algae and their aquatic neighbors so that reasonable interpretations of the role played by carbon can be made and to present some of the evidence that organic carbon, biodegradable organic pollution, plays an important role in determining whether or not massive algal blooms grow under some rather common circumstances.

"We see no reason to alter our views that the increase in concentration of phosphates in river water used for water supply, which can be attributed to domestic detergents, has not caused any increased difficulties in operating storage reservoirs prone to algal growths, the concentration of phosphates in most natural surface waters of the United Kingdom being higher than the critical concentration which is required to support growth of algae. We do not consider that there has been shown to be a need to replace the phosphates incorporated in synthetic detergent formulations by alternative materials, such as NTA . . .".

In concluding, I should like to summarize:

1. Blue-green algae and certain bacteria are always found together in natural waters. Each supplies the other with major nutrient requirements of carbon dioxide and oxygen.

2. Blue-green algae require major amounts of carbon dioxide to grow. It takes two pounds of carbon dioxide to produce one pound of algae, dry weight.

3. Sufficient carbon dioxide at suitable rates can not be delivered by inorganic sources of the atmosphere and bicarbonate salts to support rapid massive algal bloom development.

4. Bacteria supplied with nominal amounts of organic matter can deliver massive amounts of carbon dioxide to growing algae without problems of diffusion and interface transfer rates.

5. Massive algal blooms are nearly always associated with excessive organic pollution and explosive algal growth is always accompanied by explosive growth of bacteria.

6. Phosphorus is required in very small amounts. Waters containing 10 parts per billion have supported massive algal blooms in the presence of excessive organic pollution.

7. Algae have the capacities to (a) store excessive amounts of phosphorus for use in rapid growth periods, and (b) release much of the phosphorus when growth stops so that it can be used by younger cells. Thus, the same phosphorus may be used several times in a single growing season.

8. The very small amounts of phosphorus required to support massive algal bloom development are already present in most natural waters in this country. Elimination of phosphates from detergents will not alter this situation because of the steadily increasing amounts coming from a wide variety of other sources.

9. Control of algal bloom nuisances by reductions of phosphorus in effluents to natural waters will be very difficult. To my knowledge, there has been no situation reported where control of phosphorus has resulted in control of algal blooms in the presence of organic pollution. Numerous failures are on record.

10. Numerous examples, both large scale and small, have been reported where control of algal growth has been achieved by control of organic pollution, even in the presence of excessive amounts of phosphorus.

Finally, these findings suggest that more attention should be given to control of BOD in this country. An 80% removal by a given sewage treatment plant means 20 mg/1 BOD in its effluent only if the incoming sewage measures 100 mg/1 BOD. Such influent may be many times higher than 100. In Britain, the effluent must contain no more than 20 mg/1 BOD regardless of the BOD content of the incoming stream. This is much more effective. It would seem that the current furor over phosphate removal could be better directed at BOD removal. This would result in great savings of money and a more positive control of the algal bloom problem.

[Presented to the Environmental Science Division of the New York Academy of SciencesFeb. 3, 1971]

"PHOSPHORUS VS. CARBON AS A FACTOR IN ALGAE BLOOMS AND
DETERIORATION OF WATER QUALITY"

(By L. E. Kuentzel)

ABSTRACT

Considerable emphasis is currently being placed on phosphorus as a major cause of pollution in lakes by stimulating massive growths of algae. Recent

literature surveys and field and laboratory work indicate that, while small amounts of phosphorus are required, the major nutrient is carbon dioxide which can only be supplied in massive amounts for algal growth by the action of bacteria on excessive organic pollution. The amounts of CO available from the atmosphere and alkalinity are limited by rates of solution, diffusion and by pH while that generated by bacterial action in proximity to the algae is dependent only on the logarithmic growth rate of bacteria and the degree of organic pollution. Massive increases in the numbers of bacteria always accompany massive algal blooms. Finally, the peculiar abilities of algae to store, use and reuse phosphorus make possible massive growths on far less than stoichiometric amounts in waters that contain little or no phosphorus, so long as ample CO2 is available. Yet, in laboratory and field studies, it is apparent that control of the biological source of CO2 has limited algal growth in the presence of greatly excessive amounts of phosphorus. This suggests that biological oxygen demand (BOD) is a major factor in causing massive algal blooms and should be included in programs designed to control such growths.

