Concentrations of dissolved organic matter (DOM) in lakes are often an order of magnitude greater than concentrations of particulate organic matter; nevertheless, the biogeochemical analysis of DOM is described in only a few textbooks on limnology (most thoroughly by Wetzel). The orgins of dissolved organic substances are largely photosynthetic; DOM is either autochthonously synthesized by littoral and pelagic flora through secretions and autolysis of cellular contents, or allochthonously generated in terrestrial systems of the drainage basin, composing largely of humic substances refractory to rapid microbial degradation. The role of DOM in lacustrine ecosystems, as energy source and system regulator, however, is still poorly known. The aim of this book is: (1) to present state-of-the-art reviews of the role of dissolved autochthonous and allochthonous organic matter in pelagial and littoral zones; and (2) to focus attention on poorly understood but critical topics and hence to provide direction for future research activity.

Limnology is increasingly concerned with water supply and the relation of man to aquatic environments. Without the continued availability of pure water, all progress in technology and other fields of human life will be to no avail. The global problems concerning clear water are already extremely pressing. More limnology knowledge is needed to solve these problems. The responsibility of man to save water and to take more intensive care of the environment is raised in many of the papers, in this book. This emphasizes the necessary and unquestionable relevance of limnology to human society. Too often the abuse of water usage reflects the neglect of scientific results. Limnologists have a responsibility to ensure that administrators understand what is going on. The coverage of the book is wide, including papers on microbiology to engineering sciences. The biology of waters is handled at both species and ecosystem levels. The geographical distribution of topics ranges from the tropics to northern temperate areas. In fact, limnology is increasingly becoming a science which is, rightly, relevant to everyday life, not just an academic subject.

Successful management of agricultural landscapes depends on the recognition of the relationships between the processes and the structures that maintain the system. The rapidly growing science of Landscape Ecology quantifies the ways these ecosystems interact and establishes a link between the activities in one region and repercussions in another. A

As human populations expand and have increasing access to technol ogy, two general environmental concerns have arisen. First, human pop ulations are having increasing impact on the earth system, such that we are altering the biospheric carbon pools, basic processes of elemental cycling and the climate system of the earth. Because of time lags and feedbacks, these processes are not easily reversed. These alterations are occurring now more rapidly than at any time in the last several million years. Secondly, human activities are causing changes in the earth's biota that lead to species extinctions at a rate and magnitude rivaling those of past geologic extinction events. Although environmental change is potentially reversible at some time scales, the loss of species is irrevo cable. Changes in diversity at other scales are also cause for concern. Habitat fragmentation and declines in population sizes alter genetic di versity. Loss or introduction of new functional groups, such as nitro gen fixers or rodents onto islands can strongly alter ecosystem processes. Changes in landscape diversity through habitat modification and frag mentation alter the nature of processes within and among vegetation patches. Although both ecological changes altering the earth system and the loss of biotic diversity have been major sources of concern in recent years, these concerns have been largely independent, with little concern for the environmental causes the ecosystem consequences of changes in biodiversity. These two processes are clearly interrelated. Changes in ecological systems cause changes in diversity.

Photoinduced processes, caused by natural sunlight, are key functions for sustaining all living organisms through production and transformation of organic matter (OM) in the biosphere. Production of hydrogen peroxide (H2O2) from OM is a primary step of photoinduced processes, because H2O2 acts as strong reductant and oxidant. It is potentially important in many aquatic reactions, also in association with photosynthesis. Allochthonous and autochthonous dissolved organic matter (DOM) can be involved into several photoinduced or biological processes. DOM subsequently undergoes several physical, chemical, photoinduced and biological processes, which can be affected by global warming. This book is uniquely structured to overview some vital issues, such as: DOM; H2O2 and ROOH; HO•; Degradation of DOM; CDOM, FDOM; Photosynthesis; Chlorophyll; Metal complexation, and Global warming, as well as their mutual interrelationships, based on updated scientific results.

Continuing concern about water supply and quality, ecosystem sustainability and restoration demands that the modern approach to the management of lakes and reservoirs should be based on a sound understanding of the application of the scientific and ecological principles that underlie freshwater processes. The Lakes Handbook provides an up-to-date overview of the application of ecologically sound approaches, methods and tools using experience gained around the world for an understanding of lakes and their management. Volume one of the Handbook addresses the physical and biological aspects of lakes pertinent to lake management, emphasising those aspects particularly relevant to large, still bodies of water. Volume two then considers lake management, with particular emphasis on sustainability, restoration and rehabilitation. This handbook will be invaluable to ecologists, environmental scientists, physical geographers and hydrologists involved in limnological research, as well as advanced undergraduate and graduate students looking for authoritative reviews of the key areas of limnological study. Brings together basic science and management issues. International coverage and international authors. Reviews management issues at a level suitable for the non-expert.