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961.
This study describes an effort to estimate atmospheric mixing height using vertical profiles of thermodynamic variables measured operationally at radiosonde sites in South Korea. We focus on mixing height at 06UTC (15LST) when vigorous daytime convection is expected with clear skies. For this purpose, we developed a simple numerical algorithm using a new data transfer tool, known as cURL, to determine mixing height and applied it to radiosonde data at Osan and Gwangju for 2010. Emphasis was placed on automating as much as possible the process of determining mixing height. According to the preliminary results, the estimation algorithm performed successfully for most cases with clear sky conditions and was useful in diagnosing and monitoring daytime mixing heights more effectively on a near-real-time basis. With the developed algorithm, it is possible to estimate mixing heights from radiosonde data within a few hours of the development of the convective boundary layer. Application to radiosonde sites in other countries is straightforward and continued modifications of the algorithm are anticipated in the near future. 相似文献
962.
Ha-il Jung Jinwook Lee Mi-Jin Chae Myung-Suk Kong Chang-Hoon Lee Seong-Soo Kang Yoo-Hak Kim 《Environmental monitoring and assessment》2017,189(12):638
Arsenic (As) accumulation in rice owing to uptake from the soil is a critical human health issue. Here, we studied the chemical properties of As-treated soils, growth inhibition patterns of As-stressed rice plants, changes in the As content of soil and soil solutions, and the relationship between As accumulation and As transfer factor from the soil to the rice organs. Rice plants were cultivated in a greenhouse under four concentrations of As: 0 (control), 25, 50, and 75 mg kg?1. A significant positive correlation was found between available P2O5 and exchangeable K and between As concentration and available P2O5 or exchangeable K. The As concentration for 50% shoot growth inhibition was 50 mg kg?1. As levels in roots and shoots were positively correlated with the growth stages of rice. The transfer factor (TF)root/soil increased with As concentration at the tillering stage but decreased at the heading stage. TFroot/soil and TFshoot/soil were higher at the heading stage than at the tillering stage. As accumulation in the 25 mg kg?1 treatment was higher during the heading stage, whereas no difference was found at the tillering stage. As accumulation was related to plant biomass and soil As concentration. We found that As accumulation was greater at As concentrations that allowed for plant growth and development. Thus, species-specific threshold concentrations must be determined based on As phytotoxicity for the phytoremediation of As-contaminated soils. Hence, developing practical approaches for managing safe crop production in farmlands with an As contamination of 25 mg kg?1 or less is necessary. 相似文献
963.
To better understand the feeding and reproductive ecology of euphausiids (krill) in different ocean environments, lipid classes
and individual lipid components of four different species of euphausiids from Northeast Pacific (temperate species) and Southern
Ocean (Antarctic species) were analyzed in animals from multiple life stages and seasons. The dominant krill species in the
Northeast Pacific Euphausia pacifica and Thysanoessa spinifera, were compared to the two major Antarctic species, Euphausia superba and E. crystallorophias. Analysis comprised total lipid and lipid classes together with individual fatty acid and sterol composition in adults, juveniles,
and larvae. Antarctic krill had much higher lipid content than their temperate relatives (10–50 and 5–20% of dry mass for
Antarctic and temperate species, respectively) with significant seasonal variations observed. Phospholipids were the dominant
lipid class in both temperate krill species, while neutral storage lipids (wax esters and triacylglycerols for E. crystallorophias and E. superba, respectively) were the major lipid class in Antarctic krill and accounted for up to 40% of the total lipid content. Important fatty acids, specifically 16:0, 18:1ω9, 20:5ω3, and 22:6ω3, were detected in all four krill species, with minor
differences between species and seasons. Detailed lipid profiles suggest that krill alter their lipid composition with life
stage and season. In particular, larval Antarctic krill appear to utilize alternate food resources (i.e., sea-ice associated
organisms) during austral winter in contrast to juveniles and adults (i.e., seston and copepods). Lipid dynamics in krill
among krill in both systems appear closely linked to their life cycle and environmental conditions including food availability,
and can provide a more complete comparative ecology of euphausiids in these environmentally distinct systems. 相似文献
964.
