Search Results (279)

With climate change, the spatial and temporal patterns of precipitation are altered to a certain degree, which potentially affects the grey water footprint (GWF) of total nitrogen (TN) in agriculture, thereby threatening water security in the Yangtze River Basin (YRB), the largest river in China. The current study constructs an assessment framework for climate change impacts on the GWF of agricultural TN by coupling Shared Socioeconomic Pathways (SSPs) with the InVEST model. The framework consists of four components: (i) data collection and processing, (ii) simulating the two critical indicators (L_TN and W) in the GWF model based on the InVEST model, (iii) calculating the GWF and GWF index (GI) of TN, and (iv) calculating climate change impact index on GWF of agricultural TN (CI) under two SSPs. It is applied to the YRB, and the results show the following: (i) GWFs are 959.7 and 961.4 billion m³ under the SSP1-2.6 and SSP5-8.5 climate scenarios in 2030, respectively, which are both lower than that in 2020 (1067.1 billion m³). (ii) The GI values for TN in 2030 under SSP1-2.6 and SSP5-8.5 remain at “High” grade, with the values of 0.95 and 1.03, respectively. Regionally, the water pollution level of Taihu Lake is the highest, while that of Wujiang River is the lowest. (iii) The CI values of the YRB in 2030 under SSP1-2.6 and SSP5-8.5 scenarios are 0.507 and 0.527, respectively. And the CI values of the five regions in the YRB are greater than 0, indicating that the negative effects of climate change on GWFs increase. (iv) Compared with 2020, L_TN and W in YRB in 2030 under the two SSPs decrease, while the GI of TN in YRB rises from SSP1-2.6 to SSP5-8.5. The assessment framework can provide strategic recommendations for sustainable water resource management in the YRB and other regions globally under climate change. Full article

Microbial communities are crucial to maintaining the ecological health of lakes, but their response to water quality and eutrophication is poorly understood. This study analyzed seasonal variation in the effect of water quality parameters on microbial community structure and function at southern Lake Taihu. We observed poor water quality in autumn (low dissolved oxygen concentration and water transparency) with severe eutrophication (high in nitrogen, phosphorus, and microcystins). Microcystins were a major indicator of water quality that affected total phosphorus and dissolved oxygen concentrations. Redundancy analysis revealed that total nitrogen, total phosphorus, nitrate, ammonium, and microcystins, temperature, and dissolved oxygen all significantly influenced the microbial community. Microbial co-occurrence networks revealed significant seasonal variations, with autumn and winter exhibiting a more complex structure than other seasons. Additionally, we identified microcystin-sensitive microbial species as eutrophication indicators; they are involved in bacterial community components and metabolic function and fluctuate under seasonal changes to water quality. In conclusion, our findings provide insight into the relationship between water quality and microbial communities, offering an empirical basis for improving the sustainable management of Lake Taihu. Full article

In this paper, cultivable actinobacteria were isolated, cultured, and identified from the heavily algal-bloomed waters of Taihu Lake using 16S rRNA gene sequencing. Among the isolates, a single strain exhibiting vigorous cyanocidal activity against Microcystis aeruginosa FACHB-905 was selected for further investigation. The cyanocidal efficacy and underlying mechanisms of this strain, designated TH05, were assessed through using chlorophyll content, cyanobacterial inhibition rate, and cyanobacterial cell morphology measurements. In addition, oxidative stress responses, expression of key functional genes in FACHB-905, and variations in microcystin concentrations were comprehensively evaluated. Cyanobacterial blooms caused by Microcystis aeruginosa pose serious ecological and public health threats due to the release of microcystins (MCs). In this study, we evaluated the cyanocidal activity and mechanism of a novel actinomycete strain, Streptomyces sp. TH05. Optimization experiments revealed that a light–dark cycle of 12 h/12 h, temperature of 25 °C, and pH 7 significantly enhanced cyanocidal efficacy. Under these conditions, TH05 achieved an 84.31% inhibition rate after seven days of co-cultivation with M. aeruginosa. Scanning electron microscopy revealed two distinct cyanocidal modes: direct physical attachment of TH05 mycelia to cyanobacterial cells, causing cell wall disruption, and indirect membrane damage via extracellular bioactive compounds. Biochemical analyses showed increased levels of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) during the first five days, peaking at 2.47-, 2.12-, and 1.91-fold higher than control levels, respectively, indicating elevated oxidative stress. Gene expression analysis using elf-p as a reference showed that TH05 modulated key genes associated with photosynthesis (PsaB, PstD1, PstD2, RbcL), DNA repair and stress response (RecA, FtsH), and microcystin biosynthesis (McyA, McyD). All genes were upregulated except for RbcL, which was downregulated. In parallel, microcystin content peaked at 32.25 ng/L on day 1 and decreased to 16.16 ng/L by day 9, which was significantly lower than that of the control group on day 9 (29.03 ng/L). These findings suggest that strain TH05 exhibits potent and multifaceted cyanocidal activity, underscoring its potential for application in the biological control of cyanobacterial blooms. Full article

