Table
2 illustrates the average concentration of some elements in red, green and brown seaweed species. The present results showed the same elements ordering in seaweed species, except in brown seaweeds, iron (Fe) seems to be higher than zinc (Zn); F > Na > K > Ca > Mg > Zn > Fe > Mn > Co > Cd > Ni > Cu > Cr. Also, red seaweed species contain the highest iron (789.00 ± 40.02 μg/g) and zinc (1,088.67 ± 1,998.25 μg/g) average concentrations. In contrast, brown seaweeds have the lowest iron (40.26 ± 4.05 μg/g) and zinc (20.91 ± 1.36 μg/g) average ones. Whereas, it was stated that the elements content in seaweeds may be dependent on various environmental factors including; concentrations of elements in water (Andrade et al.
2004), interactions between elements, salinity, pH, light intensity, and metabolic factors such as dilution of element contents due to seaweed growth (Zbikowski et al.
2006). Also, concentrations of elements in seaweeds are regulated to a large extent by metabolic requirements (Zbikowski et al.
2006). Red, green, and brown seaweeds give Ca/Mg averages of 2.23 ± 0.98, 5.41 ± 4.10, and 2.89 ± 0.58, respectively (Table
2). Thus, green seaweeds supply better calcium sources than the red and brown ones. Accordingly, the high significant correlation between calcium and magnesium (
r = 0.4969;
p < 0.05) may be accompanied with the substitution of calcium by magnesium in calcite seaweed's component. Also, green seaweeds show smaller average Na and K than red and brown seaweeds (Table
2). Whereas, sodium and potassium in the present data are strongly related (
r = 0.4677;
p < 0.05) as they play an important role in the electrolyte balance (Krishnaiah et al.
2008). It was mentioned that seaweeds living in ocean containing predominantly Na and their salts. Some seaweed accumulates more K and their salts than Na. However, potassium is an essential element for the growth and metabolic activities of plants and seaweeds (Sivakumar and Arunkumar
2009). The K/Na balance is regarded to be important for people who take diuretics, to control hypertension and suffer from excessive excretion of potassium (Cutler
2006; Zillich et al.
2006). Elements are also important as constituents of bones, teeth, soft tissues, hemoglobin, muscle, blood, and nerve cells, and are vital for overall mental and physical well being (Miyake et al.
2005; Kuda and Ikemori
2009).
