ORIGINAL ARTICLE

Hydrochemical and stable isotopes (H, O, S) signatures in deepgroundwaters of Parana basin, Brazil

Albert Soler i Gil • Daniel Marcos Bonotto

Received: 27 October 2013 / Accepted: 27 May 2014

� Springer-Verlag Berlin Heidelberg 2014

Abstract This paper describes a hydrochemical (major

and trace elements) and stable isotopes (H, O, S) study of

rainwater and groundwater in a Guarani Aquifer System

(GAS) transect at Sao Paulo State, Brazil. The Brazilian

Code of Mineral Waters (BCMW) was adopted for the

groundwater temperature classification, allowing adequate

insights in the hydrochemical data. 2H and 18O data in circa

580 rainwater samples at Sao Paulo State have been

selected, showing a wide dispersion (d18O from -21.5 to

?4.9 % V-SMOW; d2H from -162 to ?43.2 %V-SMOW). The 2H and 18O data in groundwater did not

vary significantly, fitting the regional meteoric water line

and indicating that the groundwater origin is directly

related to the meteoric water precipitation. The d18O values

in groundwater collected along the GAS transect did not

indicate a tendency towards more negative values accord-

ing to the groundwater flow direction at Sao Paulo State as

suggested elsewhere. The d18OSO4 and d18Owater data

indicated that the dissolved sulfate is obtained from pre-

vious sulfate dissolution. The d34S and d18Osulfate data of

dissolved SO42- suggested that the dissolution of evapor-

ites and bacterial SO42- reduction processes may be

occurring at the GAS. The temperature, redox potentials,

dissolved oxygen and organic matter content in the

sediments provided an ideal environment for the d34S and

d18Osulfate changes along the GAS transect, accompanying

the groundwater flow direction.

Keywords Groundwater � Hydrochemistry � Stable

isotopes � Parana sedimentary basin

Introduction

The huge transboundary Guarani Aquifer System (GAS)

consists of Triassic–Jurassic eolian-fluvio-lacustrine sand-

stones confined by thick (up to 1,500 m) Cretaceous basalt

flows of the Serra Geral Formation (Almeida and Melo

1981). It has continental dimensions, extending about 1.2

million km2 within the Parana sedimentary basin, South

America (Araujo et al. 1999). The total number of wells

drilled in GAS is about 1,500 and the estimated number of

inhabitants living above it is more than 90 million (Gast-

mans et al. 2010a). The GAS represents an important

hydrological resource as water from this basin is exten-

sively used for drinking purposes, inclusive in many water-

supply systems that utilize them at least as part of their

networks.

The GAS has been focused under different approaches

by many investigators since the 1970s (Gilboa et al. 1976);

however, the number of studies drastically increased after

the GEF (Global Environment Fund)-funded Guarani

Aquifer Program for Groundwater Resource Sustainability

and Environmental Protection which was valued at US$

26.7 million with 50 % from GEF (Foster et al. 2006). As a

consequence of this international support, hydrochemical,

stable isotopes (hydrogen, oxygen, carbon) and 14C data

have been obtained, allowing, among others aspects: (a) to

establish the groundwater flow pattern in the northern

A. Soler i Gil

Grup de Mineralogia Aplicada i Medi Ambient, Facultat de

Geologia, Universitat de Barcelona, c/Martı i Franques s/n,

08028 Barcelona, Spain

D. M. Bonotto (&)

Instituto de Geociencias e Ciencias Exatas-IGCE, Universidade

Estadual Paulista-UNESP, Av. 24-A No. 1515,

P.O. Box 178, Rio Claro, Sao Paulo CEP 13506-900, Brazil

e-mail: danielbonotto@yahoo.com.br

123

Environ Earth Sci

DOI 10.1007/s12665-014-3397-0

portion of GAS that is characterized by the existence of

four regional recharge areas located in Sao Paulo, Mato

Grosso do Sul and Goias States in Brazil (Gastmans et al.

2010b); (b) to define the paleoclimatic conditions in the

regional recharge areas of the western part of the GAS in

Brazil; (c) to propose a conceptual geochemical model of

the GAS, suggesting dissolution of calcite driven by cation

exchange, which occurs at a relatively narrow front in Sao

Paulo State recently moving downgradient at much slower

rate compared to groundwater flow (Hirata et al. 2011).

In addition to these studies, there have been various

reports documented in radiometric investigations in GAS

groundwaters (Bonotto and Caprioglio 2002; Bonotto

2004, 2006, 2011; Bonotto and Mello 2006; Bonotto and

Bueno 2008; Bonotto and Armada 2008; Bonotto et al.

2009a, b). This paper reports novel hydrochemical (major

and trace elements) and stable isotopes (H, O, S) data in

rainwater and GAS groundwater. The authors have inter-

preted them according to the water temperature based on

the classification criterion established by the Brazilian

Code of Mineral Waters (BCMW) with the main purpose

of revealing the occurrence of important processes affect-

ing the GAS. Secondarily, this new database contributes to

show a scenario different of that generated from previous

studies in which more negative d18O values have been

proposed to accompany the groundwater flow direction in

Sao Paulo State.

Study area

The Parana sedimentary basin constitutes a geotectonic

unit established over the South American Platform since

the Lower Devonian or Silurian (Almeida and Melo 1981).

It is located between parallels 10�–20� southern latitude

and meridians 47�–64� western longitude, comprising

southern Brazil (states of Mato Grosso, Mato Grosso do

Sul, Goias, Minas Gerais, Sao Paulo, Parana, Santa Cata-

rina and Rio Grande do Sul), eastern Paraguay, NW Uru-

guay and the northeastern extreme corner of Argentina.

The accentuated basin subsidence allowed an accumulation

of thick sediments layers, basaltic lavas and diabase sills,

whose total thickness in its deepest portion reached up to

5 km (Gilboa et al. 1976).

The major stratigraphic units in the basin are (Soares

1975, Almeida and Melo 1981): Tubarao Group (Permian-

Carboniferous), comprising the Itarare Formation (sand-

stones, conglomerates, diamictites, tillites, siltstones,

shales and rythmites) and Tatuı Formation (siltstones,

shales, silex and sandstones with local concretions); Passa

Dois Group (Upper Permian), mainly represented by Irati

Formation (siltstones, mudstones, black betuminous shales

and limestones) and Corumbataı Formation (mudstones,

shales and siltstones); Sao Bento Group (Lower Triassic–

Cretaceous), comprising the Piramboia Formation (sand-

stones, shales and muddy sandstones), Botucatu Formation

(sandstones and muddy sandstones), Serra Geral Formation

(basalts and diabases) and related basic intrusives; Bauru

Group (Upper Cretaceous), consisting on continental si-

liciclastic sediments; different types of Cenozoic covers

like the recent deposits, terrace sediments and the Rio

Claro Formation (sandstones, conglomerate sandstones and

muddy sandstones). The names of the Botucatu and Pira-

mboia formations were adopted in 1899 by geologists of

the Sao Paulo Geographical and Geological Commission in

Sao Paulo State for designating sandstones occurring at

Botucatu and Piramboia cities that are *30 km distant

(Fig. 1) (Almeida and Melo 1981).

Multiaquifer systems mainly comprising sandstones

and basalts plus sediments from the Passa Dois Group

behaving as aquitards have been proposed to represent the

hydrostratigraphy of the Parana basin (Campos 2000).

Groundwater occurs within the interflow zones and along

cooling joints in basalts and diabases from the Serra Geral

Formation. The sandstones of Cretaceous age (Bauru

Group) are moderately cemented and exhibit adequate

properties to store water. The Paleozoic sediments also

provide highly mineralized water in the central parts of

the basin as evidenced from the concentrations of Na?,

Cl- and SO42- values of 25,000, 35,000 and 9,000 mg/L,

respectively, in samples provided from oil wells drilled

during petroleum exploration in the Parana basin (Meng

and Maynard 2001). In Brazil, the GAS comprises the

Piramboia/Rosario do Sul/Botucatu formations that have

an average thickness of 300–400 m (Araujo et al. 1999).

The GAS is confined by thick basaltic packages of the

Serra Geral Formation (up to 1,500 m), overlying previ-

ous formations ranging from the igneous basement to the

Paleozoic sediments of the Passa Dois and Tubarao

Groups. The percolating water moves from the phreatic

exposed areas that surround the entire basin towards its

central part.

The confining layers of the Serra Geral Formation

overlying the GAS was verified in all wells sampled in this

study along transect AA’ (Fig. 2), inclusive those drilled at

Aracatuba and Tres Lagoas cities (Fig. 1). The lithology

description of the bores exploiting Tubarao Aquifer indi-

cated that they did not intercept the Serra Geral Formation

and that the Piramboia Formation overlies greatly variable

thick layers of the Passa Dois and Tubarao Group sedi-

ments. The thickness of the Passa Dois Group sediments

layer at Rio Claro city was *30 m that is much lower than

150–200 m verified at Aguas de Sao Pedro city. The Tu-

barao Group sediments layer at Rio Claro city was also

thinner (*120 m) than that occurring at Aguas de Sao

Pedro city (230–350 m).

Environ Earth Sci

123

Sampling and analytical methods

Rainwater and groundwater samples in this study were

collected in the Brazilian states of Sao Paulo, Minas Gerais

and Mato Grosso do Sul (Fig. 1). Five sites were selected

for rainwater sampling from the rainfall station BOT at

Botucatu city: two at the GAS recharge beds (RCL-RW:

Rio Claro city; SPO: Sao Pedro city) and three progres-

sively distant of them (ASB: Aguas de Santa Barbara city;

ASI: Assis city; PPE-RW: Presidente Prudente city)

(Fig. 1).

The rainfall samples for chemical and isotopes analyses

were obtained during field campaigns held at the wet sea-

son end (February–March 2010), ensuring collection of

pristine rainfall samples. The precipitation samples (6)

were collected with bulk (dry and wet deposition) collec-

tors consisting of large rectangular funnels coupled to

polyethylene bottles that allowed rapidly sampling almost

the same rainfall events, without the need of specific pro-

tocol for collections performed over long periods of time

(Pelicho et al. 2006).

