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81.
In this study the preparation of filter aid from filter cake is considered. Two methods of preparation, carbonization at 550–600 °C and combustion at 800–1000 °C, are used and the optimum conditions determined. The performance of the products is assessed as both a precoat and body feed by comparison with a commercial grade of diatomite. It is shown that efficient filter aids, with performances comparable to that of diatomite, may be produced from filter cake. 相似文献
82.
Effect of green manure and supplemental fertility amendments on selected soil quality parameters in an organic potato rotation in Eastern Canada 总被引:1,自引:0,他引:1
Mehdi Sharifi Derek H. Lynch Andrew Hammermeister David L. Burton Aime J. Messiga 《Nutrient Cycling in Agroecosystems》2014,100(2):135-146
The effects of green manure, crop sequence and off-farm composts on selected soil quality parameters were assessed in a three-year organic potato (Solanum tuberosum L.) rotation in Eastern Canada. Three crop sequences varying in preceding green manure [red clover (RCl) + RCl, and beans/buckwheat or carrots + oats/peas/vetch mixture (OPV)] as main plots and four fertility treatments applied in the potato phase only [control; inorganic fertilizer; municipal solid waste compost (MSW); composted paper mill biosolid (PMB)] as subplots were compared. In 2008 and 2010, changes in selected soil quality parameters (0–15 cm) were assessed prior to planting of potatoes and at potato tuber initiation stage. Potentially mineralizable nitrogen (N) and the acid phosphatase enzyme activity average values across years were greater following RCl (1.51 abs and 622 kg ha?1) compared with OPV (1.32 abs and 414 kg ha?1) at potato planting. Soil NO3–N average value was greater following RCl compared with OPV (63 vs. 52 kg ha?1) at tuber initiation. For the other measured parameters, OPV and RCl were similar. The soil organic carbon (C) and particulate organic matter-C were greater under PMB and MSW (31.1 and 7.57 kg ha?1) compared with fertilizer treatment (27.9 and 6.05 kg ha?1). The microbial biomass C and microbial biomass quotient were greater under MSW (216 kg ha?1 and 0.73 %) than PMB and fertilizer (147 kg ha?1 and 0.50 %) across crop rotations. Annual legume green manures and off-farm composts can be used to satisfy potato N requirement and maintains soil quality in organic potato rotations. 相似文献
83.
Chlorobenzenes, chlorinated pesticides, coplanar chlorobiphenyls and other organochlorine compounds in Greenland biota 总被引:9,自引:0,他引:9
Vorkamp K Riget F Glasius M Pécseli M Lebeuf M Muir D 《The Science of the total environment》2004,331(1-3):157-175
This paper summarises the levels and composition of chlorobenzenes, chlorinated pesticides, coplanar polychlorinated biphenyls (PCBs) and the chlorinated compounds octachlorostyrene (OCS), hexachlorocyclobutadiene (HCBD) and pentachloro-anisole (PCA) in biota from the terrestrial, freshwater and marine environment of Greenland. The data were obtained during the second phase of the Arctic Monitoring and Assessment Programme (AMAP). Of the chlorobenzenes, hexachlorobenzene was the main constituent detected in almost all samples. The chlorobenzenes accumulate in the marine food web in a similar manner to the better-studied persistent organic pollutants, with maximum concentrations in beluga, minke whale and narwhal. However, concentrations in ringed seals and kittiwakes were lower than in marine fish, contradicting biomagnification. Of the organochlorine pesticides, the drin pesticides (aldrin, endrin, dieldrin) and heptachlor had increasing concentrations along the food chain, whilst biomagnification was less pronounced for endosulfan, methoxychlor and mirex. Endosulfan and methoxychlor are pesticides still in use and considered less persistent than other organochlorine pesticides. Their occurrence in Arctic biota is of particular concern, also given the high acute toxicity of endosulfan to fish. Chlorobenzene and pesticide concentrations tended to be lower in the Greenland samples than in the same animals from the Canadian Arctic, whilst their concentrations were similar to samples from Svalbard and Iceland. However, temporal trends might overlap the geographical differences. Coplanar chlorobiphenyls (CBs) were found in all samples analysed, with the maximum concentrations found in marine mammals such as beluga and narwhal. Biota from the terrestrial environment appeared to be less contaminated. The main contributor on a TEQ basis was CB126. OCS, HCBD and PCA were detected in biota from Greenland, although at very low concentrations. OCS seems to have the widest occurrence and the highest potential for biomagnification of the three compounds analysed. 相似文献
84.
