Pollution Monitoring Series – serie

The job of the responsible zoologist should be to assess or attempt to predict the consequences of any effluent or other environmental disturbance as objectively as possible, bearing in mind both the needs of conservation and the reasonable demands of man. This book has been written to assist this process of assessment and prediction as far as thermal discharges are concerned. It gives a summary and review of the biological studies which have been carried out in various habitats and in response to a variety of problems related to cooling water usage, particularly on the large scale as in thermal power stations. By discussing and summarizing the hugely variable field studies, the book should help the reader to unravel the complexity of the effects of at least one kind of effluent. It should also be of use in the future planning of industries which use cooling water and for the controlling authorities whose task is to set realistic constraints on these industries.

Trace metals occur as natural constituents of the earth's crust, and are ever present constituents of soils, natural waters and living matter. The biological significance of this disparate assemblage of elements has gradually been uncovered during the twentieth century; the resultant picture is one of ever-increasing complexity. Several of these elements have been demonstrated to be essential to the functions of living organisms, others appear to only interact with living matter in a toxic manner, whilst an ever-decreasing number do not fall conveniently into either category. When the interactions between trace metals and plants are considered, one must take full account of the known chemical properties of each element. Consideration must be given to differences in chemical reactivity, solubility and to interactions with other inorganic and organic molecules. A clear understanding of the basic chemical properties of an element of interest is an essential pre-requisite to any subsequent consideration of its biological significance. Due consideration to basic chemical considerations is a theme which runs through the collection of chapters in both volumes.

The role of the European Community in developing environmental legislation has focused the minds of pollution control agencies and industrialists on the need for, and the evidence to support, water quality standards. This is particularly so for the Dangerous Substances Directive which has led to European standards for cadmium, mercury and lindane. Additionally the United Kingdom has published standards for six other non-ferrous metals. In this book I have sought to review the aquatic toxicity information for these and other metals, not just by the collation of the results of all the published toxicity tests, but by the critical consideration of the test techniques. A surprising proportion of the reported toxicity studies for aquatic organisms are based on unsatisfactory chemical or biological methods. That such weaknesses persist at a time of limited resources for environmental research is disappointing, especially when sound metho­ dologies are extensively documented and widely published. Evaluation of the critically reviewed and vetted data indicates that many of the previously accepted generalisations about the toxicity of metals to aquatic life are invalid: for instance the assumption that salmonid species of fish are more susceptible to these metals than coarse fish, or that increased water hardness decreases toxicity. Too few studies have actually sought to test such hypotheses.

The preface of a book often provides a convenient place in which the author can tender his apologies for any inadequacies and affords him the facility to excuse himself by reminding the reader that his art is long but life, or at least the portion of it in which he has the opportunity for writing books, is short. I, too, am deeply conscious that I have undertaken a task which I could not hope to complete to my own satisfaction but I offer, in self­ defence, the observation that, inadequate though it is, there is no other book extant, so far as I am aware, which provides the information contained herein within the covers of a single volume. Often during the last decade, in discharging my responsibilities for the environmental aspects of the water authority's operations and works, I should have been deeply grateful to have had access to a compendium such as this. The lack of a convenient source of data made me aware of the need which I have attempted to fill and in doing so I have drawn on my experiences of the kinds of problem which are presented to biologists in the water industry. The maxim 'half a loaf is better than none' seems particularly apt in this context.