Nansihu Lake Research Articles

Integrating ecosystem services trade-off, drivers and zoning into watershed water environment management in Nansihu Lake Basin, China

A series of ecosystem services (ESs) have a significant impact on water environment. How these ESs can be integrated into water environment management in the lens of coupled human and natural system (CHANS) is still lack exploration. This study proposes an integrating framework that connects the ESs with water environment management to facilitate the watershed sustainable development. We employ the InVEST model to evaluate typical ESs in the Nansihu Lake Basin (largest freshwater lake in Shandong, China), and analyze the spatiotemporal characteristics and trade-off of multiple ESs indicators. By revealing the interaction mechanism and key drivers of ESs and conducting ecological functional zoning, we investigate how ESs can facilitate water environment management in the Nansihu Lake Basin. The results indicated that: (1) The high-value areas of agricultural supply service are mainly distributed in the western plain area of the basin, while high-value areas of water provision, water purification and soil conservation services are in the mountainous and hilly areas in the eastern part of the basin. (2) There is a significant trade-off between crop supply service and water purification services. Crop and livestock supply services have a greater effect on water purification services (TN) than other services. (3) Crop area sown, total power of agricultural machinery and fertilizer application are the main drivers of water purification services (TN). (4) The basin can be divided into three ecological function zones, the agricultural production zone, the ecological regulation zone and the ecological redline zone. These findings imply that water environment management should be integrated with ESs by strengthening intersectoral collaboration, conducting zoning management in watershed planning and applying differentiated control measures in each zone. This includes optimizing the scale and structure of agriculture, and implementing circular economy and clean production practices. This study explored a comprehensive framework of integrating ESs into water environment management to facilitate the sustainable development of watershed.

多情景模拟下南四湖流域生态系统服务权衡变化研究

多情景模拟下南四湖流域生态系统服务权衡变化研究

Spatial Variability Characteristics and Influencing Factors of Soil Fluoride in the Western Nansihu Lake Basin

The western plain of the Nansihu Lake Basin (NLB) is an important agricultural economic zone in Shandong Province, where there is a high content of fluoride in soils. Studying the content and influencing factors of fluoride in soils is of great significance for the maintenance of regional eco-logical security and human health. This study takes the farmland soils in the west of NLB as the research focus and uses a method based on GIS and geostatistics to quantitatively analyze the spatial variation characteristics of soil total fluoride and water-soluble fluoride contents to draw a map showing their spatial distribution. The effects on the spatial distribution of soil total fluoride and water-soluble fluoride were analyzed from the aspects of geomorphological type, soil parent material (stratigraphic lithology), crop type, and groundwater fluoride concentration, among others, and the correlation between groundwater and soil fluoride contents was also analyzed. Our study results in the following findings: (1) The average content of total fluoride in topsoil in the study area is 652.8 mg/kg, the national background value is exceeded in 99.5% of the sampling sites, and the background value of Shandong Province is exceeded in 98.7% of the sampling sites. The average water-soluble fluoride is 15.2 mg/kg and exceeds 5.0 mg/kg in 94.3% of the sampling sites. Topsoils have high values of total fluoride and water-soluble fluoride. (2) The total fluoride and water-soluble fluoride in topsoils exhibit moderate spatial variability, indicating that their spatial distribution is the result of structural factors such as soil parent materials and man-made random factors such as fluorinated fertilizers. (3) In the 2 m vertical profile of shallow soils, total fluoride and water-soluble fluoride increase with the increase in soil viscosity, and the water-soluble fluoride has the characteristics of surface aggregation due to the influence of soil adsorption. Because fluoride ions as ligands are easily adsorbed and form fluoride complexes with other ions such as aluminum ions, the water-soluble fluoride shows the characteristics of surface aggregation and fractionation. (4) The analysis of influencing factors reveals that the lithology of Quaternary strata, geomorpho-logical types, and planting crop types have significant effects on the distribution of the total fluoride and water-soluble fluoride in the topsoils, and the distribution of the groundwater soluble fluoride in the topsoils is not related to that in groundwater. Our study provides data and technical support for improving both the soil environmental quality and water quality of the eastern route of the South-to-North Water Transfer Project, thus helping to promote the sustainable development of the social economy and ecological environment in the NLB.

