Oligomers from the Synthetic Polymers:Another Potential Iceberg of New Pollutants

Pollution generated by synthetic polymers,particularly plastics,has become a significant global environmental problem.However,when compared to polymer-derived products like microplastics,oligomers have not received the attention they deserve.Oligomers are by-products of polymer production and intermediates of degradation.Despite the industrial advancements leading to an exponential increase in the production of new polymers,a majority of oligomers have remained inadequately researched.While the exposure and toxic effects of polylactic acid oligomers have been documented,the structures and fundamental properties of oligomers derived from most polymers are still poorly understood.This knowledge gap presents challenges in establishing effective analytical methods.Considering the potential of oligomers to act as new pollutants,it is imperative to investigate their environmental behavior,as well as their absorption,distribution,metabolism,excretion,and toxicity(ADMET)properties.This perspective highlights the research gap concerning oligomers.

Emerging Chemicals in China:Historical Development,Current Situation,and Future Outlook

There has been a widespread international consensus to enhance the regulation of emerging chemicals in the 21st century.The substantial implementation work conducted over the past two decades has established a strong foundation for the control of emerging chemicals across the world.Nevertheless,distinct challenges confront countries and regions due to the ever-evolving diverse national conditions.China,as a developing nation and a major consumer of chemicals,is encountering particularly severe hurdles.This Perspective presents an overview encompassing the historical progression,current circumstances,and challenges confronted by China with regard to emerging chemicals.The central goal of these efforts is to prioritize the control of emerging chemicals and actively establish a monitoring mechanism.Additionally,it is necessary to develop a multistakeholder environmental risk prevention and control system.Ultimately,comprehensive efforts to enhance green substitution practices and active engagement of governance initiatives will be required.

Characterization of particle number size distribution and new particle formation in Southern China

Knowledge of particle number size distribution（PND） and new particle formation（NPF）events in Southern China is essential for mitigation strategies related to submicron particles and their effects on regional air quality,haze,and human health.In this study,seven field measurement campaigns were conducted from December 2013 to May 2015 using a scanning mobility particle sizer（SMPS） at four sites in Southern China,including three urban sites and one background site.Particles were measured in the size range of15-515 nm,and the median particle number concentrations（PNCs） were found to vary in the range of 0.3× 10~4-2.2 × 10~4 cn^（-3） at the urban sites and were approximately 0.2 × 10~4 cm^（-3） at the background site.The peak diameters at the different sites varied largely from 22 to 102 nm.The PNCs in the Aitken mode（25-100 nm） at the urban sites were up to 10 times higher than they were at the background site,indicating large primary emissions from traffic at the urban sites.The diurnal variations of PNCs were significantly influenced by both rush hour traffic at the urban sites and NPF events.The frequencies of NPF events at the different sites were0%-30%,with the highest frequency occurring at an urban site during autumn.With higher SO_2 concentrations and higher ambient temperatures being necessary,NPF at the urban site was found to be more influenced by atmospheric oxidizing capability,while NPF at the background site was limited by the condensation sink.This study provides a unique dataset of particle number and size information in various environments in Southern China,which can help understand the sources,formation,and the climate forcing of aerosols in this quickly developing region,as well as help constrain and validate NPF modeling.