Coastal water quality (CWQ) and the reduction of environmental emissions (EE) are two of the most critical priorities for sustaining ecosystems and the viability of human habitats (Bierman et al., 2011; Kai et al., 2024). China, despite being the 6th largest nation in terms of total water resources, ranked the 13 most water-scarce nations globally, with per capita water availability falling below 300 m³ (Liu et al., 2021). The overexploitation of both surface and groundwater, combined with the gradual degradation of water quality, has compounded water security challenges, impeding both economic growth and ecological recovery (Gao et al., 2020). Over the past decade, China’s surface water quality has been clustered as poor and severely degraded due to the rapid pace of economic growth. The ecosystems, public health, soil quality, and environment have all suffered greatly as a result of this degradation (He and Perloff, 2016). Recognizing the significance of surface water quality, the Chinese government has undertaken numerous efforts through various campaigns and initiatives aimed at improving this indicator. As a result, notable achievements in water quality have been realized. In 2022, the percentage of CWQ meeting the standard Grade I and II reached 81.9%, an increase of 0.6% points compared to 2021. Specifically, the area matching the Grade I standard declined by 4.9%, while the area satisfying the Grade II grew by 5.5%. The proportion of CWQ below Grade IV dropped by 0.7 percentage points to 8.9%, with inorganic nitrogen and active phosphate remaining the primary pollutants (Ministry of Ecology and Environment People’s Republic of China, 2022).

In terms of emissions, in 2022, China emitted 12.7 billion metric tons of carbon dioxide (CO₂) (Statista, 2024), accounting for 32,9% of global emissions. As part of its approach to combat air pollution and decrease carbon footprint, China has methodically implemented a range of carbon neutrality campaigns and the emissions trading scheme (Du et al., 2022). Research has demonstrated that these policy measures have been essential in enabling China to reach its goal of reducing its carbon footprint. China’s “National Comprehensive Demonstration of Energy Saving and Emission Reduction Fiscal Policy” was studied using a lagged dif-ference-in-differences model to investigate the comprehensive effect of green fiscal policy (GFP) on the reduction of CO₂ and other pollutants (Fan and Liang, 2023). They indicated that GFP could considerably mitigate CO₂ and the more pronounced synergistic effect was recognized in cities experiencing lower fiscal pressure. Another study expanded policy discussions by examining the influences of energy generation and GFP measures on the exhausted CO₂ of BRICS nations (Ma et al., 2023). Based on the study’s findings, it can be observed that government spending exacerbated energy consumption and increased emissions. Li et al. (2023) analyzed the influence of GFP and stringent regulations on consumption-based CO₂ (CCO₂). The findings indicated that economic development, nonrenewable energy, and government spending exacerbated CCO₂, whereas tax revenue, the stringency of environmental policies, and renewable energy helped reduce CCO₂. This provides critical evidence for a more detailed understanding of how economic development impacts energy decomposition and CCO₂ emissions across different quantiles. Consequently, it supports the integration of renewable energy development policies with economic growth strategies to mitigate negative effects on CCO₂ emissions.

Tourism (TR), as one of the major economic drivers, contributes significantly to environmental deterioration, negative social and cultural effects, and the fragmentation of natural habitats (Lukoseviciute and Panagopoulos, 2021). Furthermore, coastal sites, which are frequently at the forefront of the TR sector, face the brunt of water pollution caused by improper disposal of solid trash and food residues. This pollution manifests as eutrophication, in which nutrient overloads, mainly nitrogen and phosphorus, cause algal blooms, resulting in oxygen depletion in coastal waters and harming marine biodiversity. The link between TR-induced emissions and water pollution puts additional strain on ecosystems, particularly in coastal places that are already sensitive to the variations of climate change. The massive flood of visitors not only increases demand for food and energy, resulting in higher carbon emissions, but it also hastens the deterioration of water quality due to increasing rubbish production. For example, cruise liners, a major means of transportation, are renowned for releasing massive amounts of untreated sewage and greywater directly into the ocean, adding to coastal ecosystem degradation (Lloret et al., 2021; Vu-Thi-Minh et al., 2024). This not only upsets the natural equilibrium of marine habitats but also poses long-term dangers to the livelihoods of coastal people, tying economic and ecological interests together in a web of interdependence. Xu et al. (2024) identified the effects of fintech (FT), TR, and investment in natural resources on environmental sustainability in leading tourist arrival countries. This study successfully identifies the inverse impact and quantifies the effects of FT and TR on CO₂ across different quantiles. Additionally, it recommends the adoption of CO₂ emission standards for the TR and hospitality sector to ensure that companies within this industry are compelled to transition toward sustainable practices.

