Indian Journal of Geo-Marine Sciences Vol.44(8), August 2015, pp. 1200-1206

Heavy metals concentrations in brown seaweed Padina Pavonia (L.) and P. tetrastromatica at different beaches of Coast

Rashida Qari Institute of Marine Science, University of Karachi, Karachi 75270, [Email: [email protected]]

Received 18 February 2014; revised 25 June 2014

Present investigation was undertaken to know the levels of (Mg, Fe, Mn, Cu, Ni, Zn, Cr, Pb, Co, Cd and Hg) in the brown algae Padina pavonia and P. tetrastromatica collected from three coastal areas of Karachi,.. The concentrations of Mg, Fe, Mn, Cu, Ni, Zn, Cr, Pb, Co, Cd and Hg in digested samples of seaweeds were measured by Atomic Absorption Spectrophotometer (Varian AA-20). Concentrations of Mg, Cd and Co were highest at Buleji, Cu and Ni at Paradise Point and Fe, Mn, Zn, Cr, Pb and Hg were high at Nathia Gali. In both species of Padina high concentrations of heavy metals are due to untreated wastes that are discharging from different sources such as industries and houses in coastal areas. [Key Word: Heavy metal, brown seaweed, Buleji, Paradise Point and Nathia Gali, pollution]

Introduction Brown seaweeds are most effectively Padina pavonia and P. tetrastromatica used as indicator of pollution by certain heavy are benthic brown seaweed found abundantly in metals18. The potential of seaweed as metals intertidal areas particularly in tide pools of Buleji, indicator have been reported by various workers Paradise Point and Nathia Gali beaches of for brown seaweed13,19. Many brown seaweed Karachi coast. The coastal areas of Karachi are species are used as an indicator of heavy metal ecologically and economically important but pollution for example Fucus vesiculosus11,20. these coastal areas are facing many types of Basson and Abbas21 reported elemental pollution1-8. Marine pollution either natural or composition (Mg, Fe, Cd, Cr, Co, Mn, and Ni) of anthropogenic is a major threat to the health of fifteen seaweeds from the Bahrain coastline millions of people, marine animals and plants (Arabian Gulf). Many workers related to India especially benthic communities that seriously have also studied the trace metals distribution in impact the entire ecosystem. seaweeds22,23. Whyte and Engler24 studied Fe, Zn, The continental shelves of Pakistan Mn, Cr and Cu in marine algae of Burrard inlet, include Makran and Baluchistan coasts are off Stanley Park. Hussein et al.25 studied the Mg, thriving with natural resources of rich flora and Mn, Zn and Cu concentration in brown algae P. fauna9. Chemical composition of seaweed pavonia from Roushdy, Alexandria. Rajendran et undergoes marked variation in changing al.26 studied metal concentration (Mn, Fe, cu and environments i.e., the seasons, the habitats, and Zn) in seaweed from Tamil Nadu coast of India. depth at which they grow. It is a known fact that Due to rapid growth of population and industries accumulation of metal in seaweeds is related to resulted in the problem of pollution, especially of their concentration in water and it has been the coastal aquatic environment of Karachi. observed that it is also influenced by changing Extent of pollution has transpired the impetus to season10-13. Metals that enter the