Hypolimnetic Oxygen Deficit Research Articles

Detecting the Increased Eutrophication Rate of Douglas Lake, Michigan: the Relative Areal Hypolimnetic Oxygen Deficit Method

ABSTRACT We use data gathered since 1971 on Douglas Lake, Michigan to illustrate the use of temperature and depth adjusted oxygen deficits to assess changes in the rate of lake eutrophication. The method of calculation with adjustments is presented. By comparing different hypolimnia in the multidepression lake, we show that localized lakeshore land use produces regional patterns of production that are detected by comparison of oxygen deficits. For some lake regions, the increase in oxygen deficit has had a linear doubling since 1971. Using historical data, this rate of change is much greater than for the previous 50 years. The oxygen deficits in the lake region farthest from lakeshore development averaged 60% of those in the region nearest lakeshore development.

Thermal and trophic stability of deeper Maine lakes in granite watersheds impacted by acid deposition

Acid deposition can lead to lake and watershed acidification, increases in lake transparency, and reductions in thermal stability and hypolimnetic oxygen deficits. On the basis of lake surveys during August‐September 1985, we determined to what extent the deeper (maximum depth zm > 17 m) Maine lakes in acid‐sensitive granitic watersheds have registered changes in temperature and oxygen stratification, as compared to 1938–1942, when G. P. Cooper performed the earliest scientific surveys of the state's lakes. After correcting for small but geographically consistent interannual differences in summer hypolimnetic temperatures related to spring turnover, and weather‐dependent differences in mixed layer depth, there has been no significant change in thermal stratification in these Maine lakes over approximately 43 years. On the basis of specific historical contrasts in the late summer metalimnetic, hypolimnetic, and bathylimnetic oxygen concentrations there has been no significant change in lake trophic state or transparency.

Alkalinities of Maine lakes: Are they really changing?

Alkalinity changes between 1938–1944 and 1985 were evaluated for Maine lakes (zmax ≳ 15 m) in granitic watersheds. Modern (late summer 1985) Gran alkalinities for the hypolimnion were compared with historical alkalinities computed using: urn:x-wiley:00243590:media:lno19903561238:lno19903561238-math-0001 where pH(T) is the historic reported colorimetric pH at each hypolimnetic sampling depth and temperature, pK'1(T) the temperature‐dependent negative logarithm of the first dissociation constant for carbonic acid, and H2CO3* represents initial CO2 at last spring overturn, plus the change in CO2 associated with the hypolimnetic oxygen deficit developed over summer (estimated from the historic oxygen data). With modern data for representative Maine lakes and historical (1932) data on dissolved gases reported for northern Wisconsin lakes, the apparent respiratory quotient relating ΔCO2 to ΔO2 = 0.92. The above model yields alkalinity estimates with a relative root‐mean‐square (RMS) error of ∼15%.The alkalinities of the Maine lakes have increased by 15–50 µeq liter−1 (>30%) since the original surveys. Lake alkalization is not the result of differences in antecedent weather, since abnormally dry weather predating 1942 would have acted to elevate alkalinities.

Hypolimnetic oxygen consumption in Lake Taupo, New Zealand: A preliminary assessment

Abstract The water quality of Lake Taupo is of great national importance to New Zealand, but development pressures in the catchment require attention to prevent organic enrichment of the water. Observations on the lake were made during 1986–87 to relate hypolimnetic oxygen consumption to organic carbon input from the phytoplankton (14C photosynthetic production) and to the amount of sedimenting phytoplankton determined in sediment traps. There is some degree of hypolimnetic oxygen deficit, even at least lake stability, and so no excess supply of oxygen by physical means exists to balance any enhanced organic input. Sedimentation rate varied greatly throughout the year. It was mainly controlled by the onset of stratification which radically affected the heavily frustuled diatoms dominant at this time. The species present also influenced sedimentation at other times but to a lesser extent. Both allochthonous input of organic material and nitrification are significant additions to phytoplanktonic production for oxygen consumption, but both amounts are uncertain at present and could be greater than estimated. Total organic input would probably have to approximately double to start deoxygenation of the sediment at maximum stability and so induce a radical change in the ecosystem.