[Water pollution control research series 16050 FGS 07/70]

THE INTERRELATION OF Carbon and PHOSPHOROUS IN REGULATING HETEROTROPHIC AND AUTOTHROPIC POPULATIONS IN AQUATIC ECOSYSTEMS

(By Pat C. Kerr, Doris F. Paris, and D. L. Brockway)

ABSTRACT

Laboratory and field investigations were conducted on the fate and cycling of carbon and phosphorus in selected aquatic ecosystems. Inorganic carbon, as CO2, supplied by both bacterial cultures and cylinder gases, stimulated the growth of the blue-green alga Anacystis nidulans. The carbon requirement (10 ug CO2 per cell) for this alga was determined for a single set of experimental conditions. The addition of CO, to natural water low in phosphorus (5 ug P) and nitrogen (5 ug N) in the laboratory stimulated the growth of indigenous algal populations. The limiting and luxury cellular concentrations of phosphorus for starved Anacystis nidulans were found to be 0.3 × 10 ug P and 3.0 × 10 ug P per cell, respectively.

Diel studies of a stream which received biological-treated sewage demonstrated that the dissolved CO2 and HCO3 continually produced in the system were essentially depleted by the autotrophic organisms during daylight hours, while the concentration of phosphorus (1.3-2.2 mg/1 P) remained unchanged. Addition of organic carbon and inorganic nitrogen and phosphorus alone and in combination to the waters studied directly stimulated the oxidative metabolism of the heterotrophic population, which resulted in increased dissolved CO; and HCO3. This increased availability of inorganic carbon, rather than the direct metabolic removal of dissolved phosphorus by the algae, appeared to be directly responsible for the growth of the algal populations in the waters studied.

BIOLOGICAL RESPONSES FOLLOWING NUTRIENT ADDITIONS TO A SMALL POND* (By D. L. Brockway, Doris F. Paris, Pat C. Kerr, and J. T. Barnett, Jr.**)

ABSTRACT

Within twelve hours after reagent-grade nitrogen, phosphorus, and potassium chloride were added to a small Georgia fishpond, the bacterial population increased. The algal population increased 36-48 hours after fertilization. Diel cycling of CO2 and HCO was measured. Although the data do not clearly indicate that increased availability of inorganic carbon was responsible for initiation of algal growth, continued biological production of CO2 appeared to prolong

*For presentation by the senior author at the 26th Purdue Industrial Waste Conference, Purdue University, Lafayette, Ind., May 4, 1971, and for publication in the proceedings. **Environmental Protection Agency, Water Quality Office, Southeast Water Laboratory. National Pollutants Fate Research Program, College Station Road, Athens, Ga. 30601.

the duration of the bloom. Data indicate more nitrogen and phosphorus were removed during night than during day; the higher removal was associated with removal of O2, decreasing pH, and CO and HCO, accumulation in the water, indicating heterotrophic activity. CO2 was removed and HCO was depleted from the water during hours of light.

Algal growth was stimulated by bubbling 5% and 0.03% CO2 in air through water in two plastic enclosures in Shriner's Pond. These field experiments indicate the importance of carbon in regulating algal growth.

[Copyright as part of the December 1970, JOURNAL WATER POLLUTION CONTROL FEDERATION, Washington, D.C. 20016]

THE ROLE OF CARBON IN EUTROPHICATION

(By Darrell L King, Associate Professor of Civil Engineering, University of Missouri, Columbia)

Lake eutrophication is a term that has been defined, redefined, and used in many different contexts by many authors to explain the enrichment of waters. In general, all those applying this term have used it in conjunction with increases in plant production within lakes as a function of time. Most authors generally agree that this increased plant productivity is associated directly with increased nutrient concentration in the lake. To some, eutrophication is caused by increases in nitrogen and phosphorus content of lakes, while others associate eutrophication with the addition of organic matter to lakes. However, all seem to agree that increased human activity in a lake basin tends to accelerate eutrophication. A lake generally is considered to be eutrophic when it supports summer blooms of blue-green algae and shows oxygen depletion in the hypolimnion.

