Water Ecosystem Service Quality Evaluation and Value Assessment of Taihu Lake in China

Spatial-temporal variation and correlation analysis of ecosystem service values and ecological risks in winter city Shenyang, China

Ecosystems in winter cities are complex and fragile, experiencing significant changes due to climate variations and human construction activities. Previous studies on the assessment of overall ecosystem service value (ESV) and ecological risk index (ERI) in winter cities are scarce. In this study, we constructed ESV and ERI measurement models using land use data in 2000, 2010, and 2020 using the improved value per unit area factor method and the landscape pattern index method, respectively, to reveal their spatial and temporal change characteristics. Geographic detectors were used to explore the driving roles of natural and artificial factors on the changes of ESV and ERI. The combination in ESV and ERI can then provide a more quantitative and accurate basis for policy decisions, identify priority areas for urban ecological restoration, and reduce the risk to ecosystems. The results of the study show that the total ESV of Shenyang city decreased from 273.97 × 108 CNY to 270.38 × 108 CNY during 2000-2020. Although the decrease is not large, the ESV changes structurally with the advancement of urbanization. During the 20 years, the construction land with the lowest ecological service function continues to expand, increasing by 354 km2, the grassland decreased by 215.9 km2, and the arable land decreased by 196.6 km2. The ecological service function of the water area is the strongest, with an increase of 51.3 km2 in the water area, ensuring that there is no significant decline in ESV. The size of the ERI is Very high, High, and Medium value zones remained relatively stable, while the size of the Very Low-value zone decreased by 12.78% and the size of the Low-value zone increased by 13.21%. The interaction factors that contributed most to the changes in ESV and ERI were annual evapotranspiration (EVP)/ Normalized Difference Vegetation Index (NDVI) and Annual sunshine hours (SSD)/ Digital Elevation Model (DEM) , respectively. There was a spatial correlation between ESV and ERI. The areas with the highest ESV supply capacity and at the same time facing severe ecological risks to the landscape pattern are distributed in the northeastern hilly lands. This area should be prioritized to develop planning and control measures to prevent further erosion of forest lands and grasslands and reduce ecological risks. These results provide a theoretical basis for ensuring ecological security and sustainable development in winter cities.

Applications-oriented algicidal efficacy research and in-depth mechanism of a novel strain Brevibacillus sp. on Microcystis aeruginosa

The utilization of algicidal bacteria for the control of harmful algal blooms (HABs) is a promising technology for ecological remediation. In our most recent publication, a novel strain of Brevibacillus sp. was isolated and proved to have significant algicidal activity and stability against Microcystis aeruginosa. In order to verify the algicidal effect of the strain in the practical application scenario, the algicidal efficacy of Brevibacillus sp. under conditions close to water in the environment was investigated. Results indicated that the algicidal threshold of Brevibacillus sp. culture was 3‰ inoculation concentration, and the removal rate of M. aeruginosa reached 100%. The process of Chl-a degradation followed a first-order kinetic model, which could be used to predict the degradation effect of M. aeruginosa in practical applications. Additionally, the inoculation of Brevibacillus sp. culture introduced additional nutrients, some of which remained in the water. Furthermore, the algicidal substances demonstrated good sustainability, with a removal rate of up to 78.53% at 144 h after three repeated uses. At 12 h, the algicidal substances caused a 78.65% increase in malondialdehyde (MDA) content in M. aeruginosa compared to the control group, thereby triggering the antioxidant system of M. aeruginosa. Moreover, algal cell fragments were observed to aggregate. This study provides a promising direction for treating cyanobacterial blooms using algicidal bacteria in practical applications.

Unsupervised biological integrity assessment by eDNA biomonitoring of multi-trophic aquatic taxa

The biological integrity of global freshwater ecosystems is threatened by ever-increasing environmental stressors due to increased human activities, such as land-use change, eutrophication, toxic pollutants, overfishing, and exploitation. Traditional ecological assessments of lake or riverine ecosystems often require human supervision of a pre-selected reference area, using the current state of the reference area as the expected state. However, selecting an appropriate reference area has become increasingly difficult with the expansion of human activities. Here, an unsupervised biological integrity assessment framework based on environmental DNA metabarcoding without a prior reference area is proposed. Taxon richness, species dominance, co-occurrence network density, and phylogenetic distance were used to assess the aquatic communities in the Taihu Lake basin. Multi-gene metabarcoding revealed comprehensive biodiversity at multiple trophic levels including algae, protists, zooplankton, and fish. Fish sequences were mainly derived from 12S, zooplankton mainly from mitochondrial cytochrome C oxidase subunit I, and algae and protists mainly from 18S. There were significant differences in community composition among lakes, rivers, and reservoirs but no significant differences in the four fundamental biological indicators. The algal and zooplankton integrities were positively correlated with protist and fish integrities, respectively. Additionally, the algal integrity of lakes was found to be significantly lower than that of rivers. The unsupervised assessment framework proposed in this study allows different ecosystems, including the same ecosystem in different seasons, to adopt the same indicators and assessment methods, which is more convenient for environmental management and decision-making.