Jeffrey Burton Marliave Kim W. Conway Donna M. Gibbs Andy Lamb Charles Gibbs 《Marine Biology》2009,156(11):2247-2254
In the Strait of Georgia and Howe Sound, British Columbia, colonies of individual cloud sponges, growing on rock (known as
sponge gardens) receive resource subsidies from the high biodiversity of epifauna on adjacent rock habitats. Bioherms are
reefs of glass sponges living on layers of dead sponges. In the same area as the sponge gardens, newly discovered bioherms
in Howe Sound, BC (49.34.67 N, 123.16.26 W) at depths of 28- to 35-m are constructed exclusively by Aphrocallistes vastus, the cloud sponge. The sponge gardens had much higher taxon richness than the bioherms. The sponge garden had 106 species from 10 phyla, whereas
the bioherm had only 15 species from 5 phyla. For recruiting juvenile rockfish (quillback, Sebastes maliger), the food subsidy of sponge gardens appears to be missing on bioherms of cloud sponge, where biodiversity is relatively
low. While adult and subadult rockfishes (S. maliger, S. ruberrimus, S. proriger, and S. elongatus) were present on bioherms, no evidence for nursery recruitment of inshore rockfishes to bioherms was observed, whereas the
sponge gardens supported high densities of newly recruited S. maliger, perhaps owing to the combination of both refuge and feeding opportunities. These results indicate that sponge gardens form
a habitat for early stages of inshore S. maliger, whereas A. vastus bioherms are associated only with older juvenile and adult rockfishes. 相似文献
965.
We observed kelp gametophytes endophytic in the cell walls of 17 species of red algae from the San Juan Islands, Washington,
USA. Host algae were collected primarily from three sites dominated by different kelp assemblages, including (1) a subtidal
site dominated by Agarum fimbriatum Harvey, (2) a second subtidal site dominated by Nereocystis luetkeana (Mertens) Postels et Ruprecht, and (3) a floating dock on which the dominant kelp species were Alaria marginata Postels et Ruprecht, Laminaria groenlandica Rosenvinge, and Costaria costata (C. Agardh) Saunders. Most hosts were filamentous [e.g. Pleonosporium vancouverianum (J. Agardh) J. Agardh, Callithamnion acutum Kylin], or polysiphonous [e.g. Polysiphonia paniculata Montagne, Pterosiphonia dendroidea (Montagne) Falkenberg]; however, similar endophytes were also observed in membranous or bladed red algae [e.g. Membranoptera platyphylla (Setchell et Gardner) Kylin, Polyneura latissima (Harvey) Kylin]. Dozens to hundreds of separate kelp gametophytes were associated with single host thalli. In many cases,
the gametophytes developed conspicuous oogonia raised above the thallus surface on characteristic stalks. Presumed zygotes
developed through typical embryonic stages into juvenile sporophytes. We argue that the endophytic habit plays an important
role in the biology of kelp gametophytes.
Received: 5 May 1998 / Accepted: 6 May 1999 相似文献
966.
Results of field experiments using the Virginia Institute of Marine Science' Sea Carousel and tripod system reveal a highly dynamic sediment activity at the Clay Bank site in the York River. At the water-sediment interface, the critical bed shear stress for sediment erosion varied between 0.026 Pa and 0.1 Pa. For the well consolidated sediment below the interface, the critical bed shear stress increased significantly, to more than 0.6 Pa. The seasonal variation of erosion rate for the surficial sediment is significant. For the well consolidated sediment below the surficial sediment, however, the seasonal variation diminished and erosion rate approached a constant. Experimental results from the Carousel deployments imply that the erosion process for quasi-steady tidal flows is always near equilibrium. For this reason, a constant rate erosion model is proposed for the time during tidal acceleration phases. For other times, the erosion rate would be zero. The measured suspended sediment concentration at 10 cm above bed from the VIMS tripod system also Supports this model. 相似文献
967.
968.
