Sampling Period Research Articles

Herbicide paraquat dichloride augments the expression of the c-abl-noxa-apoptotic pathway, instigating ovarian atresia in edible fish, Channa punctatus.

Ovarian cells of animals undergo atresia to regulate egg numbers and their release. However, unrestrained atretic activity decreases the chances of oocyte maturity and further process, ultimately resulting in a reduced population. Edible fishes are a critical source of nutrition and it is required to regulate their population. The application of herbicides at fish production sites is a threat to their population by altering female reproductive activity. In concern to this, here, this 60-day study investigates herbicide paraquat dichloride (PD)-induced atresia in ovarian cells of Channa punctatus (C. punctatus). Further, 96-h LC50 of PD for C. punctatus was calculated as 58.40mg/L. At the end of each exposure period, an increase in intracellular ROS in blood cells and activities of SOD and CAT in ovary tissue were observed in PD-treated fish with increasing concentration. The frequency of micronuclei in blood cells subsequently increased with the highest PD concentration. A significant (p < 0.05) increase in the relative expression of target genes was observed at the 30th and 60th day of the sampling periods in the fish treated with the highest concentration of PD. The histological study confirmed the occurrence of atretic ovary cells in PD-exposed fish. From the results it can be concluded that PD enhances the uncontrolled death of ovarian cells and has consequences of impairing the ovary health and reproductive potential of fish, hence reducing the fish population.

Rhizobacteria Isolated from Amazonian Soils Reduce the Effects of Water Stress on the Growth of Açaí (Euterpe oleracea Mart.) Palm Seedlings

Euterpe oleracea Mart., also known for its fruit açaí, is a palm native to the Amazon region. The state of Pará, Brazil, accounts for over 90% of açaí production. Demand for the fruit in national and international markets is increasing; however, climate change and diseases such as anthracnose, caused by the fungus Colletotrichum sp., lead to decreased production. To meet demand, measures such as expanding cultivation in upland areas are often adopted, requiring substantial economic investments, particularly in irrigation. Therefore, the aim of this study was to evaluate the potential of açaí rhizobacteria in promoting plant growth (PGPR). Rhizospheric soil samples from floodplain and upland açaí plantations were collected during rainy and dry seasons. Bacterial strains were isolated using the serial dilution method, and subsequent assays evaluated their ability to promote plant growth. Soil analyses indicated that the sampling period influenced the physicochemical properties of both areas, with increases observed during winter for most soil components like organic matter and C/N ratio. A total of 177 bacterial strains were isolated from rhizospheres of açaí trees cultivated in floodplain and upland areas across dry and rainy seasons. Among these strains, 24% produced IAA, 18% synthesized ACC deaminase, 11% mineralized organic phosphate, and 9% solubilized inorganic phosphate, among other characteristics. Interestingly, 88% inhibited the growth of phytopathogenic fungi of the genera Curvularia and Colletotrichum. Analysis under simulated water stress using Polyethylene Glycol 6000 revealed that 23% of the strains exhibited tolerance. Two strains were identified as Bacillus proteolyticus (PP218346) and Priestia aryabhattai (PP218347). Inoculation with these strains increased the speed and percentage of açaí seed germination. When inoculated in consortium, 85% of seeds germinated under severe stress, compared to only 10% in the control treatment. Therefore, these bacteria show potential for use as biofertilizers, enhancing the initial development of açaí plants and contributing to sustainable agricultural practices.

