Stress response to nanoplastics with different charges in Brassica napus L.during seed germination and seedling growth stages

Nanoplastic pollution has become a significant problem in farmland systems worldwide.However,research on the effects of nanoplastics(NPs)with different charges on field crops is still limited.In our study,NPs with different charges,including unmodified polystyrene nanoplastics(PS),positively charged polystyrene nanoplastics(PS-NH_(2)),and negatively charged polystyrene nanoplastics(PSSO3H),were investigated for their impacts on seed germination and seedling growth of rape.The results showed that seed water uptake(after 12 h),seed germination,seed vigour,and relative root elongation were all significantly reduced under exposure to NPs(200 mg/L).Similarly,remarkable decreases in plant biomass(root weight,shoot weight),growth(root length,plant height),photosynthesis ability(chlorophyll a,chlorophyll b,carotenoids),essential nutrient uptake(Fe,Mn,Zn,Cu),and plant quality(soluble protein,soluble sugar,crude fibre content)of rape seedlings were also observed after exposure to NPs.Among the three kinds of NPs,PS-NH_(2)showed stronger effects.Moreover,superoxide dismutase,peroxidase,and catalase activities of rape seedlings were changed,and the content of malondialdehyde was significantly increased under exposure to NPs.Furthermore,positively charged PS-NH_(2)showed stronger effects on the phenotype,physiology,biochemistry,nutrient uptake,and plant quality of rape.Notably,a comprehensive toxicity evaluation revealed that PS-NH_(2)had the strongest toxicity to rape.The present study provides important implications for the interaction and risk assessment of NPs and crops in soil-plant systems.

Temporal–spatial distribution and diastereoisomer pattern of hexabromocyclododecane in the vicinity of a chemical plant

Hexabromocyclododecane(HBCD) is an effective brominated flame-retardant additive, which is mainly produced in the coastal area of China. This study collected soil samples from a HBCD production plant and its surrounding area in Weifang, Shandong Province, China, and analyzed the temporal–spatial distribution of HBCD and its diastereoisomers in soil. The analysis results showed that the concentration of HBCD in soil near the plant was much higher than normal values, with an annual average concentration reaching 5405 ng/g. Soils 1,2 and 4 km away from the plant were also analyzed, showing that the concentration of HBCD in soil decreased accordingly with the distance from the pollution sources. In order to investigate the effect of the season on HBCD content, the soil samples were collected in all four seasons of the year 2017–2018. According to variations in the wind direction, the concentration of HBCD in soil was also changed. The distribution trend showed that the concentration of HBCD in soil in the downwind direction of the prevailing wind was higher than that in the upwind direction. In addition, this work analyzed the distribution of HBCD in vertical soil sections. It was found that the concentration of HBCD decreased with depth in the soil vertical profile. Finally, the various diastereoisomer patterns in the soil compartments were examined, finding that α-HBCD and γ-HBCD were the predominant diastereoisomers in the soil of the study area.

An extraction-assay system： Evaluation on flavonols in plant resistance to Pb and Cd by supercritical extraction-gas chromatography

In this research, supercritical carbon dioxide extraction （SFE） showed better extraction etlect when compared with Solid- liquid extraction （SLE）, Soxhlet extraction （SEt and Ultrasonic extraction （UE）, not only in the rate but also the time. The comparison among these three extraction modifiers, including acetone, ethanol and methanol demonstrated that ethanol was preferred to SFE due to its high extraction effect and low toxicology. In addition, parameter of SFE, influence of temperature and pressure were investigated, and the best extraction effect was achieved at the optima conditions, temperature of 40℃ and the pressure of 35 MPa. Thus, SFE is a highly effective method for flavonols extraction, requiring minimum energy and producing non-toxic byproduct. SFE-GC system is applied for the evaluation on flavonols that plays a key role in plant resistance to heavy metal, with its content and synthetase gene expression significantly increasing in plant when threatened by heavy metal. Besides, results indicated that flavonols can improve plant resistance to oxidative stress by quenching the redundant ROS in matrix.