An Assessment on the Coastal Seawater Quality of the Gulf of Suez, Egypt

The present study focused on water quality assessment of 14 hotspot locations in the Gulf of Suez by measuring the physicochemical parameters seasonally during 2016. The results of investigated area revealed that, the annual mean range of water was: temperature (21.91˚C - 29.22˚C), pH (7.64 - 7.78), salinity (38.71‰ - 42.74‰), dissolved oxygen (6.09 - 8.78 mgO 2 /l,) oxidizable organic matter (1.4 - 5.4 mg/l), biological oxygen demand (1.14 - 3.94 mgO 2 /l), total suspended solids (18.56 - 37.69 mg/l), ammonia (13.51 - 494.41 µg/l), nitrite (1.261 - 151.76 µg/l), nitrate (7.11 - 487.85), dissolved inorganic phosphate (2.22 - 53.26) and silicate (19.83 - 347.61 µg/l). The N:P ratio fluctuated between 4.21 and 1214.61 with the main value of 81.16 indicating that the different sites in the northern part of the Gulf of Suez are P-limited. Based on the Principal Component Analysis Data, the stations locating in the Northern and Southern side of the Gulf of Suez are relatively good water quality; meanwhile, water quality of the other stations locating in the northern side of the Gulf of Suez is found slightly polluted to a different degree coincided with an increase in the human activities in each of these locations.

both natural and anthropogenic processes. Generally, water quality information is very important in supporting the planning and management of coastal and marine areas under the influence of massive human activities. The Gulf of Suez extends around 280 km toward the north, ending at the City of Suez, which is the entrance to the Suez Canal. It is relatively shallow, with a maximum depth of around 64 m. It has a relatively flat base with a depth extending somewhere in the range of 55 and 73 m [3]. The coastal region of the Gulf of Suez is one of the most densely industrialized zones in Egypt. The sources and reasons of water contamination in the Gulf of Suez are exposed to different wellsprings of contamination that can be classified into sewage, organic solids, heavy metals, oils, nutrients, sediment mobilization, and litter. The mid-western side is situated under the immediate impact of sewage wastes and petrochemical effluents of the Ras-Gharib city. Whereas, the eastern (Sinai Peninsula) and southern (El Tour city) sides are affected by the human activities. Indeed, the water quality of the Gulf of Suez was monitored in previous studies [4] [5] [6] [7] [8]. The main objectives of the present study were set to study the water quality of the Gulf of Suez by measuring of physical and chemical characteristics; water temperature, dissolved oxygen (DO), oxidizable organic matter (OOM), pH, salinity, ammonia, nitrite, nitrate, reactive phosphate and reactive silicate in surface water.
Principal component analysis (PCA) was used to assess water quality in the Gulf of Suez as the main requirement for environmental and technical management of the Gulf of Suez, and consequently to minimize or mitigate the adverse environmental effects of human, industrial and maritime activities to allow sustainable use of the marine water resources.

Study Area and Sampling
Fourteen coastal sampling stations were selected to represent the different locations situated under the direct effect of human activities, public resort beaches and some protected area ( Figure 1). Duplicate water samples from each station were collected seasonally during 2016 at 25 cm depth below the water surface to avoid the floating materials using a high quality and Purified PVC Niskin's bottle to estimate hydrochemical parameters (i.e., water temperature, salinity, pH, dissolved oxygen) and eutrophication parameter (chlorophyll-a, nutrient salts).

