ORIGINAL ARTICLE
Geochemistry and potential use of groundwaterin the Rocca Busambra area (Sicily, Italy)
M. Fontana Æ F. Grassa Æ G. Cusimano Æ R. Favara ÆS. Hauser Æ C. Scaletta
Received: 15 January 2008 / Accepted: 3 May 2008 / Published online: 20 June 2008
� Springer-Verlag 2008
Abstract In the Rocca Busambra area (mid-west Sicily,
Italy), from November 1999 to July 2002, 23 water points
including wells and springs were sampled and studied for
their chemical and isotopic compositions. Two rain gauges
were also installed at different altitudes, and rainwater was
collected monthly to determine the isotopic composition.
The obtained results revealed the Rocca Busambra car-
bonate complex as being the main recharge area on account
of its high permeability value. From a chemical view point,
two main groups of water can be distinguished: calcium–
magnesium–bicarbonate-type and calcium–magnesium–
chloride–sulphate-type waters. The first group reflects the
dissolution of the carbonate rocks; the second group
probably originates from circulation within flyschoid sed-
iments. Three water wells differ from the other samples
due to their relatively high Na and K content, which
probably is to be referred to a marked interaction with the
‘‘Calcareniti di Corleone’’ formation, which is rich in
glauconite [(K, Na)(Fe3+, Al, Mg)2(Si, Al)4O10(OH)2]. In
accordance with WHO guidelines for drinking water
(2004), almost all the samples collected can be considered
drinkable, with the exception of four of them, whose NO3-,
F- and Na+ contents exceed the limits. On the contrary, the
sampled groundwater studied is basically suitable for
irrigation.
Keywords Water quality � Environmental isotopes �Geochemistry � Italy
Introduction
Water is universally considered as being a blessing,
because its availability influences the quality of life of
every population. This concept is of particular importance
in Sicily, where there are often problems regarding water
supply. It should, however, be said that the water crises in
question are not always related to the arid climate, when
rainfall is not always sufficient to satisfy requirement, but
are often, instead, caused by insufficient planning and
management of the water resources. The new Italian reg-
ulations in the matter of water requires the study of all the
superficial water bodies and groundwater to monitor,
safeguard and manage these resources both from a quan-
titative and qualitative standpoint.
The Rocca Busambra area is a region extending for
about 140 km2 in the mid-west Sicily (Italy). It is charac-
terized by an important carbonate relief (Rocca Busambra)
arising in the middle of an extended outcrop of flysch. In
the past, the studied area was intensely investigated only
for its main structural, depositional and tectonic features.
The presence of several springs with a total annual flow
rate in the order of hundreds of liters per second sur-
rounding the carbonate massif provoked our interest to
investigate the circulation of groundwater in the most
important hydrological structures of the Rocca Busambra
area and to evaluate its potential use (for drinking or
M. Fontana (&) � F. Grassa � G. Cusimano � R. Favara �S. Hauser � C. Scaletta
Istituto Nazionale di Geofisica e Vulcanologia - Sezione di
Palermo, Via La Malfa 153, 90146 Palermo, Italy
e-mail: [email protected]
G. Cusimano
Dipartimento di Geologia e Geodesia, Universita di Palermo,
Corso Tukory 131, 90134 Palermo, Italy
S. Hauser
Dipartimento di Chimica e Fisica della Terra,
Universita di Palermo, Via Archirafi 36, 90123 Palermo, Italy
123
Environ Geol (2009) 57:885–898
DOI 10.1007/s00254-008-1368-z
irrigation). Therefore, the water resource in the studied area
was evaluated through a preliminary water budget.
Water quality depends strongly on the water–rock
interaction processes and of course also on the anthropic
activities. Therefore, this study was focused mainly on the
hydrochemical characterization of groundwater flowing
within the Rocca Busambra, aimed to the distinction
between solutes deriving leaching of host rocks and those
produced by the effects of human pollution.
From November 1999 to July 2002, more than 20 water
samples periodically collected from the most representative
wells and springs were analyzed for their chemical and
isotope composition. During the same period, two rain
gauges were also installed to determine the isotope signa-
ture of the local meteoric recharge.
On the basis of the obtained results, a conceptual geo-
chemical model of groundwater circulation in the Rocca
Busambra area is here proposed. Finally, concentration of
major solutes allowed to define whether or not these waters
could be used for drinking purposes or for agricultural
irrigation.
The quality of the groundwater has been evaluated on
the basis of the concentration of major solutes. Interna-
tional standards for drinking water set by the World Health
Organization (2004) were used as references to evaluate
whether or not these waters could be used for drinking
purposes. On the other hand, to evaluate whether water is
suitable for agricultural purposes, all the collected samples
were plotted on the Wilcox diagram (Wilcox 1955).
Studied area
Geology
The study area, located in mid-west Sicily, extends for
approximately 140 km2 (Fig. 1). It consists of a carbonate
dorsal (Rocca Busambra) having a maximum height of
1,613 m above mean sea level (a.m.s.l.), and is surrounded
by flyshoid deposits. The outcropping rocks belong to three
different tectonic units (Catalano and D’Argenio 1982;
Roure et al. 1990; Lentini et al. 1994; Vitale 1995; Agate
et al. 1998), which originate from the deformation, in
Miocene age, of pre-existing paleo-geografic domains: (1)
a carbonatic unit that originated from the partial defor-
mation of the Imerese–Sicano domain, which mainly
emerges in the north-eastern portion of the study area
(Pizzo Chiarastella); (2) another prevailing carbonate unit
that originated from the deformation of the Trapanese
domain, which forms the Rocca Busambra dorsal almost
entirely and (3) the Numidian Flysch, which occupies most
of the studied territory. Late-orogenic terrains overlie the
abovementioned units.
Hydrogeology
On the basis of the lithology and geologic-structural aspects,
in the studied area, the presence of various hydrogeological
complexes has been recognized. Furthermore, from a point
of view of hydraulic conductivity (K), three main hydro-
geological complexes have been distinguished:
• High hydraulic conductivity (K [ 10-4 m s-1)
• Medium hydraulic conductivity (10-7 m s-1 \ K \10-4 m s-1)
• Poor hydraulic conductivity (K \ 10-7 m s-1)
The high hydraulic conductivity complex includes the
following:
Carbonate
complex (Rocca
Busambra and Pizzo
Chiarastella)
The carbonatic sequences of the
Imerese–Sicano (Late Triassic–
Eocene) and Trapanese domains
(Late Triassic–Paleocene) belong to
this complex. Both the intense
fracturing and the impressive
development of karst structures
confer a high secondary perme-
ability to this complex. The huge
extension coupled with high
permeability characteristics makes
this complex as the main potential
recharge area.
