Denton, G.H., J.G. Bockheim, S.C. Wilson, and M. Stuiver. 1989. LateWisconsin and early Holocene glacial history, inner Ross embay-ment, Antarctica. Quaternary Research, 31(2), 151-182.

Doran, P.T., R.A. Wharton, Jr., and W.B. Lyons. 1994. Paleolimnologyof the McMurdo Dry Valleys, Antarctica. Journal ofPaleolimnology, 10(2),85-114.

Green, W.J., M. Angle, and K. Chave. 1988. The geochemistry ofantarctic streams and their role in the evolution of four lakes inthe McMurdo Dry Valleys. Geochimica et Cosmochimica Acta,52(5), 1265-1274.

Lawrence, M.J.F., and C.H. Hendy. 1989. Carbonate deposition andthe Ross Sea ice advance, Fryxell basin, Taylor Valley, Antarctica.New Zealand Journal of Geology and Geophysics, 32(2),267-277.

Nesje, A. 1992. A piston corer for lacustrine and marine sediments.Arctic and Alpine Research, 24(3), 257-259.

Rau, G., T. Takahashi, and D. Des Marais. 1989. 13 C depletion inantarctic marine plankton: Parallels to past oceans? Nature,341(6242), 516-518.

Stuiver, M., G.H. Denton, T.J. Hughes, and J.L. Fastook. 1981. His-tory of the marine ice sheet in West Antarctica during the lastglaciation, a working hypothesis. In G.H. Denton and T.H.Hughes (Eds.), The last great ice sheets. New York: Wiley-Inter-science.

Wharton, R.A., Jr., W.B. Lyons, and D.J. Des Marais. 1993. Stable iso-topic biogeochemistry of carbon and nitrogen in a perennially ice-covered antarctic lake. Chemical Geology, 107, 159-172.

McMurdo LTER: Inorganic geochemical studies with specialreference to calcium carbonate dynamics

K. WELCH and W.B. LYONS, Department of Geology, University ofAlabama, Tuscaloosa, Alabama 35487-0338J.C. PRISCU and R. EDWARDS, Department of Biology, Montana State University, Bozeman, Montana 59712

D.M. MCKNIGHT and H. HOUSE, Water Resources Division, U.S. Geological Survey, Boulder, Colorado 80303R.A. WHARTON, JR., Biological Sciences Center, Desert Research Institute, Reno, Nevada 89506

During the first field season (1993-1994) of the McMurdoDry Valleys Long-Term Ecological Research (LTER) pro-

gram, we collected, processed, and analyzed samples for geo-chemical and biogeochemical analysis. The following analy-ses were conducted on the majority of these samples: pH, dis-solved inorganic carbon (CO2), sodium (Na), potassium(K), magnesium (Mg2 -), calcium (Ca2 ), chloride (Cl-), sulfate(SO421, nitrate (NO3-), nitrite (NO2j, ammonium (NH4),phosphate (PO4 3-), dissolved organic carbon (DOC), and sta-ble isotope ratios (8 180 and ÔD) of the water.

Each of the three major lakes in Taylor Valley (Bonney,Fryxell, and Hoare) were sampled at least three times duringthe field season. Lakes were systematically sampled at regulardepths, and biological as well as chemical samples wereobtained (Priscu, Antarctic Journal, in this issue). Althoughprevious work on the geochemistry of these lakes has beenpublished since the early 1960s, little comparison work hasbeen undertaken. Chloride profiles from the third "limnorun" of the season (21 December 1993, 23 December 1993, 29December 1993, and 7 January 1994) are shown for both theeast and west lobes of Lake Bonney as well as Lakes Fryxelland Hoare in figure 1. This comparative approach emphasizesthe radically different chemical compositions of lakes, withLake Hoare being the freshest and Lake Bonney (both lobes)being the most saline. One of the most intriguing questionsabout the McMurdo Dry Valleys is, how did these lakes,essentially evolving in a similar climatic region, draining simi-lar geologic materials, evolve into such different lakechemistries?

Figure 2 is a plot of the Ca:Cl ratios in the lakes. Includedin this figure are data for Lake Vanda in Wright Valley fromGreen and Canfield (1984). The Ca 2 profiles are "normalized"to Cl-to eliminate any variation due to changes in total dis-

LTER LIMNO RUN 3

CI (meq/L)

1101001000io

10

20a)

Ii

40

Figure 1. Depth profile of Cl- in Lake Bonney, Lake Hoare, and LakeFryxell.

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237

Ca/Cl (mM)

0.0010.010.11 10El

10

20

50

60

70Figure 2. Depth profile of the Ca2 to Cl- ratios in the lakes.

solved solids alone. The Ca:Cl profiles from Lakes Hoare andVanda are essentially constant with depth, whereas Ca2depletion, relative to Cl-, occurs for both lobes of Lake Bon-ney and Lake Fryxell (figure 2).

