Water quality of two semi-closed areas in the United Arab Emirates Coast along the Arabian Gulf:a comparative study

A comparative study was carried out between the two biggest creeks along the Arabian Gulf coast of the United Arab Emirates to evaluate impacts of sewage and industrial effluents on their hydrochemical characteristics. Surface and bottom water samples were collected from Abu Dhabi and Dubai creeks during the period from October 1994 to September 1995. The hydrochemical parameters studied were: temperature (21.10-34.00°C), salinity (37.37-47.09%), transparency (0.50-10.0 m), pH (7.97-8.83), dissolved oxygen (1.78-13.93 mg/l) and nutrients ammonia (ND- 13.12,ug-at N/1), nitrite (ND-6.66 ,ug-at N/1), nitrate (ND- 41.18 ,ug-at N/1), phosphate (ND- 13.06 ,ug-at P/1), silicate (0.68-32.50 ,ug-at Si/1), total phosphorus (0.26- 21.48 ,ug-at P/1), and total silicon (0.95- 40.32 ,ug-at Si/1). The present study indicates clearly that seawater of Abu-Dhabi Creek was warmer (28.l2°C) than Dubai (27.56°C) resulting in a higher rate of evaporation. Owing to more evaporation, salinity levels showed higher levels at Abu Dhabi (43.33%) compared to Dubai (39.03%) seawater. The study also revealed higher secchi disc readings at Abu Dhabi Creek (4.68 m) as compared to Dubai Creek (2.60 m) suggesting more transparency at Abu Dhabi Creek. Whereas, seawater of Dubai exhibited higher levels of pH (1.03 times), and dissolved oxygen (1.05 times) than Abu Dhabi seawater due to an increase in productivity. Meantime, seawater of Dubai showed higher tendency to accumulate ammonia (8.22 times), nitrite (10.93 times), nitrate (5.85 times), phosphate (10.64 times), silicate (1.60 times), total phosphorus (3.19 times), and total silicon (1.54 times) compared to Abu Dhabi seawater due to the enrichment of seawater at Dubai with domestic sewage waters which has distinctly elevated the levels of the nutrient salts particularly in inner-most parts of the creek leading to eutrophication signs. The changes occurred in the receiving creek water of Dubai as a result of waste-water disposal that have also reflected on the atomic ratios of nit: Effect of pollution rogen: phosphorus: silicon

Coral spawning in the Gulf of Oman and relationship to latitudinal variation in spawning season in the northwest Indian Ocean

Despite a wealth of information on sexual reproduction in scleractinian corals, there are regional gaps in reproductive records. In the Gulf of the Oman in the Arabian Sea, reproductive timing was assessed in four common species of broadcast spawning corals using field surveys of gamete maturity and aquarium observations of spawning activity. The appearance of mature gametes within the same month for Acropora downingi, A. hemprichii, Cyphastrea microphthalma and Platygyra daedalea (≥ 75% of colonies, n = 848) indicated a synchronous and multi-specific spawning season. Based on gamete disappearance and direct observations, spawning predominantly occurred during April in 2013 (75- 100% of colonies) and May in 2014 (77-94% of colonies). The difference in spawning months between survey years was most likely explained by sea temperature and the timing of lunar cycles during late-stage gametogenesis. These reproductive records are consistent with a latitudinal gradient in peak broadcast spawning activity at reefs in the northwestern Indian Ocean which occurs early in the year at low latitudes (January to March) and progressively later in the year at mid (March to May) and high (June to September) latitudes

