Due to the absence of specific regulatory information for the AG region (Al-Taani et al., 2014; Badr et al., 2009; Batley et al., 2013; Cameron, 1992; CCREM, 1987; De Mora et al., 2004; El-Sorogy et al., 2016; FDEP, 1995; Manju et al., 2008; Mahboob et al., 2021; Mansour et al., 2011; U.S. Environmental Protection Agency, 2024; U.S. Hazardous Site Control Division et al., 1996), a comparison with the EPA Sediment Quality Guidelines (SQGs) was conducted to assess the compliance of HM concentrations in the provided data with general regulatory limits (Batley et al., 2013; CCREM, 1987; FDEP, 1995; U.S. Environmental Protection Agency, 2024; U.S. Hazardous Site Control Division et al., 1996). These guidelines are used to evaluate the potential ecological risk associated with sediment quality (i.e., the potential adverse effects on aquatic organisms) and include the Threshold Effect Concentration (TEC), levels below which no harmful effects are expected in the environment, and the Probable Effect Concentration (PEC) (Batley et al., 2013; Manju et al., 2008; U.S. Environmental Protection Agency, 2024), levels above which harmful effects are likely to occur. Here, the TEC represents a concentration of an element or substance above which harmful effects on organisms are likely to occur, whereas the PEC is the estimated concentration of a substance at which harmful effects on organisms are expected to occur. The PEC is useful in scenarios where the likelihood of adverse effects is assessed to make predictions based on environmental concentrations of contaminants and to consider factors such as exposure pathways, transport, and bioavailability. Hence, the sediment sample results of this study are evaluated using the PEC values as a standard for comparison.
Table 2
Heavy metals concentration in sediment samples collected from different locations of the Arabian Gulf.
Sample Name
|
Heavy metals (mg/kg)
|
Cr
|
Mn
|
Fe
|
Co
|
Ni
|
Cu
|
(G1)
|
37.5\(\pm 0.8\)
|
33.9\(\pm 2.6\)
|
1440\(\pm 1.5\)
|
26.5\(\pm 26.5\)
|
10.3\(\pm 1.4\)
|
3.61\(\pm 1.2\)
|
(G2)
|
13.6\(\pm 2.1\)
|
