Estuary is an area with very complicated characteristics, which is mainly affected by tidal dynamics. The salinity of a tidal river is influenced by tidal characteristics where fresh water meets salty water and thus causing the complexity. The Love River in Kaohsiung, Taiwan, has been chosen as an study area for the researches describing in this thesis work. The four sampling stations cover the tidal zone of the Love River. Through frequent sampling, which corresponds to spring tides, neap tides and even during complete tidal cycles, the water quality and the variations of particle circulation in estuary area can be comprehended better. The distributions of the nutrients in the river are different during spring tides and neap tides. Nitrite and nitrate are mainly come from the upriver or generated by the nitrification within the river. In addition, the results from the whole tidal cycle experiments show that high flow rate occurs at the bottom during the period of turning tides, which caused higher SPM concentrations in the bottom layer. This is mainly due to the accumulated agitations at the river bottom were resuspended by the strong currents. Analytical results from a Pearson product-moment correlation has shown that the SPM concentrations in the bottom water partly come from the resuspension processes of bottom sediments. Nutrients accumulated in the bottom sediments were released into the water column by the SPM resuspensions. The result of PCA shows that the changes of tides affect the distribution of salinity has a strong negative correlation with turbidity and SPM. It also shows that tides not only have a quite obvious influence on suspended particle matters but also dominate the distribution of suspended particle matters through out the Love River.

The major goal of this research is the development of a competitive ligand equilibration-solvent solvent extraction (CLE-SSE) method to determine organically complexed mercury species in estuarine water. The method was applied to estuarine surface waters of Galveston Bay and the water column of Offatts Bayou. Thermodynamic equilibrium modeling estimated organically complexed mercury species in estuarine water using the conditional stability constants of mercury-organic complexes and the concentrations of organic ligands determined by CLE-SSE. Two competing ligands, chloride and thiosalicylic acid (TSA), were used for CLE-SSE. Chloride ion competition determined conditional stability constants for 1 : 1 mercury-ligand complexes ranging from ~1023 to ~1024 with concentrations of organic ligands at low nM levels. TSA competition determined stronger mercury-binding ligands by manipulating the TSA concentration such that a higher binding strength was achieved than that for the mercury-chloride complex. TSA competition determined conditional stability constants for 1 : 1 mercury-ligand complexes ranging from ~1027 to ~1029, with ligand concentrations ranging from 10 to 100 pM. Mercury-organic binding strengths in these ranges are consistent with bidentate mercury complexation by low molecular weight organic thiols. A linear relationship was observed between log stability constants for the mercury-ligand complex and log ligand concentrations, supporting the hypothesis that there is a continuum of mercury binding site strengths associated with dissolved organic matter. In Galveston Bay, organically complexed mercury accounted for > 95 % of the total dissolved mercury in surface water. Organic complexation of mercury coupled with mercury dissolution from particulate phases controls the filter-passing mercury distribution in surface waters of Galveston Bay. The estuarine distributional features of mercury-complexing organic ligands were similar to those of glutathione, supporting mercury complexation by a thiol binding group. In Offatts Bayou, a seasonally anoxic bayou on Galveston Bay, thermodynamic equilibrium modeling suggests that the speciation of dissolved mercury in anoxic systems is dominated by sulfide complexation rather than organic complexation.

