Influence of microplastics on the photodegradation of perfluorooctane sulfonamide (FOSA)

PFAS(per-and polyfluoroalkyl substances)are omnipresent in the environment and their transportation and transformation have attracted increased attention.Microplastics are another potential risk substances that can serve as a carrier for ubiquitous pollutants,thus affecting the presence of PFAS in the environment.In this study,the adsorption of perfluorooctane sulfonamide(FOSA)and perfluorooctanoic acid(PFOA)on four microplastics(PE,PVC,PS,and PTFE)and their effect on the photodegradation of FOSA were studied.The adsorption capacity of FOSA by PS was the highest,in similar,PS displayed the highest adsorption capacity in the presence of PFOA.Different effects of pH and salinity on the adsorption of FOSA and PFOA were observed among different microplastics indicating inconsistent interaction mechanisms.Furthermore,FOSA could be photodegraded,with PFOA as the main product,while the presence of microplastics had a negligible effect on the degradation of this contaminant.The results indicated that microplastics could act as PFAS concentrators.Moreover,their photochemical inertiasmake the pollutants enriched onmicroplastics more resistant to degradation.

Levels,distributions,and sources of legacy and novel per-and perfluoroalkyl substances(PFAS)in the topsoil of Tianjin,China

Soil is a major sink for per-and perfluoroalkyl substances(PFAS),wherein PFAS may be transferred through the food chain to predators at upper trophic levels,which poses a threat to human health.Herein,the concentrations and distributions of legacy and novel PFAS in topsoil samples from different functional areas in Tianjin were comprehensively investigated.Seventeen PFAS congeners were identified,with concentrations ranging from 0.21 ng/g to 5.35 ng/g,with a mean concentration of 1.25 ng/g.The main PFAS in the topsoil was perfluorooctanoic acid(PFOA).6:2 chlorinated polyfluorinated ether sulfonate(6:2 ClPFESA;<MDL–1.95 ng/g,mean 0.11 ng/g),as an emerging substitute for perfluorooctane sulfonate(PFOS),was also detected in the topsoil.It showed slightly higher concentrations than PFOS(<MDL–1.62 ng/g,mean 0.10 ng/g),indicating it has gradually replaced legacy PFOS in this area.Based on the positive-definite matrix factor(PMF)receptor model,the major PFAS sources was dominated by textile treatment,metal electroplating plants,and some potential precursors of PFAS with longer chains(>C8)were the major sources(43.4%),followed by food packaging as well as coating materials(25.5%).In addition,Spearman correlation analysis and the structural equation model showed that population density significantly impacted the PFAS distribution in the topsoil of Tianjin.

Molecular characterization of root exudates using Fourier transform ion cyclotron resonance mass spectrometry

The release of root exudates(REs) provides an important source of soil organic carbon. This work revealed the molecular composition of REs of different plant species including alfalfa( Medicago sativa L.), bean( Phaseolus vulgaris L.), barley( Hordeum vulgare L.), maize( Zea mays), wheat( Triticum aestivum L.), ryegrass( Lolium perenne L.) and pumpkin( Cucurbita maxima) using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS). The combination of positive ion mode( + ESI) and negative ion mode(-ESI) increased the number of the molecules detected by ESI FT-ICR MS, and a total of 8758 molecules were identified across all the samples. In detail, lipids and proteins and unsaturated hydrocarbons were more easily detected in + ESI mode, while aromatic compounds with high O/C were readily ionized in-ESI mode, and only 38% of the total assigned formulas were shared by -ESI and + ESI modes. Multivariate statistical analysis of the formulas indicated that the close related plants species secreted REs with similar molecular components. Moreover, the unsaturation degree and nitrogen content were the two key parameters able to distinguish the similarities and differences of molecular components of REs between plant species. The results provided a feasible analysis method for characterization of the molecular components of REs and for the first time characterized the molecular components of REs of a variety of plant species using ESI FT-ICR MS.

Selected dark sides of biomass-derived biochars as environmental amendments

With the rapid increase in the application of biochars as amendments, studies are needed to clarify the possible environmental risks derived from biochars to use safely the biomass resources. This work reported selected dark sides of maize straw-and swine manurederived biochars pyrolyzed at 300 and 500°C. During the pyrolysis processes, total heavy metals in the biochars were enriched greatly accompanying with considerable emission of the heavy metals into atmosphere and the trends became increasingly obvious with pyrolysis temperature. Meanwhile, the biochars showed distinctly decreased available heavy metals compared with raw feedstocks, which could be mainly attributed to the sorption by the inorganics in the biochars. The water-and acid-washing treatments significantly increased the releasing risks of heavy metals from biochars into the environments. Electron paramagnetic resonance analysis indicated that persistent free radicals, emerged strongly in the biochars as a function of the aromatization of biomass feedstocks, were free from the influence of water-, acid-, or organic-washing of the biochars and could remain stable even after aged in soils for 30 days. Dissolved biochars, highly produced during pyrolysis processes, showed distinct properties including lower molecular weight distribution while higher aromaticity compared with soil dissolved organic carbon.The results of this study provide important perspectives on the safe usage of biochars as agricultural/environmental amendments.