16.8\(\pm 1.8\)
|
1310\(\pm 2.1\)
|
25.3\(\pm 1.2\)
|
9.7\(\pm 3.2\)
|
3.6\(\pm 1.2\)
|
(G3)
|
48\(\pm 0.4\)
|
152\(\pm 2.8\)
|
4120\(\pm 3.0\)
|
7.5\(\pm 1.4\)
|
43.1\(\pm 1.0\)
|
17.3\(\pm 1.7\)
|
(G4)
|
8.76\(\pm\) 3.1
|
28.4\(\pm 3.2\)
|
934\(\pm 1.8\)
|
13.4\(\pm 1.4\)
|
10.2\(\pm 2.3\)
|
4.51\(\pm 2.2\)
|
(PO)
|
44.5\(\pm 2.7\)
|
170\(\pm 2.6\)
|
6980\(\pm 2.3\)
|
54.3\(\pm 1.2\)
|
30.4\(\pm 0.6\)
|
9.47\(\pm 3.1\)
|
(P9)
|
90.7\(\pm 1.4\)
|
212\(\pm 1.9\)
|
10200\(\pm 2.3\)
|
26.9\(\pm 3.1\)
|
50.6\(\pm 2.8\)
|
15.1\(\pm 1.2\)
|
(P10)
|
44.2\(\pm 2.8\)
|
142\(\pm 3.1\)
|
5250\(\pm 2.8\)
|
13.6\(\pm 1.5\)
|
22.6\(\pm 0.5\)
|
6.04\(\pm 3.1\)
|
(P11)
|
164\(\pm 1.6\)
|
433\(\pm 2.2\)
|
17400\(\pm 1.5\)
|
31.3\(\pm 2.3\)
|
78.9\(\pm 1.3\)
|
21.3\(\pm 3.2\)
|
(P12)
|
160\(\pm 0.87\)
|
382\(\pm 1.37\)
|
14800\(\pm 1.31\)
|
22\(\pm 2.10\)
|
58.5\(\pm 1.86\)
|
15\(\pm 2.69\)
|
(P13)
|
194\(\pm 1.8\)
|
391\(\pm 2.1\)
|
14000\(\pm 3.1\)
|
27\(\pm 1.2\)
|
58.2\(\pm 0.9\)
|
14.8\(\pm 0.9\)
|
(P14)
|
232\(\pm 1.4\)
|
452\(\pm 1.8\)
|
20900\(\pm 2.2\)
|
27.1\(\pm 3.2\)
|
105\(\pm 1.8\)
|
19.8\(\pm 2.0\)
|
(P15)
|
176\(\pm 1.1\)
|
328\(\pm 0.6\)
|
11100\(\pm 0.7\)
|
29.6\(\pm 1.5\)
|
55.3\(\pm 1.2\)
|
12.1\(\pm 3.1\)
|
(P16)
|
-
|
298\(\pm 1.6\)
|
-
|
18.3\(\pm 3.4\)
|
96\(\pm 1.7\)
|
13.3\(\pm 1.2\)
|
(P17)
|
196\(\pm 1.9\)
|
340\(\pm 3.3\)
|
12200\(\pm 3.1\)
|
22.8\(\pm 3.2\)
|
80.2\(\pm 2.1\)
|
13.9\(\pm 2.6\)
|
(P18)
|
109\(\pm 2.1\)
|
273\(\pm 2.0\)
|
10100\(\pm 3.0\)
|
19.8\(\pm 1.6\)
|
51.7\(\pm 2.7\)
|
13.4\(\pm 3.1\)
|
(P19)
|
104\(\pm 1.0\)
|
279\(\pm 1.2\)
|
9180\(\pm 1.0\)
|
14\(\pm 2.1\)
|
60.4\(\pm 2.1\)
|
17.2\(\pm 1.1\)
|
(P20)
|
27.9\(\pm 1.7\)
|
24.1\(\pm 1.7\)
|
888\(\pm 2.2\)
|
7.31\(\pm 1.7\)
|
8.72\(\pm 1.6\)
|
1.64\(\pm 2.3\)
|
(P21)
|
18.4\(\pm 3.3\)
|
24.1\(\pm 1.7\)
|
774\(\pm 0.7\)
|
16.5\(\pm 2.2\)
|
11.3\(\pm 2.2\)
|
14.2\(\pm 2.2\)
|
(P22)
|
17.4\(\pm 0.9\)
|
24.5\(\pm 0.9\)
|
728\(\pm 1.0\)
|
12.1\(\pm 1.4\)
|
10.2\(\pm 1.1\)
|
17.8\(\pm 1.2\)
|
(P24)
|
26.9\(\pm 0.3\)
|
15.9\(\pm 3.0\)
|
567\(\pm 2.9\)
|
13.5\(\pm 2.4\)
|
11.9\(\pm 2.7\)
|
