Distribution of trace elements in nearshore surface sediments from the Jordan Gulf of Aqaba (Red Sea)

Distribution of trace elements in nearshore surface sediments from the Jordan Gulf of Aqaba (Red Sea)

M a r i n e Pollution Bulletin Marine Pollution Bulletin, Volume 18, No. 4, pp. 19t1-193, 1987. 0025-326X/87 $3.00+0.00 C 1987 PergamonJournals Ltd...

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M a r i n e Pollution Bulletin

Marine Pollution Bulletin, Volume 18, No. 4, pp. 19t1-193, 1987.

0025-326X/87 $3.00+0.00 C 1987 PergamonJournals Ltd.

Printed in Great Britain.

Distribution of Trace Elements

in Nearshore Surface

Sediments from t h e J o r d a n G u l f of Aqaba (Red Sea)

The town of Aqaba occupies the northernmost tip of the northeastern coast of the Gulf of Aqaba. The rapid industrial and social development, port expansion, and the high population growth rate of Aqaba and Eilat seem to contribute a significant amount of pollutants to the coastal environment and to exert some ecological impact on marine life in this environment (Fishelson, 1973; Loya, 1975; Walker & Ormond, 1982). A field survey was conducted in 1985 to measure the total and acid leachable (non-residual) concentrations and distributions of selected trace elements in coastal sediments from the northern portion of the Gulf of Aqaba (Fig. 1). Samples were collected by hand corers (perspex tubes 5 cm i.d. x 50 cm length) along a transect at each station at water depths of 5, 10, 20 and 30 m. Upon collection, each core was subdivided and the top 2 cm used for analysis, after being freed from coarse shell fragments, visible organisms, and seagrass leaves and roots when present. Samples were stored in labelled polyethylene bagsat_18oC. Before analysis the samples were thawed, oven-dried at 100°C for 36 h, ground and homogenized using a Retsch, Type RMO grinding mill equipped with a corundum pestle and mortar. The fine powder was stored in labelled plastic or glass containers until further analysis, Two types of metal analyses were performed: 1. total extract: complete dissolution of the sample by the use of concentrated HNO3, HCIO 4 and HF acids to give total

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element concentrations (Agemain & Chau, 1976, 1977). 2. dilute acid extraction (Malo, 1977): using 0.5 M HC1 instead of the 0.3 acid used in the original procedure. Analytical blanks and sediment samples were analysed in duplicate using the same procedures and reagents. Analyses were carried out by direct aspiration into an air-acetylene flame of Perkin-Elmer atomic absorption spectrophotometer Model 3030 equipped with a premix burner and a simultaneous background corrector. All glassware and sample containers were precleaned with detergent followed by soaking in a 10% HNO3 solution for at least 24 h, then rinsed 3 times with deionized distilled water. Analytical blanks were Cd, 0.00; Co, 0.00; Cr, 0.01; Cu, 0.01 ; Fe, 0.07; Mn, 0.02; Ni, 0.02; Pb, 0.00; and Zn, 0.01 gg 1-1. Organic matter was estimated as organic carbon by the acid dichromate digestion and titration method of Walkley & Black (1934) as modified by Gaudette et al. (1974). Carbonate content was determined by treating the sediment with a known volume of 1 M HC1 and back titrating the excess acid with 0.5 M NaOH (Anwar & Mohammed, 1970). It is obvious from the data in Table 1 that in the terrigenous sediments of Stn 1, 5, and 6 all trace elements except Fe and Mn tend to increase with increasing distance (and depth) from the coast, showing a general distribution pattern parallel to that of total organic carbon in these sediments. The coralline sediments of Stn 2 have the highest concentrations of Co and Pb, high concentrations of Cd and Ni, but low Cr, Cu, Fe, Mn, and Zn compared to the terrigenous sediments of Stn 1, 4, 5, and 6. The high percentages of the acid leachable fractions of Zn (48%), Cu (55%), Co (79%), and Ni (96%) indicate that substantial portions of these elements occur in fractions of the coralline sediments which are leachable by the dilute acid treatment. It also indicates the presence of an important anthropogenic input for these elements in this station. Stn 3 sediments have abnormally high concentrations (3-9 times) of Cd, Co, Cu, Pb, Zn and organic carbon compared to all other terrigenous sediments from other stations. Table 1 shows a common distribution pattern for Cd, Co, Cr, Cu, Ni, Pb, Zn, and organic carbon which is quite different from those depicted in other stations in that they tend to decrease as a function of distance (and depth) from the coast in a W to SW direction, whereas Fe and Mn tend to show a reverse trend as they tend to increase in a seaward direction. The comparatively high and anomalous trace element concentrations in Stn3 (except Fe and Mn) reflect the effect of phosphate rock particles that reach the sea bottom during loading of ships with this mineral in the port area, since these sparingly soluble particles usually contain high levels of Zn (190-490 ppm), Cd (9 ppm), and Cu (19-48 ppm) (Jordan Phosphate Co., 1985). On the other hand the