Recreational fisheries increasingly intersect with the habitats of flagship species, i.e., species that attract public attention and drive conservation efforts, raising potential ecological conflicts. This study investigated the spatial coupling between recreational fisheries and three flagship species in the Yangtze River Basin: the Chinese alligator (Alligator sinensis), the Yangtze finless porpoise (Neophocaena phocaenoides), and the scaly-sided merganser (Mergus squamatus). Drawing on over 10,000 fishing Points of Interest recorded between 2015 and 2024 and over 300 verified species occurrences, this study applied a Random Forest model with spatial integration and a Maximum Entropy model to examine estimated current distributions and forecast interactions from 2025 to 2035. Flagship species habitat suitability was modeled and projected at a spatial resolution of 1 km, while recreational fishing density was resolved on a coarser grid of 1.875° × 1.25° in latitude–longitude dimensions. Results reveal a substantial increase in high-risk overlap zones. For example, high-density fishing areas within high-suitability habitats for the scaly-sided merganser expanded from 0 km² in 2015 to 85,359 km² in 2024. Projections indicate continued intensification of such overlaps, particularly in regions including Ma’anshan–Wuhu, the Taihu–Chaohu–Poyang lake system, and Yibin. These findings offer robust, model-driven evidence of growing spatial conflicts and offer actionable insights for ecosystem-based governance. The methodological framework is transferable and supports broader applications in other regions and species under ecological sustainability goals. Full article

To explore the effects of different plant combinations in ecological floating beds on water quality purification and phytoplankton community structure in shallow eutrophic lakes, we conducted a survey of phytoplankton communities within ecological floating beds featuring distinct plant combinations in Meiliang Bay, Lake Taihu, during June and August 2021. The study focuses on two combinations: EA (Canna indica + Acorus calamus + Phragmites australis) and ES (Canna indica + Oenanthe javanica + Sagittaria sagittifolia). Results indicated that ecological floating beds significantly improved water quality, with the strongest restoration effects observed in the EA area. Specifically, turbidity was reduced by 47–89%, while chlorophyll a (Chl-a) concentration inhibition rates reached 82% in June and 54% in August. The comprehensive trophic state index (TLI) remained stable at levels indicating slight eutrophication (≤58.6). Phytoplankton community structure shifted from dominance by eutrophic functional groups (primarily FG M) toward greater diversity. In the EA area, the number of dominant functional groups increased from five (control) to six, and the abundance of the key cyanobacteria group (FG M) declined from 18.29% (control) to 7.86%. Redundancy analysis (RDA) revealed temporal changes in driving factors: nutrients were primary in June (explanation rate: 64.7%), while physical factors dominated in August (explanation rate: 51.2%). This study demonstrates that installing ecological floating beds with diverse plant combinations in shallow eutrophic lakes can effectively alter phytoplankton community structure and enhance in situ water restoration. Among the tested combinations, EA (Canna indica + Acorus calamus + Phragmites australis) exhibited the optimal restoration effect. These findings provide a scientific basis for water environment protection and aquatic biological resource restoration in shallow eutrophic lakes. Full article

