GLERL Publications Abstracts: FY 1984

ASSEL, R.A. Lake Erie regional ice cover analysis: Preliminary results. NOAA Technical Memorandum ERL GLERL-48, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB84-138734) 33 pp. (1983).

A 20-year (1960-79) digital ice concentration data set for Lake Erie was divided into nine half-month periods, staring the last half of December and ending the last half of April. Observation density, average regional ice cover, and percentage ice cover exceedance were calculated for the three regions of the lake: region 1--the entire lake; region 2--the lake east of Long Point, Ont.; and region 3--the lake east of Port Colborne, Ont. Results of the analysis are presented in tables and graphs of percentage of region observed, average ice cover, and percentage exceedance from average ice cover. Seasonal and regional trends in ice cover extent are discussed.

ASSEL, R.A. Sub-committee report: Summary of the discussion on ice information and forecasting. Proceedings, Great Lakes Ice Research Workshop, R.A. Assel and J.G. Lyon (eds.), Ohio State University, Columbus, OH, October 18-19, 1983. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 65-71 (1984).

No abstract.

*ASSEL, R.A., and J.G. Lyon. Proceedings, Great Lakes Ice Research Workshop, R.A. Assel and J.G. Lyon (eds.), Ohio State University, Columbus, OH, October 18-19, 1983. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 76 (1984).

No abstract.

ASSEL, R.A., F.H. QUINN, G.A. LESHKEVICH, and S.J. BOLSENGA. NOAA Great Lakes Ice Atlas. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 115 pp. (1983).

Over 2,800 historic Great Lakes ice charts spanning 20 winters (1960-79) were digitized and converted to discrete 5-by-5-km grid cells. This data set was analyzed to produce a series of 46 plates, including 9 for each of the 5 Great Lakes with one extra plate for Lake Michigan. The plates portray charts of maximum, minimum, and normal ice concentration patterns and observation density for nine semimonthly periods beginning the last half of December and ending the last half of April. The percent of the surface area covered by ice was calculated for each ice chart and summarized in tabular format. In addition, a 10-year data set of ice thickness in the nearshore zone of the Great Lakes, i.e., primarily in bays and harbors, is presented to identify ice thickness ranges and ice statigraphic patterns for the Great Lakes Region. To complete this Atlas, air temperatures at 25 stations on the perimeter of the Great Lakes for an 80-winter period (1898-1977) were used to classify winter severity classes, based on freezing degree-days. Winter severity trends for the pre- and post-ice concentration climatology periods are identified on annual and semimonthly time scale for individual stations and for lakewide averages.

AUBERT, E.J. Advisory mechanisms supporting the mission of the IJC. In Review of the Great Lakes Water Quality Agreement--Working papers and Discussion, The Water Science and Technology Board, National Research Council, National Academy Press, Washington, DC, 68-86 (1984).

No abstract.

AUBERT, E.J. Capabilities of various research organizations to provide information on Great Lakes water quality. NOAA Technical Memorandum ERL GLERL-52, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB85-106623/XAB) 23 pp. (1984).

This report presents information on the nature of Great Lakes water quality problems that should be addressed over the next decade by research organizations that support the Great Lakes water quality mission of the International Joint Commission. This information is relevant to the research programs and capabilities required by such research organizations in the United States and Canada. This analysis, based upon the perception of issues and ecosystem understanding of the author, covers the following topics: a) the nature of the Great Lakes water quality problem, b) a conceptual model of an environmental quality management system, c) the eutrophication problem, and d) the toxic organics problem. Future water quality management decisions will be more complex owing to conflicts of use, and more in-depth assessments will be required for implementation. This report is intended to put into perspective the Great Lakes Water Quality problems and to pose key questions relative to environmental research capabilities required over the next decade.

BELL, G.L., and B.J. EADIE. Variations in the distribution of suspended particles during an upwelling event in Lake Michigan in 1980. Journal of Great Lakes Research 9(4):559-567 (1983).

To test the hypothesis that suspended fine-grained particles moving downslope within the nepheloid layer in Lake Michigan are periodically reintroduced into the nearshore and euphotic zones during, upwelling events, temperature and transparency profiles were recorded and water samples analyzed for total suspended materials (TSM) during a strong upwelling event. The resultant data confirmed that there is periodic reintroduction of suspended materials into the nearshore and epilimnion during such events, and provided insight into the importance of the general resuspension process, especially in regard to differences between known sedimentation rates and the rate indicated by trap collections. Both upwelling and downwelling currents are disruptive processes that tend to keep the suspended particulates in motion and prevent them from rapidly becoming a permanent part of the bottom sediment. These currents redistribute suspended particulates and the associated chemical load, and may resuspend surficial sediments, especially from the slope and shelf regions. The reintroduction of fine-grained materials into the euphotic zone through upwelling events can play a large role in the long-term behavior and fate of persistent contaminants.

BOLSENGA, S.J. Spectral reflectances of snow and freshwater ice from 340 through 1100 nm. Journal of Glaciology 29(102):296-305 (1983).

Measured spectral reflectances of new and moderately metamorphosed snow were generally >80% from 340-950 nm. From 950-1100 nm a characteristic dip and rise of spectral reflectances occurred. One spectroradiometer scan over a deteriorated snow patch showed much lower spectral reflectances than fresh snow, but the shape of the curve remained similar to that of fresher snow. Spectral reflectances for clear ice contrasted sharply with those for snow. In general, values were <10% and the curves lacked distinctive shape. Higher spectral reflectances, due to "lighter"-appearing ice in the measurement area, were measured at some sites. Refrozen slush, pancake, brash, and slush curd ice revealed spectral reflectance curves similar in form to each other, but which varied significantly in the range of spectral reflectances for each ice type. Generally, reflectances rose slowly from 340 nm to a peak near 550 nm. From 550-775 nm reflectances decreased slowly but significantly. A slight dip and rise in reflectances occurred from 775-850 nm after which values again dipped significantly (850-900 nm). From 950-1100 nm, a dip and rise in reflectances similar to that for snow was observed. The amount of slush included seems to control the reflectances of these ice types. All measurements were acquired with a pair of scanning spectroradiometers having picowatt accuracy, adapted to obtain, automatically, simultaneous readings of incident and reflected radiation from 340-1100 nm. The spectroradiometers were field-calibrated using sun-plus-sky radiation as a calibration source.

**CHAPRA, S.C., and K.H. Reckhow. Engineering Approaches for Lake Management, Vol. 2: Mechanistic Modeling. Butterworth Publishers, Boston, MA, 419 pp. (1983).