Volume 18/Number 4/April 1987

TABLE 1 Concentrations of total (a) and acid leachable (b) trace elements (ppm, dry wt) in surface sediments from various localities. Depth Cd Station(m) (a) (b)

Co (a) (b)

Cr (a) (b)

Cu (a) (b)

Fe (b)

(a)

Mn (a) (b)

1

5 10 20 30

3.0 3.5 4.5 6.0

1.2 1.8 2.5 4.0

31 30 35 40

7.0 11 15 21

30 22 56 44

8.0 8.0 6.0 7.5 8.0 10 7.0 10

4.0 4.0 6.0 6.0

25000 13625 15500 11875

2

5 10

9.0 5.2 9.5 5.2

55 56

43 44

27 25

4.4 4.4

4.0 4.0

5000 4100

550 775

3

5 10 20 30

8.7 9.0 5.7 3.9

45 42 33 37

21 22 21 21

120 130 78 45

13000 13250 16000 15800

5350 6875 8250 8025

4

5 10 20 30

2.5 3.0 2.0 2.0

1.2 1.6 1.8 1.4

21 25 26 22

15 18 19 17

18 27 23 15

3.0 4.0 4.0 4.0

5

5 10 20 30

3.5 4.0 5.0 4.5

1.5 1.8 2.4 2.0

35 37 43 41

11 9 16 16

31 42 38 40

6.6 5.6 8.3 14.2

7.5 8.0 9.5 9.5

6

5 10 20 30

4.5 5.0 4.5 4.5

1.8 2.1 2.6 2.1

35 35 40 36

16 19 23 20

172 175 186 168

10.2 10.2 9.6 8.5

7.5 8.0 9.5 9.5

18 17 11 10

~

47 80 43 20

7.0 7.5 26 27 22 21

5.9 10 6.5 10 6.3 10 5.8 9.5

18 26 36 64

44 46 54 46

25 27 38 33

0.147 0.214 0.397 0.393

64 53

16 17

56 57

54 54

220 225

74 77

31 31

14 16

0.351 38.5-87.20 0.299

167 198 269 275

94 133 180 200

49 49 35 35

35 35 27 27

180 37 185 40 185 40 190 49

250 260 170 150

199 196 125 97

18625 17250 17500 14875

7675 226 9425 218 7600 210 7950 186

47 75 73 87

19 25 25 20

ll 17 18 14

90 100 113 85

18 24 29 24

34 43 39 34

16 23 22 21

0.167 4.83-10.15 0.235 0.292 0.148

5.0 4.0 5.0 6.0

18125 21000 30625 32500

9750 265 8200 335 10000 500 15975 520

99 26 84 30 90 37 151 35

10 10 16 17

83 88 113 103

17 17 31 30

33 41 58 58

22 19 26 35

0.100 6.26-12.98 0.129 0.180 0.165

6.0 6.0 7.0 7.0

28000 28375 26250 26875

12075 610 11950 655 13650 625 12650 615

173 185 244 215

16 19 23 18

108 29 115 34 130 43 120 33

56 63 68 64

34 36 46 38

0.200 5.24-20.50 0.239 0.282 0.251

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0.568 0.768 0.591 0.470

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90 108 135 195

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10 12 17 22

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Zn (a) (b)

28 40 52 67

residu,d [non-leachable ) 7total ....... idual tacid-leachable ] .J el . . . .

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152 147 192 152

17 19 13 11

10150 425 7875 300 10000 340 7050 270

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Stations Fig. 2 Concentration (overall mean) values (ppm, dry wt) of total (residual+acid leachable) trace elements and organic carbon in sediments from various localities.

