Search

In forests, microbial populations in the soil can directly influence the decomposition of carbon from surface plants, promoting carbon storage and stability. However, in sustainable forest management, it is still unclear how soil microorganisms under different plantation types affect organic carbon sequestration and whether the mechanisms of influence are the same. In this research, we focused on four mixed forests and pure Pinus massoniana-planted forest in the state-owned forest farm of Dushan County. Three replicated plots were set up for each model, and soil samples were collected from different layers (0–20 cm, 20–40 cm, and 40–60 cm), totaling 45 samples. We elucidated the effects of soil microorganisms on carbon sequestration under five mixed modification models of P. massoniana and further explored the mechanisms by which microbial functional communities regulate soil carbon sequestration under different mixed models through molecular sequencing and collinear network analysis. Variance analysis indicated that the soil organic carbon (SOC) of the same soil layer varied significantly, and there were also significant differences in the composition of soil bacterial and fungal microbial communities. Moreover, the bacterial community was more sensitive to changes in the vegetation environment, while the fungal community structure was more resistant to changes in the soil environment. Correlation analysis indicated that the diversity and composition of the bacterial community had more positive effects on soil organic carbon than those of the fungal community. Linear fitting and redundancy analysis (RDA) showed that particulate organic carbon (POC) in soil had the strongest correlation with SOC content. Soil microorganisms affected the storage and stability of soil carbon mainly by regulating the conversion of litter (carbon sources) into POC. The soil environment of different mixed models had different effects on soil carbon accumulation. Both correlation and collinearity network analyses indicated that soil microbial functional groups could enhance carbon storage by regulating readily oxidizable carbon (EOC) and POC content in mixed forest plantations. The results of our study provide a sound basis for replanting a reasonable forest model structure to improve forest carbon storage. [ABSTRACT FROM AUTHOR]

Sulfate radical-based advanced oxidation technologies (SR-AOTs) are very effective solutions to remove organic pollutants from wastewater. Nevertheless, difficulties remain in finding an efficient and environmentally friendly catalytic system to activate peroxymonosulfate (PMS) for the oxidation process. In this work, a simple impregnation method for synthesizing layered Co(OH)2 deposited g-C3N4 (Co(OH)2/g-C3N4) was developed. The as-obtained Co(OH)2/g-C3N4 showed excellent performance in the destruction of various organic pollutants through PMS activation. The structure, morphology and composition of Co(OH)2/g-C3N4 were analyzed using diverse characterization methods. Various experimental parameters such as catalyst loading, initial PMS concentration, pH, reaction temperature and initial organic pollutant concentration were studied in detail. The obtained Co(OH)2/g-C3N4 composite can completely degrade Rhodamine B (RhB) with a high reaction rate constant of 0.460 min−1 under the optimal conditions, which was much higher than those of Co(OH)2, g-C3N4 and many other metal catalysts. This was because the synergistic effect between the layered Co(OH)2 with sufficient active sites and electron-rich g-C3N4 with good electron transfer ability can accelerate the activation of PMS. Besides, radical quenching experiments indicated that sulfate radicals (SO4˙−) were the major active radicals in the PMS activation process. Finally, the degradation pathways and a reasonable reaction mechanism of the Co(OH)2/g-C3N4/PMS system for RhB removal were put forward. The study revealed that Co(OH)2/g-C3N4 could provide appropriate strategies for the removal of organic pollutants in aqueous environments. [ABSTRACT FROM AUTHOR]

Because of its unique reductive properties, nanoscale zero-valent iron (NZVI) has been widely used in soil and groundwater remediation. It is crucial to understand the fate of NZVI in soils. In this work, a range of laboratory experiments was conducted to examine the adsorption, transformation, and transport of NZVI. The NZVI particles showed relatively strong sorption onto vertic shajiang-aquic cambosols, typic-hapli-udic argosols and typic ochri-aquic cambosols and isotherms can be well described by the Langmuir model. When cultivated in the soils, the NZVI was oxidized within seven days and the particle size also increased with average size reaching around 100 nm at 28 days. Columns were packed with quartz sand, sandy soil and diatomite as saturated porous media to evaluate the role of soil colloids in affecting the transport of NZVI. The results showed that NZVI transport in the columns was strongly affected by medium types, dispersion agent types, and soil colloids. Comparisons of breakthrough curves of different types of dispersed NZVI and corresponding colloid-NZVI revealed that natural soil colloids facilitated NZVI transport in porous media. Findings from this work can provide useful information to better evaluate the applications and impacts of NZVI as an environmental remediation agent. [ABSTRACT FROM AUTHOR]

In order to reveal the effects of reducing the amount of novel nano-carbon humic acid water-retaining fertilizer (CSF) on soil microbial community structure and citrus groWh. [Method] In this study, conventional fertilization was as the control (KC1) in Wanzhou citrus orchard of Three Gorges Reservoir area. CSF reductions by 0% (KC2), 10% (KC3), 20% (KC4), 30% (KC5) and 40% (KC6) were used to analyze the changes of soil bacterial community structure, citrus yield and quality. [Result] The results showed that the observed species, Shannon index, Chao1 index and PD_whole_tree of KC6 were higher than those of KC1, and were the same as KC2. The abundance of Xanthomonadaceae was the highest in KC5. Compared with KC1, the Xanthomonadaceae in KC3, KC4 and KC6 was significantly decreased, and the levels of Nitrosomonadaceae and Pseudomonasaceae were higher than that of KC1 after the treatment of KC6. Sphingomonas in different reduction treatments was lower than that of KC1, but Burkholderia and Pseudomonas were significantly higher than those of KC1. It was found that the similarity among treatments was small after bacterial community similarity clustering analysis, and citrus yield increased somewhat after CSF fertilization reduction. When CSF fertilization reduced by 30%, citr [ABSTRACT FROM AUTHOR]