全文获取类型
收费全文 | 81篇 |
免费 | 10篇 |
国内免费 | 15篇 |
专业分类
地球物理 | 38篇 |
地质学 | 45篇 |
海洋学 | 19篇 |
综合类 | 2篇 |
自然地理 | 2篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 1篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有106条查询结果,搜索用时 437 毫秒
51.
Dominance of point source in heavy metal distributions in sediments of a major Sydney estuary (Australia) 总被引:1,自引:0,他引:1
Size-normalized (<63 μm) distributions of Cu, Zn, and Pb in the surficial sediments of one of Sydneys' four major estuaries
– the Georges River/Botany Bay estuary – are not facies or depositionally controlled, but rather their distribution is dominated
by source. Point sources (waste dumps, sewage overflows, and discharge from a polluted river) are responsible for elevating
sediment heavy-metal concentrations up to 50 times above background. Nonpoint sources contribute in raising baseline levels
to four times background and comprise mainly stormwater and also marinas, moorings, and wharfs/jetties. Heavy metals disgorged
from a point source (Cooks River) strongly impact the sediments in the lower estuary, which has implications for the construction
of a new runway for Sydney airport.
Received: 3 October 1994 · Accepted: 21 September 1995 相似文献
52.
The sediment record, as revealed in sediment cores, can be used to reconstruct the history of contaminant input into estuaries. The basic assumptions are that contaminant inputs equilibrate relatively rapidly with sediment inputs and that the sediment column represents a continuous sequence of sediment and associated contaminant accumulation. With radiochemical chronologies, it is possible to date sediments over a period corresponding to about five half-lives (100 years for 210Pb). In our study we reconstruct the pollution history of the Savannah Estuary, which is a typical estuary in the South Atlantic Bight. A series of cores were taken in the estuary, followed by the analysis of the cores for a variety of organic and inorganic contaminants. Ages were assigned to different depth intervals by the use of two radiotracers, 210Pb and 137Cs. The major pesticides found were an isomer of DDT and dieldrin. The peak in their concentrations (1967) correlated with peak use of these pesticides before their use was banned. Between 1959 and 1962, there was more input of anthropogenic PAHs than before and after this period. The metals which showed significant changes in the cores include mercury, lead and chromium. Chromium reached a maximum during the late 1950s, followed by a decrease in the late 1960s. This chromium peak coincided with the initial operation of a titanium dioxide pigment plant in the Savannah Estuary. An interesting aspect of the study, which has been noted by many pollution history studies, was the decrease in the concentration of anthropogenic chemicals during the past two decades, suggesting that pollution controls have been effective, even while industrial and population growth was taking place.Similar studies have been carried out to reconstruct the historical record of contamination in the Baltic Sea. Concentrations of metals were found to increase after 1880 (industrial revolution in northern Europe). PCBs peaked in concentration in the late 1960s and the early 1970s, while DDT peaked in the 1960s. The Baltic experienced a major input of nutrients (N and P) after 1965 resulting from heavy use of fertilizers in this region. 相似文献
53.
Contaminated ground and contaminated estuary sediment illustrated by two case histories 总被引:1,自引:0,他引:1
Contaminated ground forms a problem in all of the industrialized countries of the world. Contaminated ground may give rise
to hazards and that implies a degree of risk which also involves a problem of definition. The investigation of a site which
is suspected of being contaminated differs somewhat from a routine site investigation. Sampling of soil, groundwater and gas-producing
material may be required. Various precautions may be necessary to do this and personnel may have to wear protective clothing.
The first case history considered involves a site investigation for a relief sewer in Glasgow. As the site investigation progressed
it ran into made-ground which contained chemical waste. The presence of this waste meant that the nature of the investigation
changed and much more stringent safety precautions had to be taken. It also meant that the initial location of the sewer tunnel
had to be repositioned at greater depth in uncontaminated sandstone rather than in the superficial deposits above.
The other case history considers the contamination of sediments in the Forth Estuary. When trace metals are released into
the water column they can be transferred rapidly to the sediment phase by adsorption onto suspended particulate matter, followed
by sedimentation. Intertidal flats may be considered as important trace metal sinks since they accumulate large amounts of
suspended matter. Hence, in polluted estuaries the deposition of suspended particles on intertidal flats may thus cause severe
contamination. The Forth Estuary has unique contamination for British estuaries; it is experiencing significant Hg pollution.
In addition, due to the presence of a nuclear submarine base in the Forth Estuary, 60Co is detectable in the intertidal sediments. Temporal and spatial contamination patterns were analysed in relation to historical
and present pollution point sources. The effect of fluvial and marine sediment mixing on trace metals and other processes
controlling contaminant levels is reviewed. Preliminary results on quantifying sediment accretion rates using Caesium levels
are discussed.
Received: 9 August 1996 · Accepted: 17 December 1996 相似文献
54.
