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ELSEVIER The Scienceof the Total Environment 206 (1997) l-15

A contribution to the study of the heavy-metal andnutritional element status of some lakes in the southern

Andes of Patagonia (Argentina)

B. Markert aT*,F. Pedrozob, W. Geller”, K. Friese”, S. Korhammer”,G. Bafficob, M. Diazb, S. W61fl”

‘Internatio nal Graduate Sch ool Zittau (IHI), Markt 23, 02763 Zittay Germany

bCentro Regional Universitario Bariloche, Universidad National de1 Comahue, Quintrall250,8400 Bariloche, Argentina

‘UFZ Centre for Environm ental Researc h Leipzig/ Halle , Department for Inland Water Resea rch Magdeburg,

Am Biedetitzer Busch 12,39114 Magdeburg, Germany

Received 17 March 1997;accepted20 June 1997

Abstract

Various nutrients and chemical elements, as well as other parameters, were to be measured by different methods

in water and plankton samples from three Argentinian lakes in the Andes: Lake Nahuel Huapi, Lake Gutierrez and

Lake Mascardi. The quality of the instrumental measurements was control led by independent methods (TXRF andICP/MS) and by using reference materials (NIST 1643~ and BCR/CRM 414). Al l the chemical concentrations werevery low, which means that al l the lakes can be classified as oligotrophic to ultra-oligotrophic. Slightly increased

concentrations within the lakes investigated may be attributed to anthropogenic influences from the town ofBariloche in the case of Lake Nahuel Huapi or to the glac ial influence of the Upper Manso River, which carriesconsiderable amounts of dissolved salts and suspended particles from the Tronador glacier. The waters are very

dilu te solutions dominated by calcium, bicarbonates and dissolved silica. The ionic composition is largely below theworld average given by Livingstone (1963, in: Home AJ, Goldman CR. Limnology, 2nd ed. USA: McGraw Hil l,

1994576). The Andean-Patagonian lake waters showed concentrations of Cr, Sr, Zn, Cu, Co and Pb that were of thesame order as the freshwater world average. The remaining elements (P, S, Si, Fe, Mn, Ni, Na, K, Mg, Ca, As, Cl andCd) fal l below or around the limit for the freshwater world average. With the exception of calcium, which is twice as

high as in reference freshwater (Markert B. Inorganic chemical fingerprinting of the environment; reference

freshwater, a useful tool for comparison and harmonization of analytical data in freshwater chemistry. Fresenius’ ZAnal Chem 1994;349:697-702), the element concentrations (S, Fe, Mg, Na, K and Sr) are lower than in referencefreshwater. The phytoplankton biomass was mainly dominated by Dinophyceae in Mascardi and Gutierrez lakes and

by Bacillariophyceae in Lake Nahuel Huapi. The phytoplankton shows greater accumulation of the minerals K andCa, and the essential trace elements (Mg, Fe, Cu and Zn) than the zooplankton. Sulphur occurs in greater

* Corresponding author.

0048-9697/97/$17.00 0 1997Elsevier ScienceB.V. Ail rights reserved.PZZ SOO48-9697(97)00218-O



2 B. Markert et al. / The Sci ence of the Tot al Environment 206 (1997) l-15

concentrations in zooplankton than in phytoplankton, this could be due to higher protein contents. In the case 01non-essential elements that are toxic at higher concentrations (As and Pb) it is noticeable that the levels are similar

for phyto- and zooplankton. This indicates that these substances are taken up passively from the water and deposited

in the organism. In general i t can be said that the organisms accumulate al l the elements by lOO- to lOOO-fold inrelation of the surrounding environment. 0 1997 Elsevier Science B.V.

Keywords: Lakes; Multi-element analysis; Heavy metals; Water; Plankton

1. Introduction

When evaluating the productivity and trophic

status of lakes it is essential to know of anyfactors that may limit the growth of phytoplank-

ton and zooplankton. The notion that most lakes

in the temperate zones are P-limited may indeedbe regarded as a paradigm of limnology (Zaucke

et al., 1992). This applies initially at the concep-

tual level o f a classic ecosystem approach that is

based on the abstract stage of the primary pro-

ducers. But in reality phytoplankton communities

are a complex mixture of species with highlyindividual life histories; this also applies to their

nutritional requirements. In view of their biologi-cal diversity it is most unlikely that all phyto-

plankton populations in a community of organ-

isms are limited by a single factor (Zaucke et al.,

1992; Markert and Geller, 1994). This is alreadyevident from the biochemical and metabolic fact

that plant organisms require a considerable num-

ber of other macronutrients (C, H, 0, N, P, S, K,

Ca and Mg) and micronutrients (Cl, Si, Mn, Na,

Fe, Zn, B, Cu, Cr, MO and Co) in order to exist.

