Groundwater Quality on the Adriatic Karst Island of Mljet (Croatia) and Its Implications on Water Supply
Table 1
Physicochemical parameters and major ion composition of waters from localities on the island of Mljet in different seasons (values in bold italics are exceeding maximum values for drinking water; localities marked by an asterisk are not a part of the water supply system).
Sampling point
Elevation (m a.s.l.)
EC (μS/cm)
T (°C)
pH
Ca2+(mg/l)
Mg2+(mg/l)
Na+(mg/l)
K+(mg/l)
HCO3-(mg/l)
Cl-(mg/l)
SO42-(mg/l)
NO3-(mg/l)
MIN 2005
Spilja intake structure—Sobra
4
2,860
15.7
7.4
153
53.2
329
9.8
399
660
90
1.9
Blato wells
28
8,120
15.9
7.66
160
117
1,574
76
410
2,240
300
0
Slatina
0.5
6,930
22.1
7.5
118
111
1,096
70
450
1,950
190
0
Prožurska blatina
0.5
32,000
26.1
7.79
75
200
5,582
102
310
9,640
1,600
0
MAX 2006
Spilja intake structure—Sobra
4
1,527
15.7
7.61
66.4
20.9
185
3.1
215
340
50
0
Sobranska blatina
3
1,529
16.2
7.82
66.4
20.9
195
3.1
215
380
51
0
Blato wells
28
877
14.7
7.59
76.8
25.4
46
2.1
285
86
43
29
Blatska blatina
2
2,010
14.6
8.23
78.4
25.1
380
3.2
285
754
46.9
39
Kozarica intake structure
1
5,620
15.2
7.24
126.4
90.8
728
3.4
510
1,436
50.1
32
Slatina
0.5
6,550
14.7
7.26
127.6
90.6
891
3.4
510
1,781
42.5
22
Prožurska blatina
0.5
17,170
19.6
8.5
171.2
338.9
2,520
52
580
4,889
430
0
Vodice spring
103
762
14.4
7.55
80.8
35.2
24
1.2
290
47.6
11.2
0
MIN 2016
Spilja intake structure—Sobra
4
3,300
—
8.2
140
61
410
15
280
790
100
<10
Drinking water
2,500
25
6.6-9.5
n/a
n/a
200
12
n/a
250
250
50
Sources: data for 2005 and 2006 [10]; standards for drinking water [38]. Abbreviations: MIN: hydrological minimum; MAX: hydrological maximum; both with respect to groundwater levels.
