International Journal of Marine Science, 2017, Vol.7, No.13, 114-124
117
The geo-accumulation index (I
geo
) used to estimate the pollution condition of metals in sediments based on
comparing current state with the preindustrial levels. This index was defined by Muller (1979) as the following
equation:
= [ /( .
)]
Where C
n
is the measured metal concentration, and B
n
is the background level. The pollution extent could be
classified according to the scale proposed by Muller (1981) who distinguished seven classes of contamination
(Table 1).
Table 1 Classification of geo-accumulation index (I
geo
) (Muller, 1981)
I
geo
value
Class
Sediments quality
<0
0
Unpolluted
0–1
1
Unpolluted to moderately polluted
1–2
2
Moderately polluted
2–3
3
Moderately to strongly polluted
3–4
4
Strongly polluted
4–5
5
Strongly to very strongly polluted
>5
6
Very strongly polluted
2 Results and Discussions
2.1 Total concentrations of heavy metals
Mean concentrations of heavy metals in the surface sediments are shown in Table 2. Overall collected samples,
the mean of metal concentrations ranged from 11.2 to 145.3, 14.2-225.5, 18.5-90.8, 1.4-5.6, 1373-31089,
72.5-758.5, 15.3-65.7 and 10.2-26.3 µg/g for Cu, Zn, Pb, Cd, Fe, Mn, Ni and Co, respectively. Regarding the
order of metal abundance, average concentrations of metals were found in following order: Cd (3.5) < Co (15.6) <
Ni (32.0) < Cu (41.3) < Pb (46.7) < Zn (58.4) << Mn (277.4) <<< Fe (10,603 µg/g).
Table 2 Mean of heavy metals concentrations (µg/g) in surface sediments from different locations
Location
Cu
Zn
Pb
Cd
Fe
Mn
Ni
Co
G1
25.0±7.2
34.3±17.7
32.7±5.4
3.2±0.6
5289±820
148.3±81.3
24.0±4.4
13.7±1.2
G2
22.1±2.7
31.1±11.0
39.4±8.8
3.4±0.8
4128±868
129.8±92.8
22.1±2.6
13.6±1.4
G3
25.1±10.4
24.9±11.2
46.0±4.7
4.0±0.6
3324±1309
135.3±64.2
18.3±2.1
13.8±1.7
H1
38.6±19.3
47.5±15.4
45.5±8.7
3.6±0.5
8258±2716
250.3±88.1
28.4±6.1
14.8±1.4
H2
106.8±30.5
174.2±36.1
76.1±11.4
4.4±0.9
10984±2112
214.3±20.8
38.4±14.5
14.3±3.0
H3
45.4±27.7
39.9±17.0
49.5±11.2
3.1±0.5
6861±317
161.9±61.0
22.2±3.9
14.3±3.2
S1
74.5±34.4
73.3±23.6
56.4±13.8
3.5±0.4
17998±5490
378.5±187.8
38.4±17.8
19.1±5.4
S2
34.3±9.8
70.2±20.8
46.7±11.8
4.3±0.5
16436±2120
470.0±89.3
34.6±7.1
14.0±2.0
S3
28.8±14.5
46.6±19.5
30.9±13.0
2.7±0.3
19296±8007
536.7±203.0
35.1±6.0
19.2±4.7
Q1
24.9±13.8
32.4±23.1
49.1±10.5
1.9±0.5
5258±1885
185.2±48.2
27.9±9.8
14.5±3.5
Q2
43.5±9.9
88.2±19.4
54.8±16.0
5.1±0.5
17676±1052
431.0±123.1
58.9±7.4
20.4±2.5
Q3
26.1±8.3
37.9±6.8
33.7±12.1
2.9±1.1
11731±1960
288.1±44.0
35.7±7.3
15.2±5.7
Average
41.3
58.4
46.7
3.5
10603
277.4
32.0
15.6
Max.
106.8
174.2
76.1
5.1
19296
536.7
58.9
20.4
Min.
22.1
24.9
30.9
1.9
3324
129.8
18.3
13.6
Variations in metal concentrations along studied locations were considerable. Table 3 shows ANOVA results for
significant differences between locations. As shown in Figure 2, Cu recoded highest concentrations in H2
(106.8±30.5 µg/g) followed by S1 (74.5±34.4 µg /g) which corresponded to the stations of Hurghada Port area
and Safaga Marina, respectively. Other stations were significantly lower than those values. Similarly, significant
high levels of Zn were recorded in Hurghada port (H2), (174.2±36.1 µg/g), which is high with about two times the
concentrations in other locations. Apparently, this high sedimentary Zn and Cu in the port (and partially in marina)
is attributed to the antifouling paints from the boats and the nearby shipyard. Copper and zinc-based antifouling
