Determination of Some Micro-Nutrient Salt Concentrations of Al-Nawras Lagoon Surface Waters at Jeddah Coast on the Red Sea

Al-Nawras lagoon is a semi-enclosed shallow basin; it is located in the middle part of the northern Cornish of Jeddah coastal area, Saudi Red Sea coast. In this study, the micro-nutrient salts of the surface waters of the lagoon were seasonally investigated between autumn 2006 and summer 2007. Five stations were appointed, and the level contents of nitrate, nitrite, ammonia, phosphate and silicate were determined. The study revealed that the highest levels of temperature and salinity were found between stations 2 and 4 due to the low water exchange between the lagoon and the open sea as those stations are located in the middle of the lagoon; meanwhile lower levels of temperature and salinity were found at stations 1 and 5; as station 1 is the nearest to ground water influx outlet point at the north of the lagoon, whereas station 5 locates at the south of the lagoon and the nearest to the open sea water. High nitrate concentrations were recorded at station 1 over the four seasons 37.08-53.12 g/l, while other stations recorded lower values 0.24-7.27 g/l. High levels of nitrite were recorded ranged from 0.35-15.24 g/l during the period of the study. Ammonia levels were significantly higher at the northern inlet of the lagoon than at the southern outlet 0.37-12.73 g/l. Station 1 sustained high phosphate and silicate concentrations over the four seasons, while other stations recorded lower values. In general, the northern part of the lagoon is influenced by the effluent discharge point receiving groundwater mixed with sewage.