No abstract

Research on the occurrence of perfluorochemicals (PFCs) such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in the agricultural environment is lacking, in spite of their potential risk via food chain transfer from aquatic and soil-plant systems to animals and/or humans. In the present study, for the first time, soil and water samples collected from 243 different agricultural sites adjacent to waste water treatment plants (WWTPs) belonging to 81 cities and 5 provinces with different levels of industrialization in South Korea were monitored for concentrations of PFOS and PFOA by use of solid phase extraction and liquid chromatography-tandem mass spectroscopy (LC-MS/MS). Significant mean concentrations of PFOA (0.001-0.007 µg L-1 water and <0.05-1.573 µg kg-1 soil) and PFOS (0.001-0.22 µg L-1 water and <0.05-0.741 µg kg-1 soil) were found in all samples. Concentrations of PFCs in soils were high, highlighting that soil is an important sink for PFCs in the agricultural environment. Samples from near WWTPs in Gyeongsang Province contained the highest concentrations of PFOS and PFOA, reflecting the concentration of heavy industry in the province. The concentrations of PFCs in agricultural water (most samples <0.05 µg L-1) and soils (most samples <1 µg kg-1) from South Korea were less than acceptable guideline values, indicating that South Korea is not a hotspot of PFOS and PFOA contamination and that there is negligible risk to human and ecological health from these chemicals. However, further studies investigating the seasonal variation in PFOA, PFOS and other perfluorochemical concentrations in the agricultural environment are needed.

Poly(lactic acid) (PLA) and poly[(butylene adipate)-co-terephthalate] (PBAT) are both commonly used biodegradable polymers. In this study, co-extrusion of PLA and PBAT was used to create alternately multilayered films in order to obtain high-flexibility PLA film. The incorporation of PBAT provides enhanced flexibility to PLA and the effect is more distinct in the PLA/PBAT multilayer film as the number of layers increases. Through differential scanning calorimetric and wide-angle X-ray scattering analyses, the crystallinity of PLA is shown to decrease more in the multilayer film than in the blended film. Transparency is also enhanced in the multilayer film. The fabrication of alternate multilayered film by co-extrusion of PLA and PBAT shows a new method of preparing a flexible, transparent and fully biodegradable film, which is impossible through a blending process.