The flasks filled with rainwater were removed and

transported up to LABIDRO-Isotopes and Hydrochemistry

Laboratory of UNESP at Rio Claro city. The pH and

conductivity were in situ measured, whereas aliquots were

separated for evaluating the suspended solids and preserved

with HNO3 or H2SO4 for obtaining the following compo-

sition data: Na and K by atomic absorption spectrometry;

PO43- by FIA-flow injection analysis; Ca, Mg,

CO32-?HCO3

-, Cl-, Br-, SO42-, NO3

-, Al, Li, Be, Ba,

Fig. 1 A simplified map

modified from Silva (1983)

showing the sampling points,

the outcrop and groundwater

flow direction in the GAS, Sao

Paulo State, Brazil. The transect

AA’ from Avare up to

Presidente Epitacio (SE–NW

direction) is also shown. City

codes: AVR Avare; SUT

Sarutaia; ASB Aguas de Santa

Barbara; BCS Bernardino de

Campos; ASI Assis; PPA

Paraguacu Paulista; PPE

Presidente Prudente; PEO

Presidente Epitacio; BOT

Botucatu; SPO Sao Pedro; ASP

Aguas de Sao Pedro; SMS Santa

Maria da Serra; PIC Piracicaba;

RCL Rio Claro; CAM

Campinas; ATA Aracatuba; TLG

Tres Lagoas; SLO Sao Carlos;

RPT Ribeirao Preto; BRP

Braganca Paulista; SAO Sao

Paulo; ADP Aguas da Prata;

PCS Pocos de Caldas; AXA

Araxa

Environ Earth Sci

123

V, Mo, Cr, Mn, Co, Ni, Cu, Zn, Pb, Cd, Tl, As, Sb, Se, Rb,

Sr by ICP-MS.

The precipitation sampling and storage for 2H (D) and18O measurements followed the general guidelines pro-

posed by Clark and Fritz (1997) and Mook (2000), where,

after initial processing, the samples were subject to mass

spectrometry for d18O and dD readings. The results were

expressed in parts per mil (%) relative to the 18O/16O and

D/H ratios of Vienna Standard Mean Ocean Water

(VSMOW), as determined by the equations:

d18Owater ¼ f½ð18O=16

OÞsample=ð18

O=16OÞVSMOW� � 1g

� 1; 000

ð1Þ

dD ¼ f½ð2H=1HÞsample=ð

2H=1

HÞVSMOW� � 1g � 1; 000

ð2Þ

The GAS groundwater samples (6) were initially collected

along one transect in Sao Paulo State that had been already

focused in previous investigations (Sracek and Hirata 2002;

Bonotto 2006; Cresswell and Bonotto 2008) (Figs. 1, 2):

AVR—Avare city; SUT—Sarutaia city; BCS—Bernardino

de Campos city; PPA—Paraguacu Paulista city; PPE-

GW—Presidente Prudente city; PEO—Presidente Epitacio

city. Five additional samples were also collected and ana-

lyzed, two provided from deep tubular wells drilled at the

GAS confined portions (ATA Aracatuba city; TLG Tres

Lagoas city) and three coming from bores exploiting Tu-

barao Aquifer at the GAS recharge beds (RCL-GW Rio

Claro city; ASP-GIO Aguas de Sao Pedro city; ASP-JUV

Aguas de Sao Pedro city) (Fig. 1).

The groundwater samples were stored in polyethylene

bottles and subjected to in situ temperature, dissolved

oxygen, pH, Eh (redox potential) and conductivity readings

as reported by Bonotto (2006). Diagrams and nomographs

involving the equilibria of carbonates and water (APHA

1989) enabled evaluation of the free dissolved CO2. Silica

was determined by colorimetry (Hach 1992), fluoride by

ion-selective electrode and the same techniques adopted for

the rainfall samples were utilized for characterizing the

major/trace elements/ions and stable isotopes 2H and 18O.

Groundwater samples from the GAS deeper portions

along transect AA’ and from deep tubular wells were also

analyzed for d18Osulfate and d34S. Each aliquot was acidi-

fied with HCl and a barium chloride solution was added in

excess to variable sample volume for precipitating an

expected amount of around 50 mg of BaSO4. The precip-

itation was held at *100 �C to prevent the BaCO3 for-

mation. The hot solution rested 1–3 days for settling the

precipitate that was filtered through a 3-lm paper filter,

dried at room temperature (7–10 days) and inserted into a

Schott glass vial. d34S-SO42- was analyzed in a Carlo Erba

Elemental Analyzer (EA) coupled in continuous flow to a

Finnigan Delta C IRMS. d18O-SO42- was analyzed in

duplicate with a ThermoQuest TC/EA unit (high-temper-

ature conversion elemental analyzer) with a Finnigan Matt

Delta C IRMS. The d18Osulfate and d34S data (in %) were

determined by the equations:

d18Osulfate ¼ f½ð18O=16

OÞsample=ð18

O=16OÞSMOV� � 1g

� 1; 000

ð3Þ

d34S ¼ f½ð34S=32

SÞsample=ð34

S=32SÞCDT� � 1g � 1; 000

ð4Þ

where (34S/32S)CDT is the 34S/32S ratio (0.0450) in

troilite (FeS) of the iron meteorite Canyon Diablo and

(18O/16O)SMOV the isotopic ratio of Vienna Standard

Fig. 2 Simplified geological

cross-section along transect

AA’ showing the depth and

lithology of the bores, as well

the direction of the groundwater

flow in the GAS. Adapted from

Silva (1983)

Environ Earth Sci

123

Mean Ocean Water standard. Accuracy of isotope

analysis was daily verified by measurements of inter-

national and internal standards characterized against

international reference materials. Reproducibility (1r)

of the samples was determined as follows: ±0.2 % for

d34S-SO42- and ±0.5 % for d18O-SO4

2-. This

methodological approach was also applied to spring

waters occurring at Pocos de Caldas and Araxa cities,

Minas Gerais State, Brazil, which exhibit enhanced

dissolved sulfate levels but whose discharge is through

cracks, faults and joints in rock types different of those

occurring in Parana basin.

Table 1 Composition of rainwater in selected sampling sites in Sao Paulo State, Brazil

Parameter (unit) Rio Claro Sao Pedro Botucatu Aguas de

Santa Barbara

Assis Presidente

Prudente

Average

Station code RCL-RW SPO BOT ASB ASI PPE-RW –

Latitude 22�220S 22�320S 22�560S 22�380S 22�530S 22�060S –

Longitude 47�360W 47�550W 48�180W 50�240W 49�140W 51�230W –

Altitude (m a.s.l.) 625 550 804 644 546 475 –

pH 5.90 6.50 6.20 6.60 6.20 6.20 6.27

Conductivity (lS/cm) 110 120 100 110 100 100 110

Total dissolved solids (mg/L) 15.13 17.98 8.01 11.83 4.97 7.11 10.84

Sodium (mg/L) 0.88 0.75 0.21 0.56 0.17 0.32 0.48

Potassium (mg/L) 0.30 1.08 0.25 0.49 0.13 0.14 0.40

Calcium (mg/L) 0.83 1.65 0.42 1.07 0.31 0.45 0.79

Magnesium (mg/L) 0.25 0.40 0.08 0.18 0.07 0.13 0.18

Bicarbonate ? carbonate (mg/L) 7.00 7.00 3.00 6.00 3.00 4.00 5.00

Chloride (mg/L) 1.11 0.87 1.76 0.97 0.53 0.68 0.99

Bromide (mg/L) 0.01 0.02 0.03 0.01 0.01 0.01 0.02

Sulfate (mg/L) 1.16 1.34 0.27 1.00 0.30 0.51 0.76

Nitrate (mg/L) 3.54 4.82 1.96 1.51 0.40 0.82 2.18

Phosphate (mg/L) \0.10 \0.10 \0.10 \0.10 \0.10 \0.10 \0.10

Aluminum (lg/L) 17.80 3.93 7.89 4.23 3.10 3.98 6.82

Lithium (lg/L) 0.12 0.23 0.03 0.07 0.04 0.16 0.11

Beryllium (lg/L) 0.01 0.01 0.02 0.01 \0.001 0.01 0.01

Barium (lg/L) 3.14 5.05 3.36 8.15 2.93 8.70 5.22

Vanadium (lg/L) 0.33 0.50 0.18 0.22 0.21 0.13 0.26

Molybdenum (lg/L) 0.90 0.38 0.41 0.58 0.33 0.34 0.49

Chromium (lg/L) 0.40 0.35 0.69 0.60 0.39 1.95 0.73

Manganese (lg/L) 2.55 5.63 1.73 4.35 2.54 5.34 3.69

Cobalt (lg/L) 0.11 0.09 0.10 0.12 0.10 0.20 0.12

Nickel (lg/L) 1.10 1.08 1.42 1.86 1.99 10.96 3.07

Copper (lg/L) 9.17 4.60 2.25 3.87 1.48 3.11 4.08

Zinc (lg/L) 0.09 12.02 3.71 6.43 33.20 8.11 10.59

Lead (lg/L) 0.85 0.27 0.86 0.91 0.90 0.86 0.78

Cadmium (lg/L) 0.01 0.05 0.04 0.24 0.08 0.04 0.08

Thallium (lg/L) 0.02 0.03 0.02 0.02 0.02 0.02 0.02

Arsenic (lg/L) 0.24 0.96 0.15 0.20 0.15 0.13 0.30

Antimony (lg/L) 0.17 0.39 0.15 0.24 0.27 0.16 0.23

Selenium (lg/L) 0.07 0.07 0.03 \0.01 \0.01 \0.01 0.03

Rubidium (lg/L) 1.21 1.69 0.43 0.91 0.25 0.28 0.80

Strontium (lg/L) 4.07 7.11 3.74 5.00 2.00 3.15 4.18

dD (%) -48.5 -30.9 -122.4 -73.3 -111.7 -97.0 –

d18Owater (%) -6.6 -4.0 -16.8 -10.1 -14.4 -13.6 –

Environ Earth Sci

123

Table 2 Composition of groundwater along transect AA’

