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81.
Russell LM Rasch PJ Mace GM Jackson RB Shepherd J Liss P Leinen M Schimel D Vaughan NE Janetos AC Boyd PW Norby RJ Caldeira K Merikanto J Artaxo P Melillo J Morgan MG 《Ambio》2012,41(4):350-369
Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO(2)) removal (CDR), which removes CO(2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research. 相似文献
82.
Peter K. Mueller Margaret Hitchcock 《Journal of the Air & Waste Management Association (1995)》2013,63(9):677-678
The ultimate aim of toxicological studies is to determine the effects of pollutants on the health and welfare of human beings. To get this it is essential to conduct animal studies to evaluate the potential toxicity of different pollutants. Toxicological appraisal of the photochemical oxidant type of air pollution shows: (1) The effects are primarily on the lungs and the senses. (2) There is impairment of pulmonary function in humans at concentrations found in polluted air. (3) Both ozone and nitrogen dioxide tend to oxidize in animals the lung tissue for a time. This process creates agents which have the potential for cross-linking structural proteins, and this process initiates inflammation which accelerates cell turnover rates. Both crosslinking and cell turnover rates are factors in aging, which may thus be accelerated by years of repeated exposure to oxidants. (4) Long-term exposure to low levels of nitrogen dioxide can produce pre-emphasematous lesions in the lungs of rats and mice. Studies with other species are needed. (5) Ozone, nitrogen dioxide, and dilute irradiated car exhausts increase susceptibility to respiratory infection. The constant search for more sophisticated and sensitive techniques to detect subtle changes indicative of pre-disease conditions should not be relaxed. Such techniques will provide chronic disease predictors of great relevance as air quality criteria. 相似文献
83.
Sujeeva Setunge Kee Kong Wong Margaret Jollands 《Water, Air, & Soil Pollution: Focus》2009,9(5-6):485-494
Annually, sawmills and other wood-processing factories generate a significant amount of scrap materials which are sent to landfills or incinerated. The amount of residue generated in Australia annually is estimated at 200,000 tonnes. A research project conducted at RMIT University explored utilizing these waste materials as particleboard furnish. The research team has now established a methodology for making particleboard in the laboratory using 100% hardwood sawmill residues, developing a particleboard product made in the laboratory which has acceptable mechanical properties and density profiles in accordance with the Australian Standards. However, this board product has some perceived issues which have been hindering ready commercial uptake. The current product requires a 10% higher resin load, has a 10% higher board density, and requires 10% longer pressing times compared to normal softwood particleboard. The paper presents an analysis of the current production process of particleboard to investigate the economic feasibility of particleboard production using hardwood sawmill residues. A major challenge in the analysis is converting the environmental benefit of utilizing large quantities of sawmill residue to a monetary term. Investigation of the global impact of particleboard by considering emission of carbon dioxide to the atmosphere is also included. A comparison is presented between different methods of disposing wood residues to understand the environmental benefit of using hardwood residue in particleboard. 相似文献
84.
Klinefelter syndrome (KS) or 47,XXY is the most common sex chromosome aneuploidy (SCA), occurring at a prevalence of 1 in 600 male pregnancies. Historically, only 25% of individuals with KS came to medical attention, for a range of issues across the life course including under-virilisation at birth, developmental and social concerns in childhood, absence, delay or arrest of puberty in adolescence or infertility in adulthood. Our understanding of the phenotypic spectrum of KS has been largely influenced by this ascertainment bias. With increasing uptake of antenatal noninvasive prenatal testing (NIPT), a corresponding increase in identification of KS has been documented. Population-based longitudinal data from infancy to adulthood on these individuals is lacking, which impedes balanced antenatal genetic counselling and raises issues for prospective parents and clinicians alike. 相似文献
85.
For marine invertebrates, larval developmental mode is inseparably linked to the nutritional content of the egg. Within the
asterinid family of sea stars there have been multiple, independent, evolutionary transitions to lecithotrophic development
from the ancestral, planktotrophic state. To investigate the evolution of maternal investment and development within the Asterinidae,
we quantified individual lipid classes and total protein for eggs and larval stages of closely related species representing
three developmental modes (planktotrophy, planktonic lecithotrophy and benthic lecithotrophy). Within species, maternal provisioning
differed between females indicating that egg quality varied with parentage. Maternal investment was related to egg size but,
after correcting for egg volume, we identified two major oogenic modifications associated with the evolution of lecithotrophic
development: (1) a reduction in protein deposition that probably reflects the reduced structural requirements of nonfeeding
larvae, (2) an increase in deposition of a single class of energetic lipid, triglyceride (TG). The exception was Parvulastra exigua, which has benthic, lecithotrophic development and lays eggs with a lipid to protein ratio close to that of planktotrophs.