No abstract.

CHAPRA, S.C., D. SCAVIA, G.A. LANG, and K.H. Reckhow. Nutrient food chain models. In Engineering Approaches for Lake Management, Vol. 2: Mechanistic Modeling, S.C. Chapra and K.H. Reckhow (eds.). Butterworth Publishers, Boston, MA, 243-351 (1983).

No abstract.

CROLEY, T.E.II. Lake Ontario Basin (U.S.A.-Canada) runoff modeling. Journal of Hydrology 66:101-121 (1983).

An interdependent tank-cascade model of basin runoff is described; it employs analytical solutions of climatological considerations relevant for large watersheds. The mass balance is coupled with physically-based concepts of linear reservoir storages, partial-area infiltration, complementary evapotranspiration and evapotranspiration opportunity based on available supply and heat-balance determinations of snowmelt and net supply. Daily air temperature, precipitation and runoff data are required for calibration of the nine parameters; data are grouped for 15 watersheds about Lake Ontario as well as for the entire basin above Elevator, New York and Kingston, Ontario. The model is applied to the Lake Ontario Basin in both lumped- and distributed-parameter approaches; eleven subbasins and two basins are modeled for 7- and 30-day mass-balance computation intervals. Parameter values are interpreted for physical meaning and relation to data errors and computation intervals. Temporal and spatial integration effects are analyzed with respect to error reduction, modeling information and resolution, and cost trade-offs. Result summaries are given depicting model applications and validity. Extensions and improvements are discussed. The model is an accurate, fast representation of weekly or monthly runoff volumes from large watersheds with simple calibration and data requirements. Parameter values have physical significance and appear reasonable and consistent.

CROLEY, T.E., II, and G.R. Foster. Unsteady sedimentation in nonuniform rills. Journal of Hydrology 70:101-122 (1984).

Runoff and sediment were measured from agricultural land exposed to controlled simulated rainfall. We extended the kinematic unsteady overland sedimentation theory of prismatic channels to the experiments by considering both hydraulics and sediment dynamics of rill flow for changing flow geometries of nonuniform and unsteady rill development. The characteristic unimodal concentration peak observed in the experiments and the changing channel geometry were interpreted in theoretical terms. Overland sedimentation in unsteady nonprismatic rills under uniform rainfall can be described with kinematic models of flow, entrainment and deposition applied to developing flow geometries; this is not possible with sheet-flow models. Other interpretations are considered and experimental needs are identified.

CROLEY, T.E., II, and H.C. HARTMANN. Lake Superior Basin runoff modeling. NOAA Technical Memorandum ERL GLERL-50, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB84-230028) 295 pp. (1984).

The GLERL Large Basin Runoff Model is applied to the Lake Superior Basin; it is an interdependent tank-cascade model, which employs analytical solutions of climatological considerations relevant for large watersheds. The mass balance is coupled with physically-based concepts of linear reservoir storages, partial-area infiltration, complementary evapotranspiration and evapotranspiration opportunity based on available supply, and degree-day determinations of snowmelt and net supply. Daily or monthly air temperature, precipitation, and runoff data are required for calibration of the nine parameters; data are grouped for 22 watersheds about Lake Superior, as well as for the entire basin above Sault Ste. Marie, Mich. The model is applied to the Lake Superior Basin in both lumped- and distributed-parameter approaches. Twenty subbasins and the entire basin are modeled for 1-d, 7-d, and monthly mass-balance computation intervals. The 1-d and 7-d models use daily data and compute net supply and evapotranspiration opportunity on a daily basis. The monthly model uses monthly data and computes net supply and evapotranspiration opportunity on a monthly basis. Parameter and soil moisture values are interpreted for physical meaning; soil moisture is also related to basin characteristics. Result summaries depicting model applications and validity are given. The model is extended to forecast net basin supplies to Lake Superior. There are examinations of sensitivity of the forecasts to initial conditions and discussions of improvements in forecasting. The model is an accurate, fast representation of weekly or monthly runoff volumes from large watersheds, and it has simple calibration and data requirements. Parameter values have physical relevance and appear reasonable. The model has good potential, when using near real-time data, for semiautomatic generation of practical probabilistic outlooks of runoff and net basin supply.

DERECKI, J.A. Detroit River physical and hydraulic characteristics. GLERL Open File Report, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (1984).

No abstract.

DERECKI, J.A. St. Clair River physical and hydraulic characteristics. GLERL Open File Report, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 10 pp. (1984).

No abstract.

DERECKI, J.A. St. Marys River physical and hydraulic characteristics. GLERL Open File Report, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (1984).

No abstract.

EADIE, B.J. Distribution of polycyclic aromatic hydrocarbons in the Great Lakes, Chapter 9. In Toxic contaminants in the Great Lakes, Vol. 14, J.O. Nriagu and M.S. Simmons (eds.). John Wiley and Sons, New York, 195-211 (1984).

No abstract.

FAHNENSTIEL, G.L., D. SCAVIA, and C.L. Schelske. Nutrient-light interactions in the Lake Michigan subsurface chlorophyll layer. Verhandlugen-Internationale Vereinigung Fur Theoretische und Angewandte Limnologie 22:440-444 (1984).

Nutrient regulation of phytoplankton growth and species composition in Lake Michigan has received much attention (see Tilman et al. 1982; Schelske 1983). In previous work, batch culture experiments demonstrated that P limits phytoplankton growth in lake Michigan (e.g. Schelske et al. 1974) and continuous and semicontinuous culture experiments demonstrated importance of nutrient supply ratios in regulating species composition (e.g. Tilman 1977). All previous work has been performed at saturating light intensities with surface of near surface populations. Recent culture work has shown that light may be an important factor in competition experiments (Mur et al. 1977) and that nutrient-light interactions may regulate growth at subsaturating light for certain species (Rhee and Gotham 1981). In contrast to surface populations, the subsurface chlorophyll layer in Lake Michigan is in a relatively high-nutrient, low-light regime, yet in situ growth appears to be important in its development (Moll & Stoermer 1983). Thus, it seems likely that light may influence both community production and species competition. For this reason, we conducted a suite of semicontinuous culture experiments using a subsurface assemblage under a variety of nutrient-light combinations. Here, we describe results from those experiments and suggest there is an important nutrient-light interaction at light intensities found in the vicinity of the subsurface chlorophyll layer and that shade adaptation of subsurface populations may add substantially to the structure of chlorophyll profiles.