Dependence of the Bidirectional Reflectance Distribution Function Factor ƒ′ on the Particulate Backscattering Ratio in an Inland Lake

The bidirectional reflectance distribution function (BRDF) factor ƒ′ provides a bridge between the inherent and apparent optical properties (IOPs and AOPs) of inland waters. The previous BRDF studies focused on ocean waters, while few studies examine inland waters. It is meaningful to improve the theory of remote sensing of water surface and the accuracy of image derivation in inland waters. In this study, radiative transfer simulation was applied to calculate the ƒ′ values using appropriate IOPs based on in situ combined with realistic boundary conditions (N = 11,232). This study shows that ƒ′ factor varied over the range of 0.33–16.64 in Lake Nansihu, a finite depth water, higher than the range observed for the ocean (0.3–0.6). Our results demonstrate that the factor ƒ′ depends on not only solar zenith angle (θs) but also the average number of collisions (n−) and particulate backscattering ratio (b~bp). The ƒ′ factor shows a continuous geometric increase as the solar zenith angle increases at 400–650 nm but is relatively insensitive to solar angle in the 650–750 nm range in which ƒ′ increases as b~bp and n− decreases. To account for these findings, two empirical models for ƒ′ factor as a function of θs, n− and b~bp are proposed in various spectral wavelengths for Lake Nansihu waters. Our results are crucial for obtaining Hyperspectral normalized reflectance or normalized water-leaving radiance and improving the accuracy of satellite products.

Genetic Diversity and Phylogeography of Taenioides cirratus in Five Geographical Populations Based on Mitochondrial COI and Cytb Gene Sequences

The genetic diversity of Taenioides cirratus was investigated on the basis of mitochondrial cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) gene sequences. A total of 159 specimens collected from the Chaohu Lake (CL), Nansihu Lake (NL), Taihu Lake (TL), Pearl River (PR), and Nandu River (NR) were sequenced. The total length of the sequence was 2485 bp with 412 polymorphic sites. A total of 73 haplotypes were identified, with Hap1 being the most widely distributed. The PR and NR populations showed high genetic diversity, while the CL population showed low genetic diversity. TL and NL showed high haplotype diversity but low nucleotide diversity. The analysis of molecular variance demonstrated that the sequence variations were mainly occurred among populations. T. cirratus populations are declining, and rare alleles are present at low frequencies, as analysed using a neutral test and a mismatched distribution analysis. There was a relatively high level of genetic differentiation among the populations of the Yangtze River basin (including NL), PR, and NR (Fst > 0.15). The two similar phylogenetic trees constructed by the maximum likelihood (ML) and Bayesian inference (BI) methods presented three major lineages, of which lineage II contains haplotypes from PR and NR, lineage III contains haplotypes from CL, NL, TL, and PR, whereas lineage I contains only a portion of haplotypes from NR. Based on the neutral test, mismatch analysis, and Bayesian Skyline Plot (BSP), geological and climatic events were inferred to have played an important role in the historical dynamics of T. cirratus population. Hap1, Hap25, and Hap58 were inferred as possible ancestral haplotypes by network analysis. Our study offers an essential foundation for resource preservation and additional taxonomic clarification of T. cirratus.