Biofilm in the sediment phase of a sanitary gravity sewer 总被引:4,自引:0,他引:4
Microbial activity of the sediment phase in a 1.5-km-long concrete sewer section with a cement pipe in a 540-mm diameter was investigated in this paper. SEM examinations and elementary composition analyses of the sediment samples have identified the presence of a biofilm layer at the sediment surface. Bacterial counting results with a DNA-staining technique have revealed that the amount of bacteria in this layer was 2.1 x 10(11)cellg(-1) dry wt, which is close to that of activated sludge. ATP content in the sewer biofilm was found relatively high, demonstrating that the sewer biofilm is active. Throughout the entire 1.5-km sewer section, the biofilm activity was maintained at almost the same level. Lab-scale sediment oxygen uptake flux (SOUF) tests showed that the shear flow velocity above the sediment phase linearly increases the SOUF, which of the potential value was determined to be 32gO(2)m(-2) day(-1) at an estimated shear flow velocity of 0.055ms(-1) at 25 degrees C in the sewer line, provided that the mean flow velocity was 1.5ms(-1), and the mean water depth was 220mm. Such a high SOUF value further endorsed the existence of the active sewer biofilm. 相似文献
85.
86.
Lisa Hoferkamp Mark H. Hermanson Derek C.G. Muir 《The Science of the total environment》2010,408(15):2985-267
This review will summarize the levels of selected current use pesticides (CUPs) that have been identified and reported in Arctic media (i.e. air, water, sediment, and biota) since the year 2000. Almost all of the 10 CUPs (chlorothalonil, chlorpyrifos, dacthal, diazinon, dicofol, lindane, methoxychlor, pentachloronitrobenzene (PCNB), pentachlorophenol, and trifluralin) examined in the review currently are, or have been, high production volume chemicals i.e. > 1 M lbs/y in USA or > 1000 t/y globally. Characteristic travel distances for the 10 chemicals range from 55 km (methoxychlor) to 12,100 km (PCNB). Surveys and long-term monitoring studies have demonstrated the presence of 9 of the 10 CUPs included in this review in the Arctic environment. Only dicofol has not been reported. The presence of these chemicals has mainly been reported in high volume air samples and in snow from Arctic ice caps and lake catchments. There are many other CUPs registered for use which have not been determined in Arctic environments. The discovery of the CUPs currently measured in the Arctic has been mainly serendipitous, a result of analyzing some samples using the same suite of analytes as used for studies in mid-latitude locations. A more systematic approach is needed to assess whether other CUPs might be accumulating in the arctic and ultimately to assess whether their presence has any significance biologically or results in risks for human consumers. 相似文献
87.
88.
89.
A number of computational models have been developed over the last 2 decades that are remarkably successful at explaining the process of translating print into sound. Nevertheless, 2 of the most successful computational accounts on the table fail to simulate the results from factorial experiments reported in this article in which university students read aloud letter strings that varied in terms of spelling–sound regularity and lexicality (regular words vs. exception words vs. nonwords) and stimulus quality (bright vs. dim). Skilled readers yielded additive effects of regularity and stimulus quality and additive effects of lexicality and stimulus quality on both RT and errors when nonwords were mixed with words. When only words appeared in the list, there was an interaction in which exception words were less affected by low stimulus quality than regular words were; no existing account anticipates or explains these results. We advance a hypothesis that assumes a novel module that accommodates these data and provide an existence proof in the form of a simulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
90.
Christopher J. Shepherd Gareth J. Appleby-Thomas James M. Wilgeroth Paul J. Hazell Derek F. Allsop 《International Journal of Impact Engineering》2011,38(12):981-988
The effects of projectile penetration into soft tissue are often studied using the tissue simulant ballistic soap. Consequently, a full understanding of the high strain-rate response of ballistic soap is desirable. Using the plate-impact technique, key shock parameters have been measured for impacts in the range 81–968 m/s, allowing derivation of the Hugoniot equation-of-state for soap in the US–uP and σX–uP planes. A polynomial Hugoniot relationship was found in the US–uP plane, with the general form US = 1.96 + 2.41uP − 0.72uP2 (ρ0 = 1.107 g/cc). Further, embedded lateral manganin stress gauges were employed to interrogate the evolution of lateral stress within the soap. A gradient in lateral stress, whose magnitude increased incrementally with impact stress, was apparent behind the shock for σX >1 GPa. It is proposed that at higher values of σX, increased compression of hydrocarbon chains acts to increase the materials resistance to shear, a phenomenon consistent with steric hindrance. 相似文献