Multi-Task Forecasting of the Realized Volatilities of Agricultural Commodity Prices

Motivated by the comovement of realized volatilities (RVs) of agricultural commodity prices, we study whether multi-task forecasting algorithms improve the accuracy of out-of-sample forecasts of 15 agricultural commodities during the sample period from July 2015 to April 2023. We consider alternative multi-task stacking algorithms and variants of the multivariate Lasso estimator. We find evidence of in-sample predictability but scarce evidence that multi-task forecasting improves out-of-sample forecasts relative to a classic univariate heterogeneous autoregressive (HAR)-RV model. This lack of systematic evidence of out-of-sample forecasting gains is corroborated by extensive robustness checks, including an in-depth study of the quantiles of the distributions of the RVs and subsample periods that account for increases in the total spillovers among the RVs. We also study an extended model that features the RVs of energy commodities and precious metals, but our conclusions remain unaffected. Besides offering important lessons for future research, our results are interesting for financial market participants, who rely on accurate forecasts of RVs when solving portfolio optimization and derivatives pricing problems, and policymakers, who need accurate forecasts of RVs when designing policies to mitigate the potential adverse effects of a rise in the RVs of agricultural commodity prices and the concomitant economic and political uncertainty.

How Important are Commodity Terms of Trade Shocks in Explaining Government Tax Revenue Fluctuations? Evidence from Ethiopia

Using a new database of commodity terms of trade and identifying country-specific commodity export and import price shocks separately, this article mainly aims to examine the importance of commodity export and import price shocks in explaining government tax revenue fluctuations using Ethiopia as an example over the sample period 1980–2019. This article employs a structural vector autoregressive model and forecast error variance decomposition analysis to address this objective. The results show that commodity export and import price shocks account for around 48% of government tax revenue fluctuations. While commodity export price shocks contribute to around 37% of fluctuations in government tax revenue, commodity import price shocks account for only 11% of government tax revenue fluctuations. These findings are discussed in terms of their policy implications. JEL Classification C32, F41, F44

Efficient removal of organic matter and nitrogen from municipal wastewater in multi-module biochar filters for onsite wastewater treatment

ABSTRACT Biochar is a promising material for wastewater treatment. This study assessed multi-module biochar filters (MmBFs) as onsite wastewater treatment systems (OWTSs), comprising movable modules filled with biochar to remove chemical oxygen demand (COD), nitrogen, phosphorus, and Escherichia coli (E. coli) in wastewater. The MmBF treats wastewater sequentially through six modules: three aerobic modules (M1-M3) for organic matter oxidation and nitrification, two anoxic modules (M4-M5) for denitrification, and an additional module (M6) for the removal of faecal bacteria using biochar and bark. The experiments ran for 381 days using three identical MmBF pilots with two distinct sampling periods, conducted under conditions relevant to OWTSs using municipal wastewater as influent. Water samples were taken from the influent, final effluent, and effluent of each module to evaluate the removal efficiency of organic matter, nitrogen, phosphorus, and E. coli. During the second sampling period, the results showed a 95 ± 2.1% removal of COD, along with a substantial removal of total inorganic nitrogen (71 ± 6.6%). However, phosphate removal was limited (3.4 ± 30.4%). E. coli removal decreased from 2.63 ± 0.93 log10 removal in the first sampling period to 1.8 ± 0.73 log10 removal in the second sampling period. In summary, the MmBFs showed promising potential in treating organic matter, nitrogen, and E. coli, making it an alternative option for OWTS. However, further exploration is needed to assess long-term performance, micropollutant removal, and biological activities. Design enhancements, especially for phosphorus removal are necessary.

Putting the Politics Into Corporate Political Activity: A Variance Decomposition Analysis of Firm–Government Interactions Across Political Contexts

Despite the wealth of theorizing about the relationship between business and government, research on corporate political activity (CPA) has yet to comprehensively consider how political context (e.g., party ideology and the degree of united or divided party government control) may shift the salience of how CPA materializes across industry-, firm-, and executive-level factors, which can shed light on the level of effects that appear to matter more (or less). To advance our understanding, we conducted a variance decomposition analysis on U.S. public firms (2001–2019), exploring the relative effect of each level on firm (lobbying expenditures and campaign contributions) and government actions (government contracts), and parsing our sample based on whether key government branches are Democrat- or Republican-controlled. We generally found that firm effects explain the most variance, followed by industry, while executive effects explain the least. However, this pattern shifts notably when considering political context across our sample period. As such, our findings have important implications for future CPA research and theorizing.

