MaryGail Perkins

Chloride model for polluted onondaga lake

Abstract The validation of a mass balance chloride (Cl) model for enriched Onondaga Lake is documented for the period 1973–1991. The history of loading of Cl to the lake, extending from the mining of NaCl brines adjoining the lake in the late 1700s, through the 102 year period of operation and discharges of an adjoining soda ash/chlor-alkali facility, is reviewed. Loads are estimated for the 1973–1991 interval based on a program of continuous flow measurements and bi-weekly monitoring of Cl concentration for the major inflows. The model performs well in matching the substantial seasonal variations in lake Cl concentration and the major reduction in concentration observed since closure of the facility in 1986 (from about 1585 to 430 mg l −1 ). Projections with the validated model demonstrate the Cl concentration in the lake would be about 230 mg l −1 , nearly 50% lower than the present concentration, without the continuing waste input from the soda ash/chlor-alkali facility.

Tripton, transparency and light penetration in seven New York reservoirs ∗

Temporal patterns and inter-system differences in the attenuation coefficient for scalar irradiance (Ks), Secchi disc transparency (SD), several measures of tripton, and chlorophyll a (Chl) are documented for the lacustrine zones of seven reservoirs (nine distinct basins) in New York (U.S.A.), based on a single year of comprehensive measurements. Analyses of these data and historic (12 years) observations of SD and Chl, including application of empirical and deterministic modeling frameworks, demonstrate that inorganic tripton is the primary attenuating constituent responsible for the substantial differences in Ks and SD among these basins, and the major temporal variations observed in these optical characteristics in most of the study basins. These inorganic particles, of terrigenous origins, are supplied directly to the water column of these basins in inflows, particularly during runoff events, and through the sediment resuspension process. Comparison of the measures of tripton indicates electron-microscopy-based measurements performed somewhat better than gravimetric analyses in explaining the variations in Ks and SD in the lower concentration systems. Increases in average SD values by factors of 2–5, compared to prevailing values, are predicted for the study basins with the deterministic model for the case of no tripton.

The Optical Water Quality of Cannonsville Reservoir: Spatial and Temporal Patterns, and the Relative Roles of Phytoplankton and Inorganic Tripton

ABSTRACT Longitudinal and temporal distributions of optical properties, and the relative role of selected light attenuating constituents in regulating light penetration, in Cannonsville Reservoir, NY, in 1995 are documented. The analysis is supported by field measurements of light penetration; die angular distribution of irradiance (reflectance); and the spectral quality of penetrating light; laboratory measurements of turbidity, chlorophyll, gelbstoff, and microscopy-based individual particle size and elemental chemistry, and calculations of absorption and scattering coefficients and their components. Longitudinal gradients in attenuating components, and therefore optical properties, prevailed along the main axis of the reservoir; light attenuation and the relative role of scattering decreased with the approach to the dam. Large temporal variations in optical characteristics occurred. These dynamics were mostly controlled by variations in phytoplankton biomass in spring and early summer, when the reservo...

Optical Characteristics of Onondaga Lake: 1968–1990

ABSTRACT We analyzed measurements of light penetration, the angular distribution of irradiance, the spectral quality of light attenuation, chlorophyll, gelbstoff, and turbidity to depict seasonal dynamics and long-term trends in these optical characteristics for eutrophic Onondaga Lake, NY, over the 1968–1990 period. Strong seasonality in optical characteristics has been common in the lake, particularly since the closure of an adjoining soda ash/chlor-alkali manufacturing facility, associated with the dynamics of phytoplankton biomass, inputs of terrigenous particles, and probably zooplankton grazing. The New York State requirement for Secchi disc depth (SD) (1.2 m) was only met for about 20% of the observations before the closure of the soda ash/chlor-alkali facility in 1986. Since closure, there has been a shift to increased light penetration as a result of reductions in the concentrations of attenuating particles. About 65% of SD observations since the closure have met the SD standard. Blue color is no...

Patterns and modeling of the long-term optics record of Onondaga Lake, New York

A retrospective analysis of long-term data sets of Secchi disc depth (SD, 40 years), the diffuse light attenuation coefficient for downwelling irradiance for photosynthetically available radiation (k d (PAR), 23 years), and chlorophyll-a ([Chl], 28 years), is presented for culturally eutrophic and industrially polluted Onondaga Lake, New York. The effects of changes in multiple drivers on SD and k d (PAR) are resolved in the record, including: (1) salinity decreases from closure of an industry, (2) changes in the grazing by exotic and native Daphnia, (3) long-term variations in populations of planktivorous fish, (4) runoff events, and (5) progressive decreases in phosphorus (P) loading. Four time intervals, or regimes, are identified for the record that had unifying features with respect to drivers and SD observations. The most dramatic changes in clarity conditions were the abrupt transition to annual occurrences of a clear-water phase (CWP) for 16 years following a coupled decrease in salinity and return of native Daphnia, and the subsequent loss of the CWP (for 5 years) from the loss of these cladocerans. The CWP was characterized by coincident dramatic increases in SD (annual maxima ≥ 4.55 m) and decreases in [Chl] and high densities of Daphnia. The benefits of P management were most clearly manifested by a 3-fold decrease in average [Chl] and a 2-fold increase in SD between two of the regimes, separated by 25 years, which both lacked CWPs. A probabilistic mechanistic model for SD and k d (PAR), that represents the effects of multiple constituents on the regulating processes of absorption and scattering, is developed, tested for the long-term record. The model is applied to partition the scattering coefficient (b) according to contributions of phytoplankton and tripton (b NAP ). Good model performance is demonstrated through: (1) closure of estimates of b with independent measurements, (2) consistencies of b NAP predictions with independent estimates based on an individual particle analysis technique, and the timing of runoff events, and (3) closure of predictions of k d (PAR) with observations. Broadly applicable nomographs are formed with the model that represent the dependence of SD and k d (PAR) on phytoplankton ([Chl]) and inorganic tripton (b NAP ) levels, that can be used to predict responses of these optical metrics to changes in the levels of these attenuating constituents. Inorganic tripton in the size range 1 to 10 μm, has played a critical role in influencing important features of the lakes optical regime by: (1) contributing importantly to b throughout the record (30 to 40 %, on average), (2) regulating optical signatures from runoff and CWP events, and (3) limiting increases in SD that can be achieved from decreases in phytoplankton biomass.

