The results of a preliminary organic budget for a small (1.13 h) dystrophic lake in Maritime Canada are presented. Wood's Pond is moderately autotrophically productive (395 mg C m-2 day-'). Allochthonous inputs overwhelmed autochthonous production by an approximate ratio of 9.7:1. Seepage through the surrounding Sphagnum mosses accounted for 89.9% of all organic carbon entering the lake while fluvial transport was responsible for over 90% of losses. The yearly balance was a net loss of approximately 1 820 kg C. The marked dominance of allochthonous inputs over autochthonous production obviously influences the physico-chemical limnology of Wood's Pond but it does not necessarily follow that this system is heterotrophic. The yearly autotrophic production, approximately 1466 kg C, essentially balances an annual community respiration and insect emergence of 1 481 kg C. This suggests that, at least in theory, the biological functioning of this dystrophic lake system could be driven almost entirely by autotrophic production.

No abstract

Diffusion of radon and thoron from the Ilunar surface provides a mechanism for production of a radioactive surface layer on the moon. If the radon and thoron flux from the lunar surface is equal to that measured at the earth's surface, the equilibrium activity of this surface layet is estimated as approximately 1 microcurie per square meter, due to radon and its decay products. This activity consists of alpha particles and gamnmna rays at well-defined energies and of beta rays.

An examination of the decay scheme of Br87, Figure 1, [Evans, 1955], shows the potential existence of a relatively long‐lived source of high‐energy trapped radiation following a high‐altitude nuclear detonation. It is seen that ∼14% of the decays of Br87 are accompanied by the emission of 5.4‐Mev γ rays, while 30% of the decays produce 8 Mev β's. Since the half‐life of Br87 is 55.6 sec, this isotope is a source of high‐energy β's and γ's long after all the other high‐energy β decays have essentially terminated. A survey of the tabulated properties of fission debris products [Katcoff, 1960] indicates that (with one exception discussed below) Br87 is unique in producing such high‐energy radiation with such a long half‐life.