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Observable differences in particle size, smoothness and compaction between cap site (slope 2·8 per cent) and batter site (slope 20·7 per cent) surfaces on the waste rock dump at Ranger Uranium Mine were quantified in terms of revised universal soil loss equation (RUSLE) parameter values. Cap site surface material had a Km (erodibility corrected for sediment density) of 0·030 and batter site surface material had a Km of 0·0056. Using these Km values (derived from particle size distributions), slope length and steepness (LS) factors of 0·36 for the cap site and 3·66 for the batter site, and a cover (C) factor of 0·45 for the cap site and 0·16 for the batter site, the RUSLE predicts an erosion rate from the cap site that is 1·9 times greater than erosion from the much steeper batter site. The RUSLE indicates that the finer particle size and blocky soil structure of the cap site (D50 = 0·91 mm) compared with the looser granular structure of the batter site (D50 = 1·74 mm) strongly influence erosion. The predictions are similar to observed soil losses from erosion plots on these sites under rainfall simulation events, for which the measured erosion rate from the cap site was approximately twice that from the batter site. For the RUSLE to predict the observed erosion rates, the support practice (P) factor for the cap site would have to be approximately 30 per cent greater than the P factor for the batter site. The higher cap site P factor probably results from smoothing and compaction caused by vehicle movement across the surface. Compaction is considered to have greatly reduced infiltration capacity, thus increasing the erodibility of the cap site. Vehicles probably also crushed the surface material at the cap site, creating the observed finer particle size distribution and further increasing the erodibility. Compaction, through its effects on erodibility (Km) and surface roughness (P), is concluded to be the major cause of higher erosion from the cap site, even though the slope steepness is 10 times less. Parameterisation of the RUSLE quantifies the differences between sites and explains the unexpected erosion rates observed. The results highlight the need for careful management of rehabilitated sites to avoid increases in erosion which may arise from compaction by machinery. 相似文献
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Accumulation in soil and leaching to groundwater of fentin acetate were studied in the laboratory using two types of Dutch sandy soil differing in organic matter content. Mobility, adsorption, transformation and formation of intermediates were determined in unsaturated soil columns, batch shaking systems and soil incubation systems. Samples were analyzed for monophenyltin, diphenyltin and triphenyltin compounds after methylation. Therefore the transformation products diphenyltin oxide and phenyltin acid were determined separately. Both were detected in soil and pore water. Adsorption indicated that these fungicides are immobile in both types of soil. Nevertheless a small fraction was found in the column leachate. After 1 yr of percolation 5.5 and 20.2% of the dose was recovered as total phenyltin residue in the soil of low and high organic matter content, respectively; all the residue was in the upper 10 cm. The half-life of fentin acetate in soil with 1% organic C varied between 47 and 70 days and between 115 and 140 days in soil with 2% organic C. If fentin acetate is applied annually, one can expect to find an ultimate accumulation level of organotin residues of up to 25% of the annual dose in the plough layer. 相似文献
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M. A. A. Paalman C. H. Van Der Weijden J. P. G. Loch 《Water, air, and soil pollution》1994,73(1):49-60
Sorption of Cd at low concentrations onto river Rhine suspended matter was examined in terms of sorption rate, reversibility and factors such as competition and complexation with major inorganic sea-water ions. More than 90% of the final amount of Cd is sorbed within the first few hours. Desorption experiments show that the process is virtually reversible. In experiments with diluted sea water the sorption of Cd strongly decreases even at low salinity. Sorption isotherms show that the sorption of Cd in NaNO3 solutions is regulated by the free Cd2+ activity. In a Ca(NO3)2 environment the Cd sorption decreases with increasing Ca2+ concentrations, which implies competition between Ca2+ and Cd2+ for the different sorption sites. In different electrolyte solutions of similar ionic strength the sorption of Cd decreases in the solution order NaNO3 > NaCl > NaCl+MgCl2+CaCl2 > diluted sea water. Although inorganic speciation calculations show that even at low salinities dissolved Cd is dominated by Cd-chloro complexes, chloride accounts for only about one third of the increased mobility of Cd. As a result of addition of Ca2+ and Mg2+ the sorption capacity of suspended matter for Cd is further reduced by a factor three. 相似文献
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Jie Ma Timothy J. Bruce Ponnerassery S. Sudheesh Christopher Knupp Thomas P. Loch Mohamed Faisal Kenneth D. Cain 《Journal of fish diseases》2019,42(1):75-84