S. Santiago R. L. Thomas G. Larbaigt C. Corvi D. Rossel J. Tarradellas D. J. Gregor L. McCarthy J. P. Vernet 《Aquatic Sciences - Research Across Boundaries》1994,56(3):220-242
The environmental quality of the Rhone River (Switzerland-France) has been assessed with a geochemical survey of the pollutants bound to suspended sediments. Ten samples were collected between Lake Geneva and the Mediterranean Sea in Nobember 1989 by continuous flow centrifugation and analysed for grain size distribution, carbonate, organic C, N, forms of particulate P, trace metals, and organic compounds (chlorobenzenes, organochlorine pesticides, PCBs, and PAHs). Four bed sediment samples were also studied for comparative purposes. The suspended solids provide lower variance by parameter than the bed sediments and are clearly most suitable for synoptic monitoring.The Upper Rhone River carries a glacial derived sediment with a low nutrient content, the stretch from Geneva to Lyon provides a sediment dominated by carbonate, and in the Lower Rhone the organic matter and phosphorus are relatively increased, mainly due to wastewater effluents and to an industrial P source. High concentrations of metals and organic micropollutants downstream of Lyon indicate a multiple contamination in the Lower Rhone, whereas more specific inputs are located downstream of Geneva and Arles.The comparison with data from other polluted major systems, the Rhine, the Niagara and the Detroit rivers, shows on overall similarity confirming that the Rhone quality is degraded downstream of Lyon. The levels of particular concern are for Hg, DDT metabolites which reveal a recent release in the basin, PCBs with a likely high chlorine content, and PAHs.The statistical evaluation of the compositional variables indicates a limited number of well defined associations, suggesting that the contamination of the suspended sediments results from the combination of numerous and intermittent point and diffuse sources in the Rhone River basin. 相似文献
55.
Contributing to marine pollution by washing your face: Microplastics in facial cleansers 总被引:6,自引:0,他引:6
Lisa S. Fendall 《Marine pollution bulletin》2009,58(8):1225-9179
Plastics pollution in the ocean is an area of growing concern, with research efforts focusing on both the macroplastic (>5 mm) and microplastic (<5 mm) fractions. In the 1990s it was recognized that a minor source of microplastic pollution was derived from liquid hand-cleansers that would have been rarely used by the average consumer. In 2009, however, the average consumer is likely to be using microplastic-containing products on a daily basis, as the majority of facial cleansers now contain polyethylene microplastics which are not captured by wastewater plants and will enter the oceans. Four microplastic-containing facial cleansers available in New Zealand supermarkets were used to quantify the size of the polythelene fragments. Three-quarters of the brands had a modal size of <100 microns and could be immediately ingested by planktonic organisms at the base of the food chain. Over time the microplastics will be subject to UV-degradation and absorb hydrophobic materials such as PCBs, making them smaller and more toxic in the long-term. Marine scientists need to educate the public to the dangers of using products that pose an immediate and long-term threat to the health of the oceans and the food we eat. 相似文献
56.
在阐述膨润土的矿物学特性、类型及其改性方法(包括酸活化、焙烧、无机盐,有机铵盐)的基础上,探讨了其在废水处理、垃圾填埋场和土壤改良中的应用现状,并以膨润土作为反应介质,COD(化学需氧量)、Cr6+和NH4+为靶污染物,进行垃圾渗滤液对地下水污染的渗透反应格栅(PRB)实验研究,结果表明:pH值和DO(垃圾渗滤液中的溶解氧)对靶污染物的去除效果有一定的影响,且反应介质对COD、Cr6+和NH4+的去除率分别为53%、51%和53%,此结果说明了以膨润土作为PRB的反应介质是可行的. 相似文献
57.
Natural and Enhanced Concentrations of Trace Metals in Sediments of Cleveland Bay, Great Barrier Reef Lagoon, Australia 总被引:1,自引:0,他引:1
Natural variation in concentrations of Cd, Co, Cu, Ni, Pb, and Zn in sediments of Cleveland Bay can be modelled by linear regression by using the concentration of Al recovered by strong acid digestion as an independent variable. Samples that exceed the upper 95% prediction interval of regression models are classified as enhanced. Enhancement of trace metals occurs in the intertidal zone and near-shore sediments of western Cleveland Bay, in sites that are characterized by high accumulation rates of fine grained terrigenous sediment. There is a strong positive relationship between increasing enhancement of Cu and Pb and the recovery of these metals by weak HCl digestion, which suggests that for these metals the modelled enhancement is environmentally meaningful. In contrast, at least 60%, and generally greater than 80% of Cd is recovered by weak HCl digestion irrespective of modelled enhancement, and suggests that the statistically modelled enhancement of Cd may be more meaningful than weak HCl soluble concentrations. 相似文献
58.
59.
A large number of nesting loggerhead sea turtles (n = 201) were sampled to establish the blood levels of 11 elements (Cu, Mn, Pb, Zn, Cd, Ni, Cr, As, Al, Hg, and Se). Almost all of the samples showed detectable levels of these 11 elements, and Zn and Se exhibited the highest concentrations (median values as high as 6.05 and 2.28 μg/g, respectively). The median concentrations of the most toxic compounds, As, Cd, Pb, and Hg, were relatively low (0.38, 0.24, 0.06, and 0.03 μg/g, respectively). We also determined the haematological and biochemical parameters in a subsample of 50 turtles to evaluate the potential effects of these contaminants on clinical parameters and found several associations. Our study reinforces the usefulness of blood for the monitoring of the levels of contaminating elements and their adverse effects on blood parameters in sea turtles. 相似文献
60.