FAHNENSTIEL, G.L., C.L. Schelske, and R.A. Moll. In situ quantum efficiency of Lake Superior phytoplankton. Journal of Great Lakes Research 10(4):399-406 (1984).

In situ quantum efficiencies were measured in Lake Superior over a 4-day period in 1978 and on one occasion in 1980. In 1980, experimental artifacts caused by exposing deep phytoplankton to elevated irradiances were minimized by the use of SCUBA divers. The trends of quantum efficiency with depth agreed well with theory. In the nutrient-limited upper portion of the euphotic zone, quantum efficiencies were relatively constant. Maximum quantum efficiencies calculated with downwelling irradiances ranged from 0.041 to 0.069 moles C fixed x Einst abs-1 with a mean maximum quantum efficiency of 0.0538 +/- 0.0025 moles C fixed x Einst abs-1. Maximum quantum efficiencies in morning experiments ranged for 0.041 to 0.053 moles C fixed x Einst abs-1. Correction for scalar irradiance would reduce all quantum efficiencies by 25%.

FREZ, W.A., and P.F. LANDRUM. Species-dependent uptake of PAH in Great Lakes invertebrates. In Polynuclear Aromatic Hydrocarbons: Ninth International Symposium on Chemistry, Characterization, and Carconogenesis, M.W. Cooke and A.J. Dennis (eds.). Batelle Press, Columbus, OH, 291-304 (1984).

No abstract.

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Annual Report for the Great Lakes Environmental Research Laboratory, FY 1983. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 45 pp. (1983).

No abstract.

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Publications by the staff of the Great Lakes Environmental Research Laboratory. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (1983).

No abstract.

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Detailed technical plan for the Great Lakes Environmental Research Laboratory. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 45 pp. (1984).

No abstract.

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Technical plan for the Great Lakes Environmental Research Laboratory. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 73 pp. (1984).

No abstract.

GREENE, G.M. Freeze-up, breakup, and date of maximum ice thickness for the St. Lawrence River--1971-81. NOAA Data Report ERL GLERL-27, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB85-119451/XAB) 19 pp. (1984).

This report summarizes 10 years of ice cover observations (1971-81) for 12 stations along the international section of the St. Lawrence River. For each station and season, the tables list date of freeze-over, date ice free, duration of solid ice cover, maximum ice thickness, and date of maximum ice thickness. Mean dates of freeze-over range from January 1 to January 17, while mean dates of ice free conditions range from February 25 to March 23. The longest mean ice cover duration is 79 days and the shortest is 48 days. The mean maximum ice thickness varies between 23 cm and 56 cm. The mean date of this maximum is as early as February 9 and as late as March 5. Observations were taken during a period that contained 5 winters colder than normal and 5 winters warmer than normal, when compared to an 80-year record of air temperatures.

Hutter, K., G. Salvade, and D.J. SCHWAB. On internal wave dynamics in the northern basin of the Lake of Lugano. Geophysical Astrophysical Fluid Dynamics 27:299-336 (1983).

Data collected from the Lake of Lugano during 3 July to 17 August 1979 are analyzed for internal gravity wave motions. We demonstrate that a two-layer linear model is capable of explaining the internal wave response. A numerical finite difference procedure is used to determine the seiche periods and eigen functions of this model. The computed results (periods and phase differences between station pair interfacial displacements are then compared with the measured data. This comparison demonstrates that four conspicuous internal mode periods can be identified with fair to excellent statistical coherence between data-set pairs and that even higher order modes can be detected but with less statistical confidence. This identification proves that for the Lake of Lugano, no recourse has to be made to multi-layer models that would account for higher order baroclinicity.

Kadlec, R.H., and J.A. ROBBINS. Sedimentation and sediment accretion in Michigan coastal wetlands (U.S.A.). Chemical Geology 44:119-150 (1984).

Sediment transport and accretion rates were studied for three different types of coastal wetlands of Lake Michigan, USA. A forested intradunal wetland (Cranberry Bog No. 1) near Stevensville, Michigan, displayed sediments in the form of detritus, and exported them. Very little sedimentary material entered by streamflow. these features of bottom-land wetlands were confirmed by radioisotope studies on cores, which showed low accretion rates of 210Pb. The mass fluxes were found to range from 0.01 to 0.2 g cm-2 yr-1. The equivalent linear growths are 0.5-9.0 mm yr-1. The suspended material from this wetland entered a filling shrub-bog-lake complex known as Cranberry Bog No. 2. A considerable fraction of the incoming sediments were retained in this intradunal basin wetland. This was confirmed via radioisotope studies, with cores showing higher accretion rates than in the bottom-land wetland. The river delta wetland at Pentwater, Michigan, had little sediment trapping ability. Large amounts of water and suspended materials entered this riverine wetland, but no annual average removal was found. Radioisotope studies of cores at selected locations within this system showed little or no areas. No net annual effect on water quality of the streams as they discharged to Lake Michigan was found. Storm events caused no notable import or export of suspended material. Presumably the sand subsurface flow through this porous soil. These three sand-based coastal wetlands appear to have little net effect on suspended solids. The 210Pb method proved more valuable than 137Cs because of the small depth of occurrence of the latter isotope. Interpretation of isotope profiles required information on acid-fraction-soluble profiles. Results are expressed in terms of mass units, since compaction of cores distorts the linear accretion rate. Delayed transfers of radionuclides appear to have occurred, perhaps as a result of integration of atmospheric inputs by the watersheds. The total activities of 210Pb and 137Cs are well correlated, which indicates particle trapping efficiency ad the primary factor for affecting accumulation of both isotopes.

Krezoski, J.R., J.A. ROBBINS, and D.S. White. Dual radiotracer measurement of zoobenthos-mediated solute and particle transport in freshwater sediments. Journal of Geophysical Research 89(B9):7937-7947 (1984).