The roles of nitrogen, phosphorus, and other macronutrients, as well as many of the micronutrients in the enrichment process have been discussed and summarized (1) (2) (3) (4) (5) (6), but little attenton has been given to the significance of the amount of carbon available for algal photosynthesis. In fact, it is widely believed that because carbon dioxide is available from the atmosphere, carbonate alkalinity, and respiratory activity, it will never be limiting in natural waters (7).

Much of the current theory used to explain fertility of natural waters is simply an extension of the models used to manage terrestrial agriculture plant production. Such direct comparison ignores basic differences in carbon availability in the terrestrial and aquatic regimes. Carbon dioxide is available to terrestrial plants from the atmosphere at a low concentration, but wind movement maintains this concentration at a nearly constant level. Aquatic plants, separated from the atmosphere by a foot or more of water, do not have access to atmospheric carbon dioxide except under conditions of extreme wind movement. In fact, exchange of carbon dioxide between water and the atmosphere seems to be a very slow process (8).

During the period from 1910 to 1938, several papers (9) (10) (11) (12) (13) were published indicating that available carbon dioxide is the factor limiting algal photosynthesis in nutrient-enriched laboratory waters. In 1911, Birge and Juday (14) suggested that free carbon dioxide and available bicarbonate were the factors most likely limiting algal production in natural waters. Burr (15) noted that aquatic plants seem to have adapted to low light intensities but not to low carbon dioxide concentrations. More recently, Bartsch and Allum (16) suggested that carbon is probably the limiting nutrient in wastewater lagoons, and Wright (17) and Wright and Mills (18) noted carbon limitations on photosynthetic activity in both Canyon Ferry Reservoir and the Madison River. The low algal productivity characteristic of acid strip-mine lakes also seems to be related to a lack of an available photosynthetic carbon source. In this case, mineral acidity maintains the equilibrium at a point well below the pK1 for carbonic acid. With no bicarbonate reserve, the algae are limited to free carbon dioxide at atmospheric equilibrium, an amount of carbon dioxide sufficient to allow only limited algal production.

Although nitrogen, phosphorous, and a variety of other nutrients are required by algae, eutrophication seems to be ultimately a carbon-accumulation phenomenon. Initial algal response to additions of nitrogen and phosphorus to an oligotrophic lake indicates that one of these basic nutrients is the factor limiting

photosynthesis in that lake. However, in a lake with low alkalinity, biological indicators of eutrophication, such as midsummer blue-green algal blooms, often are noted following only slight additions of nitrogen and phosphorus. Because blue-green algae can function at lower equilibrium carbon dioxide levels than most other algae, less nitrogen and phosphorus would be required to establish blue-green algal dominance in lakes with low alkalinity. The amount of nitrogen, phosphorus, and other plant nutrients required to produce midsummer blue-green algal dominance in any lake seems to be related directly to the bicarbonatecarbonate alkalinity of that lake.

Any attempt to maximize algal productivity while maintaining algal species suitable for human or animal food will require control of carbon dioxide availability in addition to the supply of sufficient quantities of other plant nutrients to allow unhindered algal photosynthesis. The scarcity of carbon dioxide in water precludes the unilateral application of terrestrial agricultural theories and practices to aquatic systems.

ACKNOWLEDGMENTS

These studies were financed by the Missouri Water Pollution Board, the Engineering Experiment Station of the University of Missouri-Columbia, and FWPCA Training Grant 5T1-WP-30.

REFERENCES

1. Sawyer, C. N., "Fertilization of Lakes by Agricultural and Urban Drainage." Jour. New England Water Works Assn., 61, 109 (1947).