Parameter (unit) Avare Sarutaia Bernardino

de Campos

Paraguacu

Paulista

Presidente

Prudente

Presidente

Epitacio

Sample code AVR SUT BCS PPA PPE-GW PEO

Latitude 23�0604600S 23�1600300S 23�0104100S 22�2502100S 22�0604500S 21�4602900S

Longitude 48�5403300W 49�2900500W 49�2900500W 50�3303800W 51�2204300W 52�0502700W

Altitude (m a.s.l.) 640 750 660 474 407 258

Distance from Botucatu

city (km)

56 117 109 214 300 376

Depth (m) 150 152 509 3,663 1,800 3,953

Lithology M-BA-SG-BP M-SG-BO-DI M-SG-BO-PI BA-SG-BO-PD-TU-PA BA-SG-BO-PI-PD BA-SG-BO

Geostatic pressure (bar) 10.2 7.8 87.4 258.7 382.0 430.4

Temperature (�C) 23 23 28 43 63 70

Dissolved O2 (mg/L) 6.0 8.0 7.0 3.2 2.4 2.8

Dissolved CO2 (latm) 99,466 16,578 25,286 59 314 384

pH 5.9 6.4 6.6 9.6 8.8 8.7

Eh (mV) 144 164 200 -66 -55 -72

Conductivity (lS/cm) 190 180 290 730 1,340 1,030

Sodium (mg/L) 3.34 5.05 17.75 125.9 208.4 170.2

Potassium (mg/L) 1.74 0.87 1.2 0.83 3.01 1.55

Calcium (mg/L) 9.83 8.56 20.58 1.20 7.12 2.86

Magnesium (mg/L) 3.82 1.11 0.77 \0.01 0.45 0.03

Carbonate ? bicarbonate

(mg/L)

63 53 120 337 327 170

Chloride (mg/L) 0.65 0.49 0.63 9.36 102.90 24.60

Bromide (mg/L) 0.02 0.01 0.01 0.04 0.17 0.06

Sulfate (mg/L) 0.22 0.39 0.34 10.89 79.27 40.31

Nitrate (mg/L) 0.11 0.84 0.74 0.12 0.41 0.81

Phosphate (mg/L) 0.41 0.35 \0.10 \0.10 \0.10 \0.10

Fluoride (mg/L) 0.02 0.05 0.02 1.6 8.8 6.6

Silica (mg/L) 49.0 39.0 37.0 49.0 32.0 35.7

Total dissolved solids (mg/L) 131.9 109.5 199.2 524.2 771.9 453.8

Aluminum (lg/L) 3.44 3.00 5.92 78.06 58.42 71.67

Lithium (lg/L) 0.90 2.02 2.97 19.78 57.35 29.48

Beryllium (lg/L) 0.003 \0.001 0.020 \0.001 0.017 \0.001

Barium (lg/L) 16.55 11.48 10.86 0.15 29.33 12.89

Molybdenum (lg/L) \0.01 \0.01 0.02 0.65 4.60 3.59

Chromium (lg/L) 0.979 1.391 2.053 3.534 15.580 2.268

Manganese (lg/L) 0.102 0.157 0.229 0.473 2.065 0.634

Cobalt (lg/L) 0.011 0.017 0.027 0.070 0.079 0.162

Zinc (lg/L) 2.16 6.55 0.63 22.83 – 4.90

Lead (lg/L) 0.179 0.473 0.119 0.095 – 0.355

Cadmium (lg/L) 0.16 0.01 0.01 0.02 \0.01 0.05

Arsenic (lg/L) 0.03 0.44 0.10 19.62 4.73 6.95

Selenium (lg/L) \0.01 0.16 0.66 0.79 2.94 0.53

Rubidium (lg/L) 3.14 5.00 1.05 0.81 5.32 1.31

Strontium (lg/L) 98.67 83.07 146.76 5.54 143.97 69.14

dD (%) -52.4a -46.4 -40.9 -50.8 -49.0 -48.0

d18Owater (%) -7.92 -7.3 -6.9 -6.9 -7.0 -7.1

d34S (%) – – – ?2.0 ?6.6 ?6.1

Environ Earth Sci

123

Results and discussion

Groundwater quality

The results of the analysis are given in Tables 1, 2, 3 and

4. WHO (2011) established guideline values for the fol-

lowing chemicals that are of health significance in

drinking water: nitrate (50 mg/L), barium (700 lg/L),

chromium (50 lg/L), lead (10 lg/L), cadmium (3 lg/L),

arsenic (10 lg/L), selenium (40 lg/L) and fluoride

(1.5 mg/L). Table 2 reports its content in groundwater

samples collected along transect AA’ (Fig. 2), which

exceeded the maximum allowable for fluoride in hyper-

thermal waters PPA, PPE-GW and PEO, as well for

arsenic in groundwater sample PPA. However, none of

these waters is used for human consumption, only in

thermal swimming pools. The enhanced fluoride concen-

tration in GAS groundwater is a situation already identi-

fied in previous studies (Kimmelmann e Silva et al. 1989;

Bonotto 2006) and anomalous arsenic contents have also

Table 2 continued

Parameter (unit) Avare Sarutaia Bernardino

de Campos

Paraguacu

Paulista

Presidente

Prudente

Presidente

Epitacio

d18Osulfate (%) – – – ?14.1 ?15.5 ?14.9

M weathered mantle; DI diabase sill; BA Bauru Group; SG Serra Geral Formation; BO Botucatu Formation; PI Piramboia Formation; BP

Undifferentiated Botucatu-Piramboia Formations; PD Passa Dois Group; TU Tubarao Group; PA Parana Groupa Mean value of three analyses reported by Kimmelmann et al. (1995)

Table 3 Composition of

groundwater in deep tube wells

of Parana Sedimentary Basin,

Brazil

M weathered mantle, BA Bauru

Group, SG Serra Geral

Formation, PI Piramboia

Formation, BP Undifferentiated

Botucatu-Piramboia

Formations, PD Passa Dois

Group, TU Tubarao Group

Parameter (unit) Aracatuba Tres Lagoas Aguas de

Sao Pedro

Aguas de

Sao Pedro

Rio Claro

Sample code ATA TLG ASP-GIO ASP-JUV RCL-GW

Latitude 21�1204000S 20�4701900S 22�3503000S 22�3503000S 22�2403000S

Longitude 50�2602100W 51�4104900W 47�5303800W 47�5303800W 47�2900500W

Altitude (m a.s.l.) 410 315 530 530 560

Depth (m) 1,300 4,582 625 469 199

Lithology BA-SG-BP SG-BP M-PI-PD-

TU

M-PI-PD-

TU

M-PI-PD-

TU

Temperature (�C) 42 46 23 25 22

Dissolved O2 (mg/L) 3.5 2.3 6.2 4.5 3.6

pH 9.4 9.0 6.4 8.7 9.2

Eh (mV) -57 67 62 -304 -41

Conductivity (lS/cm) 420 760 3,290 3,850 –

Sodium (mg/L) 102 165 590 670 117.6

Potassium (mg/L) 0.47 0.06 2.3 2.9 0.6

Calcium (mg/L) 0.9 1.09 0.1 1 0.2

Magnesium (mg/L) 0.1 0.1 0.8 0.1 0.2

Carbonate ? bicarbonate

(mg/L)

170 176 23 47 215

Chloride (mg/L) 23 84 568 1,041.2 5.2

Sulfate (mg/L) 22.9 65.2 300 140 43.7

Nitrate (mg/L) 0.6 0.5 0.06 0.01 0.01

Fluoride (mg/L) 0.64 1.45 22.97 27.72 1.34

Silica (mg/L) 26 23 13.7 18.9 7.8

Total dissolved solids (mg/L) 346.6 516.4 1,520.9 1,948.8 391.6

dD (%) -56.2 -44.1 -35.5 -31.7 -55.6

d18Owater (%) -8.6 -6.9 -5.7 -5.3 -8.3

d34S (%) ?7.7 ?9.0 ?23.6 ?26.9 ?9.5

d18Osulfate (%) ?15.9 ?14.4 ?16.9 ?12.6 ?13.9

Environ Earth Sci

123

been reported by Gastmans et al. (2010c) at the Thermal

Corridor of Uruguay River located in the triple border of

Argentina, Brazil and Uruguay. Gastmans et al. (2010c)

described iron oxide coatings in sandstones of Buena

Vista and Sanga do Cabral formations, which underlie

GAS units, proposing that arsenic is released to ground-

water by desorption from iron oxides/hydroxides, as a

result of the higher pH of the waters.

Groundwater temperature and major hydrochemical

trends

The Brazilian Code of Mineral Waters (BCMW) was

established by Register 7841 published on 8 August 1945

(DFPM 1966). According to temperature, the waters may

be classified as follows: cold—values lower than 25 �C;

hypothermal—values ranging from 25 to 33 �C; meso-

thermal—values ranging from 33 to 36 �C; isothermal—

values between 36 and 38 �C; hyperthermal—values

higher than 38 �C. The groundwaters along transect AA’

(Fig. 1) are not ruled out by the BCMW, but they are used

for human consumption and recreation purposes like in

thermal swimming pools. Thus, the BCMW temperature

guidelines are useful for classifying them and three cate-

gories may be defined (Table 2): cold—samples AVR and

SUT; hypothermal—sample BCS; hyperthermal—samples

PPA, PPE-GW and PEO. The groundwater samples ATA

and TLG provided from deep wells are also hyperthermal,

whereas the samples ASP-GIO, ASP-JUV and RCL-GW

coming from bores exploiting Tubarao Aquifer are cold/

hypothermal (Table 3).

