Hazardous Waste Pollution Prevention Using Clay with Admixtures     

Papita Saha  Siddhartha Datta  Shyamal Kanti Sanyal 《洁净——土壤、空气、水》2008,36(2):230-238

Landfill is the most commonly used method for disposal of waste materials since it is one of the least expensive methods. In order to dispose of any hazardous material to a landfill, a liner is used, which protects the underlying land and groundwater since it acts as a barrier to fluid movement. Of the various methods available for providing improved and more effective properties of landfills, methods involving the use of bentonite, cement, lime, gypsum, etc., have been explored in the laboratory. The aim is to overcome the problem and deficiencies of the existing liners. It is observed from the experimental results that the metal concentrations of the input waste solution can be reduced to 80–98% using a soil‐cement admixture, 60–95% using a soil‐gypsum mixture, 45–95% using a soil‐bentonite mixture, 50–90% for soil, 35–80% using a soil‐lime mixture, as liner materials. The permeation rate of different metals through the different soil‐admixture media depends on various factors. A simple mathematical treatment of the phenomenon related to the permeation of liquid through the admixture of the clay and other components has been developed. The experimental results show satisfactory agreement with the predictions.  相似文献   

Structural Studies of a UDP-glucuronosyltransferase gene from the plaice (Pleuronectes platessa)     

Stephen G. George  Michael J. Leaver  Joy Wright 《Marine environmental research》1998,46(1-5)

A partial length cDNA coding for the putative PAH-inducible phenol-conjugating UDP-glucururonosyltransferases (UGT) isoform of plaice was used to isolate overlapping clones from a plaice genomic library. Sequence analysis revealed the presence of a complete gene spanning 4.1 kb for a plaice UGT which showed a strong conservation in exon structure, amino acid character and amino acid sequence with mammalian UGT1 family genes, although additional alternative upstream exon 1s were not identified in the present study. Southern blot analysis revealed a low copy number for the gene and some degree of structural polymorphism in gene structure between individuals. This was also reflected in the finding that there were significant variations between the nucleotide sequences of the plaice gene and the cDNA previously isolated from a different individual fish. Future studies will investigate the possibility that there may be phenotypic variations which could lead to alterations in susceptibility to pollutant toxicity.  相似文献   

Fish assemblage composition in constructed and natural tidal marshes of San Diego Bay: Relative influence of channel morphology and restoration history     

Gregory D. Williams  Joy B. Zedler 《Estuaries and Coasts》1999,22(3):702-716

This study evaluated the use by fish of restored tidal wetlands and identified links between fish species composition and habitat characteristics. We compared the attributes of natural and constructed channel habitats in Sweetwater Marsh National Wildlife Refuge, San Diego Bay, California, by using fish monitoring data to explore the relationships between channel environmental characteristics and fish species composition. Fishes were sampled annually for 8 yr (1989–1996) at eight sampling sites, four in constructed marshes and four in natural marshes, using beach seines and blocking nets. We also measured channel habitat characteristics, including channel hydrology (stream order), width and maximum depth, bank slope, water quality (DO, temperature, salinity), and sediment composition. Fish colonization was rapid in constructed channels, and there was no obvious relationship between channel age and species richness or density. Total richness and total density did not differ significantly between constructed and natural channels, although California killifish (Fundulus parvipinnis) were found in significantly higher densities in constructed channels. Multivariate analyses showed fish assemblage composition was related to channel habitat characteristics, suggesting a channel’s physical properties were more important in determining fish use than its restoration status. This relationship highlights the importance of designing restoration projects with natural hydrologic features and choosing proper assessment criteria in order to avoid misleading interpretations of constructed channel success. We recommend that future projects be designed to mimic natural marsh hydrogeomorphology and diversity more closely, the assessment process utilize better estimates of fish habitat function (e.g., individual and community-based species trends, residence time, feeding, growth) and reference site choice, and experimental research be further incorporated into the restoration process.  相似文献   