Optimal Modeling of Sustainable Land Use Planning under Uncertain at a Watershed Level: Interval Stochastic Fuzzy Linear Programming with Chance Constraints

In this paper, an uncertain interval stochastic fuzzy chance constraint land use optimal allocation method is proposed and applied to solve the problem of land use planning in river basins. The UISFCL-LUP method is an aggregation of interval parametric programming, fuzzy linear programming and chance constraint programming which can cope with uncertain problems such as interval value, fuzzy set and probability. In this paper, the uncertain mathematical method is explored and studied in the optimal allocation of land use in the next two planning periods of Nansihu Lake Basin in China. Moreover, it was proved that ISFCL-LUP can deal with the uncertainty of interval, membership function and probability representation and can also be used to solve the land use planning and land use strategy analysis under uncertain conditions. On the basis of model calculations, we obtained the optimal allocation results for six types of land use in four regions over two planning periods based on different environmental constraints. The results show that the optimized λ value (that is, the degree of satisfaction with all the model conditions) is in the range of [0.54, 0.79] and the corresponding system benefits are between [18.4, 20.4] × 1012 RMB and [96.7, 109.3] × 1012 RMB. The results indicate that land managers can make judgments based on the different socio-economic development needs of different regions and determine strategic land use allocation plans under uncertain conditions. At the same time, the model obtained interval solutions under different system satisfaction and constraint violation probabilities, which helps land managers to analyze the importance of land system optimization and sustainable development more deeply.

Effect of physical geographic and socioeconomic processes on interactions among ecosystem services based on machine learning

A thorough understanding of the interactions of ecosystem services (ESs) can enable effective ES planning and management to curtail their degradation and enhance restoration. So it is essential to explore the ecosystem processes and driving mechanisms of ES relationships. Here, the objective of this study is to investigate the mechanisms of multiple ES interactions and provide a decision-making reference for ES management . A dimension reduction to 11 ESs was performed using principal component analysis, and a machine learning approach based on a Bayesian belief network (BBN) was used to identify the effects of physical geographic and socioeconomic processes on ES trade-offs and synergies. Considering the Nansihu Lake Basin, China, as a study area, 11 ESs, namely nutrient retention (nitrogen and phosphorus), aquatic products, habitat quality, pollination , carbon storage, landscape esthetic quality, water yield, food provision, biomass production , and erosion control , mapped in 2018 were quantified. Four principal components, namely synergies between nutrient retention, aquatic production, and habitat quality; synergies between pollination, carbon storage, and landscape esthetic quality; trade-offs between water yield and food provision, biomass production; and erosion control, were extracted from multiple ESs. BBN sensitivity analysis revealed that among the socioeconomic factors (land use type, population density, and night-time light), climate (precipitation, temperature), topogeography (digital elevation model, slope), and soil characteristics (soil types and soil texture), land use exhibits the most critical effect on ES interactions. The response of ES capacities and interactions to land use, climate, and soil management were predicted through BBN scenario analysis, and the results revealed that critical decision-making can optimize multiple ESs. The results of this study can provide a guideline of ES interactions for sustainable management to maximize ES capacities and limit ES trade-offs. • Effect of the physical geographic and socioeconomic processes on ecosystem services were performed. • Dimension reduction to 11 ecosystem services was performed using principal component analysis. • Bayesian Network was used to assess the mechanisms of the interactions among ecosystem services under alternative scenarios. • Interactions among ecosystem services were mainly controlled by land use types, soil and climate factors.

Assessing the Potential Impacts of Urban Expansion on Hydrological Ecosystem Services in a Rapidly Urbanizing Lake Basin in China