The table summarizes the Ca:Cl and Ca:HCO 3 ratios forsnow, other southern Victoria Land streams, and some of our(i.e., LTER) recent data from streams contributing to LakeHoare. When all the information is combined, a set of phe-nomena becomes apparent. Precipitation in regions wherelittle to no ice-free area exists has Ca:C1 approximately twiceas great as the sea water ratio, whereas, even in areas of highelevation above the valley floors, the ratio for precipitation isapproximately 6 to 10 times greater than that of sea water(table). This indicates that in the ice-free areas in Antarctica, anonmarine, terrestrial dust or salt source of Ca2 relative toCl- exists (e.g., Welch et al., in preparation). As the glaciersmelt and become stream discharge, however, the Ca:Cl ratioincreases to very high values (table), with the shorter streams(i.e., the Lake Hoare streams) having the highest Ca:Cl ratios.These data indicate that calcium minerals, undoubtedly calci-um carbonate (CaCO 3), are rapidly being dissolved from soilsas liquid water becomes available in the austral summer.Because the regolith in the McMurdo Dry Valleys has abun-dant CaCO3 present (Keys and Williams 1981), this is certainlynot a surprising observation.

After the streams enter the lakes, the ratios change dra-matically again, as the Ca:Cl is greatly decreased. Note thatthe surface value of Lake Fryxell does look much like a streamvalue. On the other hand, the surface values are an order ofmagnitude less than the streams, suggesting rapid Ca2removal. The precipitation of carbonate minerals in antarcticlacustrine environments has been reported by several authors

(Wharton, Parker, and Simmons 1983;IT 1 1OQO. i__

Stream and precipitation data from the McMurdo Dry Valleys (molar ratios) aIuiiIiILLY 1.JU

and Chave inii; tsira et al. ini). meinteraction and interplay between thedynamics of CaCO3 formation and disso-lution and the production and oxidation

4.4 of organic carbon are undoubtedly-Welch et al. (in preparation) responsible for the dramatic differencesWelch et al. (in preparation)

I observed in the Ca2 and HCO3- chemis-0.40Green and Canfield (1984) tries in the dry valley lakes, with the over-0.29DeMora, Whitehead, and Gregory (1991)printing of biological processes on the

Lyons and Welch (unpublished data)r,diit.tin nnd d p triii'tinn nf C(iL.S.,--varying from lake to lake. This is the case0.45because the rates of biological processes0.45vary from lake to lake. For example, the1.0pelagic primary production maxima inthese lakes differs by at least one order ofmagnitude in midsummer, with LakeFryxell and the west lobe of Lake Bonneyhaving the highest rates (Vincent 1988;Priscu and Edwards unpublished data).This biological influence is reflected notjust in the variations in ICO2, but also inthe 813C composition of the XCO2 as well(Wharton et al. 1993). In addition, rela-

ANTARCTIC JOURNAL - REVIEW 1994238

Sea water 0.019Snow (non dry valley) 0.04-0.08Snow (dry valley area) 0.12-0.25Onxy River0.56AIph River 0.88Streams Entering Lake HoareSimmons

9 December 1991 1.310 January19940.5926 January19941.2

Vestal2 December 1993

11 January199426 January1994

Wharton2 December 1993

11 January1994McKay

2 December 199311 January1994

1.40.53

1.40.61

3.50.51

2.00.49

4.10.48

3.00.51

3.40.54

tively high rates of sulfate reduction and methane productionoccur close to the sediment-water interface in Lake Fryxell(Howes and Smith 1990). All these data indicate that LakeFryxell, and perhaps the west lobe of Lake Bonney, will haveCaCO3 dynamics dominated by biological activity, whereasthe other two lakes, especially Lake Hoare, may not. Our aimis, in part, to compare and contrast the affects of high biologi-cal vs. low biological activities on the dynamics (i.e., produc-tion and dissolution) of CaCO3 in these lake systems.

This research was supported by National Science Foun-dation grant OPP 92-11773. Special thanks are given to L.Mastro, A. Butt, G. Dana, and P. Doran for help with samplecollection.

References

Bird, M.I., A.R. Chivas, C.J. Randell, and H.R. Burton. 1991. Sedimen-tological and stable-isotope evolution of lakes in the Vestfold Hills,Antarctica. Palaeogeography, Palaeoclimatology, and Palaeoecolo-gy, 84, 109-130.

DeMora, S.J., R.F. Whitehead, and M. Gregory. 1991. Aqueous geo-chemistry of major constituents in the Mph River and its tributariesin Walcott Bay, Victoria Land, Antarctica. Antarctic Science, 3, 73-86.

