Selenium in minute quantities has been shown to be a dietary essential for animal life, and soil-plant-animal relations have been identified in the distribution of the element. In some cases, soils are frankly deficient in selenium—most particularly those derived from igneous rocks, and the deficiency in surface layers may be aggravated by intensive irrigation. Alternatively, soil selenium may exist in a form that is either unavailable to plants or absorbed by them with difficulty. Representative of such a form is the highly insoluble ferric oxide-selenite complex which frequently occurs in high-moisture, acid soils. Uptake of selenium by plants may also be inhibited by presence of interfering substances in the soil, such as sulphur, or it may be enhanced by liming. Analytical surveys have revealed also that considerable variation exists among plant species in their abilities to take up and retain selenium from the soil. Legumes have been consistently implicated as forages conducive to white muscle disease, a selenium-responsive myopathy, and New Zealand observations have shown white clover ( Trifolium repens L.) to contain significantly lower levels of selenium than grasses, and particularly a native grass, browntop ( Agrostis tenuis Sibth.). In addition to the differences in absolute selenium uptake, it has been suggested that some plants, and again legumes are suspect, may contain organic inhibitors of selenium utilization by livestock. Some experiments have investigated the effectiveness of additions of selenium to the soil in overcoming selenium deficiency among farm animals. Protection for 2 yrs has been achieved by this technique; however, the various factors influencing the soil-plant-animal relations of selenium direct caution in its application.

Recognition of zinc deficiency as a problem in man has taken a long time. Although the metal was shown to be essential for the development and the growth of Aspergillus niger in 1869, of plants in 1914, and of animals in 1934, an essential role of zinc in man was considered to be unlikely until recently. Within the past few years, however, investigators have demonstrated, in rapid succession, that zinc deficiency is common in man, that this deficiency is a critical factor in some forms of impaired growth, delayed healing, and chronic disease. The development of systematic zinc therapy for man offers a new approach to the treatment of growth problems, indolent wounds, and other conditions associated with zinc deficiency.

Therapies for environmental element deficiencies and toxic excesses have been only partially perfected for plants, animals, and man, and require much additional study. Chemical and natural fertilizers are frequently applied irrationally to the soil because of incomplete information on (1) nutrient deficiencies and availabilities from the soil; (2) imbalances caused by chemical fallout; (3) translocation mechanisms from soil to plant; and (4) the effect of runoff on water composition. Range-fed domestic and wild animals seem to present more problems than confinement-fed animals because of the lack of quality control of their rations. Apparently, man reflects environmental deficiencies and toxic excesses more than do animals because of man’s longer life, free choice of diet, and poor quality control of food. Leaf and hair analyses provide very useful methods of evaluating regional element imbalances and therapies for these imbalances. Further developments of these therapies will provide more and better food and will serve to correct the large geographical differences in life expectancy in the United States. Any large-scale therapy needs constant re-evaluation and improvement, as is illustrated by current problems with air, water, soil, and foodstuffs.

Abstract The Taconic Foreland Basin formed during the collision between the North American craton and the Ammonoosuc Arc, approaching from the east. Oxygen-depleted conditions in the basin were probably caused by density stratification in the water column due to a locally humid climate, in combination with stagnant conditions in the world ocean. A long-term cyclicity of alternating 500,000 to 1,000,000 year long “anaerobic phases” and “dysaerobic phases” appears to be the result of a combination of variations in the sedimentation rate, climatic conditions, and changes in the world ocean.