Gamma spectroscopy methods have been applied to determine the effects of Stylodrilus heringianus and Pontoporeia hoyi, two freshwater benthic macroinvertebrates, on the reworking of sediments and the transfer of solutes across the sediment-water interface. Natural lake sediments (sieved to remove organisms) and overlying water were contained in temperature-regulated rectangular plastic cells. A submillimeter layer of sediment solids labeled with 137Cs was deposited on the sediment interface while overlying water was spiked with 22Na. After addition of Stylodrilus (oligochaete worms) and Pontoporeia (crustacean amphipods) to these microcosms, the vertical distributions of 137CS (a tracer of particle transport) and 22Na (a tracer of solute transport) were determined at daily to weekly intervals for 3 months by scanning the length of the cells with a well-collimated NaI detector. In cells with Stylodrilus, the 137Cs layer moved downward at a rate that decreased exponentially with time. The displacement of the layer is the result of the conveyor-belt feeding mode of this organism. The rate of marked layer burial is consistent with that of other freshwater annelids (0.18 x 10-5 cm d-1 individual-1 m-2; 11.6oC). The exponential decrease in burial rate is ascribed to uniformly distributed feeding of Stylodrilus within the feeding zone of 4.4 cm. In cells with Pontoporeia, 137Cs activity was smeared downward in time owing to eddy diffusive mixing of sediments over a small range (1-2 cm). In cells without worms, the veneer of Cs active material remained at the interface while the penetration of 22Na into sediments was consistent with diffusion in free solution with small corrections for sediment porosity and sorption (KD = 0.17). The effective diffusion coefficient De for 22Na in this cell (8.2 x 10-6 cm2 s-1) was essentially the same as that for a cell that had been inhabited by worms for 3 weeks and then poisoned with formalin just before addition of 22Na. Thus the presence of biogenically reworked sediments (with pelletized materials and remnant burrow structures) did not affect solute transport. In cells with live Stylodrilus, penetration of 22Na within the feeding zone was considerably more rapid, implying an apparent De twice as high as in cells without worms. Inferences based on the particle reworking results were used to develop an illustrative transport model that includes advective as well as diffusive terms. Advective transport arises from the incorporation of 22Na into pore fluids moved downward as a result of conveyor-belt feeding. The model indicates that within the feeding zone, solute transport is dominated by advection and that the apparent enhancement of De in pure diffusion models is really the result of solute flow induced by particle reworking. In cells with Pontoporeia, De is approximately twice that in control cells. In these cells, 22Na profiles may be treated theoretically without advection.

LANDRUM, P.F., S.M. Bartell, J.P. Giesy, G.J. Leversee, J.W. Bowling, J. Haddock, K. LaGory, S. Gerould, and M. Bruno. Fate of anthracene in an artificial stream: A case study. Ecotoxicology Environmental Safety 8:183-201 (1984).

The fate of anthracene, a representative polycyclic aromatic hydrocarbon, was followed in a large outdoor stream microcosm. The major nonadvective route for the removal of anthracene was photolytic degradation to anthraquinone (half-life 43 min). The anthraquinone also photolyzed rapidly in this shallow stream system. Excluding the plastic channel liner, the sediment acts as the major sink for anthracene, absorbing 0.2% of the 14-day input dose. The periphyton community was the second most important sink, absorbing 0.04% of the input dose. All other compartments were of significantly less importance on a mass basis. Anthracene (11 mg liter-1) caused photo-induced 100% mortality of the bluegill sunfish in 9 hr in the upstream reach. Fish at the downstream station survived for ~26 hr and all died within 1 hr of each other. Other organisms, clams and dragonfly larvae, started to die off toward the end of the 14-day input period.

LANDRUM, P.F., S.R. Nihart, B.J. EADIE, and W.S. GARDNER. Reverse-phase separation method for determining pollutant binding to Aldrich humic acid and dissolved organic carbon of natural waters. Environmental Science and Technology 18:187-192 (1984).

A reverse-phase separation technique was used to determine the binding of 14C-radiolabeled organic pollutants [benzo(a)pyrene, anthracene, biphenyl, p,p'-DDT, 2,4,5,6',4',5'-hexachlorobiphenly, 2,5,2',5'-tetrachlorobiphenyl, and bis(2-ethylhexyl) phthalate] to humic materials in aqueous solution. The humic-bound pollutant was separated from the "freely dissolved" pollutant by using a Sep-Pak C-18 cartridge; humic-bound pollutant passed through, while the unbound pollutants were retained by the column. The partition coefficient (grams of pollutant bound/gram of organic carbon)/(grams of pollutant freely dissolved/milliliter) did not depend on pollutant concentration but was inversely proportional to the concentration of dissolved organic carbon (DOC) in solution. At low DOC (1-2 mg of Aldrich humic acids L-1), the partition coefficient was approximately equal to the octonal-water partition coefficient and inversely proportional to water solubility. The partition coefficient for natural waters was approximately 1 order of magnitude lower than that determined for the Aldrich humics at similar DOC concentrations. The reverse-phase separation was simple and rapid and gave results similar to dialysis techniques.

LANG, G.A. The Mineral River--A unique tributary chloride load to Lake Superior. Journal of Great Lakes Research 9(4):584-587 (1983).

The Mineral River contributes a significant amount of chloride to Lake Superior, more than one-third of the total U.S. tributary input. This unique discharge is attributed largely to the mine dewatering process of the White Pine Copper Company. Chloride concentrations as high as 2,000 mg/L have been recorded at the mouth of the Mineral River. The impact of this discharge on Lake Superior is not known; however, it is postulated that increased chloride concentrations may enhance the introduction and adaptation of marine organisms into the Great Lakes.

LANG, G.A. Update of U.S. Great Lakes tributary loadings, 1979-80. NOAA Technical Memorandum ERL GLERL-54, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB85-171528/XAB) 41 pp. (1984).

This report presents estimated annual loads to the Great Lakes from U.S. tributaries for Water Years 1979 and 1980. Total, monitored, and diffuse loads are tabulated for each of seven categories: total phosphorus, soluble orthophosphorus, suspended solids, chloride, total nitrogen, ammonia nitrogen, and nitrate (+ nitrate) nitrogen. This study updates two previous reports that give the load estimates for Water Years 1975-78.

Lehman, J.T., and D. SCAVIA. Measuring the ecological significance of microscale nutrient patches. Limnology and Oceanography 29(1):214-216 (1984).

No abstract.

LESHKEVICH, G.A., and N.J. Reid. Airborne measurements of freshwater ice albedos. Proceedings, Eighteenth International Symposium on Remote Sensing of Environment, Vol. 3, Paris, France, October 1-5, 1984. 1677-1687 (1984).