Green, W.J., M.P. Angle, and K.E. Chave. 1988. The geochemistry ofantarctic streams and their role in the evolution of four lakes in

the McMurdo Dry Valleys. Geochimica et Cosmochimica Acta, 52,1265-1274.

Green, W.J., and D.E. Canfield. 1984. Geochemistry of the Onyx Riverand its role in the chemical evolution of Lake Vanda. Geochimicaet CosmochimicaActa, 48, 2457-2467.

Howes, B.L., and R.L. Smith. 1990. Sulfur cycling in a permanentlyice-covered amictic antarctic lake, Lake Fryxell. Antarctic Journalof the U.S., 25(5), 230-232.

Keys, J.R., and K. Williams. 1981. Origin of crystalline, cold desert saltsin the McMurdo region, Antarctica. Geochimica et CosmochimicaActa, 45, 2299-2309.

Lawrence, M.J.F., and C.H. Hendy. 1989. Carbonate deposition andRoss Sea ice advance, Fryxell Basin, Taylor Valley, Antarctica. NewZealand Journal of Geology and Geophysics, 32, 267-277.

Priscu, J.C. 1994. McMurdo LTER: Phytoplankton nutrient deficiencyin lakes of the Taylor Valley, Antarctica. Antarctic Journal of theU.S., 29(5).

Vincent, W.F. 1988. Microbial ecosystems of Antarctica. Cambridge:Cambridge University Press.

Welch, K.A., P.A. Mayewski, J.E. Dibb, M.S. Twickler, and S.I. Whitlow.In preparation. Marine and polar continental air mass influence inglaciochemical records from the Dry Valley region of Antarctica.Atmospheric Environment.

Wharton, R.A., Jr., W.B. Lyons, and D.J. Des Marais. 1993. Stable iso-tope biogeochemistry of carbon and nitrogen in a perennially ice-covered antarctic lake. Chemical Geology, 107, 159-172.

Wharton, R.A., Jr., B.C. Parker, and G.M. Simmons, Jr. 1983. Distribu-tion, species composition and morphology of algal mats in antarc-tic dry valley lakes. Phycologia, 22, 355-365.

McMurdo LTER: Phytoplankton nutrient deficiency in lakes ofthe Taylor Valley, Antarctica

JOHN C. PRISCu, Department of Biology, Montana State University, Bozeman, Montana 59717

previous reports on nutrient deficiencies in antarctic lakeshave been based on indirect evidence such as nitrogen-

to-phosphorus ratios in the water column (Vincent 1981;Priscu et al. 1989), nutrient ratios in streams entering thelakes (Canfield and Green 1985), and direct measurement ofnitrogen uptake using nitrogen-15 labeled compounds(Priscu 1989, pp. 173-182; Priscu et al. 1989). With the incep-tion of studies focusing on photosynthesis (Priscu et al. 1990),nitrogen transformations (e.g., Priscu, Ward, and Downes1993), and long-term ecological research (Wharton, AntarcticJournal, in this issue) in the lakes of the dry valley region ofMcMurdo Sound, knowledge of nutrient regulation of prima-ry productivity in these systems is imperative. This article pre-sents results from experimental nutrient (nitrogen and phos-phorus) bioassays conducted on Lakes Bonney (east and westlobes), Hoare, Fryxell, and Vanda.

Experiments were conducted on phytoplankton popula-tions at 5, 13, and 18 meters and 5 and 13 meters in the eastand west lobes of Lake Bonney, respectively, and at 5 meters inLakes Hoare, Fryxell, and Vanda. The depths selected for LakeBonney were from phytoplankton biomass and productivitymaxima; those for the other lakes represent the phytoplankton

populations immediately beneath the permanent ice covers.All experiments were conducted at the Lake Bonney fieldcamp during November and December 1993. A 4-liter samplewas enriched with carbon-14 bicarbonate (0.1 to 0.2microcuries per milliliter (mL) final concentration), and 500mL was decanted into each of eight acid-washed high-densitypolyethylene bottles. Two bottles each were then enrichedwith 20 micromolar (!IM) ammonium, 2 tM phosphorus, and20 iM ammonium plus 2 tM phosphorus; 2 nonamended bot-tles served as controls. All bottles were placed in an environ-mental chamber that simulated light and temperature condi-tions from which the samples were collected. Subsamples (80mL) were removed from each bottle at 24-hour intervals (for144 hours) and filtered through Whatman GF/F filters. The fil-ters were acidified with 0.5 mL of 3 normal hydrochloric acidand dried at 50°C to remove unincorporated isotope. Radioac-tivity on the filters (which represents photosynthetic activity)was determined by standard liquid scintillation spectrometryat McMurdo Station. Nutrient chemistry was measured usingmethods described by Sharp and Priscu (1990).

Photosynthesis in all phytoplankton populations sampledfrom Lake Bonney was stimulated strongly, relative to the non-

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