This study investigates the spatiotemporal distribution and evolution of traditional villages in southern Jiangsu Province, China. By integrating historical documents, remote sensing images, and socio-economic statistics, we have applied standard geographic information system (GIS) methods, including kernel density estimation, nearest neighbor analysis, and standard deviation ellipse analysis, to examine the patterns and driving forces behind village formation and transformation. The findings are as follows: (1) The spatial distribution of the villages exhibits a spatial pattern of “peripheral agglomeration and central decline,” with a nearest neighbor index value of 0.84 (z = −2.52, p < 0.05), indicating a significantly clustered distribution. Kernel density analysis revealed high-density zones along the southwestern coast of Taihu Lake and southeastern Dianshan Lake. (2) From the Song to the Qing Dynasty, village migration followed three sequential phases, “stabilizing near water → avoiding risks around water → adapting inland,” showing strong spatiotemporal linkages to climate change and warfare. (3) The density of the villages showed a significant negative correlation with the per capita GDP (Moran’s I = −0.69, p < 0.05; 0.69, p < 0.01) and was positively correlated with the proportion of primary industry. These findings highlight the spatial resilience characteristics of traditional villages under combined natural and socio-economic pressures and provide a theoretical foundation for regional heritage conservation and rural revitalization strategies. Full article

Lakes are important sinks for antibiotics as suspended particulate matters (SPMs) in lakes have become significant carriers of antibiotic adsorption and migration. The light and heavy fractions of SPM are involved in the process of suspension and sedimentation in the aqueous environment. Combined with the adsorption behaviors of antibiotics onto SPM, a basis for the risk of antibiotic migration in lakes will be provided. In this study, SPM from Lake Taihu was collected and grouped according to density as light fraction (LF) and heavy fraction (HF), with heavy fraction including loosely bound humus (WLH) and tightly bound humus (TH). Adsorption studies were carried out with three typical antibiotics: tetracycline hydrochloride (TC), norfloxacin (NOR), and trimethoprim (TMP). The adsorption processes of all particulate fractions towards antibiotics were fast, which is consistent with pseudo-second-order kinetics. The adsorption in the TC and NOR groups was much higher than that in the TMP group, which was mainly related to the properties of the antibiotics. The LF group was the special component with the fastest adsorption rate, the largest adsorption amount, and the lowest desorption ratio, regardless of antibiotics, which is related to the organic matter content and the rich-carbon-containing functional groups in the LF group, such as -C=O. These findings highlight the need for further attention to the high adsorptive transport effect of LF on antibiotics in lake ecosystems. Full article

Urban flooding poses escalating threats to socioeconomic stability and human safety, exacerbated by urbanization and climate change. While urban flood resilience (UFR) has emerged as a critical framework for flood risk management, existing studies often overlook the systemic integration of post-disaster recovery capacity and multidimensional interactions in UFR assessment. This study develops a novel hazard–vulnerability–exposure–defense capacity–recovery capacity (HVEDR) framework to address research gaps. We employ a hybrid game theory combined weight method (GTCWM)-TOPSIS approach to evaluate UFR in China’s Taihu Lake Basin (TLB), a region highly vulnerable to monsoon- and typhoon-driven floods. Spanning 1999–2020, the analysis reveals three key insights: (1) weight allocation via GTCWM identifies defense capacity (0.224) and hazard (0.224) as dominant dimensions, with drainage pipeline density (0.091), flood-season precipitation (0.087), and medical capacity (0.085) ranking as the top three weighted indicators; (2) temporal trends show an overall upward trajectory in UFR, interrupted by a sharp decline in 2011 due to extreme hazard events, with Shanghai and Hangzhou exhibiting the highest UFR levels, contrasting Zhenjiang’s persistently low UFR; (3) spatial patterns reveal stronger UFR in southern and eastern areas and weaker resilience in northern and western regions. The proposed HVEDR framework and findings provide valuable insights for UFR assessments in other flood-prone basins and regions globally. Full article