Balancing act: Examining the trade‐offs between regional convergence and economic growth in China's province managing county reform

AbstractThe study examines the relationship between regional convergence, economic growth and government hierarchies, with a specific focus on the province managing county (PMC) reform policy in China. The motivation for this research stems from the observation that a substantial portion of the increased inequality in China is attributable to disparities at the county level. This underscores the necessity for policies that address regional inequalities at the county level while simultaneously promoting sustained economic growth. We employ a time‐varying quasi‐natural experiment to explore how this reform has influenced regional convergence and economic growth within the sample period. The outcomes reveal that the PMC reform had a detrimental impact on regional convergence, hindering it by an average of 2.6%, while economic growth received a modest increase of 0.36%. The study also reveals notable heterogeneity in the effects of the reform, contracted disparities in western region, alongside exhibiting widened disparities and higher growth in eastern &amp; central region. The study also investigates the underlying mechanisms, finding that expenditures on basic provisions reduced, while county revenue and investment expenditures increased following the policy change. It proposes that the increased investment in capital expenditures stimulated economic growth but came at the cost of hindering regional convergence.

Performance evaluation of industry-education integration in higher education from the perspective of coupling coordination-an empirical study based on Chongqing.

The coupling coordination between higher education and regional industries is an effective way to enhance the performance of industry-education integration and an important driving force for promoting sustainable economic and social development. This article aims to evaluate the performance level of industry-education integration in higher education from the perspective of coupling coordination between industry and education, and to analyze its sustainable development trends. To achieve this, a framework for the industry-education complex system is constructed based on the theory of coupling coordination, and a performance evaluation model for industry-education integration is established. The "structure-conduct-performance" (S-C-P) analysis paradigm of industrial organization theory is used to design a performance evaluation indicator system, and the entropy weight method is applied to assign weights to the indicator system. Empirical research is conducted on Chongqing based on statistical data from 2000 to 2022. The results show that: (1) During the sample period, the construction effectiveness of industry-education integration in higher education in Chongqing is relatively significant, and the coordination level between regional industries and higher education continues to rise. (2) The orderly development level of the two subsystems of regional industries and higher education alternately rises, jointly promoting the continuous improvement of the performance level of industry-education integration, which is the main driving factor for performance improvement. (3) The stagnation of the coupling strength between regional industries and higher education is a key obstacle to further improving the performance of industry-education integration. Industry-education integration is a systematic project that should be promoted collaboratively from the perspectives of the regional industrial subsystem, higher education subsystem, industry-education complex system, and external environment to continuously enhance the performance level.

Fractional-Order Modeling of the Depth of Analgesia as Reference Model for Control Purposes

Little research has been carried out in terms of modeling and control of analgesia. However, emerging new technology and recent prototypes paved the way for several ideas on pain modeling for control. Recently, such an idea has been proposed for measuring the Depth of Analgesia (DoA). In this paper, that solution is further exploited towards obtaining a novel fractional-order model and dedicated controller for DoA. First, clinical data from patients undergoing general anesthesia are used to determine a commensurate fractional-order model of the skin impedance at each sampling period. Second, we provide a proof of concept indicating that fractional order changes due to variations in the infused opioid drug (Remifentanil). Third, a fractional-order model for DoA is developed correlating the changes in the pain index (as the output signal) and the Remifentanil infusion rate (as the input signal). Standard optimization routines are used to estimate the parameters. A database of 19 real patients is used. Lastly, a preliminary fractional-order controller is designed and tested in simulation for the 19 patients. The closed-loop simulation results correspond to the expected clinical outcomes.