19.2\(\pm 0.7\)
|
(P25)
|
69.1\(\pm 2.4\)
|
58.7\(\pm 1.5\)
|
1370\(\pm 1.2\)
|
11.5\(\pm 1.5\)
|
12.6\(\pm 1.1\)
|
18.7\(\pm 1.8\)
|
(P26)
|
90.1\(\pm 2.6\)
|
69.2\(\pm 3.1\)
|
1920\(\pm 3.1\)
|
9.9\(\pm 3.2\)
|
19.9\(\pm 2.5\)
|
31.9\(\pm 2.6\)
|
(P27)
|
193\(\pm 2.8\)
|
123\(\pm 0.8\)
|
2510\(\pm 2.1\)
|
6.01\(\pm 3.1\)
|
16.5\(\pm 2.4\)
|
25.3\(\pm 3.0\)
|
(P28)
|
19.9\(\pm 1.5\)
|
9.33\(\pm 3.1\)
|
355\(\pm 3.4\)
|
17.9\(\pm 2.3\)
|
11.5\(\pm 2.0\)
|
18\(\pm 1.7\)
|
(P29)
|
217\(\pm 3.1\)
|
160\(\pm 2.8\)
|
3410\(\pm 2.6\)
|
8.6\(\pm 2.5\)
|
35\(\pm 2.6\)
|
137\(\pm 1.9\)
|
(P30)
|
45.7\(\pm 2.6\)
|
56.6\(\pm 1.0\)
|
2220\(\pm 0.4\)
|
5.09\(\pm 2.1\)
|
19.8\(\pm 2.6\)
|
69.3\(\pm 1.4\)
|
(P31)
|
52.6\(\pm 2.4\)
|
38.4\(\pm 2.3\)
|
1550\(\pm 1.9\)
|
8.22\(\pm 3.2\)
|
19.1\(\pm 1.7\)
|
63.9\(\pm 0.8\)
|
(P32)
|
45.3\(\pm 2.3\)
|
58.7\(\pm 0.9\)
|
2170\(\pm 1.9\)
|
3.25\(\pm 2.3\)
|
13.1\(\pm 1.9\)
|
45.1\(\pm 1.4\)
|
(P33)
|
31.9\(\pm 1.0\)
|
29\(\pm 2.9\)
|
1530\(\pm 2.0\)
|
5.68\(\pm 2.3\)
|
10.4\(\pm 1.7\)
|
37.8\(\pm 0.6\)
|
(P34)
|
88.3\(\pm 3.2\)
|
70.4\(\pm 2.2\)
|
2520\(\pm 3.3\)
|
8.18\(\pm 2.5\)
|
14.1\(\pm 1.8\)
|
39.3\(\pm 2.4\)
|
(P35)
|
29.2\(\pm 0.4\)
|
16\(\pm 0.5\)
|
972\(\pm 1.2\)
|
4.4\(\pm 1.8\)
|
12.5\(\pm 0.6\)
|
34.7\(\pm 0.1\)
|
(P37)
|
34.3\(\pm 2.1\)
|
36.4\(\pm 0.4\)
|
1820\(\pm 1.2\)
|
3.24\(\pm 1.8\)
|
14.2\(\pm 3.3\)
|
75.8\(\pm 0.4\)
|
Table 3
Heavy metals concentration in sediment samples collected from different locations of the Arabian Gulf (Cont.)
Sample Name
|
Heavy metals (mg/kg)
|
Zn
|
As
|
Se
|
Sr
|
Mo
|
Ag
|
(G1)
|
6.9\(\pm 2.1\)
|
24\(\pm 3.1\)
|
< LLD
|
1720\(\pm 2.1\)
|
0.16\(\pm 3.2\)
|
0.86\(\pm 1.5\)
|
(G2)
|
6.6\(\pm 2.4\)
|
15.3\(\pm 2.6\)
|
< LLD
|
2540\(\pm 1.6\)
|
0.20\(\pm 1.2\)
|
1.1\(\pm 2.3\)
|
(G3)
|
28.5\(\pm 1.6\)
|
40.2\(\pm 0.3\)
|
< LLD
|
1430\(\pm 2.2\)
|
0.42\(\pm 2.5\)
|
0.43\(\pm 1.8\)
|
(G4)
|
5.39\(\pm 1.7\)
|
21.2\(\pm 1.4\)
|
< LLD
|
3540\(\pm 2.2\)
|
0.14\(\pm 2.1\)
|
1.3\(\pm 3.1\)
|
(PO)
|
21\(\pm 0.4\)
|
46.2\(\pm 1.0\)
|
< LLD
|
3020\(\pm 2.2\)
|
0.38\(\pm 2.5\)
|
1.99\(\pm 1.1\)
|
(P9)