Light absorbing components in the Finger Lakes of New York

Light absorbing constituents are important regulators of the underwater light field and the signal available for remote sensing of water quality. The spectral characteristics, magnitude and variability of the components of light absorption are documented and contrasted here for the broad range of conditions manifested in the 11 Finger Lakes of New York. The absorption coefficient, a (m -1 ), was partitioned according to the additive components of colored dissolved organic matter (a CDOM ), non-algal particles (a NAP ), phytoplankton (a Φ ), and water itself (a w ; known), using laboratory spectrophotometric protocols on near surface samples collected monthly in 2004. Bulk in-situ measurements included Secchi disc depth (SD), irradiance profiles to determine the diffuse attenuation coefficient (K d , m -1 ), and the beam attenuation coefficient at 660 nm [c(660)]. The average exponential slope values for CDOM (0.0175nm -1 ) and NAP (0.0121nm -1 ) were nearly equivalent to, and spectral features of aΦ were similar to, those reported by Babin et al. (2003b) for coastal marine waters around Europe. Order of magnitude differences in study average values of a CDOM , a NAP , and a Φ were observed amongst the study lakes. The largest component in each of the lakes, for the commonly adopted reference wavelength of 440 nm, was CDOM; it represented from 48 to 68 % of a amongst the study lakes. The a NAP and a Φ components were approximately of equal importance, with a NAP (440) exceeding a Φ (440) in 6 of the lakes. The value of a, from summation of the measured components, was a strong predictor of K d differences amongst the lakes, and it had significant relationships with average values of SD and c(660). The ratio of the watershed area to the lake volume was found to be a strong predictor of the major differences in both a CDOM (440) and a NAP (440) amongst the lakes indicating the importance of terrigenous inputs of these constituent.

Ionic Inputs To Onondaga Lake: Origins, Character, and Changes

ABSTRACT The origins and loadings of Cl−, Na+, and Ca2+ to ionically polluted Onondaga Lake, NY, are determined based on monitoring data collected for surface inflows over the 1973–1993 interval. The analysis delineates for lake managers the central role a chemical company has played in the loading of these constituents to the lake and the resulting ionic enrichment of the lake. The recurring, but disparate, ratios of Cl−, Na+, and Ca2+ concentrations maintained in the two largest tributaries to the lake depict contrasting industrial and geologic origins of these constituents. Concentrations of the three ionic species are inversely related to flow in these tributaries. The average annual combined loading of Cl−, Na+, and Ca2+ to the lake over the last 12y of operation of the chemical plant was 1.2 million metric tons. The plant closed in 1986, and by 1989 the annual loads of Cl−, Na+, and Ca2+ had decreased by about 79, 67, and 70% respectively. The residual annual input of the ionic waste in 1989, from t...

Optics of Little Sodus Bay

Abstract Optical properties of Little Sodus Bay are described for the summer to fall interval of 1988 and contrasted to those at an adjoining Lake Ontario station. Light penetration, the angular distribution of irradiance, and the spectral Quality of underwater irradiance were quantified by measurements with a Secchi disk, quantum sensors, and a spectroradiometer. A partitioning of light absorbing and light scattering components is presented. Light attenuation was much higher in the bay than in the lake because of the elevated levels of light absorption and scattering that prevailed in the bay, associated with the higher concentrations of phytoplankton, gelbstoff, and perhaps tripton. The enrichment with these materials also caused disparate spectral attenuation characteristics between the bay and the lake that were manifested as strong differences in appearance. Calcium carbonate particles were an important component of light scattering in both systems in the early part of the study. This material had a particularly striking effect on the angular distribution of irradiance in the lake.

Turbidity and Particle Signatures Imparted by Runoff Events in Ashokan Reservoir, NY

ABSTRACT The occurrence, temporal and spatial patterns, and origins of turbidity events, and their linkage to runoff events, are documented for a water supply impoundment with two separated basins, Ashokan Reservoir, NY. The analysis is supported by a comprehensive 6-week study of the major inflow and the reservoir during the summer of 1996, that captured the effects of a single runoff event, and turbidity (Tn) measurements made in the reservoir and the water supply intakes for the entire year. Measurements supporting the short-term study include: temperature, specific conductance, beam attenuation coefficient, electronic particle counts, Secchi disc transparency, Tn, up- and downwelling cosine irradiance, chlorophyll, microscopy-based individual particle size and chemistry, and total suspended solids (TSS) on sediment trap collections. The external load of mostly quartz and clay particles delivered by die principal tributary, as an interflow, during the summer runoff event imparted distinct signatures in...

An Optics Model for Onondaga Lake

ABSTRACT 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 Kd in the lake are phytoplankton and tripton (...