Bacterial coldwater disease, caused by Flavobacterium psychrophilum, remains one of the most significant bacterial diseases of salmonids worldwide. A previously developed and reported live‐attenuated immersion vaccine (F. psychrophilum; B.17‐ILM) has been shown to confer significant protection to salmonids. To further characterize this vaccine, a series of experiments were carried out to determine the cross‐protective efficacy of this B.17‐ILM vaccine against 9 F. psychrophilum isolates (representing seven sequence types/three clonal complexes as determined by multilocus sequence typing) in comparison with a wild‐type virulent strain, CSF‐259‐93. To assess protection, 28‐day experimental challenges of rainbow trout (Oncorhynchus mykiss) fry were conducted following immersion vaccinations with the B.17‐ILM vaccine. F. psychrophilum strains used in challenge trials were isolated from several fish species across the globe; however, all were found to be virulent in rainbow trout. The B.17‐ILM vaccine provided significant protection against all strains, with relative percent survival values ranging from 51% to 72%. All vaccinated fish developed an adaptive immune response (as measured by F. psychrophilum‐specific antibodies) that increased out to the time of challenge (8 weeks postimmunization). Previous studies have confirmed that antibody plays an important role in protection against F. psychrophilum challenge; therefore, specific antibodies to the B.17‐ILM vaccine strain appear to contribute to the cross‐protection observed to heterologous strain. The ability of such antibodies to bind to similar antigenic regions for all strains was confirmed by western blot analyses. Results presented here support the practical application of this live‐attenuated vaccine, and suggest that it will be efficacious even in aquaculture operations affected by diverse strains of F. psychrophilum. 相似文献
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Timothy J. Bruce Jie Ma Christopher Knupp Thomas P. Loch Mohamed Faisal Kenneth D. Cain 《Journal of fish diseases》2020,43(8):915-928
For salmonid producers, a common threat is Flavobacterium psychrophilum. Recent advancements in bacterial coldwater disease (BCWD) management include the development of a live-attenuated immersion vaccine that cross-protects against an array of F. psychrophilum strains. Emerging family Flavobacteriaceae cases associated with clinical disease have been increasing, including pathogenic isolates of Flavobacterium spp. and Chryseobacterium spp. The cross-protective ability of a live-attenuated F. psychrophilum vaccine was determined against three virulent Flavobacteriaceae isolates. Juvenile rainbow trout were vaccinated, developed high F. psychrophilum-specific antibody titres and were challenged with Chryseobacterium spp. isolates (S25 and T28), a Flavobacterium sp. (S21) isolate, a mixed combination of S21:S25:T28, and a standard virulent F. psychrophilum CSF259-93 strain. Results demonstrated strong protection in the CSF259-93 vaccinated group (relative per cent survival (RPS)=94.44%) when compared to the relevant CSF259-93 controls (p < .001). Protection was also observed for vaccinated fish challenged with the S21:S25:T28 mix (RPS = 85.18%; p < .001). However, protection was not observed with the S21, S25 or T28 isolates alone. Analysis of whole-cell lysates revealed differences in protein banding by SDS-PAGE, but conserved antigenic regions by Western blot in S25 and T28. Results demonstrate that this live-attenuated vaccine provided protection against mixed flavobacterial infection and suggest further benefits against flavobacteriosis. 相似文献
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Isaac Standish Sara Erickson Eric Leis Wes Baumgartner Thomas Loch Christopher Knupp Rebekah McCann Corey Puzach Ryan Katona Ellen Lark Jennifer Bailey Jorge Buening Carey Edwards Kenneth Phillips 《Journal of fish diseases》2020,43(3):305-316
In 2018, Vagococcus salmoninarum was isolated from two lots of broodstock “coaster” brook trout (Salvelinus fontinalis) containing ~1,500 fish at the Iron River National Fish Hatchery, at which time it was identified as the causative agent of a chronic coldwater streptococcosis epizootic. Clinical signs included exophthalmia, lethargy, erratic swimming and loss of equilibrium. Female fish experienced disproportionately higher morbidity and mortality than male co-inhabitants, and routinely retained eggs following spawning. The most consistent gross clinical sign was heart pallor and turbid pericardial effusion. An attempted treatment using florfenicol was ineffective at halting the epizootic, which spanned more than a year and resulted in >50% mortality before remaining fish were culled. As there is no previous documentation of V. salmoninarum at this hatchery or in this species, it is still unclear what circumstances led to this epizootic. The inability to treat this chronic disease led to the loss of valuable broodstock, hampering ongoing fishery conservation efforts in the Great Lakes Basin. 相似文献
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Isaac Standish Eric Leis Sara Erickson Rebekah McCann Corey Puzach Ryan Katona Ellen Lark Jennifer Bailey Eric Kleman Jorge Buening Carey Edwards Thomas Loch Kenneth Phillips 《Journal of fish diseases》2020,43(3):317-325
Vagococcus salmoninarum was identified as the causative agent of a chronic epizootic in broodstock “coaster” brook trout (Salvelinus fontinalis) at the Iron River National Fish Hatchery. The epizootic spanned more than a year, was unresponsive to multiple florfenicol treatments, and resulted in >50% mortality of the affected fish. The decision was made to cull the remaining fish during spawning, which presented an opportunity to more thoroughly examine V. salmoninarum sampling methods, organ tropism and vertical transmission. A newly developed qPCR targeting the pheS gene was used in concert with bacterial culture to show that V. salmoninarum indeed disproportionately affects females and has a tropism for female reproductive tissues. The study demonstrates that some female reproductive tissues (e.g. ovarian fluid, unfertilized eggs) are also an effective option for non-lethal detection. Despite the widespread presence of V. salmoninarum in ovarian fluid and on egg surfaces, we found no evidence of intra-ova transmission. 相似文献