|
Presentation Abstracts
Title: Models Quantify the Ecosystem Approach in the Great Lakes
Author:
Joseph V. DePinto
Senior Scientist, Limno-Tech, Inc.
501 Avis Drive
Ann Arbor, MI 48104
Abstract:The Great Lakes Basin has always been at the forefront of environmental research and management. In the early 1970s, the nationwide Clean Water movement began in the shadow of a burning Cuyahoga River and a declared "dead" Lake Erie. It was Great Lakes scientists who subsequently first raised our awareness of the impacts of toxic, bioaccumulative contaminants (such as PCBs) in aquatic systems and the fact that these substances could be transported long distances in the atmosphere. More recently, the Great Lakes community, suffering ecological havoc from invading aquatic nuisance species, has initiated large-scale research and management programs to address these issues. Mathematical modeling has always been an important part of research and management efforts in the Great Lakes.
Great Lakes researchers have used mathematical models to synthesize knowledge of the processes and overall system behavior of the Great Lakes within particular problem domains. In this way models have in effect served as the repository of our knowledge of large lakes behavior relative to topics like nutrient cycling and eutrophication, toxic chemical transport and fate, and fish production. In doing so, models have helped guide research and data collection to fill in gaps in our understanding of these systems. While the research role for models has been very valuable in itself, the most recognized contribution of models has been their use to guide management decisions within the Great Lakes basin. The Great Lakes modeling community has been a leader in development of sophisticated aquatic system models to aid decision-making on issue related to the appropriate use, protection and restoration of this important resource.
This talk will guide the audience through the history of Great Lakes modeling over the past 50 years, with examples of how modeling has served the research and management community. We will begin with probably the most well known management modeling program in the Great Lakes: the use of nutrient-eutrophication models to establish target phosphorus loadings to each lake that were required to achieve lake-specific phytoplankton biomass criteria (late 1960s – mid 1980s). Following the eutrophication management era, the focus shifted to the assessment and control of toxic substances (mid-1980s – present). Two large, expensive mass balance programs (the Green Bay Mass Balance Study, and the Lake Michigan Mass Balance Study) have proved the feasibility and utility of the development and management application of transport, fate and bioaccumulation models in large lakes. This work spawned other mass balance modeling efforts, including the LOTOX project aimed at supporting the Lake Ontario Lakewide Management Planning process (LaMP). While the state-of-the-science for these models continues to be advanced, the models have already proved valuable for directing our attention to the most important categories of contaminant sources and sinks for the systems of concern.
In the 1990's, scientists began to realize that nutrient and toxic loads were no longer the only important stressors to ecological health in the Great Lakes, but that fishing pressures, loss of habitat and invading species were responsible for significant ecosystem changes within the lakes. This realization spawned a new paradigm of modeling in the Great Lakes. We are now attempting to quantify the "Ecosystem Approach" in the Great Lakes by developing aquatic ecosystem modeling frameworks that account for the effects of multiple stressors acting in concert on multiple ecological endpoints. This new approach to recognizing potential interactions among management issues is exemplified by a recent LTI model that couples interactions among nutrients, phytoplankton and zooplankton growth, zebra mussel impacts, benthic primary production, and PCB cycling and bioaccumulation in Saginaw Bay.
Title: Changes in the Hypolimnetic Oxygen Resources of Onondaga Lake: 1978-2002
Author:
David A. Matthews and Steven W. Effler
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Abstract: Long-term trends in the rate of depletion of hypolimnetic dissolved oxygen (DO) are documented for ionically enriched hypereutrophic Onondaga Lake, NY for the 1978 – 2002 interval. Annual depletion rates, represented as areal hypolimnetic oxygen deficits (AHOD, g·m-2·d-1), are calculated based on weekly DO profiles of one meter resolution and estimates of inputs of DO from overlying layers driven by vertical mixing. Vertical mixing inputs of DO are important in this system, representing from 6 to 45% (mean of 29%) of AHOD. Interannual variations in hypolimnetic temperatures have comparatively minor (± 5%) effects on AHOD. AHOD decreased 53%, from an average of 2.6 g·m-2·d-1 for the 1978–1986 interval to an average of 1.2 g·m-2·d-1 for the 1997–2002 interval. This decrease reflects response to an abrupt decrease in the deposition of particulate organic material into the hypolimnion starting in 1987, associated with a decrease in salinity that resulted from closure of an industry. The time course of the decrease in AHOD is consistent with localization of oxygen demanding processes within the lake's sediments. Implications of the observed decreases in AHOD are discussed with respect to the ongoing lake rehabilitation program.