A review of radio observations of planetary nebulae     

Joy Heckathorn 《Astrophysics and Space Science》1971,11(2):309-321

The observational data for planetary nebulae in the radio region of the spectrum is reviewed and summarized. The methods of determining interstellar extinction, electron temperatures and turnover points in the spectrum from these observations are given, as are the tests for the recombination theory and a discussion of the validity of several models of these objects.  相似文献   

Determination of Iodine in Thirty Two International Geochemical Reference Materials     

Joy E. Rae  Salim A. Malik 《Geostandards and Geoanalytical Research》1998,22(2):199-201

Thirty two geochemical reference samples have been analysed for their iodine contents by a pyrohydrolysis extraction technique, followed by colourimetry. In spite of the existence of few reported values for iodine, limiting comparison with results from this study, the four available "reference" values show good agreement with the work reported here.  相似文献   

Late Quaternary highstands at Lake Chilwa,Malawi: Frequency,timing and possible forcing mechanisms in the last 44 ka     

David S.G. Thomas  Richard Bailey  Paul A. Shaw  Julie A. Durcan  Joy S. Singarayer 《Quaternary Science Reviews》2009,28(5-6):526-539

The extensive shoreline deposits of Lake Chilwa, southern Malawi, a shallow water body today covering 600 km² of a basin of 7500 km², are investigated for their record of late Quaternary highstands. OSL dating, applied to 36 samples from five sediment cores from the northern and western marginal sand ridges, reveal a highstand record spanning 44 ka. Using two different grouping methods, highstand phases are identified at 43.7–33.3 ka, 26.2–21.0 ka and 17.9–12.0 ka (total error method) or 38.4–35.5 ka, 24.3–22.3 ka, 16.2–15.1 ka and 13.5–12.7 ka (Finite Mixture Model age components) with two further discrete events recorded at 11.01 ± 0.76 ka and 8.52 ± 0.56 ka. Highstands are comparable to the timing of wet phases from other basins in East and southern Africa, demonstrating wet conditions in the region before the LGM, which was dry, and a wet Lateglacial, which commenced earlier in the southern compared to northern hemisphere in East Africa. We find no evidence that wet phases are insolation driven, but analysis of the dataset and GCM modelling experiments suggest that Heinrich events may be associated with enhanced monsoon activity in East Africa in both timing and as a possible causal mechanism.  相似文献   

<Emphasis Type="Italic">Conjunto</Emphasis> culture: celebration and racialization in the German-Texan “Borderlands”     

Joy K. Adams 《GeoJournal》2010,75(3):303-314

Sustained migration of Hispanics and Anglos into Texas’s historical “German belt” has contributed to a significant decline in the proportion of Central Texans claiming German ancestry. Under these circumstances, ethnic festivals are playing an increasingly important role in maintaining the German-American identity of many of the region’s people and places. Organizers and participants frequently tout the events’ inclusiveness, claiming that anyone can temporarily cross ethnic boundaries to become “German for a day” within the festival context. However, participant observation and surveys of festival participants in three historically German-American communities (Brenham, Fredericksburg, and New Braunfels) suggest that ethnic-themed events mirror processes of racialization that have persisted in the region for more than 150 years. In this paper, I argue that, in helping to construct “German” identities for the region’s people and places, German-themed events in Central Texas are implicitly involved in the construction of “non-German” and, by extension “non-white,” ethnic identities. Further, event participation patterns reflect a long-standing black-white racial dichotomy in the region. Within this ethnoracial hierarchy, Hispanics have long occupied a liminal status that is reflected by their involvement in the production and consumption of German-themed events. I contend that Hispanics’ participation in German heritage festivals reflects not only a historical process of “whitening” their racial status but their increasing presence and power within the region.  相似文献   

Basaltic diversity at the Apollo 12 landing site: Inferences from petrologic examinations of the soil sample 12003     