Comprehensive evaluation of water ecological environment in watersheds: a case study of the Yangtze River Economic Belt, China

The Yangtze River Economic Belt, an inland economic zone with global influence, has shown a trend of prosperous economic development in recent years. Economic development, water pollution, resource depletion, and other environmental problems continue to emerge. The steady state of the water ecological environment is an important aspect of ecological security. To investigate the regional water ecological security state, this study constructs a comprehensive evaluation indicator system within the framework of "driving force-carrying source-state-management" (DCSM). The entropy weight method was used to determine the weight of each indicator, and the weighted rank sum ratio model was introduced to classify the water ecological environment of the Yangtze River Economic Belt from 2010 to 2019. Finally, an adversarial interpretative structure model is used to refine the ranking of each region. The results show that the bearing state and driving force subsystems are closely related to the water ecological environment. The top three indicators are wastewater discharge of industrial added value of 10,000 yuan, water consumption per 10,000 yuan of industrial gross product, and water consumption per 10,000 yuan of tertiary gross domestic product. In addition, there are clear differences in the water ecological environment of the Yangtze River Economic Belt. The classification results show that Zhejiang and Jiangsu are rated as "excellent''; Yunnan, Guizhou, Anhui, and Jiangxi are in the "good" level; and Sichuan, Hunan, Chongqing, and Hubei are in the "medium" level. Shanghai is "poor." As a whole, the downstream is superior, the upstream is second, and the midstream is poor in an asymmetric "U"-shaped distribution. During the study period, the overall state of water ecology in the Yangtze River Economic Belt was at a medium level and has not yet reached a safe and steady state. The performance of areas with traditional industrialization as the main development path was poor. Therefore, it is necessary to pay attention to the overall water ecological security in the basin in the future, strengthen the regulatory role of the government's water ecological management, promote reform of traditional industries and resource-based regions, and achieve the sustainable development of the water ecological environment.

Design and Application of an Early Warning and Emergency Response System in the Transboundary Area of the Taihu Lake Basin

The inter-provincial transboundary area of the Taihu Lake Basin is characterized by a complex river network and reciprocating flow. Frequent environmental pollution events in recent years have become a major safety hazard for the water quality in the Taihu Lake Basin. There are few early warning systems for environmental pollution events in China, the ability to simulate risk is insufficient, and systematic research on technology, development, and application is lacking. Thus, water management requirements are not met in the inter-provincial transboundary area of the Taihu Lake Basin. This paper proposes a cross-border risk management plan for pollution sources in the transboundary areas of the Taihu Lake Basin and an early warning and emergency response system for water pollution events using modern information technology. We used this system to assess and classify 2713 risk sources for nitrogen and phosphorus pollution into 5 categories. We simulated the discharge of a pollutant into a tributary and the early warning and emergency response for the transboundary region. The results indicate that the proposed early warning and emergency response system substantially improved the transboundary water environment and lowered the risk of pollution in the Taihu Lake watershed.

Research on the Coordinated Governance Mechanism of Cross-Regional and Cross-Basin Ecological Compensation in the Yangtze River Delta

The development of a regionally integrated economy promotes the development of river basin ecological compensation toward cross-regional coordinated governance. The ecological compensation in the Yangtze River Delta has developed by leaps and bounds, which is conducive to the research on the collaborative governance mechanism. Taking the ecological compensation policy data in the Yangtze River Delta as the research object, and using the social network analysis method, this paper analyzes the current situation of cross-basin cooperation in the Yangtze River Delta. A collaborative governance network is formed with 74 ecological compensation agreements, and the distribution law of the overall collaborative network is found. Using IAD to decompose the ecological compensation agreement rules, 303 institutional units were obtained, of which, 198 were selection rules, accounting for 65%. The research results show that: (1) The ecological compensation cooperation in the Yangtze River Delta region is mainly concentrated in the Jiaxing Jiashan, Wujiang District, Suzhou, and Qingpu District, Shanghai, forming a close cooperation triangle network, and Shanghai plays a strong "intermediary" role in it. (2) In institutional grammar analysis, the formulation of rules is biased toward choice rules and payoff rules, that is to say, the content of the rules is mostly how to cooperate and how to reward and punish but there is a lack of specific action scenarios and standards. The combination of social network and institutional analysis and development framework is conducive to the study of the ecological collaborative governance mechanism of the Yangtze River Delta, breaking the gap between different fields and regions, enhancing the enthusiasm for multi-subject governance in the Yangtze River Delta region, and giving full play to the effectiveness of multi-subject governance.