In the field, a 12-month survey was conducted at 6 stations spanning a wide salinity range in the Forth estuary, to investigate the influence of geographical, seasonal, tidal and physical environmental variables on community structure. Pump samples, in two net fractions (69 urn and 250 um) were collected on spring and neap tides, at high and low water over 9 complete or partial lunar cycles. The use of two concentric nets of differing mesh size extended the size range of specimens caught, and permitted the observation and enumeration of small plankters such as rotifers, copepod nauplii and early polychaete larvae. In early 1982, a clear temporal succession of rotifers> freshwater crustacea> Haranzelleria larvae> Eurytemora was observed. The data acquired on field distribution and abundance were analysed in a variety of ways. The most effective approach was found to be a combination of polythetic, divisive classfication (Twinspan) of sepcies data, followed by Multiple Discriminant Analysis (MDA) of the classification using geographical, seasonal, tidal and environmental data as the discriminating variables. The effects of geographical, seasonal and tidal variation were removed by analysing subsets of the data restricted to one state of a variable at a time; comparison of these restricted analyses with those performed on larger data sets revealed, however, that the relative influence of variables on community structure could be readily discerned even when all variables were considered together. Salinity and geographical position of station were clearly the dominant factors in explaining the species associations defined by classification analysis; organic suspended particulate material was closely associated with these, and temperature also but to a lesser degree. The influences of season and primary production were linked, and were orthogonal to the influence of the dominant variables. Classification analysis identified three main assemblages: the freshwater community; a low-salinity group comprising Eurytemora affinis and Neomysis integer; A neritic assemblage dominated by Acartia spp., Pseudocalanus and Oithona but also including Temora, Centropages and meroplanktonic larvae. Pseudocalanus and Oithona were more persistent than the other neritic taxa, and were more often found in samples of lower salinity and in the autumn and winter. Predation and development rate are two biological factors which directly influence the abundance and distribution of individual taxa. In the laboratory, studies were conducted a) on the rate of predation of Neomysis on Eurytemora and b) the effects of temperature and food availability on the development rate of Eurytemora. Predation rates of adult mysids on adult Eurytemora were estimated to range up to 170 prey/day at 500 prey/litre, and the functional response was adequately modelled by a Type II curve. It was experimentally , demonstrated that predation rates were not reduced in the dark or in the presence of detritus, and it is inferred from this that Neomysis relies on random foraging rather than on visual predation. Estimated predation rates were sufficiently high to suggest that Neomysis predation may, at some times of the year, have a significant effect on Eurytemora population size. Development rates in Eurytemora were not affected by food level, but were quantitatively related to temperature. Development was approximately isochronal, but the duration of the second naupliar instar was consistently longer than that of other instars, especially at lower temperatures. Total estimated development times ranged from 39 days at 8 deg.C to 15.25 days at 20 deg.C, with the effect of temperature being more marked at low temperatures than at high temperatures. The results of the development study were applied to field observations of instar body lengths, in order to estimate daily length increment for 9 dates in 1982. Field observations had indicated that, in contrast to many other studies, body size did not bear a simple inverse relationship to water temperature; whilst the smallest animals were observed during the spring bloom .and midsummer, the largest specimens were collected in September when water temperatures were still high. Highest growth rates were estimated for August (small animals) and September (large animals) ; winter animals, although similar in size to September specimens, had low estimated growth rates. The large size of specimens encountered in September suggests, when considered in conjunction with the low abundance at that time, that a switch may have occurred from investment in reproduction to an investment in somatic growth.

No description available.

No description available.

The Patos Lagoon, the largest choked coastal lagoon in the world, is a typical centre of population, commerce, industry and recreation, and consequently it is also a site for disposal of industrial, agricultural and municipal wastes. Important questions concerning beneficial uses of and potential changes to the lagoon and its estuary are left unanswered without a good understanding of hydrodynamic processes. The current study involves the choice, calibration and application of a numerical model which can be used in future hydrodynamic, sediment transport and water quality studies in the area. The two- and three-dimensional modes of the TELEMAC System were chosen to study the hydrodynamics of the Patos Lagoon. In order to calibrate the TELEMAC-2D model for the lagoon, measurements of salinity, current speed and direction, water elevation and wind speed and direction were carried out simultaneously at three stations in the estuarine area during three days. The model validation was carried out against an independent data set from the 1998 El Nino event. Several two-dimensional simulations were carried out to investigate the main processes controlling the Patos Lagoon hydrodynamics. The model was forced with prescribed river inflow at the top of the lagoon, wind stress at the surface and water elevation at the ocean boundary. The barotropic pressure gradients established between the lagoon and the coastal area as a result of local and remote wind combined with the freshwater discharge, proved to be the main forces controlling the lagoon subtidal circulation, as well as the exchanges between the lagoon and the coast. The local wind dominates the lagoon circulation through the set-up/set-down mechanism of oscillation, whereas the non-local wind drives the circulation in the lower estuary. The entrance channel acts as a filter and strongly reduces tidal and subtidal oscillations generated offshore. Three-dimensional simulations proved to be essential. Studies of the processes involved in the estuarine transverse circulation showed that the wind drives the lateral flow in the shallow areas, whereas in the channel it depends on lateral pressure gradients and channel curvature and geometry. Insights on the estuarine baroclinic circulation indicate the barotropic forces as the main mechanism controlling salt water penetration and salinity structure in the estuary. This study produced valuable information into the forces controlling the circulation of the Patos Lagoon and its estuary. Important issues regarding the capabilities of the TELEMAC System twoand three-dimensional modules were explored, producing a valuable tool for further hydrodynamic and sediment transport numerical modelling experiments.