Arenaceous
complex
It is made up of calcarenites
(Aquitaniano–Langhiano), rich in
glauconite, of a gray-greenish
color, better known as ‘‘Calcareniti
di Corleone’’ (Trapanese domain)
and of quartz–arenites of the
Numidian Flysch (Late Oligocene–
Early Miocene). The permeability of
the first lithotype is strongly
dependent on the degree of
cementation, while the permeability
of the flyschoid deposits is to be
referred to the degree of fracturing
rather than to the porosity.
Evaporite
complex
It includes the evaporite deposits
(Messinian in age) belonging to the
late-orogene terrains. Although this
complex is highly permeable,
mainly due to the occurrence of
karst structures, it has a marginal
role in the groundwater circulation
of the study area because of its small
size.
The complexes belonging to the medium hydraulic
conductivity group are as follows:
886 Environ Geol (2009) 57:885–898
123
Marl-carbonate
complex
It has secondary hydraulic conductivity
due to fractures and karst structures.
This complex is mainly made up of
microcrystalline calcilutites, alternated
by marls, belonging to the Amerillo
Formation (Late Cretaceous–Eocene;
Trapanese domain) and Caltavuturo
Formation (Late Cretaceous–Eocene;
Imerese–Sicano domain).
Clay-sandy
complex
These are terrigenous deposits of
the Terravecchia formation (Upper
Tortonian–Lower Messinian). Sandy
and conglomeratic layers have moderate
hydraulic conductivity due to primary
porosity; this complex is almost
impermeable in correspondence with
the outcroppings of clay deposits.
The clay deposits, which represent the largest outcrop-
ping in the study area (about 90 km2), belong to the poor
hydraulic conductivity complex. It consists mainly of the
Mufara Formation (Carnico; Imerese–Sicano domain), the
‘‘Marne di S. Cipirrello’’ (Langhiano–Early Tortonian;
Trapanese domain) and Numidian Flysch (Upper Oligo-
cene–Lower Miocene).
Climate setting
In spite of its relatively high mean annual precipitation
(about 750 mm year-1), the Rocca Busambra area can be
considered as having a mainly semiarid climate. The cli-
matic characteristics of the study area are well known on
account of the temperature and rainfall data collected from
1921 to 1999 by eight stations belonging to the Hydrog-
raphical Service of the Sicilian Region network. In
particular, it has been possible to observe that the rainy
period occurs in winter, between November and February,
whereas the dry season is summertime, from June to
August. As regards temperatures, the lowest values (about
7�C) have been recorded in February, while August is the
hottest month with average temperatures of 27�C.
In Fig. 2, monthly precipitation data collected during the
observation period have been compared with those
regarding the long term observation period (1921–1999);
they have highlighted marked anomalies both in the
monthly and in the annual amounts of rainfall.
Water budget
In the framework of the aim of this study, the water
resource in the Rocca Busambra area was evaluated
Fig. 1 Hydrogeological map of the studied area. The location of the 23 water points and the two rain gauges collected are also reported
Environ Geol (2009) 57:885–898 887
123
through a preliminary water budget. For this, computation
was developed as a very simple model having as few
parameters as possible as suggested by Dooge (1977).
The starting point in evaluating water resource was to
determine the components of the water balance defined by
the following equation:
P ¼ Er þ I þ R
where P represents the amount of rainfall, Er is the effec-
tive amount of water lost during evapotranspiration, I is the
net infiltration and R is surface runoff.
Long term record of monthly precipitation and temper-
ature data (1921–1999) were available from eleven (P) and
seven (T) stations belonging to the Hydrographical Service
of the Sicilian Region network. To estimate the amount of
precipitation (P), the territory was divided into 11 subareas
following the method proposed by Thiessen (1911). Each
of the obtained areas represents the part of territory influ-
enced by the rain gauge station in it. The monthly amount
of rainfall (Pt) was computed as the monthly average value
weighted on the basis of the size of the subareas. The
annual precipitation (P), obtained by summing the twelve
monthly precipitation, resulted as being about 750 mm.
For computing the monthly effective evapotranspiration
(Ert), two main factors were used: (1) the monthly precipi-
tation (Pt) and (2) the monthly potential evapotranspiration
(Ept) as follows:
Ert ¼ min Pt; Ept
� �
The Ept factor was computed following the methods pro-
posed by Thornthwaite (1948) and Turc (1955).
Because Thornthwaite’s equation and Turc’s formula
generally produce Ept values, which tend to be underesti-
mated and overestimated respectively, to obtain a more
accurate calculation, an average value between those
computed applying the two methods described above was
taken into account. In Fig. 3, the temporal trends of the Ert,
Pt, Ept and Pe factors computed for the Rocca Busambra
region were plotted.
It can be noted that in the studied area from October to
March, the Ert is equal to Ept, since the monthly amount of
rainfall (Pt) is greater than the monthly potential evapo-
transpiration (Ept), whereas, in the remaining period of the
hydrologic year (from April to September), the Ept prevails
on the Pt and, therefore, the effective monthly evapo-
transpiration (Ert) is equal to Pt. As a result, during the
whole year, the total amount of water lost by evapotrans-
piration was estimated to be approximately 400 mm,
corresponding to 53% of the total annual precipitation.
By subtracting Er from P, the effective amount of pre-
cipitation (Pe), which represents the effective volume of
water available in the field (I + R) was obtained. To esti-
mate the parameter I for each of the outcropping
lithologies, the potential infiltration coefficient (p.i.c.) was
used (Celico 1986). This parameter expresses the per-
centage of infiltrating water in respect of effective
precipitation, as follows:
p.i.c. ¼ Pe
I
The I value, averaged on the relative extension of each
outcropping is around 85 mm (12% of the total precipita-
tion) and corresponds to an annual water availability of
about 2–3 9 107 m3 year-1. Nonetheless, the exact num-
ber of water points and consequently the total volume of
water discharged from the studied area is unknown; these
preliminary results seem to fit roughly the water discharge.
In fact, flow-rates of the spring nos. 9 and 10, two of the
most relevant water discharges in the Rocca Busambra
area, solely account for at least 10–15% of the total volume
of water.
Once P, Er, and I were computed, R was finally calcu-
lated as a difference. A value of 260 mm (about 35% of the
total annual precipitation) was obtained.
Fig. 2 Comparison between the monthly precipitation collected
during the year 2000 and those relative to long term observation
period (1921–1999)
Fig. 3 Temporal trends of Ert (dotted area), Pt (open diamonds), Ept
(closed squares) and Pe (dotted line) factors computed for the Rocca
Busambra region
888 Environ Geol (2009) 57:885–898
123
Field and analytical methods
Water temperature, pH, Eh and electrical conductivity (EC)
measurements were carried out directly at the sampling
points. Alkalinity determination was carried out in the
laboratory by means of HCl titration. Major dissolved
constituents were determined by ion-chromatography.
From December 1999 to November 2000, rain water
was collected monthly from two rain gauges located at
different elevations (i.e. PC at 800 m and PM at 530 m
a.m.s.l.). To prevent evaporation, 250 ml of liquid Vase-
line (CAS No. 8009-03-8) was introduced into the
collector.