|
83\(\pm 0.4\)
|
57.7\(\pm 0.4\)
|
< LLD
|
3460\(\pm 0.4\)
|
1.01\(\pm 3.1\)
|
1.71\(\pm 1.7\)
|
(P10)
|
14.4\(\pm 2.0\)
|
31.6\(\pm 2.6\)
|
< LLD
|
1160\(\pm 1.9\)
|
0.20\(\pm 1.1\)
|
0.48\(\pm 1.3\)
|
(P11)
|
49.4\(\pm 0.7\)
|
65.3\(\pm 1.9\)
|
< LLD
|
1410\(\pm 1.1\)
|
0.59\(\pm 2.1\)
|
1.00\(\pm 3.1\)
|
(P12)
|
37.6\(\pm 1.93\)
|
63.4\(\pm 1.26\)
|
< LLD
|
1430\(\pm 0.48\)
|
0.54\(\pm 1.40\)
|
0.68\(\pm 1.60\)
|
(P13)
|
38.9\(\pm 1.7\)
|
57\(\pm 0.6\)
|
< LLD
|
1670\(\pm 1.2\)
|
0.51\(\pm 3.2\)
|
0.86\(\pm 3.1\)
|
(P14)
|
53.8\(\pm 2.2\)
|
21.75\(\pm 2.8\)
|
< LLD
|
1320\(\pm 1.1\)
|
0.71\(\pm 1.4\)
|
0.84\(\pm 1.6\)
|
(P15)
|
28.9\(\pm 1.6\)
|
25.3\(\pm 0.8\)
|
< LLD
|
1580\(\pm 1.7\)
|
0.42\(\pm 3.2\)
|
0.88\(\pm 0.7\)
|
(P16)
|
29\(\pm 1.7\)
|
31.6\(\pm 2.4\)
|
< LLD
|
1730\(\pm 1.8\)
|
0.90\(\pm 2.4\)
|
0.73\(\pm 1.8\)
|
(P17)
|
31.5\(\pm 2.8\)
|
5.2\(\pm 1.7\)
|
< LLD
|
1760\(\pm 3.0\)
|
0.63\(\pm 1.9\)
|
0.93\(\pm 2.2\)
|
(P18)
|
26.6\(\pm 2.1\)
|
8.3\(\pm 0.6\)
|
< LLD
|
1910\(\pm 1.1\)
|
0.32\(\pm 2.0\)
|
0.86\(\pm 2.2\)
|
(P19)
|
34.5\(\pm 2.1\)
|
41.6\(\pm 1.6\)
|
< LLD
|
1360\(\pm 1.2\)
|
0.40\(\pm 1.4\)
|
0.53\(\pm 2.2\)
|
(P20)
|
5.55\(\pm 1.9\)
|
8.7\(\pm 2.2\)
|
< LLD
|
2550\(\pm 1.1\)
|
0.41\(\pm 1.6\)
|
0.8\(\pm 1.8\)
|
(P21)
|
3.3\(\pm 11.3\)
|
9.2\(\pm 2.1\)
|
< LLD
|
2450\(\pm 2.4\)
|
0.21\(\pm 1.7\)
|
0.98\(\pm 1.4\)
|
(P22)
|
4.68\(\pm 2.3\)
|
23.7\(\pm 1.9\)
|
< LLD
|
2580\(\pm 2.4\)
|
0.13\(\pm 2.8\)
|
1.14\(\pm 3.1\)
|
(P24)
|
2.04\(\pm 1.1\)
|
16.8\(\pm 3.1\)
|
< LLD
|
2690\(\pm 2.3\)
|
0.17\(\pm 1.1\)
|
1.12\(\pm 2.4\)
|
(P25)
|
4.66\(\pm 2.3\)
|
40.6\(\pm 0.8\)
|
< LLD
|
2710\(\pm 3.1\)
|
0.20\(\pm 2.7\)
|
1.1\(\pm 2.4\)
|
(P26)
|
8.08\(\pm 0.5\)
|
17.7\(\pm 1.6\)
|
< LLD
|
2410\(\pm 0.7\)
|
0.31\(\pm 2.5\)
|
0.83\(\pm 1.8\)
|
(P27)
|
8.55\(\pm 2.0\)
|
2.9\(\pm 2.1\)
|
< LLD
|
1920\(\pm 0.7\)
|
0.24\(\pm 4.5\)
|
0.93\(\pm 3.1\)
|
(P28)
|
1.44\(\pm 1.4\)
|
21.7\(\pm 2.1\)
|
< LLD
|
3720\(\pm 0.9\)
|
0.16\(\pm 2.7\)
|
1.88\(\pm 1.9\)
|
(P29)
|
39.5\(\pm 3.1\)
|
13\(\pm 1.6\)
|
< LLD
|
1370\(\pm 1.5\)
|
0.65\(\pm 2.7\)
|
0.75\(\pm 2.8\)