Tropical water systems seem to differ fromthose of the temperate zones in that they have a

greater variety of factors limiting the growth of

algae (Zaucke et al., 1992). For example, evidence

of P-limitation emerges from bioassays of black-

water systems in the Amazon region (Zaret et al.,

1981) and various man-made lakes in Zimbabwe(Robarts and Southall, 1977). On the other hand,similar experiments conducted on tropical lakes

tend to indicate N-limitation; such water bodies

include various man-made lakes in Brazil (Henryand Tundisi, 19821, Lake Titicaca (Wurtsbauch et

al., 1985) and whitewater systems of the Amazon

region (Zaret et al., 1981; Grobelaar, 1983).

The following sections are devoted to the initial

results of a sampling campaign carried out on

Argentinean lakes in the Andes; this campaign

was intended as a pilot project for further investi-gations. As part of the work described, sampleswere taken from three different lakes to give a

rough idea of:

1. The nutrient and heavy-metal content of the

water; and

2. The composition of the phytoplankton andzooplankton.

The objective of this and subsequent series of

tests is to use such unpolluted lake systems as‘reference’ or ‘baseline’ systems for comparative

analyses of more polluted lakes, especially in thenorthern hemisphere.

2. Study area

The lakes are located at 41”s 71”W (Fig. 1).

The morphometric characteristics are given in

Table 1. Although most of the lakes are set in a

mountainous landscape where glacial geomor-phology predominates, surrounded by well-devel-

oped forests, some, including Nahuel Huapi, may

reach the fringe of the Patagonian Steppe on

their eastern edges. The climate has been charac-

terized as moderately continental (INTA, 1982),ranging from cold temperate near the Andes

Mountains to arid and warmer (desertic) on thePatagonian Plateau (41% 68”W). The prevaiIing

westerl ies lose most of their moisture over the

Andes, resulting in a strong west-to-east precipi-tation gradient. At stations on the Argentine-

Chilean border (1020 m.a.s.1.) precipitation is 2700





3 B. Markert et al. /The Sci ence of the Tot al Environment 206 (1997) I-15

was sampled at two sites: the Tronador and Cate-

dral arms. Lake Guterriez was sampled at itsextreme northern point, while Lake Nahuel Huapi

was sampled of f Puerto Paiiuelo and of f Bar-

iloche City, an area of low pollution on the coast

(only samples for heavy-metal analysis were col-lected at this site). The Upper Manso River, the

main tributary of Lake Mascardi, was also sam-

pled. The sampling of these lakes was done dur-

ing the snow melt period and it is representative

of the end of water column mixing period (Fig. 2).

Spring is a season with increase of light and water

temperature, and accumulation of nutrients. Un-der these high availability of resources an algal

maximum biomass is expected.

The temperature profile was established using

YSI equipment. Conductivity and pH, adjusted to

25°C were measured with potentiometric equip-

ment. Dissolved oxygen was measured by

Winkler’s method, in Lake Nahuel Huapi only.

Water for nutrient analyses was collected using

a Van Dorn bottle at depths of 5 m and 40 m.Samples for heavy-metal analyses were collected

using a Hydro-Bios collector (MERCOS 436 252

model). The samples were immediately trans-

ferred to pre-cleaned polypropylene flasks steril-ized with 1 ml of ultra-pure nitric acid. Phyto-

plankton samples were collected at depths of 5,

10, 20 and 40 m, then integrated to form one

sample and preserved with acetic Lug01 solution.

Chlorophyll concentration was measured in sub-

surface samples (N 0.50 m) extracted with 90%

acetone (APHA, 1985). Eight hundred litres werepumped from a depth of 3-5 m with a peristaltic

pump and passed through a 63-pm sieve and a

25-pm plankton net. For the purposes of this

article the 63-pm fraction will be termed the

‘zooplankton fraction’ and the 25-pm fraction the

‘phytoplankton fraction’. Both fractions were con-

centrated on a 0.45~pm membrane filter for

Temperature (“C)

5 6 7 6 9 IO 11 12 13 14

-30 --

-35 .-

-40 -- r.-

-+a tb -c -cl 1

Fig. 2. Temperature profiles of the Patagonian lakes: (a) Mascardi (Tronador arm); (b) Mascardi (Catedral arm); (c) Gutierrez; and

td) Nahuel Huapi.



B. Markert et al. / The Science of the Total Environment 206 (1997) l-15 5

heavy-metal analysis. A second aliquot of the

63-pm fraction was fixed with sugar-formalin (fi-nal concentration 4% volume) for zooplankton

analyses including analyses of large ciliates.