FT involves the integration of artificial intelligence applications, blockchain, and other robust information technologies into the field of finance, which is currently transforming financial services (Cheng et al., 2023). In addressing interwoven challenges of CO₂ emissions, the role of FT as a financial enabler for sustainable environmental practices becomes increasingly apparent (Leng et al., 2024). By facilitating carbon credit trading systems and enabling decentralized financing for clean energy projects within the TR industry, FT can support the reduction of emissions at a systemic level. At the same time, FT innovations in traceability and transparency of food production and waste streams can bridge the gap between TR operators and sustainable resource management, fostering a more resilient and eco-friendlier TR ecosystem. FT has been increasingly recognized as a supportive and driving mechanism for promoting renewable energy and biomass energy sources (Bui-Duy et al., 2023). The intersection of FT with environmental sustainability thus offers a promising avenue for tackling the complex dynamics between TR, water pollution, and emissions, ensuring a balanced approach to economic growth and environmental stewardship. The National Development and Reform Commission of China and the Ministry of Finance jointly released a financial policy on energy conservation and pollution elimination, which promised to help pilot city governments better integrate financial policies for energy generation and pollution elimination while also making it easier to achieve sustainable development objectives (Miao et al., 2023).

In this study, we examine the factors, including GFP, FT, and TR, for some reasons. First, GFP integrated with FT can fund sustainable TR projects, providing opportunities for small and medium-sized enterprises in the TR sector to access advanced capital and technology, potentially leading to positive environmental impacts. Second, FT reduces transaction and monitoring costs associated with GFP implementation, enabling TR businesses to more effectively meet sustainability requirements. Third, the simultaneous consideration of these three factors remains underexplored in previous studies.

Our review highlights some gaps in the literature. First, studies exploring the relationship between FT and CWQ are lacking. Second, while some studies examined the impacts of green fiscal policies (GFP) and TR on CO₂ emissions across quantiles, these studies have not extended their scope to CWQ and do not consider FT’s simultaneous effects on CWQ. Consequently, the government and local authorities may lack an accurate assessment of whether the current policies are more effective in addressing air pollution or marine water pollution, or the extent of their effectiveness under varying levels of pollution—low, moderate, or high. This is crucial for evaluating whether resources allocated to these policies are being used efficiently or wasted.

Another gap can be recognized in considering detailed insights into short-term heterogeneity, as the AMG (augmented mean group) and CCEMG (common correlated effect means group) methods rely on assumptions of uniform short-term dynamics across units and group-averaged effects. Moreover, previous methods are well-suited for normal distributions, whereas our dataset exhibits asymmetry. By employing MMQR, we effectively address this asymmetry, mitigate the impact of outliers, better capture nonlinear relationships, and handle cross-sectional dependence (CSD) with greater flexibility. Consequently, the effects of explanatory variables on the dependent variable across different quantiles can be comprehensively examined. Given that GFP, FT, and TR do not always exhibit linear impacts on CO₂ emissions and CWQ, the utilization of MMQR provides valuable insights for developing more precise and targeted policy interventions.

This paper aims to investigate the asymmetric relationship between three independent factors—GFP, TR, and FT—and two environmental indicators, namely, CO₂ emissions and CWQ. Also, we explore whether the current GFP policies and FT activities are more effective in addressing air or marine water pollution, and which environmental indicator is more adversely affected by TR activities. Additionally, their effectiveness is investigated corresponding to varying levels of pollution. The study makes some novel contributions. First, we examine whether the impacts of these independent factors on the environment are positive or negative. Second, we investigate the extent of their influence on the two environmental indicators across different quantiles. Third, based on our findings, we identify the key measures necessary for the sustainable implementation and management of GFP, TR, and FT to foster more positive environmental outcomes. This paper is structured as follows. Section 2 begins with a fundamental theoretical foundation, develops the research procedures, and establishes hypotheses. Section 3 describes the research methodologies, and analyzes the data. The discussions of the findings are implemented in Section 4. Finally, Section 5 highlights the theoretical and practical significance. Also, the limitations and directions for future research are discussed and suggested.