Petroleum hydrocarbons along the Arabian Gulf coast of United Arab Emirates

10-16<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">In addition to 20 sediment samples, surface and bottom seawater samples were collected monthly during 1993-1994 at 24 sampling stations. Oil concentrations in seawater were below 13 <span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">μg 1-1 and ranged from 0.19 to 12.95 <span style="font-size:14.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">μg 1-1 Comparatively higher concentration levels (5.97 <span style="font-size: 14.0pt;line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:="" hiddenhorzocr;color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;="" mso-bidi-language:hi"="" lang="EN-IN">μg 1-1) were recorded at off-shore stations which are located close to oil tankers' routes in the Arabian Gulf. The other stations, on the other hand, which represent coastal waters of the United Arab Emirates showed lower concentration levels (4.18 <span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">μg 1-1<span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">). Oil pollution levels were also higher at surface layers (4.91 μg 1-1) as compared with bottom layers (3.70<span style="font-size:14.0pt;line-height:115%; font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN"> μg 1-1) reflecting higher rate of oil dissolution at surface layers. The presence of oil pollution, on the other hapd, at bottom layers was probably due to: 1) the role of bottom sediments on the enrichment of overlying water layers by hydrocarbons, 2) the role of precipitation of thick residual oils after evaporation of lower-boiling-point components of the oil and the turbulence of water column. The present study revealed comparatively lower levels (3.93<span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN"> μg 1-1<span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">) and lower vertical gradients <span style="font-size: 14.0pt;line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:="" hiddenhorzocr;color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;="" mso-bidi-language:hi"="" lang="EN-IN">(1.17 μg 1-1) for the whole area in the summer season compared to the winter season (4.18 and 1.64 μg 1-1, respectively) as a result of a maximum rate of evaporation of lower boiling-point components of the oil and sinking of thick residual oils during summer months in addition to the intensity of tanker traffic at the time of sampling. Sediment analysis for petroleum hydrocarbons suggested the presence of appreciable quantities of petroleum hydrocarbons in sediments, particularly those from off-shore areas (7.0<span style="font-size:14.0pt;line-height:115%; font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN"> μg-1). However, the levels reported here and in particular those for coastal areas (6.5 μg-1) were below 10 μg-1of dry weight which correspond to hydrocarbon concentrations in coastal areas considered unpolluted.</span

Chemistry of the mangrove waters and sediments along the Arabian Gulf shoreline of the United Arab Emirates

224-229A study was carried out in order to study and characterize chemically the natural forests of mangrove ecosystems (Avicennia marina) along the shoreline of the United Arab Emirates. The results for the hydrochemical parameters like salinity, pH, DO, BOD, and nutrient salts revealed higher values and more pronounced variations in the mangrove water compared to nearby creeks indicating decreasing trend. Among mangrove areas, Umma al-Quwain is characterized by its higher dissolved oxygen, pH, phosphate, and lower BOD. ammonia and nitrate. The mangrove water of Khor al-Khuwair was characterized by its higher salinity BOD, ammonia, nitrite, nitrate, and silicate and lower dissovled oxygen, pH, and phosphate. The results for petroleum hydrocarbons in mangrove water indicated the presence of hydrocarbons in all samples. However, the mean hydrocarbons concentration in seawater (3.9μg/l) was almost similar to the concentrations in the coastal water of the Arabian Gulf, clearly revealing the absence of high concentrations. Sediment analysis for organic carbon contents indicated higher values in mangrove sediments (1.1-2.8 times) than the nearby creeks. The results showed that all values were below 10 μg/g of dry weight which correspond to hydrocarbons concentrations in coastal areas considered <span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">unpolluted.</span

Environmental characteristics of the United Arab Emirates waters along the Arabian Gulf : Hydrographical survey and nutrient salts