Nutrients and major ions were determined in the

chemical laboratory of the Centro Regional Uni-

versitario Bariloche as follows: soluble reactivephosphorus (SRP) by molybdate blue, ascorbic

acid reduction; total phosphorus (TP) by persul-

phate oxidation and SRP analysis; nitrates plus

nitrites by cadmium column reduction and diazoic

complexion. Ammonia wa s determined by the in-

dophenol-blue method, calcium and magnesiumby microtitration (EDTA), sodium and potassium

by flame photometry, sulphates by turbidimetry

and alkalinity by titration. All the above standard

analytical methods were performed according to

the recommendations of Standard Methods

(API-IA, 1985). Dissolved inorganic nitrogen(DIN) wa s considered to be the sum of nitrates +

ammonia + nitrites.

Heavy-metal analyses were performed at UFZ

with a commercial total reflection X-ray fluores-

cence spectrometer (TRFX, EXTRA II A,

Atomika Instruments Ltd., OberschleilJheim/Munich, F.R.G.) including Si(Li) detector (resolu-tion 168 eV at 5.9 keV), electronics and a data

processing system. Both MO-tube and W-tube ex-

citation were used for analysis, with tube settings

of 50 kV and lo-38 mA. The measuring time was

uniformly 1000 s for MO-excitation and 2000 s for

W-excitation, Details are given in Reus et al.(1993) and Friese et al. (1997). In addition, sam-

ples were measured with an Elan 5000 device

from the Perkin Elmer/Sciex company. Rhodium

was used as a response element so that matrixinfluences could be taken into account in the

measurements. The samples were measured indiluted (1:lO) and undiluted form. Further details

are given in Markert (1996).

To decompose the plankton samples, 100 mg of

the dried sample were measured into quartz ves-

sels (30 ml) and mixed with 2 ml nitric acid. The

samples were then enclosed in a high-pressureasher (HPA) after KNAPP in Markert (1996).

Tri-distilled water was added to the decomposi-

tion solutions to make a final volume of 50 ml

(Marker& 1996).

The quality of the heavy-metal analysis was

controlled by independent methods (TXRF andICP/MS) and by using standard reference mate-

rials (NIST 1643~ and BCR/CRM 414).

The phytoplankton wa s counted using an in-

verted Hydro-Bios microscope. The diversity in-

dex was calculated by the Shannon-Weaver

method. Crustaceans, rotifers and ciliates were

counted in Bogorov-chambers with an inverted

microscope at a 40 X and 100 X magnification, re-

spectively. The abundance of the large, coloured

ciliates of the genus Stentor w as determined in

parallel with the rotifers. Furthermore, Stentor

was counted on the filters (5 m and 40 m) accord-ing to WSlfl (1995). The determination of the

biomass of ciliates, rotifers and crustaceans fol-

lows the methodology given in detail by Wijlfl

(1995).

4. Results and discussion

4.1. Water temperature

On the sampling days the lakes showed awater-temperature profile typical of the beginning

of the stratification period (Fig. 2). Lakes Gutier-

rez and Nahuel Huapi showed the smallest dif-

ference between surface and deeper waters, while

the Catedral arm of Lake Mascardi exhibited

stratification with the thermocline between 12

and 28 m. Other physical characteristics (pH,conductivity, transparency, depth, geochemical

composition) are given in Tables 2 and 3.

4.2. Quality control

4.2.1. By use of standard reference materials

A comparison of measured and certified values

for the standard reference materials investigated

is given in Table 4.

4.2.2. By comparison of different analytical methods

Figure 3 shows the relationship between stan-

dard and TXRF methods applied to the analysis

of K, Ca and S. Although the replication is low,



h B. Markert et al. / The Science of the Total EnvironrPtent 206 (1997) l-15

Table 2Physical and chemical characteristics of the surface water of Andean-Patagonian lakes

Lake Date Time PH Conductivity

($4 cm-‘)

Transparency

Cm)

Depth (m) insampling site

Nahuel Huapi 26 November 1993 10.00 h 7.01a 30 15 307Gutierrez 25 November 1993 19.30 h 7.48 47 13 100

Mascardi (Catedral arm) 25 November 1993 10.00 h 7.37 43 15 300Mascardi (Tronador arm) 25 November 1993 13.30 h 7.39 42 4 90

a At 5-m depth.

the fit is good for Ca and S, while it is rather poor

for K. The microtitration method used to esti-

mate calcium seems to be very effective at the

low levels typically found in Andean-Patagonian

waters. For sulphates the turbidimetry method

with barium chloride is reliable up to approxi-

mately 1 mg SOi- 1-i. The concentration of

sulphates in Andean-Patagonian waters is close

to the detection limit; the fit against TXRF was

therefore lower than for calcium. For potassium

the figure shows a very slight gradient, suggesting

that flame photometry is unsuitable for the very

low concentrations characteristic of Andean-

Patagonian lakes. It is quite apparent that the

TXRF method increases the sensitivity and dis-

criminating power of the analysis.