The albedos of open water and four major freshwater ice types were measured under clear skies from a Sikorski-built U.S. Coast Guard helicopter at an altitude of approximately 300 m. The instrument used for the measurements was a programmable band spectral radiometer (PROBAR) built by Moniteq, Ltd., of Concord, Ontario. The instrument is capable of making simultaneous radiance and irradiance measurements in the visible and near-infrared (400-1100 nm) range. Measurements were made on two consecutive days (March 26,17, 1984) over large uniform ice surfaces on southern Lake Huron. Three passes were made over each of five surface types: open water, refrozen slush, densely consolidated brash, large floes in a black ice matrix, and skim ice. With a 15o field of view, the surface area measured was approximately 80 m in diameter. Smearing of the footprint due to the forward motion of the aircraft was less than 7 m owing to the radiometer's fast scan rate and the helicopter's average 35 kn air speed. Because of possible attenuation by the helicopter's rotor blades and shading by the fuselage, irradiance measurements were made at ground level between airborne measurements on the first day and before and after airborne measurements on the second day. The three sets of radiance measurements were averaged for each type and machine processed with the irradiance data, resulting in reflectance values from 430-1100 nm for each surface type.

Leversee, G.J., P.F. LANDRUM, J.P. Giesy, and T. Fannin. Humic acids reduce bioaccumulation of some polycyclic aromatic hydrocarbons. Canadian Journal of Fisheries and Aquatic Sciences 40(2):63-69 (1983).

In laboratory studies, Daphnia magna were exposed for 6 h to five polycyclic aromatic hydrocarbons (PAH) (0.1-2.0 mg/L) in water with and without Aldrich humics (2 mg DOC/L). Compared to results in nonhumic water, accumulation of PAH by Daphnia in water with humics was significantly reduced for benzo[a]pyrene (-25%) while it was increased for methylcholanthrene (+210%). Humics did not significantly alter Daphnia accumulation of anthracene, dibenzanthracene, or dimethylbenzanthracene. In additional studies, humics reduced Daphnia accumulation of benzo[a]pyrene (B[a]P) over a range of (B[a]P) concentrations (1.1-5.4 mg/L) exceeding the reported limit for water solubility (1.1-1.2 mg/L). Humics consistently increased Daphnia accumulation of methylcholanthrene (MC) over a range of humic concentrations from 0.2 to 10.0 mg DOC/L. Particulates and DOC (10-12 mg TOC/L) occurring naturally in two South Carolina streams reduced Daphnia accumulation of B[a]P by 38-66%, with about 40% of the overall reduction attributable to DOC. We conclude that dissolved refractory organics may significantly affect bioavailability and environmental transport of some PAH in fresh waters.

LIU, P.C. A representation for the frequency spectrum of wind-generated waves. Ocean Engineering 10(6):429-441 (1983).

This paper proposes the follwoing generalized representation for a wind-wave frequency spectrum: where is the variance of the surface displacement; is the frequency of the spectral peak; and , i = 1,2,3, are dimensionless parameters that can be determined from the internal spectral paramenters of a given spectrum. When applied to 234 sets of wave spectra recorded in the Great Lakes, this representation has been relaistic, accurate, and capable of representing widely varied wave processes. The are clearly related to wave growth processes; they are large during early growth, decrease as waves grow, and reach approximate equilibrium when waves are fully developed.

LIU, P.C. An iteration problem. SIAM Rev. 26:279 (1984).

No abstract.

LIU, P.C., D.J. SCHWAB, and J.R. BENNETT. Comparison of a two-dimensional wave prediction model with synoptic measurements in Lake Michigan. Journal of Physical Oceanography 14(9):1514-1518 (1984).

We compare results from a simple parametric, dynamical, deep-water wave prediction model with two sets of measured wave height maps of Lake Michigan. The measurements were made with an airborne laser altimeter under two distinctly different wind fields during November 1977. The results show that the model predicted almost all of the synoptic features. Both the magnitude and the general pattern of the predicted wave-height contours compared well with the measurements. The model also predicts the direction of wave propagation in conjunction with the wave height map, which is useful for practical ship routing and con be significantly different from the prevailing wind direction.

McCall, P.L., J.A. ROBBINS, and G. Matisoff. 137Cs and 210Pb transport and geochronologies in urbanized reservoirs with rapidly increasing sedimentation rates. Chemical Geology 44:33-65 (1984).

Sedimentation rates have been measured in three reservoirs in northeastern Ohio., U.S.A., by means of 137Cs and 210Pb geochronologies, volumetric surveys and varve counting. These various methods, while only partially overlapping for each reservoir, show dramatic (three-fold) increases in rates of sediment accumulation in each system between about 1940 and 1977. Mass sedimentation rates are very nearly proportional to the size of the population in the region and possess a doubling time of roughly 19 yr. In these systems with changing sedimentation rates, the preferred model for use with 210Pb geochronologies is one which assumes a constant activity of material added to surface sediments. In systems possessing large (watershed)/(reservoir area) ratios, increasing erosion is evidently accompanied by a proportionate increase in the erosion of excess 210Pb. High near-surface activities of 137Cs are due to system integration effects with time constituents the order of 10 yr. to a few decades. Total accumulation of fallout 137Cs and excess 210Pb far exceed direct atmospheric loadings, thus indicating the importance of watershed contributions and implying annual retention of the radionuclides in the reservoirs of between ~ 15% and ~ 80%. In Lake Rockwell, sedimentary fluxes of Zn, Pb and Cu have increased with time. The flux of Cu in particular has increased very markedly since 1970, and concentrations are high in surface materials due in large part to addition of CuSO4, and algicide, to the water. Because of increased rates of sedimentation, the remaining useful life of Lake Rockwell has decreased from 203 to 67 yr., while the remaining useful life of Mayfair Lake is now less than 5 yr.

McCORMICK, M.J., and S.J. TARAPCHAK. Uncertainty analysis of calculated nutrient regeneration rates in Lake Michigan. Canadian Journal of Fisheries and Aquatic Sciences 41(1):206-211 (1984).

First-order uncertainty analysis of the following error sources was used to estimate errors in a mass balance calculation of regeneration rates for phosphorus, silica, and nitrogen at an offshore station in Lake Michigan; (1) precision of nutrient measurement, (2) vertical eddy diffusivity, (3) atmospheric loading, (4) primary production, (5) nutrient to carbon ratio, and (6) onshore-offshore nutrient transport. Approximately 80% of the variance for phosphorus regeneration was due to uncertainty in the phosphorus to carbon ratio, and more than 90% of the variance for silica and nitrogen regeneration was due to the onshore-offshore transport term. Calculated nutrient regeneration rates can be meaningful only if uncertainty due to advection and cellular stoichiometry are minimized.

