Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for decades.Metabolomics,a functional readout of cellular activity,can capture organismal responses to various contaminant-related stressors,acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants better.This review entails the application of metabolomics to profile metabolic responses of environmental organisms,e.g.animals(rodents,fish,crustacean and earthworms)and microorganisms(bacteria,yeast and microalgae)to different anthropogenic contaminants,including heavy metals,nanomaterials,pesticides,pharmaceutical and personal products,persistent organic pollutants,and assesses their ecotoxicological impacts with regard to literature published in the recent five years.Contaminant-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical organisms.The obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living organisms.Thus with a novel ecotechnique of environmental metabolomics,risk assessments of anthropogenic contaminants are profoundly demonstrated.

Uranium sequestration in sediment at an iron-rich contaminated site at Oak Ridge, Tennessee via.bioreduction followed by reoxidation

This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation.Field tests (1383 days) at Oak Ridge,Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater.Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L.Aliquots of the bioreduced sediment were reoxidized with O2,H2O2,and NaNO3,respectively,over 285 days,resulting in aqueous U of 0.024,1.58 and 14.4 mg/L at pH 6.30,6.63 and 7.62,respectively.The source-and the three reoxidized sediments showed different desorption and adsorption behaviors of U,but all fit a Freundlich model.The adsorption capacities increased sharply at pH 4.5 to 5.5,plateaued at pH 5.5 to 7.0,then decreased sharply as pH increased from 7.0 to 8.0.The O2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0.The NO3--reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0.The pH-dependent adsorption onto Fe(Ⅲ) oxides and formation of U coated particles and precipitates resulted in U sequestration,and bioreduction followed by reoxidation can enhance the U sequestration in sediment.

Sustainable treatment of nitrate-containing wastewater by an autotrophic hydrogen-oxidizing bacterium

Bacteria are key denitrifiers in the reduction of nitrate(NO_(3)^(-)N),which is a contaminant in wastewater treatment plants(WWTPs).They can also produce carbon dioxide(CO_(2))and nitrous oxide(N2O).In this study,the autotrophic hydrogen-oxidizing bacterium Rhodoblastus sp.TH_(2)0 was isolated for sustainable treatment of NO_(3)^(-)N in wastewater.Efficient removal of NO_(3)^(-)N and recovery of biomass nitrogen were achieved.Up to 99%of NO_(3)^(-)N was removed without accumulation of nitrite and N2O,consuming CO_(2)of 3.25 mol for each mole of NO_(3)^(-)N removed.The overall removal rate of NO_(3)^(-)N reached 1.1 mg L^(-1)h^(-1)with a biomass content of approximately 0.71 g L^(-1)within 72 h.TH20 participated in NO_(3)^(-)N assimilation and aerobic denitrification.Results from 15N-labeled-nitrate test indicated that removed NO_(3)^(-)N was assimilated into organic nitrogen,showing an assimilation efficiency of 58%.Seventeen amino acids were detected,accounting for 43%of the biomass.Nitrogen loss through aerobic denitrification was only approximately 42%of total nitrogen.This study suggests that TH_(2)0 can be applied in WWTP facilities for water purification and production of valuable biomass to mitigate CO_(2)and N_(2)O emissions。