Spatial and Temporal Quality of Water in the Itupararanga Reservoir, Alto Sorocaba Basin (SP), Brazil

doi:10.4236/jwarp.2013.51008

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Journal of Water Resource and Protection, 2013, 5, 64-71

http://dx.doi.org/10.4236/jwarp.2013.51008 Published Online January 2013 (http://www.scirp.org/journal/jwarp)

Spatial and Temporal Quality of Water in the Itupararanga

Reservoir, Alto Sorocaba Basin (SP), Brazil

Felipe José de Moraes Pedrazzi1, Fabiano Tomazini da Conceição1*, Diego de Souza Sardinha2,

Viviane Moschini-Carlos3, Marcelo Pompêo4

1UNESP, Universidade Estadual Paulista, Rio Claro, Brazil

2ICT, UNIFAL, Poços de Caldas, Brazil

3UNESP, Universidade Estadual Paulista, Sorocaba, Brazil

4IB, USP, São Paulo, Brazil

Email: *[email protected]

Received October 30, 2012; revised November 30, 2012; accepted December 8, 2012

ABSTRACT

Considering the great importance of the Itupararanga Reservoir, Upper Alto Sorocaba basin/SP, this study aimed to

report the variations of some parameters of water quality in the spatial and temporal gradients in this multipurpose res-

ervoir. The eutrophication of this reservoir was checked using the Carlson Index Modified and the results indicate that

the surface water were classified as eutrophic and mesotrophic in wet and dry periods, being characterized the better

quality of water in wet period. In the vertical gradient the results showed a stratiphication in all parameters analyzed,

except for the electrical conductivity, with good correlation between total phosphorous and chlorophyll-a, indicating

that eutrophication of the reservoir changes the conditions of algal growth, mainly in its initial area. Immediate inter-

ventions are needed, which must be directed to planning of land use, domestic effluents treatment, taking to an inte-

grated management of this important watershed located in the São Paulo State.

Keywords: Itupararanga Reservoir; Limnology; Eutrophication; Environmental Management

1. Introduction

Water is available in various forms, one of the most

common and important substances found in nature,

covering about 70% of the Earth surface. Fresh water

represents only 2.5% of total water in nature, and the

remaining 97.5% are found in oceans and seas salty.

However, only 0.3% is fresh water exploitable for human

activities, can be drawn from lakes, rivers and aquifers.

The remainder is contained in aquifers, deep aquifers, polar

ice caps, glaciers, permanent snow and other reservoirs.

Recent data show that 1.7 billion people presently live

without water with adequate quality; a number that may

increase to 3.3 billion in 2020 and that may cause con-

flicts if effective water management is not performed.

The classification of water bodies is usually established

according to legal standards and it should be expected to

be improved over time. In Brazil, this classification was

made by Resolution CONAMA (National Council for

Environment) No 357, that defines freshwaters (special,

1, 2, 3 and 4 classes), brackish waters (special, 1, 2 and 3

classes) and saline waters (special, 1, 2 and 3 classes) [1].

São Paulo Electric Company, known as “Light” built

Itupararanga reservoir (Figure 1) in 1912, the aim was

generate electricity to the cities around Votorantim. Later,

in 1976, Companhia Brasileira de Aluminio (CBA) bought

the rights to operate the hydroelectric power generation

for the aluminum industry. This reservoir is located at the

Upper Sorocaba basin, which has its economy based

mainly on agricultural production, where many affluents

compose this basin tributaries that give rise to the Sorocaba

River, which flows into the Itupararanga Reservoir. This

reservoir has fundamental importance in regulating the

hydraulic regime of the Sorocaba River and in the public

supply of the region, serving approximately one million

people in the municipalities of Ibiúna Sorocaba, Votorantim

and Mairinque. However, this reservoir has lack of infor-

mation about its quality, making it essential to carry out

more detailed limnological studies. Thus, the purpose of

this study was to evaluate the water quality in spatial and

temporal scales in Itupararanga Reservoir, São Paulo

State. The results allowed generating an environmental

assessment by providing grants for planning and manage-

ment of pollution control in this important watershed

located in the interior of São Paulo State.

2. Overview of the Alto Sorocaba Basin

Alto Sorocaba basin covers an area of 929 km2 (Figure 1)

*Corresponding author.