marine initiate a study on the biodeposition of heavy environment are taken up and accumulate in metals i.e., Mg, Fe, Mn, cu, Ni, Zn, Cr, plants (marine algae) and animals14. Algae are Pb, Co, Cd and Hg in seaweeds. This study was the primary producers, which possess a great undertaken, to gather information that will serve ability to accumulate heavy metals15. This has as baseline values of heavy metals in brown been reported that industrial discharges and often seaweed (P. pavonia and P. tetrastromatica) environmental factors may to metal pollution found along the coastal areas of Karachi. of seawater16. Metals are concentrated by a factor Seasonal variability is also studied in the metal of 30,000 to 50,000 as compared to their concentrations and relationship between heavy concentration in the ambient environments. metals concentrations in seaweeds and seawater. Seaweed absorbed elements like Na, K, Ca, Mg, Cl, Br, and I, from seawater and accumulated in Materials and Methods thallus. Seaweeds have high quantities of Mg and Both species of seaweeds Padina pavonia Fe (15-25%)14,17. and P. tetrastromatica and seawater were sampled from three exposed shores of Karachi coast i.e., Buleji, Paradise Point and Nathia Gali QARI: HEAVY METALS PADINA PAVONIA AND P. TETRASTROMATICA AT KARACHI COAST 1201 at low tide. These plants were carefully cleaned from mud debris and other epiphytes with filtered seawater and dried at 70 oC for 24 hours till a constant weight was achieved. Samples were then homogenized with a porcelain pestle and mortar to a powder form, sieved and stored in plastic bottle until further analysis. Digestion of samples was carried out as described by Denton and Burdon Jones18. Triplicate samples of both species of seaweed (1 gram) were digested with concentrated nitric acid (4 ml) and concentrated perchloric acid (2 ml) in 50 ml Teflon beaker (prewashed with nitric acid solution) covered with lid at 80 oC on a hot plate. After digestion and evaporation of acid, metal salt were re-dissolved in metal free deionized water and the final volume was made up to 100 ml in volumetric flask. Reagents blank were treated similarly as samples using same volume of acid and deionized water. In digested samples of seaweeds concentrations of Mg, Fe, Mn, Cu, Ni, Zn, Cr, Pb, Co, Cd and Hg were measured by Atomic Absorption Spectrophotometer (Varian, AA-20). All results in seaweeds are reported in µg/g except Mg in mg/g. The water samples were filtered using Fig. 1. Variation in magnesium concentration of seaweeds 0.45 µm membrane (Millipore) filter paper and 27, (mg g-1) and seawater (g l-1) at Karachi coast (1. Buleji 2. acidified with 0.1 N HCL for further treatment Paradise Point 3. Nathia Gali). 28. For the preconcentration of heavy metals the samples of seawater were chelated with pyrrolidine dithiocarbonate and then extracted with methyl isobutyl ketone (MIBK)28-31. The extracted sample was back extracted by evaporating the organic solvent and acidified with concentrated HCl. The Atomic Absorption Spectrophotometer (Varian, Model AA-20) was used to analyze the heavy metals (Mg, Fe, Mn, Cu, Ni, Zn, Cr, Pb, Co, Cd and Hg). All results of seawater are reported in mg l -1 except Mg, which is in g l-1.