The Impact of COVID-19 on the Value Relevance of Customer Satisfaction

This study examines the impact of COVID-19 on customer satisfaction and the value relevance of customer satisfaction. COVID-19 is an unprecedented pandemic that has changed all areas of business. Customer relations are one of the biggest paradigm shifts of this period. Companies have placed more attention on customer relations than on any other areas, and customer relations are an essential element in corporate sustainability. The value relevance directly represents the sustainability of corporations. It is very important for firms to retain their customers in the market, create a potential demand, and, thus, increase the firm value. We investigate whether companies financially benefit from customer relations. Employing the value relevance model, we regress firm value on the customer satisfaction scores with other control variables. We find that the customer satisfaction score has increased throughout the sample period, and that the value relevance of customer satisfaction has declined after the COVID-19 outbreak. Together, we interpret the results as indicating the impact of COVID-19 on the value relevance of customer satisfaction, especially the decreasing trends in value relevance. The results are robust even after controlling endogeneity and outliers. This study has several implications for practitioners and academia regarding the impact of COVID-19 on the value relevance of customer satisfaction.

Impact of Foreign Direct Investment on Green Total Factor Productivity: New Evidence from Yangtze River Delta in China

China has entered a period of high-quality development. As an important feature of high-quality development, green total factor productivity (GTFP) has attracted much attention. With the opening-up and economic globalization, the Yangtze River Delta, one of the strongest and most technological regions in China, has been attracting an increasing amount of foreign direct investment (FDI). This study investigates if FDI is conducive to GTFP under the constraints of specific resources and a specific environment, which has important practical significance for the utilization of FDI in the Yangtze River Delta and China. Through a literature review and sorting the current FDI in the Yangtze River Delta, the GTFP and its decomposition indicators of 27 cities from 2004 to 2019 are calculated based on their energy consumption and pollution. Using the fixed-effects model and threshold model of panel data, this study tests whether FDI promotes GTFP and whether a nonlinear impact of FDI on GTFP exists. It finds that (1) the GTFP of most cities in the Yangtze River Delta improved during the sample period, but their annual growth declined. Technology is the dominant factor affecting the growth of GTFP. (2) FDI in the Yangtze River Delta has increased, and the investment structure has improved, but the distribution among cities is uneven. (3) The scale and quality of FDI have a positive impact on GTFP, which supports the “Pollution Halo” hypothesis. Economics, education, networks, and trade openness can promote the growth of GTFP, while environmental regulation, government intervention, and industrialization have a negative impact. (4) The quality of FDI, economics, the industrial structure, the environmental regulation, and the internet are each a significant single threshold characteristic for the impact of FDI on GTFP. When one of these factors is lower than a certain threshold, FDI has less impact on GTFP. When one exceeds a certain threshold, FDI’s positive promotion effect on GTFP significantly improves. Based on the analysis, this study offers some suggestions. The government should improve the FDI selection mechanism based on realities, make appropriate environmental regulatory policies, strengthen the construction of networks, and improve the “Internet+” effect on productivity.

ENHANCED MODEL-FREE PREDICTIVE CONTROL FOR VOLTAGE SOURCE INVERTERS USING AN ADAPTIVE OBSERVER

In this paper, a free model predictive control based on the active vector execution time (AVET-MFPC) using an adaptive observer is proposed for two-level voltage source inverters. The traditional model-free predictive control (MFPC) uses the sampling period to select one voltage vector for all candidate vectors according to the minimizing cost function principle. With the proposed control, two vectors are selected at one sampling period. The first vector is an active vector that uses the execution time of the active vector to select it, while the second one is a zero vector as it is applied after the active vector. The execution time is calculated using the ultra-local model (ULM) equation. In the traditional MFPC, the factor in the ULM is chosen with approximate values ranging between ±50 % of the nominal value. This paper proposes an adaptive sliding mode observer (ASMO) with an improved design to observe the variation of this factor, especially in case of mismatch parameters and during a step change in the reference signal. Combining the proposed ASMO observer and the AVET-MFPC controller gives faster system response, good tracking results, and less computational burden. Finally, the effectiveness of the proposed control model is approved and confirmed under various conditions, as well as the simulations carried out and the results obtained.

