摘要:

A deterministic optics model for predicting measures of light penetration, including Secchi disc transparency (or clarity; SD) and the vertical attenuation coefficient for downward irradiance (Kd), from concentrations of various attenuating substances, is developed, calibrated, and applied for culturally eutrophic Onondaga Lake, NY. The model is an invaluable management tool for establishing the appropriate focus and realistic expectations for improving clarity in the lake. The model is consistent with optical theory, partitioning attenuation according to the processes of absorption and scattering, and materials contributing to these processes. The model is developed from optical measurements made for the lake over the 1987–1990 interval, reported by Perkins and Effler (1996), and attendant estimates of the values of absorption and scattering coefficients presented herein. It is demonstrated that the primary components responsible for low SD and high Kdin the lake are phytoplankton and tripton (other than CaCO3particles). Gelbstoff and CaCO3particles are relatively unimportant. Management efforts to improve clarity should focus on the lake's cultural eutrophication problem. Terrigenous particle inputs received during runoff events would continue to substantially reduce clarity for brief periods if they are not abated.

ISSN:1040-2381    

DOI:10.1080/07438149609354002

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The recent history of loading of total phosphorus (TP) and nitrogen (N) species to Onondaga Lake, NY, from an adjoining domestic waste treatment facility (METRO), and related impacts on die lake, are documented. The discharge from METRO represents an extraordinary contribution to the inflow of the lake; e.g., in most years it is the largest source of water during the month of August. Approximately a 20-fold reduction in effluent TP concentration has been achieved by METRO over die 1970–1993 period, in response to a detergent ban and increased levels of treatment. The TP loading from the facility decreased about 5-fold over the 1977–1992 interval. A significant level of nitrification has been achieved during die warmer mondis since the late 1980s, but this has been attended by increased effluent concentrations of nitrite (NO−2). METRO presently contributes approximately 60, 90, and 80% of the total external loads of TP, ammonia, and total N, respectively. The extremely high prevailing external total loads of TP and total N, approximately 8 and 200 g/m2/y, respectively, severely impact die lake. Recurring degradations associated with the cultural eutrophication of the lake include excessive concentrations of phytoplankton, poor clarity, rapid loss of oxygen from die hypolimnion, and lake-wide oxygen depletion during die fall mixing period. Related water quality standards for transparency and oxygen are violated. A state guidance value for summer epilimnetic TP concentration of 20 μg/L is exceeded by a factor of ≥ 3 annually. Standards to protect aquatic life against the toxic effects of free ammonia and NO−2are violated by a large margin routinely in die upper waters in summer. METRO is die appropriate focus for related remediation efforts.

ISSN:1040-2381    

DOI:10.1080/07438149609354003

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Adynamic two-layer mass balance model for total phosphorus (TP) is developed for culturally eutrophic Onondaga Lake, NY, and tested for the May 1987 through 1990 period. The model accommodates key processes in the lake's phosphorus cycle, including settling of the particulate fraction of TP, sediment release, and vertical mass transport Model development and testing were supported by a comprehensive program of field and laboratory measurements and experiments, to determine model coefficients and external loads, and to establish temporal and vertical distributions of lake TP concentrations. The model performs well in tracking documented interannual, seasonal, and vertical distributions of TP in the lake, and thus is appropriate as a management tool to evaluate management scenarios aimed at abating the lake's cultural eutrophication problem.

ISSN:1040-2381    

DOI:10.1080/07438149609354004

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A dynamic two-layer mass balance model for total nitrogen (N) and various species of N is developed and tested for Onondaga Lake, NY, a system in which high concentrations of total ammonia (T-NH3) prevail. The model simulates concentrations of T-NH3, nitrate plus nitrite, particulate organic N (PON), dissolved organic N, total Kjeldahl N, and total N. Processes of the N cycle accommodated include net phytoplankton growth, nitrification, denitrification, ammonification, decay of PON, volatilization of free ammonia, sediment release of T-NH3, settling of PON, and vertical mixing-based exchange between the layers. Model testing is supported by a comprehensive monitoring database of lake concentrations of the N species, and tributary and waste discharge concentrations for calculation of loads. Model credibility is enhanced by the independent determination of several important model coefficients based on field and laboratory experiments, which greatly reduces the role of calibration. Model verification is established by the successful simulation of the distinctly different distributions of various N species documented for the lake in 1989 and 1990. The model is particularly successful in simulating T-NH3concentrations in the upper waters, and is thus appropriate to evaluate various related remediation strategies for the lake.

