[Health Assessment of the Stream Ecosystem in Beijing, China].

With economic development, the health of river ecosystems is becoming severely threatened because of the increasing effects of human activities on river ecosystems. Here, 101 sites along regional river systems in Beijing rivers were investigated from autumn 2020 to summer 2021. A total of 34 metrics, including aquatic organisms, hydrology, water quality, and habitat, were calculated to be the candidate indicators. Principal component and correlation analyses were used to select the core metrics from the candidate indicators, and the weight of each core metric was estimated using the entropy method. The integrated index of stream ecological health was constructed to assess the health condition of the Beijing rivers. The results of the PCA and correlation analyses revealed that eleven metrics were selected as the core metrics to construct the integrated index of stream ecological health, including water temperature, flow velocity, BOD5, NH4+-N, Cu, the density of phytoplankton and zooplankton, the Shannon-Wiener diversity index of macroinvertebrates and fish, the BMWP index, and the qualitative habitat evaluation index. According to the health assessment results, 4.95% of the sampling sites were healthy, 23.76% were subhealthy, and 71.29% were in a fair or below healthy state. The river health status showed strong spatial heterogeneity, and the river health statuses in the northern and western regions were relatively good, whereas the river health status in the central and southeastern regions were relatively poor. The results of four aspects stream ecosystem assessment showed that the overall water quality of the rivers was "subhealthy" and the aquatic organisms and habitat were "general poor," but the hydrology was "poor." The evaluation results of five water systems demonstrated that the Chaobai River had the best health status, followed by that of the Yongding River, Daqing River, and Jiyun River, and the Beiyun River had the worst health status. Maintaining river ecological baseflow, ensuring river system connectivity, and improving and restoring the river habitat environment are the key aspects of river ecological restoration and protection in Beijing in the future.

Spatiotemporal heterogeneity of inundation pattern of floodplain lake wetlands and impact on wetland vegetation.

The inundation pattern is an important ecohydrological indicator for studying floodplain lake wetlands, as it is the key factor affecting the wetland vegetation distribution patterns. Poyang Lake, the largest freshwater lake in China, is a typical floodplain lake wetland. This study presents a hydrodynamic model and vegetation survey of Poyang Lake, analyzed the spatiotemporal heterogeneity of the inundation pattern (inundation duration and depth), assessed the response patterns of wetland vegetation concerning the inundation pattern, and examined the impact of the proposed Poyang Lake Water Conservancy Hub (PLWCH) on the inundation pattern and wetland vegetation. The results revealed that the inundation pattern of Poyang Lake had significant spatial heterogeneity. Inundation pattern was found to have a significant impact on the vegetation succession. The response relationship between the distribution areas of different wetland vegetation types and inundation pattern was in accordance with the Gaussian curve, and the ecological threshold range of the Carex spp. community was the greatest. Owing to factors such as climate change and anthropogenic activities, the inundation pattern of Poyang Lake varied significantly since 2003, with the average inundation duration and average inundation depth decreasing by 15 d and 0.32 m, respectively. Consequently, the spatial distribution of wetland vegetation changed significantly, whereby the Carex spp., Polygonum criopolitanum, and Phalaris arundinacea communities extended down to the lower elevation zone. In the future, the PLWCH may result in increases in the inundation duration and depth, restrain the downward vegetation extension trend, and promote the vegetation to move to higher elevations similar to the status prior to 2003. These findings provide a detailed description of the spatiotemporal heterogeneity of the inundation pattern and the drivers of wetland vegetation distribution patterns in floodplain lake wetlands, serving as a scientific basis for conservation and restoration of these ecosystems.

Bayesian-based calibration for water quality model parameters.

