Sources, distribution, behavior, and detection techniques of microplastics in soil: A review

In recent years, the problem of environmental pollution caused by microplastics has attracted widespread attention. This paper reviews the latest research progress in terms of the source, content and distribution characteristics, harm, and detection technology of soil microplastics by referring to the relevant literature on soil microplastics worldwide. It concludes that:(1) Existing studies worldwide have detected the presence of microplastics in soil, water, and atmosphere, and the use of agricultural films, sewage sludge,and other man-made activities are the main sources of microplastics in soil;(2) microplastics can adsorb heavy metals, persistent organic pollutants and antibiotics in soil, change the physical and chemical properties of soil. This will result in composite pollution and harm to the ecosystem;(3) microplastics in soil not only can destroy the activity of key soil microorganisms, but also enter the body of crops and soil animals, affecting normal growth of crops and soil animals, and further threaten human health;(4) at present, there is no unified operating standard for the sampling, processing, and detection process of microplastics. Analysis methods such as visual inspection, spectroscopy, and thermal analysis have both advantages and disadvantages, and emerging detection technologies require urgent development.Microplastics have become a new pollutant in soil and their distribution characteristics are closely related to human activities. They pollute the environment and threaten human health through the food chain.Although related research on soil microplastics has just begun, it will become the focus of research in the future.

Study on the Urbanization Process of Kunming City and Its Impact on the Water Environment of Dianchi Lake

[ Objective] We aimed to analyze the urbanization process of Kunming City and its impact on the water environment of Dianchi Lake. [ Method ] Using the Analytic Hierarchy Process （AHP）, we assessed the urbanization leve of Kunming in 1998 -2008 based on composite indicator evaluation system. Afterwards, we calculated water pollution composite index of Dianchi Lake and introduced the EKC to set up a coupling relation- ship model between the urbanization level and water environment quality. [ Result] During 1998 -2008, the urbanization level of Kunming increased gradually, that is, it was lower than 30.0% before 2002, with slow growth; at the later stage, it grew fast, and reached 75.0% in 2008. Water pol- lution composite index of Dianchi Lake showed that Dianchi Lake was polluted seriously, especially Caohai. From the EKC, we can see that the re- lationship curves between the urbanization level of Kunming and water pollution composite index of Dianchi Lake were akin to inversed U shapes and still at an antagonistic stage at present. [ Condusion] The research could provide scientific references for discussing the relationship between urban- ization process and water environment.

Fabrication of Bi_2O_3/TiO_2nanocomposites and their applications to the degradation of pollutants in air and water under visible-light

A nanoheterojunction composite photocatalyst Bi2O3/TiO2 working under visible-light （λ≥ 420 nm） was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2 molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2 nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3.

Health Risk Assessment of Groundwater Pollution—A Case Study of Typical City in North China Plain

This article presents an application of assessing human health risk in typical city of North China plain.Combined with water quality and multi-element analysis,Pb,Cd,Cr^6＋,Mn,NO3^-,F^-,and As in groundwater samples were chosen to be used for human health risk assessment of drinking water pathway and dermal contact pathway,and results show a good effect.Results indicate that（1） poor water quality is caused by salinity and hardness overstandard;（2） in noncarcinogenic risk,samples that do not pose noncarcinogenic risk only account for 28.46%;in carcinogenic risk,samples that do not pose carcinogenic risk account for 73.08%;（3） the noncarcinogenic risk in the study area decreased in the following order：NO3^-〉Mn〉As〉F-〉Cr^6＋〉Cd〉Pb and the carcinogenic risk of the study area de-creased in the following order：As〉Cd=NO3^-=Mn=F-=Cr^6＋=Cd=Pb=0,because the slop factors were not available for the other pollutants,except for As;and（4） in terms of whole study area,the main contrib-ute order of drinking water pathway and dermal contact pathway in human body is drinking water pathway〉dermal contact pathway.

A vehicle-mounted dual-smog chamber:Characterization and its preliminary application to evolutionary simulation of photochemical processes in a quasi-realistic atmosphere

Smog chambers are the effective tools for studying formation mechanisms of air pollution.Simulations by traditional smog chambers differ to a large extent from real atmospheric conditions,including light,temperature and atmospheric composition.However,the existing parameters for mechanism interpretation are derived from the traditional smog chambers.To address the gap between the traditional laboratory simulations and the photochemistry in the real atmosphere,a vehicle-mounted indoor-outdoor dual-smog chamber(JNUVMDSC)was developed,which can be quickly transferred to the desired sites to simulate quasi-realistic atmosphere simultaneously in both chambers using“local air”.Multiple key parameters of the smog chamber were characterized in the study,demonstrating that JNUVMDSC meets the requirements of general atmospheric chemistry simulation studies.Additionally,the preliminary results for the photochemical simulations of quasi-realistic atmospheres in Pearl River Delta region and Nanling Mountains are consistent with literature reports on the photochemistry in this region.JNU-VMDSC provides a convenient and reliable experimental device and means to study the mechanism of atmospheric photochemical reactions to obtain near-real results,and will make a great contribution to the control of composite air pollution.