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Presentation Abstracts
Title: Modeling Sediment Phosphorus Flux for Onondaga Lake
Authors:
Gilbert N. Lewis
Department of Mathematical Sciences
Michigan Technological University
Houghton, MI 49931
Martin T. Auer
Department of Civil & Environmental Engineering, Michigan Technological University
Houghton, MI 49931
Xinyu Xiang
Department of Applied Mathematics and Statistics
State University of New York at Stony Brook
Michael R. Penn
Department of Civil Engineering
University of Wisconsin – Platteville
Abstract: While reductions in external phosphorus inputs to lakes have, in some cases, resulted in changes in trophic state and concomitant improvements in water quality, there are other instances where internal loads have retarded the lake response. The persistence of eutrophic conditions following implementation of management actions lies in conflict with public expectations relating to lake restoration programs. Onondaga Lake has received excessive phosphorus inputs for decades and the lake's sediment are enriched with labile forms of this nutrient. The accumulation of soluble phosphorus in the lake's hypolimnion each summer, to levels exceeding 1000 µg·L-1, is one of the most striking features of this system's limnology.
Here we take advantage of a series of field and laboratory measurements of phosphorus deposition, diagenesis, and release conducted on Onondaga Lake to develop and test a model of sediment phosphorus flux. The model is based on the principles of sediment diagenesis and tracks the fate of labile phosphorus in time and space following deposition. Simply stated, labile phosphorus is deposited at the sediment surface and moves through the sediment profile, undergoing diagenesis to soluble phosphorus which is subsequently released to the overlying water. The model is calibrated to measured sediment profiles of labile particulate and soluble phosphorus by adjustment of coefficients. Capricious calibration decisions are avoided by maintaining coefficient adjustment within their observed range of variation and by requiring that both solid and liquid phases be suitably fit. The model is then validated by comparing the resultant release rates to field measurements with no further coefficient adjustment. Lastly, the validated model is applied to establish the timing of system response to reduction in external loads. It is found that sediment release rates come into steady state with the new loading regime in a time frame on the order of decades. This, in marked contrast to the water column response which occurs in months. The significance of these findings to lake management will be discussed.
Title: Impacts of a Soda Ash Facility on Onondaga Lake and the Seneca River, Revisited
Authors:
Steve W. Effler and David A. Matthews
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Abstract: A synthesis of the impacts of the operation (1884 - 1986) of a soda ash (Na2CO3) manufacturing facility on Onondaga Lake, NY, its tributaries, and adjoining portions of the river that receives the lake's outflow is presented, based on long-term programs of monitoring, process studies, and mathematical modeling. The lake was used as a source of cooling water and for the disposal of ionic (Cl-, Na+, and Ca2+) waste, related solids and spent cooling water. At peak production the facility discharged ~ 1.3 x 106 metric tons of ionic waste to the lake annually. The soda ash facility had a profound impact on these ecosystems, by severely altering their structure and function. Portions of the two largest tributaries to the lake have been degraded from solids deposition associated with solution mining for NaCl (process reactant) and precipitation of Ca2+ waste (as CaCO3). The cooling water operation recycled phosphorus enriched hypolimnetic waters to productive layers. Ionic waste impacts on the lake and river included: (1) high salinity (S ~ 3 ‰), (2) plunging inflows made dense by high S, that altered fundamental features of the lake's stratification regime, (3) S-based density stratification and severe DO depletion over a 16 km reach of the river, (4) high levels of CaCO3 precipitation that reduced clarity, increased net sedimentation in pelagic areas, altered the character of near-shore sediments, reduced alkalinity, and reduced pH. These impacts on the lake chemistry and physical properties had profound effects on biological communities, including: (1) altered compositions, (2) reduced diversity, (3) limited macrophyte occurrence, (4) enhanced phytoplankton production, and (5) limited effectiveness of zooplankton grazing, thereby preventing intervals of high clarity. Closure of the facility resulted in dramatic improvements in water quality and ecological characteristics of these systems. Yet further improvement will occur as residual ionic waste loads decrease.