To improve the efficiency and accuracy of water quality model parameter calibration and avoid local optima and the phenomenon in which different parameters have the same effect, this paper proposed a novel Bayesian-based water quality model parameter calibration method. Using Bayesian inference, the parameter calibration problem was converted into a posterior probability function sampling problem, which was sampled using the Markov Chain Monte Carlo algorithm. The convergence speed of the calibration was further improved by setting the optimized initial sampling value. The influences of the initial sampling value, Markov chain length, and proposal distribution form on the calibration effect were evaluated using four specific cases. The results indicate that (1) the mean relative error (MRE) of the parameter calibration results of this method is less than 10%, with the calibration MRE of Dx and Dy being 5.3% and 8.3%, respectively; (2) when the parameter sensitivity is low, the calibration effect of this method is relatively poor, with a calibration MRE of 46% for k; (3) the parameter calibration can be completed more efficiently by setting an optimized initial value for the MCMC, choosing a reasonable Markov chain length and a suitable proposal distribution form. PRACTITIONER POINTS: Bayesian-based water quality model parameter calibration method is proposed and posterior probability distribution was sampled using the MCMC algorithm. Parameter calibration can be completed more efficiently by setting an optimized initial value for the MCMC. As a result, efficient and accurate parameter calibration of water quality models was achieved. This method is widely applicable to various models, and the calibration speed depends on the calculation speed of the model.

Calculation and evaluation of suitable ecological flows for eco-environmental recovery of cascade-developed rivers.

River cascade development affects the hydrological and habitat characteristics of the region and disrupts the dynamic balance of stable river ecosystems. The most profound impact of river cascade development is on the resident fish species. River ecosystem restoration for maximum river habitat improvement is generally based on water security and environment improvement and effectively embodies the nature-based solutions (NbS) concept of naturalized restoration. Yuanjiang (Y.J.) River is an international river in southwest China seriously affected by cascade development. By determining the response of the river ecosystem and using the key performance indicator method, Yuanjiang carp (Cyprinus carpio rubrofuscus) and red giant catfish (Bagarius rutilus) were identified as the key species in the main stream of the Y.J. River., and the ecological effects of river cascade development on them were studied by applying two-dimensional hydrodynamic physical habitat simulation and multi-objective ecological scheduling models. Based on the calculation results for ecological operation optimization of cascade reservoirs, an improved progressive optimality algorithm was used to calculate the ecological flows required to maintain the stability of the river ecosystem. With the increasing extent of cascade development in the river, important indicators, such as the intra-annual, extreme, high, and low flows have changed significantly, and the hydrological characteristics of the main stream have changed rapidly and comprehensively. Habitat suitability curves were used to determine the appropriate water depth and delineate the weighted usable area required for the spawning, nursing, and growing periods of the key fish species. The suitable ecological flows required for the three life-cycle stages of the C. carpio rubrofuscus accounted for 34, 45, and 62 %, respectively, of the multi-year mean natural water inflow at the Qiaotou (Q.T.) cascade, whereas those required for the three respective periods of B. rutilus accounted for 47, 98, and 27 %, respectively, of the multi-year mean natural water inflow at the Madushan (M.D·S.) cascade. Considering the physiological lifecycle demands of the indicator/key fish species and the upper limit of water resources development and utilization in the key river section, the ecological flow precipitation frequency in the Q.T.-Luodie (Q.T.-L.D.) and M.D·S.-Xinjie (M.D·S.-X.J.) sections (currently at 25, 50, and 75 %, respectively) can be increased to 100 % under optimal operating conditions (cascade hydropower station optimal operation). After implementing the multi-objective ecological operation at the Y.J. River main-stream cascade reservoirs, the suitable habitat area for C. carpio rubrofuscus and B. rutilus increased significantly (>10 % and 15 %, respectively). In general, the NbS-based ecological flow calculation method for cascade-developed rivers has a wide range of applications, which can be useful for the eco-environment restoration of rivers and improving the living habitats of waterway organisms.

Clinical study on prevention of atopic dermatitis by oral administration of probiotics in infants.

