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Abstract

Two lysimeter experiments were conducted to evaluate the impacts of biosolids and drinking water treatment residual nanoparticles (nWTRs) on phosphorus and aluminum phytoavailability and yield of corn plants. Two consecutive experiments were conducted with different application rates of biosolids (0% and 3%) and nWTRs (0%, 0.1%, 0.2%, and 0.3%). The results revealed that the total biomass production (grain plus stover) increased significantly (p?<?.05) as a result of nWTRs application at 0.1% rate. Application of nWTRs to biosolids-treated soil slightly decreased yield at 0.2% and 0.3% application rates. The best combination ratio between nWTRs and biosolids at which high corn yield is 0.1% nWTRs to 3% biosolids. Application of 3% biosolids significantly increased bioavailable P in the studied soil, but application of 0.3% nWTRs significantly decreased the bioavailable P concentrations in soil in the two seasons of cultivation. Application of nWTRs at 0.1% and 0.2% rates decreased soil pH in the soil treated with 3% biosolids in first and second seasons of cultivation in comparison with control treatment. The application of nWTRs greatly and significantly (p?<?.05) increased the water-holding capacity of studied soil treated with and without biosolids.  相似文献   
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In 2009, 26 clinical samples (organs and oral/cloacal swabs) from a total of 24 corn snakes (Pantherophis guttatus) from a single owner were sent to our laboratory to be tested for the presence of viruses. Paramyxoviruses (PMV), adenoviruses (AdV) and reoviruses were detected by RT-PCR, PCR and virus isolation methods. Three snakes were infected with all three viruses at the same time, while two other snakes had a double infection (PMV and reo, AdV and reo) and nine other snakes had a single infection with any of the three viruses. No viruses were detected in 10 animals. All isolated reoviruses were identical to one another and to the reptilian orthoreovirus isolate 55-02 in the partial RNA dependent RNA polymerase (RDRP) gene sequence. AdV partial polymerase sequences represented four different types, one of which was first described here: most similar to SnAdV-1, while the other three were identical to known types: SnAV-1, -2 and -3. However, the detected single PMV differed distinctly from described reptile PMV and was a new type. According to partial L gene, HN gene and U gene sequences it may be the first described representative of a third squamatid PMV cluster: "group C" within the proposed reptilian PMV genus "Ferlavirus". Nucleotide identity values for the L gene of the new PMV compared to group A viruses range between 76.5 and 80.3%, and between 80.5 and 81.2% compared to group B viruses. For the HN gene, these values were similar: 78.2-80% (A) and 79.9-80.5% (B) and somewhat lower for the U gene: 72.7-75.4% (A) and 69.7-70% (B). No reports on the prevalence of concurrent viral infection in captive snake populations have been published so far. The possibility of concurrent infection with several different viruses and subsequent consequences for animal health should be kept in mind when testing reptile samples for viruses.  相似文献   
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Purpose

Remobilization of polychlorobiphenyl (PCB)-contaminated sediments by anthropogenic activities (e.g. dredging) or natural flow conditions could lead to the release of PCBs into the water column and consequently increase the availability of PCBs to benthic organisms. The fate of the released PCBs following such events is not well understood and such knowledge is necessary for the management of contaminated sediments. The objective of this study was to understand the processes that control the fate of PCBs following remobilization of field-aged contaminated sediments.

Materials and methods

Sediments contaminated with PCBs collected from Lake Bourget (Savoie, France) were resuspended in a column experiment. The relationships between physical–chemical parameters—i.e. suspended particulate matter, pH, inorganic and organic carbon content, redox-sensitive species and the concentrations of dissolved PCBs both in the water column and in the interstitial water of the sediment—were investigated so as to determine the key processes controlling PCB fate.

Results and discussion

Following the simulated resuspension event (SRE), dissolved PCBs were found in much higher concentrations in the water column than under stationary conditions. Desorption of PCBs from the sediment depended on the degree of the hydrophobicity of the PCBs and the initial PCB content in the sediment. Principal component analysis showed that the variations in the concentrations of released PCBs over time and space closely followed those of suspended particulate matter (SPM) and not those of redox conditions. The partitioning behaviour of PCBs on SPM showed that equilibrium state was not attained within 40 days following the SRE. A particle size fractionation study, before and after remobilization of the sediment, showed the presence of PCBs in every fraction of the sediment, but with higher amounts in large particles with high organic matter content and in the finest fractions. Remobilization of contaminated sediment did not affect this distribution profoundly but a significant enrichment in PCBs of the clay-sized fraction was observed in the re-settled sediment.

Conclusions

Sediment resuspension induced non-equilibrium conditions in the water column for more than 5 weeks and led to the enrichment with PCBs of the newly formed surface bed sediment. This enrichment was due to the preferential re-sorption of PCBs on clay-sized particles during the SRE and to the physical segregation and accumulation of the less dense particles at the surface of the sediment column; such particles thought to be the principal carriers of contaminants. These changes concerned <0.05 % of the total PCB content.  相似文献   
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