Hydrological ecosystem services (HESs) such as water purification and water supply are important for providing other ecosystem services such as drinking water, recreation, and human health. Land use change caused by urbanization is a direct driver affecting the provision of HESs. The quantification and integration of HES into watershed management and urban planning have become increasingly important. In this study, we highlighted an integration of the InVEST and CLUE-S models to simulate and predict future changes of HES in a rapidly urbanizing lake basin, namely the Nansihu Lake basin of China. The spatiotemporal patterns of HESs including water yield, water purification, and sediment export in the past five decades (from 1980 to 2015) have been revealed through our integrated modeling approach. Furthermore, urbanization and land use change scenarios till 2030 were developed using land use, topography, climate, and soil data. It is found that due to the rapid expansion of urban land, water yield, total nitrogen (TN), and total phosphorus (TP) export has increased by 5.5%, 7.38%, and 7.02%, respectively, while the sediment export has decreased by 4%. As a result, the risks of flooding and water quality degradation increased. Under a hybrid ecological and farmland redline policy (EFRP) scenario, the HESs have all been significantly improved compared to the level in 2015. This research can help to predict the future changes in HESs for land use management and ecological and environmental protection in the Nansihu Lake basin.

Dynamic change of land use/land cover patterns and driving factors of Nansihu Lake Basin in Shandong Province, China

Anthropogenic activities and natural factors have a significant effect on land use/land cover (LULC) patterns of Nansihu Lake basin. Understanding the LULC change is essential for regional sustainable development. Based on LULC change detection methods, we characterized the spatial–temporal change of LULC patterns. Logistic regression model and the Conversion of Land Use and its Effects at Small regional extent (CLUE-S) model were used in driving factors analysis and scenario simulation. The results showed that cultivated land and construction land were the dominant LULC types. As construction land gradually expanded to the surrounding areas, a large amount of cultivated land was occupied, especially in the peripheral areas of the central cities. During 1987–2017, 4109.22 km2 of cultivated land was converted into construction land, accounting for 86.38% of cultivated land change, and the contribution rate to construction land was 95.24%. Because of the severe drought in 2002, waters first decreased and then increased. The dynamic degree of waters reached 2.11%, and the increment of waters was mainly converted from cultivated land and unused land. The degree of LULC fragmentation was strengthened, and the distribution showed a diversified trend. The LULC changes were deeply influenced by natural environment and socio-economic factors. Under different scenarios, the expansion of construction land and occupation of cultivated land will continue to be the main features of LULC changes in the future. The LULC patterns will become more regular and more aggregated. This study can help address the interwoven challenges of urbanization development and ecological protection.

Comprehensive application mode of flood and waterlogging control as well as water resources regulation in coal mining subsidence area of Nansihu basin, China

The basin of Nansihu lake is dominated by alluvial plain landform in Shandong Province, China. The region is rich in coal resources and coal mining has formed a large number of subsidence areas. In view of the difficulty of surface water regulation and storage in plain area and the fact that coal mining subsidence area can provide effective storage capacity. The mode of combination of flood, waterlogging control and water resources regulation by using coal mining subsidence area in the basin is put forward. The advantages and disadvantages compared constructing plain reservoirs with using coal mining subsidence area as reservoirs is recognized. The effects of flood control and waterlogging control in coal mining subsidence areas from the scale of watershed and specific cases are analysed. From the perspective of flood and waterlogging control effect, in 2025 and 2035, coal mining subsidence area can reduce the flood of 5% frequency by 12.43% and 34.22% respectively. By 2025, urban waterlogging at 20% frequency will be reduced by 56.19%. In 2035, the ability of coal mining subsidence area to resist urban waterlogging at the same frequency can reach 100%. The coal subsidence area in Longguhu can reduce the flooding at 10%, 5% and 2% frequencies by 15.8%, 12.1% and 9.2%, respectively. It can completely resist the one-day waterlogging in the city at 20% frequency and reduce the waterlogging in the city for three-days by 70.8%. The reconstruction of plain reservoir using the coal mining subsidence area is feasible in technology and engineering construction. But it is still faced with the problem to be solved of the guarantee rate of water supply, water quality etc…