The occurrence of waters at elevated temperatures

(above 40 �C) has been identified in GAS as a consequence

of the great depths reached by the aquifer (almost 2 km)

and thick confining basaltic cover (Teissedre and Barner

1981; Silva 1983; Bonotto 2006). The groundwater tem-

perature is related to the groundwater flow from the border

of the basin towards its central part, in the direction of the

Table 4 Composition of spring

water from Pocos de Caldas

plateau and alkaline carbonatitic

complex of Araxa, Minas Gerais

State, Brazil

Hydrochemical data reported by

Cruz (1987), Cruz and Peixoto

(1989), Mancini (2002) and

Bonotto (2005)a Lithology: alkaline volcanic

and plutonic rocks, mainly

phonolites and nepheline

syenitesb Lithology: alkaline rocks

(carbonatite), mica-rich rocks,

phoscorites and lamprophyres

Parameter (unit) Macacosa Quisisanaa

Sulfurosa

Sinhazinhab Andrade

Juniorb

City Pocos de Caldas Pocos de Caldas Pocos de Caldas Araxa

Sample code PCS-MAC PCS-QSA PCS-SIN AXA

Latitude 21�4603300S 21�4603300S 21�4603300S 19�3804900S

Longitude 46�3604200W 46�3604200W 46�3604200W 46�5605700W

Altitude (m a.s.l.) 1,186 1,186 1,186 973

Temperature (�C) 37 27 23 31

Dissolved O2 (mg/L) 1.8 7.2 2.0 –

pH 9.8 9.5 9.6 10.0

Eh (mV) -150 -251 -310 -32

Conductivity (lS/cm) 1,010 505 830 6,530

Sodium (mg/L) 214.9 137.9 217.5 124.1

Potassium (mg/L) 7.2 5.0 6.0 3.1

Calcium (mg/L) 1.2 2.6 4.2 0.3

Magnesium (mg/L) 0.1 0.5 0.6 0.02

Barium (lg/L) 43 43 61 1,000

Carbonate ? bicarbonate (mg/L) 300.2 222.2 292.3 804.0

Chloride (mg/L) 4.0 2.6 4.3 9.5

Sulfate (mg/L) 62.5 43.1 77.0 220.0

Fluoride (mg/L) 24.8 17.0 33.1 11.2

Total dissolved solids (mg/L) 579 398 574 1,182

dD (%) -63.8 -58.2 -53.7 -64.0

d18Owater (%) -9.7 -9.0 -7.8 -14.1

d34S (%) ?7.3 ?6.6 ?8.3 ?5.0

d18Osulfate (%) ?6.0 ?7.2 ?6.7 ?8.1

Saturation index (SI)

Anhydrite -4.08 -3.70 -3.39 -4.41

Gypsum -3.92 -3.49 -3.16 -4.22

Barite -0.51 -0.38 -0.001 ?1.30

Environ Earth Sci

123

dip of the geological units, according to the natural geo-

thermal gradient of about 1 �C for each 35 m depth. Fig-

ure 3 shows the groundwater temperature and other

parameters plotted against the distance to the recharge beds

situated at Botucatu city. Two major groups can be iden-

tified (Table 2): cold/hypothermal—groundwater samples

AVR, SUT and BCS; hyperthermal—groundwater samples

PPA, PPE-GW and PEO.

Bonotto (2006) estimated the geostatic (lithostatic)

pressure, P, in GAS from the equation (Castany 1982):

P = Pa ? qgh (Pa atmospheric pressure, q average strata

density, g gravity acceleration, h depth of the aquifer top).

The hyperthermal waters exhibited pressures higher than

250 bars, whereas the cold/hypothermal waters exhibited

values lower than 100 bars (Fig. 3).

Additional trends of the hydrochemical data are also

related to temperature, for instance, the cold/hypother-

mal waters exhibited higher values of dissolved oxy-

gen, free CO2, redox potential Eh and lower values of

pH, conductivity and TDS relative to the hyperthermal

ones (Fig. 3). Major ions like sodium, chloride, sulfate

and (bi)carbonate were enhanced in the hyperthermal

waters relative to the cold/hypothermal ones, whilst

calcium and magnesium were higher in the cold/

hypothermal waters (Fig. 4), possibly related to the fact

that the carbonate mineral reactivity in aqueous solu-

tion tends to decrease at higher temperatures and partial

CO2 pressure (Faure 1991; Bonotto 2006; Pokrovsky

et al. 2009). There is a significant correlation of the

dissolved strontium content with Ca (r = 0.75) and Ba

(r = 0.76) in the samples collected along transect AA’.

The Sr and Ba contents are plotted in Fig. 5 against the

recharge beds distance, indicating an accentuated con-

centration decrease in PPA hyperthermal waters, as

well verified for Ca (Fig. 4).

Neither potassium nor nitrate and silica exhibited similar

trends when plotted against the recharge beds distance

(Fig. 4). The desorption of layers of adsorbed water mol-

ecules from clays is a function of the burial depth in sed-

iments that is directly related to the geostatic/lithostatic

pressure, i.e. the number of adsorbed water layers decrea-

ses according to the temperature and pressure increase

(Velde 1992). Thus, desorption processes affecting clay

minerals and occurring at higher temperatures verified

along transect AA’ could justify the enhanced concentra-

tions of the trace elements Al, Li, F, Br, Co, Mn, As and

Mo in the hyperthermal waters relative to the cold/hypo-

thermal ones (Fig. 5).

Fig. 3 The geostatic pressure, temperature, dissolved oxygen, dis-

solved CO2, pH, redox potential Eh, conductivity and TDS (Total

Dissolved Solids) of cold/hypothermal waters (diamonds) and

hyperthermal waters (squares) along transect AA’ plotted against

the recharge beds distance (starting point Botucatu city)

Environ Earth Sci

123

Hydrochemistry in the cold/hypothermal waters

Figure 6 shows the major chemistry, in mEq/L, of the cold

waters AVR/SUT and hypothermal water BCS plotted in a

Schoeller (1962) diagram together with the average values

obtained for the main ions in rainfall (Table 1). These

groundwaters are exploited from wells drilled closer to the

recharge beds. They exhibit TDS values *10–18 times

higher than in rainwater, as well the following enrichments

(molar ratios) in major ions as a consequence of the water–

soil/rock interactions: Na? (6.9–36.8), K? (2.2–4.4), Ca2?

(10.8–26.1), Mg2? (4.2–20.6) and HCO3- ? CO3

2-

(10.6–24.0).

There is a significant correlation among all major dis-

solved ions in groundwater and rainwater: AVR, r = 0.85;

SUT, r = 0.91; BCS, r = 0.90. This indicates strong

influence of the rainwater composition in the groundwater

chemistry closer to the recharge beds; thus, when one ion

concentration is higher relatively to another in rainwater,

the same occurs in groundwater, as shown in Fig. 6.

However, there is no significant correlation among all

trace elements analyzed in groundwater and rainwater:

AVR, r = 0.24; SUT, r = 0.20; BCS, r = 0.13. This

indicates dissolution, adsorption, precipitation, exchange,

complexing, oxidation, reduction or biological reactions

taking place at the aquifer strata during the groundwater

flow. But all trace elements’ concentration in the cold/

hypothermal waters exhibited significant correlation: AVR

and SUT, r = 0.99; AVR and BCS, r = 0.99; SUT and

BCS, r = 0.99. All they are Ca2? - HCO3- ? CO3

2-

dominated waters (Fig. 6) occurring in slightly acidic to

neutral pH conditions and transitional to reducing redox

potentials (Fig. 7).

Hydrochemistry in the hyperthermal waters

Figure 8 shows the major chemistry, in mEq/L, of the hy-

perthermal waters PPA, PPE-GW and PEO plotted in a

Schoeller (1962) diagram together with the data obtained

for the main dissolved ions in groundwater samples ATA,

TLG, ASP-GIO, ASP-JUV, and RCL-GW (Table 3). The

hyperthermal waters PPA, PPE-GW and PEO are exploited

from deep (1,800–3,900 m) wells originally drilled for oil

exploration in Parana sedimentary basin. They exhibit TDS

values circa 42–71 times higher than in rainwater, as well

the following enrichments (molar ratios) in major ions: Na?

(261–433), K? (2.1–7.6), Ca2? (1.5–9.0), HCO3- ? CO3

2-

(34–67), Cl- (9–104) and SO42- (14–104).

Fig. 4 The dissolved sodium, chloride, sulfate (bi)carbonate, calcium, magnesium, potassium, nitrate and silica of cold/hypothermal waters

(diamonds) and hyperthermal waters (squares) along transect AA’ plotted against the recharge beds distance (starting point Botucatu city)

Environ Earth Sci

123

There is no significant correlation among all major

dissolved ions in hyperthermal waters and rainwater: PPA,

r = 0.64; PPE-GW, r = 0.35; PEO, r = 0.22; ATA,

r = 0.54; TLG, r = 0.27. Also, non-significant correlation

was found among all trace elements analyzed in them:

PPA, r = 0.18; PPE-GW, r = 0.14; PEO, r = 0.10. Both

findings suggest little/weak influence of the rainwater

composition in the hyperthermal waters chemistry.

Contrarily, significant correlation was found among the

major ion contents in the hyperthermal waters: PPA and

PPE-GW, r = 0.91; PPA and PEO, r = 0.86; PPE-GW and

PEO, r = 0.96; PPA and ATA, r = 0.99; PPA and TLG,

r = 0.87; PPE-GW and ATA, r = 0.96; PPE-GW and TLG,

r = 1.0; PEO and ATA, r = 0.92; PEO and TLG, r = 0.97.

Significant correlation among the trace elements content

was found too between PPA and PPE-GW (r = 0.97), PPA

and PEO (r = 0.98), PPE-GW and PEO (r = 1.0).