F. J. DE M. PEDRAZZI ET AL. 65

and it is located in the southeastern part of São Paulo

State, between coordinates 23˚45'37''S and 23˚35'02''S

and 47˚21'00''W and 46˚57'29''W. Una, Sorocabuçu, and

Sorocamirim rivers are the main formed the Sorocaba

River, crossing Ibiúna, Cotia, Vargem Grande Paulista,

and São Roque cities. The total population of Alto Soro-

caba basin is 110,577 inhabitants, with an urbanized area

occupying approximately 71 km2, being 55 km2 charac-

terized by small villages. The main land use in this basin

is characterized for an intense agricultural activity of

cabbage, lettuce, potato, and tomatoes crops (393 km2).

The Alto Sorocaba basin is composed for rocks dating

since Medium-Upper Proterozoic until Quaternary des-

ignated the São Roque Group and Embu Complex. The

São Roque Group is formed for metamorphic rocks asso-

ciated with granitic complexes, such as San Francisco

(sienogranites and monzogranites) and São Roque (dio-

rites and granodiorites) granites [2]. The Embu Complex

presents paragneisses and migmatites also associated

with Ibiúna (monzogranites and sienogranites) and Caucaia

(monzogranites and sienogranites) granites [2]. Among

the major types of soils occurring in the Alto Sorocaba

basin, yellow-red ultisols and oxisols cover about 85% of

the area of the basin.

The climate of the region is Cwb type (Köeppen clas-

sification), i.e. tropical rainy weather characterized by

wet summer (October through March) and dry winter

(April through September). The average temperature in

almost all months is higher than 18˚C, reaching 22˚C in

the hottest one (December). The area often has 55 - 65

days of rain per year, with more than 80% of the precipi-

tation falling between October through March. For more

than 50% of the year (October-April) the area is domi-

nated by tropical and equatorial air masses, with the

winds coming from the S and SE. The mean annual rain-

fall was 1493 mm between 1960 and 2004 [3]. Figure 2

shows both the monthly average precipitation and dis-

charge at Itupararanga Reservoir, which indicates that the

Sorocaba River regime is directly bounded to rainfall, as

expected. Beside, the discharge at Itupararanga Reservoir

is approximately 12 m³/s in 50% of the time (Figure 3),

being this value slightly smaller than the monthly aver-

age discharge into Itupararanga Reservoir, i.e. 12.7 m³/s

[3].

Figure 1. Simplified geological map of the Alto Sorocaba basin and location of sampling points in the Itupararanga Reser-

voir.

Figure 2. Monthly average rainfall and discharge into Itu-

pararanga Reservoir between 1960 and 2004.

Figure 3. Permanence curve of discharge into Itupararanga

Reservoir between 1960 and 2004.

F. J. DE M. PEDRAZZI ET AL.

3. Sampling and Analytical Techniques

To define the sampling points in the reservoir, an explora-

tory field trip to visit was made to check the level of an-

thropogenic influence. After this stage, to assess the quality

of water in the spatial scale, was chosen 20 sampling points

for collecting surface water samples evenly distributed

throughout the Itupararanga Reservoir and 2 points for a

vertical sampling, to assess the profiles of water column

(P1 and P2), this points were located one near the beginning

and one in the end of the reservoir (Figure 1).

To the assessment of the quality of water in the reservoir

timescale, there were two collection campaigns in different

seasons, one during the wet season (01/24/2007 and 01/

25/2007) and another in dry season (08/01/2007 and 08/

02/2007). To collect samples of surface water, containers

(high density polyethylene) were previously prepared to

receipt of samples. For the sampling of vertical profiles,

were used a bottle of Van Dorn. Water transparency was

measured with Secchi Disc to assess the disappearance

depth4.

On-site collection, all water samples (surface or vertical

profile) were characterized by following variables: water

temperature (Temp, ˚C), pH, electrical conductivity (EC,

S/cm) and dissolved oxygen (DO, mg/L). The equipment

used for these measurements were YSI, YSI 556 model.

The pH electrode is combined type and patterns of high

purity were used for calibration of pH 4.00 (4.005 ±

0.010 at 25˚C ± 0.2˚C) and 7.00 (7.000 ± 0.010 at 25˚C ±

0.2˚C). The conductivity meter was calibrated using a

standard solution of KCl (1.0 mmol/L) of known conduc-

tivity, i.e. 147 μS/cm at 25˚C.