Title: Changes in Primary Production in Onondaga Lake: Magnitude, Metrics, and Drivers
Author:
Steve W. Effler, Rakesh K. Gelda, Stephen D. Field, Adam J.P. Effler, Erick B. Wallenberg, and David A. Matthews
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Abstract: Changes in phytoplankton primary production and common metrics and drivers of trophic state are documented and critically evaluated for a 35 year (1968 - 2002) period for polluted, culturally eutrophic Onondaga Lake, NY. The lake is presently the focus of an on-going rehabilitation program to abate its cultural eutrophication problems. The analysis is supported by measurements of primary production and long-term monitoring of trophic state metrics and other common limnological parameters. Measurements of gross (Pg) and net primary production and community respiration were made in 1978, 2002, and portions of 2000 and 2001, utilizing dissolved oxygen-based, isolated community (light/dark bottle) and non-isolated community (diel measurements), protocols. Limnological monitoring, conducted annually for most parameters, included: epilimnetic total phosphorus, epilimnetic chlorophyll a (Chle), Secchi disc (SD), and hypolimnetic oxygen deficit (AHOD), salinity (S), downward flux of particulate organic carbon (POCdf), and concentration of TP in the effluent of a wastewater treatment plant (TPMetro) that dominates loading. Direct measurements establish the areal daily average Pg has decreased ~ 30 to 40% since the late 1970s. The magnitude of the decrease closes well with decreases observed in the surrogate metrics of primary production of POCdf (37%) and AHOD (50%). Detailed time series of POCdf and AHOD indicate the decrease occurred abruptly in the late 1980s. This decrease was a result of the reduction in S that attended closure of an industry, rather than a response to the 30-fold reduction in TPMetro achieved over the last 32 years. Onondaga Lake continues to be in a nearly nutrient-saturated state. Magnitudes of Chle and SD are not presently reliable metrics of trophic state in this lake because of increases, and year-to-year variations, in top-down effects. Other features of primary production, beyond magnitude, have changed over the monitored record, including phytoplankton composition, decreases in surface water concentrations of phytoplankton biomass, increases in the depth over which production occurs, and expansion of macrophyte and macroalgae populations.
Title: Modeling Light Attenuation, Secchi Disc and Effects of Tripton in Seneca River, NY
Author:
Rakesh K. Gelda, Steven W. Effler, MaryGail Perkins, and David O'Donnell
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Abstract: The development, testing and application of a probabilistic modeling framework for the light attenuation coefficient for downwelling irradiance (Kd) and Secchi disc transparency (SD), that resolves the effects of several light attenuating constituents, including phytoplankton (represented by chlorophyll concentration, Chl) and non-living particles (tripton), is documented. The model is consistent with optical theory, partitioning the magnitude of light absorption and scattering according to the contributions of the attenuating constituents as simple summations. The probabilistic framework accommodates variations in the character and concentrations of these constituents and ambient conditions during measurements, and recognizes a linear relationship between the magnitudes of absorption and scattering by tripton. The model is tested and applied for a 20 km reach of the Seneca River, NY, that features optical gradients caused by an intervening hypereutrophic lake and dam, and a severe infestation of the exotic zebra mussel. Testing is supported by paired observations of Kd, SD, and direct and surrogate measures of constituent light absorption and scattering at four river sites in 2003. Applications of the model, driven by long-term (12 years) paired measurements of SD and Chl, predicted that decreases in tripton and chlorophyll contributed about 40 and 60%, respectively, to the observed 2.7-fold increase in average SD, and 20 and 80% to the predicted 2.4-fold decrease in Kd, following the zebra mussel invasion. Model analyses demonstrate longitudinal heterogeneity in the contributions of tripton and phytoplankton in regulating observed patterns in SD imparted by natural and anthropogenic drivers along the study reach.