Spatial–Temporal Variations of Water Ecosystem Services Value and Its Influencing Factors: A Case in Typical Regions of the Central Loess Plateau

Water resources provide indispensable ecosystem services, which are related to human well-being and sustainable social development. Accurately measuring the water ecosystem services value (WESV), and then grasping its changing characteristics, is particularly important for solving water problems. In this study, the typical area of the central Loess Plateau location is taken as the research area. Based on remote sensing images and statistical data, the direct market method combined with the equivalent factor method was used to calculate the WESV including groundwater and surface water, which is of greatest originality. The temporal and spatial variation characteristics in 2010, 2015 and 2020 were analyzed. Then, four WESV driving factors including per capita GDP, population density, proportion of water areas, and water consumption were selected, and the geographically weighted regression (GWR) model was used to analyze the spatial distribution pattern and temporal variation of WESV’s response to the influencing factors. The results showed that WESV experienced a process of first decreasing and then increasing, which was mainly caused by Yulin. For the composition of WESV, the proportion of provisioning services value has increased, which caused the proportion of regulating services value to decrease. The correlations between four factors and WESV were different. The distribution pattern of the influences was spatially heterogeneous, which showed regular variations over time. These results indicate the necessity of WESV’s independent research and provide a realistic basis for ecological compensation in the Yellow River Basin.

Water Value Integrated Approach: A Systematic Literature Review

Extreme water incidents point out a value conflict surrounding the resource. While drought and floods echo the inadequate land and resource uses, the increase in social inequalities exposes the practical, physiological, and social consequences. The multiple value action throughout the water cycle also narrowed disputes to those that neglect its vital importance, and the constraints imposed to the services, such as low tariffs, and lack of local engagement, make sustainable water systems more difficult. This article develops a systematic literature review to understand the academic motivations surrounding water value and gaps in its systematic approach. A sample with 84 papers is created by an interactive keyword selection and its general characteristics are presented. A dynamic reading technique extracts data and classifies the papers according to 14 research motivations, where the water multifunctionality and the user value stand out. The bibliographic coupling analysis identifies a cluster of 16 papers related to integration and connected to planning, decision, and management. There is a lack of contribution with a systemic approach to water resources by way of integrating actors and values, such as including local contexts.

Assessing Ecological Infrastructure Investments-A Case Study of Water Rights Trading in Lu'an City, Anhui Province, China

Investment in ecological infrastructure construction alters behaviors and quantities of the ecosystem service (ES) provided, and market-clearing can learn the value and scale of ES. We integrated ecological and economic methods to put forward the idea of realizing the aquatic ecological products’ value by investing in water-saving irrigation infrastructure. Firstly, the demand for aquatic ecological products was calculated by a Cobb–Douglas production function, and then the supply of aquatic ecological products was estimated by InVEST and water-saving potential models; Finally, the scale of ecological infrastructure investment and the aquatic ecological products’ value are illustrated by cost-benefit analysis and market equilibrium theory. Research indicates that, (1) industrial water efficiency is high, and the ecological infrastructure construction provides a considerable number of ecological products; (2) implementing water-saving irrigation project is at least 30% more profitable than maintaining the status quo; (3) the market-clearing results showed that the market equilibrium price is about 0.256 USD/m³, and the transaction volume is about 1.667 billion m³. The output value of industrial enterprises after buying water can reach about 1.37 times of the current stage, reflecting the aquatic ecological products’ value. Investment in water-saving irrigation infrastructure has huge economic, social and ecological benefits, and provides reference for decision-making.

Two-Step Measurement of Water-Energy-Food Symbiotic Coordination and Identification of Key Influencing Factors in the Yangtze River Basin

With the intensification of people's production and life behaviors, the systemic risks of water, energy and food in the Yangtze River Basin have become increasingly prominent, which has become a bottleneck for sustainable development of social, economic and ecological in the basin. Therefore, studying the symbiotic coordination between water, energy and food is of great significance to promoting regional sustainable development. First, from the perspective of water-energy-food symbiosis, with the water-energy-food ecosystem conceptual model as the nexus, the two-step measurement model of the symbiotic index and the symbiotic level index is used to study the water-energy-food symbiosis of the Yangtze River. Then, we use the BP-DEMATEL-GTCW model to identify the key influencing factors that affect the symbiotic security of the water-energy-food ecosystem. In this research, it is found that the average value of the symbiotic degree of the water-energy-food ecosystem of the 11 provinces or municipalities in the Yangtze River Basin only reached the risk grade. It can also be seen from the identification results of key influencing factors that energy microsystem-related indicators have a greater impact on the symbiotic development of the entire WEF ecosystem. Therefore, special attention needs to be paid to increasing energy sources and reducing expenditure. Relevant departments need to effectively develop primary energy production and expand energy-saving investment through multiple channels to expand energy self-sufficiency and ultimately promote the coordinated and effective development of water, energy and food in the Yangtze River Basin.