By enabling sustainable practices and prohibiting environmentally destructive actions, the GFP can accelerate carbon neutrality. Governments can shift economic activity to low-carbon alternatives by introducing policies such as carbon taxes, renewable energy subsidies, and green infrastructure projects. These regulations stimulate not just the use of clean technologies, but also the reduction of greenhouse gas emissions by industries and consumers (Fan and Liang, 2023). Furthermore, GFP can enhance public awareness and engagement in sustainability initiatives, leading to a collective reduction in carbon footprints across various sectors (Benkhodja et al., 2023). It can employ environmental taxes and fees as penalties to raise the cost of emissions for polluting businesses, thereby internalizing the external costs associated with environmental damage (Fan and Liang, 2023). One significant impact of GFP is its potential influence on the renewable energy sector (Zhang et al., 2022). Alongside monetary policy, tight fiscal policies have been identified as effective measures for mitigating CO₂ emissions (Chishti et al., 2021). Numerous studies also advocate for governments to adopt policies that impose higher taxes on petroleum and major polluting sources while increasing subsidies for renewable energy industries and green technologies (Li et al., 2024; Ran et al., 2024). One of GFP’s tools, environmental taxes, has garnered significant attention in Europe and other developed economies as a means to encourage investment in renewable energy. In developing countries, 78.64% of environmental tax revenue comes from energy taxes, which account for 6% of total tax revenue and 4% of GDP (Orlov and Aaheim, 2017). Current research emphasizes that to promote investment in environmentally friendly energy sources, governments must impose taxes on activities that harm the natural environment. Such environmental taxes are expected to boost investment in renewable energy, thereby enhancing ecological efficiency.

Based on previous literature, we develop the below hypothesis.

Hypothesis 1

GFP plays an essential role in contributing to EE.

In terms of the CWQ, GFP has been implemented in a diversified manner. Measures such as subsidies for eco-friendly technologies, taxes on pollution-intensive activities, and investments in waste management and water treatment infrastructure can effectively decrease the discharge of pollutants into coastal areas. By encouraging industries and municipalities to adopt cleaner technologies and practices, GFP enables the reduction of coastal water pollution, including runoff from agriculture, industrial discharges, and untreated sewage (Wang et al., 2022). Additionally, these policies can incentivize the protection and restoration of coastal ecosystems, further enhancing water quality and contributing to the overall health of marine environments (Zhang et al., 2021). The GFP is believed to be an indirect regulatory tool to support the monitoring, management, and control of environmental impacts in the Yucatan Peninsula (Mexico) (Vidal-Hernández et al., 2021). After decades of economic development accompanied by severe water quality degradation, the Chinese government has implemented green fiscal policies in various forms to improve water quality. To evaluate the achievement of “10-Point Water Plan”, Zhou et al. (2021) indicated that this policy created a significantly positive impact on industrial water quality, as evidenced by an analysis of industrial water pollution levels before and after the policy’s adoption. Using the comprehensive feasible generalized least squares method, Jiang and Li (2021) argued that the promotion-driven motivations of local officials significantly influenced marine environmental degradation. Although GFP was not directly addressed, they also indicated that local authority incentives positively impact marine ecosystems. Naturally, the instruments of GFP do not have uniform impacts. This heterogeneity reduces the effectiveness of environmental tax/subsidy policies in surrounding contexts. Wu S et al. (2021) examined the impact of four types of firm heterogeneity and three methods of processing social norm information on the effectiveness of environmental tax/subsidy policies. The authors concluded that informational nudges can enhance outcomes even in the presence of significant heterogeneity within the policy environment. These arguments in the literature reinforce the existence of a research gap in examining the effectiveness of GFP on CWQ across different quantiles.

Based on previous literature, we develop the below hypothesis.

Hypothesis 2

GFP plays an essential role in contributing to CWQ.

In terms of EE, research has demonstrated that the TR industry contributes notably to environmental degradation on a global scale. TR activities, including transportation, accommodation, and excessive consumption, rely heavily on fossil fuels or electricity (UN Tourism, 2024). The amount of CO₂ emissions that TR generates serves as a key metric for evaluating its environmental impact. This topic has been central to research on the interaction between humans and the environment within the TR sector in the 21st century. Gössling (2000) pioneered a method for estimating CO₂ emissions specifically associated with TR. Since then, this issue has garnered increasing attention. TR heavily relies on energy, with the majority being derived from fossil fuels. The combustion of these fuels results in the emission of various greenhouse gases, predominantly CO₂. The TR industry generates carbon emissions through both direct and indirect channels (Ullah et al., 2022). Direct emissions arise from the energy consumption directly associated with the TR system, while indirect emissions stem from embodied CO₂ linked to the energy use involved in producing intermediate goods and services by TR-related businesses. The volume of carbon emissions from the TR sector serves as a crucial indicator for evaluating its environmental impact (Mishra et al., 2022). Ullah et al. (2022) demonstrated that TR contributes to CO₂ emissions through both positive and negative shocks by employing nonlinear ARDL estimations.

Based on relevant literature, we develop the following hypothesis.