As a crucial component of the Beijing–Hangzhou Grand Canal’s hydraulic engineering, the Jiangnan Canal has historically played a pivotal role in China’s development as a key hydraulic infrastructure. This water conservancy project, connecting northern and southern water systems, not only facilitated regional economic integration but also nurtured unique cultural landscapes along its course. The Jiangnan Canal and its adjacent cities were selected as the study area to systematically investigate 334 tangible cultural heritage (TCH) sites and 420 intangible cultural heritage (ICH) elements. Through integrated Geographical Information System (GIS) spatial analyses—encompassing nearest neighbor index, kernel density estimation, standard deviation ellipse assessment, multi-ring buffer zoning, and Geodetector modeling, the spatiotemporal distribution features of cultural heritage were quantitatively characterized, with a focus on identifying the underlying driving factors shaping its spatial configuration. The analysis yields four main findings: (1) both TCH and ICH exhibit significant spatial clustering patterns across historical periods, with TCH distribution displaying an axis-core structure centered on the canal, whereas ICH evolved from dispersed to clustered configurations. (2) The center of gravity of TCH is primarily around Taihu Lake, while that of ICH is mainly on the south side of Taihu Lake, and the direction of distribution of both is consistent with the direction of the canal. (3) Multi-ring buffer analysis indicates that 77.2% of TCH and 49.8% of ICH clusters are concentrated within 0–10 km of the canal, demonstrating distinct spatial patterns: TCH exhibits a gradual canal-dependent density decrease with distance, whereas ICH reveals multifactorial spatial dynamics. (4) Human activity factors, particularly nighttime light intensity, are identified as predominant drivers of heritage distribution patterns, with natural environmental factors exerting comparatively weaker influence. These findings provide empirical support for developing differentiated conservation strategies for canal-related cultural heritage. The methodology offers replicable frameworks for analyzing heritage corridors in complex historical landscapes, contributing to both applied conservation practices and theoretical advancements in cultural geography. Full article

To study the structure and distribution characteristics of the phytoplankton community in the Huaihe River Basin, Yangtze River Basin, and Taihu Lake Basin in Jiangsu Province, 126 sampling sites were set up in 35 rivers in the region, and samples were collected during the wet season (August–September) in 2023. Based on the monitoring results of phytoplankton, the study selected 20 candidate indicators and conducted range screening, discriminative ability analysis, and correlation analysis. Finally, seven core indicators were determined to construct the Phytoplankton Biological Integrity Index (P-IBI) evaluation system. The rating standards were determined by the ratio method, and the phytoplankton integrity of Jiangsu Province was evaluated. The differences were analyzed. As the results showed, the overall health status of rivers in Jiangsu Province was general. From the point of view of the basin scope, the Huaihe River Basin and the Yangtze River Basin were in sub-healthy state, and the Taihu Lake Basin was general. There were significant differences in the phytoplankton density community structure in the Yangtze River, Huaihe River, and Taihu Lake Basins. Phytoplankton integrity was positively correlated with total nitrogen and nitrate nitrogen, but not with other environmental factors. Nitrogen is the main factor affecting the integrity of river phytoplankton in Jiangsu Province. Full article

Lake Taihu, China’s third-largest freshwater lake, faces severe eutrophication challenges and therefore requires innovative ecological restoration strategies. This study systematically evaluates the ecological effects of aquatic vegetation restoration in Baimao Bay through comprehensive analysis of macrobenthic communities and environmental parameters, demonstrating significant water quality improvements including a 42.9% decrease in total phosphorus, a 69.4% decline in chl-a concentration, a 34.8% reduction in ammonium nitrogen, and a 81.2% increase in water transparency. Multivariate analysis revealed a fundamental ecological driver shift where post-restoration pH and transparency replaced nutrients as dominant factors, reducing total nitrogen/total phosphorus influence by 40–60%, while filter-feeding species (predominantly bivalves and gastropods) became the dominant macrobenthic biomass group (72.4%) with pollution-tolerant oligochaetes decreasing by 69.1% in abundance, alongside distinct spatial heterogeneity showing pH-regulated lakeshore communities (8.37 to 8.45), transparency-governed shallow-water communities (H′ = 1.35), and a residual nutrient-influenced deep-water area, with a shallow-water area (<2.5 m) unexpectedly exhibiting 3.2 times higher biomass (222.51 g/m²) than deep waters, highlighting vegetation-mediated habitat optimization. These findings advance restoration ecology theory by elucidating ecosystem transition mechanisms from nutrient-driven to light-regulated systems while providing a replicable technical framework for global shallow eutrophic lake restoration, establishing quantitative benchmarks including target transparency (>64 cm) and chlorophyll-a levels (<10 μg/L) for effective eutrophication reversal. Full article