Introduction: This study aimed to investigate the preventive effects of oral administration of probiotics on the incidence and severity of atopic dermatitis (AD) in infants. Material and methods: A total of 396 full-term infants were enrolled in this study. Of these, 132 newborns without a family history of AD were assigned to group A, and the other 264 newborns were randomly divided into groups B and C. Infants in groups A and B were solely breastfed, while probiotics were administered to those in group C as well as breastfeeding. The information of all subjects was recorded, and the incidence of AD was followed up. The levels of serum IgE and IL-4 were measured at the age of 3 years. Results: The incidence of AD in infants in group B was higher than that in group A at 3 months, 4-6 months, and 7-36 months after birth, together with increased symptom scores. For infants in group C, the incidence of AD at 4-6 months and 7-36 months after birth and the SCORAD scores at 0-3 months and 4-6 months after birth were lower than those in group B. The levels of IgE and IL-4 in group B were higher than those in groups A and C at 36 months old. Conclusions: Adding probiotics could favor the establishment of the intestinal microecological balance in the neonatal period, thereby reducing the incidence of AD, decreasing the levels of serum immune indexes and alleviating the severity of the disease.

Understanding the relative roles of local environmental, geo-climatic and spatial factors for taxonomic, functional and phylogenetic ß-diversity of stream fishes in a large basin, Northeast China.

The primary objective of this study was to determine the relative roles of local environmental (Local), geo-climatic (Geo), and spatial (Spatial) factors to taxonomic, functional, and phylogenetic ß-diversity of stream fish in a large basin in Northeast China. We quantified the current biodiversity patterns of fish communities in the Hun-Tai River using ß-diversity. We assessed (i) corresponding contributions of turnover and nestedness within the taxonomic, functional, and phylogenetic ß-diversity of fishes; (ii) correlations among ß-diversity facets (i.e., taxonomic, functional, and phylogenetic facets); (iii) relative contributions of Local, Geo, and Spatial factors to ß-diversity. We collected fish communities from 171 sampling sites. Mantel tests were used to examine the correlation of three facets of ß-diversity and their components (i.e., total, nestedness, and turnover). Distance-based redundancy analysis and variation partitioning assess the relative contributions of Local, Geo, and Spatial factors to ß-diversity. We found that turnover is the main driving mechanism for ß-diversity in fish. Among the facets of ß-diversity, taxonomic and phylogenetic facets have strong ecological information association. Spatial factors have a general contribution to various facets of ß-diversity and its components. From aspects of fish ß-diversity conservation, connectivity and habitat heterogeneity need to be maintained in the entire aquatic environment. In addition, protecting taxonomic ß-diversity is helpful for maintaining phylogenetic ß-diversity.

Spatial Factors Outperform Local Environmental and Geo-Climatic Variables in Structuring Multiple Facets of Stream Macroinvertebrates' ß-Diversity.

One of the key targets of community ecology and biogeography concerns revealing the variability and underlying drivers of biodiversity. Most current studies understand biodiversity based on taxonomic information alone, but few studies have shown the relative contributions of multiple abiotic factors in shaping biodiversity based on taxonomic, functional, and phylogenetic information. We collected 179 samples of macroinvertebrates in the Hun-Tai River Basin. We validated the complementarity between the three facets and components of ß-diversity using the Mantel test. Distance-based redundancy analysis and variance partitioning were applied to explore the comparative importance of local environmental, geo-climatic, and spatial factors on each facet and component of ß-diversity. Our study found that taxonomic and phylogenetic total ß-diversity was mainly forced by turnover, while functional total ß-diversity was largely contributed by nestedness. There is a strong correlation between taxonomic and phylogenetic ß-diversity. However, the correlations of functional with both taxonomic and phylogenetic ß-diversity were relatively weak. The findings of variation partitioning suggested that distinct facets and components of macroinvertebrates' ß-diversity were impacted by abiotic factors to varying degrees. The contribution of spatial factors was greater than that of the local environment and geo-climatic factors for taxonomic, functional, and phylogenetic ß-diversity. Thus, studying different facets and components of ß-diversity allows a clearer comprehension of the influence of abiotic factors on diversity patterns. Therefore, future research should investigate patterns and mechanisms of ß-diversity from taxonomic, functional, and phylogenetic perspectives.

Influence of shrub root combinations and spacing on slope stability: study case at the Yongding River flooding regime, Langfang, China.