Pengaruh Profitabilitas dan Leverage Terhadap Kualitas Laba dengan Kepemilikan Manajerial Sebagai Variabel Moderasi

This study aims to be able to test profitability and leverage on profit quality with managerial ownership as a moderation variable. This study used a sample of 78 manufacturing companies listed on the Indonesia Stock Exchange (IDX) for the 2021-2022 period using the purposive sampling method. This study uses multiple linear regression analysis techniques and Moderate Regression Analysis (MRA) with IBM SPSS Statistic tools. The results of this study empirically prove that leverage affects the quality of profits. As for profitability, it has no effect on the quality of profits and managerial ownership cannot moderate the influence between profitability and leverage on the quality of profits. Further research is suggested to increase the number of company samples and extend the period of the research sample.

Population Dynamics of the Mite Varroa destructor in Honey Bee (Apis mellifera) Colonies in a Temperate Semi-Arid Climate.

This study aimed to analyze the population dynamics of the mite Varroa destructor in honey bee (Apis mellifera) colonies in a temperate semi-arid climate in Mexico. Ten colonies homogeneous in population, food stores, and levels of mite infestation were used. The mite infestation rate in brood and adult bees, total number of mites, daily mite fall, brood and adult bee population, and food stores were determined periodically for 10 months. There was a significant effect (p < 0.05) of sampling period on the population of V. destructor in adult bees, brood, total mite population, and daily fallen mites. The total mite population increased by 26% on average per colony. The increase in brood amount reduced the mite infestation rate in adult bees, and the opposite occurred when the brood decreased. Monitoring V. destructor populations by recording fallen mites is more reliable than determining mite infestation rates in bees, as mite fall has a dynamic pattern similar to that of the total mite population. The best period to apply an acaricide treatment in the region of study is between November and December because most mites were in the phoretic phase, since there was less brood in the colonies compared to other times.

Plastics at an Offshore Fish Farm on the South Coast of Madeira Island (Portugal): A Preliminary Evaluation of Their Origin, Type, and Impact on Farmed Fish

Plastic pollution is a global problem affecting all ecosystems, and it represents most of the marine litter. Offshore aquaculture is a sector particularly vulnerable to this issue. To investigate this concern, the present study employed videography to monitor macroplastics at an offshore fish farm on Madeira Island (Portugal) and analysis of fish gut content to evaluate macroplastic ingestion by farmed sea bream Sparus aurata. Our analysis revealed that the majority of identified plastic debris originated from domestic use (66.66%) and fisheries/aquaculture activities (24.99%). While the number of dead fish suitable for sampling was limited (1.05% of the total mortality), macroplastic debris ingestion was identified in 5.15% of the total mortalities and reported for the first time in species in offshore farming conditions. Fish ingested fragmented plastic sheets, with the amount positively correlated with fish weight (r = 0.621, p = 0.031, n = 12). Notably, the stretched length of these fragments exceeded 50% of the standard length of most fish. Inconsistencies were observed in the number of samples collected per cage and per week. To ensure robust results, these discrepancies should be rectified in future studies. Additionally, extending the sampling period to encompass all seasons would be beneficial for a more comprehensive understanding of seasonal variations in plastic occurrence.

A comparative study of optical and size properties of dissolved organic matter in the lower Mississippi River and Pearl River

