.Item Mathematical Modeling of Phytoplankton in Lake Ontario,Part 2 Simulations Using Lake 1 Model(Enviromental Protection Agency (EPA), 1976-08) Thomann, Robert V.; Winfield, Richard P.; Di Toro, Dominic M.; O'Connor, Donald J.The results of a series of simulations of the response of the open lake region of Lake Ontario to various levels of nutrient input are described in this report. The simulations use a simplified dynamic model of phytoplankton nutrient interactions in a vertically segmented structure. The lake is assumed to be well-mixed in the horizontal direction. The problem of long term simulations (10-20 years) that draw on short term observation and verification periods (5 years) is discussed and it is indicated that the overall loss rates of nutrient are of particular importance. Under a hypothesized, but reasonable, set of model parameters, the simulations indicate that the present observed open lake phytoplankton biomass of Lake Ontario does not appear to be in equilibrium with the present input nutrient load. Therefore, if the present load is continued, it is estimated that spring peak phytoplankton chlorophyll in the epilimnion will continue to increase to a new level about 45% higher than present levels. The interaction of nitrogen and phosphorus is also described by the simulations and the results indicate a tendency for nitrogen limitation to be an increasing dominant factor in controlling the spring bloom. A pastoral" simulation using load estimates, indicative of conditions prior to man's intensive activity provides an approximation of an early state of the lake. This "hindcast" indicates that spring phytoplankton levels were some 40% less than present levels and average annual epilimnion biomass under equilibrium with present loads is about twice that under pastoral conditions. A series of analyses is also conducted comparing simulations from the dynamic model to estimates made from simplified plots of loading versus lake geometry. The results from the dynamic model indicate that a reduction in external nutrient load does not result in an accompanying decrease in phytoplankton biomass, due to the hypothesized non-equilibrium condition of Lake Ontario. The dynamic model results are therefore in contrast to the results one would obtain from using "admissable" loading concept which indicates an improvement in lake trophic status. Analysis of lake response to the U.S.-Canada Water Quality Agreement (WQA) loads using the hypothesized parameters indicates about a 6% reduction in peak phytoplankton at equilibrium. The implications of the results appear to be of some importance since the analyses indicate that it may difficult to achieve measurable reductions below present levels of phytoplankton biomass in the open lake. From a decision and policy making viewpoint then, the simulations tend to indicate that maximum point source nutrient control for Lake Ontario will, at best, be a "ho1ding" action rather than a significant improvement in the status of the be open lake. This report was submitted in partial fulfillment of Grant Number R 800610 to the Environmental Engineering and Science Program, Manhattan College, Bronx, New York by the U.S. Environmental Protection Agency. Work was completed as of April, 1975.Item Mathematical Models Of Toxic Substances In Estuaries With Application to Kepone In The James River(1981-02) O'Connor, Donald J.; Farley, Kevin J.; Mueller, John A.The primary purpose of this research project is to develop the equations for modeling of toxic substances in estuaries and to demonstrate the application of these equations to present and anticipated problem areas. The present structure of the model is two-dimensional (longitudinal-vertical) interacting with lateral embayments which may operate in a steady-state or time-variable mode. The water column is segmented into two vertical layers to incorporate the typical estuarine circulation interacting with a bed which is also segmented into two layers - an active interfacial region and a deeper stationary bed. Adsorption-desorption kinetics are included which, in the case of the Kepone distribution of the James River, are assumed to be at equilibrium. Both steady-state, as well as time-variable, conditions were analyzed to calibrate the model to reproduce presently observed concentrations of Kepone. Sensitivity analyses and projections were conducted to estimate the time required to reduce the present level of contamination. In order to provide the necessary background for the development of the model, the various factors which affect the kinetic interactions of sorption and which affect the distributions of the suspended and bed solids are discussed in the introductory sections. This is followed by the development of a one-dimensional analysis, similar to the classical estuarine water quality equations in present use. This type of analysis may be used for preliminary assessment of a problem. An example of its application to the James River is included. A procedure of analysis to address the problem of organic chemicals in estuaries has been structured. The procedure involves a series of analytical and computational steps, relating to the fluid transport, the solids distribution and the concentrations of the organic chemical in the water and the bed. Each step involves the determination or assignment of the appropriate transport, transfer and/or reaction coefficients to analyze a particular constituent of the system. Equally important, each step provides the input for the computation of the next element, for which an additional coefficient is required. The analysis proceeds in a sequence of increasing complexity, each element yielding a calibration or validation of an essential constituent. The final output is the temporal or spatial distribution of the organic chemical. Specific recommendations are presented relating to further calibration and validation of these models in other estuaries. Particular attention should be directed to an assessment of the inputs, characterization of bed conditions and evaluation of kinetic interactions. It is planned to incorporate these factors in ongoing research.Item Water Quality(The Sea Grant Institute of SUNY and Cornell University, 1977-10) O'Connor, Donald J.; Thomann, Robert V.; Salas, Henry J.This monograph describes the water quality of New York Bight as measured by temperature, light, salinity, dissolved oxygen, various nitrogen and phosphorus forms, pH, heavy metals, coliform bacteria, and phytoplankton chlorophyll. Major water quality monitoring in the Bight, initiated in 1948, has been sporadic in the past with gaps from 3 to 10 years when no major sampling was conducted. These data indicate that bottom dissolved oxygen percent saturation levels in the disposal areas of the apex have decreased from 67% in 1949 to 30% in 1974. Surface total iron concentrations in the apex have increased from 20 u/l in 1949 to about 90 u/l in 1969, and are higher than background open ocean levels. Coliform bacterial influence appears to be confined to an area of 3.2 to 4.8 km (2 to 3 mi) radius from the discharge point of a sewage sludge barge dump. Nitrogen is generally the more important nutrient relative to phosphorus with respect to limiting phytoplankton growth in the Bight. Man’s impact on the water quality of the region appears to be significant with more than 50% of the total input of iron, copper, cadmium, chromium, suspended solids, and total phosphorus attributed to barge discharges alone. An overall analysis of New York Bight to quantitatively assess the relative impact of the major discharges is recommended.