Soil organic carbon (SOC) dynamics are regulated by the complex interplay of climatic, edaphic and biotic conditions. However, the interrelation of SOC and these drivers and their potential ...connection networks are rarely assessed quantitatively. Using observations of SOC dynamics with detailed soil properties from 90 field trials at 28 sites under different agroecosystems across the Australian cropping regions, we investigated the direct and indirect effects of climate, soil properties, carbon (C) inputs and soil C pools (a total of 17 variables) on SOC change rate (rC, Mg C ha−1 yr−1). Among these variables, we found that the most influential variables on rC were the average C input amount and annual precipitation, and the total SOC stock at the beginning of the trials. Overall, C inputs (including C input amount and pasture frequency in the crop rotation system) accounted for 27% of the relative influence on rC, followed by climate 25% (including precipitation and temperature), soil C pools 24% (including pool size and composition) and soil properties (such as cation exchange capacity, clay content, bulk density) 24%. Path analysis identified a network of intercorrelations of climate, soil properties, C inputs and soil C pools in determining rC. The direct correlation of rC with climate was significantly weakened if removing the effects of soil properties and C pools, and vice versa. These results reveal the relative importance of climate, soil properties, C inputs and C pools and their complex interconnections in regulating SOC dynamics. Ignorance of the impact of changes in soil properties, C pool composition and C input (quantity and quality) on SOC dynamics is likely one of the main sources of uncertainty in SOC predictions from the process‐based SOC models.
We quantitatively assessed the interconnections of a series of climatic, edaphic and biotic factors in controlling soil organic carbon (SOC) dynamics. We found that, overall, soil properties, soil C pools, climate and C inputs were almost equally important in terms of overall effect on SOC dynamics. However, if the effect of soil was controlled, the effect of climate was significantly weakened, and vice versa, while the effects of carbon input and soil carbon pool composition were significantly strengthened if climate and/or soil were controlled. These results force us to revise SOC predictions based on modelling and empirical approaches mainly considering climatic factors, and provide new insights into mechanistic understanding of SOC dynamics under different soil and climate conditions across ecosystems.
The large volume expansion induced by K+ intercalation is always a big challenge for designing high‐performance electrode materials in potassium‐ion storage system. Based on the idea that large‐sized ...ions should accommodate big “houses,” a facile‐induced growth strategy is proposed to achieve the self‐loading of MoS2 clusters inside a hollow tubular carbon skeleton (HTCS). Meantime, a step‐by‐step intercalation technology is employed to tune the interlayer distance and the layer number of MoS2. Based on the above, the ED‐MoS2@CT hybrids are achieved by self‐loading and anchoring the well‐dispersed ultrathin MoS2 nanosheets on the inner surface of HTCSs. This unique compositing model not only alleviates the mechanical strain efficiently, but also provides spacious “roads” (hollow tubular carbon skeleton) and “houses” (interlayer expanded ultrathin MoS2 sheets) for fast K+ transition and storage. As an anode of potassium‐ion batteries, the resultant ED‐MoS2@CT electrode delivers a high specific capacity of 148.5 mAh g−1 at 2 A g−1 after 10 000 cycles with only 0.002% fading per cycle. The assembled ED‐MoS2@CT//PC potassium‐ion hybrid supercapacitor device shows a high energy density of 148 Wh kg−1 at a power density of 965 W kg−1, which is comparable to that of lithium‐ion hybrid supercapacitors.
The self‐loading of uniform dispersion ultrathin MoS2 nanosheets on the inner surface of a hollow tubular carbon skeleton is achieved via the surface‐induced growth of MoS2 and step‐by‐step intercalation of double organic molecules. The proper structural design renders the as‐obtained ED‐MoS2@CT materials a more comprehensive electrochemical ability in the potassium‐ion energy storage system.
