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31.
The distribution and mode of occurrence of zinc and lead have been examined in glacial soils developed over a complex Precambrian marble-paragneiss terrain in the Adirondack Mountains of New York. Based on distribution within the soil profiles, zinc is enriched in the B1 horizon of soils sampled over marble and lead is generally enriched in the A horizon, particularly in soils developed over paragneiss. Contrast is calculated using
, where is the mean of nA anomalous and nB background samples, and Sp is the pooled standard deviation) for zinc, lead and cold-extractable heavy metals in soils sampled over marble and paragneiss. The t-values indicate that the B1, soil horizon is the most suitable for sampling on a regular basis, even though lead is most concentrated in the A horizon.The distribution of zinc and lead among exchangeable, organic, iron-manganese oxide, clay, silt and sand fractions of B1 horizons from two anomalous and one background soil indicates that both zinc and lead are tied up principally in iron and manganese oxides. The anomalous samples exhibit zinc enrichment in the Fe-oxide digestion and high Mn/Fe ratios for the Mn-oxide digestion (as well as the total analysis). In terms of total contribution to the sample, significant proportions of zinc in the clastic fraction can be attributed to zinc substitution into clays plus the ineffective removal of Fe-oxides by the ammonium oxalate extraction procedure. Lead, on the other hand, occurs in significant concentrations in clay, silt and sand as well as Fe- and Mn-oxides, probably as a trace constituent in feldspars or adsorbed onto clay surfaces.  相似文献   
32.
Dissolved U concentrations and activity ratios (ARs) of the U isotopes in the 238U decay series were measured in ground and surface waters as part of an investigation to delineate the water quality in a proposed uranium mining area of northwest Nebraska. In oxidizing groundwaters from 67 wells completed in the Tertiary sediments, increasing U concentrations in the direction of groundwater flow generally were associated with a maturation of the formation water as evidenced by evolutionary trends in major ion character. The increased U levels probably are associated with leaching as shown by the positive correlation between U concentrations and total dissolved solids (TDS) (r = +0.83). The inverse relationships between TDS and U ARs (r = ?0.73) and U levels and ARs (r = 0.72) indicate that the decay of excess U-234 is related to maturation of the formation water and to sediment leaching along the flowpath. The data are described by a model which incorporates etching, decay and recoil and suggests that aquifer residence time can be estimated from the TDS level.The levels of soluble U in a reducing uraniferous hydrogeologic unit near Crawford, Nebraska are affected by the proximity of the sample collection to ore. In groundwater samples having similar chemistries (Na-SO4 + Cl type), similar Ehs, and collected from a close-knit pattern, U concentrations ranged from 0.01 to 2,037 μg l?1 and ARs ranged from 0.75 to 12.6. This high variability in U levels and ARs is indicative of uranium ore in small areal studies where low ARs almost always are associated with high U concentrations.  相似文献   
33.
Cores and surface samples of peats from the Everglades—Mangrove region of Southern Florida were analyzed for total sulfur and pyritic sulfur. These values were compared with the petrographic-botanical components of the peats as determined from point-counts of oriented microtome sections. Pyrite occurs as individual euhedral crystals, loosely packed framboids, and lenses or crusts of minute crystals. Framboids and minute crystals are often associated with organic matter and sometimes with bacteria and fungi. Pyrite tends to selectively occur in void spaces in or between peat tissues. In samples containing very small amounts of pyrite, framboidal pyrite is the prevalent form.Marine to brackish peats contain the highest pyrite and total sulfur contents, with brackish peats generally containing more pyrite than marine peats. Pyrite tends to be lower in all peats within 30 cm of the surface, whether marine or brackish.Burial of freshwater peats beneath marine or brackish peats tends to increase the total sulfur and pyritic sulfur in the underlying peats. Burial beneath brackish-water, clay-rich deposits (such as splays) tends to increase total sulfur and pyritic sulfur in the underlying deposits more than burial beneath less clay-rich deposits.  相似文献   
34.
It is pointed out that local vibrations of certain members in earthquake excited offshore structures can induce substantial stresses that may often dominate the design of these members. Such vibrations are not accounted for in dynamic analyses of structural models with masses lumped at the joints. A practical, easy to implement solution to this problem is recommended and results from an actual structure, subjected to a three-component real earthquake, are presented demonstrating the importance of local inertia effects.  相似文献   
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In 1978 the California Department of Fish and Game carried out a major, independent sportfishing survey in southern California. The results of that survey indicated that approximately one million angler-trip hours per year were spent fishing and that one in three fish caught was a white croaker (Genyonemus lineatus). There was no attempt by the Department of Fish and Game to determine the disposition of caught fish. We conducted a subsequent survey in 1980 which included 12 popular sportfishing sites in the Los Angeles area. Our results also indicated that one in three fish caught was a white croaker. In addition our survey showed that 82% of the sportfishermen ate the white croaker they caught and the median consumption was 14.8 g day?1 person?1. White croaker were then sampled by hook-and-line from 11 of the 12 survey sites plus two control sites and analysed for PCB, DDT and BaP. Median PCB levels ranged from 0.014 to 0.41 mg wet kg?1; median DDT from 0.059 to 7.5 mg wet kg?1 and BaP was below detectable limits of 1 ng for all sites.  相似文献   
38.
The fossil remains of 43 bowhead whales were mapped on the raised beaches of western Wollaston Peninsula, Victoria Island, Canadian Arctic, near the historic summer range limit of the Bering Sea stock in the Beaufort Sea. The elevations and radiocarbon ages of the remains demonstrate that the bowhead ranged commonly into the region following the submergence of Bering Strait at ca. 10,000 14C yr B.P. until ca. 8500 14C yr B.P. During the same interval, bowheads ranged widely from the Beaufort Sea to Baffin Bay. Subsequently, no whales reached Wollaston Peninsula until ca. 1500 14C yr B.P. Late Holocene populations evidently were small, or occupations were brief, in comparison to those of the early Holocene. Although the late Holocene recurrence may relate to the expansion of pioneering Thule whalers eastward from Alaska, there are few Thule sites and limited evidence of Thule whaling in the area surveyed to support this suggestion.  相似文献   
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Zusammenfassung Die Ergebnisse von Untersuchungen über das Grobaerosol (Partikelgröße über 0.5 ) in einer Großstadt (Hamburg), wurden mit Hilfe modernster statistischer Verfahren eingehend bearbeitet. Eine ursprünglich durchgeführte grobe Bearbeitung, wie sie heute noch von den meisten Meteorologen vorgenommen wird, ergab praktisch nur eine Abhängigkeit von den Jahreszeiten (Heizperiode) und von den Inversionslagen.Mit Hilfe moderner statistischer Methoden war es u. a. möglich, statistisch gesicherte Abhängigkeiten der Partikelzahlen und Partikelgrößen von der Windrichtung, der Partikelzahlen von der Windstärke und der Partikelzahlen von den Luftkörpern, aufzudecken. Auch ein statistisch gesicherter Zusammenhang zwischen der Sichtweite und der Partikelzahl des Grobaerosols konnte festgestellt werden.Diese Untersuchungen zeigen deutlich die Vorteile und die Notwendigkeit der Bearbeitung von Meßreihen mit den neuen Verfahren der mathematischen Statistik.  相似文献   
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