ABSTRACT
The role of mangroves in carbon sequestration is critical in mitigating climate change. For better identifying the carbon conservation hotspots of mangroves influenced by environmental factors, the spatial distribution and driving mechanisms of mangrove vegetation and soil carbon sequestration, as well as the future carbon dynamics of mangroves, required clarification. Firstly, we assessed the spatial pattern of vegetation biomass and soil depth-varied soil total organic carbon (TOC) in Xiaoguansha, Guangxi Province of China, and its relationships with duration of inundation (DTI) were explored. Additionally, the carbon storage capacity of adjacent mangrove tidal flats as potential carbon reservoirs was quantified. Thirdly, freshwater, and nutrient inputs, biotic factors of mangrove, and soil composition were selected as impact factors, and their mechanisms in carbon sequestration were elucidated by using Partial least squares path modeling (PLS-PM). Finally, medium values of environmental factors on mangrove carbon sequestration were revealed, based on which future loss and gain patterns of carbon sequestration under the combined effects were fully discussed. The results showed that: (1) The Above-ground biomass (AGB) and TOC densities were 32.89 Mg C/ha and 185.10 Mg C/ha in the study area, and both were enriched in the Interior areas. The carbon sequestration in the tidal flats was equivalented to >1/5 of total carbon sequestration of mangroves. (2) DTI was the most critical factor affecting the carbon sequestration pattern and was found to be positive correlated with AGB and TOC via changing soil contents (SC), whereas it exhibits a negative correlation with AGB and TOC through influencing canopy density (CD). CD and TP were identified as significant predictors. (3) Median analysis indicated that future carbon 'gain' area will move nearshore, whereas the carbon-rich intertidal area may undergo carbon loss. This study provided new insights and scientific understanding for management of mangrove blue carbon function.
ABSTRACT
Step-scheme (S-scheme) photocatalysts have been proposed for highly efficient charge separation and strong redox activity in the photocatalysis field. Here, we reported a facile strategy to obtain the S-scheme heterojunction composite TiO2/chlorophyll (Chl). The S-scheme heterojunction enables the significant improvement of electron transfer efficiency at the interfacial heterojunction of TiO2/Chl. Also, the lifted conduction band and valence band of TiO2/Chl resulted in more than 1.61 times generation of reactive oxidizing species, compared to that of bare TiO2. In addition, TiO2/Chl was applied as a photocatalytic bactericidal material to fabricate commercial masks for prolonged life span of the mask. The TiO2/Chl-coated mask filter exhibited excellent bactericidal effect on Escherichia coli under light illumination (2.94 × 107 cfu E. coli were killed by 1 cm-2 coated mask filters within illumination of 3 h), while commercial mask filters showed no bactericidal effect. After three circulation-sterilization tests, the TiO2/Chl-made mask filter maintained the initial bactericidal effect, which greatly extended the life span of the mask that presents a promising strategy to alleviate the supply stress of masks.