The major ion enrichments to rainwater in hyperthermal

waters PPA, PPE-GW and PEO were very different of that

in the cold/hypothermal waters AVR, SUT and BCS:

higher sodium enrichment was found in hyperthermal

waters relative to the cold/hypothermal ones; chloride and

sulfate were enriched in hyperthermal waters, but not in the

cold/hypothermal ones; magnesium was impoverished in

hyperthermal waters PPA and PEO, as the molar ratio

relative to rainwater was 0.05 and 0.16, respectively. The

carbonates reactivity decrease in aqueous solution accord-

ing to the temperature rising could justify this impover-

ishment (Pokrovsky et al. 2009).

The groundwater samples ATA and TLG are also hy-

perthermal, and exhibit basic pH and transitional to

reducing redox potentials (Fig. 7), which correspond to the

same characteristics of the samples PPA, PPE-GW and

PEO in transect AA’. They have been exploited from deep

(1,300–4,600 m) wells drilled for oil exploration, pos-

sessing TDS contents about 32–48 times higher than in

rainwater and exhibiting the following enrichment (molar

ratio) to rainwater: Na? (212–342), Ca2? (1.1–1.4),

HCO3- ?CO3

2- (34–35), Cl- (23–85) and SO42- (30–85).

Thus, there is a dominant presence of sodium, chloride and

sulfate as in the hyperthermal waters sampled along tran-

sect AA’. The similarity exists inclusive to the Mg2?

impoverishment relative to rainwater as the molar ratio is

0.5 in waters ATA and TLG.

The cold/hypothermal waters with high TDS contents

The groundwaters ASP-GIO, ASP-JUV and RCL-GW in

Table 3 are cold/hypothermal, and exhibit pH basic (ASP-

JUV, RCL-GW) or acid (ASP-GIO) and reducing character

Fig. 5 The dissolved aluminum, lithium, fluoride, bromide, cobalt, manganese, arsenic, molybdenum, strontium and barium of cold/hypothermal

waters (diamonds) and hyperthermal waters (squares) along transect AA’ plotted against the recharge beds distance (starting point Botucatu city)

Environ Earth Sci

123

(Fig. 7). Their TDS content is about 36–180 times higher

than in rainwater; thus, these characteristics are not exactly

the same of the hyperthermal waters PPA, PPE-GW and

PEO in transect AA’. The sample RCL-GW exhibits

enrichment (molar ratio) to rainwater practically within the

range of the values found for groundwaters PPA, PPE-GW

and PEO: Na? (244), HCO3- ?CO3

2- (43), Cl- (5.3) and

SO42- (57). However, much higher molar ratio to rainwater

was found for waters ASP-JUV and ASP-GIO: Na?

(1,225–1,391), Cl- (576–1,055) and SO42- (183–393).

The composition of the hyperthermal waters PPA, PPE-

GW, PEO, ATA, TLG and cold groundwater RCL-GW is

dominated by major ions sodium and (bi)carbonate,

whereas the groundwater samples ASP-JUV and ASP-GIO

are Na?–Cl- dominated. The Cl--dominated groundwaters

ASP-GIO and ASP-JUV exhibit Na?/Cl- molar ratios

corresponding to 1.6 and 0.99, respectively, tending to

reach the seawater value of 0.85 (Pinet 2006). The Na?/

Cl- ratios progressively depart of the seawater in the

(bi)carbonate-dominated waters, corresponding to values

from 3.0 to 20.7 in the hyperthermal waters PPA, PPE-GW,

PEO, ATA and TLG and from 7.9 to 43.4 in the cold/

hypothermal waters AVR, SUT, BCS and RCL-GW.

There is no significant correlation among all major

dissolved ions in cold/hypothermal waters out of the tran-

sect AA’ and rainwater: ASP-GIO, r = -0.24; ASP-JUV,

r = -0.16; RCL-GW, r = 0.51. Sodium and (bi)carbonate

are the dominant ions in the hyperthermal waters and cold

water RCL-GW, with existing significant correlation

among the major ions in RCL-GW and waters PPA

(r = 0.98), PPE-GW (r = 0.94), PEO (r = 0.92), ATA

(r = 0.99) and TLG (r = 0.92). These correlations justify

the similar variability of the parameters shown in Fig. 8 for

RCL-GW and the hyperthermal waters.

Fig. 6 The major cations and anions in the cold waters (samples

AVR and SUT) and hypothermal waters (sample BCS) plotted in a

Schoeller (1962) diagram together with the average values obtained in

rainwater (RW)

Fig. 7 The data for the samples of cold/hypothermal/hyperthermal

groundwaters collected at the Parana sedimentary basin (Tables 2, 3)

plotted on an Eh–pH diagram (Krauskopf and Bird 1995)

Environ Earth Sci

123

The Cl- dominance in groundwaters ASP-GIO and

ASP-JUV and (bi)carbonate dominance in RCL-GW

implied on non-significant correlations among major ions

in them, i.e. r = 0.52 and -0.22. None significant corre-

lation was also found among major ions in ASP-JUV and

hyperthermal waters, whereas significant values were

found between ASP-GIO and the following hyperthermal

waters: PPE-GW, r = 0.77; PEO, r = 0.76; TLG,

r = 0.82.

2H and 18O in rain and groundwater

The 2H and 18O data in rainwater reported in Table 1 were

obtained at the following monitoring stations (Fig. 1):

RCL-RW, SPO, BOT, ASB, ASI and PPE-RW. They have

been plotted in Fig. 9 together with other isotopes data

acquired at different stations spread in Sao Paulo State

(Fig. 1): (a) ADP-Aguas da Prata (Szikszay and Teissedre

1981); (b) SLO-Sao Carlos and RPT-Ribeirao Preto (Silva

1983); (c) SMS-Santa Maria da Serra, PIC-Piracicaba,

CAM-Campinas, BRP-Braganca Paulista and SAO-Sao

Paulo available from the website of the IAEA/WMO

(International Atomic Energy Agency/World Meteorolog-

ical Organization), in the GNIP (Global Network for Iso-

topes in Precipitation) database (IAEA 2006).

Thus, 2H and 18O data have been selected in circa 580

rainwater samples collected in Sao Paulo State, Brazil. The

stable nuclides 2H and 18O in rainwater show wide dis-

persion, with d18O values varying from -21.5 to ?4.9 %V-SMOW (mean -5.0 %) and d2H values ranging from

-162 to ?43.2 V-SMOW (mean -27.5 %). They scat-

tered around the regional meteoric waterline (RMWL)

(Fig. 9): d2H = 8.12 d18O ? 13.38. The slope and deute-

rium excess of the RMWL are slightly higher than those of

Fig. 8 The major cations and anions in the hyperthermal waters

collected along transect AA’ (samples PPA, PPE-GW and PEO)

plotted in a Schoeller (1962) diagram together with the data obtained

in groundwater sampled at Aracatuba, Tres Lagoas, Aguas de Sao

Pedro and Rio Claro municipalities (samples ATA, TLG, ASP-GIO,

ASP-JUV, RCL-GW)

Fig. 9 Top the regional meteoric waterline (RMWL) plotted from

d2H and d18O values in circa 580 rainwater samples collected in Sao

Paulo State, Brazil. Bottom the d2H and d18O data for the samples of

cold/hypothermal/hyperthermal groundwaters collected at the Parana

sedimentary basin (Tables 2, 3) plotted together with the global

meteoric water line (GMWL) and regional meteoric waterline

(RMWL)

Environ Earth Sci

123

the GMWL (d2H = 8 d18O ? 10) and both straight lines

intercept at d18O = -28.17 % and d2H = -215.36 %.

The highest RMWL inclination implies on slight d2H

enrichments in comparison to the GMWL (Fig. 9). In

general, differences in the deuterium excess have been

attributed to typical humidity and temperature of the clouds

formation sites, for instance, they range from ?13 to

?15 % in the occidental Mediterranean region (Clark and

Fritz 1997), whose interval comprises the value of

d2H = ?13.38 % defined by the RMWL (Fig. 9). Gast-

mans et al. (2010a) reported a d18O range from -15.8 to

?5.2 % and a d2H range from -111.4 to ?47 % in

rainwater provided from the monitoring station located at

Cuiaba city (Mato Grosso State). Some of these 2H and 18O

values are slightly more positive than the heaviest ones

plotted in Fig. 9, possibly as a consequence of the evapo-

ration effects coupled to the great differences in latitude/

longitude of Mato Grosso and Sao Paulo States in Brazil.

The 2H and 18O data in groundwater (Tables 2, 3) are

also plotted in Fig. 9. The d18O values range from -8.6 to

-5.3 % V-SMOW and the d2H values between -56.2 and

-31.7 % V-SMOW. All values fit the RMWL, indicating

that the groundwater origin in the different aquifer systems

investigated is directly related to the meteoric water

precipitation.

Gastmans et al. (2010b) suggested that at the GAS

northwestern portion, the silicate hydration and dissolution

reactions between the aquifer framework and the recharge

waters in the aquifer outcrop region could be responsible

for positioning the isotopic ratios of oxygen and hydrogen

above the global and local meteoric water lines. Such

positioning trend has also been identified in this paper for

the d2H and d18O data in groundwater and GMWL (Fig. 9).

However, it is not evident for the groundwater data and

RMWL that is more suitable to interpret the results

reported here.

The 2H and 18O data in groundwater collected along

transect AA’ do not vary significantly, as the d18O values

range from -7.9 to -6.9 % V-SMOW, whereas the d2H

values between -52.4 and -40.9 % V-SMOW (Table 2).

Such variation is not the same as that reported by Silva

(1983) in GAS at Sao Paulo State (d18O = -9.8 to

-6.3 % and d2H = -67 to -43 %) and is more negative

than the mean d18O and d2H values in rainwater (-5.0 and

-27.5 %, respectively), perhaps corresponding to water

recharged in cooler, higher altitude, inland or winter con-

ditions. Because the stable isotopes (2H and 18O) differ in

rainwater/groundwater and the dissolved chemical com-

positions change along transect AA’, then, it is not feasible

to apply the piston-flow model to the groundwater move-

ment (Geyh 2000).

