Aim
This study evaluates the effect of surface application of dried Class A biosolids on microbial populations within copper mine tailings.
Methods and Results
Mine tailing sites were established at ...ASARCO Mission Mine close to Sahuarita Arizona. Site 1 (December 1998) was amended with 248 tons ha−1 of Class A biosolids. Sites 2 (December 2000) and 3 (April 2006) were amended with 371 and 270 tons ha−1, respectively. Site D, a neighbouring native desert soil, acted as a control for the evaluation of soil microbial characteristics. Surface amendment of Class A biosolids showed a 4 log10 increase in heterotrophic plate counts (HPCs) compared to unamended tailings, with the increase being maintained for 10‐year period. Microbial activities such as nitrification, sulphur oxidation and dehydrogenase activity were also sustained throughout the study period. 16S rRNA clone libraries obtained from community DNA suggest that mine tailings amended with biosolids achieve diversity and bacterial populations similar to native soil bacterial phyla, 10 years postapplication.
Conclusion
Addition of Class A biosolids to copper mine tailings in the desert south‐west increased soil microbial numbers, activity and diversity relative to unamended mine tailings.
Significance and Impact of the Study
The amended tailings resulted in a functional soil with respect to microbial characteristics, which were sustainable over a 10‐year period enabling the development of appropriate vegetation.
The purpose of this study was to determine the prevalence of antibiotic-resistant bacteria and endotoxin in soil after land application of biosolids. Soil was collected over a 15 month period ...following land application of biosolids, and antibiotic resistance was ascertained using clinically relevant antibiotic concentrations. Ampicillin, cephalothin, ciprofloxacin, and tetracycline resistance were all monitored separately for any changes throughout the 15 month period. Endotoxin soil concentrations were monitored using commercially available endotoxin analysis reagents. Overall, land application of biosolids did not increase the percentage of antibiotic-resistant culturable bacteria above background soil levels. Likewise, land application of biosolids did not significantly increase the concentration of endotoxin in soil. This study determined and established a baseline understanding of the overall effect that land application of biosolids had on the land-applied field with respect to antibiotic-resistant bacterial and endotoxin soil densities.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To evaluate the effect of long-term annual land applications of Class B biosolids on soil bacterial diversity at University of Arizona Marana Agricultural Field Center, Tucson, Arizona. Following the ...final of 20 consecutive years of application of Class B biosolids in March 2005, followed by cotton growth from April to November 2005 surface soil samples (0-30 cm) were collected from control (unamended) and biosolid-amended plots. Total bacterial community DNA was extracted, amplified using 16S rRNA primers, cloned, and sequenced. All 16S rRNA sequences were identified by 16S rRNA sequence analysis and comparison to known sequences in GenBank (NCBI B lastN and Ribosomal Database Project II, RDP). Results showed that the number of known genera (identifiable > 96%) increased in the high rate biosolid plots compared to control plots. Biosolids-amended soils had a broad phylogenetic diversity comprising more than four major phyla: Proteobacteria (32%), Acidobacteria (21%), Actinobacteria (16%), Firmicutes (7%), and Bacteroidetes (6%) which were typical to bacterial diversity found in the unamended arid southwestern soils. Bacterial diversity was either enhanced or was not negatively impacted following 20 years of land application of Class B biosolids. This study illustrates that long-term land application of biosolids to arid southwestern desert soils has no deleterious effect on soil microbial diversity.
This study was conducted to determine whether dietary Se deficiency precluded overproduction of glutathione peroxidase-1 (GPX1) activity in mice overexpressing (OE) this gene and thus rescued their ...type 2 diabetes-like phenotypes. A total of 20 male OE and wild-type (WT) mice were fed an Se-deficient (<0.02 mg/kg) diet or an Se-supplemented (0.3 mg/kg as sodium selenite) diet from 1 to 5 mo of age. Dietary Se deficiency eliminated or attenuated (P < 0.05) genotype differences in concentrations of blood glucose, plasma insulin, and/or hepatic lipids, insulin sensitivity, and glucose-stimulated insulin secretion at the end of the study. Dietary Se deficiency decreased (P < 0.05) OE islet mRNA levels of 2 key transcriptional activators (Beta2 and Foxa2) and removed genotype differences in islet mRNA levels of 7 genes (Beta2, Cfos, Foxa2, Pregluc, Ins1, p53, and Sur1) related to insulin synthesis and secretion. Compared with those of the Se-adequate OE mice, the Se-deficient OE mice had lower (P < 0.05) hepatic mRNA levels of 2 key rate-limiting enzymes for lipogenesis (Acc1) and glycolysis (Gk1), along with lower (P < 0.05) activities of hepatic glucokinase and muscle phosphoenolpyruvate carboxykinase. Dietary Se deficiency also decreased (P < 0.05) blood glucose and hepatic lipid concentrations in the WT mice. In conclusion, dietary Se deficiency precluded the overproduction of GPX1 in full-fed OE mice and partially rescued their metabolic syndromes. This alleviation resulted from modulating the expression and/or function of proinsulin genes, lipogenesis rate-limiting enzyme genes, and key glycolysis and gluconeogenesis enzymes in islets, liver, and muscle.