Estimates of hypolimnetic oxygen deficits in ponds

Shallow tropical integrated culture ponds in the Pearl River Delta. China, have been found to stratify almost daily, with high organic loadings and dense algal growth. The dissolved oxygen (DO) concentration is super-saturated in the epilimnion and is under 2 mg/l in the hypolimnion (>lm). The compensation depth corresponds to twice the Secchi disk depth ranging from 50 to 80cm. As a result, little or no net oxygen is produced in the hypolimnion (> 1 m). The low DO concentration in the hypolimnion causes organic materials, such as unused organic wastes and senescent algae cells, to be incompletely oxidized, since the rate of oxygen consumption by oxidable matter in water is dependent on the dissolved oxygen concentration in water. This material becomes the source of hypolimnetic oxygen deficits (HOD) which can drive whole pond DO to a dangerously low level, should sudden destratification occur. An improved estimate of hypolimnetic oxygen deficits is introduced in this article, and the advantages of this method are discussed.

Effects of oxygen transport on the areal hypolimnetic oxygen deficit

Using a modified flux gradient technique, transmetalimnetic oxygen transport was evaluated in Lakes Mendota and Delavan, two eutrophic Wisconsin basins featuring moderate depth (17 < zmax < 25 m), good wind exposure, and classic clinograde oxygen profiles. The biweekly fluxes intensified between mid‐May and late July 1972, mainly on account of seasonal steepening of the metalimnetic O2 gradients. Fluxes also increased sharply during windy intervals characterized by accelerated transmetalimnetic heat fluxes. The fluxes across the lower epilimnetic boundary exceed those across the lower metalimnetic boundary; this differential is consistent with the metalimnion's role as an oxidation zone in these turbid lakes. The vertical fluxes are a large but variable (over time) fraction of the net areal oxygen deficit in both lakes, thus complicating statistical analysis of seasonal and intergenerational trends in lake productivity using the areal hypolimnetic oxygen deficit method. Even after correcting for the effects of O2 transport, the deficit in Lake Mendota exceeds that in Delavan following the onset of hypolimnetic anoxia in the shallower lake. This difference likely results, in part, from transmetalimnetic fluxes of reducing substances (CH4, NH3, etc.) into the epilimnion.

Spatial and temporal variation in hypolimnetic oxygen deficits of a multidepression lake

Marked differences in areal hypolimnetic oxygen deficits were found among three depressions of a single lake. These differences were similar to those measured 11 yr before and indicate that regional patterns of nutrient input, production, and eutrophication exist. The patterns are related to lakeshore land use and development. The rate of eutrophication has accelerated across the lake over the 11‐yr span. This increase in eutrophication rate would not have been detected had not the hypolimnetic oxygen deficit data also taken into account the differences in hypolimnetic temperatures between the two studies. In fact, without considering temperature, opposite conclusions would have been reached; i.e. that the rate of eutrophication was lessening.

Vertical Transport of Oxygen into the Hypolimnion of Lakes

Rates of vertical transport of oxygen into the hypolimnion were calculated by multiplying the vertical eddy diffusivity coefficients, determined from the heat budget, by the measured gradients in oxygen concentration. In 12 lakes, transport ranged from 0 to 70 mg O2∙m−2∙d−1and was insensitive to the depth defining the upper boundary of the hypolimnion. Oxygen was transported into the hypolimnion of lakes with a thinner hypolimnion and out of the hypolimnion of lakes with a thick hypolimnion. Transport averaged 4% of the measured total rate of hypolimnetic oxygen depletion and < 10% of the depletion rate in individual strata. Pooling these results with published estimates of oxygen gradients and eddy diffusivities suggests that in lakes with different trophic status (phosphorus levels 4–100 μg∙L−1) and size (areas from 0.4 to 70 km2), vertical oxygen transport accounts for less than 15% of the hypolimnetic oxygen deficit. Oxygen depletion models will gain relatively little precision by including a vertical transport flux parameter.