Hypothesis 3

TR plays an essential role in contributing to EE.

The hypothesis regarding the impact of TR on CWQ posits that increased TR activities are likely to harm coastal ecosystems. As TR grows, particularly in coastal regions, the demand for infrastructure, recreational activities, and waste management intensifies, which can lead to pollution from wastewater discharge, litter, and increase nutrient runoff. These factors may degrade water quality, threatening marine biodiversity and ecosystem health. Some studies have highlighted this relationship across various geographical regions. A notable impact of TR on the CWQ index was demonstrated in the marine TR Park in Indonesia (Ministry of Land, Infrastructure, Transport and Tourism, 2024). It confirmed that extensive TR expansion in marine protected areas and small islands could lead to declining water quality and heightening environmental vulnerability. A different study highlighted the adverse effects of TR on water quality in Tara National Park in Serbia, with senior and highly educated residents and visitors particularly stressing this issue (World Bank Group, 2024). Vidal-Hernández et al. (2021) provided evidence demonstrating the gradual decline in coastal ecosystems, including fauna, flora, and natural coastal appeal, due to the effects of TR. Drius et al. (2019) indicated that specific studies investigating the primary threats posed by coastal TR and their interactions with other human activities affecting marine ecosystems and water quality remain potential.

Based on previous literature, we develop the below hypothesis.

Hypothesis 4

TR plays an essential role in contributing to CWQ.

FT has the potential to significantly reduce carbon footprints by promoting the adoption of digital financial services and enhancing efficiency in various sectors. FT facilitates more efficient energy usage, streamlined processes, and lower reliance on traditional financial institutions, which are often resource-intensive. Moreover, FT-enabled platforms can foster investment in green technologies, enable carbon tracking, and promote transparency in emissions reporting. This shift not only aids in reducing operational carbon footprints but also encourages environmentally responsible behaviors among consumers and businesses. Studies revealed a substantial positive impact of FT in mitigating carbon footprint across seven resource-rich developing (Leng et al., 2024) and BRICS nations (Kai et al., 2024). Previous studies indicated that policies including additional deductions, scientific financial subsidies, and tax incentives should be implemented to promote FT, thereby advancing core technologies for green innovation and enabling cities to achieve carbon neutrality goals (Teng and Shen, 2023). FT demonstrates substantial strength in addressing environmental issues, exerting a bidirectional impact on the environment. It not only fosters innovative solutions but also contributes to minimizing environmental pollution. For instance, blockchain-based applications enhance supplier transparency and promote healthy consumer habits through virtual transactions. Moreover, FT plays a pivotal role in facilitating green credit operations (Liu et al., 2022). It also enables the development of advanced financial products such as carbon trading and green bonds, providing new avenues for funding climate change mitigation projects (Rahman et al., 2023). Additionally, FT’s emphasis on digitalization reduces the negative environmental impact associated with traditional banking while creating opportunities to maximize economic outcomes (Goel, 2022). This encourages businesses to adopt environmentally conscious practices and transform corporate operations through the use of cryptocurrencies.

Based on relevant literature, we develop the following hypothesis.

Hypothesis 5

FT plays an essential role in contributing to EE.

The relationship between FT and CWQ represents a critical yet underexplored area in existing literature. FT’s potential to influence CWQ lies in its ability to facilitate green financing mechanisms, such as crowdfunding and green bonds, which can be directed toward projects aimed at coastal preservation and pollution mitigation. Blockchain technology, a subset of FT, offers possibilities for improving transparency in supply chain practices, particularly in industries contributing to marine pollution. Chhipi-Shrestha et al. (2023) argued that AI and supply chain applications were essential for autonomous digital water quality management. These methods have primarily been utilized to predict, assess, and regulate water quality more precisely. Dong et al. (2024) initially supposed that FT, encompassing mobile payments, online banking, blockchain technology, cryptocurrency, and crowdfunding platforms, enhances and democratizes financial activities but may have unintended environmental consequences, including impacts on water quality. However, their study does not delve deeply into this relationship. Jiang et al. (2019) examined and concluded that there is an inverted U-shaped relationship between the development of FT and non-point source agricultural pollution, a major contributor to surface water quality degradation. Generally, studies linking these capabilities to measurable improvements in CWQ are scarce. This gap is significant given the urgent need for innovative solutions to address coastal degradation driven by TR, urbanization, and industrial discharges.

Based on previous literature, we develop the below hypothesis.

Hypothesis 6

FT plays an essential role in contributing to CWQ.