All samples were stored properly preserved and brought

to the Laboratory of Environmental Geochemistry at

UNESP-Sorocaba. In the laboratory each sample was

divided into two aliquots for quantification of total pho-

sphorus (TP) and chlorophyll-a (Cl). The first aliquot

was measured the total phosphorous concentration, in

this laboratory, using the method of acid digestion with

potassium persulfate through the spectrophotometer DR-

2800 Hach Company. The second aliquot was transported

to the Laboratory of Limnology at USP-São Paulo, fil-

tered and Chlorophyll-a was determined according to

Wetzel and Likens [4].

Trophic State Index (TSI) characterization of the Itu-

pararanga Reservoir was calculated according to Carlson

modified, used as default in São Paulo State [5], which it

is composed for Trophic State Index to total phosphorous

—TSI(TP) and Trophic State Index to chlorophyll-a—

TSI(Cl). With the results, it was possible to evaluate the

Trophic State Index of the Itupararanga Reservoir as

oligotrophic (TSI < 44), mesotrophic (44 < TSI < 54),

eutrophic (55 < TSI < 74) e hypereutrophic (TSI > 74)

[5]. The statistical tests among the parameters analyzed

were evaluated using Pearson Correlation Test and the

spatial distribution of the Trophic State Index was ob-

tained through the software Surfer for Windows.

4. Results and Discussion

Tables 1 to 4 present the results obtained in this work to

spatial and temporal water quality characterization of the

Itupararanga Reservoir. The results for the Pearson Cor-

relation Test are presented in Tables 5 and 6. Figures 4

and 5 show the temperature, pH and dissolved oxygen

and total phosphorous and chlorophyll-a profiles, respec-

tively.

The depth of the Secchi Disk was 4 and 8 m at points

P1 and P2, respectively, in the first sampling, 01/24/2007,

indicating that the aphotic zones are below 5 and 9 m.

Already during the second stage of sampling (01/08/

2007), the depth of the Secchi Disk was 9 m to 10 m,

with a photic zone of 10 and 12 m for the points P1 and

P2, respectively. With these results it was possible to iden-

tify the trophic zone for both sampling sites increased

50% (P1) and 33% (P2) for the driest period. This dif-

ference can be attributed to a larger input of suspended

sediment entering the Itupararanga Reservoir in the rainy

season due to the laminar erosion and, consequently,

reducing waters clarity and the photic zone.

Table 1. Quality of surface water in the Itupararanga Res-

ervoir in wet period: 01/24/2007.

DO TP

Point EC

(S/cm)

Temp

(˚C) pH

(mg/L)

(g/L) TSI

1 60.00 26.707.00 5.20 0.18 8.49 62

2 60.00 27.307.20 7.00 0.20 27.8169

3 60.00 27.907.50 8.10 0.14 9.23 60

4 60.00 27.107.60 8.60 0.19 13.9065

5 70.00 27.907.50 8.30 0.15 6.38 59

6 70.00 28.907.50 7.70 0.15 6.22 59

7 60.00 27.207.60 8.40 0.14 4.95 57

8 70.00 27.907.50 8.10 0.11 4.14 55

9 70.00 27.207.70 7.70 0.11 2.11 51

10 70.00 27.207.50 7.10 0.10 2.11 51

11 70.00 28.207.50 7.30 0.09 1.75 49

12 70.00 26.607.60 7.60 0.09 1.62 49

13 70.00 28.007.60 7.40 0.10 0.67 45

14 70.00 27.507.60 7.70 0.11 2.48 52

15 70.00 28.507.50 7.80 0.09 1.19 47

16 70.00 26.307.70 7.90 0.09 1.27 47

17 70.00 28.307.70 7.80 0.11 0.83 47

18 70.00 27.507.70 7.90 0.11

0.51 44

19 70.00 26.807.70 7.90 0.08 0.84 44

20 50.00 26.607.60 8.00 0.07 0.99 44

F. J. DE M. PEDRAZZI ET AL. 67

Table 2. Quality of surface water in the Itupararanga Res-

ervoir in dry period: 08/02/2007.