Decomposition of Seston in the Hyolimnion

In 12 lakes a significant fraction of the hypolimnetic oxygen deficit was produced by the respiration of seston in the hypolimnetic water column. Mean summer seston respiration rates ranged between 4 and 80 mg O2∙m−3∙d−1. Rates of seston respiration were proportional to the in situ water temperature and to the concentration of Chlorophyll a. The amount of oxygen consumed in the water column and the fraction of the total oxygen deficit produced by sestonic respiration were correlated with the amount of phosphorus sedimented from the epilimnion. Fifteen to 66% of the total oxygen consumption occurred in the water column of the hypolimnion. Seston respiration was a larger proportion of the total respiration in the hypolimnion of lakes with a thick hypolimnion than in lakes with a shallow hypolimnetic water column.

EVALUATION OF A PREDICTION METHOD FOR OXYGEN INJECTION REQUIREMENTS IN RICHARD B. RUSSELL LAKE

ABSTRACT To maintain an oxygen concentration of at least 6 mg/L in the discharge, an oxygen injection system was designed for the Corps of Engineers peaking hydropower project on the 10,785 ha Richard B. Russell Lake (Georgia-South Carolina). To aid in the operation of the oxygenation system, a mathematical model was developed to compute the amount of oxygen required to meet the desired discharge standard. Factors considered by the model included the outflow rate, oxygen depletion rates, hypolimnetic volume, oxygen deficit, selective withdrawal patterns and oxygenation efficiency. Oxygen depletion rates and hypolimnetic oxygen deficit were computed from in situ profiles; selective withdrawal patterns were computed based on temperature profiles and hourly project operation records. Results for the 1985 season indicated that the model could be used to provide a rapid and more accurate estimate of oxygen requirements than previously available. When compared with operation of the system based only on maintain...

The oxygen resources of the hypolimnion of ionically enriched onondaga lake, NY, U.S.A.

The depletion of hypolimnetic DO and the upper depth boundary of anoxia for four different years (1978, 1979, 1980 and 1981), and the accumulation of sulfide for a single year (1981), are documented for ionically enriched hypereutrophic Onondaga Lake, NY, USA. The depletion rate, represented as the areal hypolimnetic oxygen deficit (AHOD, g m−2 day−1), was extremely high (1.2–2.7 g m−2 day−1), The large differences in the rate within individual years and from year to year were largely a result of differences in attendant vertical mixing (parameterized as the hypolimnetic heating rate). The entire hypolimnion (depth interval from 11 to 20 m) was without O2 by late June of all 4 yr; anoxia was observed above the hypolimnion on some occasions when secondary stratification occurred. Sulfide accumulated progressively in the hypolimnion in 1981 following the onset of anoxia to a volume weighted concentration of I1 mg L−1. The ionic discharge from an adjoining alkali manufacturer exacerbated the problem of limited O2 resources of the hypolimnion by: (1) decreasing vertical mixing, (2) prolonging the duration of stratification, (3) causing abbreviated turnovers, and (4) encouraging increased rates of phytoplankton settling.

Nutrient internal cycling and the trophic regulation of Green Lake, Wisconsin1

Algal nutrients (Si, N, P) and dissolved oxygen were studied in Green Lake, Wisconsin, in 1971– 1972, and in 1978–1980 following a reduction of about 35% in total external P loading in December 1976.Despite oxic conditions, there is more P in the hypolimnion than would be expected from the dissolved oxygen and from classical Redfield stoichiometry. Because of a metalimnetic dissolved oxygen minimum in late summer, the calculation and interpretation of the hypolimnetic oxygen deficit is affected by turbulent transport of dissolved oxygen.Vertical fluxes of P into the mixed layer are important in late spring and early summer, but, owing to metalimnetic P depletion, negligible between mid‐July and mid‐October. Vertical transport of Si into the mixed layer is negligible in summer and early fall compared with inputs from the land drainage basin.Although P is high at spring turnover, epilimnetic concentrations of P are low and Secchi transparency is high by mid‐to‐late summer. These seasonal changes are caused by sedimentation of P and low seasonal inputs from the drainage basin. This P is recovered in the hypolimnion and recirculated throughout the lake at fall overturn. It causes silica limitation of the diatom bloom each succeeding spring.The total P content of Green Lake and its seasonal partition among the layers were remarkably stable between 1971 and spring 1980, despite the reduction in external loading in 1976. The hypolimnetic oxygen deficit also showed no significant change between the first and eighth decades of this century.

Dependence of Hypolimnetic Oxygen Consumption on Ambient Oxygen Concentration: Fact or Artifact?