225-232<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Surface and bottom seawater samples were collected monthly from October 1993 to September 1994 at twenty-four stations. The levels of different parameters were in the range of : temperature (16.90-34.60°C), salinity (35.2-44.0×10-3 ),transparency (0.5- 13.0 m), pH (7.91-8.60), dissolved oxygen (3.63-9.02 mg/l), biological oxygen demand (0.05-6.11mg/l), ammonia (ND- 15.32μg-at N/l), nitrite (ND-5.18μg-at N/l), nitrate (0.07-14.32μg-at N/l), phosphate (0.01- 10.2 μg-at P/l), and silicate (0.4-26.5μg-at Si/l). The patterns of distribution indicated insignificant differences between surface and bottom layers due to the shallowness of the area, turbulence of the water column, and effects of sewage wastewaters. Water temperatures exhibited their lowest average value in the winter season and the highest in the summer season. The lowest averages of salinity, transparency, pH, and dissolved oxygen were measured in the summer season. Whereas, the highest averages for these parameters were observed in the winter season. Except for nitrate and phosphate, insignificant differences between average values of other nutrient salts in the summer and winter seasons were observed. Nitrate and phosphate showed lower average values in the summer season compared to the winter season due to the increase in the rate of uptake by phytoplankton which was more abundant in the summer season. Horizontal patterns of distributions for hydrographic parameters revealed only an increase for transparency and a decrease for biological oxygen demand in a seaward direction. Except for Sharjah creek, no distinct horizontal patterns of distributions for nutrient salts were observed. At Sharjah, most of the nutrient salts decreased in a seaward direction due to the presence of effective sewage pollution sources inside the creek. The atomic ratio of the elements N: P: Si were similar in Abu-Dhabi, Umm al-Quwain, and Ras al-Khaimah areas, but with lower values in Sharjah. It is concluded that the discharge of sewage and industrial wastes has affected the quality of  seawater inside some semi-enclosed areas, especially Sharjah creek, as indicated by the increase in the levels of biological  oxygen demand and the elevation in the concentrations of the nutrient salts.</span

بعض الخصائص الهيدروكيميائية لمياه دولة الإِمارات العربية المتحدة المطلة على الخليج العربي وخليج عمان

Surface and bottom water samples were collected from the United Arab Emirates waters along the Arabian Gulf and the Gulf of Oman during the period from October 1993 to September 1995. Samples were analyzed for temperature (21.1-33.5oC), salinity (35.86-43.20%), pH (7.94-8.40), transparency (4.5-17.5 m), dissolved oxygen (3.94-8.72 mg/1), ammonia (ND-22.7 ug-at N/l), nitrite (ND-2.16 (ug-at N/l), nitrate (ND-18.12 ug-at N/l), phosphate (0.01-4.22 ug-at P/l), and silicate (0.62-15.38 ug-at Si/1). The levels and distributions of the hydrochemical parameters in the investigated area showed that the Arabian Gulf seawater exhibited higher salinity (1.07 times), and ammonia (1.60 times) compared to the Gulf of Oman waters. Meantime, the Gulf of Oman waters were more transparent (1.30 times), and more oxygenated (1.07 times) . Moreover, seawater at the Gulf of Oman showed a tendency to concentrate nitrite (1.25 times), nitrate (1.72 times), phosphate (1.40 times), and silicate (1.06 times) which reveal relatively oligotrophic conditions in the Arabian Gulf waters. The Calculated atomic ratios of the elements P:N:Si in seawater of the Arabian Gulf and the Gulf of Oman were, particularly in the Gulf of Oman water, different from Redifield ratio and indicated that inorganic phosphorus was the limiting factor.تمت دراسة التغيرات الفصلية والمكانية لبعض الصفات الهيدروكيميائية مثل دوجة الحرارة - الملوحة - النفاذية - الأس الهيدروجيني - الأكسجين المذاب - الأملاح المغذية ( الأمونيا - النيتريت - النيترات - الفوسفات - السيليكات ) في مياه دولة الإِمارات العربية المتحدة المطلة على الخليج العربي وخليج عمان خلال الفترة من أكتوبر1993 وحتى سبتمبر1995 . أوضحت الدراسة وجود تغيرات فصلية ومكانية واضحة في معظم الصفات الهيدروكيميائية وخصوصاً درجات الحرارة - الملوحة وبعض الأملاح المغذية . أوضحت الدراسة أيضاً ارتفاع درجات الملوحة وارتفاع تركيز الأمونيا في مياه الخليج العربي عنها في مياه خليج عمان وبالعكس تميزت مياه خليج عمان بزيادة تركيز الأكسجين المذاب ومعظم الأملاح المغذية مثل النيتريت - النيترات - الفوسفات "السيليكات مما يدل على زيادة إِنتاجية مياه الدولة المطلة على خليج عمان . أوضحت الدراسة أيضاً أن نسب النيتروجين والفسفور والسيلكون في مياه الدولة بوجه عام اختلفت خصوصاً في منطقة خليج عمان عن النسب العادية ، وقد دلت هذه النسب على أن الفسفور هو الامل المحدد في المنطقة