Continuous nitrogen fertilization retards the vertical migration of Fukushima nuclear accident-derived cesium-137 in apple orchard soil.

We monitored the levels of cesium-137 (137Cs) in the soils of five orchards for six years following the Fukushima Daiichi Nuclear Power Plant accident on 11 March 2011 and found that the vertical distribution of accident-derived 137Cs varied significantly among the orchards with varying land-use and fertilizer management. Based on these results, this study evaluated how nitrogen (N) fertilizer management may have affected the vertical migration of 137Cs in the orchard soils. We selected an experimental orchard producing 'Jonathan' apples, where a long-term N-fertilizer trial has continued since 1973, with an N-fertilized plot (N plot; N added at 20 g m-2 y-1) and a non-fertilized plot (0 N plot). Five years after the accident, the vertical migration of accident-derived 137Cs was significantly lower in the N plot (2.3 cm) than in the 0 N plot (4.3 cm), suggesting greater 137Cs retention in the surface of the N plot. Application of a cesium bromide (133CsBr) tracer suggested that the retarded vertical migration of 137Cs in the N plot may be related to significantly lower amounts of exchangeable 133Cs and significantly higher proportions of non-exchangeable 133Cs in the upper 2 cm. We did not find any evidence of the aboveground plants contributing to more 133Cs retention in the N plot. However, greater 137Cs retention in the surface (0-2 cm) of the N plot may be due to more dissolved organic carbon (DOC), and high DOC may have contributed to deeper 137Cs migration in both the plots. Our results suggest that continuous N fertilizer application significantly retarded the migration of 137Cs by approximately one-half and resulted in less 137Cs reaching the mobile exchangeable form in the deeper root-zone layers.

Visceral fat accumulation in Japanese high school students and related atherosclerotic risk factors.

AIM: To investigate the factors that influence visceral fat accumulation in adolescence, we performed a medical examination of high school students and assessed abdominal fat thickness and fatty change of the liver. METHODS: A cohort of 374 Japanese high school students aged 15-16 years (193 boys and 181 girls) in public high schools in Chiba prefecture were enrolled. Anthropometric parameters, blood cell count, blood chemistry and adipocytokine levels were measured. Preperitoneal fat thickness (PFT) and echoic contrast of the liver were measured by ultrasonography. RESULTS: Anthropometric parameters, systolic blood pressure, blood cell count, ALT, AST, FBS, gamma-GTP, HDL-C, LpL, UA, adiponectin, resistin and leptin levels differed between sexes. Multivariate regression analysis revealed that leptin was the most appropriate marker for PFT in both sexes (p<0.0001). Visceral obesity, categorized as PFT exceeding 8 mm, was observed in 9.6% of all students. Boys with visceral obesity showed apparent liver dysfunction, hyperlipidemia, hyperinsulinemia, and high leptin and low adiponectin levels. Overall, 16.6% of boys and 30.4% of girls showed hepatorenal echo contrast positivity. Boys with visceral obesity and fatty liver had more risk factors for atherosclerosis. CONCLUSIONS: Physical examination of high school students is important for early detection of atherosclerosis.