南四湖流域关键生态系统服务的时空权衡关系

从多尺度科学地研究流域各生态系统服务间的权衡与协同关系，对流域实现经济发展与生态保护双重目标具有重要研究意义。运用InVEST模型模拟评估产水量、水质净化、土壤保持、碳存储、生物多样性维持和授粉等6类区域关键生态系统服务，并通过热点分析、相关分析和主成分分析，定量分析自改革开放以来（1980-2018年）这些生态系统服务的时空变化及其在不同尺度上的权衡关系。结果表明：（1）南四湖流域产水服务呈上升趋势，而水质净化、土壤保持、碳储存、生境质量、授粉等服务则总体呈下降趋势。（2）研究区东部林地和草地广布，是碳存储、生境质量和授粉服务的高值区，而建设用地分布的地区是产水量和土壤保持服务的高值区。（3）产水量与水质净化服务之间呈权衡关系，水质净化与生境质量、碳存储与授粉之间则存在较强的协同关系。（4）在子流域尺度上主要是存在着供给服务（产水量）与调节服务（水质净化和土壤保持）、供给服务（产水量）与支持服务（生境质量）之间的空间权衡关系；在县域尺度上，供给服务、调节服务与支持服务（产水量、水质净化、碳存储、生境质量和授粉）之间主要是空间协同关系，两个尺度之间具有较大差异。研究结果可为管理者在合适的空间尺度上制定相应的政策提供科学支撑，促进南四湖流域生态环境和社会经济协同发展。;It is important to create a win-win situation on both economic development and ecological protection. For better ecological management and protection in the future, it is essential to identify the trade-offs and synergies of multiple ecosystem services (ESs) at differently spatial scales. The relationships of ESs varied over time and spatial scales, it is important to study the spatio-temporal dynamics of relationships to realize the trends of ESs change and determine appropriate scale to manage. However, the spatio-temporal dynamics of ESs relationships in the Chinese large basin remain a challenge, as information on adaptable unit to ESs management is often insufficient. Therefore, the purpose of this research is to identify relationships of ESs on sub-watershed and county scales. Six key ESs in Nansihu Basin were selected to simulate and evaluate by InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model since the reform and opening-up (1980-2018), which included water yield (WY), water purification (WP), sediment delivery ratio (SDR), carbon storage (CS), habitat quality (HQ), and crop pollination (CP). In this paper, the spatial distributions of six ESs were analyzed and the hotspots of each ES were identified by hot spot analysis in ArcGIS 10.2. Moreover, the spatial and temporal dynamics of relationships among six ESs were analyzed through correlation and principal component analyses via the correlation and principal component analyses. And further analyses were performed on different scales to the relations. The results displayed as follow:(1) in the Nansi Lake Basin, the WY was increasing from 1980 to 2018, while WP, SDR, CS, HQ and CP were decreasing during this periods. (2) The land use types in eastern basin were mainly forest and grassland, which possessed high levels of CS, HQ and CP. The areas with construction land suggested high levels of WY and SDR. (3) There was a significant trade-off relationship between WY and WP, as well as strongly synergetic relationships between WP and HQ, CS, CP occurred in the basin. (4) There was a great difference in relationships between sub-watershed and county scale. Trade-offs mainly occurred between the provisioning service (such as WY) vs the regulating services (such as WP and SDR) and provisioning service (such as WY) vs the supporting service (such as HQ) on sub-watershed scale. While on the county scale, there was a synergetic relationship between the provisioning service and regulating services vs supporting services (such as WY, WP, CS, HQ, CP). Our research provided an assessment framework to spatio-temporal dynamics of ESs relationships, which suggested that sub-watershed unit was suitable for ecological management. Based on the results of different spatial scales, this research provided scientific support for managers to formulate corresponding strategies at appropriate spatial scale and promote eco-economic coordinated development in the Nansihu Lake Basin.