4.3. Comparison of the element concentrations in

relation to water depth

Table 5 summarizes the results of the chemical

measurements obtained by standard methods

(API-IA, 1985) and Table 6 the multielemental

composition ascertained by TXRF and ICP.

In Lake Nahuel Huapi, neither of the methodsrevealed differences between the two depths. The

only exception wa s the iron content determined

by TXRF, which wa s higher at 40 m than at 5 m.

The sample taken from a polluted site showed a

significantly higher concentration of Fe and Zn

than those from unpolluted sites. This may be

due to the input of contaminants from Bariloche

City.

Table 3Main elementary composition (%) of rocks from Nahuel Huapi, Mascardi and Gutierrez lakes

LakesRocks

Gutierrez + Mascardi + Nahuel Huapia

Plutonic Metamorphic

Grandodioritic Amphibolites

Nahuel HuapibPyroclastic tuffs

Nahuel HuapibVolcanic basalts,andesites, dacites

SiO,TiO,

%03

FeAFe0

MnO

NOCaO

NazW

pzos

67.57-70.48 52.67-59.86 62.66-74.96 49.86-69.430.43-0.89 0.46-0.87 0.17-0.90 0.41-1.17

14.85-16.22 17.05-18.85 12.21-17.57 14.49-18.06

3.62-4.99 7.34-9.81 0.67-3.02 1.80-5.730.28-0.95 4.03-5.25 0.07-2.04 0.71-3.90

3.01-4.03 0.13-0.20 0.02-0.22 0.12-0.19

0.03-0.086 3.53-5.22 0.34-1.17 0.52-5.361.06-1.49 7.21-9.79 0.45-2.60 1.19-7.994.21-5.5 2.78-3.84 1.90-5.45 3.14-3.91

1.98-2.76 0.31-0.76 0.45-4.75 0.84-3.880.11-0.19 0.10-0.19 0.02-0.10 0.05-0.25

a Data from Dalla Salda et al. (1991).

b Data f rom Spaletti et al. (1982).



B. Markert et al. / The Scie nce of the Tot al Environment 206 (1997) I-15 7

Table 4

Comparison of measured and certified values of the standardreference materials analyzed

NET ICP/MS TXRF BCR/CRM ICP/MS1643~ 414a

As 82.1 81.6 86.7 6.82 6.88

Ca - - (65000) 68420

Cd 12.2 12.8 0.383 0.347

co 23.5 24.1 26.4 (1.43) 1.48

Cr 19 17.8 17.2 23.8 2.5

CU 22.3 22.8 23.2 29.5 28.8

Fe 106.9 - 105.6 185 0 1853

Mn 35.1 33.8 36.3 299 272

Ni 60.6 62.8 60.7 18.8 19.7Pb 35.3 35.9 36.5 3.97 3.3

Sr - - - 261 250

Zn 73.9 79.5 82.5 112 105

a Was not measured by TXRF.Values are given in pg g-’ (ppm) for BCR/CRM 414 on a

dry wt. basis and in pg 1-i (ppb) for NIST 1643~.Figures in brackets give indicative values (not certified).

The TXRF analysis of Lake Gutierrez (Table

6) showed differences between 5 m and 40 m forsulphur only (10% higher at 5 m). This result

coincides with the difference ascertained by tur-

bidimetry (Table 5). The TXRF analysis produced

similar values at both depths for potassium, but

flame photometry revealed a difference of 67%.

This is probably an error of the flame method

resulting from the low K content of the lake

water. For magnesium, the titration method

showed a difference of 30% between the two

depths. However, since the concentration of most

elements is similar at both depths, the differencein magnesium content is more likely to be artifi-

cial.

In the Catedral arm of Lake Mascardi the

differences in ion content in terms of percentages

were greater at 40 m than at 5 m, with the

exception of Si and K. The differences are: HCO,,

8%; Ca, 15%; SO,, 22%; Na, 44% and Mg, 240%.

Such differences were also detected by TXRF: S,

88%; K, 114%; Ca, 101% and Sr, 98%, althoughthe reason for the different concentration at these

depths is not clear. The possibility of sample

contamination can be rejected, since we used

different glassware for each method. The TXRF

K WV’) .450

'400 -- . .