One striking aspect concerning to d18O values in

groundwater collected along transect AA’ is the relative

constancy (variation between -7.9 and -6.9 %) in com-

parison with the cold/hypothermal and hyperthermal

characters of the waters. There is no trend towards more

negative values according to the groundwater flow direc-

tion in Sao Paulo State as proposed by Sracek and Hirata

(2002). Based on d18O values, Hirata et al. (2011) sug-

gested three GAS groundwater groups in Sao Paulo State as

an aid to interpret the groundwater flow pattern, where the

categories choice occurred considering values higher and

lower than -7 %. Such criterion is not supported by the

d18O data in groundwater sampled along transect AA’ as

the variable distance, temperature and chemistry (among

others parameters) are not accompanied by equivalent

modifications in the d18O values, whose mean is -7.2 %and total shift is only -1.0 %.

Sulfur and oxygen isotopes in sulfate dissolved

in groundwater

The 32S, 34S, 16O and 18O abundance is 95.0, 4.22, 99.76

and 0.20 %, respectively (Fritz and Fontes 1980). The

natural 34S/32S and 18O/16O ratios have been measured in

the dissolved SO4 and often used in hydrologic investiga-

tions for determining SO4 sources and pathways in the

sulfur cycle. The coupled use of d34S and d18OSO4 is a

useful tool to better constrain the origin/fate of sulfate and

to evaluate the transformations undergone by this solute

(Krouse and Van Everdingen 1986; Krouse et al. 1991;

Clark and Fritz 1997; Soler 2011). The d18OSO4 and d18-

Owater data reported in this paper were plotted in the dia-

gram proposed by Van Stempvoort and Krouse (1994). The

data insertion in Fig. 10 indicates that all dissolved sulfate

is obtained from dissolution of previous sulfate as the

d18OSO4 values are in disequilibrium with the oxygen from

water. Only the lighter data of samples PCS-MAC, PCS-

QSA, PCS-SIN and AXA should be the result of mixing

with sulfate from dissolution of previous sulfate and sulfate

coming from sulfide oxidation (in equilibrium with water

oxygen).

The dissolved sulfate in the cold/hypothermal ground-

water samples collected along transect AA’ was low,

0.22–0.39 mg/L, and no d34S and d18O data were acquired

for them. However, the values were higher (10.9–79.3 mg/L)

in the hyperthermal waters, and thus, the d34S and d18O

data in the dissolved sulfate were plotted in Fig. 10 against

the recharge beds distance (Botucatu city). The d34S in

sampling point PPA was ?2.0 %, rising to ?6.6 % (in

PPE-GW) or ?6.1 % (in PEO) and the d18Osulfate values

increased from ?14.1 % (in PPA) to ?15.5 % (in PPE-

GW) or ?14.9 % (in PEO), according to the groundwater

flow direction. Such isotopic evolution of the sulfate dis-

solved in water is typical during sulfate reduction pro-

cesses, where the preferential reaction involving 32S is

Environ Earth Sci

123

changed by a progressive enrichment in 34S of the residual

sulfate as also pointed out by Clark and Fritz (1997), Do-

gramaci et al. (2001), Bottrell et al. (2008), Hosono et al.

(2010), and Soler (2011), among others. The temperature

(43–70 �C), low redox potentials (Eh between -72 and

-55 mV), low dissolved oxygen content (2.4–3.2 mg/L)

and the presence of significant amount of organic matter in

sediments of the Passa Dois Group, Botucatu Formation

and Piramboia Formation (4–19 wt% according to dos

Anjos et al. 2010 and Bonotto 2013) provide an ideal

environment for bacterial SO4 reduction in this GAS sec-

tor. The lower Ehs (-72 to -55 mV) in the hyperthermal

waters relative to 144–200 mV in the cold/hypothermal

waters along transect AA’ (Table 2) is compatible with the

expected decreasing Eh conditions according to the

enhanced sulfate reduction processes (for instance, values

from 0 to -200 mV have been reported by Vance 1996).

The dissolved sulfate content range in groundwater

samples PPA, PPE-GW, PEO, ATA, TLG, ASP-GIO,

ASP-JUV and RCL-GW is 11–300 mg/L (Tables 2, 3),

constituting the dissolution of evaporites a potential SO4

source in GAS groundwater. In general, sulfates in waters

comprising dissolved evaporites are easy to identify

because of their d34S [10 % and d18Osulfate [12 %(Claypool et al. 1980). Highly positive d34S ([20 %) was

found in groundwater samples ASP-GIO and ASP-JUV,

Aguas de Sao Pedro city (Table 3). Cabral (1991) pointed

out that the Permian Irati Formation of the Passa Dois

Group is the unique sedimentary sequence of the Parana

basin in Sao Paulo State with potential to contain marine

evaporites. Santos Neto (1993) investigated a black shale-

carbonate sequence of the Irati Formation occurring close

to Aguas de Sao Pedro city and identified mm- to cm-thick

layers of gypsum and nodular anhydrite that indicated

confined evaporitic conditions. However, the Permian

marine sulfates often exhibit d34S values lighter than 20 %(Claypool et al. 1980), and therefore, the d34S and d18-

Osulfate values in dissolved sulfate occurring in samples

ASP-GIO and ASP-JUV should be mainly associated to

sulfate reduction processes. This suggests that some of the

lighter d34S-values (from ?6.1 to ?9.5 %) in groundwater

occurring at the Parana basin (Tables 2, 3) may be also

associated to the dissolution of evaporites.

The dissolved sulfate levels in groundwater discharging

through the lithologies at Pocos de Caldas and Araxa

municipalities range from 43 to 220 mg/L (Table 4) that is

within the concentration interval of the GAS groundwater.

The groundwater samples PCS-MAC, PCS-QSA, PCS-SIN

and AXA exhibit basic pH, transitional to reducing redox

potentials and composition dominated by major ions

δ18O

SO

4

δ18OH2O

Experimental area of sulfates derived by sulfur oxidation

Fig. 10 Top the d18OSO4 and

d18Owater data plotted in the

diagram proposed by Van

Stempvoort and Krouse (1994).

Diamonds samples PPA, PPE-

GW and PEO. Triangles

samples ATA, TLG, ASP-GIO,

ASP-JUV and RCL-GW.

Circles samples PCS-MAC,

PCS-QSA, PCS-SIN and AXA.

Bottom the d34S and d18Osulfate

values in groundwaters

collected along transect AA’

plotted against the recharge

beds distance (starting point

Botucatu city). The relationship

between d18Osulfate and d34S

values in the analyzed samples

is also shown

Environ Earth Sci

123

sodium and (bi)carbonate that is the same of the hyper-

thermal/cold waters PPA, PPE-GW, PEO, ATA, TLG and

RCL-GW in Parana basin. Despite these similar aspects,

their d18Osulfate ranging from ?6.0 to 8.1 % (Table 4) is

dominantly lighter than in groundwaters occurring at the

Parana basin (Fig. 10).

The hydrochemistry of aquifers and main primary

minerals occurring at Pocos de Caldas city area have been

investigated by Cruz and Peixoto (1989), Schorscher and

Shea (1992), Waber et al. (1992), and Bonotto (2005).

Table 4 reports the results of the speciation calculations

performed with the Aquachem 4.0 software, indicating that

negative mineral saturation indices were generated for the

sulfates anhydrite, gypsum and barite that suggest their

undersaturation. However, among them, only barite min-

eralization has been recognized at the site, which occurred

during a late stage of hydrothermal alteration (Waber et al.

1992). Nordstrom et al. (1992) evaluated the common-ion

effect of increased sulfate concentrations from pyrite oxi-

dation on the solubility of barite, reinforcing the impor-

tance of this mineral on the chemical composition of waters

at Pocos de Caldas city.

Traversa et al. (2001) investigated the petrography and

mineral chemistry of carbonatites and mica-rich rocks from

the Araxa complex. The groundwater sampling point AXA

(Table 4) is located at Barreiro, a circular intrusion, 4.5 km

in diameter, with the central part chiefly formed by a car-

bonatite predominantly beforsitic in composition (Traversa

et al. 2001). The results in Table 4 of the speciation cal-

culations performed with the Aquachem 4.0 software

indicate that the groundwater AXA exhibits a positive

mineral saturation index for barite, suggesting its oversat-

uration to this mineral phase.

Therefore, the d34S and d18Osulfate data of dissolved

sulfate shown in Fig. 10 clearly indicate quite variable

signatures. The groundwaters of the Pocos de Caldas

alkaline massif and Araxa carbonatitic alkaline complex

exhibit d18Osulfate values that are much lighter than in

groundwaters occurring at the Parana basin. The hyper-

thermal/cold waters PPE-GW, PEO, ATA, TLG and RCL-

GW (Parana basin) exhibit intermediate d34S value (mean

?7.8 %) to that of groundwaters PPA (d34S = ?2.0 %)

and ASP-GIO/ASP-JUV (mean d34S ?25.2 %). Despite

the previous d34S value to the sulfate reduction processes is

unknown, a rough estimate of mixing processes involving

the dissolved/reduced sulfate can be performed. If the

intermediate value is due to mixing of the ‘‘less reduced’’

sulfate (d34S = ?2.0 %) with the ‘‘more reduced’’ sulfate

(d34S = ?25.2 %), then simple mass balance calculations

using such end-members show that 0.25 is the fraction in

the mixture of the groundwater that possesses isotopic

composition related to the ‘‘more reduced’’ sulfate. This

calculation illustrates the use of d34S and d18Osulfate data in

dissolved sulfate for investigating mixing processes in the

GAS. The rate of sulfate-reducing bacteria growth at 20 �C

is much higher than that at 50 �C (Al-Zuhair et al. 2008),

what favors the adoption of the heavier d34S value as an

end-member, since the water temperature at sampling

points ASP-GIO and ASP-JUV is 23–25 �C (Table 3).