The two aims of the project involved: 1. Devising a system for prediction o f areas of bathymetric change within the Fal estuary 2. Formulating and evaluating a method for interpolating single beam acoustic bathymetry to avoid artefacts o f interpolation. In order to address these aims, sources of bathymetric data for the Fal estuary were identified as Truro Harbour Office, Cornwall County Council and the Environment Agency. The data collected from these sources included red wavelength Lidar, aerial photography and single beam acoustic bathymetry from a number of different years. These data were input into a Geographic Information System (GIS) and assessed for suitability for the purposes o f data comparison and hence assessment of temporal trends in bathymetry within the estuary Problems encountered during mterpolation of the acoustic bathymetry resulted in the later aim of the project, to formulate an interpolation system suitable for interpolation of the single beam, bathymetric data in a realistic way, avoiding serious artefacts of interpolation. This aim was met, successfully, through the following processes: 1. An interpolation system was developed, using polygonal zones, bounded by channels and coastlines, to prevent interpolation across these boundaries. This system, based on Inverse Distance Weighting (IDW) interpolation, was referred to as Zoned Inverse Distance Weighting (ZIDW). 2. ZIDW was found, by visual inspection, to eliminate the interpolation artefacts described above. 3. The processes of identification of sounding lines and charmels, and the allocation of soundings and output grid cells to polygons, were successfully automated to allow ZIDW to be applied to large and multiple data sets. Manual intervention was maintained for processes performed most successfully by the human brain to optimise the results o f ZIDW. 4. To formalise the theory of ZIDW it was applied to a range of idealised, mathematically defined chaimels. For simple straight and regular curved, mathematical channels interpolation by the standard TIN method was found to perform as well as ZIDW. 5. Investigation of sinusoidal channels within a rectangular estuary, however, revealed that the TIN method begins to produce serious interpolation artefacts where sounding lines are not parallel to the centre lines o f channels and ridges. Hence, overall ZIDW was determined mathematically to represent the optimum method o f interpolation for single beam, bathymelric data. 6. Finally, ZIDW was refined, using data from the Humber and Gironde estuaries, to achieve universal applicability for interpolation of single beam, echo soimding data from any estuary. 7. The refinements involved allowance for non-continuous, flood and ebb type charmels; consideration of the effects of the scale of the estuary; smoothing of the channels using cubic splines; interpolation using a 'smart' ellipse and the option to reconstruct sounding lines from data that had previously been re-ordered.

No description available.

An oxygen-deficient (12.8 microM dissolved oxygen and oxygen saturation 5.0-7.4% in the water of the deep hole) isolated water system in the deep hole of the Yarra River estuary was investigated to discover the relationship between iodate and iodide. The iodate concentration in the water of the deep hole was very low (0.039 to 0.062 microM at bottom water, salinity from 26.8-30.0 Practical Salinity Scale, 1978), because iodate reduced to iodide in the water by reducing agents (S2-, Fe2+ and Mn2+) diffused from the sediment of the deep hole. / The concentrations of iodine species in the sediment pore water and suspended material in the water of the deep hole were determined to investigate iodine cycling in the deep hole. The iodine flux from sediment into overlying water in the deep hole was 15.6 micromol/m^2.day. The concentration of total inorganic iodine (iodate+iodide) in the dry suspended material from the water of the deep hole was 0.117 micro mol/g. The water residence time in the deep hole was studied. In winter especially, the seawater of high density may intrude into the deep hole with the highest tides. The seawater remains trapped in the deep hole below the halocline, which allows the development of oxygen-deficient conditions. / It was found that in the deep hole the iodide concentration increase resulted from sediment diffusion (36%), iodate reduction (27%) and release from suspended material (37%) during the water residence time in the water of the deep hole. The iodine cycling in the deep hole was: iodate in the water reduced to iodide by reducing agents diffused from sediment; suspended material containing soluble or particular iodine may release iodide and also trap iodate and iodide from water during precipitation; iodate in the sediment reduced to iodide and iodide diffused from sediment into overlying water. Iodine is accumulated in the isolated water in the deep hole and might be moved out at the next water exchange.

Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2009.