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131.
Stephan F. J. De Wekker D. G. Steyn J. D. Fast M. W. Rotach S. Zhong 《Environmental Fluid Mechanics》2005,5(1-2):35-62
Data from a comprehensive field study in the Riviera Valley of Southern Switzerland are used to investigate convective boundary layer structure in a steep valley and to evaluate wind and temperature fields, convective boundary layer height, and surface sensible heat fluxes as predicted by the mesoscale model RAMS. Current parameterizations of surface and boundary layer processes in RAMS, as well as in other mesoscale models, are based on scaling laws strictly valid only for flat topography and uniform land cover. Model evaluation is required to investigate whether this limits the applicability of RAMS in steep, inhomogeneous terrain. One clear-sky day with light synoptic winds is selected from the field study. Observed temperature structure across and along the valley is nearly homogeneous while wind structure is complex with a wind speed maximum on one side of the valley. Upvalley flows are not purely thermally driven and mechanical effects near the valley entrance also affect the wind structure. RAMS captured many of the observed boundary layer characteristics within the steep valley. The wind field, temperature structure, and convective boundary layer height in the valley are qualitatively simulated by RAMS, but the horizontal temperature structure across and along the valley is less homogeneous in the model than in the observations. The model reproduced the observed net radiation, except around sunset and sunrise when RAMS does not take into account the shadows cast by the surrounding topography. The observed sensible heat fluxes fall within the range of simulated values at grid points surrounding the measurement sites. Some of the scatter between observed and simulated turbulent sensible heat fluxes are due to sub-grid scale effects related to local topography. 相似文献
132.
Heikens A Widianarko B Dewi IC De Boer JL Seinen W van Leeuwen K 《Environmental geochemistry and health》2005,27(5-6):409-418
In Asembagus (East Java, Indonesia) irrigation water is contaminated with effluent from the hyperacid Ijen Crater Lake resulting
in a low pH and high levels of various elements. As a first step towards a risk assessment, locally produced food items (rice,
maize, cassava leaf, cassava root, peanuts) were collected and concentrations of As, B, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni,
Pb, V, Zn were compared to samples from a reference area and with literature values. Further, concentrations in rice were
compared to total soil concentrations in paddy fields. Compared to the reference area, food items produced in the contaminated
area had increased levels of Cd, Co, Ni and Mn in particular, while levels of Mo were lower. In contrast, total soil concentrations
of Cd and Mn in particular have decreased whereas especially Mo was increased. In combination with the observed soil acidification,
it is likely that the bioavailable concentration of most elements in the contaminated soil is higher (except for Mo) due to
an increased weathering rate and/or input via the contaminated irrigation water. In terms of human health, concentrations in foods were generally within normal literature
values. However, it was observed that essential elements (in particular Fe) known for their inhibitory effects on e.g. Cd
and Mn toxicity did not accumulate in crops whereas Cd and Mn did. 相似文献
133.
S. S. De Silva 《Marine Biology》1973,20(4):282-290
The food and feeding habits of the herring Clupea harengus L. and the sprat C. sprattus (L.) as 0-group and older fish in inshore waters of the west coast of Scotland, were studied from April, 1970 to March, 1972. The two species occurred together. The diets of 0-group herring and sprats are almost identical, both qualitatively and quantitatively. Their daily feeding rhythms also coincide. It is probable that competition between these two species in their first year of life could occur if the food supply is limiting. Changes in diet between 0-group and older fish are more pronounced in herring than in sprats. The diet itself is mainly crustacean in both clupeids, with copepods contributing the major share. 相似文献
134.
Estimating the amounts of resources consumed by individuals is important in many studies. For predators, allometric relationships
can be used to extrapolate the size of preys from undigested remains found in the stomach and in the faeces. However, such
equations are available for a limited number of species. Based on a large sample size gathered in New Caledonia on both predators
(sea kraits) and their preys (anguilliform fishes), we provide the first allometric relationships that allow estimating accurately
the mass and the size of various anguilliform fish species. 相似文献
135.
The major pigment of a marine micro-organism was identified as prodigiosin on the basis of analytical and spectral data. Two minor pigments were tentatively assigned structures, from thin-layer chromatography (TLC) and mass spectral data, as prodigiosin homologs with 3-n-hexyl and 3-n-heptyl side-chains. The micro-organism was classified as a new Pseudomonas species on the basis of its morphological and biochemical characteristics. It was named Pseudomonas magnesiorubra (ATCC No. 21856). 相似文献
136.
中国的太阳能资源及应用潜力 总被引:9,自引:0,他引:9
太阳能资源被认为是21世纪最引人注目的可再生能源和洁净能源,为了经济的可持续发展,应该把环境保护和长期利益作为研究目标,文章估算了中国14个城市的太阳能资源,分析了太阳能热水系统和PIVP系统的经济性,研究结果表明,中国的太阳能利用潜力很大,政府应该对其发展发挥重要作用。 相似文献
137.
