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441.
Ramello Gloria Duke Guy Dekker Rene W. R. J. van der Mije Steven Movalli Paola 《Environmental science and pollution research international》2022,29(12):17017-17030
Environmental Science and Pollution Research - This paper provides a novel survey of current collections of frozen raptor carcasses and tissue samples in natural history museums (NHMs),... 相似文献
442.
Implications of Upstream Flow Availability for Watershed Surface Water Supply across the Conterminous United States
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Kai Duan Ge Sun Peter V. Caldwell Steven G. McNulty Yang Zhang 《Journal of the American Water Resources Association》2018,54(3):694-707
Although it is well established that the availability of upstream flow (AUF) affects downstream water supply, its significance has not been rigorously categorized and quantified at fine resolutions. This study aims to fill this gap by providing a nationwide inventory of AUF and local water resource, and assessing their roles in securing water supply across the 2,099 8‐digit hydrologic unit code watersheds in the conterminous United States (CONUS). We investigated the effects of river hydraulic connectivity, climate variability, and water withdrawal, and consumption on water availability and water stress (ratio of demand to supply) in the past three decades (i.e., 1981–2010). The results show that 12% of the CONUS land relied on AUF for adequate freshwater supply, while local water alone was sufficient to meet the demand in another 74% of the area. The remaining 14% highly stressed area was mostly found in headwater areas or watersheds that were isolated from other basins, where stress levels were more sensitive to climate variability. Although the constantly changing water demand was the primary cause of escalating/diminishing stress, AUF variation could be an important driver in the arid south and southwest. This research contributes to better understanding of the significance of upstream–downstream water nexus in regional water availability, and this becomes more crucial under a changing climate and with intensified human activities. 相似文献
443.
Johnston PN Hult M Gasparro J Martínez-Canet MJ Vasselli R McKenzie RJ Solomon SB Lambrichts I 《Journal of environmental radioactivity》2005,80(2):245-257
It is possible to estimate radon exposure to man retrospectively by the in vivo measurement of the decay product (210)Pb, which accumulates in the bones. For in vivo methods, knowledge of the distribution of (210)Pb in the skeleton is needed to determine the optimal site for measurement, the skull or the knee. In this study the activity of (210)Pb in a variety of bone samples from 3 individuals have been measured in vitro using underground gamma-ray spectrometry. The individuals were unlikely to have had elevated intakes of Rn. These measurements give baseline data on the bone massic activity of (210)Pb. They show that the massic activity is similar for each of these people and there are similar massic activities of (210)Pb in the skull and the knee of the 2 individuals for which the skull was measured. Additionally for 2 of the individuals trabecular and cortical bone were separated and massic activities were found to be strongly correlated indicating that the (210)Pb is associated with the hydroxyapatite. 相似文献
444.
Courtney E. Moore Steven P. Loheide II Christopher S. Lowry Jessica D. Lundquist 《Journal of the American Water Resources Association》2014,50(4):1033-1050
Vegetation in subalpine meadows in the Sierra Nevada Mountains is particularly vulnerable to lowering of groundwater levels because wet meadow vegetation is reliant upon shallow groundwater during the dry summer growing season. These ecosystems are especially vulnerable to channel incision as meadow aquifers are hydrologically connected to tributaries, and many have not yet recovered from previous anthropogenic influences. While instream restoration projects have become a common approach, lack of postrestoration monitoring and communication often result in a trial‐and‐error approach. In this study we demonstrate that preimplementation modeling of possible instream restoration solutions, chosen to raise stream stage and subsequently groundwater levels, is a useful tool for evaluating and comparing potential channel modifications. Modeling allows us to identify strategic locations and specific methods. Results show additional sediment depth and roughness on tributaries along with introduced woody debris (simulated by high roughness) on the Tuolumne River are the most effective means of raising stream stage. Results demonstrate that restoration efforts are most efficient in tributary streams. Managers and planners can more efficiently direct resources while minimizing the potential for negative impacts or failed restoration projects by modeling the possible effects of multiple restoration scenarios before implementation. 相似文献
445.