2. Weiss, C. M., "Relation of Phosphates to Eutrophication." Jour. Amer. Water Works Assn., 61, 387 (1969).

3. Gerloff, G. C., and Skoog, F., "Nitrogen as a Limiting Factor for the Growth of Microcystis aeruginosa in Southern Wisconsin Lakes." Ecology, 38, 556 (1957). 4. Fruh, E. G., "The Overall Picture of Eutrophication." Jour. Water Poll. Control Fed., 39, 1449 (1967).

5. Provasoli, L., "Micro-Nutrients and Heterotrophy as Possible Factors in Bloom Production in Natural Waters." In "Algae and Metropolitan Wastes." R. A. Taft San. Eng. Center, Cincinnati, Ohio, TR W61-3 (1961).

6. Goldman, C. R., "Micronutrient Limiting Factors and Their Detection in Natural Phytoplankton Populations." In "Primary Productivity in Aquatic Environments." Mem. Ist. Ital. Idrobiol., 18 Suppl., Univ. of California Press, Berkeley (1965).

7. Nesbit, J. B., "Phosphorus Removal-the State of the Art." Jour. Water Poll. Control Fed., 41, 701 (1969).

8. Harvey, H. W., "The Chemistry and Fertility of Sea Water." 2nd Ed., Cambridge Univ. Press, Cambridge, Eng. (1957).

9. Nathansohn, A., "The Metabolism of Plants." Quelle and Meyer, Leipzig, Germany (1910).

10. Warburg, O., "Uber die Geschwindigkeit de photochemischen Kohlensaurezer-setzung in lebenden Zelen." Biochem. Zeits, 100, 230 (1919).

11. Osterhout, W. J. V., and Doreas, M. J., "The Penetration of CO2 into Living Protoplasm." Jour. Gen. Physiol., 9, 255 (1925).

12. Osterhout, W. J. V., and Hans, A. R. C., "On the Dynamics of Photosynthesis." Jour. Gen. Physiol., 1, 1 (1918).

13. Emerson, R., and Green, L., "Effect of Hydrogen-Ion Concentration on

FMC CORP.,

INORGANIC CHEMICALS DIVISION, Princeton, N.J., November 9, 1970. Re hearings on phosphate standards for Lake Michigan, November 4, 1970. Mr. RICHARD J. KISSEL,

Hearing Officer and Member, Illinois Pollution Control Board,
Chicago, Ill.

DEAR MR. KISSEL: At the subject hearings on November 4, 1970, I presented testimony in behalf of FMC Corporation. During the question-and-answer period I introduced a color photograph of laboratory experiments showing that bacteriaproduced carbon dioxide made algae grow about fifty times faster than normal. The "normal" conditions are essentially those specified in the Provisional Algal Assay Procedure issued February 1969 by the Joint Industry-Government Task Force on Eutrophication. The normal source of carbon dioxide is from the air

and from the sodium bicarbonate added as part of the nutrient mixture. This 50fold greater growth of algae occurred even though the amount of phosphate in all the flasks was identical.

As promised at the hearing, enclosed is the description of the experiment and results which should accompany the photographic exhibit.

I respectfully request that this letter and the attachment be entered into the record with the photograph exhibit.

Respectfully yours,

Enclosure.

PAUL F. DERR,

Assistant Director R. & D. Department.

FMC CORPORATION

The green alga Selenastrum capricornutum is seen growing is Gorham's medium. This is a nutrient-rich medium containing all nutrients essential for algal growth, inclusive of 7 mg/1 of phosphorus. The algae were grown under identical conditions of lighting, temperature and agitation according to the recommendations of the U.S. Government/Industry Joint Task Force on Eutrophication. Each of the flasks was inoculated with 1,000 cells/ml.

In the control flasks to the right, air exchange with the atmosphere is provided by means of foam stoppers. The second group of controls has air-tight Teflon stopcocks. To the left are three triple flasks, each representing a sealed but interconnected unit with bacteria in the center and identical algal flasks on