Monthly water samples were collected from the lower Mississippi and Pearl Rivers between January 2009 and August 2011 to investigate the heterogeneity in the dynamic variations of dissolved organic carbon (DOC), colloidal organic carbon, chromophoric and fluorescence dissolved organic matter (CDOM and FDOM), PARAFAC-derived fluorescent components, and other optical properties including spectral slope, specific UV absorbance (SUVA), and fluorescence indices between the two contrasting river systems. The lower Mississippi River exhibits relatively lower concentrations of DOC (306 ± 41 μM C) and CDOM (27.9 ± 5.7 m−1 at 254 nm), featuring lower aromaticity (indicated by SUVA254) and apparent molecular weight (or higher spectral slope) with weak seasonal variability. The Pearl River, in contrast, has elevated levels of DOC (537 ± 212 μM C) and CDOM (66.4 ± 31.4 m−1), characterized by higher aromaticity, higher molecular weight, and significant seasonality, primarily originating from soil-derived allochthonous sources. The abundance of the >1 kDa colloidal DOC was, on average, 58 ± 3 % of the bulk DOC in the lower Mississippi River and 68 ± 6 % in the lower Pearl River. The >1 kDa high-molecular weight DOM (HMW-DOM) consistently had lower spectral slope and biological index (BIX) values, but higher humification index (HIX) values compared to both bulk DOM and low-molecular-weight DOM (LMW-DOM) counterparts. These trends could be representative of other similar large and small rivers. Four PARAFAC-derived fluorescent components (three humic-like and one protein-like) were identified for both rivers. A positive correlation between discharge and terrestrial humic-like fluorescent components indicated their dominant allochthonous sources, while the protein-like component decreased with increasing discharge, consistent with its autochthonic source and a dilution effect during high flow seasons. The occurrence of large flood events during the sampling period contributed to large DOC pulses, with DOM of higher aromaticity and HMW-DOM. This has important implications for coastal ocean ecosystems, which are increasingly impacted by river flooding events under changing climate conditions. Our results also provide an improved understanding of DOM dynamics in two representative rivers and establish a baseline dataset for future studies to assess changes in sources and composition of DOM and their impacts on the coastal ocean in response to climate, hydrological, and anthropogenic influences.

Development of an external system for monitoring the couch speed in radiotherapy using continuous bed movement.

Total body irradiation before bone marrow transplantation for hematological malignancies using Radixact, a high-precision radiotherapy machine, can potentially reduce side effects and the risk of secondary malignancies. However, stable control of couch speed is critical, and direct assessment methods outlined in quality assurance guidelines are lacking. This study aims to develop a real-time couch speed verification system for the Radixact. The developed system used a linear encoder to measure couch speed directly. Accuracy was verified via a linear stage, comparing measurements with a laser distance sensor. After placing a phantom simulating the human body on the Radixact couch, the couch speed was verified using predefined speed plans. Operating the linear stage at 0.1, 0.5, and 1.0mm/s revealed that the maximum position error of the developed verification system compared to the laser distance sensor was nearly equivalent to the distance resolution of the system (0.05mm/pulse), with negligible average speed error. When the Radixact couch operated at 0.1, 0.5, and 1.0mm/s, the values obtained by the verification system agreed with the theoretical values within the sampling period (0.01s) and distance resolution (0.05mm). The verification system developed provides real-time monitoring of the speed of the Radixact table, ensuring treatment effectiveness and patient safety. It would guarantee the couch speed's soundness and contribute to the "visualization" of safety.

Quantile connectedness among fintech, carbon future, and energy markets: Implications for hedging and investment strategies

This study proposes a novel framework to explore the quantile connectedness among fintech, carbon future, and energy markets with implications for hedging and investment strategies. We aim to construct portfolio strategies for extreme market conditions based on the results of quantile connectedness to address the complex price fluctuations in the energy markets. Using the daily data from January 4, 2017, to March 6, 2023, we find that (i) carbon future and crude oil are the net receivers, while fintech and clean energy are the net contributors. However, the net spillover direction of fintech, carbon futures, and energy markets change frequently under extreme market conditions; (ii) the COVID-19 pandemic and Russia-Ukraine conflict significantly enhance connectedness across all quantile levels; (iii) the sample period is dominated by the lower quantile connectedness, indicating that investors react more strongly to bad news. Furthermore, the result of portfolios shows that, compared to normal market conditions, the dynamic investment weights of minimum connectedness (MCOP) exhibit greater volatility under extreme market conditions. This highlights the differences in portfolio adjustments across different market conditions. In addition, the result shows that the minimum connectedness and minimum correlation portfolio have a greater cumulative return than the minimum variance portfolio. The analysis based on the Sharpe ratio shows that in extreme market conditions, carbon futures and fintech can serve as effective hedging tools for the energy markets. Robustness tests further confirmed our conclusions. Our results have positive implications for decision-makers and investors about risk management and diversified portfolio selection.

