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71.
Kenneth P. Able William F. Gergits Jeffrey D. Cherry Scott B. Terrill 《Behavioral ecology and sociobiology》1984,15(1):39-43
Summary Using the wood thrush (Hylocichla mustelina) as an example of a typical nocturnal migrant, we employed radio telemetry to follow breeding birds during the course of homing movements following displacements. Seven thrushes were displaced over distances of 6.5 to 17.3 km in a variety of directions from their nesting territories. The thrushes moved in a series of short flights (mean = 2.1 km) performed primarily at dawn. Consequently, the birds took several days to home from even these relatively short displacements. Thrushes flew under clear and solid overcast skies and even in light rain. The pooled individual flights of the birds were significantly oriented in the homeward direction (Fig. 2). Their orientation relative to home did not improve significantly as they progressed toward the goal. Three of the birds were documented to have returned to their home territories. The detailed tracks of the birds preclude the possibility that they homed by random search. 相似文献
72.
Donald S. Cherry Rufus K. Guthrie Ernst M. Davis Raymond S. Harvey 《Journal of the American Water Resources Association》1984,20(4):535-544
ABSTRACT Coal ash effluent effects including particulates, acidic pH excursions, elemental concentrations and bioconcentration in selected organisms have been studied as changes in water quality and densities of benthic macroinvertebrate and mosquitofish (Gambusia affinis) populations in a swamp drainage system over an eight-year period. Three changes in the ash basin settling system were made between mid- 1973 and January 1982. Initial density of the aquatic biota was altered severely by heavy ash siltation, followed by acidic pH excursions and perhaps overall by elemental concentrations and bioaccumulation. Heavy ash siltation, followed by acidic Ph excursions (mean of 5.5, extreme of 3.5) after the addition of fly ash to the original settling basin system, had the most profound effect on biota. Dipterans (chironomids) and some odonates (Plathemis lydia and Libellula spp.) were resistant to heavy ash siltation, while mosquitofish, which showed no discernible responses to ash siltation, were absent at acidic pH, along with the few previously surviving invertebrate populations. Elemental concentrations of arsenic, cadmium, chromium, copper, selenium, and zinc did not appear to limit aquatic flora and fauna on a short-term, acute basis. Long, chronic elemental exposures may have been instrumental in retarding the recovery of all forms of aquatic life in the receiving system. Elemental concentrations (except for arsenic and selenium) in the receiving system were generally one to two orders of magnitude higher than the Water Quality Criteria set by the U.S. Environmental Protection Agency (1980) for protection of aquatic life for the minimum and 24-hour mean values. From collective elemental exposures in the receiving system, bioconcentration factors in macrophytes, invertebrates and fish were generally lower than those reported in the literature for laboratory, single elemental concentrations. By 1978, when the new settling basin systems were operating effectively, invertebrate populations were largely recovered, and mosquitofish populations recovered within one year afterward. 相似文献
73.
Major computer and software companies, along with governments and philanthropic organizations have embarked on ambitious plans to put computers in the hands of more than one billion new computer users over the next five to six years in untapped markets in emerging economies. The most frequently proposed solution to overcome the electricity shortfall in communities where new computer users will be located is to use rechargeable lead-acid batteries to provide primary and back-up power for computers. This paper calculates the lead emissions from battery manufacturing and recycling that will result if independent market projections to greatly expand the number, geographic, and socioeconomic distribution of computer users are realized. By examining several possible scenarios, we estimate that between 1250 and 2300 kt of lead – between four and seven times the weight of the Empire State Building – could be released into the environment in the developing world to provide power to computers sold through 2015. Increased lead exposure has a negative impact on children's neurological development as measured by reduced school performance and on standardized tests. In order to realize the educational achievement and economic development benefits of reducing the “digital divide” proponents will need to encourage improvements in lead battery production and recycling in targeted markets. 相似文献