Nitrate denitrification rate response to temperature gradient change during river bank infiltration.

Nitrate attenuation during river bank infiltration is the key process for reducing nitrogen pollution. Temperature is considered to be an important factor affecting nitrate attenuation. However, the magnitude and mechanism of its impact have not been clear for a long time. In this study, the effects of temperature and temperature gradient on the nitrate denitrification rate were investigated via static batch and dynamic soil column simulation experiments. The results showed that temperature had a significant effect on the denitrification rate. Temperature effects were first observed in denitrifying bacteria. At low temperatures, the microorganism diversity was low, resulting in a lower denitrification rate constant. The static experimental results showed that the denitrification rate at 19 °C was approximately 2.4 times that at 10 °C. The dynamic soil column experiment established an exponential positive correlation between the nitrate denitrification decay kinetic constant and temperature. The affinity of denitrifying enzymes for nitrate in the reaction substrate was ordered as follows: decreasing temperature gradient (30 °C → 10 °C) > zero temperature gradient (10 °C) > increasing temperature gradient condition (0 °C → 10 °C). This study provides a theoretical basis for the biogeochemical processes underlying river bank infiltration, which will help aid in the development and utilization of groundwater resources.

Soil ecoenzyme activities coupled with soil properties and plant biomass strongly influence the variation in soil organic carbon components in semi-arid degraded wetlands.

Wetland degradation can induce alterations in plant biomass, soil properties, and soil ecoenzyme activities, consequently influencing soil organic carbon components. Despite extensive investigations into the relationships among plant characteristics, soil properties, and soil organic carbon components, the enzymatic mechanisms underlying changes in soil organic carbon components, particularly the impact and contribution of ecoenzyme activities, remain poorly understood. This study compared the soil organic carbon components at a depth of 0-20 cm in wetlands in the semi-arid western Songnen Plain under different degradation levels and explored plant biomass, soil properties, and soil ecoenzyme activities. The results showed that the soil total organic carbon, labile organic carbon, and recalcitrant organic carbon contents in the degraded wetlands were generally lower than those in the non-degraded wetlands. Furthermore, the soil nutrient contents and soil ß-1,4-glucosidase, L-leucine aminopeptidase, and acid phosphatase activities were also lower in the degraded wetlands than in the non-degraded wetlands. Vector analysis of enzymatic stoichiometry revealed that wetland degradation did not increase microbial carbon limitation. The soil organic carbon components showed significant positive correlations with plant biomass, soil water content, soil total nitrogen, soil total phosphorus, as well as soil ecoenzyme activities. Variation partitioning analysis revealed that plant biomass, soil properties, soil ecoenzyme activities collectively accounted for 78.5 % variation in soil organic carbon components, among which plant biomass, soil properties, soil ecoenzyme activities, and their interactions explaining 4.2 %, 8.0 %, 7.9 %, and 24.5 % of the variation, respectively. Therefore, the impact of soil ecoenzyme activities and soil properties on soil organic carbon component changes was greater than that of plant biomass, with the interaction of these three factors playing a crucial role in soil organic carbon formation. This study provides a theoretical basis for scientifically evaluating the carbon sink function of degraded wetland soil and preserving the wetland soil carbon pool.

Coping with the liquidity crisis: a new dynamic quota readjustment scheme for carbon markets.

Because of insufficient liquidity, prices in the carbon market are more vulnerable to unexpected events, for which the impact duration lasts longer than that of the general market. The root reason for this phenomenon lies in the irrationality of quota distribution. The existing quota adjustment schemes and policies, e.g., the market stability reserve (MSR) and some recent adjustment measures, have poor timeliness and effectiveness, which has increased the risk of market crashes. Using the Hidden Markov Model (HMM), this paper develops a new dynamic quota adjustment scheme that can rapidly reduce the risk of quota supply by bridging quota price and quantity with price feedback as a response signal. To achieve this, we integrated the HMM algorithm and a two-step quota adjustment model by setting price thresholds and then connected the quota adjustment transition matrix and historical quota price. By comparing the MSR from 2013 to 2018, our scheme will help mitigate risks in quota price because the HMM can show the actual impact of price feedback on quota adjustment with merits of steady quota price and timely supply optimization. Moreover, our scheme, which recalculates the transition matrix, can be applied in other mature carbon markets.

The influence of COVID-19 on grid parity of China's photovoltaic industry.

With the more efficient involvement of both technology and policy factors in China's whole industry-chain, the year 2020 is a key period for photovoltaic (PV) industry to achieve grid parity. In this context, COVID-19 may trigger a certain time-delay in new installed PV projects, thereby bringing an uncertain influence on the whole PV industry. To forecast the influence degree and influence cycle of COVID-19 on PV industry, this paper firstly clarifies the key features of epidemic situation as well as the basic rule of such pandemics' transmission along industry-chain. Then this paper constructs a system dynamics model targeting at cost accounting of PV power generation under the influence of COVID-19 and thus forecasts the variation rules, superposition effects and influence cycle of levelized cost of energy (LCOE) of PV power generation and the operations cost of each sub-system. Empirical results show that PV industry has a lag response to the COVID-19 for 1 quarter and periodic response for 4 quarters, which is mainly embodied in the rise of short-term production cost. At the same time, the influence of COVID-19 on the upstream firms of PV industry is stronger than that on downstream firms. With the gradual recovery of whole industry-chain, LCOE of PV power generation will rapidly return to the previous expected level of grid parity by the end of 2020.