Meyers, P.A., M.J. Leenheer, B.J. EADIE, and S.J. Maule. Organic geochemistry of suspended and settling particulate matter in Lake Michigan. Geochimica et Cosmochimica Acta 48:443-452 (1984).

Organic matter contained in particulate matter in Lake Michigan waters and sediments has been characterized by C/N ratios and by distributions of biomarker fatty acids, alkanols, sterols, and aliphatic hydrocarbons. Differences in organic constituents of particulate matter from various depths and distances from shore indicated a complex interaction of production, transformation, and destruction of the organic matter contained in sinking particles. Near-surface material contains important contributions of land-derived organic matter, presumably of eolian input. Midwater particles have predominantly aquatic organic material of algal origin. At the sediment-water interface, selective suspension of the finer fractions of surficial sediments enriches bottom nepheloid layers with these sediment size classes. As a result, near-bottom particulate matter has an aquatic biomarker character. Organic matter associated with sinking particles undergoes substantial degradation during passage to the bottom of Lake Michigan, and aquatic components are selectively destroyed relative to terrigenous components.

Milliken, W.G. Reflections on research. Journal of Great Lakes Research 10(1):2 (1984).

No abstract.

NALEPA, T.F., and M.A. QUIGLEY. Abundance and biomass of the meiobenthos in nearshore Lake Michigan with comparisons to the macrobenthos. Journal of Great Lakes Research 9(4):530-547 (1983).

The meiobenthos of nearshore southeastern Lake Michigan was quantified by taking cores from three depths (11, 17, and 23 m) at monthly intervals from May to November 1976-79. Total meiobenthic abundance ranged from 69,700/m2 to 1,300,000/m2 and total biomass ranged from 0.03 to 0.87 g/m2. Nematodes accounted for 80% of all individuals and 66% of the biomass. Most of the major groups peaked in late spring/summer, but some peaked in early spring and fall. With the exception of nematodes, mean annual densities varied from two-fold to twelve-fold at a given station. Harpacticoids, tardigrades, and ostracods tended to be more abundant at the deeper depths, while cyclopoids and cladocerans were less abundant. There was no consistent relationship between sampling depth and the abundance of nematodes and rotifers. Temporal and spatial variation in many of the groups appeared related to changes in the amount of bottom detritus. The overall macrobenthos:meiobenthos biomass ratio was 15:1 and ranged from 5:1 to 45:1 on an annual basis.

NORTON, D.C. A comparison of precipitation averages as estimators of overbasin precipitation. GLERL Open File Report, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (1984).

No abstract.

Oris, J.T., J.P. Giesy, P.M. Allred, D.F. Grant, and P.F. LANDRUM. Photoinduced toxicity of anthracene in aquatic organisms: An environmental perspective. In The Biosphere: Problems and Solutions, T.N. Veziroglu (ed.). Elsevier Science Publishers, Amsterdam, The Netherlands, 639-658 (1984).

The toxicity of anthracene, common polycyclic aromatic hydrocarbon (PAH), has been assessed in a variety of aquatic organisms under environmentally realistic conditions. In the presence of natural or simulated sunlight anthracene was acutely toxic, at concentrations within aqueous solubility limits, to freshwater zooplankton, insect larvae, and fish. Less than 15 min was required for 50% immobilization of Daphnia pulex at 1.2 mg anthracene/l under natural sunlight (UV-B, 310 +/- 34 nm, = 484 mW/cm2). Culicid mosquito larvae were also sensitive to anthracene phototoxicity with a 24 hr LC-50 value of 26.8 mg/l at a solar UV intensity five times less than summer maximum in Michigan. A 96 hr LC-50 value of 11.9 mg anthracene/l was determined for a natural population of juvenile bluegill sunfish at a solar UV intensity equivalent to a depth of 0.6 m in typical eutrophic north-temperate lake. A freshwater green alga was not adversely affected by the light-anthracene combination. These findings are in contrast to the previously reported non-toxicity of anthracene to aquatic organisms. Evidence exists which suggests that anthracene is only one of many PAH that can cause photoenhanced toxicity, and concentrations of these compounds are expected to increase in surface waters as a result of increased use of fossil-fuel for heat and energy. The potential environmental consequences of increased loading of PAH in freshwater and marine systems are discussed. We conclude that solar UV radiation is an environmental parameter which must be accounted for when assessing the toxicity of PAH to aquatic organisms.

Paffenhofer, G.A., and W.S. GARDNER. Ammonium release by juveniles and adult females of the subtropical marine copepod Eucalanus pileatus. Journal of Plankton Research 6(3):505-513 (1984).

Release rates of ammonium by nauplii, copepodid stages (CII and CIV) and adult females of the marine copepod Eucalanus pileatus at 0l1 and 3.0 mm3 1-1 of the diatom Thalassiosira weissflogii were determined at 20oC. When food was abundant, animals of all stages released ammonium at similar rates per unit ash-free dry weight [24-35 nmol NH4 (mg AFDW)-1 h-1 on average]. At low food levels, CIVs and adult females released ammonium significantly more slowly than did the nauplii of CIIs [28 and 24 versus 51 and 50 nmoles (mg AFDW)-1 h-1]. Because they weighed less (50%), low-food nauplii and CIIs had higher calculated weight-specific excretion rates, than high-food ones of the same stage but release rates per copepod were similar in the two food regimens. In contrast to the early life stages, the CIVs and adult females released less ammonium per copepod in the low-food than in the high-food environment.

QUIGLEY, M.A. Freshwater macroinvertebrates. Journal of Water Pollution Control Federation 56:774-780 (1984).

No abstract.

QUINN, F.H., and T.E. CROLEY. Climatic basin water balance models for Great Lakes forecasting and simulation. Proceedings, Fifth Conference on Hydrometeorology, American Meteorological Society, Boston, MA, 218-223 (1983).

No abstract.

ROBERTSON, A., and D. SCAVIA. North American Great Lakes. In Lakes and Reservoirs, F.B. Taub (ed.). Elsevier Science Publishers, Amsterdam, The Netherlands, 135-176 (1984).

No abstract.

SAYLOR, J.H., and G.S. MILLER. Investigation of the currents and density structure of Lake Erie. NOAA Technical Memorandum ERL GLERL-49, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB84-140334) 92 pp. (1983).