Unraveling atmospheric mercury dynamics at Mauna Loa through the isotopic analysis of total gaseous mercury

Our investigation seeks to uncover the intricate nature of mercury dynamics in the free troposphere through analysis of the isotopic composition of total gaseous elemental mercury (TGM) at the high altitude Mauna Loa Observatory (MLO, 3397 m) in Hawaii, USA. By focusing on this unique site, we aim to provide essential insights into the behavior and cycling of mercury, contributing valuable data to a deeper understanding of its global distribution and environmental impacts. Forty-eight hours of TGM sampling from January to September 2022 revealed significant variations in δ202Hg (−1.86 % to −0.32 %; mean = −1.17 ± 0.65 %, 2 SD, n = 34) and small variations in Δ199Hg (−0.27 % to 0.04 %; mean = −0.13 ± 0.14 %, 2 SD, n = 34) and Δ200Hg (−0.20 % to 0.06 %; mean = −0.05 ± 0.13 %, 2 SD, n = 34). During the sampling period, GEM was negatively correlated with gaseous oxidized mercury (GOM). However, the GOM/GEM ratio was not −1, suggesting that GEM oxidation and subsequent scavenging occurred previously. The δ202Hg isotopic compositions of TGM at MLO were different from those of reported values of high-altitude mountains; the δ202Hg of TGM at MLO was lower than the isotopic ratios that were obtained from other mountain regions. The unique atmospheric conditions at Mauna Loa, with (upslope winds during the day and downslope winds at night, likely result in the) possibly mixing of GEMs from terrestrial (and possibly oceanic GEM emission) sources with and tropospheric sources, influencing and affect the isotopic composition. During the late summer to early fall (September 14–28), negative correlations were found between relative humidity and GOM and between particle number concentrations and Δ199Hg, indicating the gas-to-particle partitioning of the atmospheric mercury during this period. This study will improve our understanding on mercury dynamics of marine origin and high altitudes and shed light on its complex interactions with environmental factors.

Does environmental regulation truly enhance corporate green environmental investment? Evidence from the supervision of independent directors in listed companies.

With the increasingly prominent environmental issues in China, the government and citizens alike have intensified their focus on corporate investments in green environmental protection. Nevertheless, as government regulations become more stringent, there is substantial debate over whether environmental regulatory policies can consistently encourage listed companies to increase green environmental investments. Simultaneously, independent board supervision plays a crucial role in promoting the compliance and sustainability of listed companies regarding environmental protection. This paper selected a sample of 246 Chinese listed companies from 2010 to 2019, and used a fixed effects model to examine the impact of environmental regulation on the environmental investment of listed companies in China. Moreover, we used a mediation effect model to analyze the role of independent director supervision in influencing the relationship between environmental regulation and companies' green environmental investment. Additionally, we discuss the heterogeneous impact of environmental regulations on corporate environmental investments. Our findings are as follows: first, during the sample period, the tightening of environmental regulations significantly reduces the growth of environmental investment among the studied firms. As government environmental regulatory policies gradually intensify, the negative impact on environmental investments by listed companies becomes increasingly evident. Second, independent directors help alleviate the adverse impacts of environmental regulations on the environmental investment levels of listed companies. This suggests that the inclusion of independent directors in board governance plays a role in assessing government environmental regulatory policies and overseeing corporate decisions related to environmental investment. Lastly, the heterogeneity analysis indicates that environmental regulation significantly negatively impacts the environmental investment of listed companies in pollution-intensive industries and those located in the western regions. Furthermore, environmental regulatory policies impose greater constraints on the environmental investments of small-sized listed companies compared to their large-sized counterparts.