Tanya Pankiw Robert E. Page Jr M. Kim Fondrk 《Behavioral ecology and sociobiology》1998,44(3):193-198
Foraging and the mechanisms that regulate the quantity of food collected are important evolutionary and ecological attributes
for all organisms. The decision to collect pollen by honey bee foragers depends on the number of larvae (brood), amount of
stored pollen in the colony, as well as forager genotype and available resources in the environment. Here we describe how
brood pheromone (whole hexane extracts of larvae) influenced honey bee pollen foraging and test the predictions of two foraging-regulation
hypotheses: the indirect or brood-food mechanism and the direct mechanism of pollen-foraging regulation. Hexane extracts of
larvae containing brood pheromone stimulated pollen foraging. Colonies were provided with extracts of 1000 larvae (brood pheromone),
1000 larvae (brood), or no brood or pheromone. Colonies with brood pheromone and brood had similar numbers of pollen foragers,
while those colonies without brood or pheromone had significantly fewer pollen foragers. The number of pollen foragers increased
more than 2.5-fold when colonies were provided with extracts of 2000 larvae as a supplement to the 1000 larvae they already
had. Within 1 h of presenting colonies with brood pheromone, pollen foragers responded to the stimulus. The results from this
study demonstrate some important aspects of pollen foraging in honey bee colonies: (1) pollen foragers appear to be directly
affected by brood pheromone, (2) pollen foraging can be stimulated with brood pheromone in colonies provided with pollen but
no larvae, and (3) pollen forager numbers increase with brood pheromone as a supplement to brood without increasing the number
of larvae in the colony. These results support the direct-stimulus hypothesis for pollen foraging and do not support the indirect-inhibitor,
brood-food hypothesis for pollen-foraging regulation.
Received: 5 March 1998 / Accepted after revision: 29 August 1998 相似文献
969.
Modeling of road traffic noise and estimated human exposure in Fulton County, Georgia, USA 总被引:1,自引:0,他引:1
Seong JC Park TH Ko JH Chang SI Kim M Holt JB Mehdi MR 《Environment international》2011,37(8):1336-1341
Environmental noise is a major source of public complaints. Noise in the community causes physical and socio-economic effects and has been shown to be related to adverse health impacts. Noise, however, has not been actively researched in the United States compared with the European Union countries in recent years. In this research, we aimed at modeling road traffic noise and analyzing human exposure in Fulton County, Georgia, United States. We modeled road traffic noise levels using the United States Department of Transportation Federal Highway Administration Traffic Noise Model implemented in SoundPLAN?. After analyzing noise levels with raster, vector and fa?ade maps, we estimated human exposure to high noise levels. Accurate digital elevation models and building heights were derived from Light Detection And Ranging survey datasets and building footprint boundaries. Traffic datasets were collected from the Georgia Department of Transportation and the Atlanta Regional Commission. Noise level simulation was performed with 62 computers in a distributed computing environment. Finally, the noise-exposed population was calculated using geographic information system techniques. Results show that 48% of the total county population [N=870,166 residents] is potentially exposed to 55 dB(A) or higher noise levels during daytime. About 9% of the population is potentially exposed to 67 dB(A) or higher noises. At nighttime, 32% of the population is expected to be exposed to noise levels higher than 50 dB(A). This research shows that large-scale traffic noise estimation is possible with the help of various organizations. We believe that this research is a significant stepping stone for analyzing community health associated with noise exposures in the United States. 相似文献
970.
Seong-Wan Kang Jong-In Dong Jong-Min Kim Woo-Chan Lee Won-Gu Hwang 《Journal of Material Cycles and Waste Management》2011,13(3):180-185
Various research has attempted to determine the proper treatment of sewage sludge, including thermal technologies. Efficient
thermal technologies have been focused on because of their energy saving/energy recovery. Gasification technology can be considered
one of these approaches. In this study, the characteristics of gasification reactions were investigated with the aim of finding
fundamental data for utilizing sewage sludge as an energy source. For the experiments on sewage sludge gasification reaction
characteristics, a laboratory-scale experimental apparatus was set up with a fluidizing bed reactor of 70-mm inner diameter
and 600-mm total height using an electric muffle furnace. The experimental materials were prepared from a sewage treatment
plant located in Seoul. The reaction temperature was varied from 630 to 860°C, and the equivalence ratio from 0.1 to 0.3.
The gas yields, compositions of product gas, and cold gas efficiencies of product gas were analyzed by GC/TCD and GC/FID installed
with a carboxen-1000 column. The experimental results indicated that 800°C, ER 0.2 was an optimum condition for sewage sludge
gasification. The maximum yield of product gas was about 44%. Producer gas from experiments was mainly composed of hydrogen,
carbon monoxide, carbon dioxide, and methane. The cold gas efficiency of sewage sludge gasification was about 68%. The H2/CO ratio and CO/CO2 ratio were about 1.1 and 1.4, respectively, in optimum reaction conditions. Gaseous pollutants such as SO2, HCl, NH3, H2S, and NO2 were also analyzed at various gasification/combustion conditions, and their gaseous products were compared, showing significantly
different oxidized product distributions. 相似文献