The D/H ratios were determined via reduction with zinc
(Coleman et al. 1982) and the isotope measurements were
performed by a Delta Plus Finnigan IRMS. The 18O/16O
ratios were determined through CO2–H2O equilibration,
using an automatic preparation line, and the measurements
were carried out by an AP 2003 mass-spectrometer. The
results obtained have been reported in d per mil versus V-
SMOW international standard. The repeatability of the
isotope measurements is ±1% and ±0.1% for D/H and18O/16O, respectively.
Water classification
From November 1999 to July 2002, 23 water points such as
wells and springs were periodically sampled. Their physi-
cochemical parameters, as well as major and minor
dissolved constituents, are reported in Tables 1 and 2 as
mean, maximum and minimum values.
The Langelier–Ludwig diagram (Langelier and Ludwig
1942) in Fig. 4 shows that the samples are mainly con-
centrated in two groups: the first group (A) includes typical
calcium–magnesium–bicarbonate-type waters, whereas the
second one (B) straddles the field of calcium–magnesium–
chloride–sulphate-type and calcium–magnesium–bicar-
bonate-type waters.
Group A consists of ten water points, six of them (nos. 3,
4, 5, 6, 13 and 23) are located close to the dorsal while the
other four (nos. 9, 10, 21 and 22) are outflows that are
located along the western flank. These waters show annual
mean TDS values between 290 mg/l (no. 5) and 539 mg/l
(no. 4). The main chemical features of these waters
(Ca C Mg–HCO3-type) suggest an interaction between
meteoric waters and the carbonate rocks that form the
Rocca Busambra massif.
Table 1 Mean, minimum and maximum values of the physicochemical parameters of the waters collected
No. Temperature (�C) pH Eh (mV) EC (lS/cm) TDS (mg/l) n
Mean Min. Max. Mean Min. Max. Mean Min. Max. Mean Min. Max. Mean Min. Max.
1 11.8 8.8 14.5 7.3 6.7 7.6 28 -17 116 660 553 789 545 464 611 14
2 12.3 8.4 15.9 6.8 6.6 7.1 13 -15 34 417 326 495 315 300 332 4
3 11.3 6.5 17.1 7.9 7.2 8.2 123 86 178 399 318 538 347 302 438 14
4 11.0 8.9 12.7 7.3 6.9 7.8 149 110 236 516 300 691 539 436 717 9
5 13.9 8.2 17.7 7.5 6.9 8.0 119 60 285 332 236 408 290 248 328 15
6 13.9 7.0 16.7 7.4 6.8 7.7 106 48 208 379 302 507 340 275 395 14
7 18.5 13.0 25.0 7.5 7.2 7.7 185 -30 630 590 361 665 541 377 625 8
8 14.1 11.0 18.0 6.3 6.1 6.6 126 66 207 366 341 387 267 229 323 11
9 18.4 13.8 21.1 7.7 7.5 7.9 171 124 284 479 446 528 416 380 449 4
10 22.4 21.8 22.9 7.5 7.5 7.7 146 76 202 407 359 432 414 398 441 4
11 17.7 17.0 18.5 7.2 7.1 7.3 247 166 315 1,028 946 1,109 963 912 1,014 4
12 16.2 15.7 17.2 7.7 7.4 8.0 166 136 211 1,597 1,436 1,801 1,531 1,444 1,634 4
13 12.8 7.0 17.0 7.7 7.3 8.1 143 93 264 411 370 528 332 206 435 15
14 13.7 9.5 16.6 7.3 7.1 7.6 145 109 233 710 677 758 594 525 706 11
15 18.9 16.4 23.1 7.1 7.0 7.3 99 29 190 992 876 1,133 889 845 929 3
16 13.3 8.3 19.0 7.6 7.2 8.1 115 56 253 580 365 720 493 414 602 15
17 20.7 20.1 21.3 7.7 7.3 8.1 18 -115 142 577 529 661 520 474 578 4
18 17.9 17.8 17.9 7.8 7.6 7.9 108 70 146 1,084 957 1,210 968 905 1,032 2
19 16.7 16.0 17.4 7.2 7.2 7.3 158 145 171 1,055 1,005 1,105 949 876 1,022 2
20 19.9 18.0 21.7 7.4 7.3 7.6 168 149 187 919 900 937 746 691 801 2
21 19.8 19.5 20.0 7.4 7.2 7.5 161 158 164 415 413 416 355 342 367 2
22 18.0 18.0 18.0 7.3 7.2 7.3 164 155 173 426 422 430 363 353 373 2
23 15.4 13.0 19.6 7.5 7.1 8.1 200 130 285 282 219 321 285 263 304 3
EC electrical conductivity at 25�C, TDS total dissolved solids, n number of collected samples
Environ Geol (2009) 57:885–898 889
123
Tab
le2
Mea
n,
min
imum
and
max
imum
val
ues
of
the
maj
or
chem
ical
const
ituen
ts
No.
Na
KM
gC
aF
Cl
Br
NO
3S
O4
HC
O3
Mea
nM
in.
Max
.M
ean
Min
.M
ax.
Mea
nM
in.
Max
.M
ean
Min
.M
ax.
Mea
nM
in.
Max
.M
ean
Min
.M
ax.
Mea
nM
in.
Max
.M
ean
Min
.M
ax.
Mea
nM
in.
Max
.M
ean
Min
.M
ax.