DO TP

Point EC

(S/cm)

Temp

(˚C) pH

(mg/L)

C-a

(g/L) TSI

1 60.00 12.40 6.605.00 0.20 5.50 60

2 70.00 14.80 6.906.80 0.23 18.1067

3 60.00 15.70 7.507.90 0.16 5.66 59

4 70.00 15.90 7.408.00 0.19 8.92 62

5 70.00 16.00 7.408.10 0.16 8.33 61

6 70.00 16.30 7.408.10 0.15 9.59 61

7 70.00 16.80 7.507.80 0.14 9.44 61

8 70.00 17.00 7.408.00 0.11 8.88 59

9 70.00 16.00 7.607.60 0.10 9.39 58

10 70.00 17.10 7.707.80 0.10 4.82 55

11 70.00 16.80 7.408.10 0.10 4.86 55

12 70.00 17.00 7.407.50 0.10 4.95 55

13 70.00 17.00 7.507.60 0.11 4.49 55

14 70.00 16.90 7.407.50 0.10 5.07 55

15 70.00 16.80 7.607.50 0.09 5.10 55

16 70.00 17.10 7.407.40 0.11 4.61 55

17 60.00 16.90 7.507.70 0.12 4.29 55

18 70.00 16.90 7.407.60 0.11

3.93 55

19 60.00 16.80 7.407.60 0.08 3.19 51

20 60.00 16.30 7.507.60 0.07 3.16 50

Table 3. Results of water profile in the Itupararanga Reser-

voir in wet period: 01/24/2007.

DO TP

Depth

(m)

(S/cm)

Temp

(˚C) pH

(mg/L)

C-a

(g/L) TSI

Profile P1

0.00 70.00 16.30 7.40 8.10 0.15 9.5961

2.00 70.00 16.00 7.40 7.90 0.18 12.5864

4.00 70.00 15.30 7.50 6.90 0.20 14.4165

6.00 70.00 15.20 7.10 6.60 0.17 12.9764

8.00 70.00 15.00 7.00 6.40 0.11 13.5461

10.00 70.00 14.50 6.50 4.50 0.08 4.4753

Profile P2

0.00 65.00 17.10 7.40 7.40 0.11 6.3457

2.00 65.00 16.50 7.50 7.20 0.13 7.6659

4.00 65.00 16.30 7.70 6.80 0.18 11.0063

6.00 65.00 15.90 7.50 6.40 0.14 8.2160

8.00 65.00 15.80 6.70 6.00 0.10 6.8256

12.00 65.00 15.00 6.50 4.10 0.07 4.0951

Table 4. Results of water profile in the Itupararanga Res-

ervoir in dry period: 08/02/2007.

DO TP

Depth

(m)

(S/cm)

Temp

(˚C) pH

(mg/L)

C-a

(g/L) TSI

Profile P1

0.00 70.00 16.307.40 8.10 0.15 9.5961

2.00 70.00 16.007.40 7.90 0.18 12.5864

4.00 70.00 15.307.50 6.90 0.20 14.4165

6.00 70.00 15.207.10 6.60 0.17 12.9764

8.00 70.00 15.007.00 6.40 0.11 13.5461

10.0070.00 14.506.50 4.50 0.08 4.4753

Profile P2

0.00 65.00 17.107.40 7.40 0.11 6.3457

2.00 65.00 16.507.50 7.20 0.13 7.6659

4.00 65.00 16.307.70 6.80 0.18 11.0063

6.00 65.00 15.907.50 6.40 0.14 8.2160

8.00 65.00 15.806.70 6.00 0.10 6.8256

12.0065.00 15.006.50 4.10 0.07 4.0951

Table 5. Relationship among all parameters obtained for

surface waters from Itupararanga Reservoir (P ≤ 0.01).

Wet period

EC Temp pH DO TP Cl

EC 1.00

Temp 0.38 1.00

pH 0.35 –0.01 1.00

DO 0.05 0.15 0.56 1.00

TP –0.350.08 –0.32 –0.21 1.00

C-a –0.45–0.03 –0.31 –0.17 0.85 1.00

Dry period

EC Temp pH DO TP C-a

EC 1.00

Temp 0.38 1.00

pH 0.23 0.55 1.00

DO 0.35 0.41 0.53 1.00

TP 0.01 –0.73 –0.48 –0.40 1.00

C-a 0.38 –0.34 –0.35 –0.05 0.81 1.00

F. J. DE M. PEDRAZZI ET AL.

Temperature ( C)

Depth (m)

Wet period

Temperature ( C)

Depth (m)

Dry period

DO (mg/L)

Depth (m)

Dry period

DO (mg/L)

Depth (m)

Wet period

Depth (m)

Dry period

Depth (m)

Wet period

Figure 4. Temperature, pH and dissolved oxygen profiles in the Itupararanga Reservoir.

