Contemporary Issues in Science and Society – serie

Chemical pesticides continue as a point of major controversy in our society. Increasingly stringent regulatory actions on the part of state and federal agencies, exemplified by the RPAR (Rebuttable Presump­ tion Against Registration) program of the Environmental Protection Agency, are supported by environmental groups and are generally op­ posed or viewed with skepticism by agriculturalists. The energy crisis invokes other questions on benefits of pesticides versus nonchemical controls and effects on labor utilization. As DDT and other persistent pesticides have been phased out, the more labile, short-lived chemicals have filled the voids in pest management systems; and effects on nontarget species appear to have declined in recent years as the shift occurred. However, nagging ques­ tions of the hazard to man and other nontarget species from long-term, low-level exposure to pesticides are frequently raised; and recent suggestions that certain well-known and long-used chemicals cause cancer, increase sterility, and initiate or augment other deleterious effects in test animals have instilled a sense of caution and raised con­ cern about the continued availability of some pesticides previously considered safe. So the facade of concern and confusion continues. This book is an outgrowth of a symposium at the meeting of the American Association for the Advancement of Science in February, 1978. An introduction has been added, and some of the papers have been modified since presentation.

The intense current interest in the development of solar energy as a viable energy alternative comes as no surprise in view of the widespread awareness of impending world-wide energy shortages. After all, the magnitude of energy available from the sun is impressive, its diffuseness and intermittent nature notwithstanding. The fact that, as a source, it represents a constant and inex­ haustible supply of energy is alluring. The fact that most solar application schemes are nonpolluting in nature is an attractive bonus. In spite of these impressive attributes, research and development in the area of solar energy is in its infancy, owing largely to the prior lack of any need to exploit such diffuse sources. Indeed efforts in this area have traditionally been within the province of solid-state physics and engineering. The problems associated with efficient light harvesting and storage, however, are not simply technological ones. Effec­ tive solutions to these problems appear to lie beyond the current forefront of the chemical sciences. Consequently input fr9m scientists previously engaged in fundamental chemistry has begun to emerge. Thus many of the contributions in this volume represent input from research groups with a relatively short history of involvement in solar energy. On the other hand, the long-standing and perceptive commitment of Professor Melvin Calvin to research involving solar energy represents the other extreme. This volume covers a variety of approaches to the problem of efficiently converting and storing solar energy.

Estuaries are eternally enriched. Their positions at the foot of watersheds and their convenience as receiving bodies for the wastes of cites, towns and farms results in continuous addition of nutrients - those elements and compounds which are essential for organic production. Such materials must be added to these complex bodies of water to sustain production, since there is a net loss of water and its contents to the oceans. Enrichment from land and the ocean and the subsequent cycling of the original chemicals or their derivatives contribute to the extraordinarily high values of estuaries for human purposes. Many estuaries are able to assimilate large quantities of nutrients despite the great fluctuations which occur with variations in the flow from tributaries. The nutrients can be stored, incorporated in standing crops of plants, released, cycled and exported - and the system frequently achieves high production of plants and and animals without creation of any undesirable results of enrichment. Excessive enrichment with the same elements and compounds can, however, be highly detrimental to estuaries and their uses. Coastal cities are usually located on the estuaries which provided a harbor for the- and which now receive partially treated sewage and other wastes from the expanding population and industrial activity. Conversion of woodlands to agricultural use and the extensive application of fertilizers have resulted in the flow of large quantities of nutrients down the hill or slopes and eventually into the estuary.

Explores how the motion and interaction of fresh and salt water determine the salinity within a particular estuary, and thereby the balance of all living and nonliving resources there. This text, based on a conference on estuarine circulation, focuses on the many variations of the two-layered net, or nontidal gravitational pattern, which was first proposed by Dr Donald Pritchard, and pays special attention to the factors that control estuarine transport processes. Estuarine circulation is important because water movement transport marine organisms, sediments, and pollutants. In addition, estuarine circulation affects food chains, as well as the distribution and abundance of organisms that are transported by the currents during larval stages.

Estuaries are eternally enriched. Their positions at the foot of watersheds and their convenience as receiving bodies for the wastes of cites, towns and farms results in continuous addition of nutrients - those elements and compounds which are essential for organic production. Such materials must be added to these complex bodies of water to sustain production, since there is a net loss of water and its contents to the oceans. Enrichment from land and the ocean and the subsequent cycling of the original chemicals or their derivatives contribute to the extraordinarily high values of estuaries for human purposes. Many estuaries are able to assimilate large quantities of nutrients despite the great fluctuations which occur with variations in the flow from tributaries. The nutrients can be stored, incorporated in standing crops of plants, released, cycled and exported - and the system frequently achieves high production of plants and and animals without creation of any undesirable results of enrichment. Excessive enrichment with the same elements and compounds can, however, be highly detrimental to estuaries and their uses. Coastal cities are usually located on the estuaries which provided a harbor for the- and which now receive partially treated sewage and other wastes from the expanding population and industrial activity. Conversion of woodlands to agricultural use and the extensive application of fertilizers have resulted in the flow of large quantities of nutrients down the hill or slopes and eventually into the estuary.

Chemical pesticides continue as a point of major controversy in our society. Increasingly stringent regulatory actions on the part of state and federal agencies, exemplified by the RPAR (Rebuttable Presump­ tion Against Registration) program of the Environmental Protection Agency, are supported by environmental groups and are generally op­ posed or viewed with skepticism by agriculturalists. The energy crisis invokes other questions on benefits of pesticides versus nonchemical controls and effects on labor utilization. As DDT and other persistent pesticides have been phased out, the more labile, short-lived chemicals have filled the voids in pest management systems; and effects on nontarget species appear to have declined in recent years as the shift occurred. However, nagging ques­ tions of the hazard to man and other nontarget species from long-term, low-level exposure to pesticides are frequently raised; and recent suggestions that certain well-known and long-used chemicals cause cancer, increase sterility, and initiate or augment other deleterious effects in test animals have instilled a sense of caution and raised con­ cern about the continued availability of some pesticides previously considered safe. So the facade of concern and confusion continues. This book is an outgrowth of a symposium at the meeting of the American Association for the Advancement of Science in February, 1978. An introduction has been added, and some of the papers have been modified since presentation.

The intense current interest in the development of solar energy as a viable energy alternative comes as no surprise in view of the widespread awareness of impending world-wide energy shortages. After all, the magnitude of energy available from the sun is impressive, its diffuseness and intermittent nature notwithstanding. The fact that, as a source, it represents a constant and inex­ haustible supply of energy is alluring. The fact that most solar application schemes are nonpolluting in nature is an attractive bonus. In spite of these impressive attributes, research and development in the area of solar energy is in its infancy, owing largely to the prior lack of any need to exploit such diffuse sources. Indeed efforts in this area have traditionally been within the province of solid-state physics and engineering. The problems associated with efficient light harvesting and storage, however, are not simply technological ones. Effec­ tive solutions to these problems appear to lie beyond the current forefront of the chemical sciences. Consequently input fr9m scientists previously engaged in fundamental chemistry has begun to emerge. Thus many of the contributions in this volume represent input from research groups with a relatively short history of involvement in solar energy. On the other hand, the long-standing and perceptive commitment of Professor Melvin Calvin to research involving solar energy represents the other extreme. This volume covers a variety of approaches to the problem of efficiently converting and storing solar energy.