The concentrations of trace metals: cadmium, copper, nickel, lead and mercury, in addition to aluminium, iron and manganese were determined in the sediments and pore water (except aluminium) of the Forth estuary. Organic matter (as loss on ignition), total organic carbon (TOe), total organic nitrogen (TON), particle size and redox potential were also determined in the sediments. In addition, chloride, sulphate, conductivity, alkalinity, pH, dissolved organic carbon, phosphate and nitrate were determined in the sediments pore water. Trace metals in the pore water were determined using a modified preconcentration technique and measurements were carried out by graphite furnace. Mercury was measured using the p.s.a mercury specific fluorescence detector. organic matter (TOC & TON) in the sediments were measured using CHNS/O analyzer. Samples were collected at seasonal intervals for a period of 18 months on board the survey vessel "Forth Ranger". Six stations were selected to represent upper, middle and lower estuary. Sediment cores collected at each station were subjected to centrifugation under nitrogen gas atmosphere to separate the pore water after being sectioned at 2.5 cm intervals for a depth of 10 centimetres. Concentrations of trace metals in the Forth estuary varied from station to station and from one season to another. Mean concentrations for sediments were as follows (mg\kg): lead, 56.9; cadmium, 0.22; copper, 38.9; nickel, 33.7 and mercury, 1.86. For pore water, the mean concentraxxi tions (Jlg\l) were as follows: lead, 3.14; cadmium, 1.86; copper, 31.9; nickel, 24.7 and mercury, 0.075. Measurements of sulphates, nitrates, phosphate, conductivity and dissolved organic carbon were used to examine the processes controlling their distributions in the pore water. The results indicated that the distributions of nutrients (phosphate and nitrate) in the upper 10 cm seemed to be controlled by macro-infaunal irrigation activities and their values varied according to the overlying water conditions. The distributions of trace metals in the sediments were found to be controlled by particle size and organic matter both spatially and temporally. Vertical distribution of trace metals in the pore water were found to be controlled by redox potential variations especially for iron and manganese. Concentrations of trace metals (Pb, Hg, Ni, Cd and CU) in the pore water were found to be higher than that in the overlying water. Enrichment factors were limited to 10-50 fold increase. Lead and mercury were 10 fold higher while 50 fold higher were found for nickel, copper and cadmium. Benthic flux calculations showed a significant flux of trace metals both in the summer and winter. However, flux of copper, nickel and lead tended to increase in the summer. Spatially, the lower estuary showed a higher flux of trace metals than the upper and middle reaches of the estuary.

In the design of urban drainage systems, synthetic design storms are commonly used to predict the peak flow rate in sewer systems and such storms are usually based on local intensity-duration frequency curves or design storm profiles. To estimate the quality of storm flow, the UPM Manual (1994) has highlighted the development of detailed and sophisticated simulation models to estimate the pollutographs, that is, the temporal variation in the concentration of pollutants in urban drainage systems. The data requirements of these models are quite onerous, and as a consequences implified models like SIMPOL have been developed. This model predicts the BOD at 1 hour time intervals and is based on the representation of the sewer system by a series of tanks. This approach may be considered satisfactory for the prediction of accumulative pollution over an annual series of events but for the prediction of acute effects, for example, the first foul flush, the temporal variation in the concentration pollutants in sewer flow is required. There is a need therefore to describe the change in pollution over a much smaller time interval than that proposed in SIMPOL and this is particularly so when consideration is given to the comparison of the design and control options which may be proposed, for example, the real time control of storage tanks to retain the first flush of pollutants. The work outlined in this thesis presents an alternate simple methodology to estimate the pollutographs corresponding to a particular storm event. The work is based on the results of the measured pollutographs recorded on the WRc sewer quality archive (1987) from two catchments at Great Harwood and Clayton-le- Moors in the North West of England. The relationships for the shape of the pollutograph were obtained by the direct comparison of the observed pollutographs. The peak TSS concentrations were obtained by a detailed regression analysis of the observed peak TSS concentrations, the antecedent dry weather period and the hydrological parameters of maximum rainfall intensity, average rainfall intensity and storm duration. These parameters were then related to the shape of the pollutograph and the results of this methodology were shown to satisfactorily reproduce results for the catchments considered. For practical applications, the suggested procedure provides a methodology to calibrate the design pollutographs for any catchment from a limited number of monitored storm events and to utilise these together with time series storms to assist in the performancea ssessmenat nd selectiono f alternative design options. The work has the limitation that it is catchment specific but as more information for different catchments becomes available, it may be possible to establish standard pollutographs for application to a wide range of catchment conditions.

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published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

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