Abstract
Assessing the environmental and climatic impacts in the Nile Basin is imperative for appropriate decision and policy making on national and regional levels. Tracer techniques provide basic spatio-temporal tools for quantifying ongoing and past, and for predicting future, environmental and climatic impacts in whole Nile Basin. These tools allow the sustainable use of the natural resources through developing appropriate large-scale and long-term management and planning strategies. Radiotracers, for example, have diverse properties, unique sources and cycles in the environment. They provide powerful approaches to understand the behaviour of atmospheric processes, and the role of dry and wet-deposition on transfer of matter from the atmosphere to the earth’s surface. They are, also, useful for assessing the present status and evolution, as well as for quantifying the functioning and metabolism, in complex aquatic and land-water systems through appropriate definition of the spatio-temporal scales forcing their interactions with the environment and climate. They yield rich data on sources, pathways and flow-rates of matter (e.g. nutrients and pollutants) within and between landscape units and at the critical boundaries of the hydrosphere with the lithosphere, ecosphere and the atmosphere. Mitigation and adaptation strategies for coupled environment-climate policies require records and observations supported by model and forecasting infra-structures that can simulate the impacts of coupled environment-climate changes both on local and landscape scales. Impacts of global warming are not straightforward to predict unless reasonable scales can be used to compile and collate the diverse climatic and environmental data. Coordinated studies and observations of complex river-, lake-catchment, land-water and delta-coastal systems can provide a wide-range of information on human and climate impacts through using radiotracers as common time and space indicators for assessing the flow of matter on earth’s surface. In this context, the Nile Basin can serve as a model for coupled environment-climate impact studies in complex aquatic systems where sustainable management policies, e.g. use of natural resources, protection and rehabilitation, are needed.
TopIntroduction
The quality of life on the earth depends on a continuous and dynamic flow of matter in its aquatic and ecological systems. Understanding the functioning and metabolism in these systems, in relation to space and time, depends to large extent on understanding the flow of matter in these systems: what are the important flows, how large and how quick? Which factors and processes regulate their dynamics, e.g. where, when and why these flows occur? This knowledge gives the necessary background to understand the evolution of aquatic and ecological systems and to forecast how these systems would respond to various changes in pollution, waste and climate.
An effective method to gain knowledge on these flows is to use radioactive tracers “radiotracers”. Through their property to decay in regular manner they can be used as ”clocks”. Because of this and their dynamic flow and transportation pattern in the environment, studies of radiotracers can mark not only the dispersion of different compounds in space but also in time. The diversity of radiotracers in the environment, in terms of their origin (stratosphere, troposphere, hydrosphere), chemical (reactions under different conditions) and physical (half-lives, decay rates and modes) identities, allows to study different transport and accumulation processes influencing the cycling of nutrients and pollutants on the earth’s surface especially what regards assessing the modern impacts of humans on nature.