Results and Discussion For the seasonal variation in heavy metals two brown species of seaweeds P. pavonia and P. tetrastromatica were studied, collected from three sites (Buleji, Paradise Point and Nathia Gali) of Karachi coast. In each species concentrations of eleven metals i.e., Mg, Fe, Mn, Cu, Ni, Zn, Cr, Pb, Co, Cd and Hg were estimated. Data reveals high variability in metals (Mg, Fe, Mn, Cu, Ni, Zn, Cr, Pb, Co, Cd and Hg) concentration in both species along the Karachi coast within and between seaweed species, sampling sites and collection time. Fig. 2. Variation in iron concentration of seaweeds (µg g-1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. Paradise Point 3. Nathia Gali).

1202 INDIAN J. MAR. SCI., VOL. 44, NO. 8 AUGUST 2015

The levels of metals concentration ranged Individually the highest concentration of metals from 1.21- 7.13 mg g-1 for Mg, 0.4 – 6.4 µg g-1 Cu, Zn, Cr, Pb, Co, Cd and Hg were found in P. for Fe, 0.11-0.8 µg g-1 for Mn, 0.011- 0.187µg g- Pavonia, Mg, Fe, Mn in P. tetrastromatica and 1 for Zn, 0.012- 0.17 µg g-1 for Cr, 0.024-0.158 Ni was equal in both species. Among the studied µg g-1 for Pb, 0.01- 0.11 µg g-1 for Cu, 0.016- metals Mg is the essential element of nitrogen 0.063µg g-1 for Ni, 0.004-0.11 µg g-1 for Co, metabolism in algae, was found in high 0.005-0.046 µg g-1 for Cd and 0.0001-0.004 µg concentrations (1.21- 7.13 mg g-1) in both species g-1 for Hg at the three sites Buleji, Paradise Point of seaweed than the other metals. Cd was found and Nathia Gali in both species (Padina pavonia in very low concentrations than the other metals, and P. tetrastromatica) where as levels of metals it was found in low range and showed less concentration in seawater ranged from 1.07-13.66 variation. The concentrations of Mg, Cd and Co mg g-1 for Mg, 0.25 – 1.64 µg g-1 for Fe, 0.06- were high at the Buleji coast. Cu and Ni were 0.31 µg g-1 for Mn, 0.091- 0.76µg g-1 for Zn, high at Paradise Point and Fe, Mn, Zn, Cr, Pb and 0.13- 0.73 µg g-1 for Cr, 0.25-0.63µg g-1 for Pb, Hg were high at Nathia Gali (Figs. 1-11). It is 0.047- 1.22 µg g-1 for Cu, 0.037- 0.42µg g-1 for commentable that small variations in the Co, Cd Ni, 0.061-0.45 µg g-1 for Co, 0.017-0.38 µg g-1 and Hg levels were found among species, site and for Cd and 0.00001-0.0002 µg g-1 for Hg at the collection time, indicating that no major source of three sites Buleji, Paradise Point and Nathia Gali these metals occurred in Karachi coastal water. (Figs. 1-11). The completely randomized design with nested treatments analysis of variance (ANOVA) model The results show high variability in was used to test the significant differences of metal concentrations between sites and between heavy metals in both seaweed species and species. Both species P. pavonia and P. seawater between sites and months (Table 1). tetrastromatica were showed high concentration of Fe, Mn and Hg at all studied beaches as compared to seawater (Figs. 2, 3, 11). While the concentrations of Mg, Zn Cr, Pb, Cu, Ni, Co and Cd was high in seawater (Figs. 1, 4, 5, 6, 7, 8, 9, 10 and 11 respectively).

Fig. 4. Variation in zink concentration of seaweeds (µg g-1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. Paradise Point 3. Nathia Gali). Results show that there were high significant variations found between sites for Mg (F= 30.05), Fe (F=15.94), Mn (F=5.16), Cr (F=5.11), Cd Fig. 3. Variation in manganese concentration of seaweeds (µg g-1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. (F=5.16) and Hg (F=18.30). Significant variations Paradise Point 3. Nathia Gali). were also found in between species for Fe (F=12.01), Zn (F= 4.71), Cu (F= 11.20), Cd (F= QARI: HEAVY METALS PADINA PAVONIA AND P. TETRASTROMATICA AT KARACHI COAST 1203

4.02) and Hg (F=70.38). Whereas no any significant variations were found between months for any metal studied in both species and seawater. The Table 1 show the accumulation of metals in both species was different at different sites and that could be related to extent of pollution at that particular site. Correlation between heavy metals concentrations observed in seaweed species was mostly positive significant for example positive and significant correlation was found in between metals Pb and Zn (r2 = 0.492), Ni and Hg (r2 = 0.508) in P. pavonia, Cd and Pb (0.641 ) in P. tetrastromatica and Co and Cr (r2 =0.664) in seawater.