152.6
47.8
58.9
2.6
1.7
3.1
17.3
16.3
19.4
76.4
66.9
83.6
0.4
0.2
1.0
81.4
70.9
97.8
0.4
0.1
0.9
1.9
0.0
3.8
29.2
25.0
40.3
283
235
302
228.1
26.2
29.7
2.3
1.7
3.1
11.6
11.1
12.2
44.9
42.7
48.6
0.2
0.2
0.2
56.0
54.9
56.4
0.2
0.2
0.2
1.6
0.0
4.3
20.5
19.5
22.1
149
143
156
316.8
14.9
19.1
0.5
0.0
1.2
3.3
2.9
3.6
71.3
60.7
89.0
0.2
0.1
0.4
28.2
23.0
32.3
0.1
0.0
0.2
0.7
0.0
3.8
15.3
11.5
19.7
211
189
268
418.7
12.9
27.6
1.0
0.0
3.4
5.8
4.5
8.3
117.0
99.8
153.3
0.1
0.0
0.2
25.8
21.6
34.0
0.1
0.0
0.2
2.0
0.0
5.0
43.2
28.3
64.4
326
268
421
510.5
8.5
14.4
0.9
0.0
1.6
3.2
1.8
6.8
59.7
52.3
65.5
0.3
0.1
0.6
17.4
15.6
19.1
0.1
0.0
0.2
4.7
3.0
7.5
8.8
7.7
11.0
184
159
201
69.7
7.1
13.8
0.7
0.0
1.6
2.8
1.6
4.0
74.9
65.7
83.2
0.3
0.2
0.6
16.9
13.8
27.7
0.1
0.0
0.2
4.1
2.4
9.5
8.4
6.7
11.0
222
177
244
731.8
21.2
36.1
2.3
2.0
2.7
13.0
9.7
14.6
95.2
69.7
108.2
0.4
0.2
0.6
37.8
33.7
40.1
0.2
0.0
0.6
1.4
0.0
2.5
55.3
33.1
65.3
303
207
354
828.6
26.0
32.2
2.3
1.4
2.7
9.2
7.3
12.0
34.4
31.3
38.9
0.5
0.2
1.0
43.9
38.3
48.2
0.4
0.1
0.9
2.3
0.6
5.7
30.7
26.4
40.8
114
98
140
920.0
19.3
21.4
1.9
0.2
2.7
19.3
18.1
21.1
64.0
59.5
67.8
1.0
1.0
1.1
30.0
25.9
34.6
0.1
0.1
0.1
4.8
2.6
7.7
26.6
25.0
30.3
249
229
262
10
16.4
14.0
17.7
2.4
2.1
3.0
29.5
27.8
31.7
48.7
46.5
51.7
2.2
2.1
2.3
20.5
18.7
24.5
0.5
0.1
1.6
2.9
1.2
5.4
24.7
23.4
25.6
266
262
278
11
69.6
53.6
78.4
2.0
0.7
3.8
26.8
25.0
29.0
161.9
156.3
168.5
0.5
0.3
0.7
83.4
80.5
86.1
0.5
0.4
0.7
35.7
32.8
39.7
126.1
123.0
127.9
457
439
479
12
376.9
354.3
420.4
12.2
10.6
13.5
25.0
20.7
31.3
35.2
30.6
40.3
1.2
0.1
1.9
124.9
109.2
143.0
0.6
0.4
0.7
3.4
0.0
8.1
196.6
192.1
200.0
755
726
775
13
10.9
8.6
12.4
1.1
0.6
1.6
3.1
2.3
4.5
70.8
38.3
91.0
0.3
0.0
0.6
18.9
16.7
26.8
0.2
0.0
1.6
1.7
0.6
4.8
6.7
4.8
10.8
219
134
281
14
38.1
32.4
48.5
3.0
2.1
4.3
22.9
21.4
24.1
94.4
85.2
107.6
0.5
0.0
0.8
43.1
35.5
56.7
0.3
0.1
0.6
2.6
0.0
5.2
170.9
156.6
226.2
218
192
232
15
105.3
91.0
117.5
4.2
3.4
5.2
26.2
24.6
28.7
104.9
100.8
107.4
0.2
0.0
0.3
42.1
40.4
43.8
0.2
0.2
0.2
3.0
0.0
5.3
197.0
188.3
202.4
406
397
418
16
43.6
33.1
53.6
2.5
0.8
4.1
14.5
13.0
16.8
74.4
68.1
85.8
0.4
0.0
0.6
42.9
32.3
52.8
1.2
0.0
9.3
3.8
0.0
7.9
102.0
83.6
127.3
208
183
244
17
92.6
82.1
113.3
4.0
2.9
6.1
14.0
11.5
20.4
32.3
19.0
40.5
1.0
0.9
1.1
36.5
32.4
46.1
0.2
0.1
0.3
5.5
4.0
6.9
36.6
34.6
41.3
297
287
302
18
190.6
186.2
195.1
25.3
23.3
27.4
20.1
18.0
22.1
43.6
39.5
47.7
0.5
0.3
0.7
45.3
42.2
48.4
0.1
0.0
0.2
12.9
10.7
15.0
268.5
255.0
281.9
362
330
394
19
59.4
55.2
63.5
10.8
10.3
11.3
17.2
16.5
17.9
176.7
169.1
184.3
0.2
0.2
0.2
111.5
104.1
118.9
0.1
0.0
0.3
64.4
60.6
68.2
174.0
157.4
190.7
334
302
366
20
64.2
62.0
66.3
21.0
20.1
21.8
12.3
11.2
13.3
119.1
108.5
129.7
0.2
0.2
0.2
106.4
105.7
107.0
0.2
0.0
0.4
174.0
143.5
204.6
80.9
75.4
86.4
168
165
171
21
14.5
14.3
14.7
1.3
1.3
1.4
22.5
22.0
22.9
46.5
46.1
47.0
1.4
1.4
1.5
18.8
18.4
19.1
0.0
0.0
0.0
4.0
3.8
4.1
21.2
21.0
21.5
224
214
235
22
17.7
17.5
17.9
3.3
2.6
4.0
22.7
22.5
22.9
46.3
45.8
46.8
1.3
1.3
1.4
18.5
18.4
18.6
0.0
0.0
0.0
2.8
2.8
2.9
22.9
22.6
23.2
227
220
235
23
9.5
8.5
10.1
0.8
0.8
0.8
4.1
4.0
4.4
59.3
55.9
65.9
0.1
0.1
0.2
17.8
17.0
18.4
0.0
0.0
0.1
3.8
1.9
5.7
10.6
9.6
12.0
179
165
186
All
the
conce
ntr
atio
ns
are
expre
ssed
inm
g/l
890 Environ Geol (2009) 57:885–898
123
Group B includes 10 water points: two of them (nos. 1
and 2) are located on the northern part of Rocca Busambra,
whereas nos. 7, 8, 14, 15 and 16 are outflows to the north of
the dorsal at the flyschoid deposits; spring nos. 19 and 20
issue from the western zone, at the boundary between the
Numidian Flysch and the marls of the ‘‘Marne di S. Cip-
irrello’’ formation, and finally water point no. 11 lies in
proximity of Pizzo Chiarastella (north-eastern sector).
The mean TDS value ranges between 267 mg/l (no. 8)
and 963 mg/l (no. 11). Such a wide range in the TDS
values suggests the presence of hydrogeological circuits
having different lengths and/or residence times.
The average chemical composition (Ca [ Na–HCO3 C
SO4 and Ca [ Na–HCO3 C Cl types) of the latter group of
samples highlights two main components: a Ca–HCO3
component and an additional Na–SO4–Cl component.
While it seems unquestionable that the Na–SO4–Cl
component mainly reflects the interaction with the Numi-
dian Flysch deposits (Favara et al. 2000) as they outflow
from the quartz–arenites, it is not clear about the origin of
the Ca–HCO3 component. There are two possibilities: cal-
cium and bicarbonate might originate from the dissolution
of the limestone forming the dorsal or from the calcite
cement within the quartz–arenites. The former process is
evident in sample no. 7 (TDS = 541 mg/l), the chemical
signature of which leans towards A group composition, and
probably indicates a mixing between group A and group B
waters. On the contrary, very low TDS value (267 mg/l) in
sample no. 8 suggests that it exclusively drains the quartz–
arenites and consequently the carbonate component derives
from the dissolution of carbonate cement.