Implications of the acquired data to previous studies

in GAS

The transect AA’ shown in Figs. 1 and 2 was previously

studied by Silva (1983), Araujo et al. (1999), Sracek and

Hirata (2002), Bonotto (2006), and Cresswell and Bonotto

(2008). In view of dissolved gasses, physical and chemical

parameters involving major and some trace elements,

Bonotto (2006) admitted that waters from GAS provided

from deeper wells should be mixing with those flowing

through the underlying Paleozoic sediments. Table 2

indicates that practically only bores AVR and BCS are

slotted within the GAS (Botucatu and Piramboia forma-

tions). Cresswell and Bonotto (2008) pointed out that bores

PPA and PEO are from the underlying Parana Group

aquifer (Devonian) while bore PPE-GW appears to be

sourced in the Passa Dois Group, which is predominantly

the basal aquitard to the GAS. Additionally, bore SUT

appears to be in the recharge beds of bores PPA and PEO,

but it is in a diabase sill of unknown extent (Cresswell and

Bonotto 2008).

Despite these features, the transect AA’ has been

sometimes used to illustrate a flow path through the main

sequence of the GAS, on the grounds that the sequence is

well-connected vertically. For instance, Sracek and Hirata

(2002) developed a conceptual model of water chemistry

evolution in Sao Paulo State, proposing possible mecha-

nisms to convert Ca–HCO3 waters, in the recharge areas, to

Na–HCO3/Na–Cl–SO4 waters in confined zones. Sracek

and Hirata (2002) considered that the Na inputs through

dissolution could not explain the observed concentrations

downgradient and suggested that the cation exchange of

Ca2? in groundwater for Na? on exchange sites through a

reaction that increases sodium and bicarbonate concentra-

tions and decreases calcium concentrations could explain

the hydrochemical evolutionary path.

However, the chemical data of Sracek and Hirata (2002)

did not constitute a simple evolutionary water progression

as required different processes to explain each section of

transect AA’. The mechanisms proposed did not take into

account several physical and chemical parameters reported

in this paper like major ions, trace elements and stable

isotopes, mainly in hyperthermal waters. Thus, processes

involving carbonates precipitation due to temperature

increasing were not considered in the modeling presented

by Sracek and Hirata (2002), as well the occurrence of

Environ Earth Sci

123

mixing processes involving GAS and pre-GAS waters. This

is particularly important in the case of the hyperthermal

waters as the deep bores PPA, PPE-GW and PEO are

probably sourcing waters from the pre-GAS sequences,

which are beneath of Botucatu and Piramboia formations.

Therefore, several data reported in this paper revealed

the importance of dissolution processes affecting pre-GAS

sediments, thus, reinforcing the initial findings of Bonotto

(2006). The author provided evidences to the GAS zoning

proposed by Gastmans et al. (2010b) who suggested an

area where the aquifer is overlain by thicknesses of basalts

[500 m, in which the waters would be enriched in Na?,

Cl- and SO42- due to mixing with saline waters from

underling aquifers units. They also supported the mecha-

nisms’ re-evaluation performed by Hirata et al. (2011) in

view of the presence of relatively high Cl- and SO42-

concentrations in the deep confined portions of the GAS,

which have not been considered only associated with the

geochemical evolution of water, following the groundwater

flow. Hirata et al. (2011) also recorded the importance to

the saline waters of some units underlying the GAS like the

sedimentary rocks of the Corumbataı/Teresina and Rio do

Rastro formations.

The results of this study indicated the possibility of

performing new insights on approaches realized in previous

studies. For instance, Gastmans et al. (2010b) pointed out

that in the GAS recharge zones, enriched d18Owater values

are observed, while in the confined zone lighter d18Owater

values are observed, suggesting that climatic conditions

were 10 �C cooler than the present during the recharge of

these waters. The d18Owater data reported here do not fol-

low this trend possibly due to the great differences in lat-

itude/longitude of the areas studied. Gastmans et al.

(2010b) also verified increasing of the d13C values in GAS

groundwater along the regional flow lines towards the

confined zone, relating it to dissolution of carbonate

cement in the sandstones. However, the temperature and

mixing effects as reported here could imply on another

scenario. This new hydrochemical/isotopes database/

approach also suggests some caution on the use of the

groundwater groups classification based on d18Owater val-

ues and GAS flow dynamics in Sao Paulo State and sur-

roundings (Hirata et al. 2011) or the GAS dating based on

the natural U-isotopes and 36Cl modeling (Bonotto 2006;

Cresswell and Bonotto 2008).

Conclusions

This novel hydrochemical/isotopes database in rainwater

and groundwaters of the Guarani Aquifer System (GAS)

has been interpreted according to the groundwater tem-

perature: the cold/hypothermal waters (\25–33 �C)

exhibited higher values of dissolved O2, free CO2, redox

potential Eh and lower values of pH, conductivity, TDS,

Na?, Cl-, SO42-, HCO3

- ?CO32-, Al, Li, F, Br, Co, Mn,

As and Mo relative to the hyperthermal ones ([38 �C).

However, the Ca2? and Mg2? contents were higher in the

cold/hypothermal waters, possibly related to the fact that

the carbonate mineral reactivity in aqueous solution tends

to decrease at higher temperatures and partial CO2 pres-

sure. The stable nuclides 2H and 18O in rainwater scattered

around the regional meteoric waterline (RMWL):

d2H = 8.12 d18O ? 13.38. The 2H and 18O data in

groundwater fitted the RMWL, indicating that the

groundwater origin is directly related to the meteoric water

precipitation. The d34S and d18Osulfate data of dissolved

sulfate pointed out that the dissolution of evaporites and

bacterial SO42- reduction processes are occurring at the

GAS, affecting the groundwater composition. The d34S and

d18Osulfate values along the GAS transect studied here

changed according to the groundwater flow direction in a

way that is compatible with the occurrence of sulfate

reduction processes as supported by the temperature, redox

potentials, dissolved oxygen content and organic matter

presence in the sediments. The d34S and d18Osulfate data of

dissolved sulfate allowed utilization of simple mass bal-

ance calculations to investigate possible mixing processes

involving the dissolved/reduced sulfate, contributing to

further GAS studies.

Acknowledgments FAPESP (Foundation Supporting Research in

Sao Paulo State) and CNPq (National Council for Scientific and

Technologic Development) in Brazil are greatly thanked for financial

support of this investigation. This work has also been financed by the

projects CGL2011-29975-C04-01 from the Spanish Government, and

partially by the project 2009SGR 103 from the Catalan Government.

The Centres Cientıfico-Tecnics of the Universitat de Barcelona is also

acknowledged for the sulfate isotopic analysis. Two anonymous ref-

erees are thanked by helpful comments that improved the readability

of the mannuscript.

References

Almeida FFM, Melo MS (1981) The Parana basin and Mesozoic

volcanism. In: IPT (Technological Research Institute of Sao

Paulo State) (ed.) Geological map of Sao Paulo State. Promocet,

Sao Paulo, vol 1, pp 46–81

Al-Zuhair S, El-Naas MH, Al-Hassani H (2008) Sulfate inhibition

effect on sulfate reducing bacteria. J Biochem Technol

1(2):39–44

APHA (1989) Standard methods for the examination of water and

wastewater, 17th edn. American Public Health Association,

Washington, DC

Araujo LM, Franca AB, Potter PE (1999) Hydrogeology of the

Mercosul aquifer system in the Parana and Chaco-Parana Basins,

South America, and comparison with the Navajo-Nugget aquifer

system, USA. Hydrogeol J. 7:317–336

Bonotto DM (2004) Doses from 222Rn, 226Ra, and 228Ra in

groundwater from Guarani aquifer, South America. J Environ

Radioact 76:319–335

Environ Earth Sci

123

Bonotto DM (2005) The U-isotopes modeling in aquifers from Pocos

de Caldas plateau, Brazil. Environ Geol 48:507–523

Bonotto DM (2006) Hydro(radio)chemical relationships in the giant

Guarani aquifer, Brazil. J Hydrol 323:353–386

Bonotto DM (2011) Natural radionuclides in major aquifer systems of

the Parana sedimentary basin, Brazil. Appl Radiat Isot

69:1572–1584

Bonotto DM (2013) A comparative study of aquifer systems

occurring at the Parana sedimentary basin: U-isotopes contribu-

tion. Environ Earth Sci 68:1405–1418

Bonotto DM, Armada PCP (2008) Radon and progeny (214Pb and214Bi) in urban water-supply systems at Sao Paulo State, Brazil.

Appl Geochem 23:2829–2844

Bonotto DM, Bueno TO (2008) The natural radioactivity in Guarani

aquifer groundwater, Brazil. Appl Radiat Isot 66:1507–1522

Bonotto DM, Caprioglio L (2002) Radon in groundwaters from

Guarany aquifer, South America: environmental and exploration

implications. Appl Radiat Isot 57:931–940

Bonotto DM, Mello CB (2006) A combined method for evaluating

radon and progeny in waters and its use at Guarani aquifer, Sao

Paulo State, Brazil. J Environ Radioact 86:337–353

Bonotto DM, Bueno TO, Tessari BW, Silva A (2009a) The natural

radioactivity in water by gross alpha and beta measurements.

