Salinity and Soluble Organic Matter on Virus Sorption in Sand and Soil Columns     

by Haibo Cao  Frank T.-C. Tsai  Kelly A. Rusch 《Ground water》2010,48(1):42-52

The objective of this research was to study the sorption and transport of bacteriophage MS-2 (a bacterial virus) in saturated sediments under the effect of salinity and soluble organic matter (SOM). One-dimensional column experiments were conducted on washed high-purity silica sand and sandy soil. In sand column tests, increasing salinity showed distinct effect on enhancing MS-2 sorption. However, SOM decreased MS-2 sorption. Using a two-site reversible-irreversible sorption model and the double layer theory, we explained that pore-water salinity potentially compressed the theoretical thickness of double layers of MS-2 and sand, and thus increased sorption on reversible sorption sites. On irreversible sorption sites, increasing salinity reversed charges of some sand particles from negative to positive, and thus converted reversible sorption sites into irreversible sites and enhanced sorption of MS-2. SOM was able to expand the double layer thickness on reversible sites and competed with MS-2 for the same binding place on irreversible sites. In sandy soil column tests, the bonded and dissolved (natural) soil organic matters suppressed the effects of pore-water salinity and added SOM and significantly reduced MS-2 adsorption. This was explained that the bonded soil organic matter occupied a great portion of sorption sites and significantly reduced sorption sites for MS-2. In addition, the dissolved soil organic matter potentially expanded the double layer thickness of MS-2 and sandy soil on reversible sorption sites and competed with MS-2 for the same binding place.  相似文献   

Transportation of water,particulate and dissolved organic and inorganic matter between a salt marsh and the Ems-Dollard estuary,The Netherlands     

Norbert Dankers  Michel Binsbergen  Koos Zegers  Remi Laane  Michiel Rutgers van der Loeff 《Estuarine, Coastal and Shelf Science》1984,19(2):143-165

Transport processes were studied in a gully between a salt marsh and an estuary. After storm tides, ebb currents in the gully reached high values. It is concluded that particulate matter (both organic and inorganic) are imported into the marsh. Coarse organic debris is exported during storm tides, but this amount is low when compared with the primary production on the marsh. Exports are shown for dissolved organic carbon, ammonia, phosphate and silica, while nitrate and possibly nitrite are imported. Organic matter derived from in situ production and net import is buried and partly mineralized in the marsh.  相似文献   

Erratum/     

by Mary P. Anderson 《Ground water》2005,43(2):162-162

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Microbiological monitoring and classification of karst springs     

Michael Sinreich  Michiel Pronk  Ronald Kozel 《Environmental Earth Sciences》2014,71(2):563-572

The use of groundwater as a drinking water resource requires knowledge of its microbiological status and quality. In contrast to conventional microbiological monitoring of groundwater, the present study not only considers faecal indicator bacteria, but also covers a wide spectrum of microorganisms, including bacterial pathogens (verotoxin-producing E. coli, Campylobacter spp. and Salmonella spp., as well as Pseudomonas aeruginosa), human enteric viruses (norovirus, enterovirus, rotavirus and adenovirus) and parasitic protozoa (Cryptosporidium oocysts and Giardia cysts). Samples collected at karst sites of the Swiss National Groundwater Monitoring network revealed the presence of a large diversity of microorganisms of faecal origin, the occurrence of which could be linked to specific hydrogeological settings and situations. The findings represent a ‘snapshot’ of the microbiological status at the monitoring sites and provide a national overview of the types and presence of microorganisms in Swiss karst groundwater. In addition to microbiological parameters related to faecal contamination, the overall bacterial load in groundwater was assessed using cell density measurements (i.e. total cell count), which yielded typical ranges for this ecological parameter. The study highlights differential vulnerability of karst groundwater to microbiological contamination, as well as its relationship with the microbial biocenoses, i.e. the interplay of allochthonous and autochthonous microbial components. On the basis of this data set, a microbiological classification of karst aquifers is proposed and discussed with respect to spring dynamics and vulnerability.  相似文献   

Edgar Hynes Thompson: a collection of centenary reminiscences     

Collected  compiled by K. B. Atkinson 《The Photogrammetric Record》2010,25(129):55-68

The idea for this collection of memories of E. H. Thompson began as a suggestion to potential contributors for anything from "a couple of sentences to a couple of paragraphs". Both their willingness to write and the length of some contributions show how influential Thompson has been in the lives of so many of his colleagues and students. Contributors include two past-presidents of the International Society for Photogrammetry and Remote Sensing and six past-presidents of the Photogrammetric Society. Three longer essays are published as separate contributions to this feature.  相似文献   

Normal-branch quasi-periodic oscillations during the high-intensity state of Cygnus X-2     

Rudy Wijnands †  Michiel van der Klis 《Monthly notices of the Royal Astronomical Society》2001,321(3):537-543

Using data obtained with the Rossi X-ray Timing Explorer , we report the detection of a 5-Hz quasi-periodic oscillation (QPO) in the bright low-mass X-ray binary and Z source Cygnus X-2 during high overall intensities (the high-intensity state). This QPO was detected on the so-called normal-branch and can be identified with the normal-branch QPO or NBO. Our detection of the NBO is the first one during times when Cygnus X-2 was in the high-intensity state. The rms amplitude of this QPO decreased from 2.8 per cent between 2 and 3.1 keV to <1.9 per cent between 5.0 and 6.5 keV. Above 6.5 keV, its amplitude rapidly increased to ∼12 per cent rms above 16 keV. The time lags of the QPO were consistent with being zero below 5 keV (compared with the 2–3.1 keV band), but they rapidly increased to ∼70 ms (140°) around 10 keV, above which the time lags remained approximately constant near 70 ms. The photon energy dependences of the rms amplitude and the time lags are very similar to those observed for the NBO with other satellites ( Ginga , EXOSAT ) at different (i.e. lower) intensity states.  相似文献