Riverine and lacustrine shorelines are crucial for human survival and development, but their natural and ecological environments are highly fragile and sensitive. Intensified human activities have placed unprecedented pressure on the shoreline ecosystem of the Yangtze River Basin. This study investigates the degradation of river and lake shorelines and its cascading effects on ecological service functions. Using Sentinel-2 as the primary data source, we analyzed land use/cover changes and ecosystem service values (ESV) in the Huanggang and Taihu sections of the Yangtze River from 2018 to 2022. The supervised classification results using the support vector machine (SVM) algorithm exceeded 95% accuracy. In the Huanggang section, vegetation was significantly converted into cultivated land and built-up areas (−6.17 km²), while in the Taihu section, water bodies were largely transformed into agricultural land (−3.77 km²). In this study, we quantified changes in ESV using the unit area equivalent factor method, adjusted based on net primary productivity, precipitation, and the soil conservation coefficient. The results indicate that the ESV ranking in both sections follows the order: water conservation > environmental purification > biodiversity > soil conservation. From 2018 to 2022, the ESV in the Huanggang section declined due to forest and grassland loss and an increase in bare land. In contrast, ecological restoration and habitat protection policies contributed to an improvement in ecosystem service functions in the Taihu section, with various ESV components increasing as follows: soil conservation (8.79%) > biodiversity (6.67%) > environmental purification (5.98%) > water conservation (5.52%). These findings provide valuable insights for decision-making in the protection and management of the Yangtze River Basin ecosystem. Full article

In recent years, with the rapid socioeconomic development of Wuxi City, the frequent occurrence of severe air pollution events has attracted widespread attention from both the local government and the public. Based on the real-time monitoring data of criteria pollutants and GDAS (Global Data Assimilation System) reanalysis data, the spatiotemporal variation patterns, meteorological influences, and potential sources of major air pollutants in Wuxi across different seasons during 2019 (pre-COVID-19) and 2023 (post-COVID-19 restrictions) are investigated using the Pearson correlation coefficient, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) models. The results demonstrate that the annual mean PM_2.5 concentration in Wuxi decreased significantly from 39.6 μg/m³ in 2019 to 29.3 μg/m³ in 2023, whereas the annual mean 8h O₃ concentration remained persistently elevated, with comparable levels of 104.6 μg/m³ and 105.0 μg/m³ in 2019 and 2023, respectively. The O₃ and particulate matter (PM) remain the most prominent air pollutants in Wuxi’s ambient air quality. The hourly mass concentrations of criteria pollutants, except O₃, exhibited characteristic bimodal distributions, with peak concentrations occurring post-rush hour during morning and evening commute periods. In contrast, O₃ displayed a distinct unimodal diurnal pattern, peaking between 15:00 and 16:00 local time. The spatial distribution patterns revealed significantly elevated concentrations of all monitored species, excluding O₃, in the central urban zone, compared to the northern Taihu Lake region. The statistical analysis revealed significant correlations among PM concentrations and other air pollutants. Additionally, meteorological parameters exerted substantial influences on pollutant concentrations. The PSCF and CWT analyses revealed distinct seasonal variations in the potential source regions of atmospheric pollutants in Wuxi. In spring, the Suzhou–Wuxi–Changzhou metropolitan cluster and northern Zhejiang Province were identified as significant contributors to PM_2.5 and O₃ pollution in Wuxi. The potential source regions of O₃ are predominantly distributed across the Taihu Lake-rim cities during summer, while the eastern urban agglomeration adjacent to Wuxi serves as major potential source areas for O₃ in autumn. In winter, the prevailing northerly winds facilitate southward PM_2.5 transport from central-northern Jiangsu, characterized by high emissions (e.g., industrial activities), identifying this region as a key potential source contribution area for Wuxi’s aerosol pollution. The current air pollution status in Wuxi City underscores the imperative for implementing more stringent and efficacious intervention strategies to ameliorate air quality. Full article