Fig. 6. Variation in lead concentration of seaweeds (µg g-1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. Paradise Point 3. Nathia Gali). Metal Source DF F P Mg Sites 2 30.05*** 0.000 Species 1 0.28 0.601 Month 11 0.39 0.954 Fe Sites 2 15.94*** 0.000 Species 1 12.01** 0.001 Month 11 0.99 0.468 Mn Sites 2 5.16** 0.009 Species 1 0.40 0.528 Month 11 0.78 0.657 Zn Sites 2 0.23 0.798 Species 1 0.71 0.034 Month 11 0.7 0.716 Cr Sites 2 5.11** 0.009 Species 1 0.91 0.345 Month 11 0.78 0.656 Pb Sites 2 0.71 0.497 Fig. 5. Variation in concentration of seaweeds (µg Species 1 0.58 0.449 g-1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. Month 11 1.68 0.101 Paradise Point 3. Nathia Gali). Cu Sites 2 4.79* 0.012 The correlation in between heavy metals Species 1 11.20** 0.001 concentrations observed in seaweed species and Month 11 1.31 0.240 seawater was negative and insignificant except Ni Sites 2 0.38 0.682 positive and significant correlation (r2 = 0.498) Species 1 0.05 0.830 Month 11 0.69 0.747 was exist in between Cd content of P. Co Sites 2 1.50 0.232 tetrastromatica and Cd content of seawater. Species 1 0.20 0.657 Mg, Fe and Mn were detected in higher Month 11 0.66 0.769 range in both alga like most other algal species of Cd Sites 2 26.66*** 0.000 same region2,5. While the concentrations for Mg Species 1 4.02* 0.050 Zn, Mn and Cu obtained in present work were Month 11 0.36 0.967 Hg Sites 2 18.30*** 0.000 low when compared with the results of Hussein et 25 Species 1 70.38*** 0.000 al. from Roushdy, Alexandria for the P. pavonia Month 11 0.24 0.993 22 species and Ganesan et al. from Gulf of Table 1. Analysis of variance (ANOVA) of heavy metals in Mannar, Bay of Bengal for the P. tetrastromatica. two Species of seaweed (Padina pavonia and P. tetrastromatica) from Karachi Coast (* = P < 0.05, ** = P < 0.01, *** = P < 0.001). 1204 INDIAN J. MAR. SCI., VOL. 44, NO. 8 AUGUST 2015

The result for iron and magnesium obtained in present work were similar like the previous study32. In present study the values of metals (Mg, Mn, Cu, Ni, Zn, Mg, Fe, Cr, Pd, Co, Cd and Hg) observed in P. pavonia and P. tetrastromatica were lower than values found in the local species of Great Barrier Reef, Australia18.

Fig. 8. Variation in nickle concentration of seaweeds (µg g- 1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. Paradise Point 3. Nathia Gali).

Fig. 7. Variation in copper concentration of seaweeds (µg g- 1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. Paradise Point 3. Nathia Gali). Values obtained in the present study for Mn, Cu, Ni, Zn, Fe, Pb and Cd content were very low when compared with the previous study done in Hong Kong33. The metals concentration patterns in decreasing order was Mg> Fe> Mn> Zn> Cr> Pb> Cu> Ni >Co > Cd > Hg in both species where as Mg> Fe> Zn> Cr> Pb> Mn> Cu> Co >Ni > Cd > Hg in seawater. A similar trend in concentration of metals was found in present study, is also found at India coast23,26. In general the higher metal concentration were found in the pre and post monsoon season and low in northeast and southwest monsoon periods, this is also true for seaweed biomass that some species of seaweed were not found during summer monsoon period34-36. The causes for the Fig. 9. Variation in cobalt concentration of seaweeds (µg g- 1) and seawater (mg l-1) at Karachi coast (1. Buleji 2. variations found in metal concentration in both Paradise Point 3. Nathia Gali). seaweeds species and seawater due to higher Mg is high in present study due to two reasons terrestrial inputs caused by increased summer rain first it is major element of seawater and easily fall with a consequent increase in suspended accumulated in seaweeds second rapidly growing particles with adsorbed metals. chemical industries and refineries near the coastal QARI: HEAVY METALS PADINA PAVONIA AND P. TETRASTROMATICA AT KARACHI COAST 1205 areas of Karachi and discharging their chemical absorbed iron from their surrounding effluent in seawater. environment as compared to other trace metals except Mg. The bioaccumulation of Mn is due to seaweeds are better representative of Mn in seawater than other organisms. High concentrations of Zn were because algae from the seawater readily concentrate Zn. The present study indicates that due to continuous exposure to pollution the accumulation of heavy metals in seaweed can

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