Soil organic carbon (SOC) represents the most dynamic component of the soil carbon pool and is pivotal in the global carbon cycle. Global temperature rise and increasing drought severity are now indisputable realities, making soil organic carbon cycling under climate warming a critical research priority. This review elucidates the mechanism of the SOC response to temperature increase in terms of both extrinsic and intrinsic factors. The extrinsic factors are temperature elevation methods, rainfall, and land use. Different methods of temperature increase have their own unique advantages and disadvantages. Indoor warming methods exclude other factors, making temperature the only variable, but tend to ignore carbon inputs. In situ field warming and soil displacement methods help researchers explore the response of the complete ecosystem carbon cycle to temperature increase but cannot exclude the interference of factors such as rainfall. Elevated rainfall mitigates the adverse effects of elevated temperatures on organic carbon sequestration. In addition, the response of SOC to temperature elevations vary among different land use types. The temperature sensitivity of SOC is higher in peatland (high organic matter) alpine meadows (colder regions). The intrinsic factors that affect the response of SOC to elevated temperatures are SOC components, microorganisms, SOC temperature sensitivity, and SOC stability. The SOC decomposition rate is influenced by variations in the ratios of decomposable (easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC)) and stabilizing (inert organic carbon (IOC), alkyl carbon, and aromatic carbon) SOC to total organic carbon (TOC). Furthermore, temperature elevations also affect the soil microenvironment, resulting in microbial community reorganization such as changes in bacterial and fungal ratios and abundance. At the same time, soil aggregates, clay minerals, and iron and aluminum oxides protect the SOC, making it difficult to be utilized by microbial decomposition. The systematic clarification of the mechanism behind the SOC response to higher temperatures is crucial for accurately predicting and modeling global carbon cycles and effectively responding to the loss of SOC pools due to global temperature elevations.

Soil organic carbon (SOC) is an important part of the global C pool and is sensitive to climate change. The SOC content and fractions of rice paddies along four elevations (250, 1150, 1600 and 1800 m) on the same slope in four seasons (spring, summer, autumn and winter) at Yuanyang Terrace in southwest China were investigated, and their relationship with environmental factors was analyzed. The contents of SOC, unprotected SOC (uPOM), physically protected SOC (pPOM) and biochemically protected SOC (bcPOM) in rice paddies at a low elevation (250 m), were significantly lower by 49–51% than those at relatively high elevations (1600 m and 1800 m). Among the SOC fractions, the highest proportion (33–50%) was uPOM, followed by pPOM and bcPOM (accounting for 17–40%), and the lowest proportion was chemically protected SOC (cPOM). In addition, there were interseasonal differences among the contents of SOC fractions, with a significantly higher content of SOC, uPOM and pPOM at an elevation of 1600 m in summer than in the other three seasons, whereas the cPOM content at an elevation of 250 m in spring was significantly higher than in the other three higher elevations. According to the redundancy analysis (RDA), total nitrogen was the key environmental factor, with an explanatory degree of 56% affecting the contents of SOC and its fractions. Thus, the SOC content increased with increasing elevation, and physical and biochemical protection were potential stabilization mechanisms responsible for their stability in the rice paddy of Yuanyang Terrace. These results provides empirical evidence for the elevational distribution patterns and seasonal dynamics of SOC fractions in rice paddies across Yuanyang Terrace. These findings highlight the importance of physical and biochemical protection mechanisms in stabilizing SOC in rice paddies, which could enhance long-term C sequestration and contribute to climate change mitigation in terraced agroecosystems.

When preparing lightweight ceramsite using carbide slag, trace amounts of toxic elements are released into the atmosphere due to high-temperature calcination, posing a significant risk to the environment. The real-time monitoring of the released gases is challenging under laboratory conditions while preparing large quantities of ceramsite. Therefore, heating was simulated using experimental data and the FactSage 7.0 thermochemical database to study the release of harmful Al-, C-, H-, S-, and F-containing elements when using carbide slag to prepare lightweight ceramsite. The results indicated that no Al, C, H, S, or F elements were evident in the high-temperature liquid products obtained in a 50 °C to 1150 °C calcination temperature range. Al was present in a solid state with no gaseous products. When the temperature reached 450 °C, CO gas was released and its level increased as the temperature rose. H and S mainly combined into H₂S gas, starting at 250 °C and reaching a peak at 1050 °C. H and F primarily combined into HF, starting at 400 °C. Other F-containing gases mainly included SiF₄ and TiF₃, which began to release at 800 °C and 900 °C, respectively. The release trends of HF, SiF₄, and TiF₃ were consistent with those of CO. This study aimed to conduct an environmental impact and management assessment for the preparation of lightweight ceramsite using carbide slag. The use of raw material carbide slag for the low-cost treatment of tail gas was proposed, which provides theoretical and up-to-date support for greening the application of the process.

To address the contradiction between the widespread prevalence of selenium deficiency and the growing demand for selenium-enriched fruits, this study utilized phosphate tailings (industrial solid waste), wood vinegar (a by-product of forestry processing), biochemical fulvic acid, and alginic acid (renewable biomass resources) to construct an organic–inorganic composite soil selenium activator. This formulation enhances the mobilization of inherent selenium in the soil without relying on exogenous selenium supplementation, thereby improving selenium bioavailability while mitigating the environmental pollution and resource depletion associated with external selenium inputs. Through field experiments, we systematically evaluated the influence of varying activator dosages on soil physicochemical properties, available selenium content, selenium distribution in different citrus organs, and fruit quality. The results demonstrated that the application of the compound activator at 600 g/plant significantly increased (p < 0.05) soil available selenium and fruit selenium content by 21.26% and 21.06%, respectively. During the fruit expansion stage of Sugar Orange, soil available selenium was elevated by 21.8%, which corresponded to a 21.09% increase in fruit selenium content. Regarding fruit quality parameters, Sugar Orange exhibited increases in soluble solids (35.8%), citric acid (20.3%), solid-to-acid ratio (77.8%), and selenium content (223.3%). In Rock Sugar Orange, significant enhancements were observed in soluble solids (46.1%), vitamin C (45.3%), total soluble sugars (73.4%), solid-to-acid ratio (156.6%), and selenium content (69.7%). Structural equation modeling revealed that soil available selenium, soil properties, and selenium content in citrus organs collectively exerted positive regulatory effects on fruit quality. Specifically, juice selenium content showed significant positive correlations with fruit shape index, individual fruit weight, soluble solids content, and solid-to-acid ratio. This strategy achieves the synergistic reuse of industrial solid waste and agricultural biomass resources, offering a green and sustainable pathway to enhance selenium content and quality in citrus fruits.