Measuring the Cosmic Equation of State with Counts of Galaxies     

Newman JA  Davis M 《The Astrophysical journal》2000,536(1):L11-L14

We show that the gas in growing density perturbations is vulnerable to the influence of winds outflowing from nearby collapsed galaxies that have already formed stars. This suggests that the formation of nearby galaxies with masses less, similar10(9) M( middle dot in circle) is likely to be suppressed, irrespective of the details of galaxy formation. An impinging wind may shock-heat the gas of a nearby perturbation to above the virial temperature, thereby mechanically evaporating the gas, or the baryons may be stripped from the perturbation entirely if they are accelerated to above the escape velocity. We show that baryonic stripping is the most effective of these two processes, because shock-heated clouds that are too large to be stripped are able to radiatively cool within a sound crossing time, limiting evaporation. The intergalactic medium temperatures and star formation rates required for outflows to have a significant influence on the formation of low-mass galaxies are consistent with current observations, but may soon be examined directly via associated distortions in the cosmic microwave background and with near-infrared observations from the Next Generation Space Telescope, which may detect the supernovae from early-forming stars.  相似文献   

北美沙漠中一年生植物的分布   总被引：1，自引：0，他引：1  

Ludw.  JA  江伟铮 《世界沙漠研究》1989,(2):14-17

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煤中微量元素的分布模型     

Sola.  JA 余泽宇 《川煤地勘》1990,(8):66-71

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An assessment of the potential use of the nematode to copepod ratio in the monitoring of metals pollution. The Chañaral case     

Lee MR  Correa JA  Castilla JC 《Marine pollution bulletin》2001,42(8):696-701

We discuss the use of the nematode to copepod ratio in relation to determining the extent of metals impact using the Cha?aral area of northern Chile, where the dumping of copper mine tailings has taken place for many years, as an example. Data were collected from 12 beaches in the area on eight occasions between January 1997 and October 1998. We find that the ratio is not a good predictor of pollution due to the generally low densities of meiofauna on impacted beaches and the absence of harpacticoid copepods from those beaches. We suggest that in the case of metal pollution the mean number of Harpacticoida per site may be a better indicator of impact stress. We rule out the use of the nematode to copepod ratio as an indicator in biomonitoring studies where metal enrichment is thought to occur.  相似文献   

Changes in benthic fish assemblages as a consequence of coastal works in a coastal lagoon: The Mar Menor (Spain, Western Mediterranean)   总被引：3，自引：0，他引：3  

Pérez-Ruzafa A  García-Charton JA  Barcala E  Marcos C 《Marine pollution bulletin》2006,53(1-4):107-120

The benthic fish assemblage of the Mar Menor consisted of 37 species. Dominant species are: Gobius cobitis, Lipophrys pavo and Tripterygion tripteronotus on infralittoral rocks; Pomatoschistus marmoratus, Callionymus pussillus, Callionymus risso and Solea vulgaris on sandy bottoms and Gobius niger, Syngnathus abaster, Hippocampus ramulosus and Symphodus cinereus on Cymodocea nodosa-Caulerpa prolifera mixed beds. From 1985 to 1989 tourist development has led to the creation of new beaches and the installation of artificial rocky structures for retaining sediments. Dredging for the extraction of sand and subsequent pumping altered sediment characteristics causing a real stress leading to the substitution of typical sandy bottoms communities with Cymodocea nodosa by Caulerpa prolifera communities on mud. Soft bottom fish assemblages responded to changes in vegetation cover and substratum characteristics mainly changing the species composition, while artificial hard substrata contain a similar fish community than natural ones, harbouring even richer and more diverse assemblages. This positive effect of breakwaters should not obscure their likely negative effects on hydrodynamics and the subsequent changes of sediment quality and vegetation cover on the breakwaters' area of influence.  相似文献   

Monitoring biomarkers in fish (Lepidorhombus boscii and Callionymus lyra) from the northern Iberian shelf after the Prestige oil spill     

Martínez-Gómez C  Campillo JA  Benedicto J  Fernández B  Valdés J  García I  Sánchez F 《Marine pollution bulletin》2006,53(5-7):305-314