Abstract
Soil is the largest terrestrial reservoir of organic carbon and is central for climate change mitigation and carbon-climate feedbacks. Chemical and physical associations of soil carbon with ...minerals play a critical role in carbon storage, but the amount and global capacity for storage in this form remain unquantified. Here, we produce spatially-resolved global estimates of mineral-associated organic carbon stocks and carbon-storage capacity by analyzing 1144 globally-distributed soil profiles. We show that current stocks total 899 Pg C to a depth of 1 m in non-permafrost mineral soils. Although this constitutes 66% and 70% of soil carbon in surface and deeper layers, respectively, it is only 42% and 21% of the mineralogical capacity. Regions under agricultural management and deeper soil layers show the largest undersaturation of mineral-associated carbon. Critically, the degree of undersaturation indicates sequestration efficiency over years to decades. We show that, across 103 carbon-accrual measurements spanning management interventions globally, soils furthest from their mineralogical capacity are more effective at accruing carbon; sequestration rates average 3-times higher in soils at one tenth of their capacity compared to soils at one half of their capacity. Our findings provide insights into the world’s soils, their capacity to store carbon, and priority regions and actions for soil carbon management.
Unprecedented levels of nitrogen (N) have been deposited in ecosystems over the past century, which is expected to have cascading effects on microbially mediated soil respiration (SR). Extracellular ...enzymes play critical roles on the degradation of soil organic matter, and measurements of their activities are potentially useful indicators of SR. The links between soil extracellular enzymatic activities (EEAs) and SR under N addition, however, have not been established. We therefore conducted a meta‐analysis from 62 publications to synthesize the responses of soil EEAs and SR to elevated N. Nitrogen addition significantly increased glycosidase activity (GA) by 13.0%, α‐1,4‐glucosidase (AG) by 19.6%, β‐1,4‐glucosidase (BG) by 11.1%, β‐1,4‐xylosidase (BX) by 21.9% and β‐D‐cellobiosidase (CBH) by 12.6%. Increases in GA were more evident for long duration, high rate, organic and mixed N addition (combination of organic and inorganic N addition), as well as for studies from farmland. The response ratios (RRs) of GA were positively correlated with the SR‐RRs, even when evaluated individually for AG, BG, BX and CBH. This positive correlation between GA‐RR and SR‐RR was maintained for most types of vegetation and soil as well as for different methods of N addition. Our results provide the first evidence that GA is linked to SR under N addition over a range of ecosystems and highlight the need for further studies on the response of other soil EEAs to various global change factors and their implications for ecosystem functions.
The Millennial model Abramoff, Rose; Xu, Xiaofeng; Hartman, Melannie ...
Biogeochemistry,
01/2018, Letnik:
137, Številka:
1/2
Journal Article
Recenzirano
Odprti dostop
Soil organic carbon (SOC) can be defined by measurable chemical and physical pools, such as mineral-associated carbon, carbon physically entrapped in aggregates, dissolved carbon, and fragments of ...plant detritus. Yet, most soil models use conceptual rather than measurable SOC pools. What would the traditional pool-based soil model look like if it were built today, reflecting the latest understanding of biological, chemical, and physical transformations in soils? We propose a conceptual model—the Millennial model—that defines pools as measurable entities. First, we discuss relevant pool definitions conceptually and in terms of the measurements that can be used to quantify pool size, formation, and destabilization. Then, we develop a numerical model following the Millennial model conceptual framework to evaluate against the Century model, a widely-used standard for estimating SOC stocks across space and through time. The Millennial model predicts qualitatively similar changes in total SOC in response to single factor perturbations when compared to Century, but different responses to multiple factor perturbations. We review important conceptual and behavioral differences between the Millennial and Century modeling approaches, and the field and lab measurements needed to constrain parameter values. We propose the Millennial model as a simple but comprehensive framework to model SOC pools and guide measurements for further model development.