本文对谷氨酸生产废水和味精生产废水的性质作了简要介绍,针对该类废水提出了蒸发浓缩+接触氧化为核心的治理工艺。结果表明,经该处理工艺,废水中的COD、BOD5、NH3-N等指标均能够达到《味精工业污染物排放标准》(GB19431—2004)中的标准要求。工艺流程简便可行,效果明显。在实际中有较大应用前景,具有显著的环境和经济效益。本文重点介绍了工程的实际运行情况和运行成本,并进行了简要分析。 相似文献
138.
The effects of chloride, nitrate, perchlorate and sulfate ions on the rates of the decomposition of hydrogen peroxide and the oxidation of organic compounds by the Fenton's process have been investigated. Experiments were conducted in a batch reactor, in the dark at pH < or = 3.0 and at 25 degrees C. Data obtained from Fe(II)/H2O2 experiments with [Fe(II)]0/[H2O2]0 > or = 2 mol mol(-1), showed that the rates of reaction between Fe(II) and H2O2 followed the order SO4(2-) > ClO4(-) = NO3- = Cl-. For the Fe(III)/H2O2 process, identical rates were obtained in the presence of nitrate and perchlorate, whereas the presence of sulfate or chloride markedly decreased the rates of decomposition of H2O2 by Fe(III) and the rates of oxidation of atrazine ([atrazine]0 = 0.83 microM), 4-nitrophenol ([4-NP]0 = 1 mM) and acetic acid ([acetic acid]0 = 2 mM). These inhibitory effects have been attributed to a decrease of the rate of generation of hydroxyl radicals resulting from the formation of Fe(III) complexes and the formation of less reactive (SO4(*-)) or much less reactive (Cl2(*-)) inorganic radicals. 相似文献
139.
The Agency for Toxic Substances and Disease Registry (ATSDR) has a program for chemical mixtures that encompasses research on chemical mixtures toxicity, health risk assessment, and development of innovative computational methods. ATSDR prepared a guidance document that instructs users on how to conduct health risk assessment on chemical mixtures (Guidance Manual for the Assessment of Joint Toxic Action of Chemical Mixtures). ATSDR also developed six interaction profiles for chemical mixtures. Two profiles were developed for persistent environmental chemicals that are often found in contaminated fish and also can be detected in human breast milk. The mixture included chlorinated dibenzo-p-dioxins, hexachlorobenzene, dichlorodiphenyl dichloroethane, methyl mercury, and polychlorinated biphenyls. Two profiles each were developed for mixtures of metals and mixtures of volatile organic chemicals (VOCs) that are frequently found at hazardous waste sites. The two metal profiles dealt with (a) lead, manganese, zinc, and copper; and (b) arsenic, cadmium, chromium, and lead; the two VOCs mixtures dealt with (a) 1,1,1-trichloroethane, 1,1-dichloroethane, trichloroethylene, and tetrachloroethylene; and (b) benzene, ethylbenzene, toluene, and xylenes (BTEX). Weight-of-evidence methodology was used to assess the joint toxic action for most of the mixtures. Physiologically based pharmacokinetic modeling was used for BTEX. In most cases, a target-organ toxicity dose modification of the hazard index approach is recommended for conducting exposure-based assessments of noncancer health hazards. 相似文献
140.
Mills G Ball G Hayes F Fuhrer J Skärby L Gimeno B De Temmerman L Heagle A;ICP Vegetation programme 《Environmental pollution (Barking, Essex : 1987)》2000,109(3):533-542
Results are presented from the UN/ECE ICP Vegetation (International Cooperative Programme on effects of air pollution on natural vegetation and crops) experiments in which ozone(O(3))-resistant (NC-R) and -sensitive (NC-S) clones of white clover (Trifolium repens cv. Regal) were exposed to ambient O(3) episodes at 14 sites in eight European countries in 1996, 1997 and 1998. The plants were grown according to a standard protocol, and the forage was harvested every 28 days for 4-5 months per year by excision 7 cm above the soil surface. Biomass ratio (NC-S/NC-R) was related to the climatic and pollutant conditions at each site using multiple linear regression (MLR) and artificial neural networks (ANNs). Twenty-one input parameters [e.g. AOT40, 7-h mean O(3) concentration, daylight vapour pressure deficit (VPD), daily maximum temperature] were considered individually and in combination with the aim of developing a model with high r(2) and simple structure that could be used to predict biomass change in white clover. MLR models were generally more complex, and performed less well for unseen data than non-linear ANN models. The ANN model with the best performance had five inputs with an r(2) value of 0.84 for the training data, and 0.71 for previously unseen data. Two inputs to the model described the O(3) conditions (AOT40 and 24-h mean for O(3)), two described temperature (daylight mean and 24-h mean temperature), and the fifth input appeared to be differentiating between semi-urban and rural sites (NO concentration at 17:00). Neither VPD nor harvest interval was an important component of the model. The model predicted that a 5% reduction in biomass ratio was associated with AOT40s in the range 0.9-1.7 ppm x h (microl l(-1) h) accumulated over 28 days, with plants being most sensitive in conditions of low NO(x), medium-range temperature, and high 24-h mean O(3) concentration. 相似文献