Research on the mechanism of plant root-soil consolidation is a current focus in research into the ecological restoration of banks. The stability of ecological banks is central to this research, and bank stability is closely related to plant combinations and spacing. Recent research on reinforced anchorage of plant roots has mainly focused on root length and angle, and on other parts of the root system, and only a few studies have examined the combination of different types of roots. In this study, a coupled slope stability assessment system is created, composed of root morphological parameters and involving calculations using the finite element model ABACUS. This paper selects the two banks of the lower reaches of the Tiantang River in the flood zone of Yongding River as the research area, and examines slope surface plants. And then the reinforcement effect of different shrub roots combinations and plant spacing are evaluated for determining the optimal shrub layout, with the aim of solving the instability problem of collapsible silty clay bank slopes and associated risks. The results indicated that when the shrub plant spacing is 0.65 m, the optimal shrub combination is Tamarix chinensis + Philadelphus incanus, and when the shrub plant spacing is 0.75 m, the optimal shrub combination is Tamarix chinensis + Euonymus alatus. The study found that the root system morphology and the fibrous roots amount at the foot of the slope can have different degrees of influence on the shallow soil stability of the silty clay slope under different shrubs plant spacing conditions.

Prevalence and factors associated with compassion satisfaction and compassion fatigue among Chinese oncology healthcare professionals: A cross-sectional survey.

Objective: This cross-sectional study examined the prevalence and factors associated with compassion satisfaction and fatigue among oncology healthcare professionals (doctors and nurses) in mainland China. Methods: A total of 337 subjects were recruited via convenience sampling from the oncology departments of five general hospitals in Guangzhou, Guangdong, China. They were invited to complete a survey that included demographic characteristics, the Profession Quality of life Scale, the Brief Cope Questionnaire, and the Connor-Davidson Resilience Scale. Results: The findings showed medium levels of compassion satisfaction, burnout, and secondary traumatic stress among oncology healthcare professionals in China, reaching rates of 78.34%, 63.50% and 75.96%, respectively. Multiple regression analyses suggested that active coping, positive reframing, and strength were the significant factors of compassion satisfaction, explaining 48.6% of the total variance (P â€‹< â€‹0.001). Substance use and self-blame were the significant factors of burnout, explaining 45.1% of the total variance (P â€‹< â€‹0.001). Venting, denial, substance use, self-blame, and strength were the significant factors of secondary traumatic stress, explaining 37.6% of the total variance (P â€‹< â€‹0.001). Conclusions: The high prevalence of compassion fatigue warrants the attention of the hospitals' senior management. The effective coping styles identified may be considered when developing strategies to improve the professional quality of life among oncology healthcare professionals.

Quantitative analysis of ecological suitability and stability of meandering rivers.

BACKGROUND: As the most widely distributed river form in the world, meandering river is of great significance for stabilizing the physical structure of the river and maintaining ecosystem. To quantitatively study the positive effects of meandering rivers, the Chishui River, a natural tributary of the Yangtze River in Southwest China, is selected as the research area, and two typical river sections with different meandering degrees are selected as the research objects. METHODS: Based on the field survey data, the local endemic fish Procypris rabaudi (Tchang) is considered the object fish, and a hydrodynamic model was used to simulate the distribution of water depth and flow velocity in certain river reaches at different flows. By introducing the weighted usable area (WUA) and hydraulic unit diversity index, combined with the suitability curves of the study species, the hydraulic characteristics and habitat suitability changes of two river reaches under different flows are summarized and analyzed, and the hydrogeomorphological process of the studied river section is generalized. RESULTS: With the change in discharge, a positive correlation is observed between the maximum velocity and depth of the meandering river and the discharge, whereas the WUA and hydraulic unit index of the meandering river have relatively small changes. Under low discharge, the distribution of pool-riffle sequences can be seen in the meandering reach, which is essential to improve the ecological suitability and stability of the river. CONCLUSIONS: This study provides scientific sustentation for river restoration and fish conservation.

Influence of catastrophic flood on microplastics organization in surface water of the Three Gorges Reservoir, China.