Ten lakes studied in this investigation and the data presented by previous authors are all consistent with the hypothesis that rates of oxygen depletion in the hypolimnion of lakes do not depend upon the ambient oxygen concentration over the range of concentrations from 12 mg/L to 1.0 mg/L. By definition, aerobic respiration must stop when there is no more oxygen present. Therefore the hypolimnetic oxygen deficit can be modeled as a zero‐order chemical process that is independent of oxygen concentration. Predictions of seasonal changes in hypolimnetic oxygen concentrations can be made by estimating the slope of the linear regression of oxygen concentration against the Julian day when the sample was collected.

The physical limnology of Augher Lough (Northern Ireland)

SUMMARY. The physical limnology of Augher Lough, Northern Ireland (area=9.25 ha. z=5.5 m), including stratification pattern, heat budget, thermocline erosion rate, eddy diffusion rate in the thermocline and hypolimnion and areal hypolimnetic oxygen deficit is described. Oxygen and temperature profiles, recorded at two sites during 1978 and four sites during 1979, showed that spatial variability of these quantities was low and allowed the following lake characteristics to be estimated. Heat budgel was 5.30 kcal cm‐2 (standard deviation=s=0.26) in 1978 and 5.00 (s= 0.26) in 1979. The thermocline depth was 3.5–6.5 m with an erosion rate of 1.9X10‐7 m s‐1 in 1979. Eddy diffusion coefficients of heat in the thermocline and hypolimnion normally ranged from 0.48X 10‐2 cm2 s‐1 (s=0.20X10‐2) to 5.4X10‐2 (s=2.6X10‐2), but reached 10X10‐2 cm2s‐l (s=9X10‐2) in early July 1978 after a cooling‐mixing episode in the epilimnion. The hypolimnetic oxygen deficit was 680 mg O2 m‐2 d‐1 (s=76) and varied strongly with depth. A cooling‐mixing episode in the epilimnion in June‐July 1978 caused the movement of heat down to 8 m, movement of oxygen down to 6 m and increased the eddy diffusion coefficients of heat by an order of magnitude.

Hypolimnetic Metabolism in Three Cape Cod Lakes

The hypolimnetic oxygen deficits and carbon dioxide increments in three closed-basin, kettle lakes on Cape Cod were examined during summer stratification in 1976. Areal hypolimnetic 02 deficits ranged from oligotrophic (Gull and Hathaway Ponds) to distinctly mesotrophic (Mares Pond). Areal hypolimnetic dissolved inorganic carbon increments (assuming aerobic RQ = 0.85) ranged higher, to borderline eutrophic for Mares Pond. Both 02 uptake and dissolved inorganic carbon (DIC) release were correlated inversely with the amount of light reaching the hypolimnion. The observed ratios of DIC released to 02 taken up (respiratory quotient? RQ = C02/02) in the hypolimnia of the three lakes varied from 1.4 (Mares) to 3.4 (Gull), and appeared to correlate directly with the amount of light reaching the hypolimnion. Thus, underwater light appears to suppress 02 uptake more than DIC release. This raises the possibility that lakes significantly augment their inventories of alternate electron acceptors by donating electrons to anaerobic photosynthesis at or below the light compensation depth.

The areal hypolimnetic oxygen deficit: An empirical test of the model1

The areal hypolimnetic oxygen deficit (AHOD) model was tested by examining the relationship between rates of hypolimnetic oxygen depletion and three measures of lake trophic status. Measurements of AHOD were positively correlated with the measured total phosphorus concentration and with annual 14C pelagic primary production and inversely correlated with mean summer Secchi depth. Because each of the correlations between AHOD and trophic status explained <45% of the observed variation in A HOD values, other factors must also influence the AHOD of a lake. Significant amounts of the residual variation were explained by including the mean depth of the lake and mean hypolimnetic temperature as additional independent variables in a multiple regression analysis. A lake with a thicker or warmer hypolimnion had a higher AHOD than a lake with a shallow or colder hypolimnion. The AHOD model was developed to eliminate the influence o f lake morphometry on interlake comparisons of hypolimnetic oxygen depletion, but it does not do this and a new model must be developed.