Sediment is a core part of lake ecosystems, and its organic matter (OM) content is a key indicator of lake ecological health and regional carbon cycling. OM provides nutrients for phytoplankton and algae in water, thereby influencing the degree of lake eutrophication. However, excessively high OM content may trigger water eutrophication, alter sediment’s physical and chemical properties, and ultimately threaten the stability and health of ecosystems. This study innovatively selected Poyang Lake, Taihu Lake, Qinghai Lake, and Hulun Lake from China’s four major geographical regions to systematically investigate sediments’ OM content, sources, and distribution characteristics at different times. The results showed that the organic matter content of sediments in lakes from different regions varied significantly and was influenced by multiple factors, such as watershed characteristics, eutrophication levels, human activities, and climate change. Poyang Lake and Taihu Lake, characterized by high levels of agricultural activities and urbanization within their basins, exhibit significant fluctuations in organic matter content, with total organic carbon (TOC) levels ranging from 0.35% to 2.9% and 0.7% to 2.4%, respectively. In contrast, Qinghai Lake and Hulun Lake, influenced by natural conditions and ecological policies, show relatively stable TOC levels, ranging from 1.3% to 2.75% and 1.25% to 3.58%, respectively. By analyzing sediments’ OM content and combining methods such as organic carbon, nitrogen isotopes, and organic C/N ratios, it is possible to effectively assess the ecological health of lakes, provide critical data support for pollution control, and play a significant role in carbon cycle management. Full article

Cyanobacteria harmful blooms (Cyano-HABs) have become a globally critical environmental issue, threatening freshwater ecosystems by degrading water quality and posing risks to human and aquatic life. Chlorophyll-a (Chl-a), a key biomarker of bloom intensity, offers crucial insights into algal bloom dynamics. However, predicting Chl-a concentrations remains challenging due to the complex interactions between various environmental factors. This study utilizes machine learning (ML) models to predict Chl-a concentrations, focusing on Lake Taihu in China, a large eutrophic lake that serves as an example of numerous freshwater lakes suffering from Cyano-HABs. The research leverages nine critical water quality parameters—water temperature, pH, dissolved oxygen, turbidity, electrical conductivity permanganate index, ammonia nitrogen, total phosphorus, and total nitrogen—to develop an ensemble ML model using XGBoost, known for its ability to handle nonlinear relationships and integrate multiple variables. The XGBoost model achieved superior predictive accuracy with an R² value of 0.78 and RMSE of 8.97 mg/m³ on the test set, outperforming traditional models like linear regression, decision trees, multi-layer perceptrons, support vector regression, and random forests. Feature importance analysis identified electrical conductivity, turbidity, and water temperature as the most significant predictors of Chl-a levels. This study further enhances model interpretability through Pearson correlation analysis, which quantifies the relationships between Chl-a concentrations and other water quality factors. Additionally, we employed principal component analysis (PCA), mutual information, Spearman rank correlation coefficients, and SHAP models to analyze feature importance and model interpretability in ML. The model’s robustness was tested across multiple monitoring sites in Lake Taihu, demonstrating its potential for broader application in other eutrophic lakes facing similar environmental challenges. By providing a reliable tool for forecasting Chl-a concentrations, this research contributes to the development of early warning systems that can help mitigate the impacts of Cyano-HABs, aiding in more effective water resource management. Full article