Total phophorous (mg/L)

Depth (m)

Wet period

Depth ( m)

礸

Chlorophyll-a (

Wet period

Depth (m)

Dry period

Total phophorous (mg/L)

Depth (m)

Dry period

礸

Chlorophyll-a (/L)

Figure 5. Total phosphorous and chlorophyll-a profiles in the Itupararanga Reservoir.

F. J. DE M. PEDRAZZI ET AL. 69

The electrical conductivity depending on temperature

and amount of dissolved ions present. The electrical

conductivity parameter does not determine specifically

which ions are present in a given sample of water, but

can contribute to possible recognition of environmental

impacts that occur in the drainage basin. The conductivity

values are presented fairly constant throughout the reservoir

and in the vertical profiles in both seasons, ranging between

60 and 70 μS/cm.

This same behavior was also found by Mariani [6] for

Riacho Grande Reservoir, which is the compound that

supplies the Billings, located in the metropolitan area of

São Paulo. Studies such as Calijuri et al. [7], Bicudo et al.

[8] and Mariani [6] conducted in eutrophic reservoirs

especially for industrial and domestic sewage, showed

values above 150 μS/cm for electrical conductivity in

these reservoirs. Thus, the results of electrical conductiv-

ity can be considered low for surface water, indicating

that the Itupararanga Reservoir still has good quality of

water.

Temperature is a determining factor in driving the

reactions that affect the chemical, physical and biological

processes and thus have an enormous influence on bio-

logical activity and growth of aquatic organisms. With

the temperature change, algae and photosynthetic micro-

organisms may distance themselves from the water sur-

face by migration or even death. It is observed that in the

rainy season, water temperature at the surface is consi-

derably greater than in the dry season, i.e. variation be-

tween 26.30˚C to 28.90˚C and 12.40˚C to 17.10˚C,

respectively. In the dry period is noted an increase of

about 4˚C between point 1 and 20, due to collection start

the morning with cooler temperatures, and end in the

afternoon, with heating this shell throughout the day due

to higher solar radiation.

According to Tundisi [9], the stratification of the water

column must be greater in summer, which can be found

in both vertical profiles studied, i.e., stratification of about

3.5˚C and 2.0˚C during wet and dry periods, respectively.

Moreover, for both profiles, the higher temperature were

characterized in samples collected near the surface, as

also found for the Rio das Pedras Reservoir [10]. In other

studies performed in Brazilian reservoirs, usually the

lowest temperature are characterized on the water surface,

due to air temperature and intensity of local wind, as was

the case of the Rio Paranapanema Lake/SP [11], Jurumirim

Reservoir/SP [12], Lobo Reservoir/SP [13] and Riacho

Grande Reservoir/SP [6].

The pH is a measure of balance between of hydroxyl

(OH–) and hydrogen ions (H+), being used to identify

whether a solution is acidic, neutral or basic. With respect

to pH, there is close relationship between plant and animal

communities and aquatic. On communities, the pH is

directly involved in the processes of cell membrane

permeability, thereby interfering in the ionic transport

within the cell, and between organisms and the environ-

ment. The criteria to protect aquatic life that set the range

of pH should be ranging from 6 to 9, as established in

Brazil for surface water Class II [1]. All pH values ob-

tained for the Itupararanga Reservoir in horizontal and

vertical scaling are proposed within this range.

The higher pH values, both at horizontal or vertical

scales, occurred during the rainy season. In horizontal

scale, it is observed that the lower pH values in both

samples were always obtained between points 1 and 2,

being these values close to the Sorocaba River before it

enters the Itupararanga Reservoir, where has a charge of

domestic effluents.