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Fig. 3 Distribution of acid leachable (A) and total (B) trace elements and organic carbon in surface sedimentsfrom Sm 3 as a function of depth and distance from the shore.

high levels of other trace elements such as Fe, Mn, Ni, and Pb in the sediments of Stn 3 do not seem to have a strong relation to phosphate pollution as they usually occur in comparatively low concentrations in the exported phosphate rock particles (Fe, 1190; Mn, 77: Ni, 20; Pb, 3 ppm) (Jordan Phosphate Co., 1985). The high levels of these elements at Stn 3, their unique distribution patterns, the high percentages ( 4 9 - 7 4 % ) of the acid leachable fractions of the elements, the high organic content and the significant correlations between these trace elements and organic carbon (Table 2) are most probably the consequence of the untreated sewage effluent discharged from A q a b a sewage treatment plant, the outlet of which is about 250 m from the south end of the phosphate loading berth in the main port area (Fig. 1). Table 1 also shows clearly that Pb concentrations at Stns 1, 2, and 3 are significantly higher than those found in the southern section. In addition to the input from the municipal sewage the elevated levels of Pb in the three stations of the northern section can be attributed to the effect of ship and boat activities in this section. A distinct feature of this element compared to other elements is the narrow range and low percentages of the acid leachable fractions compared to the corresponding total Pb content in all sediments. The results (Table 1) indicate that the acid leachable (non-residual) Pb is only about onethird of the total element concentration in all sediments and all stations• At Stn 6 the highest element concentrations occur at 20 m rather than 30 m which is the depth of m a x i m u m concentrations at Stns 1 and 5. The high concentrations 192

TABLE 2 Associations of total (1) and acid-leachable (2) trace elements with organic carbon (%) and total iron as determined by linear correlation coefficients(n=21). Element

Organic Carbon

Fe (total)

Cd (1)

0.35 ns

Co (1) Co (2)

0.88* 0.92* o.4o ns o.66*

Cr (1) Cr (2)

0.30 ns o.64*

0.36 ns

Cu (I) Cu (2) Ve(1) Fe (2) Mn (1)

0.91" 0.91"

0.24 ns

Cd (2)

0.53 ns

0.53 ns

0.45 ns 0.36 ns 0.24 ns

0.84*

Mn (2)

Ni (1) Ni (2)

0.22 ns 0.92*

0.33 ns

Pb (1) Pb (2)

0.88* 0.64*

0.20 ns

Zn (1) 0.89* Zn (2) O.9O* (a)totalelement (2) acid-leachable fraction * significant at 0.01 level. ns not significant at 0.01 level.

0.72*

of trace elements in this station are mainly due to the direct effect of the discharge of 20 000 1 h -~ of warm cooling water from the Jordan Fertilizer Industries

Volume 18/Number 4/April 1987

Plant which is discharged into the sea from a main outlet at a depth of 23 m and a distance of 90 m from

Agemain, H. & Chau, A. S. Y. (I977). A study of different analytical

the shoreline.

Anwar, Y. M. & Mohamed, M. A. (1970). The distribution of calcium carbonate in continental shelf sediments of the Mediterranean Sea north of Nile Delta in the U.A.R. Bull. Inst. Oceanogr. Fish. 1 , 4 4 9 460. Fishelson, L. (1973). Ecology of coral reefs in the Gulf of Aqaba (Red Sea) influenced by pollution. Oecologia 12, 55-67. Gaudette, H. E., Flight, W. R., Toner, L. & Folder. D. W. (1974). An unexpensive titration method for the determination of organic carbon in recent sediments. Jour. Sed. Petrol. 44,249-253. Jordan Phosphate Mines Company Director (1985). (pets. comm.). Aqaba office. Aqaba, Jordan. Loya, Y. (1975). Possible effects of water pollution on the community structure of Red Sea corals. Mar. Biol. 29, 177-185. Mato, B. A. (1977). Partial extraction of metals from aquatic sediments. Environ. Sci. Technol. 11,277-288. Walker, D. I. & Ormond, R. F. G. (1982). Coral death from sewage and phosphate pollution at Aqaba, Red Sea. Mar. Pollut. Bull. 13, 21-25. Walkley, A. & Black, I. A. (1934). A n examination of the Degtjareff method for determining soil organic matter and a proposed modiflcation of the chromic acid titration method. Soil. Sci. 37, 29-38.