The Three Gorges Dam (TGD) is the world's largest hydropower project. It could potentially influence the footprint and transport of microplastics (MPs) in Yangtze River, which is the largest riverine input of oceanic MPs worldwide. In addition to analyzing the MP particles of all size categories and polymer groups, we also evaluated the stability, pollution risk and source identification of MPs after the catastrophic flood of 2020 in the Three Gorges Reservoir (TGR) and downstream of the TGD. We found that the MP abundance (6214 ± 5394 particles/m3) in the TGR water increased by a 57.9% growth after this catastrophic flood. Interestingly, we observed the small-sized MPs (SMPs; < 300 µm) were dominant in the TGR (accounting for ∼65.4% of the total MP particles). After flooding, the main morphological types were fragment and fiber, while the major polymer was polyethylene (PE). Although the MP level was at a low pollution risk, 13.6% of the sampling sites in the TGR water faced potential ecological risks driven by SMPs. In particular, there was no significant difference in the abundances, morphological types, and polymer composition of MPs between upstream and downstream of the TGD (p > 0.05), indicating flooding control operation could weaken the barrier effect of the dam on MPs. Further, based on the conditional fragmentation model, the PE fragments in SMPs of the TGR remained at a stable state. MPs in the TGR mainly originated from anthropogenic activities (wastewater, containers, and agriculture films), with atmospheric deposition as a potential transport pathway for polymers. Our study demonstrates that dam operation during the flood period can influence the MP organization in TGR, providing new insights of the global land-sea transportation of MPs in the Yangtze River.

Occurrence, stability and source identification of small size microplastics in the Jiayan reservoir, China.

Microplastics (MPs) in terrestrial aquatic ecosystems has received increasing attention. However, its footprints in reservoirs are poorly documented compared to those in rivers and lakes, especially for small-sized microplastics (<300 µm, SMPs). This study investigated the whole size spectrum of MPs contamination, classified by shape and polymer type, in surface waters and sediments at the Jiayan reservoir, one of the cascade reservoirs in the Upper Yangtze River in western China. High concentrations of MPs were detected in all surface water and sediment samples. The MPs abundances ranged from 1.10 × 104 to 6.17 × 104 items/m3 (average 2.75 × 104 ± 2.33 × 104 items/m3) in the surface water and 2.60 × 103 to 1.57 × 104 items/kg (average 6.90 × 103 ± 5.96 × 103 items/kg) in the sediment. The SMPs accounted for 80% of the total MPs particles, and were dominated by polyethylene (PE) fragment. Small-sized PE was the main contributor to the high abundance of MPs in the Jiayan reservoir. Neglecting SMPs not only leads to an underestimation of the degree of risk, but also causes misjudgment of the major morphology, components, and sources. The conditional fragmentation model analysis showed the stability of MPs increased from the fibers to fragments and fibers tend to disintegrate into smaller particles. Agricultural activities and atmospheric deposition were the main sources of MPs in the Jiayan reservoir. This study indicates that the reservoirs are presumably hotspots for MPs accumulation, and the fate of SMPs in the cascade reservoirs deserves more attention for further studies.

Interactive influences of ecosystem services and socioeconomic factors on watershed eco-compensation standard "popularization" based on natural based solutions.