350 --

300 -- l . l . .

250 --

. 200 --

150

10050 y = 0.0842x+ 320.35

0R'= 0.0112

/

0 100 200 300 400 500

TXRF

W9000 T

Ca (pg.f’)

6000J, .

0 2000 4000 6000 6000 10000

TXRF

s bK3.1”)

0 500 1000 1500 2000

S(TXRF)

Fig. 3. Comparison of the results for S, Ca and K between

standard methods (APHA, 1985) and TXRF.

method seems to bring an improvement in the

detection level and supports the results obtained

by standard methods. The different concentrationat the two depths may be explained by the dilu-

tion of surface waters caused by the input of rain

and melted snow. The beginning of the stratifica-

tion period prevents mixing with epilimnetic wa-

ters.

In the Tronador arm of Lake Mascardi theconcentrations ascertained by the TXRF method

were higher at 5 m than at 40 m (Table 6) for S,

33%; Fe, 33%; Zn, 33%; K, 38%; Ca, 36% and



8 B. Markert et al. / The Sci ence of the Tota l Environment 206 (1997) l-15

Table 5Major ion concentration (PM) of Andean-Patagonian lakes analyzed by standard methods (APHA, 1985)

Lake Depth SiO, Na+ K+ Mg2+ Ca2+ HCO,- CI- SO,2-- Sum Z+ Sum A-

(m)

Nahuel Huapi 5 169.17 69.60 7.67 28.80 72.36 93.44 14.10 12.50 279.58 132.55

40 158.67 69.60 7.67 28.80 74.85 90.16 12.50 284.57 115.16Difference % (40 m/S m) -6 0 0 0 3 -4 0

Gutierrez 5 186.00 69.60 7.67 41.14 182.14 250.82 27.08 523.83 304.99

40 184.30 82.65 12.79 53.49 194.61 236.07 30.21 591.63 296.48Difference % (40 m/5 m) -1 19 67 30 7 -6 10

Mascardi (Catedral arm) 5 159.83 39.15 7.67 20.57 117.27 157.38 20.03 21.88 322.50 221.1540 160.33 56.55 7.67 69.94 134.73 170.49 28.13 473.57 226.74

Difference % (40 m/5 m) 0 44 0 240 15 8 22Mascardi (Tronador arm) 5 164.27 60.90 10.23 32.92 137.23 150.82 14.02 30.21 411.41 225.25

40 169.10 60.90 10.23 28.80 144.71 155.74 30.21 418.15 216.15Difference % (40 m/5 m) 3 0 0 -13 5 3 0

Patagonian lake (average) 168.96 63.62 8.95 38.06 132.24 163.11 16.05 24.09

Freshwater world averagea 200.00 273.91 58.83 168.69 374.25 960.66 220.01 116.67 1419 1414

a From Livingstone (1963) in Home and Goldman (1994).

Sr, 38%. On the other hand, standard methods

(Table 5) only showed differences in Mg concen-

tration (12% higher at 5 m). The Upper MansoRiver influences the upper layer of the Tronador

arm, as is apparent from the higher sulphur, iron

and calcium contents. The Upper Manso Riverconveys a considerable amount of dissolved salts

and suspended particles from the Tronador

glacier.

4.4. Transparency, chlorophyll and nutrients

Water transparency was high (13-15 m); thiswas to be expected in view of the low chlorophyll

content, which ranged from 0.10 to 0.24 mg rne3.

Only in the Tronador arm of Lake Mascardi was

the transparency relatively low (4 m) due to the

influence of suspended solids from the UpperManso River. All forms of measured nutrient

concentrations were very low too (Table 71, andwithin the range for oligotrophic or ultra-

oligotrophic lakes of the northern hemisphere

according to the OECD (1982).

The DIN/TP ratio was higher (Table 8) in

Lake Nahuel Huapi (6.8-9.9) than in Lake

Gutierrez (1.2-5.0) and in the two arms of Lake

Mascardi (0.6-1.9). This correlates with the higher

percentage of Cyanophytes in Lake Mascardi(mainly in the Tronador arm) and Lake Gutierrez

(Table 9). Cyanophytes are better competitors

under conditions of low N/P ratios, i.e. below 7:l

(Smith, 1983).

The Fe/SRP ratio ranged between 0.6-1.8 in

Nahuel Huapi, 2.2-3.0 in Lake Gutierrez and 4.2

in the Catedral arm of Lake Mascardi (Table 8).

In the Tronador arm of Lake Mascardi the

Fe/SRP ratio was noticeably higher (11.3-14.3).

