Liquid phase transformation mechanism of ß-caryophyllonic acid initiated by hydroxyl radicals and ozone in atmosphere.

ß-caryophyllonic acid (BCA), as an important precursor of aqueous secondary organic aerosols (aqSOA), has adverse effects on the atmospheric environment and human health. However, the key atmospheric chemical reaction process in which BCA participates in the formation of aqueous secondary organic aerosols is still unclear. In this study, the reaction mechanism and kinetics of BCA with ·OH and O3 were investigated by quantum chemical calculations. The initiation reactions between BCA and ·OH include addition and H-abstraction reaction pathways, subsequent intermediates will also react with O2, ultimately undergo a cracking reaction to generate small molecular substances. The reaction of BCA with O3 can generate primary ozone oxides and the Criegee Intermediates oIM3, subsequent main reaction products include keto-BCA, as well as other small molecule aqSOA precursors. The entire reaction process increases the O/C ratio of aqSOA in the aqueous phase and generates products of small molecules such as 4-formylpropionic acid, which plays an important role in the formation of aqSOA. At 298K, the transformation rate constants of BCA initiated by ·OH and O3 are 1.47 × 1010 M-1 s-1 and 3.16 × 105 M-1 s-1, respectively, the atmospheric lifetimes of BCA reacting with ·OH range from 0.86 h-5.40 h, while the lifetimes of BCA reacting with O3 range from 0.44 h-10.04 years. This suggests that BCA primarily reacts with ·OH. However, under higher O3 concentrations, its ozonolysis becomes significant, promoting the formation of aqSOA. According to the risk assessment, the toxicity of most transformation products (TPs) gradually decreased, but the residual developmental toxicity could not be ignored. In this paper, the atmospheric liquid phase oxidation mechanisms of sesquiterpene unsaturated derived acid were studied from the microscopic level, which has guiding significance for the formation and transformation of aqSOA in atmosphere.

Coupling coordination of new urbanization in Chinese urban agglomeration-characteristics and driving factors.

The coordinated development of new urbanization (NU) in urban agglomerations (UAs) is key for promoting sustainable urban development and the way to achieve Chinese-style modernization. Based on the mechanisms of coupling and coordination of NU, the internal subsystem coupling coordination of NU was deconstructed into five dimensions-economic, population, land, social, and ecological. Using 200 cities in 19 Chinese UAs areas, the spatio-temporal evolution characteristics of the coupling coordination degree of NU (CCDNU) were analyzed, and the driving factors were analyzed from both spatial spillover effect and stratification heterogeneity. The results are as follows: (1) CCDNU has increased from moderate disorder to barely coordinated, exhibiting a spatial distribution of a higher CCDNU in the east and lower CCDNU in the west with a positive global spatial autocorrelation feature; (2) economic drive, population concentration, spatial carrying capacity, and environmental quality play facilitating roles in the CCDNU of the study region, while the spatial carrying capacity, quality of life, and environmental quality inhibit the CCDNU of neighboring regions. From the decomposition of long- and short-term effects, both direct and indirect effects of driving factors were found to accumulate significantly over time. In addition, the model results were robust after replacing the geographic distance weight matrix and excluding the extreme values; (3) the spatial carrying capacity, population concentration, and economic drive are the dominant factors affecting the CCDNU in China. The dominant driving factors of are different in different regions. Meanwhile, the interaction detection shows that the interaction of each driver exhibits a two-factor enhancement or non-linear enhancement. Based on these results, corresponding policies are recommended.

Different bacterial and fungal community patterns in restored habitats in coal-mining subsidence areas.

Soil microbiota, which plays a fundamental role in ecosystem functioning, is sensitive to environmental changes. Studying soil microbial ecological patterns can help to understand the consequences of environmental disturbances on soil microbiota and hence ecosystem services. The different habitats with critical environmental gradients generated through the restoration of coal-mining subsidence areas provide an ideal area to explore the response of soil microbiota to environmental changes. Here, based on high-throughput sequencing, we revealed the patterns of soil bacterial and fungal communities in habitats with different land-use types (wetland, farmland, and grassland) and with different restored times which were generated during the ecological restoration of a typical coal-mining subsidence area in Jining City, China. The α-diversity of bacterial was higher in wetland than in farmland and grassland, while that of fungi had no discrepancy among the three habitats. The ß-diversity of bacterial community in the grassland was lower than in the farmland, and fungal community was significant different in all three habitats, showing wetland, grassland, and farmland from high to low. The ß-diversity of the bacterial community decreased with restoration time while that of the fungal community had no significant change in the longer-restoration-time area. Furthermore, soil electrical conductivity was the most important driver for both bacterial and fungal communities. Based on the taxonomic difference among different habitats, we identified a group of biomarkers for each habitat. The study contributes to understand the microbial patterns during the ecological restoration of coal-mining subsidence areas, which has implications for the efficient ecological restoration of subsidence areas.

Habitats generated by the restoration of coal mining subsidence land differentially alter the content and composition of soil organic carbon.

The content and composition of soil organic carbon (SOC) can characterize soil carbon storage capacity, which varies significantly between habitats. Ecological restoration in coal mining subsidence land forms a variety of habitats, which are ideal to study the effects of habitats on SOC storage capacity. Based on the analysis of the content and composition of SOC in three habitats (farmland, wetland and lakeside grassland) generated by different restoration time of the farmland which was destroyed by coal mining subsidence, we found that farmland had the highest SOC storage capacity among the three habitats. Both dissolved organic carbon (DOC) and heavy fraction organic carbon (HFOC) exhibited higher concentrations in the farmland (20.29 mg/kg, 6.96 mg/g) than in the wetland (19.62 mg/kg, 2.47 mg/g) or lakeside grassland (5.68 mg/kg, 2.31 mg/g), and the concentrations increased significantly over time, owing to the higher content of nitrogen in the farmland. The wetland and lakeside grassland needed more time than the farmland to recover the SOC storage capacity. The findings illustrate that the SOC storage capacity of farmland destroyed by coal mining subsidence could be restored through ecological restoration and indicate that the recovery rate depends on the reconstructed habitat types, among which farmland shows great advantages mainly due to the nitrogen addition.