|
(P30)
|
7.01\(\pm 2.2\)
|
13.4\(\pm 3.0\)
|
< LLD
|
642\(\pm 0.1\)
|
0.26\(\pm 3.1\)
|
0.41\(\pm 2.8\)
|
(P31)
|
8.2\(\pm 2.4\)
|
9.1\(\pm 2.3\)
|
<LLD
|
843\(\pm 1.2\)
|
0.34\(\pm 1.2\)
|
0.35\(\pm 2.3\)
|
(P32)
|
8.51\(\pm 3.2\)
|
10.6\(\pm 1.2\)
|
< LLD
|
272\(\pm 0.6\)
|
0.21\(\pm 2.4\)
|
0.32\(\pm 3.2\)
|
(P33)
|
6.17\(\pm 3.1\)
|
10.2\(\pm 3.0\)
|
< LLD
|
561\(\pm 0.7\)
|
0.23\(\pm 2.4\)
|
0.33\(\pm 1.9\)
|
(P34)
|
5.83\(\pm 2.4\)
|
18.2\(\pm 1.9\)
|
< LLD
|
1230\(\pm 0.7\)
|
0.32\(\pm 2.7\)
|
0.53\(\pm 2.3\)
|
(P35)
|
6.08\(\pm 2.1\)
|
10.8\(\pm 1.2\)
|
< LLD
|
666\(\pm 0.7\)
|
0.42\(\pm 3.1\)
|
0.32\(\pm 2.4\)
|
(P37)
|
24\(\pm 2.0\)
|
9.6\(\pm 1.3\)
|
< LLD
|
291\(\pm 1.5\)
|
0.51\(\pm 2.1\)
|
0.23\(\pm 3.2\)
|
Table 4
Heavy metals concentration in sediment samples collected from different locations of the Arabian Gulf (Cont.)
Sample Name
|
Heavy metals (mg/kg)
|
Cd
|
Pb
|
Hf
|
Sn
|
Ti
|
(G1)
|
1.34\(\pm 2.2\)
|
1.8\(\pm 3.0\)
|
< LLD
|
0.16\(\pm 2.2\)
|
154\(\pm 2.9\)
|
(G2)
|
< LLD
|
1.5\(\pm 0.9\)
|
< LLD
|
0.3\(\pm 2.5\)
|
78.9\(\pm 2.5\)
|
(G3)
|
2.42\(\pm 1.4\)
|
3.88\(\pm 2.4\)
|
< LLD
|
0.79\(\pm 2.2\)
|
474\(\pm 2.2\)
|
(G4)
|
< LLD
|
2.12\(\pm 2.3\)
|
< LLD
|
0.16\(\pm 1.7\)
|
68.1\(\pm 3.1\)
|
(PO)
|
0.05\(\pm 1.6\)
|
4.43\(\pm 1.4\)
|
0.06\(\pm 1.9\)
|
0.31\(\pm 2.4\)
|
247\(\pm 1.7\)
|
(P9)
|
< LLD
|
4.36\(\pm 1.1\)
|
0.31\(\pm 1.8\)
|
0.83\(\pm 1.1\)
|
545\(\pm 1.7\)
|
(P10)
|
< LLD
|
3.45\(\pm 0.7\)
|
0.162\(\pm 1.5\)
|
0.23\(\pm 1.6\)
|
325\(\pm 3.1\)
|
(P11)
|
0.15\(\pm 2.2\)
|
6.32\(\pm 0.8\)
|
0.46\(\pm 1.2\)
|
0.85\(\pm 2.1\)
|
1200\(\pm 3.3\)
|
(P12)
|
< LLD
|
5.53\(\pm 1.05\)
|
0.67\(\pm 3.27\)
|
0.69\(\pm 1.57\)
|
1040\(\pm 1.83\)
|
(P13)
|
< LLD
|
5.97\(\pm 1.6\)
|
0.61\(\pm 1.8\)
|
0.65\(\pm 3.3\)
|
889\(\pm 2.8\)
|
(P14)
|
0.09\(\pm 1.2\)
|
8.08\(\pm 2.3\)
|
1.06\(\pm 2.5\)
|
0.98\(\pm 2.1\)
|
1260\(\pm 2.8\)
|
(P15)
|
< LLD
|
5.73\(\pm 0.6\)
|
0.5\(\pm 1.4\)
|
0.51\(\pm 1.7\)
|
785\(\pm 3.1\)
|
(P16)
|
< LLD
|
3.72\(\pm 1.2\)
|
0.4\(\pm 3.1\)
|
0.59\(\pm 3.2\)
|
779\(\pm 1.7\)
|
(P17)
|
0.03\(\pm 1.1\)
|
4.22\(\pm 1.8\)
|