In this paper, our model is constructed based on the widely recognized STIRPAT (Stochastic Impacts by Regression on Population, Affluence, and Technology) framework proposed by Dietz and Rosa (1997) and extended including FT by Leng et al. (2024). Additionally, due to the nonlinear exponential relationship between GFP and TR with environmental factors as demonstrated by several studies (Ehigiamusoe, 2020; Aldama and Creel, 2019), we apply natural logarithms and incorporate them into the STIRPAT model. The relationship between FT and ecological degradation is suggested to follow an inverted U-shaped pattern (Murshed, 2024). We then quantify CWQ using the widely recognized single-factor index method proposed by Debels et al. (2005) and then apply natural logarithms. The selection of this method is based on the availability of data accessible to the authors. Additionally, this approach is both widely used and suitable for assessing water quality characteristics, as evidenced by its application in numerous studies conducted in China (Tian et al., 2019; Wu Z et al., 2021; Wang et al., 2019). C W Q = I 1 . I 2 I 3 I 4 (1) where I 1 × I 2 averages the single-factor C W Q tagging variable of all estimated indicators; I 3 denotes the number of single indexes in the full-scale C W Q assessment falling short of the functional zone target for the water environment; I 4 denotes the comparative result between the complete C W Q group and the overall functional zone target for the water environment. C W Q represents the complete level of coastal water pollution.

The single-factor index Q specializes in exceeding the target C W Q degree using a single index that applies weight modification (see Equations 2–4). I 1 . I 2 = ∑ i = 1 n Q i × w i (2) w i = m i ∑ m i (3) m i = I 1 − μ + 1 (4) where n represents the number of single indexes to measure the C W Q ; Q i is the single-factor indicator of the i t h C W Q variable rounded to two decimal digits; w i denotes the weight; μ is the target C W Q benchmark; whereas m i is the exceedance degree of a single C W Q standard.

In this study, to calculate the C W Q index, we utilized the indicators of salinity and density of total nitrogen, total phosphorus, and chlorophyll a (Chl.a), and applied Equation 1 to compute the C W Q index.

To implement the MMQR model for robust test estimation, we undertake the following three-step procedure: Cross-sectional dependence (CSD) test, Panel cointegration test, and panel estimation using MMQR.

It can be observed that the government’s current investment in green projects, while effective in preventing environmental degradation, demonstrates stronger efficiency at lower pollution levels and weaker efficiency at higher pollution levels, particularly concerning the CWQ index. In terms of CWQ, areas with severe pollution levels experience even worse negative impacts. Conversely, the adverse effects on heavily air-polluted regions are less pronounced compared to those with moderate and low pollution levels. This suggests that, for TR, CWQ should be a more prominent policy priority than air pollution. FT, on the other hand, exhibits a more significant impact on severe air pollution, while its effects on heavy marine water pollution remain less evident. Therefore, further development of FT solutions that positively influence CWQ is necessary.

Theoretically, it is evident that government investments in green projects have proven effective in improving air quality and CWQ. However, government investments and fiscal tools aimed at promoting green TR have not yet delivered the expected results. Also, this paper demonstrates the existence of local thresholds at which the expansion of FT reverses its impact on both EE and CWQ. Therefore, the paper lays the groundwork and suggests exploring these thresholds to provide more accurate recommendations for proposing investment and development policies for FT.

Based on research findings, the author provides the following policy recommendations. (1) The government’s portfolio of green project investments should include the TR sector, with a balanced allocation of weights relative to other sectors. Additionally, the implementation of fiscal tools should be regularly monitored and evaluated to prevent overinvestment beyond the point of effectiveness, thereby avoiding waste. (2) The government should gradually increase environmental taxes targeting the TR sector. Currently, environmental taxes in China are in a phase of ‘tax transformation-transition,’ with tax rates remaining below the actual pollution emission levels. (3) Given the inevitable development and expansion of TR and FT, local authorities may hesitate to implement fiscal tools that could hinder this growth. They might consider adopting a combination of innovative measures that incentivize businesses to focus on green TR development, such as carbon credit solutions. Exploring pilot programs that allow cryptocurrency payments for businesses committed to green TR is also worth investigating. The dual benefit of these solutions could provide significant potential for businesses to contribute to environmental quality improvement. (4) For FT, due to its diverse forms of development and the rapid pace at which this diversity continues to grow, it is essential to disaggregate these forms and continuously monitor and examine their actual impacts on EE and CWQ. (5) The impact of FT on environmental indicators shifts depending on pollution levels and water quality, making the identification of local thresholds (the peaks of the inverted U-shape) critically important. If authorities fail to recognize these thresholds, the expansion of FT could harm the environment. Since each type of pollution has distinct thresholds, controlling FT development must account for these variations.