Hepatic biomarker responses were measured in two demersal fish species (Lepidorhombus boscii and Callionymus lyra) from the northern Iberian shelf associated with the massive Prestige oil spill (POS), five months after the accident. The biomarkers selected were 7-ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), glutathione reductase (GR), catalase (CAT), and DNA integrity. Interspecies differences and spatial variations in biomarker responses were observed along the shelf. GST, GR and CAT activities were significantly elevated in L. boscii in the most oil impacted area (Finisterre) and positively correlated (p<0.05) with POS tar aggregate densities. The lack of previous data from the area together with the existence of chronic background pollution of the shelf implies that the observed biomarker responses cannot be solely attributed to the petroleum hydrocarbon components of the spilled oil. This first biological effect assessment showed that L. boscii is a potentially suitable target species to be used in future biomonitoring programmes along the northern Iberian shelf.  相似文献   

Quality assurance, information tracking, and consumer labeling     

Caswell JA 《Marine pollution bulletin》2006,53(10-12):650-656

Reducing marine-based public health risk requires strict control of several attributes of seafood products, often including location and conditions of catch or aquaculture, processing, and handling throughout the supply chain. Buyers likely will also be interested in other attributes of these products such as eco-friendliness or taste. Development of markets for improved safety, as well as for other quality attributes, requires an effective certification and tracking of these attributes as well as their communication to buyers. Several challenges must be met if labeling, particularly consumer labeling, is to support the development of markets for improved seafood safety.  相似文献   

粘土矿物对环境污染的防治作用   总被引：8，自引：0，他引：8  

鲁春霞  于云江  吴俊平 《中国沙漠》1999,19(3):265-267

粘土矿物具有比表面积大、孔隙多以及极性强等特征,因而有较强的吸附性、离子交换性和膨胀性,对水体中各种类型的污染物质有良好的吸附性能,并使土壤有一定的自净作用。粘土矿物的膨胀性及低导水率使它能作为有效的密封物质,在放射性废料的埋置过程中产生理想的封闭作用。另外由于粘土矿物成本低、再生容易,所以在环境污染的防治中有广阔的应用前景。  相似文献   

Nordic海和北大西洋冰携层中的非同期沉积     

Dowd.  JA 董丽红 《海洋地质前沿》1999,(10):8-9

一些海洋地质研究已经证实了主要来自赫德森海峡的大量冰山形成了６个快速沉积冰携碎屑（ＩＲＤ）的Ｈｅｉｎｒｉｃｈ层。这些独特的地层厚度为１ｍ至几厘米,在北大西洋可追踪至３０００ｋｍ以下。然而,虽然对Ｎｏｒｄｉｃ海的许多沉积岩心作了验证,但是粗砾层的厚度和Ｈｅｉｎｒｉｃｈ层的空间连续性还是分辨不出来。目前只在某些区域发现了相关的ＩＲＤ事件和某些Ｈｅｉｎｒｉｃｈ事件。Ｆｅｎｎｏｓｃａｎｄｉａｎ、斯瓦巴德—巴伦支海和格陵兰冰盖注出冰川附近的冰心表明,整个Ｎｏｒｄｉｃ海的ＩＲＤ层之间几乎不存在系统的区域相关…  相似文献   

北大西洋罗卡尔海槽北部上第四系地层及古海洋学变化     

Howe.  JA 王宏斌 《海洋地质》1999,(2):28-44,27

运用微化石及沉积学方法,对采自罗卡尔海槽北部不同沉积环境的六个浅层重力管样品进行了层序分析,从采自巴拉扇沉积波的钻孔样品可识别出半远洋、浊流、准浊流沉积层序。从罗卡尔海槽东北部的陆坡裙、海底陆坡到冰碛沉积区内采获的岩芯,是一些半远洋与冰海沉积物,泥质粉砂岩和等深积砂岩与之互层或覆于其上。甲藻类孢子,浮游有孔虫类以及超微生物地层标志,反映了四次冰消作用,巴拉扇的一个长岩芯样记录了这四次冰消作用,即晚  相似文献