The three remaining water points (wells nos. 12, 17 and
18), which are not included either in group A or in group B,
show singular chemical characteristics. In the Langelier–
Ludwig diagram, they fall in the fields of sodium–potas-
sium–bicarbonate (wells nos. 12 and 17) and sodium–
potassium–chloride–sulphate (no. 18) type waters, and
differ from the other samples because of their relatively
high content in Na and K. The enrichment in the alkaline
elements at wells 17 and 18 could be caused by the dis-
solution of glauconite as suggested by the presence of
significant thicknesses of the ‘‘Calcareniti di Corleone’’
formation emerging in the vicinity of the wells.
At well no. 12, located to the north-east of Rocca Bu-
sambra, the alkaline elements prevail over the earth-
alkaline metals, probably as a result of cation exchange
processes between clay minerals and water, in accordance
with the following reaction:
Na - Clay + 1/2Caþþ + 1/2Mgþþ
¼ 2Naþ + CaMg - Clay
Moreover, this well has the highest TDS value (1,531 mg/l)
suggesting a longer residence time in the aquifer. High
alkalinity content (755 mg/l) points to the dissolution of an
external source of CO2 into the water.
The cation ternary diagram (Fig. 5a) highlights that
some samples belonging to group A and located to the west
of the dorsal are progressively enriched in magnesium.
Moreover, these waters show a positive correlation
between Mg2+ and F- contents (Fig. 6) suggesting that the
magnesium and fluoride in these waters have the same
origin. This enrichment could derive from the dissolution
of hydrothermal fluorite, which has often been found in the
Triassic dolostone belonging to the Trapanese domain
(Bellanca et al. 1990).
In the HCO3–SO4–Cl ternary diagram (Fig. 5b), the
waters belonging to group A fall very close to the HCO3
vertex, whereas B group waters are aligned along two
evolution trends: towards the Cl vertex and towards the
sulphate corner. This differentiation could be the result of a
mineralogical complexity of the flyschoid deposits (Alaimo
and Ferla 1975), where sulphur-rich minerals (sulphides
and sulphates) and Cl-bearing compounds have been
found.
Chemical equilibrium
During flow, groundwater tends to dissolve the rocks
forming the aquifer in which it circulates, as long as
chemical equilibrium is attained. The saturation index (SI)
is a parameter that describes whether a solution is saturated
(SI = 0), oversaturated (SI [ 0) or undersaturated (SI \ 0)
in respect of the mineral in question. It is defined as the
Fig. 4 Langelier–Ludwig classification diagram
Environ Geol (2009) 57:885–898 891
123
logarithm of the ratio between the ion activity product
(I.A.P.) for a given mineralogical phase and the equilib-
rium constant of its solubility product (Ksp) as follows:
SI ¼ log I.A.P.�
Ksp
� �:
The saturation state with respect to the main carbonate
minerals was applied successfully to distinguish between
prevailing limestone aquifers and dolostone aquifers. For
this reason, the PHREEQC computer program (Parkhurst
and Appelo 1999) was used to evaluate the saturation
indexes of the group A water points in respect of pure
calcite (SIc), dolomite (SId) and fluorite (SIf) (Table 3).
The arrangement of the water points in the SIc–SId
diagram (Fig. 7) provides us with two important insights.
All the waters taken into consideration are nearly saturated
with respect to calcite (-0.3 \ SIc \ 0.4), thus confirming
that the dissolution of limestone is the main water–rock
interaction process. The samples show a wider range of
saturation with respect to dolomite. Springs nos. 6, 5 and
23, located on the south-east flank of Rocca Busambra, are
strongly undersaturated (SId \ -1), suggesting that they
prevalently drain through Mesozoic limestone. The
remaining water points (nos. 3, 4, 9, 10, 13, 21 and 22) are
nearly saturated or saturated with respect to dolomite, thus
suggesting that the Mg contents is probably controlled
mainly by the dissolution of the Mg-rich limestone and/or
dolostone (Trias–Lias in age), which characterise the bot-
tom part of the carbonate sequence.
The hypothesis that these springs are fed by deeper
hydrogeological circuits also seems to be confirmed by the
arrangement of the samples in the SId–SIf diagram (Fig. 8).
As fluorite is a very common hydrothermal mineral in the
Triassic dolostone of the Trapanese domain (Bellanca et al.
1990), all the samples are undersaturated with respect to
fluorite, except for samples nos. 9, 10, 21 and 22, which are
nearly saturated.
Fig. 5 Triangular plots: a Ca–Na + K–Mg; b SO4–HCO3–Cl
Fig. 6 Mg versus F contents in the group A samples
Table 3 Saturation indexes with respect to pure calcite (SIc), dolo-
mite (SId) and fluorite (SIf), calculated only for group A samples
Number SI Calcite SI Dolomite SI Fluorite
3 0.4 -0.4 -2.1
4 0.2 -0.7 -2.3
5 0.0 -1.1 -1.9
6 0.0 -1.3 -1.9
9 0.4 0.5 -1.0
10 0.2 0.4 -0.5
13 0.3 -0.6 -1.9
21 -0.2 -0.4 -0.8
22 -0.3 -0.6 -0.8
23 0.0 -1.0 -2.7
892 Environ Geol (2009) 57:885–898
123
Isotope composition
Precipitation
The isotopic composition of precipitation in the Rocca
Busambra area is reported in Table 4 together with the
weighted average values. The dD and d18O values range
from -60% to -16% and from -9.2% to -2.7%,
respectively, at the PC rain gauge, and between -70% and
-13% and between -10.9% and -2.6%, respectively, at
the PM station. According to the temperature-dependent
isotope fractionations occurring during water evaporation/
droplet condensation processes (the so-called ‘‘seasonal
effect’’), rainwater shows more negative isotope values
during the cold months than during the warm season, when
precipitation is enriched in heavy isotopes, although there
are some exceptions.
The samples collected in March and October at both
stations show more positive dD and d18O values than those
expected, given the seasonal trend; this coincides with
monthly amounts lower than the general trend. On the
contrary, the rainwater isotope composition of the sample
collected in April at PC station shows the most negative
value. This anomalous value is most probably related to a
precipitation event that occurred under peculiar environ-
mental conditions (i.e., condensation temperature lower
than average monthly ones).
The stable isotope composition of the precipitation was
plotted on the dD–d18O diagram (Fig. 9). The meteoric
water line (MWL), as defined by Craig (1961), and the
MMWL regarding Mediterranean precipitations (Gat and
Carmi 1970) are also reported on the same diagram. Most
of the samples collected monthly fall within these two
reference lines. The best fit line for these points is as
follows:
dD ¼ 6:4� d18Oþ 5:5
which represents the local MWL (LMWL).
Fig. 8 SIf versus SId plot. Samples belonging to the group A are
reported. The dotted lines represent the range of saturation (±0.5)
Table 4 Isotopic composition of precipitation in the Rocca Busam-
bra area, collected by two rain gauges: PC (800 m a.m.s.l.) and PM
(530 m a.m.s.l.)