In the other sampling points there was small variation

in pH values remained between 7.50 and 7.70 and 7.40

and 7.60 for wet and dry seasons, respectively. The in-

crease in pH may be due to photosynthetic activity oc-

curring in the Itupararanga Reservoir, which removes

CO2 and 3

HCO



, and tamper with the carbonate buffer

system. Vertical scale for both sites and sampling periods,

it is possible to observe a slight stratification in pH,

which remained practically constant in the first meters of

water column, with a gradual decrease until the deeper

sites, located in the aphotic zone. The lower pH values in

the regions close to the bottom of the reservoir are expected

due to chemical oxidation of organic matter by anaerobic

bacteria, as already observed in Riacho Grande Reservoir

[6].

Among the dissolved gases in water, oxygen is one of

the most important parameter to dynamic characteriza-

tion of aquatic ecosystems. The main sources of oxygen

to water are the atmosphere and photosynthesis. On the

other hand, the losses are due to consumption by the

decomposition of organic matter (oxidation), exchanges

in the atmosphere, respiration of aquatic organisms and

oxidation of metal ions, such as iron and manganese.

Samples collected in both sampling periods indicates the

dissolved oxygen concentration in horizontal and vertical

scale values were above 5.0 mg/L, minimum value

established by CONAMA 357 to Class II waters [1]. The

exception was for the sampling points in vertical scale

located in the aphotic zone, where the dissolved oxygen

values were always below 5.0 mg/L.

The lowest levels of dissolved oxygen in both horizontal

and vertical scale occurred in the dry season, in the

points 1 and 2 due to decomposition of organic matter

from the domestic wastewater of Ibiúna. After this region,

the dissolved oxygen values increase along the reservoir,

being this fact attributed to photosynthetic activity.

The values of dissolved oxygen concentration in vertical

scale decrease with depth. According to Tundisi [9] and

Lampert and Sommer [14], in many cases, a decreasing

gradient of temperature causes a decreasing gradient of

F. J. DE M. PEDRAZZI ET AL.

dissolved oxygen. Statistical tests of correlation between

temperature and dissolved oxygen (r = 0.75 (P1), and r =

0.90 (P2), in wet period and r = 0.95 (P1), and r = 0.94

(P1), in dry period, Table 6) indicate that the temperature

must control the concentration of dissolved oxygen in the

vertical scale Itupararanga Reservoir, as already described

for the Rio das Pedras Reservoir [10]. Moreover, the

dissolved oxygen values characterized the sampling points

located in the photic zone in both sampling periods in-

dicate no anoxia at the bottom of the reservoir.

Trophic State Index (TSI)

Phosphorus is an essential element for the metabolism of

living beings, which acts as the energy storage (ATP)

and the structuring of the plasma membrane, composed

of phospholipids. The amount of chlorophyll-a is directly

related to the phytoplankton biomass, and consequently

with the total production of the lakes. In terms of total

phosphorus and chlorophyll-a, all samples were higher

for phosphorus and lower to clorophyll-a in relation to

allow by CONAMA 357 for Class II waters [1], which

indicates the maximum concentration for both parameters

Table 6. Relationship among all parameters obtained for

water profiles from Itupararanga Reservoir (P ≤ 0.01).

Wet period (P1)

EC Temp pH DO TP Cl

EC 1.00

Temp 0.13 1.00

pH 0.09 0.40 1.00

DO 0.46 0.75 0.59 1.00

TP 0.24 0.51 0.83 0.51 1.00

C-a –0.39 –0.25 0.90 0.43 0.791.00

Wet period (P2)

EC Temp pH DO TP C-a

EC 1.00

Temp 0.19 1.00

pH 0.11 0.53 1.00

DO 0.50 0.90 0.51 1.00

TP –0.29 0.12 0.92 0.43 1.00

C-a –0.51 –0.32 0.74 –0.02 0.861.00

Dry period (P1)

EC Temp pH DO TP C-a

EC 1.00

Temp 0.31 1.00

pH 0.34 0.41 1.00

DO 0.51 0.95 0.49 1.00

TP 0.32 0.33 0.89 0.78 1.00

C-a –0.22 0.31 0.72 0.58 0.741.00

Dry period (P2)

EC Temp pH DO TP C-a

EC 1.00

Temp 0.21 1.00

pH 0.31 0.45 1.00

DO 0.44 0.94 0.47 1.00

TP 0.54 0.47 0.88 0.41 1.00

C-a –0.36 0.01 0.80 0.12 0.751.00

as 0.030 mg/L.