Aims: The purpose of this study was to evaluate the community risk of infection from bioaerosols to residents living near biosolids land application sites.
Methods and Results: Approximately 350 ...aerosol samples from 10 sites located throughout the USA were collected via the use of six SKC Biosamplers®. Downwind aerosol samples from biosolids loading, unloading, land application and background operations were collected from all sites. All samples were analysed for the presence of HPC bacteria, total coliform bacteria, Escherichia coli, Clostridium perfringens, coliphage, enteroviruses, hepatitis A virus and norovirus. Total coliforms, E. coli, C. perfringens and coliphage were not detected with great frequency from any sites, however, biosolids loading operations resulted in the largest concentrations of these aerosolized microbial indicators. Microbial risk analyses were conducted on loading and land application operations and their subsequent residential exposures determined.
Conclusions: The greatest annual risks of infection occurred during loading operations, and resulted in a 4 × 10−4 chance of infection from inhalation of coxsackievirus A21. Land application of biosolids resulted in risks that were <2 × 10−4 from inhalation of coxsackievirus A21. Overall bioaerosol exposure from biosolids operations poses little community risk based on this study.
Significance and Impact of the Study: This study evaluated the overall incidence of aerosolized micro‐organisms from the land application of biosolids and subsequently determined that microbial risks of infection were low for residents close to biosolids application sites.
Soil: A Public Health Threat or Savior? Pepper, I. L.; Gerba, C. P.; Newby, D. T. ...
Critical reviews in environmental science and technology,
05/2009, Letnik:
39, Številka:
5
Journal Article
Recenzirano
Soil is the most complicated biomaterial on the planet due to complex soil architecture and billions of soil microbes with extreme biotic diversity. Soil is potentially a source of human pathogens, ...which can be defined as geo-indigenous, geo-transportable, or geo-treatable. Such pathogens cumulatively can and do result in multiple human fatalities annually. A striking example is Helminths, with current infections worldwide estimated to be around two billion. However, soil can also be a source of antibiotics and other natural products that enhance human health. Soilborne antibiotics are used to treat human infections, but can also result in antibiotic-resistant bacteria. Natural products isolated from soil resulted in 60% of new cancer drugs between the period 1983-1994. Soils are also crucial to human health through their impact on human nutrition. Finally, from a global perspective, soils are vital to the future well-being of nations through their impact on climate change and global warming. A critical review of soil with respect to public health leads to the conclusion that overall soil is a public health savior. The value of soil using a systems approach is estimated to be $20 trillion, and is by far the most valuable ecosystem in the world.
Aim: The purpose of this study was to develop an empirically derived transport model, which could be used to predict downwind concentrations of viruses and bacteria during land application of liquid ...biosolids and subsequently assess microbial risk associated with this practice.
Methods and Results: To develop the model, coliphage MS‐2 and Escherichia coli were aerosolized after addition to water within a biosolids spray application truck, and bioaerosols were collected at discrete downwind distances ranging from 2 to 70 m. Although coliphage were routinely detected, E. coli did not frequently survive aerosolization. Data on aerosolized coliphage was then used to generate a virus transport model. Risks of infection were calculated for various ranges of human virus concentrations that could be found in biosolids.
Conclusions: A conservative estimate at 30·5 m (assumed to be nearest adjacent residences) downwind, resulted in risks of infection of 1 : 100 000, to the more realistic 1 : 10 000 000 per exposure. Conservative annual risks were calculated to be no more than 7 : 100 000 where as a more realistic risk was no greater than 7 : 10 000 000. Overall, the viral risk to residences adjacent to land application sites appears to be low, both for one time and annual probabilities of infection.
Significance and Impact of the Study: This study demonstrated a simple approach towards modelling viral pathogens aerosolized from land applied liquid biosolids, and offers insight into the associated viral risk.
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