Month PC PM
dD d18O mm dD d18O mm
December 2000 -48 -8.9 111 -36 -7.1 48
January 2001 -34 -6.3 121 -70 -10.9 46
February 2001 ND ND ND -42 -7.6 40
March 2001 -23 -5.3 33 -13 -2.9 16
April 2001 -60 -9.2 58 -43 -6.8 40
May 2001 -16 -2.7 65 -15 -2.8 42
June 2001 ND ND ND -15 -2.6 19
July 2001 -17 -3.5 9 -17 -4.2 3
August 2001 -45 -8.5 44 ND ND ND
September 2001 -39 -7.5 48 -40 -6.7 74
October 2001 -33 -6.1 48 -22 -4.6 44
November 2001 -48 -8.5 127 -44 -7.1 82
Weighted average -40 -7.2 -38 -6.5
Fig. 7 SIc versus SId plot. Samples belonging to the group A are
reported. The dotted lines represent the range of saturation (±0.5)
Environ Geol (2009) 57:885–898 893
123
Because rainfall is not uniformly distributed throughout
the year, volume-weighted mean values were computed as
follows:
dwm ¼X12
i¼1
qi � di � q�1tot
where qi represents the amount of rainfall collected during
the i-esime month, d is the isotopic composition (both
hydrogen and oxygen) and qtot is the annual rainfall.
The weighted mean isotope values computed show a
progressive negativization as altitude increases (Fig. 10).
The linear regression through these data points provides the
vertical isotopic gradient for this area, which quantifies the
so-called ‘‘altitude effect’’ on the isotopic composition of
rain. The obtained value is about 0.26%/100 m, which is
slightly higher than that previously determined for north-
west Sicily (0.2%/100 m; Hauser et al. 1980).
Groundwater
The maximum, minimum and mean values of the isotopic
composition of the water collected from the springs and
wells are reported in Table 5. The mean d18O value ranges
from -8.0% (sample no. 4) to -6.4% (samples nos. 12
and 19), whereas the dD values range from -45% (sam-
ples nos. 5, 6 and 8) to -39% (sample no. 12).
In the dD–d18O diagram (Fig. 11), the groundwater
samples have been plotted together with the LMWL and
the weighted mean isotope values of precipitation at both
stations. Almost all the samples collected lie along the
Fig. 10 d18O values of groundwater versus their respective elevation
expressed in m a.m.s.l
Table 5 Isotopic composition of groundwater samples
Number dD d18O Altitude
(m a.m.s.l.)Mean Min. Max. Mean Min. Max.
1 -43 -45 -40 -7.9 -8.2 -7.7 835
2 -43 -44 -42 -7.8 -7.9 -7.7 940
3 -43 -45 -40 -7.9 -8.1 -7.7 1,010
4 -44 -47 -41 -8.0 -8.3 -7.5 910
5 -45 -48 -41 -7.9 -8.2 -7.6 850
6 -45 -48 -41 -7.8 -8.0 -7.7 960
7 -44 -46 -41 -7.8 -8.0 -7.6 750
8 -45 -48 -42 -7.7 -7.9 -7.5 595
9 -42 -44 -40 -7.6 -7.7 -7.3 385
10 -44 -45 -42 -7.8 -7.8 -7.7 370
11 -41 -43 -39 -6.8 -7.0 -6.7 520
12 -39 -43 -37 -6.4 -6.5 -6.3 580
13 -44 -47 -42 -7.7 -8.0 -7.5 980
14 -44 -47 -39 -7.8 -7.9 -7.6 740
15 -43 -45 -42 -7.7 -7.8 -7.7 775
16 -43 -47 -39 -7.7 -7.8 -7.5 640
17 -41 -42 -41 -7.6 -7.7 -7.5 570
18 -42 -43 -40 -7.1 -7.1 -7.1 585
19 ND ND ND -6.4 -6.8 -6.1 570
20 ND ND ND -6.5 -6.6 -6.3 540
21 ND ND ND -7.8 -7.9 -7.8 380
22 ND ND ND -7.9 -8.0 -7.9 375
23 -44 -44 -44 -7.9 -8.0 -7.7 860
Mean, minimum and maximum dD and d18O values are expressed in
d values
Fig. 9 dD–d18O diagram of the rain waters monthly collected in the
Rocca Busambra area
894 Environ Geol (2009) 57:885–898
123
LMWL line, which underlines the fact that groundwater is
meteoric in origin and not affected by secondary postfor-
mation processes. All the samples show more negative dD
and d18O values than those of weighted mean rainwater and
fall within a narrow range (d18O = - 7.8%o ± 0.2;
dD = - 43%o ± 2), but only three samples (nos. 11, 12
and 18) showing values in the same range of those
regarding weighted mean precipitation.
Given that the isotopic composition of rainwater
becomes more negative as elevation increases, groundwa-
ter with d18O values lower than those of weighted mean
rainwater could be related to recharge areas located at
higher elevations. By solving the vertical isotopic gradient
in respect of elevation (Q), the following equation was
obtained:
Q = � 385� d18O � 1977
This relationship allows us to estimate the mean elevation
of the main recharge areas when the isotopic composition
of groundwater is known.
In Fig. 10, the d18O values of groundwater are reported
against their respective elevation. It is possible to observe
that almost all the water discharges have an d18O value of
-7.8% ± 0.2, which corresponds to a recharge area at an
elevation of 1,025 ± 75 m a.m.s.l. As far as the remaining
samples are concerned (nos. 11, 12, 18, 19 and 20), the
d18O values that fall between -7.2% and -6.4% corre-
spond to a feeding area from 500 to 800 m a.m.s.l.
Almost all the samples show isotope values that are
fairly constant over time as they have a limited d18O annual
variability (D18Od18Omin–d18Omax \ 0.5 d%) lower than
that of rainwater (D18O & 4 d%) during the period of
effective meteoric (i.e., from October to March). The
annual variability in the composition of groundwater iso-
topes allowed to distinguish between limited and huge
aquifers hosted in the Rocca Busambra area.
Isotope values fairly constant over time imply that vol-
umetrically extended aquifers do exist and that they are
capable of modulating the variations in the isotopic com-
positions induced by local meteoric recharge. On the
contrary, springs showing a d18O annual variability[0.5%seem to be the result of the limited volume of their
respective aquifers. In fact, the flow rate of these springs
changes drastically throughout the year until the springs
themselves actually disappear, as is the case of spring no. 4.
Model of groundwater circulation
Based on the chemical and isotopic compositions of the
waters collected, a circulation model for the groundwater
in the Rocca Busambra area is proposed here. Two main
recharge zones have been inferred on the basis of the stable
isotope signature. The first one is located between 500 and
800 m a.m.s.l., whereas the second one has an average
elevation of about 1,025 ± 75 m a.m.s.l. The first recharge
area corresponds to the main outcroppings of the quartz–
arenites of the Numidian Flysch and the terrigenous
deposits (sands and conglomerates) of the Terravecchia
Formation surrounding the carbonate dorsal.