This oogenic strategy may provide P. exigua larvae with a protein “weight-belt” that assists in maintaining a benthic existence. Asterinids with planktotrophic development
used a significant portion of egg TG to build a feeding bipinnaria larva. For Meridiastra mortenseni, female-specific differences in egg TG were still evident at the bipinnaria stage indicating that egg quality has flow-on
effects for larval fitness. In lecithotrophic asterinids, TG reserves were not depleted in development to the larval stage
whereas protein stores may help fuel early larval development. Available data indicate that there may be two evolutionarily
stable egg lipid profiles for free-spawning, temperate echinoderms. 相似文献
86.
Beatrice Oneda Rosa Baldinger Regina Reissmann Irina Reshetnikova Pavel Krejci Rahim Masood Nicole Ochsenbein-Kölble Deborah Bartholdi Katharina Steindl Denise Morotti Marzia Faranda Alessandra Baumer Reza Asadollahi Pascal Joset Dunja Niedrist Christian Breymann Gundula Hebisch Margaret Hüsler René Mueller Elke Prentl Josef Wisser Roland Zimmermann Anita Rauch 《黑龙江环境通报》2014,34(6):525-533
87.
Vincent Wai Tsun Li Mei Po Mirabelle Tsui Xueping Chen Michelle Nga Yu Hui Ling Jin Raymond H. W. Lam Richard Man Kit Yu Margaret B. Murphy Jinping Cheng Paul Kwan Sing Lam Shuk Han Cheng 《Environmental science and pollution research international》2016,23(9):8275-8285
The negative effects of overexposure to ultraviolet (UV) radiation in humans, including sunburn and light-induced cellular injury, are of increasing public concern. 4-Methylbenzylidene camphor (4-MBC), an organic chemical UV filter, is an active ingredient in sunscreen products. To date, little information is available about its neurotoxicity during early vertebrate development. Zebrafish embryos were exposed to various concentrations of 4-MBC in embryo medium for 3 days. In this study, a high concentration of 4-MBC, which is not being expected at the current environmental concentrations in the environment, was used for the purpose of phenotypic screening. Embryos exposed to 15 μM of 4-MBC displayed abnormal axial curvature and exhibited impaired motility. Exposure effects were found to be greatest during the segmentation period, when somite formation and innervation occur. Immunostaining of the muscle and axon markers F59, znp1, and zn5 revealed that 4-MBC exposure leads to a disorganized pattern of slow muscle fibers and axon pathfinding errors during the innervation of both primary and secondary motor neurons. Our results also showed reduction in AChE activity upon 4-MBC exposure both in vivo in the embryos (15 μM) and in vitro in mammalian Neuro-2A cells (0.1 μM), providing a possible mechanism for 4-MBC-induced muscular and neuronal defects. Taken together, our results have shown that 4-MBC is a teratogen and influences muscular and neuronal development, which may result in developmental defects. 相似文献
88.
Reproduction of Holothuria fuscogilva (Selenka, 1867) in the Solomon Islands was investigated over a 4 yr period (1994 to 1998) by macroscopic and microscopic
examination of the gonad tubules, the gonad index (GI) method, histological examination of gametogenesis, and spawning-induction
trials. The gonad consisted of numerous tubules that dominated the coelom of gravid specimens. New tubules appeared in March,
and grew in size and extent of branching until they reached their maximum size and maturity in August. Spawning occurred from
August to October, with the majority of gametes released during October, although it was only partial in many individuals.
After spawning, the tubules appeared wrinkled and resorbed into the gonad basis. A five-stage gonad maturity scale based on
the macroscopic appearance of the gonad tubules corresponded with discrete stages of gametogenesis identified by histology.
Gametogenesis was initiated in mid-March, with oogenesis and spermatogenesis occurring in parallel, followed by the growing
stage (May to July) which was marked by active gamete development. Successful induction of spawning during the breeding period
corroborated the GI and histological data. The uniform growth of gonad tubules indicated that H. fuscogilva in the Solomon Islands does not conform to the progressive tubule recruitment model described for other holothurians. An
important application of this study is that the appearance of gonad tubules, removed by biopsy, can be used to determine the
gonad condition of wild adults or captive broodstock.
Received: 28 June 1999 / Accepted: 8 March 2000 相似文献
89.
90.
Electron backscatter diffraction (EBSD) is a powerful microscopic technique to characterise the crystallography of biomineralisation. Here, we use high-resolution EBSD to characterise one of the least studied shells in the ocean, the female argonaut brood chamber, and to examine the changes in shell microstructure in response to incubation in decreased pH conditions. The thin (225 μm) shell of Argonauta nodosa is magnesium calcite with an average magnesium content of ca. 5.1 Wt % MgCO3. EBSD and scanning electron microscopy (SEM) revealed that calcification of the shell is bidirectional with formation of irregular crystalline grains. Following a 2 week incubation in a range of pH treatments (pH, 8.1–7.2), shell fragment weight decreased by dissolution in pH ≤ 7.8. EBSD and SEM revealed altered shell crystallography and microstructure at pH ≤ 7.4 due to preferential etching down crystallite grain boundaries and a change in crystalline orientation on both the inner and outer shell surfaces. Our study highlights the value of EBSD for the detailed examination of biogenic carbonates and its potential use in the field of ocean acidification research. 相似文献