Currents and water temperatures were recorded at a large-scale grid of fixed moorings in Lake Erie from May 1979 through June 1980. Thermistor chains were used to record the complete development and decay of central basin stratification. First a fragile stability develops, which is very susceptible to high wind stress. For example, strong wind impulse in late May 1979 completely mixed the central basin and postponed the development of stable stratification for 3 weeks. Currents measured in the lower half of the central basin water column were mostly return flows (beneath the surface wind drift) driven by the surface pressure gradient. We often observed a complex system of Lake Erie circulation gyres as predicted by models, although we noticed a frequent tendency for one of the central basin gyres to become dominant and envelop the whole basin in either uniform clockwise or anticlockwise flow. It is not clear why one of the circulation cells grows as opposed to the others. The currents appear to be somewhat more barotropic than predicted by full Ekman layer current models. Tidal-like currents driven by the longitudinal seiches of Lake Erie control the island-filled passages between the western and central Lake Erie basins, with currents across the whole island chain very much in phase. Processes of hypolimnion volume entrainment are suggested from the central basin temperature recordings. Large quantities of water were exchanged between the central and eastern basins over long periods; this occurred mostly after the shallow ridge that separates them had become unstratified. These and other topics are discussed as we explore the large data set generated from the experiment.

*SAYLOR, J.H., and G.S. MILLER. Studies of lake-scale currents and temperature distributions. In Technical Assessment Team Report on the 1978-79 Lake Erie Intensive Study, D.E. Rathke et al. (eds.). Ohio State University, Columbus, OH, 27 (1984).

Not available from GLERL.

SCAVIA, D., G.L. FAHNENSTIEL, J.A. Davis, and R.G., Jr. Kreis. Small-scale nutrient patchiness: Some consequences and a new encounter mechanism. Limnology and Oceanography 29(4):785-793 (1984).

Semicontinuous cultures of Lake Michigan algal assemblages were run at 0.15 day-1 dilution rates under P limitation for 41 days. In control cultures, nutrients were supplied to the entire culture once per day. In patch cultures, 10% of the cultures received a high concentration 10-min pulse each day. Patch and control cultures received equal nutrient flux and achieved equal biomass levels; however, their species composition was different. Patch cultures were dominated by the filamentous blue-green alga Schizothrix calcicola and control cultures were dominated equally by S. calcicola, Nitzschia acicularis, and a group of phytoflagellates. These results, as well as shifts in subdominants, demonstrate the effect of small-scale, short term nutrient patches on species composition. Similar patch and control unialgal cultures revealed lower cell nutrient quotas for patchy cultures. Microvideographic observations of Daphnia magna suspended in three concentrations of Chlamydomonas sp. allowed quantification of rates at which algal cells. Outwashing release rates of presumably unharmed cells increased from 31 to 71% of the collection rate as food concentration increased. It appears that algal outwashing is a significant mechanism for eliminating excess food. An important implication is the potential algal nutritional consequence of this very close nondestructive encounter.

Schelske, C.L., B.J. EADIE, and G.L. Krausse. Measured and predicted fluxes of biogenic silica in Lake Michigan. Limnology and Oceanography 29:99-110 (1984).
Diatom production in the offshore water of Lake Michigan is limited by silica supplies in late summer and con be predicted from the seasonal disappearance of silica from the trophogenic zone. Biogenic silica fluxes obtained from sediment trap collections were compared with fluxes predicted from the silica disappearance model. Measured and predicted fluxes were in good agreement for offshore stations, but at stations closer to shore measured fluxes were 2-3 times greater than predicted fluxes. Sediment trap and water chemistry data show that little of the diatom production is dissolved in the water column. Therefore, greater than predicted fluxes at nearshore locations were attributed to new silica supplied from upwellings, tributary inputs, and recycling and resuspension in nearshore sediments. The good agreement between measured and predicted fluxes in offshore waters shows that biogenic silica fluxes may be useful in determining the collecting efficiency of sediment traps.

SCHWAB, D.J. Numerical simulation of low-frequency current fluctuations in Lake Michigan. Journal of Physical Oceanography 13(12):2213-2224 (1983).

Two simple numerical models have been used to study the low-frequency (<0.6 cpd) current oscillations observed in Lake Michigan in order to learn more about what really limits our ability to simulate currents in large lakes. Both are based on the barotropic vorticity equation with the rigid-lid approximation. One model used observed wind to calculate the time-dependent response of the lake for eight months in 1976. The results agree reasonably well with observed currents, but only in the frequency range corresponding to the maximum energy in the forcing function, approximately 0.125-0.3 cpd. Over this frequency range, peaks in the energy spectrum of the forcing function also occur in both the model response and the observed currents at the same frequencies. At lower and higher frequencies, the model underestimates the observed kinetic energy of the currents. The second model calculates the response of the lake to purely oscillatory wind forcing frequency. From 0.125 to 0.3 cpd, the spatial structure of the response is relatively insensitive to changes in forcing frequency. The response to a north-south oscillatory wind stress resembles a free topographic wave consisting of two counterrotating gyres in the southern basin of the lake, but is more complicated in the northern part. When compared to previous analytic and numerical studies of steady-state circulation, the steady-state (zero frequency) response is found to be consistent with Ekman dynamics for realistic values of linearized bottom stress. the results indicate that the barotropic rigid-lid model can simulate observed current fluctuations only in the 0.125-0.3 cpd frequency range. Over this range, the average response of the lake is nonresonant, showing no peaks in lakewide average kinetic energy. At higher and lower frequencies, baroclinicity and nonlinear effects may have to be included in order to improve the model results.

SCHWAB, D.J., J.R. BENNETT, and E.W. LYNN. A two-dimensional lake wave prediction system. NOAA Technical Memorandum ERL GLERL-51, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB84-231034) 77 pp. (1984).

This report describes a series of computer programs that can be sued to forecast wave height, period, and direction for any part of the Great Lakes. The programs only require the user to specify the overlake wind forecast.

SCHWAB, D.J., J.R. BENNETT, P.C. LIU, and M.A. Donelan. Application of a simple numerical wave prediction model to Lake Erie. Journal of Geophysical Research 89:3586-3592 (1984).

A parametric dynamical wave prediction model has been adapted and tested against semianalytic empirical results for steady conditions in a circular basin and extensive fiel measurements of wave height, period, and direction. The adapted numerical model accurately predicts the directional spreading of waves for uniform steady wind that Donelan (1980) had predicted analytically for fetch-limited waves. When the model was applied to the central basin for Lake Eire and the results compared to observations of wave height and period (at two points in the lake) and direction (at one point), results for wave height and direction estimates were excellent compared to measurements at a research tower off the southern shore, but computed wave heights were lower than observed at a weather buoy in the western part. The model somewhat underestimated wave periods at both places. Thus, with locally measured wind data as input, the model estimates wave height and direction well and wave period acceptably.

