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Organic carbon (OC) sequestration through soil aggregation is an important aspect of land use change/conversion (LUCC) influencing the terrestrial ecosystem C cycle, although little is known on the changes in aggregate dynamics and their contributions to OC accumulation after LUCC in regions with serious soil erosion. Therefore, bulk soil samples under four land uses (farmland and three vegetated soils converted from farmland 42 years ago: Robinia pseudoacacia [RP42yr], Caragana korshinskii [CK42yr], and abandoned land [AL42yr]) in the Loess Plateau, China, was collected, separated into seven aggregate size fractions, and examined for OC content. Farmland conversion into AL42yr, CK42yr, and RP42yr increased macroaggregate (>2 mm) and mesoaggregate (2–0.25 mm) proportions, mean weight diameter, and geometric mean diameter but decreased microaggregates (0.25–0.053 mm) amount. Bulk soil and aggregates OC content and stock varied with soil depth and land use types but were usually highest in RP42yr. Mesoaggregates contained higher OC content and stock than other aggregates at 0‐ to 20‐cm depth under all land uses. Increases in the OC stocks of mesoaggregates accounted for 46% and 85% of the increase in bulk soil OC stocks at 0‐ to 20‐ and 20‐ to 40‐cm depth, respectively. Thus, soil OC accumulation after LUCC is mainly due to increased OC stock within mesoaggregates, which is further attributed to increased mesoaggregate proportions. Overall, vegetation restoration promotes the physical protection of OC by increasing soil aggregation, being a management option to enhance the C sequestration potential in ecological fragile regions.

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Understanding tumor metabolism holds the promise of new insights into cancer biology, diagnosis and treatment. To assess human cancer metabolism, here we report a method to collect intra-operative samples of blood from an artery directly upstream and a vein directly downstream of a brain tumor, as well as samples from dorsal pedal veins of the same patients. After performing targeted metabolomic analysis, we characterize the metabolites consumed and produced by gliomas in vivo by comparing the arterial supply and venous drainage. N-acetylornithine, D-glucose, putrescine, and L-acetylcarnitine are consumed in relatively large amounts by gliomas. Conversely, L-glutamine, agmatine, and uridine 5-monophosphate are produced in relatively large amounts by gliomas. Further we verify that D-2-hydroxyglutarate (D-2HG) is high in venous plasma from patients with isocitrate dehydrogenases1 (IDH1) mutations. Through these paired comparisons, we can exclude the interpatient variation that is present in plasma samples usually taken from the cubital vein.