Laser ablation MC-ICP-MS allows in situ strontium isotope data to be obtained for incrementally formed bioapatites such as enamel with extremely high spatial resolution. Here, we provide a large-scale application of the method comparing the ...Understanding mobility and landscape use is important in reconstructing subsistence behavior, range, and group size, and it may contribute to our understanding of phenomena such as the dynamics of biological and cultural interactions between distinct ...
1. Methods are described for the determination of the phosphorus present in particulate form and of the total phosphorus in a sample of sea water. 2. The distribution of phosphorus present as inorganic phosphate, as dissolved organic compounds, and as particulate matter (detritus and microörganisms) has been determined at all depths throughout the year at a station in the western part of the Gulf of Maine. 3. In late winter over 90 percent of the phosphorus is in inorganic form and three-quarters of the remainder is present as soluble organic compounds. 4. In the spring—February to May, inorganic phosphorus is converted to organic form by photosynthesis in the upper layer of water. Most of this fraction sinks to considerable depths before undergoing decomposition. 5. During the summer—May to November, large quantities of dissolved organic phosphorus appear at all depths, indicating a very considerable transport of inorganic phosphate from deep water to the surface and the sinking of an equivalent amount of phosphorus in particulate form to the depths in which organic compounds are liberated by decomposition. Decomposition appears to take place throughout the water column. 6. During the winter—November to February, the organic phosphorus compounds are converted to inorganic phosphate. This and vertical mixing of preformed phosphate are about equally important in bringing about the equalization of phosphate concentrations throughout the depth of water. 7. A method is described for analyzing quantitatively the factors producing a seasonal change in the distribution of a compound such as phosphorus. It is shown that the vertical transport of material within the water mass demanded by such an analysis may be accounted for reasonably by the hydrographic conditions obtaining. 8. Values of the coefficient of eddy conductivity at several depths are obtained.
The major features of the thermal regime in the peat of a salt marsh at Barnstable, Massachusetts, are described by the theory of heat flow in a homogeneous noncon-vective medium subjected to an annual sinusoidal change in temperature having an amplitude of 12°C at the surface. The thermal diffusivity of the peat is 1.57 × 10−3 cm2 sec−1. Departures, attributed to meteorological effects, consist of a long term trend during the two-year period of observation, which may be approximated by a biennial sinusoidal component of 1°C amplitude, and of somewhat irregular perturbations occurring at intervals of about three months. The average effects attributed to the latter attenuate with depth at the rate expected for a component of one quarter year period. In the deeper layers of peat residuals remain after these components are eliminated from the observed data which are accounted for by the movement of ground water from the upland, a condition evidenced by the low chloride content of the peat at these depths. The mean temperature of the peat increases downward at a rate which indicates, when combined with the thermal diffusivity and volumetric heat capacity, that heat is moving upward through the peat layer at an average rate of 1.58 × 10−6 cal. cm−2 sec−1. This value agrees with previous determinations of the geothermal heat flux. The march of temperature at the marsh surface agrees closely in amplitude and epoch with that of the air over the upland. The mean temperature of the marsh is 0.9° cooler than the air, an effect attributed to evaporation. The effect of spring tides which flood the marsh is examined and it is concluded that the principal effect is to keep the peat moist and thus increase evaporation.
A population of small specimens of the pteropod, Limacina retroversa, appeared in the eastern part of the Gulf of Maine in December, 1933. From collections made during the following 9 months information was obtained showing that the population was a homogeneous one, that its members grew to maximum size in 5 months, declining in numbers as they did so.A second population of small individuals appeared in the Gulf in late spring, originating chiefly from offshore, but possibly in part being offspring of the original population. These were unsuccessful in maintaining their numbers throughout the summer.In addition to the information on the life history of Limacina, the data indicate the rate of drift of the water in its circuit of the Gulf. It supplies also suggestive information on the dispersal of organisms through the lateral mixing of water. It emphasizes the dependence of pelagic organisms upon the current systems of the ocean and the difficulty involved in maintaining a permanent population in any one locality.