I would like to thank Dr. J. De Vaugelas for his assistance in obtaining thc sediment samples, Dr. M. Wahbeh and Mrs. R. Jafary who read the manuscript, and Mr. M. Badran for having performed the analyses of the samples. This work was supported by the Marine Science Station (University of Jordan-Yarmouk University).

A H M A D H. A B U - H I L A L Marine Science Station, Aqaba, Jordan Present address: Department of Earth and Environmental Sciences, Yarmouk University, Irbid, Jordan. Agemain, H. & Chau, A. S. Y. (1976). Evaluation of extraction techniques for the determination of metals in aquatic sediments. Analyst 101,761-767.

extractionmethods for nondetrital heavy metals in aquatic sediments.Arch. Environ. Contam. Toxicol. 6, 69-82.

MarinePollutionBulletin,Volume18, No. 4, pp. 193-194, 1987. Printedin GreatBritain.

Observations on Trace Metal C o n c e n t r a t i o n s in a

Carcharhinid Shark, Galeorhinus galeus, from Ii

n

i

" - " v e r y ° ° " v'

a

Trace metal levels in sharks from British waters have been reported by several workers in the past (Stevens & Brown, 1974; Davies, 1981 ; McKie & Topping, 1982). Liverpool Bay is an area which is known to be contaminated with trace metals. Preston et aL (1972) reported that the eastern Irish Sea (including Liverpool Bay) had the highest trace metal levels of all British coastal waters. The primary inputs to the Bay are the outflow from the River Mersey which contributes both particulate and dissolved trace metals, and a sewagesludge dumping ground in the eastern part of the Bay which adds primarily to the particulate fraction (Norton et al., 1984). Two specimens of the tope Galeorhinus galeus, were obtained through a sport fishery based at Conway, North Wales in July 1985. The fish, an immature 111 cm female and an adolescent 108.5 cm male, were caught several miles offshore in the western part of Liverpool Bay. Tissue samples were obtained from each fish and prepared for analysis using a modification of the wetdigestion technique used by Stevens & Brown (1974). 2 g (fresh wt) samples of selected tissues were digested in 11 ml of a nitric-perchloric acid mixture. When no solid material remained (48 h), the samples were made up to 50 ml with triple-distilled water. The prepared samples were then stored in polypropylene containers for later analysis. Analysis was carried out on a Perkin-Elmer 103 Atomic Absorption Spectrophotometer under recom-

0025-326X/87 S3.00+0.00 © 1987 PergamonJournalsLtd.

mended operating procedures (Perkin-Elmer 1972). In order to check on the purity of the chemicals used, a number of chemical blanks were run (10 ml HNO 3, 1 n~ HC1Q, 39 ml triple-distilled H20). There was no evidence of any contamination in these blanks (Table

1).

The tissues were analysed for up to 7 trace metals; Cu, Mn, Fe, Cd, Ni, Pb, Zn. During the analysis for Zn a fault developed with the equipment, and only half the samples could be run. The trace metal contents of the various tissues are given in Table 2. The data was transformed logarithmically for statistical analysis (to equalize the variances), and an analysis of variance carried out for each metal using the tissues as the source of variation. Table 3 lists the results of this data analysis. Significant differences between tissues were apparent for Cu, Mn, Fe, and Ni. Cu levels were highest in the skin and reduced in the gonads. Mn concentrations in the vertebrae were significantly elevated. Fe and Ni were both detected at high levels in the skin and gonads, and at reduced levels in the vertebrae. The high Fe concentration in the testes of the male is probably due to the increased vascularization of the testes which takes place during the onset of sexual maturity. The highest concentrations of each metal were generally associated with skin samples. This probably represents external contamination (i.e. adsorption on to the surface of the skin) rather than high levels within the tissues themselves. There was no significant difference between the levels of the various metals between male and female fishes (t-tests, p>0.05). However, Fe levels were TABLE1 Trace metal content of chemicals used (blanks), in ppm.

Cu

Mn

Fe

Cd

Ni

Pb

Zn

<0.02

<0.02

<0.05

<0.01

<0.02

<0.02

<0.02

193

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