The highest recharge zone perfectly coincides with the
topographic and hydrogeologic setting of the Rocca Bu-
sambra carbonate massif. In accordance with the
sedimentary sequence, three main flow-paths have been
recognized within this carbonate relief (Fig. 12).
Along the south-eastern orographic side of Rocca Bu-
sambra, groundwater circulation occurs in short circuits
predominantly hosted within the Triassic limestone. The
springs that outflow in this area (nos. 5, 6 and 23) show
very low salinity values, high Ca/Mg ratios and the
achievement of a saturation state with respect to calcite
while they are undersaturated with respect to dolomite.
Along the north and north-eastern flanks of the dorsal,
springs are mainly fed by hydrogeological circuits hosted
within that portion of the carbonate succession where Mg-
rich limestone is dominant. Carbonate waters (nos. 3, 4 and
13) that drain from this flank show intermediate Ca/Mg
ratios, which result as being close to saturation state with
respect to both calcite and dolomite. Seven water points
belonging to group B issue from this flank. The discharges,
which outflow from the quartz–arenites, are typical contact
springs that drain from the carbonate rocks overlying the
Numidian Flysch.
Water points 9, 10, 21 and 22, which drain from the
western flank, are chemically different from the other waters
of group A, thus reflecting a different hydrogeological set-
ting. These springs show a progressive increase in their
magnesium and fluoride contents as they flow westward.
This leads to low Ca/Mg ratios (close to 1 at spring 10) and
Fig. 11 dD–d18O diagram of the groundwater samples
Environ Geol (2009) 57:885–898 895
123
saturation with respect to both calcite and dolomite and also
to almost complete saturation with respect to fluorite (spring
no. 10). The circulation of these waters is thought to be deep
enough to reach the Triassic dolostone at the bottom of the
Trapanese domain, where deposits of hydrothermal fluorite
have been found (Bellanca et al., 1990). These findings seem
to be indicative of hydraulic communication between the
central part of Rocca Busambra and the buried carbonate
structures, emerging in limited outcroppings on the western
portion of the study area.
Such a chemical evolution could also be explained by
considering other relieves as being alternative recharge
areas. These relieves, situated in the neighborhood of the
study area, should have similar topographic and geological
characteristics to those of the Rocca Busambra dorsal. For
instance, M. Kumeta (1,233 m a.m.s.l.), the nearest car-
bonate relief that extends for about 20 km2, consists mainly
of the same carbonate succession of the Rocca Busambra
dorsal (Fig. 12).
The chemical features and isotope signatures of the
meteoric water infiltrating through M. Kumeta and flowing
southwards within the carbonate structures, buried below
the impermeable cover, should be comparable to the waters
infiltrating into the Rocca Busambra dorsal area and
flowing westwards at depth. Moreover, it is reasonable to
presume that both the Rocca Busambra and the M. Kumeta
carbonate reliefs contribute to the feeding of these springs.
Quality of the waters and their potential use
The quality of the groundwater and, consequently, its
potential use either as drinking water or irrigation water has
been evaluated on the basis of chemical analyses. To
evaluate whether or not these waters could be used for
drinking purposes, the chemical data was compared with
the maximum permissible concentrations indicated in the
WHO guidelines (World Health Organization 2004) and
reported in Table 6). Nearly all of the analyzed samples
fall within the range of drinkable waters, with the excep-
tion of a few whose NO3- (nos. 19 and 20), F- (no. 10) and
Na+ (no. 12) contents were too high.
While the excess of F- and Na+ can probably be
referred to natural water–rock interaction processes, high
nitrate contents have to be related to anthropic pollution. In
fact, when fertilizers are used in agriculture, often a part of
the nitrogen is not assimilated by the plants; so, it goes into
the aquifers thereby lowering the quality of the water.
To evaluate whether water is suitable for agricultural
purposes, some quality requirements must be satisfied. The
parameters that were taken into consideration are as fol-
lows: (1) Salinity: reported in terms of electrical
conductivity (EC); (2) Sodium adsorption ratio (SAR):
related to the soil’s ability to adsorb sodium; (3) Residual
sodium carbonate (RSC): it indicates the degree of
Fig. 12 Sketch map of
groundwater circulation
in the studied area
Table 6 Limit values for drinking water, extracted by WHO guide-
lines (World Health Organization 2004)
Parameter Limit values (mg/l)
Clorides 250.0
Sulphates 500.0
Sodium 200.0
Nitrates 50.0
Fluoride 1.5
896 Environ Geol (2009) 57:885–898
123
precipitation of calcium and magnesium in the soils. The
latter parameter is calculated as the difference between the
concentrations of the carbonate species (CO3 + HCO3)
and the concentration of earth alkaline elements
(Ca + Mg).
The classification diagram (Fig. 13), proposed by Wil-
cox (1955), couples both the conductivity (CE) and the
SAR values. Almost all the waters collected were sub-
stantially suitable for irrigation, as they fall within the
C2S1 and C3S1 fields. Both these fields indicate low
hazard of soil alkalinization and medium–high hazard of
accumulation of salt in the soil. In particular, the carbonate
groundwater (group A) was of good quality, as it falls
solely in the C2S1 field. On the contrary, the group B
waters plot along a trend from C2S1 to C3S1 fields, thereby
highlighting a progressive worsening in the quality of the
water as the length of the circuits and/or the residence
times increased.
The other water points, which are not included in groups A
and B, plot into three fields (C2S1, C3S2 and C3S3). Based
on the Wilcox diagram, sample no. 12 is harmful for irriga-
tion and agricultural activity. Moreover, it is the only sample
that exceeds the maximum RSC values (2.5 mequiv./l;
Mckee and Wolf 1963).
Conclusions
The groundwater circulating in and around the Rocca Bu-
sambra carbonate dorsal was arranged in two main groups:
• Ca C Mg–HCO3 (group A)
• Ca [ Na–HCO3 C SO4 and Ca [ Na–HCO3 C Cl
(group B)
The first one reflects the dissolution of the limestone and
dolostone forming the Rocca Busambra relief. The second
group highlights two main components: a prevailing Ca–
HCO3 component originating from the dissolution of car-
bonate minerals and an additional Na–SO4 or Na–Cl
component that reflects interaction with the Numidian
Flysch deposits (Favara et al. 2000).
Three waters (samples nos. 12, 17 and 18) showed
peculiar chemical features and therefore they are not
included either in the group A or in the group B waters.
These samples differ from the group A and group B waters
because of their relatively high content in Na and K. The
enrichment in alkaline elements seems to be due to the
dissolution of glauconite and/or to the cation exchange
processes between clay minerals and water.