Sedimentation has continued in the Maracaibo Basin since the formation of its earliest oil-bearing strata. The present lake is reputed to be one of the most productive waters in the world. Perhaps no more favorable place can be found for examining the conditions presumed to precede the accumulation of organic matter in sedimentary deposits. The lake appears to have been fresh in the recent past. Sea gained access to the basin when the rising sea level drowned its approaches to a present depth of 60 feet. Since then marine sediments have greatly reduced the sill depth. Escaping fresh limits the entrance of sea water, which occurs only during three months of the dry season. The lake contains about one part in thirty of sea water, uniformly distributed by an active wind-driven circulation. In the deeper basin, with depths of 100 feet, the salt content is substantially higher. The oxygen content of this water is reduced and over a large area of bottom is anaerobic. The fauna of the lake on superficial observation is limited in variety and numbers. Marine forms are restricted to species adapted to life at very low salinities. The significant bulk of organic matter is produced by fresh-water species of planktonic algae. These at times produce prominent surface blooms. The potential fertility of the lake is revealed by its phosphorous content. The total phosphorous is about 1.4 microgram atoms per liter in the mixed layers above the This is more than commonly found in surface waters of the sea, but is less than that of the deep of the Pacific and Indian Oceans. The phosphorus, and presumably other nutrients, are derived from land drainage and are accumulated in the lake by evaporation and by the sinking of organisms into the deep water. One third of the phosphorus is present in inorganic form available for plant nutrition. Consequently, growth is not limited by its availability in the photic zone. In the water the phosphorus content is manifoldly increased by the sinking of organisms. The oxygen available is insufficient to oxidize this accumulation, and conditions unusually favorable for the entrapment of organic matter in sediments result. Sedimentation is active in the lake, particularly in the southwest quarter, where the Catatumbo River is building an extensive delta. Its discolors the lake for a great distance along the shore. The lake bottom consists of soft blue mud which, in the anaerobic region, is black for several inches below the surface and smells strongly of H2S. The mud is sufficiently unconsolidated to permit a test pile to sink 30 feet under its own weight. It is concluded that Lake Maracaibo is an unusually favorable place to study the processes which lead to the entrapment and the subsequent transformation of organic matter in sediments. Petroleum in its natural occurrence is closely associated with marine or semi-marine nearshore sediments. The relation is practically universal and has persisted since Cambrian time, very probably without material alteration. The study of the depositional zones of present-day seas and oceans therefore appears essential to an understanding of oil occurrence, particularly in its initial stages. Eugene Stebinger (1950).
The construction and operation of a corer capable of recovering uncontaminated and uncompressed samples of peat and other soft sediments from precisely predetermined depths is described.
The tides of coastal embayments derive their energy from the ocean tides rather than from the direct action of lunar and solar gravitational forces. They are considered to be part of co-oscilating systems in which the period is determined by the tide in the outer sea, while the detailed character of the motion depends on the size and form of the enclosed basin (Defant, 1925; Doodson and Warburg, 1941). In narrow basins of simple form in which the influence of the earth's rotation is small, the motions resemble standing waves. Ideally, such waves are characterized by the simultaneous rise and fall of level on either side of a nodal line at which no change in elevation takes place. The elevation at high water increases with distance from the nodal line and slack water coincides with high and low water. The properties of tides due to standing waves may be deduced by assuming the motion to result from a primary progressive wave moving up the channel which undergoes complete reflection at a barrier. Mathematically, this situation may be treated as the interference of two identical progressive waves moving in opposite directions and so related that both waves are in phase at the barrier. This treatment of standing waves assumes the presence of total reflection, the absence of damping and the absence of effects of the earth's rotation. Since these conditions are not realized in natural tidal basins, the standing wave concept leads to oversimplification. In coastal embayments the most striking departure from the expectations of the standing wave concept is the discrepancy between times of high water and slack water, which may be great near the mouths of the larger bays and sounds. High water does not occur simultaneously within such enclosures but is earlier near the sea. Commonly, the nodal line is represented merely by a region in which the tidal range is small. These are effects which can be explained if damping of the primary and reflected waves by frictional or other effects is taken into account. According to these concepts, the problem of tidal behavior in embayments is to determine numerically the properties of the primary and reflected waves so as to account for the observed relations of amplitude and stream velocity of the actual tide and to correlate these numerical properties with the geographical form of the embayment. In the present paper an attempt is made to treat the tidal behavior in such a way that the observed changes in elevation and motion of the water along the path of the wave may be used to determine the distribution of phase of the primary and reflected waves along the channel and to measure the damping. The relations between the several aspects of a wave as it advances along a channel of uniform depth and width have been developed theoretically so as to show the times of high water and slack water, the range of the tide, and the phase relations of the primary and reflected waves along the channel for any degree of damping. By expressing the relationship of the several aspects of a reflected wave in a form in which the wave period is taken as the unit of time and distance is given in terms of the related phase changes, it is possible to eliminate the purely geographical dimensions and to obtain a wholly general description of the tide which may be used to indicate how any given channel distorts the behavior of the wave as it advances. In the case of irregular channels, in order to justify the application of relations deduced for uniform channels, in which the change in phase of the primary and reflected waves and their damping is proportional to the distance traveled and in which the velocity of the waves is constant, it is necessary to make the following assumptions: 1. That the effect of irregularities in cross section is to alter the velocity of the primary and reflected waves; i.e., to distort the geographical distribution of phase differences. 2.That damping is proportional to the phase change in the waves rather than to the distance traveled. 3. That the damping coeffcient, as defined, is constant along the length of the channel.