The highest values of total phosphorus in horizontal

and vertical scale were quantified in the dry season. In

horizontal scale for both sampling periods, the highest

values of this parameter are among the sampling points 1

and 9, being the highest values found in sampling point 2.

After this region, the values of total phosphorus decreases

in downstream direction, indicating that the Itupararanga

Reservoir acts as a restraint of substances than those who

flock to it, possibly due to sedimentation, absorption and/

or complexation of these substances. Regarding the

distribution of total phosphorus in vertical scale, could be

observed a well-marked stratification for both sampling

periods, with higher values being quantified up to four

meters deep, with a subsequent gradual decrease to the

deep zones of the Itupararanga Reservoir.

In the dry period there was greater chlorophyll-a con-

centration along the Itupararanga Reservoir in horizontal

and vertical scale, indicating greater population of algae

in the reservoir. Chlorophyll-a vertical profiles show

eutrophic patterns environments, with lower concentrations

in regions of greater depth. Statistical tests indicates a strong

correlation between total phosphorus and chlorophyll-a

for surface waters in the Itupararanga Reservoir in both

sampling periods (r = 0.85 and 0.81 in wet and dry

periods, respectively, Table 5), suggesting that the be-

haviors of these parameters must be correlated. It was

also possible to find a correlation between total phosphorus

and chlorophyll-a in the both vertical profiles and samp-

ling periods (r = 0.79 (P1) and r = 0.86 (P2) in wet period

and r = 0.75 (P1) and r = 0.74 (P2) in dry period, Table 6).

According to the TSI, the Itupararanga Reservoir was

classified as mesotrophic and eutrophic in wet and dry

periods, with a better quality of water in the Itupararanga

Reservoir found in the wet season. As shown in Figure 6,

Wet per

Dry period

Oligotrophic

Mesotrophic

Hypereutrophic

Eutrophic

Legend

Scale

04812 16 20 k

Figure 6. Trophic State Index (TSI) in the Itupararanga Res-

ervoir in wet and dry period.

F. J. DE M. PEDRAZZI ET AL.

the points with higher values of TSI in the Itupararanga

Reservoir, in both sampling periods, where observed

mainly among the sampling points 1 up to 4, causing

excessive growth of aquatic autotrophs, making harder

the navigation in this section due to green algae blooms.

This fact is directly linked to the Sorocaba River,

which before discharging in the Itupararanga Reservoir,

suffers severe environmental impacts, affecting their qua-

lity. The Ibiúna city does not possess effluents treatment

planning, and, disposes almost 100% of domestic and

industrial effluents into the Una River. The Sorocabuçu

and Sorocamirim rivers do not pass through any urban

center. However, these rivers receive diffuse pollutants

due to the vegetables crops (cabbage, lettuce, potatoes,

and tomatoes, among others) and presence of small vil-

lages along its length and livestock [15]. Finally, there is

an improvement in quality of water after the sampling

point 4, mainly in wet period.

There are two explanations for the increase in the TSI

value in dry period, as already evidenced in Ponte Nova-

Alto Tietê [16] and Rio Grande-Billings Complex [6].

The first explanation is due to rapid eutrophication of the

Itupararanga Reservoir caused by the land use of the

Upper Alto Sorocaba basin. The second explanation is

the algae persistence in this reservoir, which were proli-

ferated and spread throughout the summer. However, the

chlorophyll-a concentration must decrease until the next

summer together with the water temperature of the Itu-

pararanga Reservoir. Only a more detailed study with a

monthly sampling during one or two complete hydrologi-

cal cycles can confirm which of the hypotheses should be

accepted.

5. Acknowledgements

The authors thank CAPES for the scholarship to F. J. M.

Pedrazzi, and the Ibiúna municipally police and SOS Itu-

pararanga for the operational support during this study.

REFERENCES

[1] CONAMA (Conselho Nacional do Meio Ambiente), “Re-

solução No 357, de 17 de Março de 2005,” CONAMA,

MMA, Brasília, 2005.

[2] A. M. Godoy, “Estudos Geológicos das Rochas granitói-

des e Metamórficas e Suas Aplicações Como Rochas Or-

namentais e de Revestimento: Sistematização Crítica da

Produção Técnico-Científica,” Tese de Livre Docência,

IGCE, UNESP, Rio Claro, 2003.