Radiat Meas 44:92–101

Bonotto DM, Caprioglio L, Bueno TO, Lazarindo JR (2009b)

Dissolved 210Po and 210Pb in Guarani aquifer groundwater,

Brazil. Radiat Meas 44:311–324

Bottrell S, Tellam J, Bartlett R, Hughes A (2008) Isotopic compo-

sition of sulfate as a tracer of natural and anthropogenic

influences on groundwater geochemistry in an urban sandstone

aquifer, Birmingham, UK. Appl Geochem 23:2382–2394

Campos HCNS (2000) Hydrogeological map of Guarani aquifer. Acta

Geol Leopoldensia 23(4):1–50

Castany G (1982) Principes et methodes de l’hydrogeologie. Dunod,

Paris

Clark I, Fritz P (1997) Environmental isotopes in hydrology. Lewis,

Boca Raton, p 312

Claypool GE, Holser WT, Kaplan IR, Sakai H, Zak I (1980) The age

curves of sulfur and oxygen isotopes in marine sulfate and their

mutual interpretation. Chem Geol 28:199–261

Cresswell RG, Bonotto DM (2008) Some possible evolutionary

scenarios suggested by Cl-36 measurements in Guarani aquifer

groundwaters. Appl Radiat Isot 66:1160–1174

Cruz WB (1987) Hydrogeological and hydrochemical evaluation at

Pocos de Caldas city. Tech. Rep., Foundation of Minas Gerais

Technological Center, Belo Horizonte, p 152

Cruz WB, Peixoto CAM (1989) Thermal waters from Pocos de

Caldas, MG: experimental study of water-rock interactions. Rev

Bras Geoc 19:76–86

DFPM (Division for Supporting the Mineral Production) (1966) The

mining code, the mineral waters code and how applying research

in a mineral deposit. Rep. 91, 8th edn. DFPM, Rio de Janeiro,

p 109

Dogramaci SS, Herczeg AL, Schiff SL, Bone Y (2001) Controls on

d34S and d18O of dissolved sulfate in aquifers of the Murray

Basin, Australia and their use as indicators of flow processes.

Appl Geochem 16:475–488

dos Anjos CWD, Meunier A, Guimaraes EM, el Albani A (2010)

Saponite-rich black shales and nontronite beds of the Permian

Irati Formation: sediment sources and thermal metamorphism

(Parana basin, Brazil). Clay Clay Miner 58(5):606–626

Faure G (1991) Principles and applications of inorganic geochemis-

try. MacMillan Publishing Company, New York, p 626

Foster S, Kemper K, Garduno H, Hirata R, Nanni M (2006) The

Guarani aquifer initiative for transboundary groundwater man-

agement. case profile collection 9, sustainable groundwater

management—lessons from practice. The World Bank, Wash-

ington, DC

Fritz P, Fontes JC (1980) Handbook of environmental isotope

geochemistry, vol 1. Elsevier, Amsterdam, p 545

Gastmans D, Chang HK, Hutcheon I (2010a) Stable isotopes (2H, 18O

and 13C) in groundwaters from the northwestern portion of the

Guarani Aquifer System (Brazil). Hydrogeol J 18:1497–1513

Gastmans D, Chang HK, Hutcheon I (2010b) Groundwater geochem-

ical evolution in the northern portion of the Guarani Aquifer

System (Brazil) and its relationship to diagenetic features. Appl

Geochem 25:16–33

Gastmans D, Veroslavsky G, Chang HK, Marmisolle J, Oleaga A

(2010c) Influence of the hydrostratigraphic outline on the arsenic

occurrences in groundwater along the thermal corridor of Uruguay

river (Argentine-Brazil-Uruguay). Geociencias 29(1):105–120

Geyh M (2000) Groundwater-Saturated and unsaturated zone. In:

UNESCO-IAEA (eds) Environmental Isotopes in the Hydrolog-

ical Cycle: Principles and Applications. UNESCO-IAEA, Paris-

Vienna, vol 4, pp 25–39

Gilboa Y, Mero F, Mariano IB (1976) The Botucatu aquifer of South

America, model of an untapped continental aquifer. J Hydrol

29:165–179

HACH (1992) Water analysis handbook, 2nd edn. Hach Company,

Loveland, p 831

Hirata R, Gesicki A, Sracek O, Bertolo R, Giannini PC, Aravena R

(2011) Relation between sedimentary framework and hydroge-

ology in the Guarani Aquifer System in Sao Paulo state, Brazil.

J S Am Earth Sci 31:444–456

Hosono T, Siringan F, Yamanaka T, Umezawa Y, Onodera S, Nakano

T, Taniguchi M (2010) Application of multi-isotope ratios to

study the source and quality of urban groundwater in Metro

Manila, Philippines. Appl Geochem 25:900–909

IAEA (International Atomic Energy Agency)/WMO (World Meteo-

rological Organization) (2006) Global Network of Isotopes in

Precipitation: the GNIP database, http://isohis.iaea.org

Kimmelmann e Silva AA, Reboucas AC, Santiago MMF (1989) 14C

analysis of groundwater from the Botucatu aquifer system in

Brazil. Radiocarbon 31(3):926–933

Kimmelmann AA, Forster M, Coelho R (1995) Environmental

isotope and hydrogeochemical investigation of Bauru and

Botucatu aquifers, Parana basin, Brazil. In: IAEA (International

Atomic Energy Agency) (ed.) Isotope hydrology investigations

in Latin America 1994. IAEA-TECDOC-835, IAEA, Vienna,

pp 57–74

Krauskopf KB, Bird DK (1995) Introduction to geochemistry.

McGraw-Hill Inc., New York

Krouse HR, Van Everdingen RO (1986) Interpretation of oxygen

isotope data for sulphate in subsurface waters. In: IAGC (Int.

Assoc. Geochemistry and Cosmochemistry) (ed) Proceedings of

5th International Symposium Water-Rock Interaction, Reykja-

vik, pp 663–666

Krouse HR, Gould WD, McCready RGL, Raja S (1991) O

incorporation into sulphate during the bacterial oxidation of

sulphide minerals and the potential for oxygen isotope exchange

between O2, H2O and oxidized sulphur intermediates. Earth

Planet Sci Lett 107:90–94

Cabral Jr. M (1991) Metallogenetic possibilities of the Parana basin in

Sao Paulo State: phosphorites, evaporites and base metals. MS

Dissertation, UNESP-Sao Paulo State University, Rio Claro

Mancini LH (2002) 226Ra and 228Ra migration in superficial and

groundwater of the Barreiro do Araxa (MG) alkaline complex.

PhD Thesis, UNESP- Sao Paulo State University, Rio Claro

Meng SX, Maynard JB (2001) Use of statistical analysis to formulate

conceptual models of geochemical hehavior: water chemical

data from the Botucatu aquifer in Sao Paulo State, Brazil.

J Hydrol 250:78–87

Environ Earth Sci

123

Mook WG (2000) Water sampling and laboratory treatment. In:

UNESCO-IAEA (eds) Environmental isotopes in the hydrolog-

ical cycle: principles and applications. UNESCO-IAEA, Paris-

Vienna, vol 1, pp 167–178

Nordstrom DK, McNutt RH, Puigdomenech I, Smellie JAT, Wolf M

(1992) Ground water chemistry and geochemical modeling of

water-rock interactions at the Osamu Utsumi mine and the

Morro do Ferro analogue study sites, Pocos de Caldas, Minas

Gerais, Brazil. J Geochem Explor 45:249–287

Pelicho AF, Martins LD, Nomi SN, Solci MC (2006) Integrated and

sequential bulk and wet-only samplings of atmospheric precip-

itation in Londrina, South Brazil (1998-2002). Atmos Environ

40:6827–6835

Pinet PR (2006) Invitation to oceanography, 4th edn. Sudbury, Jones

& Bartlett Pub., p 595

Pokrovsky OS, Golubev SV, Schott J, Castillo A (2009) Calcite,

dolomite and magnesite dissolution kinetics in aqueous solutions

at acid to circumneutral pH, 25 to 150 �C and 1–55 atm pCO2:

new constraints on CO2 sequestration in sedimentary basins.

Chem Geol 265(1–2):20–32

Santos Neto EV (1993) Geochemical characterization and deposi-

tional palaeoenvironment of the Upper Carbonate-Pelitic

Sequence from Assistencia Member, Irati Formation in Sao

Paulo State, Parana basin. MS Dissertation, UFRJ-Federal

University of Rio de Janeiro, Rio de Janeiro, p 203

Schoeller H (1962) Les eaux souterraines. Masson & Cie, Paris, p 642

Schorscher HD, Shea ME (1992) The regional geology of the Pocos

de Caldas alkaline complex: mineralogy and geochemistry of

selected nepheline syenites and phonolites. J Geochem Explor

45:25–51

Silva RBG (1983) Hydrochemical and isotopic study of groundwater

from Botucatu aquifer in Sao Paulo State. PhD Thesis, USP-Sao

Paulo University, Sao Paulo

Soares PC (1975) Stratigraphic division of Mesozoic in Sao Paulo

State. Rev Bras Geoc 5:229–251

Soler A (2011) Environmental applications of the stable isotopes 34S,18O, 15N, 11B. In: FCIHS (Foundation of the International Center

of Underground Hydrology) (ed) 45 International Course of

Underground Hydrology. FCIHS, Barcelona

Sracek O, Hirata R (2002) Geochemical and stable isotopic evolution

of the Guarani Aquifer System in the state of Sao Paulo, Brazil.

Hydrogeol J 10:643–655

Szikszay M, Teissedre JM (1981) Springs of the Parana sedimentary

basin, Sao Paulo State. Rev Aguas Subterran 3:85–102

Teissedre JM, Barner U (1981) Geothermal and geochemical

behavior of waters from Botucatu aquifer in Parana basin. Rev

Aguas Subterran 4:85–95

Traversa G, Gomes CB, Brotzu P, Buraglini N, Morbidelli L,

Principato MS, Ronca S, Ruberti E (2001) Petrography and

mineral chemistry of carbonatites and mica-rich rocks from the

Araxa complex (Alto Paranaıba Province, Brazil). An Acad Bras

Ci 73(1):71–98

Van Stempvoort DR, Krouse HR (1994) Controls of d18O in sulfate.

In: Alpers CN, Blowes DW (eds) Environmental geochemistry

of sulphide oxidation. American Chemical Society, Washington,

DC, pp 446–480

Vance DB (1996) Redox reactions in remediation. Environ Technol

6(4):24–25

Velde B (1992) Introduction to clay minerals: chemistry, origins, uses

and environmental significance. Chapman & Hall, London

Waber N, Schorscher HD, Peters T (1992) Hydrothermal and

supergene uranium mineralization at the Osamu Utsumi mine,

Pocos de Caldas, Minas Gerais, Brazil. J Geochem Explor

45:53–112

WHO (World Health Organization) (2011) Guidelines for drinking-

water quality, 4th edn. WHO Press, Geneva

Environ Earth Sci

123