Title: Water Quality Impacts and Indicators of Metabolic Activity of the Zebra Mussel Invasion of the Seneca River
Author:
David A. Matthews, Steven W. Effler, Carol M. Matthews and MaryGail Perkins
Upstate Freshwater Institute Inc.
P.O. Box 506, Syracuse, NY. 13214
Clifford A. Siegfried
New York State Museum
Albany, NY
James M. Hassett
College of Environmental Science and Forestry, SUNY
Syracuse, NY
Abstract: The conspicuous shifts in summertime values of common measures of water qualify that have persisted for ten years (1993 - 2002) in the Seneca River, NY, as a result of the zebra mussel invasion are documented. Resolution of patterns in time and space is supported by water quality monitoring that extends back to the late 1970s. Patterns are evaluated to describe the stability of impacts and quantify metabolic activity of the invader. The water quality impacts, that have persisted unabated for 10 years since the invasion, are the most severe documented for a river in North America. Changes in summer median conditions since the invasion include: (1) a 16-fold decrease in chlorophyll concentration (Chl), (2) a 2.5-fold increase in Secchi disc transparency, (3) a 17-fold increase in soluble reactive phosphorus concentration, (5) a > 25% decrease in dissolved oxygen concentration (DO), and (6) a decrease in pH of 0.55 units. The strength of these signatures has been driven by anthropogenic influences that include upstream nutrient loading and morphometric modifications of the river, and the functioning of Cross Lake, through which the river flows. This hypereutrophic lake sustains dense zebra mussel populations and related water quality impacts in the river downstream of the lake outflow by acting as a source of veligers and suitable food for this bivalve. Evidence is presented that levels of metabolic activity of the zebra mussel in this river have been resource-limited, manifested through increased consumption of Chl and DO with increased delivery of these constituents in the lake's outflow.
Title: Feasibility of a Dual Discharge Diversion Strategy for the METRO Effluent
Author:
Martin T. Auer, Daniel K. Rucinski, David W. Watkins
Department of Civil & Environmental Engineering, Michigan Technological University
Houghton, MI 49931
Abstract: Excessive phosphorus (P) loading has played a major role in the degradation of water quality conditions in Onondaga Lake. Efforts to reduce P loading to the lake have focused on P removal at the Metropolitan Syracuse Wastewater Treatment Plant (Metro), the lake's major P source. Model simulationsindicate that lake water quality goals cannot be met unless heroic levels of P removal are achieved at Metro. An alternative plan has been proposed which combines more modest levels of P removal with diversion of the Metro effluent to the Seneca River.
Under this dual discharge strategy, the Metro effluent would be directed to the river except when the system's assimilative capacity is challenged. Under those conditions, the effluent would be directed to the lake and maintained there until circumstances in the river improved. The key to the viability of the dual discharge strategy lies in the frequency and magnitude of challenges to the assimilative capacity ofthe river. Here, we use a 30-year historical data base to simulate river assimilative capacity and its impact on the feasibility of the dual discharge approach. This probabilistic analysis defines the magnitude and frequency of departures from water quality goals for the lake (phosphorus) and the river (oxygen) expected under the dual discharge scenario. Model simulations demonstrate that water quality goals for both the lake and river can be achieved under the dual discharge strategy. This plan may offer advantages with respect to technological feasibility, long-term economics and public acceptance of lake restoration efforts
Title: The Onondaga Lake Remedial Investigation, Documentation of an In-Lake Waste Deposit
Author:
Robert Montione, Edward Garvey, Michael L. Spera, Kelly Robinson
TAMS/Earth Tech (under contract with NYSDEC)
New York, NY
Solomon Gbondo- Tugbawa
Currently with Malcolm Pirnie, Inc.; work performed as employee of TAMS/EarthTech
Colby Snyder
YEC, Inc. under contract with TAMS/EarthTech
Abstract: This presentation will summarize one important aspect of the recently completed Remedial Investigation (RI) report for Onondaga Lake. The historical disposal of industrial wastes into the southern corner of Onondaga Lake was documented as part of the RI using data from water and sediment sampling, as well as historical accounts and aerial photographs. The materials that form the lake bottom in a portion of the southwestern corner of Onondaga Lake consist almost entirely of Honeywell wastes. The location of this deposit of wastes is adjacent to the shore in the area of the causeway at Honeywell's Willis Avenue site and extends east of the mouth of Harbor Brook for a distance of about one mile. These wastes are believed to have been disposed of by discharging a combination of cooling water, sanitary waste, Solvay waste, mercury wastes, and organic chemical wastes into the lake (via the East Flume), where they settled out, forming a large delta.
