Project description:Little progress has been made in studying the toxicity of realistic 'non-pristine' forms of nanoparticles that presents in real soil environment. It is presently unkown whether the transformed nanoparticles in realistic environment exerts an adverse effect to rhizobium-legume symbiosis on molecular level. We used microarray to investigate the toxicogenomic responses of the model legume Medicago truncatula following 30 days exposure to three different types of biosolids (control biosolids (control BS), a mixture of Ag, ZnO and TiO2 manufactured nanomaterials added biosolids (Nano BS) and a corresponding bulk metals added biosolids (Bulk BS) ) amended soil that were aged for 6 months prior to exposure in pot experiment.
Project description:Little progress has been made in studying the toxicity of realistic 'non-pristine' forms of nanoparticles that presents in real soil environment. It is presently unkown whether the transformed nanoparticles in realistic environment exerts an adverse effect to rhizobium-legume symbiosis on molecular level. We used microarray to investigate the toxicogenomic responses of the model legume Medicago truncatula following 30 days exposure to three different types of biosolids (control biosolids (control BS), a mixture of Ag, ZnO and TiO2 manufactured nanomaterials added biosolids (Nano BS) and a corresponding bulk metals added biosolids (Bulk BS) ) amended soil that were aged for 6 months prior to exposure in pot experiment. Our Genechip® Medicago Genome Array is designed specially to monitor gene expression in Medicago truncatula, Medicago sativa, and the symbiotic organism Sinorhizobium meliloti. For our study, RNA were extracted from shoots and roots of Medicago truncatula that exposure to control, Bulk and Nano BS treatments for 30 days, and used for all hybridization on Affymetrix microarray. The objective of our study is to investigate the molecular mechanisms of toxicity of Nano BS in comparison with their counterpart Bulk BS treatment, using a commercial Medicago truncatula microarrays.
Project description:This contribution describes the application of an emergy-based methodology for comparing two management alternatives of biosolids produced in a wastewater treatment plant. The current management practice of using biosolids as soil fertilizers was evaluated and compared to another alternative, the recovery of energy from the biosolid gasification process. This emergy assessment and comparison approach identifies more sustainable processes which achieve economic and social benefits with a minimal environmental impact. In addition, emergy-based sustainability indicators and the GREENSCOPE methodology were used to compare the two biosolid management alternatives. According to the sustainability assessment results, the energy production from biosolid gasification is energetically profitable, economically viable, and environmentally suitable. Furthermore, it was found that the current use of biosolids as soil fertilizer does not generate any considerable environmental stress, has the potential to achieve more economic benefits, and a post-processing of biosolids prior to its use as soil fertilizer improves its sustainability performance. In conclusion, this emergy analysis provides a sustainability assessment of both alternatives of biosolid management and helps decision-makers to identify opportunities for improvement during the current process of biosolid management.
Project description:Reuse of wastewater effluent and biosolids in agriculture is essential to sustainable water and nutrient resource management practices. Wastewater and biosolids, however, are reportedly the recipients, reservoirs, and sources of antibiotic-resistant enteric pathogens. While decay rates of fecal bacterial indicators in soil are frequently studied, very few studies have reported on the persistence of the antibiotic-resistant sub-populations. Little is known about how multi-drug resistance phenotypes of enteric bacteria in agricultural soil change over time. In this study, germinated carrot seeds were planted in soil that received biosolids amendment and/or wastewater effluent irrigation in a greenhouse setting. We quantified total and antibiotic-resistant fecal bacterial indicators (Escherichia coli and enterococci) weekly in soil and total E. coli at harvest (day 77) on carrots. Antibiotic susceptibility of 121 E. coli and 110 enterococci collected isolates were determined. E. coli or enterococci were not recovered from the soil without biosolids amendment regardless of the irrigation water source. After biosolids amendment, soil E. coli and enterococci concentrations increased more than 3 log10 CFU/g-TS within the first week, declined slowly over time, but stayed above the detection limit (0.39 CFU/g-TS) over the entirety of the study. No statistical difference was found between effluent wastewater or water irrigation in soil total and antibiotic-resistant E. coli and enterococci concentrations or carrots E. coli levels. Soil antibiotic-resistant E. coli and enterococci decayed significantly faster than total E. coli and enterococci. Moreover, the prevalence of multi-drug resistant (resistance to three or more antibiotics) E. coli declined significantly over time, while almost all collected enterococci isolates showed multi-drug resistance phenotypes. At harvest, E. coli were present on carrots; the majority of which were resistant to ampicillin. The survival of antibiotic-resistant enteric bacteria in soil and on harvested carrots indicates there are transmission risks associated with biosolids amendment use in root crops.