Michael J. Polito Christian S. Reiss Wayne Z. Trivelpiece William P. Patterson Steven D. Emslie 《Marine Biology》2013,160(6):1311-1323
Antarctic krill (Euphausia superba) occupy a key position in the Southern Ocean linking primary production to secondary consumers. While krill is a dominant grazer of phytoplankton, it also consumes heterotrophic prey and the relative importance of these two resources may differ with ontogeny. We used stable isotope analyses to evaluate body size-dependent trophic and habitat shifts in krill during the austral summer around the South Shetland Islands, Antarctica. We found evidence for an asymmetric, ontogenetic niche expansion with adults of both sexes having higher and more variable δ15N values but consistent δ13C values in comparison with juveniles. This result suggests that while phytoplankton likely remains an important life-long resource, krill in our study area expand their dietary niche to include higher trophic food sources as body size increases. The broader dietary niches observed in adults may help buffer them from recent climate-driven shifts in phytoplankton communities that negatively affect larval or juvenile krill that rely predominately on autotrophic resources. 相似文献
446.
Phytoremediation is a promising new method that uses green plants to cleanse soil and water contaminated with organic or inorganic pollutants. In this study, the uptake and transformation of sodium perchlorate (NaClO4) using four vascular plant species were examined in batch experiments. The species include two trees, cabbage gum (Eucalyptus amplifolia) and eastern cottonwood (Populus deltoides), a herbaceous wetland plant, perennial glasswort (Salicornia virginica), and a herbaceous aquatic plant, waterweed (Elodea canadensis). Perchlorate was depleted from solution in the presence of all but one species (waterweed). Depletion was calculated as a first‐order kinetics reaction with k values in the range of 0–0.013 per day and accumulation of perchlorate was between 3.2 and 3138 mg/kg. Perchlorate and transformation metabolites (chlorate, chlorite, chloride) were observed in all plant tissues (e.g., roots, stems, leaves) analyzed. Results suggest that significant influences on perchlorate uptake include: (1) plant species present, (2) concentration of perchlorate, (3) sand versus hydroponic treatments, (4) the presence or absence of plant nutrients or competing ions, (5) stage of plant maturity. 相似文献
447.
448.
Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the
production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result
of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid
wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production
of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric
acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization
of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry.
The 238U, 234U, 226Ra, and 232Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations
in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric
acid D) > Catal?o (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces
a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced
in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola
soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml
of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under
these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft
drinks is not hazardous to human health in Brazil. Considering these annual additions of 238U, 226Ra, 232Th and 40K, and since these radionuclide should be homogeneously distributed in the upper 10 cm of soils with an assumed apparent density
of 1.5 g/cm3, a maximum increase of 0.19 ± 0.03 Bq kg−1 of soil is expected for 238U and 234U. Thus, the addition of solid waste as phosphate fertilizers to Brazilian agricultural soils does not represent a hazard
to the ecosystem or to human health. 相似文献
449.
450.
When eggs hatch asynchronously, offspring arising from last-hatched eggs often exhibit a competitive disadvantage compared
with their older, larger nestmates. Strong sibling competition might result in a pattern of resource allocation favoring larger
nestlings, but active food allocation towards smaller offspring may compensate for the negative effects of asynchronous hatching.
We examined patterns of resource allocation by green-rumped parrotlet parents to small and large broods under control and
food-supplemented conditions. There was no difference between parents and among brood sizes in visit rate or number of feeds
delivered, although females spent marginally more time in the nest than males. Both male and female parents preferentially
fed offspring that had a higher begging effort than the remainder of the brood. Mean begging levels did not differ between
small and large broods, but smaller offspring begged more than their older nestmates in large broods. Male parents fed small
offspring less often in both brood sizes. Female parents fed offspring evenly in small broods, while in large broods they
fed smaller offspring more frequently, with the exception of the very last hatched individual. These data suggest male parrotlets
exhibit a feeding preference for larger offspring—possibly arising from the outcome of sibling competition—but that females
practice active food allocation, particularly in larger brood sizes. These differential patterns of resource allocation between
the sexes are consistent with other studies of parrots and may reflect some level of female compensation for the limitations
imposed on smaller offspring by hatching asynchrony. 相似文献