This in-lake waste deposit is estimated to be over 10 m thick, with a maximum reported thickness of 14.6 m, representing about 2.6 million cubic meters of material. This material represents some of the most contaminated "sediment" contained within the lake. Elevated concentrations in the surface sediment, porewater, water column, and biota in this area provide evidence of ongoing re-release of contamination, suggesting that contaminants contained in the in-lake waste deposit are not sequestered from the lake. Its location in the littoral zone is considered to be relatively unstable, with the material subject to wind-driven resuspension and bioturbation, among other re-release processes.
Title: Hydrogeology of the Onondaga Valley Aquifer -- The Good, the Bad, and the Brine
Author:
William Kappel
US Geological Survey
30 Brown Road
Ithaca, NY 14850-1573
Abstract: The natural brine-filled aquifer that gave Syracuse the nickname "The Salt City" could possibly confound the clean-up of Onondaga Lake unless the characteristics of this aquifer system are understood. The U.S. Geological Survey is presently studying the Onondaga Valley aquifer in conjunction with the Onondaga Lake Partnership (a consortium of local, state, and federal agencies) to identify the source of brine and define its movement and concentration within the aquifer. The aquifer lies within the Onondaga Creek valley and extends from Tully north to Onondaga Lake and beyond. The results of the 4-year study should provide the data needed to discern whether the brine from the aquifer discharges into the lake and whether it might affect the cleanup of the lake and its bottom sediments.
Initial drilling plans and water-quality assessments were based on data collected previously throughout the Onondaga Creek basin. Five deep boreholes (~400 feet deep) were drilled during the summer of 2002. Water-quality and drillhole data indicate that the aquifer system in the Tully valley has a limited hydraulic connection to the Onondaga Valley aquifer system further north. Data from deep boreholes drilled several miles north of U.S. Route 20 indicate that concentrations of sodium chloride in the unconsolidated aquifer increase northward from south of Syracuse to the outlet of Onondaga Lake and range from 3 to more than 5 times as salty as seawater. This concentration gradient indicates that the brine is probably derived not only from beds of halite in the Syracuse Shale, which is exposed along the bedrock floor of the valley north of U.S. Route 20, but also from fractures in the surrounding bedrock through which brine is discharged to the unconsolidated aquifer within the valley.
The sediments and quality of water in unconsolidated aquifers in some of the surrounding tributary valleys, and below the floor of Onondaga Lake were characterized from drillhole data collected during the summer of 2003. The tributary valleys in which drillholes were installed include the Ninemile Creek valley, the Seneca River valley upstream and downstream of Onondaga Lake, and the West Branch valley of Onondaga Creek. Data from these drillholes indicated that the brine is most highly concentrated in the main valley but also occurs in some tributary valleys adjacent to the main valley. The drillholes in Onondaga Lake were several hundred feet from the northern and southern shores; one was in the middle of the lake. Data from these drillholes indicate a thick sequence of fine-grained sediments below the lake floor. Presumably, brine under artesian pressure slowly diffuses through these sediments and discharges upward into the lake through the lake-bottom sediments.
The brine is rich in sodium chloride and is probably derived from the dissolution of halite (rock salt); it could not originate in deep bedrock because it does not have high concentrations of heavy metals usually associated with deep basin brines found in natural gas fieldsfurther south and west of Syracuse. This conclusion is supported by isotopic data, which indicate the brine to be fairly young in age (20,000 years or less) and, therefore, of glacial and postglacial origin.
Hydrogeologic and water-quality data are still being collected and will be used to construct a regional ground-water-flow model of the unconsolidated aquifer system. Model results could help limnologists, hydrologists, and decisionmakers to (1) develop a regional concept of the brine-bearing aquifer, including the effect of brine on the fresh ground-water flow system, the cleanup of hazardous-waste sites close to the lake, and the possible remediation of lake-bottom sediments, and (2) indicate the degree to which the brine affects the lakes water quality.
|