0.53\(\pm 2.4\)
|
0.59\(\pm 3.1\)
|
830\(\pm 1.1\)
|
(P18)
|
< LLD
|
4.09\(\pm 1.1\)
|
0.31\(\pm 1.6\)
|
0.44\(\pm 3.6\)
|
663\(\pm 1.9\)
|
(P19)
|
0.12\(\pm 1.6\)
|
5.0\(\pm 1.4\)
|
0.16\(\pm 2.4\)
|
0.61\(\pm 0.4\)
|
782\(\pm 1.9\)
|
(P20)
|
< LLD
|
2.1\(\pm 1.2\)
|
0.09\(\pm 1.4\)
|
0.17\(\pm 2.4\)
|
172\(\pm 1.6\)
|
(P21)
|
< LLD
|
2.25\(\pm 2.0\)
|
0.08\(\pm 2.3\)
|
0.47\(\pm 0.8\)
|
139\(\pm 1.4\)
|
(P22)
|
< LLD
|
2.11\(\pm 1.6\)
|
0.09\(\pm 1.8\)
|
0.59\(\pm 1.2\)
|
124\(\pm 1.0\)
|
(P24)
|
< LLD
|
1.01\(\pm 0.8\)
|
< LLD
|
0.53\(\pm 3.5\)
|
94.8\(\pm 2.3\)
|
(P25)
|
< LLD
|
2.24\(\pm 0.6\)
|
0.13\(\pm 2.6\)
|
0.65\(\pm 3.1\)
|
257\(\pm 2.2\)
|
(P26)
|
< LLD
|
23.9\(\pm 0.5\)
|
0.18\(\pm 2.1\)
|
1.01\(\pm 0.6\)
|
351\(\pm 2.8\)
|
(P27)
|
< LLD
|
2.82\(\pm 1.0\)
|
0.28\(\pm 2.2\)
|
0.91\(\pm 0.5\)
|
565\(\pm 3.0\)
|
(P28)
|
< LLD
|
2.79\(\pm 0.6\)
|
< LLD
|
0.49\(\pm 2.7\)
|
69\(\pm 2.5\)
|
(P29)
|
< LLD
|
6.26\(\pm 0.5\)
|
0.82\(\pm 2.3\)
|
3.9\(\pm 1.5\)
|
679\(\pm 3.1\)
|
(P30)
|
< LLD
|
5.88\(\pm 1.2\)
|
0.57\(\pm 2.7\)
|
1.91\(\pm 0.5\)
|
302\(\pm 1.2\)
|
(P31)
|
<LLD
|
4.52\(\pm 1.2\)
|
0.09\(\pm 1.1\)
|
1.87\(\pm 0.7\)
|
234\(\pm 3.2\)
|
(P32)
|
< LLD
|
3.45\(\pm 1.8\)
|
0.92\(\pm 1.4\)
|
1.38\(\pm 2.4\)
|
404\(\pm 1.4\)
|
(P33)
|
< LLD
|
3.32\(\pm 0.7\)
|
0.67\(\pm 1.6\)
|
1.15\(\pm 2.3\)
|
233\(\pm 2.8\)
|
(P34)
|
< LLD
|
3.49\(\pm 1.5\)
|
0.26\(\pm 3.0\)
|
1.28\(\pm 1.5\)
|
365\(\pm 4.8\)
|
(P35)
|
< LLD
|
3.6\(\pm 1.7\)
|
0.26\(\pm 2.8\)
|
1.13\(\pm 1.1\)
|
176\(\pm 3.1\)
|
(P37)
|
< LLD
|
13\(\pm 0.9\)
|
0.5\(\pm 2.4\)
|
1.61\(\pm 3.2\)
|
276\(\pm 3.1\)
|
A thorough examination of the HM concentrations in the sediment samples, as outlined in Tables 2, 3, and 4, and subsequent comparison with the PEC SQGs (Batley et al., 2013; Manju et al., 2008; U.S. Environmental Protection Agency, 2024) provided by the EPA revealed several instances of elevated levels surpassing established standards. It is essential to note that such evaluations are crucial in understanding the potential environmental impact and formulating effective management strategies.