Spatio-temporal quantification of patterns, trade-offs and synergies among multiple hydrological ecosystem services in different topographic basins

A comprehensive understanding of the spatio-temporal characteristics of interactions and spatial scales of multiple hydrological ecosystem services (HESs) is important for sustainable ecosystem management, but interactions among multiple HESs and their underlying mechanisms in complex socio-ecological systems in different topographic areas remain under-researched. This study discuss the spatial and temporal variation of patterns and interactions of five HESs (biodiversity maintenance, water yield, soil conservation, aquatic purification and water production) in plain and mountain regions to determine synergies and trade-offs at the sub-catchment scale and county scale from 1980 to 2015, and this study employ a case study in the western plain and eastern mountain part of the Nansihu Lake basin in eastern China. The correlation analysis and bagplot analysis were applied to analyze the linkages between HESs, and then redundancy analysis was used to identify important drivers of spatial patterns and interactions of HESs based on socio-ecological variables (e.g., climate, topography, land use, gross domestic product and population density). The results demonstrate that the intercorrelations among HESs varied significantly between the western plain and eastern mountain in both the strength and the direction of the correlating HESs. It was found that there was a trade-off between the water yield and water production in the provisioning services in the eastern mountain basin, while there was no correlation in the western plain basin. Trade-offs and synergies in the entire basin varied greatly over time and space. Compared to the sub-catchment scale, the relationships among the different HESs were mostly weak and some were not significant at the county scale. The study also revealed that topography, land use and climate were the main driving factors affecting the distribution of HESs and their relationships. This study suggested that the sub-catchment scale was more suitable for policy analysts and policy-makers that are concerned with HESs.

Macrozoobenthos variations in shallow connected lakes under the influence of intense hydrologic pulse changes

Hydrologic pulse represent one of the dominant factors controlling the distribution of aquatic organisms. Changes in hydrologic pulses may change the surroundings of the organism and then affect their distribution and community structure. Here, based on the data from a rainy season and a dry season, the water quality, heavy metal in the sediment and macrozoobenthos community structure in two shallow lakes, Nansihu Lake (NSH) and Dongpinghu Lake (DPH, were analyzed. The results showed that the water diversion pulse participated in the influence of runoff pulse on NSH and DPH. The macrozoobenthos community in NSH and DPH were similar after the hydrologic pulse changed, this might be due to these two lakes were connected by the South-to-North Water Transfer Project (SNWTP). Along the direction of water transfer, the macrozoobenthos communities were gradually dominated by small-size species with as water quality decreased. Compared with community structure before the SNWTP, the macrozoobenthos changed from dominant aquatic insect to dominant Mollusca in NSH, and changed from dominant Mollusca and Oligochaeta to dominant Mollusca in DPH. The water diversion pulse, in which the direction of water transfer was opposite to that of natural water flow, affected the distribution of nitrogen and phosphorous in water and heavy metals in sediment. In addition, the introduction of exogenous water caused by the SNWTP changed water quality and heavy metals content in the sediment and water depth in NSH and DPH. These changes together affected the community structure and distribution of macrozoobenthos. These findings enable a better understanding of the ecological impact of intense hydrologic pulse changes caused by water transfer projects.

Comparison of the SWAT and InVEST models to determine hydrological ecosystem service spatial patterns, priorities and trade-offs in a complex basin

• We compared the applicability of InVEST and SWAT in Nansihu Lake basin. • Comparison included the spatial pattern, trade-offs and priorities of three HESs. • The two models provide same reference though some differences in specific values. • Model Users should consider three kinds of conditions and four important factors. Models for the assessment of ecosystem services are important tools for policy-makers and researchers. However, the simulation results of different models vary greatly, and it is difficult for policy-maker to select a suitable model for specific areas. As a result, we compared the results of three hydrological ecosystem services (HESs) in a basin with diverse topography, Nansihu Lake basin, China, including the water supply, soil conservation and water purification services estimated by the Soil and Water Assessment Tool (SWAT) and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. Further comparisons of the HES results were conducted in the application of spatial pattern, priority and trade-off analyses through spatial statistics, hot spot and correlation analyses. Firstly, the results showed that the HES values in whole basin simulated by SWAT model were a little higher than those in InVEST model. Secondly, the spatial patterns of soil conservation service simulated by the two models were approximately similar in whole basin because of proximate simulation algorithm and input data, but the spatial distribution of the other two HESs varied greatly. In particular, the spatial patterns of water supply service simulated by the two models were more similar in hill areas than those in plain areas, while the spatial patterns of water purification service displayed opposite result. Furthermore, the distributions of hot and cold spots of HESs simulated by the two models were approximately consistent. Thirdly, the results of relation analysis to HESs were similar to SWAT and InVEST model roughly. The study suggested that the results of the two models could provide similar frames of reference for management and policy-making although different simulation results between the two models. This research can provide the theoretical basis for model selection, policy decision-making and regional ecosystem management.