[3] CBA (Companhia Brasileira de Alumínio), “Dados de

Vazão e Precipitação. Estação Meteorológica na Represa

de Itupararanga,” Votorantim (SP), Relatório Interno,

2006.

[4] R. G. Wetzel and G. E. Likens, “Limnological Analises,”

2nd Edition, Springer Verlag, New York, 1991.

[5] CETESB (Companhia de Tecnologia de Saneamento

Ambiental), “Relatório de Qualidade das Águas Interiores

do Estado de São Paulo, 2007,” SMA, São Paulo, 2008.

[6] C. F. Mariani, “Reservatório Rio Grande: Caracterização

Limnológica da Água e Biodisponibilidade de Metais-

Traço No Sedimento,” Tese de Doutorado, USP, São

Paulo, 2006.

[7] M. C. A. Calijuri, G. L. B. Deberdt and R. T. Minoti, “A

Produtividade Primária Pelo Fitoplâncton Na Represa de

Salto Grande,” In: R. Henry, Ed., Ecologia de Reser-

vatórios: Estrutura, Função e Aspectos Sociais, FUNDI-

BIO/FAPESP, Botucatu, 1990, pp. 109-148.

[8] D. C. Bicudo, M. C. Forti, F. C. D. Carmo, C. Bourotte, C.

E. M. Bicudo, J. A. Melfi and Y. Lucas, “A Atmosfera, as

Águas e Os Reservatórios Do PEFI: Caracterização Quí-

mica,” In: D. C. Bicudo, M. C. Forti and C. E. M. Bicudo,

Eds., Parque Estadual das Fontes de Ipiranga (PEFI):

Unidade de Conservação Que Resiste à Urbanização de

São Paulo, SMA, São Paulo, 2000, pp. 161-200.

[9] J. G. Tundisi, “Impactos Ecológicos da Construção de

Represas: Aspectos Específicos e Problemas de Manejo,”

In: J. G. Tundisi, T. Matsumura-Tundisi, R. Henry, O.

Rocha and K. Hino, Eds., Limnologia e Manejo de Re-

presas, EESC-USP/ CRHEA/ACIESP, São Carlos, 1988.

[10] P. R. Padial, M. L. M. Pompêo and V. Moschini-Carlos,

Heterogeneidade Espacial e Temporal da Qualidade da

Água No Reservatório Rio das Pedras (Complexo Billigs,

São Paulo),” Revista Ambienta e Água, Vol. 4, No. 3,

2009, pp 35-53. doi:10.4136/ambi-agua.101

[11] V. Moschini-Carlos, M. L. M. Pompêo and R. Henry,

“Caracterização Limnológica de Uma Baia Marginal ao

Rio Paranapanema (Zona de Desembocadura Na Represa

de Jurumirim, SP),” Acta Limnologica Brasiliensia, Vol.

10, No. 2, 1998, pp. 1-19.

[12] R. Henry, E. D. Carvalho, M. G. Nogueira, M. L. Pompêo,

V. Moschini-Carlos, C. M. Santos, S. C. Luciano and C.

Y. Fujihara, “The Jurumirim Reservoir,” Proceedings of

XXVI International Congress of Limnology, São Paulo,

1995, pp. 13-33.

[13] A. J. Deberdt, “Variação Nictimeral de Variáveis Lim-

nológicas No Reservatório de Salto Grande (Americana-

SP),” Dissertação de Mestrado, EESC, USP, São Carlos,

1999.

[14] W. Lampert and U. Sommer, “Limnoloecology: The Eco-

logy of Lakes and Streams,” Oxford University Press,

Oxford, 1997.

[15] D. S. Sardinha, F. T. Conceição, D. M. Bonotto, M. H. D.

Salles and V. A. Angelucci, “Avaliação do Balanço An-

ual de Cátions e Ânions Na Bacia Do Alto Sorocaba

(SP),” Revista Brasileira de Geociências, Vol. 38, No. 4,

2008, pp. 730-740.

[16] A. J. M. Junior, “Caracterização Limnológica e Comparti-

mentação do Reservatório de Ponte Nova,” Alto Tietê/SP,

Tese de doutorado, USP, São Paulo, 2006.