Starting with Chromium (Cr) and Manganese (Mn), the concentrations in the analysed samples generally fall within acceptable limits, not surpassing the PEC levels set by the EPA (2100 mg/kg for Cr and 3200 mg/kg for Mn). This result indicates a relatively no risk associated with these particular metals. Conversely, the situation differs significantly for Iron (Fe), where the levels notably exceed the recommended PEC value of 10,000 mg/kg. Sample P14, in particular, exhibits the Fe concentration of 20,900 mg/kg, underscoring the need for further investigation in this specific location. This point is located in the open sea northern AG, as shown in Fig. 3.
Cobalt (Co) in some samples exceeded the PEC value of 29 mg/kg. Sample PO, just north of Jinna island, stands out with a Co concentration of 54.3 mg/kg, Nickel (Ni) and Copper (Cu) concentrations, with recommended PEC values of 280 mg/kg and 140 mg/kg, respectively, generally remain within acceptable limits across all samples.
Zinc (Zn) concentrations do not breach the PEC threshold of 2700 mg/kg, suggesting no risk associated with this metal in the analysed samples. In contrast, Arsenic (As) in some samples exhibiting levels surpassing the recommended PEC value of 22 mg/kg. Notably, sample G3 showcases high As concentration of 40.2 mg/kg. Other samples, including P9 (57.7 mg/kg), P11 (65.3 mg/kg), P12 (63.4 mg/kg), and P13 (57 mg/kg), also exceed the recommended levels.
Silver (Ag) levels are elevated in some sediment samples, surpassing the recommended PEC value of 0.79 mg/kg. Sample PO stands out with a silver concentration of 1.99 mg/kg. The situation is nuanced for Cadmium (Cd), with sample G3 slightly exceeding the recommended PEC value of 2.1 mg/kg at 2.42 mg/kg, while most other samples remain below the detection limit. Selenium (Se) is consistently below the detection limit; hence, a conclusive evaluation cannot be conducted.
Encouragingly, the Lead (Pb) and Tin (Sn) levels do not breach the recommended PEC values of 84 mg/kg and 30 mg/kg, respectively, across the analysed samples.
It is essential to highlight that Strontium (Sr), Molybdenum (Mo), Hafnium (Hf), and Titanium (Ti) lack specified PEC values in the EPA SQG guidelines. As such, a comprehensive comparative analysis of these metals within the given context remains elusive.
Figure 3 shows the sediment samples' average Fe, Sr, Ti, and Mn concentrations. In particular, the average Fe concentration reaches more than 5000 mg/kg. However, the average Mn concentration does not give rise to concern or exceed the PEC levels. No conclusions can be drawn for the average Sr and Ti concentrations due to a lack of PEC data guidelines.
Figure 4 shows the average Cr, Co, Ni, Cu, Zn, and As concentrations across all sediment samples. The average As concentration reaches ~ 22 mg/kg, which is comparable to an AG study near Dammam, Saudi Arabia (Mahboob et al., 2021). The average Cr, Co, Ni, Cu, and Zn concentrations do not give rise to concern or exceed the recommended PEC levels, as discussed above.
Figure 5 shows the average concentration of Mo, Ag, Cd, Pb, Hf, and Sn across all sediment samples. Notably, the average Ag and Cd concentrations are slightly higher than the recommended PEC value. Pb concentration levels do not breach the recommended PEC value.