Spatio-temporal variation of land use and ecosystem service values and their impact factors in an urbanized agricultural basin since the reform and opening of China.

The provision capacity of ecosystem services is affected by land-use/land-cover (LULC) change and biophysical and socio-economic characteristics. Studies related to ecosystem service values (ESVs) and their impact factors can provide a good reference for natural capital management. In this paper, the temporal and spatial dynamics of LULC and ESVs in the Nansihu Lake basin, China, since the reform and opening of China were analyzed by a combined method of spatial analysis and correlation analysis, and the factors that influence ESV changes were discussed. The results indicated that the main LULC changes were the enormous loss of cultivated land and rapid urban land expansion since the policy of reformation and opening in 1978. The ESVs in the basin decreased by 1.64% (1.70 × 108 US$) from 1975 to 2015, and the main impact factors of this temporal change in ESVs were the changes in waterbodies and cultivated land. Spatial patterns of ESVs were significantly influenced by socio-economic factors in the basin, such as population density and intensity of land use. This research provides alternatives and robust information for policy-making processes for the Nansihu Lake basin, and similar work can be conducted in other parts of the country.

Investigating the Spatiotemporally Varying Correlation between Urban Spatial Patterns and Ecosystem Services: A Case Study of Nansihu Lake Basin, China

Ecosystem services are the benefits obtained from an ecosystem that have great significance in sustainable development. Urbanization has triggered significant changes on urban spatial patterns, which have had a great impact on the ecosystem services. However, studies on the spatiotemporally varying relationship between urban spatial patterns and ecosystem services are lacking. Taking as a case study, the Nansihu Lake Basin in China, this study aimed to explore the spatiotemporally varying relationship between urban spatial patterns and ecosystem services. Urban spatial patterns were derived by integrating remote sensing and spatial metrics. Ecosystem service values were calculated using ecosystem service models. The spatiotemporally varying impact of urban spatial patterns on ecosystem services was quantified using the Geographically Weighted Regression (GWR) model. The findings indicate that urban spatial patterns and ecosystem services have dramatically varied with the urbanization process. The estimated parameters indicate that urban spatial patterns have significant impacts on ecosystem services. The GWR revealed a spatiotemporally varying correlation and improved the explanatory ability in comparison with the Ordinary Least Squares (OLS) model. The investigation of the impact of urban spatial patterns on ecosystem services can provide more practical support for effective urban planning and ecosystem management.

Monitoring spatio-temporal dynamics of habitat quality in Nansihu Lake basin, eastern China, from 1980 to 2015