SCHWAB, D.J., J.R. BENNETT, and E.W. LYNN. Pathfinder--A trajectory prediction system for the Great Lakes. NOAA Technical Memorandum ERL GLERL-53, Great Lakes Environmental Research Laboratory, Ann Arbor, MI (PB85-115335/XAB) 37 pp. (1983).

This report describes a series of computer programs that can be used interactively to simulate currents and particle trajectories on the Great Lakes. The user of the programs supplies meteorological data and initial particle locations. The programs allow the user to examine predicted currents, particle locations, and particle paths in several different formats.

SCHWAB, D.J., G.A. Meadows, J.R. BENNETT, H. Schultz, P.C. LIU, J.E. CAMPBELL, and H.H. Dannelongue. The response of the coastal boundary layer to wind and waves: Analysis of an experiment in Lake Erie. Journal of Geophysical Research 89:8043-8053 (1984).

Wind, waves, currents, and water levels were measured near Lake Erie's southeastern shore during fall 1981. Data were recorded continuously at a wave research tower 6 km offshore at three Waverider buoys deployed around the tower and at three current meter moorings along a transect between the tower and the shore. During the four storm episodes, wave and current data were also recorded from a dense array of instruments along a transect across the surf zone. A statistical analysis of the deep water data was performed, and histograms of meteorological parameters, wave parameters, and water level slope were plotted as a function of wind direction. The atmospheric boundary layer was usually unstable; on the average, the water was 2-3oC warmer than the air. This was true for all wind directions. At the tower the highest waves were associated with the greatest fetch distances to the WSW and WNW directions. The longest period waves were also associated with these wind directions. The mean water levels slope was opposite the mean wind direction. This discrepancy is most likely due to small leveling errors in the water level gages. The variation of currents with wind direction was also examined. The currents are strongest when the winds are from the west, the quadrant with the strongest wind speeds. However, there are strong currents (5-10 cm/s) for all wind directions. The deep water currents are basically shore parallel, with the onshore/offshore component averaging 39% of the root mean square longshore component. Analysis of the four storm episodes reveals the influence of the offshore currents on the flow regime within the surf zone. Quantitative estimates of the longshore momentum balance outside the surf zone, the radiation stress, wind stress, and bottom stress terms all have comparable effects and are usually larger than the acceleration and pressure gradient terms. In between, there is evidence of longshore flow reversals in the breaker zone and the effect of seiche-induced offshore currents on the near shore flow regime.

SCHWAB, D.J., and J.A. MORTON. Estimation of overlake wind speed from overland wind speed: A comparison of three methods. Journal of Great Lakes Research 10:68-72 (1984).

Meteorological data gathered by buoys in Lake Erie and recorded at overland weather stations were used to test three different methods for determining overlake wind speed as a function of overland wind speed and the difference between overland air temperature and water temperature. The overall root mean square differences between estimated and observed overlake wind speed ranged from 2.02 to 2.11 m s-1. Overall correlation coefficients ranged from 0.63 to 0.69. These values are close to the best values possible for a simple statistical formula relating overlake wind speed to overland wind speed and air-water temperature difference. The conclusion is that statistical methods for determining overlake wind speed from overland wind speed have not improved markedly in over a decade and new methods are called for. It is also shown that for the Great Lakes, as opposed to the open sea, air-water temperature difference is a significant factor in determining overlake from overland wind speed.

SCHWAB, D.J., and D.B. RAO. Barotropic oscillations of the Mediterranean and Adriatic Seas. Tellus 35A:417-427 (1983).

The periods and structures of several of the lowest barotropic free modes of oscillation of the combined Mediterranean-Adriatic system are computed. The computations take account of the two-dimensional structure of the Mediterranean-Adriatic system, the actual bottom topography, and the earth's rotation. To separate the effects of each of these factors, calculations are carried out first for uniform depth, then for variable depth but no rotation, and then for variable depth and rotation. The results show that the effect of variable bottom topography is more important than rotation. the computed periods for the lowest four modes of the Mediterranean Sea are 38.5 h, 11.4 h, 8.4 h, and 7.4 h. In addition, the periods and structures of several of the lowest modes of the Adriatic Sea are computed without rotation on a high-resolution grid. The location of the mouth of the Adriatic Sea is determined by the combined Mediterranean-Adriatic calculation. By imposing the mouth in the proper location, we found that the computed periods of the lowest modes agree with observed periods. The computed periods of the three lowest modes in the Adriatic Sea are 21.9 h, 10.7 h, and 6.7 h.

SONZOGNI, W.C., A. ROBERTSON, and A.M. Beeton. Great Lakes management: Ecological factors. Environmental Management 7(6):531-541 (1983).

Although attempts to improve the quality of the Great Lakes generally focus on chemical pollution, other factors are important and should be considered. Ecological factors, such as invasion of the lakes by foreign species, habitat changes, overfishing, and random variations in organism populations, are especially influential. Lack of appreciation of the significance of ecological factors stems partly form the inappropriate application of the concept of eutrophication to the Great Lakes. Emphasis on ecological factors is not intended to diminish the seriousness of pollution, but rather to point out that more cost-effective management, as well as more realistic expectations of management efforts by the public, should result from an ecosystem management approach in which ecological factors are carefully considered.

SONZOGNI, W.C., and W.R. Swain. Perspectives on human health concerns from Great Lakes contaminants. In Toxic Contaminants in the Great Lakes, J. O. Nriagu and M.S. Simmons (eds.). John Wiley and Sons, New York, NY, 1-29 (1984).

Although trace toxic chemical contaminants affect all levels of the Great Lakes ecosystem, they are considered a critical problem mainly because they pose a threat to human health. For example, certain chemical substances have accumulated in Great Lakes fish to the extent that the concentration in fish is several hundered thousand times higher than in the water. This has prompted advisories to be posted in many Great Lakes states warning that eating a certain Great Lakes fish may be a health hazard. In some cases, the fishery has even been closed. The purpose of this chapter is to review the basis for health concerns, particularly with regard to PCBs, and to evaluate the level of risk encountered.

STUBBLEFIELD, B., and J.R. BENNETT. Preliminary report on GLERL's ice dynamics simulation model. GLERL Open File Report, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 52 pp. (1984).

No abstract.

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