Title: An Upwelling Event at Onondaga Lake, NY: Characterization, Impact and Recurrence
Authors:
Bruce A. Wagner, Susan M. Doerr O'Donnell, David A. Matthews,
Carol M. Matthews, Rakesh K. Gelda, and Steven W. Effler
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
David M. O'Donnell
Innovative Engineering & Technology
Dewitt, NY. 13214
Edwin A. Cowen
Department of Civil and Environmental Engineering Cornell University
Ithaca, NY 14853-3501
Abstract:
The occurrence, features and impacts on oxygen resources of an upwelling event in culturally eutrophic Onondaga Lake, NY, are documented, and recurrence is investigated, based on data collected as part of long-term, robotic, and event monitoring programs. The upwelling event occurred on September 11, 2002, in response to a wind event of average wind speed of ~ 10 m s-1 that extended over an interval of 11 hours along the main axis of the lake. Longitudinal differences in temperature (T) and dissolved oxygen (DO) documented for the lake's surface waters during the upwelling event were 5.7 ºC and 10 mg L-1. DO concentrations < 1 mg L-1 were observed in surface waters at the windward end of the lake. Oxidation of reduced oxygen-demanding by-products of anaerobic metabolism supplied to the upper waters from stratified layers during the event contributed to a loss of DO from the lake. Review of historic lake stratification, water quality related to oxygen resources, and long-term wind data indicate upwelling events with coupled deleterious impacts on DO resources have not been rare; at least 14 such events are estimated to have occurred over the 1990 - 2002 interval. The documented event probably represents a worst case for oxygen impacts for this period. An underway rehabilitation program, that will reduce anthropogenic phosphorus loading and implement hypolimnetic oxygenation, may ameliorate the impacts of upwelling events on the DO resources of the lake.
Title: Application of a Probabilistic Ammonia Model: Identification of Important Model Inputs and Critique of a TMDL Analysis for Onondaga Lake
Authors:
Rakesh K. Gelda and Steven W. Effler
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Abstract: Modeling analyses are conducted with a probabilistic mass balance ammonia model to demonstrate the important role specifications of model inputs and toxicity standards by regulators can play in determining the assimilative capacity of polluted Onondaga Lake, NY, and to support a critical review of a related Total Maximum Daily Load (TMDL) analysis. More than 90% of the ammonia received by the lake is from a municipal wastewater treatment plant (Metro). Decisions to be made by regulators in management applications of the model regarding several factors were found to greatly influence the lake's assimilative capacity (TMDL), including effects of: (1) anticipated hypolimnetic oxygenation treatment, (2) previously documented in-lake nitrification events, (3) residual industrial pollution on pH, (4) uncertainties and potential bias in pH measurements, (5) anticipated increases in population growth served by Metro, and (6) revisions in national guidance toxicity criteria prepared by the U. S. Environmental Protection Agency. Several limitations in the existing ammonia TMDL analysis are reported, including: (1) arbitrary specification of critical conditions, (2) omission of the important features of duration and allowable number of occurrences in the state standard, (3) identification of the wrong month as critical for the lake's assimilative capacity, (4) lack of recognition of the artificial assimilative capacity associated with the effects of residual industrial pollution, (5) the specified "margin of safety" was too low, given the level of modeling and input uncertainties, (6) anticipated increases in discharge from Metro were not considered, and (7) incorrect identification of the critical year for tributary hydrology. Recommendations are made to upgrade the ammonia TMDL analysis and supporting model framework and data sets.
Title: A Modeling Evaluation of METRO Effluent Discharge Scenarios
Authors:
Daniel K. Rucinski and Martin T. Auer
Department of Civil & Environmental Engineering, Michigan Technological University
Houghton, MI 49931
Steven W. Effler, Rakesh K. Gelda, and,
Susan M. Doerr O'Donnell
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Abstract: Manifestations of degraded water quality in culturally eutrophic Onondaga Lake, NY, include severe phytoplankton blooms, poor clarity, hypolimnetic oxygen depletion and subsequent accumulation of reduced species in the hypolimnion. This degradation is clearly linked to excessive phosphorus (P) loads, the greatest portion of which is delivered by the Metropolitan Syracuse Wastewater Treatment Plant (METRO). Several restoration plans have been proposed for this system, including diversion of the METRO effluent to the adjoining Seneca River. Plans for effluent diversion were abruptly abandoned when zebra mussel invasion of the river reduced dissolved oxygen levels and the assimilative capacity of the river in the critical summer months. However, the river's ability to assimilate the METRO effluent, in the presence of zebra mussels, was never quantified. Here we make use of validated mathematical models to further examine the diversion option and the complex interplay of lake and river conditions.
