[Analysis and Simulation of the Spatiotemporal Evolution of Habitat Quality and Carbon Storage in the Weibei Dry Plateau Region of Shaanxi].

Exploring the spatial and temporal pattern evolution of habitat quality and carbon storage has a positive feedback effect on establishing an ecological security barrier and optimizing the spatial pattern of national land in the WeiBei Arid Plateau Region of Shaanxi. This study took the Weibei Plateau Region as a case study, simulated the spatial pattern of land use for different development scenarios of 2035 based on the PLUS model, and used the InVEST model to analyze the characteristics of habitat quality and carbon storage distribution in the study area from 1980 to 2020 and under multi-scenarios in the future. The results showed that:①the area of the low-grade habitat quality area in the study area expanded by 462.55 km2, and the carbon stock decreased by 7.85×106 t over the past 40 years, both of which showed an overall decreasing trend yearly. ②During the study period, the degraded habitat quality areas were concentrated in the northeastern part of the study area within Yan'an City, and the upgraded areas were distributed in strips near water sources or at higher elevations. The high carbon stock areas were concentrated in the complex terrain and sparsely populated areas in the study area, and the decreasing carbon stocked areas were scattered throughout the study area in a dotted pattern without obvious aggregation. ③In 2035, carbon stock decreased to different degrees in all states except for the natural development scenario. In the economic priority development scenario, the habitat quality low grade area covered 20787.41 km2, which was the simulated scenario of the fastest growth rate of low-grade area and the largest reduction of high-grade area compared with the early stage of the simulation. The results of this study can provide decision references and data support for low carbon green development and ecological restoration in the study area.

Voltammetric and spectral characterization of two flavonols for assay-dependent antioxidant capacity.

Polyphenolic compounds usually showed different antioxidant capacities depending on the assay methods used. To determine the possible chemical cause for this assay-dependence, two flavonols, kaempferol and morin, were selected as the model molecules for the comparative investigation between electrochemical and chemical oxidations. The electro-oxidation of the flavonols was studied using cyclic voltammetry and in situ UV-Vis spectroelectrochemical technique with a long-optical-path thin-layer electrolytic cell. The spectral changes recorded in different potentials were compared with those in the chemical oxidation by H(2)O(2) or ABTS(*+) radical in the same thin-layer cell. The 4'-OH group of either sample was first oxidized at lower potentials or induced by H(2)O(2), and in this case kaempferol was somewhat more active than morin. With an additional 2'-OH group, morin underwent the secondary oxidation in moderately higher potentials or by ABTS(*+), showing antioxidant capacity about twice of that of kaempferol. This study clarified that the chemical oxidation of a polyphenolic compound by the oxidants with different reactivities, which corresponded to its electro-oxidation in different anodic peaks, had a difference in number of oxidizable OH-groups, leading to the difference in antioxidant capacity.