The effect of sewage effluent on Grasmere (English Lake District) with particular reference to inorganic nitrogen transformations

SUMMARY. In the summer of 1971 the village of Grasmere was converted from septic tank to mains drainage with sewage treatment at an activated sludge plant. The effluent was discharged into the River Rothay, the main inflow of a nearby small lake (Grasmere). This paper describes some of the effects on the lake. The mean areal hypolimnetic oxygen deficit increased from 274 to 434 mg O2 m−2 day−1 with an accompanying marked increase in the degree of deoxygenation in the hypolimnion. Plate counts of bacteria in the surface water increased for 2 years but this increase was not sustained. The mean summer soluble reactive phosphorus concentration did, however, increase significantly (P= 0.05), but the same was not true of nitrate levels. This paper is particularly concerned with inorganic nitrogen transformations and analyses of the main inflow have shown that 50–98% of the ammonia and 10–40% of the nilrate entering in this river was derived from the sewage effluent. The concentrations in the main body of the lake were usually lower, possibly due to assimilation and denitrification in the shallower reaches of the lake. Seasonal changes in the inorganic nitrogen species in the hypolimnion showed three distinct phases of activity, ammonification, nitrification and denitrification. Nitrification accounted for approximately a quarter of the oxygen uptake in the hypolimnion.

Seasonal algal succession and cultural eutrophication in a north temperate lake

A year-round study of the algal composition of a previously uninvestigated north temperate, dimictic lake revealed the abundance of many pollution-tolerant forms, including such toxin-producing blue-greens as Anabaena and Aphanizomenon. A significant hypolimnetic oxygen deficit (0.4 ppm, 3.5% saturation) in late summer and the rate of oxygen depletion from 1 August to 19 September (0.13 mg/ml/day) further indicate eutrophic conditions. Of the three groups considered in this study (Chlorophyta, Bacillariophyta and Cyanophyta), the Cyanophyta were less diverse in terms of relative numbers of genera but produced the largest blooms. Chlorophyta had the greatest number of genera. Diatoms dominated in winter and spring, Chlorophyta in summer and fall and blue-greens in late summer, fall and winter. Spirogyra and Oscillatoria were the most ubiquitous members of the algal flora. Important perennials included Oscillatoria, Spirogyra, Closterium, Fragilaria, Meridion, Tabellaria and Cymbella. No unialgal blooms ever occurred. The accelerated rate of eutrophication in recent years is due primarily to excess nutrient loading resulting from input of raw domestic sewage. The completion of a sanitary sewer system is expected to alleviate the excessive nutrient loading and thereby slow the eutrophication process.

Development of oxygen deficits in 14 southern Ontario lakes1

Areal hypolimnetic oxygen deficits in 14 southern Ontario lakes developed linearly throughout summer in 13 of the lakes and decreased, usually linearly, as the upper limit of the hypolimnion was chosen at successively greater depths. Areal hypolimnetic oxygen deficit ranged from 0.006 to 0.041 mg cm−2 day−1; it was not correlated with average dry weight of seston in summer but was correlated with average Secchi depth during summer.

Limnological Conditions in Five Small Oligotrophic Lakes in Terra Nova National Park, Newfoundland

Five oligotrophic lakes in Terra Nova National Park, Newfoundland, varying in mean depth (1.06–9.22 m), in water renewal rate (0.2–20.7 times per annum), in salinity (18.2–42.6 mg/liter), in total phosphorus (0.1–0.6 mg-at P/m3), and in chlorophyll a concentration (0.5–3.2 mg/m3), were investigated for 17 mo in 1969 and 1970. Hypolimnetic oxygen deficits ranged between 111 and 217 mg O2 per m2/day. Low levels of nutrients, reduced solar radiation, and low underwater light penetration, owing to excessive cloudiness and high water color, seriously limited planktonic primary production. The relation between primary production at optimum light, and water renewal per annum, appeared to be curvilinear when the rate of primary production began to decline above an optimum water renewal rate. The seasonal and annual variations in water color and salinity were dependent on the rate of water renewal, but other lakes on the catchment areas modified that relation. Winter road salting operations within the catchment area caused a considerable increase in salinity, total phosphorus concentration, and primary production in one lake. A new morphometric index which reflects the littoral effect on basin volume was proposed.