Ozone in the stratosphere is vital to life on Earth. Yet it is chemically unstable and is susceptible to catalytic destruction from a long list of chemical substances, including NOX, HOX, CIOX, and metal oxides. In the stratosphere, these catalysts can be very active in ozone destruction, even when present at only one part of catalyst per 10,000 of ozone.

Pollutants can reach the stratosphere in two ways: (1) by direct injection, as from supersonic transports, military aircraft, rockets, or nuclear bombs, and (2) by indirect injection from the troposphere, which may occur for inert, water-insoluble substances that will eventually work their way up into the stratosphere.

The mass of catalysts sufficient to destroy stratospheric ozone at a significant, world-wide rate is less than the mass of the annual waste products from several industrial operations. In particular, the mass of nitrogen oxides from the exhausts of 500 supersonic transports is far above the threshold for significant catalytic destruction of ozone. This could have profound effects on the working and very maintenance of the biosphere.

Even if, as many of us believe, ‘there is time to avoid the abyss’ of non-survival, there is no time for complacency. Rather is there need for eternal vigilance, scientific monitoring, international legal and other enlightened controls, and often very costly action. For Man is inexorably changing the world, though often insidiously and quite unintentionally. Already he has the knowledge and wherewithal to control his numbers, effects, and very destiny, maintaining the biosphere for himself and to some extent for Nature; but has he the collective wisdom? And what are the limits of his folly? It might be thought that many of our chosen items touched on above are either local or not concerned with the environment as a whole, and hence would not constitute real ecodisasters; but when we look just a little ‘below the surface’, we realize that they could engender in the long run quite disastrous effects on the habitat and life support system of Man which, with his present all-too-heavy impress, could mean the far wider environment of Nature and even the entire biosphere. Meanwhile Man's objective in this age of ecological enlightenment should surely be to maintain optimum diversity in the biosphere—with due emphasis on the ‘optimum’ having regard to the direct needs of Nature as well as of himself.

With Man now the unquestioned superdominant of the world, yet continuing to increase his numbers to the extent of projected doubling in 30–40 years and doubling again thereafter, there are thrust upon us an ever-increasing number and burden of conceivable ecodisasters, many of which we have touched on above. Others can already be foreseen and yet others will doubtless emerge. None seems inevitable in itself, at least in widespread magnitude, and few appear to be at all likely; but still something has got to happen to check the projected mounting demomass, and it seems reasonable to expect it to be one or more of cur listed conceivabilities. Which this may turn out to be, presumably sparking otheis and altogether changing the world even more precipitously than has been the case of late, we can only conjecture.

Soils from the Sudbury region, Canada, which have been contaminated by the heavy metals nickel, copper, cobalt, and iron, from airborne smelter emissions, have been assayed for their toxicity to seedling growth. The extent of radicle elongation in bathing solutions of soil-water extracts has been used as a bioassay index of soil toxicity. The root growth of four species was reduced in extracts of soils which had been collected up to a distance of 49.8 km from the Coniston smelter. Inhibition was greatest in surface soils. Water extracts had metal concentrations of up to 142 ppm Ni, 59.5 ppm Cu, and 4.6 ppm Co. In addition, aluminium occurred in water extracts at 50.6 ppm at 0.8 km from the smelter, and up to 98.9 ppm somewhat farther away, even though it was not smelted in the region.

All of the four metals nickel, copper, cobalt, and aluminium, were shown to be markedly inhibitory to seedling growth at concentrations below 5 ppm. In addition, all of the metals tested were concentrated markedly in the seedlings, expecially in their roots. The concentration factor was often 50- to 100-fold that of the bathing solution. Nickel appears to be the greatest single heavy-metal problem with which the vegetation has to contend. Even in the event that the major emissions of sulphur dioxide in the area be controlled, the concentrations of the toxic heavy metals nickel and copper already existing in the soils over many square kilometres present severe problems for seedling establishment and, consequently, revegetation.

Soil, moss, and conifer twig and needle, samples were collected along an urban-suburdan transect in Connecticut. All samples were analyzed for mercury content. In general, both the mosses and tree tissues contained higher concentrations of mercury than did the soil. Except for the plant samples collected at the origin of the transect adjacent to an electric generating facility, where the mercury in a moss exceeded that in a Juniperus virginiana tree, the floral components that were sampled proved comparable. Moss sampling would probably give the more reliable indication of urban-industrial mercury contamination.

In order to facilitate the work of those who are faced with the difficult task of assigning priorities and guiding conservation action on a global scale, it is important that those countries which have jurisdiction over coastal areas start collecting, evaluating, and disseminating, data on the ecological status of their coastal zones. Only with such a data-base can the appropriate authorities effectively further the concept of conservation and sound management of marine resources. To these ends, also, the existing marine parks and equivalent reserves should be evaluated with special reference to the extent to which they provide adequate protection for representative examples of the ecosystems of the area, and to determine the need for additional areas to be protected.

As part of ongoing marine conservation programmes, IUCN/WWF is giving high priority to the identification of critical marine habitats either for the purpose of setting them aside as protected areas because of their fragility or high productivity, or for their research, education, or aesthetic, values. In cases where a ‘park’ is not the best solution to protect an area from pollution and other disturbances, IUCN/WWF, in cooperation with other organizations—international or national—is trying to help to influence the governmental authorities concerned to find the best possible solution to the problem, whether it concerns over-fishing, using wrong fishing methods (e.g. dynamiting), or is a matter of providing guidance to the authorities concerned to achieve a rational utilization programme of coastal marine resources. Such utilization is particularly important in those parts of the tropics where marine renewable resources play a vital part in the economy of tropical human populations, but where the native fishing cannot continue to supply yields that are sufficient to meet the (usually ever-increasing) demand.

Aquaculture, like any other industry, has the potential to generate pollutants for which the aquaculturist may be held legally responsible. Some of the pollutants created by aquaculture operations include both organic materials originating from excess primary production or inefficient supplemental feeding and toxic compounds such as herbicides, pesticides, and fish poisons. It is possible to utilize excess organic effluents for beneficial purposes such as culturing additional algal and animal species.

Construction of aquaculture facilities can result in physical alteration of the environment—including changes in circulation patterns, increased sedimentation, interference with freshwater input to the estuary, and direct destruction of productive areas. Intensive raft-culture may interfere with natural estuarine production.

Finally, the potentially serious threat from wide spread dissemination of culture species is discussed. Possible problems include introduction of pathogens and all of the ecological problems that are commonly associated with introduced species.