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S. Evren 《Astrophysics and Space Science》1985,108(1):113-123
The RS CVn-type eclipsing binary star MM Her has been observed in two colours,B andV, in 1979, 1980, and 1983. Several minima times were obtained during the observations and new light elements calculated. The light curves of the system obtained in blue and yellow lights show a significant wave-like distortion which migrates towards the decreasing orbital phases. Its migration period was estimated to be about 3.5 yr. The amplitudes of the wave-like distortion inB andV appear to change each year. The primary minimum of the system is a total eclipse with a duration of 0d.08. 相似文献
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Surface waters of Alsea Bay, an unpolluted estuary on the Oregon coast, were analysed for nitrous oxide, nitrate and nitrite on a weekly or biweekly basis during the summer of 1979. The estuary was found to be a variable source of N2O to the atmosphere. Large and rapid increases in the concentrations of N2O, NO3?, and NO2? occurred at the beginning of the sampling period and are attributed to the influx of nutrient-rich upwelling water into the estuary with the tide. The subsequent decline in concentrations of nitrate, nitrite and nitrous oxide over the remainder of the summer is attributed to a decrease in upwelling intensity, a decline in nitrification rates and to assimilatory nitrate reduction. Measurements of nitrous oxide at six stations along the Alsea River were also made in September and October before and after the onset of the rainy season. Samples taken after flood conditions were established were systematically 50% higher than pre-flood samples. The data suggest that soil runoff results in elevated concentrations of N2O in rivers. 相似文献
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Alan M Bond Julie R Bradbury Henry A Hudson John S Garnham Peter J Hanna Stanley Strother 《Marine Chemistry》1985,16(1):1-9
Evidence was found that uptake of lead from seawater in both model and natural systems by the leaves of the seagrass Zostera muelleri does occur for live, dead and scraped leaves at all the lead concentrations tested. Positive uptake of lead was measured using the three analytical techniques of radio-tracer, differential pulse anodic stripping voltammetry and atomic absorption spectrometry; similar uptake profiles were obtained for each technique. Profiles always showed an initial rapid uptake phase followed by a gradual transition to a plateau phase at which an approximate equilibrium between lead attached to seagrass and free ionic lead in seawater was reached. The presence of active lead uptake processes was indicated in experiments which attempted to remove lead from leaves by a chelating agent. 相似文献
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Farmland on the Downs between Lewes and Brighton suffered severe erosion during the autumn of 1982. The erosion was widespread and affected a variety of topographic situations, but it was confined to areas of arable land and recently-sown grass leys. Erosion on the scale recorded during the autumn of 1982 has never previously been recorded from this area. Three major sites of erosion are described and explanations for the erosion are sought through an analysis of rainfall conditions experienced during autumn 1982 and in recent changes in agricultural land use on the Downs. It is concluded that, whilst total rainfall and the intensity of rainstorms were both unusually high, similar events are likely to recur several times a century. Evidence is presented which suggests that the ploughing up of permanent pasture, the removal of field boundaries and the increased adoption of autumn-sown cereals have all contributed to the onset of severe erosion. It appears that a major re-activation of erosion on the Downs may be commencing which threatens the long-term viability of farming in the area. 相似文献
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