The water isotope signature indicated that the ground-
water is of meteoric origin and is not affected by secondary
postformation processes. Based on the 18-Oxygen vertical
isotope gradient (0.26 d%/100 m) computed from the
isotope composition of the rainwater collected at two rain
gauges, two main recharge zones were inferred. The first
one has an average elevation of about 1,025 ± 75 m
a.m.s.l., which coincides with the topographic setting of the
Rocca Busambra carbonate massif. The second one, loca-
ted between 500 and 800 m a.m.s.l., corresponds to the
main outcroppings of the Numidian Flysch deposits and the
Terravecchia Formation.
The water resource in the studied area, evaluated
through a preliminary water budget, was inferred to be in
the order of about 2–3 9 107 m3 year-1. As expected, the
Rocca Busambra massif is the main infiltration area of the
aquifers feeding all the water points belonging to group A
(Ca C Mg–HCO3-type) and almost all those belonging to
group B.
Three main flow-paths were recognized on the basis of
the sedimentary sequence within this carbonate relief:
• Along the south-eastern side where limestone prevails
(very low salinity, high Ca/Mg ratios, SIc = 0 and
SId \ 0)
• Along the north and north-eastern flank of the dorsal,
where Mg-rich limestone are dominant (carbonate
waters had intermediate Ca/Mg ratios, SIc = 0,
SId = 0). This flow-path also involves seven group B
springs, which are typical contact springs that drain
from the carbonate rocks overlying the Numidian
Flysch
• Along the western flank where Triassic dolostone and
hydrothermal fluorite deposits were inferred to be
found at depths beneath the covering deposits. Along
this flow-path, groundwater shows a progressiveFig. 13 Wilcox classification diagram
Environ Geol (2009) 57:885–898 897
123
increase in Mg and F, the lowest Ca/Mg ratios, SIc = 0,
SId = 0 and SIf ? 0. A chemical evolution of this kind
could also be explained by considering other relieves
having similar topographic and geological characteris-
tics to those of the Rocca Busambra dorsal as being
alternative recharge areas.
A comparison with the WHO guidelines for drinking
waters highlighted that nearly all the samples are suitable
for drinking use, with the exception of four samples in
which the NO3-, F- and Na+ contents exceeded the limits.
High NO3- contents have to be probably referred to the use
of fertilizers, while high F- and Na+ contents exceeding
the WHO limits result from water–rock interaction pro-
cesses. Almost all the waters collected had a low hazard
risk of soil alkalinization and a medium–high hazard risk of
salt accumulation in the soil, and are therefore suitable for
irrigation with the only exception of sample no. 12.
References
Agate M, Basilone L, Catalano R, Franchino A, Merlini S, Sulli A
(1998) Ipotesi sulla condizione strutturale della Rocca Busambra
(Hypothesis on the structural setting of Rocca Busambra dorsal).
In: Proceedings of the 79th National Congress of the ‘‘Societa
Geologica Italiana,’’ Palermo, Italy, 21–23 September 1998, pp
71–78
Alaimo R, Ferla P (1975) Natrojarosite e thenardite, solfati idroter-
mali ricchi in sodio, nelle argille variegate con dickite di
Scillato–Caltavuturo (Sicilia) [Natrojarosite and thenardite, Na-
rich sulphate hydrothermal minerals embedded within the dickite
clay of Scillato–Caltavututro (Sicily)]. Period Mineral 44:227–
243
Bellanca A, Dongarra G, Neri R, Parello F (1990) Geochemistry of
ground waters in carbonate rocks hosting fluorite mineraliza-
tions, northwestern Sicily. Acque Sotterranee IV:47–53
Catalano R, D’Argenio B (1982) Schema geologico della Sicilia
(Geological scheme of Sicily). In: Catalano R, D’Argenio B
(eds) Guida alla geologia della Sicilia occidentale. Societa
Geologica Italiana, Palermo, pp 126–135
Celico P (1986) Valutazione delle risorse e delle riserve idriche
sotterranee. In: Prospezioni idrogeologiche (Evaluation of
groundwater resources and reserves), Cap. VIII, vol 2. Liguori
Editore, Napoli, pp 13–185
Coleman ML, Sheppard TJ, Duhrham JJ, Rouse JE, Moore GR (1982)
Reduction of water with zinc for hydrogen isotopic analysis.
Anal Chem 54:993–995
Craig H (1961) Isotopic variations in meteoric waters. Science
133:1702–1703
Dooge JCI (1977) Problems and methods of rainfall-runoff modelling.
In: Ciriani TA, Maione U, Wallis JR (eds) Mathematical models
for surface water hydrology. Wiley, New York, pp 71–108
Favara R, Grassa F, Valenza M (2000) Hydrochemical evolution and
environmental features of Salso River catchment, central Sicily
(Italy). Environ Geol 39:1205–1215
Gat JK, Carmi I (1970) Evolution of isotopic composition of
atmospheric waters in the Mediterranean Sea area. J Geophys
Res 75:3039–3040
Langelier WF, Ludwig HF (1942) Graphical methods for indicating
the mineral character of natural waters. J Am Water Works
Assoc 34:335–352
Hauser S, Dongarra G, Favara R, Longinelli A (1980) Composizione
isotopica delle piogge in Sicilia. Riferimenti di base per studi
idrogeologici e relazioni con altre aree mediterranee (Rainwater
isotope composition of Sicily. A reference for hydrogeological
studies and relationships with other Mediterranean areas). Rend
Soc Ital Mineral Petrol 36(2):671–680
Lentini F, Carbone S, Catalano S (1994) Main structural domains of
the Central Mediterranean Region and their Neogene tectonic
evolution. Boll Geof Teor Appl 36:103–125
Mckee JE, Wolf HW (1963) Water quality criteria. California State
Water Quality Control Board, Sacramento, 548 pp
Parkhurst DL, Appelo CAJ (1999) User’s guide to PHREEQC—a
computer program for speciation, batch-reaction, 1D-transport
and inverse geochemical calculation. US Geological Survey
Water-Resources Investigation Report 99-4259, 312 pp
Roure F, Howell DG, Muller C, Moretti I (1990) Late Cenozoic
subduction complex of Sicily. J Struct Geol 12(2):259–266
Thiessen AH (1911) Precipitation average for large areas. Mon
Weather Rev 39:1082–1089
Thornthwaite CW (1948) An approach towards a rational classifica-
tion of climate. Geogr Rev 38:55–94
Turc L (1955) Le bilan d’eau des sols. Relations entre les
precipitations, l’evaporation et l’ecoulement (Soil water bal-
ances: relation between precipitation, evaporation and runoff).
Ann Agron 5:491–596
Vitale FP (1995) Il segmento sicano della catena sud-tirrenica: bacini
neogenici e deformazione attiva (The ‘‘sicano’’ segment of the
south-tyrrhenian chain: neogenic basins and active deforma-
tions). Stud Geol Camerti Spec Vol (2):491–507
World Health Organization (2004) Guidelines for drinking-water
quality, vol 1: recommendations, 3rd edn. WHO, Geneva
Wilcox LV (1955) Classification and use of irrigation waters. US
Department of Agriculture Circular No. 969, 19 pp
898 Environ Geol (2009) 57:885–898
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