Sample Analysis
The water sample was immediately sub-sampled for the following determinations in sequence as follows: i) Water temperature, pH and salinity were measured using the Conductivity, Temperature, and Depth (CTD) (YSI 6000) after earlier calibration.
ii) Fixation of the Dissolved oxygen is commenced immediately in the field; samples for biochemical oxygen demand (BOD 5 ) were incubated in the laboratory for five days at 20˚C and then determined by Winkler's method [9] [10].  iii) Oxidizable organic matter (OOM) was determined according to the method described by FAO (Food and Agriculture Organization) [11]. iv) Chlorophyll-a (Chl-a) was analyzed according to method given by Strickland and Parson's [9]. v) TSM was determined according to APHA (American Public Health Association) [12].
vi) Water samples for total ammonia nitrogen determination were fixed in the field and determined, using the indophenol blue technique [13].
vii) Dissolved inorganic-N (DIN) (NO 2 -N and NO 3 -N), reactive phosphate ( 3 4 PO − -P) and silicate (SiO 4 -Si) were determined in filtered Seawater samples according to the methods described by Grasshoff et al. [11] viii) DIN was calculated by summation of the inorganic-N forms: vi) TN and total phosphorus (TP) were determined according to the technique described by Koroleff [14] and modified by Valderrama [15].
The developed color was measured at different wavelengths using a spectrophotometer (JANEWAY6800 double-beam spectrophotometer). Synthetic samples and/or reference materials of different nutrient salts were used during analysis to get the calibration curve and for the precision and the accuracy as quality control tools. for salinity, 7.64 -7.78 for pH, 6.09 -8.78 mg/l for DO, 1.14 -3.94 mgO 2 /l for BOD, 1.4 -5.4 mgO 2 /l for OOM. The annually averages for temperature, salinity, pH, dissolved oxygen, biological oxygen demand, and oxidizable organic matter respectively, were found in agreement with UNEP and PERSGA [16]. Variations and fluctuation of salinity may be attributed to temperature and wastewater discharge. The seawater of the study area was found well-oxygenated; the relative increase in BOD at a station (W 9 ) could be the result of the relative increase of human impact at this location. Meanwhile, the presence of anthropogenic sources near to stations (W 8 -W 13 ) is responsible principally for the relative increase in the OOM. The data of the present study when compared with those of coastal water quality standards suited to marine ecosystem [17], revealed that the present status of the Gulf of Suez seawater is locating within these standards of the acceptable levels since it should be taken into account that permissible deviation is up to >22 from the normal temperature, >0.2 in pH unit, and >5% overage seasonal salinity.

Chlorophyll-a and Total Suspended Matter
The regional values of chlorophyll-a, total suspended matter, and nutrient salts are presented graphically in (Figure 3) and illustrated in ( Table 2). The absolute values varied between 0.11 -3.66 µg/l for Chl-a and 18.56 -37.69 mg/l for TSM

Nutrient Salts
The obtained levels of nitrogen and phosphorus forms are given in (Table 2) and demonstrating graphically at (Figure 3) [19]. The current study represented that an increase in the amounts of total nitrogen and total phosphorus was accompanied by a decrease in salinity values. This illustrates the role of industrial and sewage effluents in providing the coastal seawater with nitrogen and phosphorus forms. The DIN/DIP ratios showed very wide fluctuations ranging from 4.21 -1214 giving the overall mean nutrient salts. They deviate from that of the normal case of the Red field (N/P is 16:1) coincided with the relative increase of anthropogenic activity. The results determined by Chraudani and Vighi [20], indicated that the marine algae are P-limited at P:N ratio < 6 and N-Limited at ratio > 4.5; in the range of 4.5 -6; the two nutrients are close to their optimum assimilative proportion. Extremely variability of the N/P ratio is omitted to a land-based runoff as mentioned by Dorgham et al. [21].  (Table 3). The application of frequency distribution analysis represents the ranges of the eutrophication index as oligotrophic, mesotrophy and eutrophication as mentioned by Ignatiades et al. [24] ( Table 4). The Enrichment index values for the fourteen stations of the Gulf of Suez seawaters are given in (Figure 4). The results demonstrate that the coastal seawaters of the Gulf of Suez varied from oligotrophy   Table 4. Ranges of the Eutrophication index "Oligtrophy, Mesotrophy and Eutrophication" resulting from the application of frequency distribution analysis.  oligotrophy. The Enrichment index values of W 8 , W 9 , W 10 , and W 11 indicate an increase of the drainage effluents at these locations.

Statistical Analysis
A correlation matrix was displayed for surface coastal waters of the Gulf of Suez (Table 5)    Analyzing the data was performed according to the principal component analysis using the statistical package for the social sciences SPSS [25]. The output data showed four factors with eigenvalues higher than one, which affected water parameters distribution, association and sources with cumulative covariance of 87.51% (Table 6, Figure 5).    polluted to a different degrees (0.04) -(1.87) coincided with an increase in the human activities in each of these locations. W7 is located in Al Adabbia Harbour and W 8 in Attaqa, which are subjected to ships activities, whereas station (W 9 ) was found more polluted station (WQI = 1.87) as a result of sewage flow at W 9 station. The quality of waters of W 10 was affected with many industrial effluents coming from Attaqa Company for Electricity and Miratex for Textile. W 11 and W 13 are subjected to domestic effluents of the Suez Government. Station W 14 is located in port Tewfik Harbour that is affected with the activities of ships.

Conclusion
The present investigation gives some significant information about the ecological nature of the Gulf of Suez. The obtained results feature that, there is a pronounced variation in most of the water quality parameters with variation in season and geographic location. The water quality in the Gulf of Suez is influenced by the released from point wellsprings of contamination. The redesign spatial strategy of monitoring stations is required to assess the effect of hydro-advancement extends and assesses its impact on the studied area.