Joshua F. Snape  Katherine H. Joy  Ian A. Crawford  Louise Alexander 《Meteoritics & planetary science》2014,49(5):842-871

A detailed petrologic survey has been made of 17 basaltic chips (sized between 1 and 10 mm) from the 12003 soil sample as part of an ongoing study of basaltic diversity at the Apollo 12 landing site. An attempt has been made to classify these samples according to the well‐established grouping of olivine, pigeonite, ilmenite, and feldspathic basalts. Particular attention has been paid to variations in major, minor, and trace element mineral chemistry (determined by electron microprobe analysis and laser ablation ICP‐MS), which may be indicative of particular basaltic suites and less susceptible to sampling bias than bulk sample characteristics. Examples of all three main (olivine, pigeonite, and ilmenite) basaltic suites have been identified within the 12003 soil. One sample is identified as a possible new addition to the feldspathic suite, which currently consists of only one other confirmed sample. Identification of additional feldspathic basalts strengthens the argument that they represent a poorly sampled basaltic flow local to the Apollo 12 site, rather than exotic material introduced to the site by impact mixing processes. Three samples are identified as representing members of one or two previously unrecognized basaltic suites.  相似文献   

An unusual clast in lunar meteorite MacAlpine Hills 88105: A unique lunar sample or projectile debris?     

K. H. Joy  I. A. Crawford  G. R. Huss  K. Nagashima  G. J. Taylor 《Meteoritics & planetary science》2014,49(4):677-695

Lunar meteorite MacAlpine Hills (MAC) 88105 is a well‐studied feldspathic regolith breccia dominated by rock and mineral fragments from the lunar highlands. Thin section MAC 88105,159 contains a small rock fragment, 400 × 350 μm in size, which is compositionally anomalous compared with other MAC 88105 lithic components. The clast is composed of olivine and plagioclase with minor pyroxene and interstitial devitrified glass component. It is magnesian, akin to samples in the lunar High Mg‐Suite, and also alkali‐rich, akin to samples in the lunar High Alkali Suite. It could represent a small fragment of late‐stage interstitial melt from an Mg‐Suite parent lithology. However, olivine and pyroxene in the clast have Fe/Mn ratios and minor element concentrations that are different from known types of lunar lithologies. As Fe/Mn ratios are notably indicative of planetary origin, the clast could either (1) have a unique lunar magmatic source, or (2) have a nonlunar origin (i.e., consist of achondritic meteorite debris that survived delivery to the lunar surface). Both hypotheses are considered and discussed.  相似文献   

Ages of Globally Distributed Lunar Paleoregoliths and Soils from 3.9 Ga to the Present     

Amy L. Fagan  Katherine H. Joy  Donald D. Bogard  David A. Kring 《Earth, Moon, and Planets》2014,112(1-4):59-71

This study determines the ages of 191 discrete lunar regolith samples from the Apollo, Luna, and meteorite collections. Model closure ages (for lithified breccias) and appearance ages (for unconsolidated soils) are calculated using the trapped ⁴⁰Ar and ³⁶Ar abundances of each sample, determined from published Ar data. Model closure ages of regolith breccias span ~3.9 to 0.01 Ga and appearance ages of soils range from ~3.6 to 0.03 Ga; 169 of these ages are published here for the first time, while 22 are recalculated ages. The regolith breccias with the oldest closure ages originate from the ancient highlands and oldest mare surfaces sampled by the Apollo missions. Soils generally have similar ages to each other, regardless of location and collection depth, with most model ages <2.0 Ga. Together, the soils and regolith breccias represent a record of regolith processes over the past 3.9 Ga. The data illustrate that individual landing sites can provide a diversity of ages, which has implications for planning future missions. Differences in maturity between older and younger regolith samples may reflect a change in collisional regimes over time. We note, too, that the closure ages published here are critical data needed for selecting temporally appropriate regolith samples used to decipher the diversity of impactors hitting the lunar surface over time and how the Sun has changed in time.  相似文献