SEAWEEDS AS BIOINDICATORS OF HEAVY METALS POLLUTION IN TARUT BAY SAUDI ARABIA

Mohamed Guitouni* 1,2 , Ali Al Madan 2 and Sami Shabeeb Al-Shabeeb 2 . 1. National Institute of Research and Physico-Chemical Analysis, Technological Pole Sidi Thabet 2020, Aryanah, Tunisia. 2. Fisheries Research Center, Eastern Province, Kingdom of Saudi Arabia. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


1096
In this study, an assay was made to find the possibility of using the seaweeds as biomonitoring agents to evaluate various heavy metals such as As, Hg, Ni, Fe, Cr and Zn which are released from the activity of petroleum industries, discharge of industrial waste and oil spills from ships (Literathy et al., 2002). Seaweeds samples are taken from Tarut Bay, Eastern Province-Saudi Arabia,

Material and Methods:-
The samples of seaweeds are collected from Tarut Bay, Eastern Province-Saudi Arabia, during the period from April 2015 to june 2015. Tarut Bay is located along the coastline of the Arabian Gulf. Tarut Bay extends from the King Abdulaziz seaport of Dammam and end at Ras Tanura, covering an area of 410 k 2 as shown in Figure 1. The samples of seaweeds have been used to determine the concentrations of six heavy metals: Arsenic, Nickel, Zinc, Iron, chromium and mercury.
Seaweeds have been dried in electrical oven. Then digests with 8 ml HNO3 (65%) in a microwave mineralization (microwave Milestone Ethos one). The heavy metals were determined by the Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES ; Varian 720-ES) and they were quantified in ppm. ( Sawidis et al., 2001;Brown et al., 1999;Al-Homaidan, 2008) Mercury analysis has been realized using the Direct Mercury Analyser (DMA-80, Milestone).

Results:-
The analysis of seaweeds samples for heavy metals accumulation showed that seaweeds have a high capacity to accumulate heavy metals present in the marine environment. The concentration of heavy metals accumulated differ from one plant to another, we see that the Liagora viscida species accumulate more heavy metals than other species. The concentrations of heavy metals accumulated by seaweeds is shown in Table 1 and Figure 2. Zn Figure 2:-Accumulation of heavy metals in seaweeds (ppm) We calculated also the capability of absorbing and accumulating (in percent) for the six heavy metals (As, Cr, Ni, Hg, Zn, Fe) by seaweeds studied. The results are presented in Figure 3 0  In this study, the results find for different species of seaweeds showed the presence of nickel, iron and mercury with less concentrations than arsenic, zinc and chromium. we see that the Liagora viscida species accumulate more heavy metals than other species. It was observed that arsenic was the most element accumulated in the different species of seaweeds (from 11 ppm to 54 ppm in different spesies for seaweeds), this can be explained by that the marine organisms normally contain arsenic residues ranging from less than 1 to more than 100 mg/kg, predominantly as organic arsenic species such as arsenosugars (macroalgae) and arsenobetaine (invertebrates and fish). The bioaccumulation of organic arsenic compounds, after their biogenesis from inorganic forms, occurs in aquatic organisms. Bioconcentration factors (BCFs) in freshwater invertebrates and fish for arsenic compounds are lower than for marine organisms.
It clearly demonstrated that the seaweeds are considered valuable indicators because of their accumulation capacity of heavy metals, and can we used the seaweeds in phytoremediation (Salt et al., 1998) to absorb and remove contaminants from polluted soil and water is an efficient and friendly mechanism for the environment, such as mangrove (Avicennia marina) (

Conclusion:-
We confirm in this study that seaweeds can used as biomonitoring agents to evaluate-heavy metals pollution in marine environment. And they are considered valuable indicators because of their accumulation capacity of heavy metals. Seaweeds can be used in the phytoremediation system for cleaning the marine environment from pollutant and especially from heavy metals and can be used also as biological filters for the water used in fish farm.