The main tributary of Lake Mascardi is the Up-

per Manso River, which discharges into the Tro-nador arm and brings in a heavy load of glacial

sediment rich in Fe and S. The influence of this

input is apparent in the sulphur concentration ofthe Tronador arm, which is similar to that of the

Upper Manso River but about twice that of the

Catedral arm. It has been suggested (Brand, 1991)

that the Fe/PO, ratio of the nutrient inputs

influences the ratio of procaryotes to eucaryotes

in marine phytoplankton communities, with high

Fe/PO, ratios favouring procaryote growth. The

cyanophyte density in the Tronador arm of Lake



B. Markert et al. /The Science of the Total Environment 206 (1997) 1-15 9

ty \4 cl T’. v? 0: A-0 r\13 ,-I3 do0 d

V V vv vvv V

vv vv vv vvv V

r?cr Nr? r‘rc - r?- N00 00 00 000 6vv vv vv vvv V

NN WC-4 P4rJdd dd dd eNr?r N

000 dvv vv vv vvv V

$2r \q crq fc?r: ”00 d0 000

V vv vv vvvg 7



10 B. Markert et al. / The Sc ienc e of the Tota l Environment 206 (1997) l-15

Mascardi was higher than in the Catedral arm;

this coincided with a high Fe/SRP ratio and thelow N/P ratio mentioned above.

4.5. Chemical classi@ation of the lakes investigated

Table 2 shows that the lake waters have a

neutral or slightly alkaline pH (7.01-7.48) as the

vast majority of Andean-Patagonian lakes aroundBariloche (Pedrozo et al., 1993). Table 3 gives the

main elementary composition (%) of rocks from

Nahuel Huapi, Mascardi and Gutierrez lakes. The

waters are very dilute solutions (conductivitybetween 30 and 46.6 $S cm-‘) dominated by

calcium, bicarbonates and dissolved silica. The

ionic composition is largely below the world aver-age given by Livingstone (19631, in: Horne and

Goldman (1994). The relative significance ( peq

1-l ) of the major cations and ions is:

Ca2+ > Mg2+ > < Naf > K+

and

HCO, > SO;- > Cl-

Major ions show an excess of cations in the

charge balance, ranging from 19 to 36%. These

percentage differences were calculated accordingto Lesack et al. (1984) as:

This ionic imbalance cannot be explained bythe SiO, concentration because silicates are ion-

ized as H,SiO; at high pH values (Drever, 1982).

Dissolved silica is below the world average (Table

7). These features of Andean-Patagonian lakes

can be attributed to the dominant igneous rock

(Pedrozo et al., 1993).

The Andean-Patagonian lake water (LWP,,,)

showed concentrations of Cr, Sr, Zn, Cu, Co and

Table 7

Mean element composition ( pg 1-l) of Andean-Patagonian lakes compared with ‘reference freshwater’, world average freshwaterand Lake Constance

As Ca Cd Cl co Cr CU Fe K Mg

Patagonian lakes (avg> nd-< 1.2 5298 < 0.2 569 < 0.2 < l- < 2 < 0.5-2.6 18.8 361 925

Reference freshwater(Markert, 1994) 0.5 2000 0.2 8000 0.5 1 3 500 2000 4000

Fresh water world average(Margalef, 1983) 1.7-3.0 0.2-0.5 0.02-0.6 0.1-1.4 0.83-15

O-10 o-2 5600 6.3-60 1.5-33(Livingstone, 1963) 15 000 7800 0.8 10 - 40 2300 4100

Lake Constance(Sigg, 1985) 0.005-0.01

0.32-0.95

Table 7 (Continued)

Mn Na Ni P Pb S Si Sr Zn

Patagonian lakes (avgl <l-<4 1463 < 0.5- < 1 8 nd- < 2.2 1063 4731 18 2.9

Reference freshwater(Markert, 1994) 5 5000 0.3 20 3 4000 4000 50 5

Fresh water world average(Margalef, 1983) O-10 o-2 5600 6.3-60 1.5-33(Livingstone, 1963) 35 6300 5973 6000 10

Lake Constance

(Sigg, 1985) 0.04-0.010 0.65-1.96



B. Markert et al. / The Sci ence of the Tot al Environment 206 (1997) l-15

Table 8

Nutrient and chlorophyll concentrations in Patagonian lakes

11

Lake Depth NNO, + NNO, NNHh+

(m) CpgNl-‘1 (,qNl-l) :gPI-‘1 :;;P1-‘) $gFel-‘)DIN/TX’ Fe/SRP Chlorophyll aa

(mgCh1 a rnm3)___~-__

Nahuel Huapi 5 29 20 5 3 3 9.9 1.1 0.12

40 9 25 5 3 8 6.8 3.2

Gutierrez 5 43 8 10 3 10 5.0 3.9 0.2440 9 10 15 2 11 1.2 5.4

Mascardi 5 2 6 5 1 1.4 0.10

(Catedral arm) 40 2 3 7 2 13 0.6 7.6

Mascardi 5 3 8 7 2 52 1.4 25.8 0.14

(Tronador arm) 40 8 9 9 2 35 1.9 20.3

a Taken at 0.5 m.