ISSN:1040-2381    

DOI:10.1080/07438149609354005

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A mechanistic, two-layer mass balance model for dissolved oxygen (DO) in Onondaga Lake, a hypereutrophic, urban system, has been developed and tested. The model accommodates the processes of reaeration, algal photosynthesis and respiration, carbonaceous biochemical oxygen demand (CBOD), nitrogenous biochemical oxygen demand (NBOD), sediment oxygen demand (SOD) and water column oxidation of reduced species. Most model inputs, and many of the kinetic coefficients, were developed through a program of field monitoring and field and laboratory experimentation. The model was calibrated and verified using data collected in 1989 and 1990, respectively. Severe dissolved oxygen depletion is observed in the hypolimnion (lower mixed layer; LML) of Onondaga Lake during summer stratification. SOD and water column oxidation of reduced species diffusing from the sediment are together responsible for >70% of the summer depletion; CBOD, NBOD and algal respiration account for the balance. DO depletion occurs in the epilimnion (upper mixed layer; UML) in the fall. Oxidation of reduced species entrained from the LML is responsible for about 30% of the fall depletion, with algal respiration and mass transport to the LML accounting for about 25% each; CBOD and NBOD are minor sinks. Beyond those features of pollutant loading, fate, and transport, sensitivity analyses suggest mat meteorological conditions importantly influence the character of the DO resources of the lake.

ISSN:1040-2381    

DOI:10.1080/07438149609354006

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Management models for total phosphorus (TP), various nitrogen (N) species, and dissolved oxygen (DO), for polluted culturally eutrophic Onondaga Lake are developed from models presented and tested earlier in this issue (Doerr et al. 1996a, Canale et al. 1996, Gelda and Auer 1996). The management models are applied to test a wide range of remediation alternatives, corresponding to a wide range of reductions in pollutant loading. The analysis focuses primarily on the effluent (3.5 m3/s(80 MGD)) received from an adjoining domestic wastewater plant (METRO), though a reasonable upper bound of reductions in tributary TP load also is considered. The decreases in lake TP and total ammonia (T-NH3) concentrations that could be achieved by partial diversion of METRO, increased treatment at METRO, and reductions in tributary loading, would not be adequate to meet the established in-lake TP goal of 20 μg/L (as a summer average in the upper waters), the T-NH3standard for the lake (0.77 mgN/L for the upper waters in summer), nor the DO standard for the lake's upper waters (daily average ≥5 mg/L). Diversion of the entire METRO discharge around the lake is found to be necessary to meet the T-NH3standard, to approach or meet the TP concentration goal, and to avoid violation of the DO standard in the upper waters during fall. Reductions in the prevailing tributary TP load, of as much as 30%, may be necessary to reach the TP goal.

ISSN:1040-2381    

DOI:10.1080/07438149609354007

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A one-dimensional hydrothermal model is used to forecast the impact of a proposed hypolimnetic discharge of treated municipal wastewater on stratification and mixing in Onondaga Lake, NY. Important simulated impacts are increased temperatures in the hypolimnion, reductions in density stratification, increased mixing and homogeneity within the hypolimnion, and reductions in the duration of summer stratification. Predictions from this analysis serve as input to water quality models that simulate related impacts of this management action. Features of the hydrothermal model include simulation of entrainment associated with plunging inflows, capability for simulations during ice cover, and a submodel to simulate the near-field mixing associated with a multiport diffuser. The model successfully simulated six consecutive years of historical stratification conditions. The model performs well in simulating the dimensions and temperatures of layers, and the timing/duration of stratification. The model is less successful in simulating the more subtle effects of dense saline inflows that linger from a recently closed soda ash/chlor-alkali facility, such as intermittent formation of chemical stratification during spring and fall mixing.

ISSN:1040-2381    

DOI:10.1080/07438149609354008

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Water quality impacts of shifting the shoreline discharge of a major (3.5m3/s) domestic wastewater treatment faclity (METRO) on polluted, eutrophic Onondaga Lake, NY, to a deep-water location are evaluated with three mechanistic water quality models. Transport and mixing inputs for the simulations are specified from the output of a separate hydrothermal model (Owens and Effler 1996). Model simulations indicate, that by trapping enriched effluent in the lower layers, summertime concentrations of total phosphorus (TP) and total ammonia (T-NH3) would decrease in the upper mixed layer (0 to 4.5 m depth interval). Further reductions in the concentrations of those constituents would be realized by reducing sediment release, through maintenance of oxia in the hypolimnion. However, the decreases that could be achieved with the prevailing METRO effluent characteristics would not result in substantial reductions in phytoplankton growth nor prevent violation of the T-NH3standard. An extremely high degree of nitrification would be needed at METRO, particularly during the late fall to early spring interval (e.g., T-NH3, concentrations < 3.6 mgN/L in effluent), to avoid violation of the T-NH3standard. Oxygen concentrations in the existing METRO effluent would have to be maintained at approximately 70 mg/L to ensure the hypolimnion remains oxic. To provide oxygen concentrations ≥5 mg/L in the hypolimnion, oxygen concentrations of = 130 mg/L would have to be maintained in METRO's effluent.

ISSN:1040-2381    

DOI:10.1080/07438149609354009

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor