Mobility of carbohydrates, proteins, phenol and eutrophication assessment in a brackish Egyptian lake; predicted equations

ABSTRACT

Although great efforts have been devoted in assessing the ecological risks in aquatic environments, a lack of information is still present. An integrative approach was proposed concerning the mobility of carbohydrates, proteins and phenol among water, sediments and macrophytes in relation to the physical, chemical and geochemical parameters of Lake Mariout. Total carbohydrates, proteins and phenol showed averages of 6.80 mg L⁻¹, 116.90 mg L⁻¹ and 19.46 µg L⁻¹; 89.82 mg g⁻¹; 29.21 mg g⁻¹ and 1.80 µgg⁻¹; and 60.80 mg g⁻¹, 15.27 mg g⁻¹ and 9.29 mg g⁻¹ in water, sediments and macrophytes, respectively. Protein/carbohydrate ratios in sediments were used as the trophic indicator. This study cleared out that all stations had ratios (<1) refereeing to aged organic matter. Station 6 indicated fresh organic matter. Moreover, the ratio of total organic carbon to total nitrogen (TOC/TN) suggested a primarily marine origin at eleven stations (<10) and a mixture of terrestrial input and marine materials (>10) at stations 1 and 7 located in the North-West Basin. Relatively high phenol concentrations of 54.5, 38.25 and 45.37 µgL⁻¹ in water were measured at stations (3 & 5) located in the Main Basin, and station 11 located at El-Qalaa drain, respectively. The partition coefficient of phenol (K_d) varied from 0.053 to 0.199 (<1 Lg⁻¹) revealing high mobility and an underground disposal facility. The low biodiversity of phytoplankton (38 spp.), seagrasses (4 spp.) and seaweed (3 spp.) inside the lake reflected the impact of wastewater discharged. Two phytoplankton blooms were observed at stations 3 and 7. According to the Diversity Index of Boyd, all Mariout stations (<4) are moderately polluted. Multivariate analyses were adopted to describe the lake chemistry. This study gives a conceptual framework helps decision-makers to express the problem of sustainability at Lake Mariout.

KEYWORDS:

• Egypt
• Lake Mariout chemistry
• macrophyte
• phytoplankton
• trophic state

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No potential conflict of interest was reported by the author(s).