Intervention factors associated with environmental stressors resulting from cross-provincial transfers by coal resource-based enterprises.

The environmental stressors associated with the cross-provincial transfer of coal resource-based enterprises (CREs) have become a critical concern for the green, sustainable, and high-quality development of resource-rich areas in central and western regions. This study referred to socioeconomic statistics and carried out an interview survey, literature review, and systematic analysis to clarify the mechanism underlying environmental stressors arising from the cross-provincial transfer of CREs. The intervention factors associated with such environmental stressors were identified, and the study conducted an empirical analysis of relevant data related to the coal-resources industry in three central and western provinces in China for the period 1997-2016. Research findings: (1) The intensity ranking of the influencing factors associated with environmental stressors caused by cross-provincial transfers of CREs has certain rules. The 'level of the enterprise's investment in environmental protection' is the weakest, the 'enterprise's development mode level' is slightly stronger, the 'enterprise scale' is stronger, and 'environmental regulation' is the strongest. (2) Stricter endogenous and exogenous policy regulations for environmental governance in rich coal resource-based regions are associated with weaker negative externalities in respect of resource development and the intensity of stressors. (3) Larger CREs are associated with a better green mining capacity, environmental repair cost advantages, social constraints, self-discipline, and thus, a weaker stress effect. (4) CREs that adopt more superior modes of development that focus on the utilization of the 'three wastes' are associated with a weaker stress effect. (5) The higher the level of investment by CREs in environmental protection technology, facilities, and equipment, the weaker the stress effect. The conclusions of the study can provide a theoretical basis to assist the Chinese government to develop relevant regulations to control inter-provincial transfers by CREs and to thereby diminish environmental stressor effects.

Does the promotion pressure on local officials matter for regional carbon emissions? Evidence based on provincial-level leaders in China.

This paper constructs data from 30 provinces in mainland China from 1997 to 2016 and mainly adopts panel data fixed effects models to investigate how the promotion pressure on local officials affects regional carbon emissions. Our empirical results show that the relationship between the promotion pressure on local officials and regional carbon emissions has a dynamic evolution characteristic during our research period. Specifically, the promotion pressure on local officials is positively associated with regional carbon emissions before 2009; however, this relationship weakened after China's carbon emission regulatory policies were strengthened in 2010. Furthermore, our heterogeneity analysis results show that the effect of promotion pressure on regional carbon emissions is moderated by the regional industrial structure, the economic development level, regional innovation capability, the tenure of officials and the age of officials. The conclusions of this study are helpful for understanding the driving factors of regional carbon emissions from the political economy perspective, and they also have implications for the formulation of performance evaluation and carbon emission reduction policies.

The impact of production factor distortion on total factor energy productivity: insight from China's region level.

Clarifying the impact of production factor distortion on total factor energy productivity (TFEP) is a key approach to promote production greenization at the region level. To achieve it, this paper develops a theoretical model to bridge production factor distortion and TFEP with China's four regions as the investigated object based on provincial data from 2003 to 2017. Empirical results show that there exist obvious production factor distortions in China's four regions, and such distortions significantly negatively influence the volatility of TFEP as a whole. Specifically, the allocation of production factors including skilled labor in Eastern and Northeastern China as well as capital input in equipment purchase sector in Central and Western China can significantly improve regional TFEP. What's more, distortions of quite a few production factors including skilled labor in Central and Western China, unskilled labor in four regions, and capital input in some industrial sectors in Central and Northeastern China can all hinder the growth of regional TFEP. Therefore, in order to improve regional TFEP in China and reduce factor distortions, the government need to focus more on the input structure of these production factors that have negative impacts on TFEP, and then promote the institution reform towards the high-quality economy growth mode.

The antecedent and performance of environmental managers' proactive pollution reduction behavior in Chinese manufacturing firms: Insight from the proactive behavior theory.

This paper contributes to our understanding of how to improve manufacturing firms' green operations underpinned by the proactive behavior theory. Chinese manufacturing firms are focused on because of their significant impact on global climate change and distinctive governance structure. Specifically, we survey 155 highest-level environmental managers (EMs) in these firms who have an ultimate decision-making power on environmental issues, and investigate the antecedents and consequence of their proactive pollution reduction behavior (PPRB). Through identifying the psychological motivation implied in EMs' environmental management behavior, we find that both EMs' role breadth self-efficacy (including in-role self-efficacy and extra-role self-efficacy) and felt responsibility (including felt responsibility establishment and felt responsibility coordination) can improve their PPRB. Further, available resources in firms only positively moderate the impact of extra-role self-efficacy on PPRB, and incentives from external stakeholders only moderate the impact of felt responsibility establishment on PPRB. Our empirical results also confirm that PPRB can improve corporate operational performance, strategic competitiveness, and environmental performance, but a higher level of PPRB's performance comes more from the driving force of PPRB's antecedents rather than PPRB itself.