Rapid industrial development, local urban expansion and intensive agricultural activities directly impact habitat quality and biodiversity. Effective monitoring tools for biodiversity could help assess trade-offs between biodiversity conservation and economic development. Habitat quality is the ability of the ecosystem to support conditions that are suitable for species and is regarded as proxy for biodiversity. This research used the InVEST-Habitat Quality model to monitor the spatio-temporal dynamics of habitat quality in the Nansihu Lake basin from 1980 to 2015; additionally, this research analyzed the potential factors that impacted habitat quality. The results indicated serious habitat degradation in the basin, especially in lake areas, from 1980 to 2015, and the spatial variation in habitat quality decreased extensively, especially from 2005 to 2015. Decreased values of habitat quality in lake areas during past decades suggested that the conservation strategies to natural reserve of lake is not effective. Overall, the habitat quality of most parts of the basin was very low, ranging from 0.10 to 0.20. In addition, only small regions possessed relatively higher habitat quality values, such as hilly areas and lake areas. The spatial patterns of habitat quality were influenced by the physical geographical factors and socio-economic activities. The patterns of habitat quality were significantly related to the physical geographical factors, including DEM (r = 0.50, p < 0.01), slope (r = 0.42, p < 0.01) and NDVI (r = 0.42, p < 0.01), as well as the socio-economic factors, such as land-use intensity (r = −0.88, p < 0.01) and population density (r = −0.32, p < 0.01). The distribution of gross domestic product (GDP) was not correlated with habitat quality. As a surrogate for biodiversity, this approach could be applied for the continuous monitoring of biodiversity in other areas, especially areas that lack biodiversity distribution data; thus, this method can serve as a useful tool for decision makers.

Distribution, pollution status, and source apportionment of trace metals in lake sediments under the influence of the South-to-North Water Transfer Project, China

In an effort to combat the threat of drought, China constructed the South-to-North Water Transfer Project (SNWTP), the biggest water transfer project in terms of volume with the largest beneficiary population in the world. Reports have shown that massive water diversion projects have had detrimental environmental consequences including water quality decline and freshwater habitat degradation. However, few reports have assessed the impact of the transfer project on sediment quality, which is highly susceptible to allogenic and local anthropogenic pollution. We examined the distribution characteristics of Cd, Cr, Cu, Ni, Pb and Zn in surface sediment of the largest reservoir along the East Route of SNWTP, Nansihu Lake, followed by positive matrix factorization (PMF) to determine their potential sources. We utilized enrichment factor, multiple sediment quality guidelines (SQGs), and potential ecological risk index (RI) to determine metal accumulation or pollution risk. The results show the mean concentrations of Cr, Cu, Pb, Zn were slightly lower than in samples collected in 2003, 2010 and 2012, while the mean concentrations of Cr and Ni were significantly higher than samples from previous years. Among the six metals, Cr, Cu and Ni are of higher ecological risk according to SQGs; but Cd is of higher ecological risk according to RI. PMF analysis shows that industrial production and shipping are important sources of Cr, Cu, and Ni. PMF analysis also shows that a considerable amount of trace metals, especially Cd, Cr, Pb and Zn, mainly comes from the use of pesticide fertilizers and biomass sources in farmland, and may partly enter Nansihu Lake from SNWTP. This study reveals the possible sources of trace metals to the Nansihu Lake which is part of SNWTP; the results of the study may serve as a reference for better understanding the impact of future water diversion projects on metals distribution.

Risk assessment of non-point source pollution output in Nansihu Lake Basin based on LUCC

Risk assessment of non-point source pollution output in Nansihu Lake Basin based on LUCC

A new ecological risk assessment index for metal elements in sediments based on receptor model, speciation, and toxicity coefficient by taking the Nansihu Lake as an example

This study focuses on the establishment of a new ecological risk assessment method called as multiparameter evaluation index (MPE) by a combination of speciation, toxicity coefficient, and receptor model of metal elements in sediments and the application of MPE in the assessment of ecological risks of Be, Sb, and Tl in the Nansihu Lake. Because of lack of toxicity coefficient values for Be, Sb, and Tl, their toxicity coefficients were calculated in this study. Speciation analysis showed that Sb had better mobility and bioavailability than Be and Tl. Source apportionment results showed that Be and Sb were mainly from human activities and introduced minerals. Tl was mainly an inherent mineral. MPE results showed that the degree of ecological risk was Be > Sb ≫ Tl. MPE could distinguish the ecological risk levels more accurately than current indices such as RI and RAC.