Pb (Table 7) that were of the same order as the similar phytoplankton biomass (134 mg mw3), but

freshwater world average (FWW,,) given by Mar- the densities were very different (1136 cells ml-’

galef (1983). The remaining elements fall below in the Tronador arm and 288 cells ml-’ in the

or are around the limit for the FWW,,. It is Catedral arm>. Lakes Gutierrez and Nahuel Huapisurprising that the Cu, Zn, Pb and Cd levels in also showed a higher biomass level (N 300 mgAndean-Patagonian lakes are similar to or higher rne3) than Lake Mascardi, but the density was

than those given by Sigg (1985) for Lake Con- very different (2256 and 170 cells ml-‘, respec-

stance, that receives far more contaminants. tively). Chlorophyceae and Prymnesiophyceae

However, as far as these heavy metals are groups dominated in density in the Tronador arm,

concerned, the waters of the Andean- but their contribution to the total biomass was

Patagonian lakes and those of Lake Constance low. Dinophyceae wa s the dominant group in the

were close to the lower range of FWW,,. The Fe biomass (54%). The Catedral arm was dominated

and Ca concentrations in ‘reference freshwater’ by Cyanophyceae and Prymnesiophyceae in re-

(REFW) are the only two that differ greatly from spect of density, but the group that contributedthe FFWaVg given by Horne and Goldman (1994). most to the biomass was Dinophyceae (60%).

It is instructive to look at the difference between Bacillariophyceae were dominant both in density

the average lake-water composition of and biomass in Lake Nahuel Huapi and were

Andean-Patagonian waterbodies (LWP& and absent from the Tronador arm of Lake Mascardi.

REFW (Markert, 1994). With the exception of Lake Gutierrez showed Cyanophyceae to be the

calcium, which is twice as high as in REFW, the dominant group in terms of density, but the most

element concentrations (S, Fe, Mg, Na, K and Sr) significant group in respect of biomass was Dino-are lower than in REFW. phyceae (51%).

4.6. Phytoplankton composition 4.7. Zooplankton composition

Phytoplankton density ranged from 170 to 2256

cells ml-‘, while phytoplankton biomass ranged

from 134 to 312 mg m -3 (Table 9). The greatestdivergence (H= 3.23) was ascertained for the

Catedral arm of Lake Mascardi, and the lowest

value (H = 0.78) was estimated for Lake Gutier-

rez. The two arms of Lake Mascardi showed

Zooplankton, including crustaceans, rotifers

and large ciliates, from Lake Mascardi (‘Trona-

dor’, ‘Catedral’) and Lake Gutierrez were countedquantitatively. Due to the filtering procedures,

densities of rotifers and ciliates were most

probably underestimated.

The zooplankton diversity (crustaceans, rotifers)





B. Markert et al. / The Sci ence of the Tot al Environment 206 (1997) 1-15 13

Table 10

Zooplankton of Lakes Mascardi, Gutierrez and Nahuel Huapi

Species

Nauplia (calanoid)Boeckella gracilipes

Cl-C5

MaleMesocyclops longisetus

Cl-C.5

Male

Bosmina sp.

Rotifera

Stentor araucanusStentor amethstinus

Total

Stentor sp. on filters

5 m: Stentor araucanus

5 m: Stentor amethystinus

40 m: Stentor araucanus

40 m: Stentor amethystinus

Mascardi Tronador

D B

3.1150 0.6230

0.1580 0.0670

0.0380 0.0050

0.0130 0.00190.0130 0.0077

0.0150 0.01600.2500 0.0035

3.6000 0.72

6 0.45002 0.1500

Mascardi Catedral

D B

0.8380 0.1620

0.0026 0.0042

0.0013 0.0018

0.0013 0.0017

0.0013 0.00131.5100 0.0021

2.35 0.17

16 1.2000

Gutierrez

D

0.200

0.5200.700

241944.42

15073

3

B

0.040

0.5200.008

1.8001.4203.79

11.2505.4700

0.2200

Notes: D, density (cells ml-‘); B, biomass (mg mm3).

in Lake Mascardi and Lake Gutierrez was low,

which is typical for oligotrophic north Patagonianlakes (Wiilfl, 1995). Whereas in Lake Mascardi

only calanoid (Boeckellu grucilipes) and one cy-

clopoid copepod (Mesocyclops longisetus) were

registered. In Lake Gutierrez only calanoid nau-

plia were found. In both lakes, Bosmina repre-

sented the only cladoceran species. The most

important rotifers in Lake Mascardi were Ker-

atella cochlearis, Polyatihra sp., Ascomo?pha sp.,

Collotheca pelagica, Trichocerca pocillum, Lecane

luna, Synchaeta sp. and Keratella cochlearis, Pol-

yurthra sp. in Lake Gutierrez, respectively.

