No description available.

No description available.

No description available.

No description available.

This study is concerned with the relationship between two hydrolytic enzyme activities, saccharase and protease and other limnological factors, including bacterial flora, in natural waters of varying degrees of organic pollution. Published methodologies for measuring proteolytic and saccharolytic activities were employed to yield data whose statistical distribution was found to be modelled by a log-normal distribution. Natural activities were correlated with biochemical oxygen demand, suspended solids, viable bacteria, combined nitrogen, dissolved solids, flow and temperature. Regression equations are formulated with biochemical oxygen demand and bacterial numbers either singly or combined explaining most of the variation in enzyme activity. Other contributory factors were suspended solids, flow and temperature. These equations could predict enzyme activity at other sites with acceptable levels of confidence. The best predictive equations for enzyme activities were: log Saccharase = 0.2 log BOD + 0.1 log Suspended solids + 0.8 log Viable count + 0.9 Protease = -469 Temperature + 56708 Flow + 443 BOD - 1.54 Viable count + 6853 Aquatic bacteria producing enzyme activity were isolated from watercourses and identified as belonging to the genera Pseudomonas. Flavobacterium and Flexibacter. When grown in defined media, enzyme production was stimulated by the addition of sucrose or casein to the medium. In the case of one organism casein could act as sole source of carbon and nitrogen. Extracts of cell suspension were shown to have enzyme activities. When investigated these activities had maximum values dependent on pH and temperature. This pH and temperature profile of activity was also demonstrated in samples of river water. Enzyme extracts followed Mlchaelis-Menten reaction kinetics with Michaelis' constants similar to those reported in comparable extracts.

Environmental problems associated with the use of water are inherently complex, involving the interaction of several different systems. Further, there is often limited data on the interaction, because of its location between disciplines. In order to study these problems in a quantitative, policy relevant way, a numerical model is required that integrates the different systems and is tailored to contain the processes important to the interaction. A numerical water resource system model is developed to study the problems associated with the interaction between agriculture and water. The model integrates an econometric model of farmer behaviour with a dynamic model of water flow and solute transport. The Argolid valley in Greece represents an area where severe environmental problems have arisen as a result of the overexploitation of groundwater for agriculture. When applied to the Argolid valley the water resource system model reproduces the evolution of the environmental problems that have arisen. It is then demonstrated that the model can be used to investigate some future scenarios and policy options related to the environmental problems that have developed. The main contribution of this research is to demonstrate that a properly designed numerical model that reproduces the dynamic interaction between human behaviour and the physical environment can enable the exploration of the evolution of environmental problems despite a lack of calibration data. Having achieved this the model can then be used in a policy relevant way to investigate the implications from a range of different, possible policy options.

No description available.

No description available.

A small-scale filed experiment was conducted on a hillslope plot within the Georgia Piedmont, USA, with the aim of elucidating the hydrological processes which generate storm runoff and its chemistry. Intensive hydrometric and chemical sampling enabled the collection of detailed observations of hillslope processes during rainstorms. The passage of water was traced through a one-dimensional profile in the hillslope, where rainfall, throughfall, forest floor soil water, soil water at 15, 40, 50 and 70 cm depths, groundwaters and streamwaters were monitored, either manually or automatically. Chemical samples for each water type were also collected. From analysis of hydrometric data, several hydrological flowpaths were detected that contribute water to storm runoff. Direct channel rainfall is operative in all storms, although its detection is difficult. Overland flow is in operation at some locations on the hillslope, specially in topographic lows. Macropore and mesopore flow occurred and may lead to groundwater displacement. Groundwater ridging also occurred. Each flowpath was found to vary in its operation, according to a series of controls, namely seasonality, antecedent moisture conditions, rainfall magnitude, duration and intensity, and the timing between rainstorms. Conservative tracers (chloride and temperature) were employed to investigate the contribution of 'old' and 'new' water to storm runoff. The variation in chloride concentrations in samples collected either sequentially or manually at each flowpath was monitored throughout storms. Rainfall, comprising 'new' water, was found to exhibit a distinct chloride chemistry. Most samples contained < 20 μeq/l Cl⁻. A similar trend was observed for samples of through fall and forest floor soil water. Groundwaters and matrix soil waters contained two to three times greater chloride concentrations than in the 'new' waters, due to evaporative mechanisms. Hence, 'new' water could be distinguished from 'old' water on the basis of chloride chemistry. Similarly, the temperature profile of 'new' and 'old' waters were significantly different. During the summer, rainfall ('new' water) is warmer than groundwater ('old' water), and during the winter, the reverse is true. Hence, both chloride and temperature were instrumental in distinguishing 'old' from 'new' waters. Direct channel rainfall, overland flow and macropore flow were important flowpaths for the rapid transport of 'new' water through the system during the growing season. Overland flow contributed some 'old' water during the dormant season. Although macropore flow allowed rapid transit of 'new' water to depth, this led to a groundwater displacement mechanism, which ultimately led to the rapid contribution of 'old' water to storm runoff. The combination of hydrometric and tracer data enabled a conceptual hydrological model to be developed of the responses of the hillslope to storm events.

No description available.