This study employs entitativity theory to explore how acknowledgment letters from various thankers (e.g., a group of beneficiaries, a charity) influence donors’ subsequent donation desires. This ...empirical research consists of three experiments. Study 1 reveals that an acknowledgment letter from a group of beneficiaries elicits more favorable subsequent donation desires than an acknowledgment letter from a charity. To shed light on the psychological mechanism underlying this effect, Study 2 shows that a categorical appellation can enhance the effects of an acknowledgment letter sent by a charity. Study 3 reveals that the influence of the thanker is stronger under no external pressure conditions (than under external pressure). The current study offers insightful suggestions for the management and administration of charities.
Consumers usually endorse tourism products differently when sharing positive electronic word-of-mouth (eWOM). This research examines the relative persuasiveness of two endorsement styles, that is, ...explicit endorsement (e.g., “I recommend it”) and implicit endorsement (e.g., “I love it”). Drawing on the persuasion knowledge model, we propose that explicit endorsements are less persuasive than implicit endorsements because the former trigger stronger persuasion knowledge. We further argue that source trustworthiness mitigates the persuasion effect difference between the two endorsement styles. This article assesses these hypotheses across different sources (anonymous reviewers, friends, influencers), channels (online community, social commerce platform, social networking app), and products (hotels, restaurants) using secondary data analysis and two experiments. Three studies provide support for our hypotheses. By revealing the relationship between endorsement styles and eWOM persuasiveness, this article provides important implications for implementing effective product endorsement.
Designing Pt-based electrocatalysts with high catalytic activity and CO tolerance is challenging but extremely desirable for alkaline hydrogen oxidation reaction. Herein we report the design of a ...series of single-atom lanthanide (La, Ce, Pr, Nd, and Lu)-embedded ultrasmall Pt nanoclusters for efficient alkaline hydrogen electro-oxidation catalysis based on vapor filling and spatially confined reduction/growth of metal species. Mechanism studies reveal that oxophilic single-atom lanthanide species in Pt nanoclusters can serve as the Lewis acid site for selective OH
adsorption and regulate the binding strength of intermediates on Pt sites, which promotes the kinetics of hydrogen oxidation and CO oxidation by accelerating the combination of OH
and *H/*CO in kinetics and thermodynamics, endowing the electrocatalyst with up to 14.3-times higher mass activity than commercial Pt/C and enhanced CO tolerance. This work may shed light on the design of metal nanocluster-based electrocatalysts for energy conversion.
Since the rapid development of network technology, the rise of live-streaming shopping platforms has followed. Some streamers influence consumers' preferences for products through their gender role ...attributes, thus generating great commercial value. Based on attachment theory and using an experimental approach, this study explored the impact of streamers' gender roles (single gender/androgyny) on consumers' preferences through 2 studies. Study 1 shows the androgynous streamer elicits a higher product preference than the single-gender (masculine and feminine) streamer. Study 2 demonstrates the moderating effect of gender stereotypes through 2 experiments to construct clear boundary conditions for the main effect and the results show that regardless of whether the streamer is male or female when individuals have a high gender stereotype, the single-gender streamer leads to a higher product preference than the androgynous streamer. When individuals have a low gender stereotype, the androgynous streamer promotes a higher product preference than the single-gender streamer.
On social media, luxury brand managers often use influencers' bragging language as a marketing tool. As modesty is considered a virtue in the Chinese context, Chinese influencers tend to adopt a ...humblebragging language style. Research has examined the impact of bragging language styles on luxury brands and has found that humblebragging, which appears to be modest, has a negative influence on brand attitudes. From the perspective of social comparison theory, we proposed a dual mediation model of malicious envy and trustworthiness to reveal the internal mechanisms and moderating factors of the negative effects of humblebragging. The results of three experiments indicated that compared with straightforward bragging, humblebragging was more likely to elicit malicious envy and lower levels of trust in an influencer, resulting in negative attitudes toward the luxury brand endorsed. Moreover, this negative effect was stronger when the influencer lacked expertise or had high similarity with consumers. Our findings enrich the antecedents of social media influencer marketing and provide managers with implications for maximizing the effectiveness of influencer marketing by matching influencers with word-of-mouth content.
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