The zooplankton community of the two sam-

pling stations of Lake Mascardi were quite similar

in species composition, densities (2.35, 3.60 Ind

1-i) and biomass (0.72-0.17 pg C 1-l). The den-

sity and biomass of crustaceans and rotifers in

Lake Gutierrez fall in the same range as those in

Lake Mascardi. In contrast to Lake Mascardi, the

zooplankton community in Lake Gutierrez wasdominated by high abundance and biomass of

Chlorella-bearing, large ciliates (Stentor aruu-

canus, S. amethystinus). Stentor is a common in-

habitant of many (ultra)oligotrophic, north Patag-

onian lakes reaching a high proportion of zoo-

plankton biomass (Wolf?, 1995; Geller et al., 1996).In Lake Gutierrez, Stentor amounted for 3.22 pg

C L-’ or 85% of total zooplankton biomass. This

value, calculated from net samples, probably un-

derestimated the biomass of Stentor. The densi-

ties of the ciliate concentrated on filter are about

five times higher than the net samples (Table 10).

In comparison with Lake Mascardi, the zooplank-

ton biomass in Lake Gutierrez was approximately5-20 times higher. As the filter samples from

Lake Mascardi show, Stentor was present in this

lake in small concentrations, too. It is likely, that

Stentor is an important component of the zoo-plankton community of the lake.

4.8. Chemical composition of the phytoplankton and

zooplankton

Table 11 summarizes the element concentra-

tions in the phytoplankton and zooplankton ofLake Mascardi at two different sites (Catedral

and Tronador). It is noticeable that in all cases

the phytoplankton shows greater accumulations

of the minerals potassium and calcium and the



14 B. Markert et al. / The Sci ence of the Tota l Environment 206 (1997) 1-15

Table 11

Element content of phytoplankton and zooplankton (P and Z) in Lake Mascardi at two different sites in mg kg-’ dry wt.

Sample As Ca CU Fe K Mn Pb S Sr

M. Tronador PM. Tronador Z

Ratio P/Z

M. Catedral P

M. Catedral ZRatio P/Z.-__

7.9 1194.0 20.4 3807.27.8 392.0 2.0 291.2

1.0 3.0 10.2 13.1

7.3 933.0 29.8 741.2

7.4 88.0 1.7 69.21.0 10.6 17.5 10.7

essential trace elements (manganese, iron, copper

and zinc) than the zooplankton. An exception is

sulphur, that occurs in greater concentrations in

zooplankton. The reason would seem to be the

higher protein content of the zooplankton. In the

case of the non-essential elements that are toxic

at higher concentrations (arsenic and lead) it is

noticeable that the levels are more or less similar

for phytoplankton and zooplankton. This indi-

cates that these substances are mainly taken uppassively from the stream of water and deposited

in the cell bodies of the individual organisms. In

general it can be said that the organisms acctmm-

late all the elements loo-fold to lOOO-fold inrelation to the surrounding medium (see Table 6).

5. Conclusion

These first results on biological and chemical

compositions clearly reflect the oligotrophic to

ultra-oligotrophic status of the Argentinean lakes.

These lake systems can be used as ‘reference’ or‘baseline’ systems for further comparative studies

of more polluted lakes, especially in the northern

hemisphere.

Acknowledgements

We wish to thank Mr Pablo Gonzalez and Mr

Walter Lopez for their help in collecting thesamples and Lit. Pedro Temporetti, Bioq. Lucia

Resseli and Lit. Patricia Satti for the laboratory

analyses. M. Mages and C. Hoffmeister per-

formed the TXRF and ICP-MS measurements,respectively. Mrs Marion Brasse, Buchholz,

F.R.G., is thanked for polishing the English of themanuscript.

-

455.5 145.6 61.7 158.5 7.5198.5 14.0 64.7 221.5 2.6

2.3 10.4 1.0 0.7 2.9

293.5 30.6 49.7 230.5 5.074.5 4.7 66.7 1232.5 0.6

3.9 6.5 0.7 0.2 9.0

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