Modelling of phosphorus adsorption processes in estuarine and coastal water

• Main Author: Al-Enezi, Eqbal Hussain
• Published: Cardiff University 2011
• Subjects: 551.46
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.585102

This study consists of three parts: (i) Field work and data collection from the Loughor and Severn Estuaries. P adsorption increased with decreasing median sediment size in both estuaries. A positive correlation was found between the P adsorption in sediment and salinity in the Loughor Estuary, whereas a negative correlation was found in the Severn Estuary. Some factors, such as particle grain size, salinity, pH, organic matter, suspended sediment concentration and P concentration were found to control the exchangeable or loosely sorbed P (adsorbed P) in both estuaries. (ii) Laboratory experiments were conducted on P adsorption/desorption on different types on sediment, including Kaolinite, Silica, mud, silt, sand and suspended sediment. P adsorbed to the mud fraction than to the sand fraction. The adsorption coefficient (K_d) and Maximum P adsorption (PS_Max) for the mud fraction were 0.0091/g and 0.39 mg/g for the silt 0.007 l/g and 0.30 mg/g and the sand 0.001 l/g and 0.05 mg/g. (iii) Flume experiments were conducted in the hydraulic laboratory at Cardiff University, U.K. The main findings revealed that the velocity and the P concentrations in the water were important factors controlling the amount of P adsorbed processes on the sediment. The results from the field work and the laboratory experiments were similar to flume channel findings. These findings were used to develop new source term equations and these equations were added to the QUAL2E water quality model to improve the capability of the model to predict the P adsorption processes in a 2D computer model. These new equations were then used to simulate P concentrations in the estuarine environment using DIVAST.