A total phosphorus model for Onondaga Lake and a dissolved oxygen model for the Seneca River are employed in an integrated fashion to quantify the feasibility of several management alternatives for lake rehabilitation. We extend the analysis to include a dual discharge option, i.e. partitioning of the effluent between the lake and river, to take advantage of seasonal variability in assimilative capacity, and the differing response characteristics of lake and river systems. Effluent routing in the module is accomplished through a software module termed the RiverMaster. Here, the effluent is routed, in whole or in part, to the lake or river in response to observed water quality conditions in the receiving waters. Model runs will be presented comparing the efficacy of diversion compared and advanced waste treatment and the role of other management options (e.g. nonpoint source control, limitation of sediment flux, hypolimnetic discharge, and river de-stratification) in meeting water quality objectives considered.
Title: Impact of the Fishing Derbies on Gasoline in Onondaga Lake
Authors:
John P. Hassett, Armando D. Avallone,
Karen A. Galvan, and Rebecca A. Lonergan
Chemistry Department, College of Environmental Science and Forestry,
State University of New York,
Syracuse, New York, 13210
Abstract: Although Onondaga Lake is chronically contaminated with some compounds found in gasoline, patterns indicate that gasoline is typically not the source of these compounds. However, during the Fishing Derbies of 2001 and 2002, concentrations of these compounds increased 4-10 fold and a clear gasoline pattern was observed. The increased concentrations indicated that several hundred gallons of gasoline were discharged into the lake. This excess contamination disappeared within one week and was not observed below the thermocline. These results indicate that gasoline contamination of the lake increases with increased use of it for recreational boating, as is observed in other regional lakes.
Title: Mercury Dynamics in Onondaga Lake
Authors:
Charles W. Sharpe
currently at O'Brien & Gere Engineers, Inc.
Syracuse, NY 13221
Charles T. Driscoll
Department of Civil and Environmental Engineering Syracuse University
Syracuse, NY 13210
Abstract:The sediments and fish in Onondaga Lake have been contaminated by historical inputs of mercury from a former chlor-alkali facility. The objective of this study was to investigate the dynamics and fate of mercury (Hg) in Onondaga Lake, NY and adjacent wetlands in 2000. The investigation of Onondaga Lake focused on the temporal patterns and concentrations of total and methyl Hg (MeHg) concentrations in the water column, settling particles, and sediments. These values together with data from previous studies were utilized to create mass balances for total Hg (HgT) and MeHg to quantify the fate of Hg inputs to the lake. The adjacent wetlands were studied to characterize the temporal patterns of water concentrations of HgT and MeHg.
Total Hg concentrations in the water column of Onondaga Lake ranged from 1.4 to 17.5 ng·L-1, with MeHg ranging from below the detection limit to 11.9 ng·L-1. Peak concentrations of HgT and MeHg were observed below the thermocline during the stratified period (June through October). During fall mixing, there were elevated HgT concentrations throughout the water column, with an average concentration of 13.4 ng/L. The mechanism responsible for this increase during fall is not evident.
Based on the mass balance for HgT, there was a six-fold increase between the input flux and sedimentation flux (2.24 vs. 12.3 mg·m-2·d-1) of Hg, indicating an additional source of HgT to the water column of Onondaga Lake. Resuspension of sediments from the pelagic and littoral zones was determined to provide an insignificant flux of Hg. The most likely source of Hg inputs would seem to be an ongoing external source (i.e., ground water) that has not been previously been reported. Loss of HgT occurred predominantly through sediment burial (12.8 mg·m-2·d-1). Onondaga Lake is also a significant source of HgT to the downstream Seneca River. The hypolimnetic sediments were the dominant source of MeHg to the lake, with demethylation as the dominant fate of MeHg.
Sediment profiles are generally consistent with the historical record of Hg inputs to Onondaga Lake. Sediment Hg deposition was highest during the operation of the chlor-alkali facility. Values have decreased markedly since 1970 and continue to decline today. Concentrations of Hg have remained high in fish tissue despite the reduction in Hg loading to the lake, which indicates that there are other controlling factors.
The investigation of HgT and MeHg in the adjacent wetlands yielded elevated concentrations but no consistent temporal patterns. This observation may require a reevaluation of the plan to create more lake-fed wetlands as fish-breeding habitats.
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