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1.
Potential for Solute Retardation on Monitoring Well Sand Packs and Its Effect on Purging Requirements for Ground Water Sampling 总被引：1，自引：0，他引：1
Monitoring well sand packs are theoretically capable of retarding metal ions and organic contaminants. If this retardation does indeed occur it may have a significant effect on the purging requirements of newly installed monitoring wells. Calculations based on mass balance and retardation concepts demonstrate that if common guidelines for well purging are followed, contaminants may not be detected or may be detected in lower concentrations than are actually present in the ground water. This problem is greatest in relatively shallow wells installed in low to moderate permeability materials. In most cases, the effect of solute retardation in the sand pack can be avoided simply by additional purging prior to the first sampling of the monitoring well. Common purging guidelines can then be applied to subsequent samplings. The methodology outlined in this paper can be used to calculate the purging requirements of existing monitoring wells or it may be applied to alternative monitoring well designs to test which will require the smallest volume of purged water. 相似文献
2.
K. E. Preston D. J. Fish H. K. Roscoe R. L. Jones 《Journal of Atmospheric Chemistry》1998,30(1):163-172
A new method for retrieving the vertical profile of NO2 from ground-based measurements is applied to four months of measurements made at Aberdeen (57°N) during part of SESAME from November 1994 to April 1995. The retrieval method is shown to be an invaluable tool both for deriving the true NO2 vertical column and for removing the tropospheric contribution to the vertical column. This dramatically reduces the effects of tropospheric pollution in the observations and enables a more appropriate comparison with stratospheric 3-D model results. The comparison confirms the accuracy of the model's transport and its reactive nitrogen photochemistry, although there are some detailed discrepancies. 相似文献
3.
Surface and bottom water samples were collected from 39 widely spaced stations in Lake Rotorua in February 1967 and from 12 stations in Lake Rotoiti in March 1967. In Lake Rotorua, data obtained from these samples showed that small horizontal differences existed between the southern and northern parts of the lake probably related to the higher inflow of plant nutrients at the southern end and to the prevailing southerly wind concentrating phytoplankton populations at the northern end. Lake Rotoiti, which differed from Lake Rotorua in being thermally stratified, showed no important horizontal differences, Vigorous mixing in the strata probably being accomplished by deep seiches except in the shallow western basin of the lake, where the inflow from Lake Rotorua occurs. Serial vertical hauls for a zooplankton survey of Lake Rotoiti were taken from three stations in March 1967. The distribution of zooplankton was complex because diurnal vertical migrations of the animals were combined with horizontal movement of the water layers. 相似文献
4.
Gayle Hough Jennifer Green Paul Fish Andy Mills Roger Moore 《Marine Geophysical Researches》2011,32(1-2):151-162
Exploration and development of offshore hydrocarbon resources has advanced into remote deepwater regions over the last decade and poses significant technical challenges for the design and installation of wells and facilities at extreme water depths. Seafloor and shallow subsurface processes and conditions in these areas are complex and generally poorly understood, and the geohazards to development are larger scale and fundamentally different to those encountered onshore; consequently the geohazard risk to deepwater development projects is potentially significant and requires careful evaluation and mitigation during the front-end planning and engineering design stages of projects. There are no established industry standards or methods for the assessment of geohazards and engineering-quality geophysical data at the scale of development. The paper describes an integrated and systematic map-based approach for the assessment and mitigation of seabed geohazards and risk to proposed deepwater development. The approach employs a multi-disciplinary team working with engineering-quality field calibrated data to accurately map and assess seafloor ground conditions and ensure that development proposals are not exposed to intolerable geohazard risk. The approach taken is very similar to the practice of establishing geological models for land-based engineering projects, in which the complete geological history of the site is used to characterise and predict the performance of the ground. Such an approach is routine for major projects on land but so far does not seem to be common practice in the offshore industry. The paper illustrates the seafloor geomophological mapping approach developed. The products are being used to optimise development layouts to avoid geohazards where possible and to support site-specific engineering design of facilities based on a detailed understanding of the potential geohazard loadings and associated risk. 相似文献
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6.
Christoph Zöckler Lera Miles Lucy Fish Annett Wolf Gareth Rees Fiona Danks 《Climatic change》2008,87(1-2):119-130
Climate change is expected to alter the distribution of habitats and thus the distribution of species connected with these
habitats in the terrestrial Barents Sea region. It was hypothesised that wild species connected with the tundra and open-land
biome may be particularly at risk as forest area expands. Fourteen species of birds were identified as useful indicators for
the biodiversity dependent upon this biome. By bringing together species distribution information with the LPJ-GUESS vegetation
model, and with estimates of future wild and domestic reindeer density, potential impacts on these species between the present
time and 2080 were assessed. Over this period there was a net loss of open land within the current breeding range of most
bird species. Grazing reindeer were modelled as increasing the amount of open land retained for nine of the tundra bird species. 相似文献
7.
The distribution and deposits of British and Scandinavian Middle Pleistocene ice sheets in eastern England remain problematic. A new till provenancing technique based on Chalk micropalaeontology is described, with the object of refining understanding of the ice sheet which deposited the Lowestoft Formation till (Anglian/Elsterian) and its relationship to Scandinavian ice sheets. The technique involves extracting foraminifera from Chalk erratics and till matrix obtained from stratigraphically controlled till sections and comparing their micropalaeontology with that of Upper Cretaceous Chalk bedrock. Application to the Lowestoft Formation till of eastern England suggests that current models of ice‐flow in this region require revision involving reinstatement of some earlier ideas. Chalk provenance data indicate an initial phase of glaciation, with ice streaming southwards across eastern England before fanning across East Anglia from the position of the Fen basin. This was followed by a later phase in which the main southward trajectory of ice‐flow was located further east in the North Sea Basin, but again with ice fanning out across East Anglia. These ice‐flow trajectories imply constraint of the British ice sheet by Scandinavian ice. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
8.
江鱼儿 《高原山地气象研究》2000,20(1)
时间:2100年 他们结婚已经3年了. 他很爱她. 她认为他各方面都很好,她很愿意和他一起生活,直到永远.可是每当他们在一起亲热的时候,另一个他的影子就会出现……那是她的初恋情人. 相似文献
9.
Five lakes, varying from 10 to 100 hectares in area and each containing an existing population of Salmo gairdneri, were gill‐netted and stocked with tagged fish each year from 1960 to 1965 to determine the effect of regular stocking on the size and numbers of fish present. There was little natural spawning of trout in most of the lakes. Growth in length and weight of tagged fish was computed and an annual estimate of population calculated from the netting returns. Appendices give details of the statistical analyses of the data. Fish production has been correlated with the trophic status of the lakes as indicated by their temperature and oxygen content. There was no clear relationship between lake size and trout production but trout production decreased as the environment became more eutrophic. Results also showed a close inverse relationship between numbers supported and average weight achieved by the trout. It is concluded that the angling potential of local lakes can be maintained despite the eutrophication resulting from intensive agricultural development of the catchments. These lakes will produce large‐sized fish if the trout population is kept relatively small. Loss in weight in brown and rainbow trout as a result of spawning activities in local lakes and streams was found to be similar. Both male and female fish lost between 22 and 40 percent of their weight over a spawning period. This probably accounted for the observed low‐condition factor among older fish in the lake populations. 相似文献
10.
G. R. Fish 《新西兰海洋与淡水研究杂志》2013,47(4):573-574
Collections of mature medusae from Lake Rotoiti proved all to be male and provide further evidence that the origin of the species in New Zealand was from a very limited introduction. 相似文献