Watershed eco-compensation is a policy tool to realize watershed environment improvement and regional economic development. It is important to eliminate the influence of economic differences between upstream & downstream regions and realize the fairness of regional social development based on Natural based Solutions (NbS). At present, lack of clarity in coupling and coordination analysis of ecosystem services & socioeconomic based on NbS could hamper watershed eco-compensation standards "popularization" and reduce the ability to successfully ecological governance. To meet the needs of economic development and ecological service value realization, dynamic equilibrium game research based on multidimensional relationship coordination and a multi-objective optimization solution of economic benefit distribution was carried out. To achieve the bargaining Bayesian/Nash equilibrium of the watershed eco-compensation standard in the game, the existence conditions of the equilibrium solution of the eco-compensation standard based on the mixed equilibrium game implementation process were studied. To carry out the complete information dynamic game, the equilibrium solution of the watershed eco-compensation standard based on the dynamic transfer payment was solved, and the rational analysis of the dynamic Bayesian equilibrium game of bargaining based on the incentive compatibility mechanism was also discussed. Water quantity and quality eco-compensation can ensure balanced development between ecological protection and the social economy in the Mihe River Basin. Combined with the variation law of socioeconomic water intake-utilization standards and the water use value, the city of Shouguang City & Qingzhou City should pay Linqu County 4.78 million US$ and 1.29 million US$ as watershed eco-compensation standards per year based on NbS, respectively. To verify the rationality of the results derived from the economically optimal model, two modes of "bargaining" & "perfect competition", were used to study the characteristics of the protocols generated by the equilibrium game, and the applicable conditions of the nonzero-sum game solution upstream and downstream of the watershed were also explored. Based on the nonzero-sum processing of the survey results, the current relationship between the input value of eco-compensation and the willingness to pay satisfies v ≥ c + 1 / 4 . Based on the dynamic game & Bayesian equilibrium solution of bargaining, the watershed eco-compensation quota of water quantity & quality is 6.07 million US$, the willingness to pay is 65.63 US$/month. These findings contribute to the quantifying process of bargaining & dynamic equilibrium by transforming "ambiguous" information to achieve sustainable ecosystem service management and develop socioeconomic strategies associated with different compensation features based on NbS, thus helping to inform watershed management.

Contamination of Proteus mirabilis harbouring various clinically important antimicrobial resistance genes in retail meat and aquatic products from food markets in China.

Proteus mirabilis is an opportunistic pathogen frequently associated with nosocomial infection and food poisoning cases. Contamination of P. mirabilis in retail meat products may be important transmission routes for human infection with P. mirabilis. In this study a total of 89 P. mirabilis strains were isolated from 347 samples in 14 food markets in China and subjected to whole-genome sequencing. Phylogenetic analysis showed that all 89 strains were divided into 81 different clones (SNPs >5), indicating high genetic diversity of P. mirabilis in food markets. Antimicrobial susceptibility testing showed that 81 (91.01%) strains displayed multidrug resistance profiles. Seventy-three different resistance genes (or variants) were found, including various clinically important antimicrobial resistance genes aac(6')-Ib-cr (77.53%), bla CTX-M (39.33%), fosA3 (30.34%), as well as multiresistance gene cfr (4.50%), tigecycline resistance gene cluster tmexCD3-toprJ1 (4.50%) and carbapenemase gene bla NDM-1 (1.12%). Diverse genetic elements including Tn7 transposon, plasmid, SXT/R391 integrative conjugative element were associated with the horizontal transfer of cfr. tmexCD3-toprJ1 and bla NDM-1 were located on ICEPmiChnJZ26 and Salmonella genomic island 1, respectively. Our study emphasized high contamination of P. mirabilis harbouring various clinically important antimicrobial resistance genes in retail meat and aquatic products, which might be an important issue in terms of food safety and human health.

[Temporal-spatial distribution and ecological evaluation of macroinvertebrate functional feeding groups in Yongding River Basin]. / æ°¸å®šæ²³æµåŸŸå¤§åž‹åº•æ –åŠ¨ç‰©åŠŸèƒ½æ‘„é£Ÿç±»ç¾¤æ—¶ç©ºåˆ†å¸ƒåŠç”Ÿæ€è¯„ä»·.

We investigated community structure of macroinvertebrate, water environment factors, hydrological factors at 23 sampling sites of the Yongding River basin from spring 2017 (April) to autumn 2017 (November). We analyzed the composition, spatial and temporal distribution of the macroinvertebrate functional feeding groups, as well as their responses to changes in riverine habitat. A total of 78 macroinvertebrate species were identified, with 52, 50 and 53 macroinvertebrate species in spring, summer and autumn respectively. The dominant functional feeding groups were gather-collectors, followed by predators, while the proportion of scrapers, filter-collectors and shredders were extremely low. Dominant species in the three seasons were all gather-collectors, including Orthocladius, Rheotanytarsus, Cricotopus in spring, Glyptotendipes in summer, and Polypedilum, Chironomus, Orthocladius in autumn. Results of redundancy analysis showed that the functional feeding groups of macroinvertebrate community structure were mainly influenced by water temperature, flow velocity, salinity, and total phosphorus in spring, by total phosphorus, dissolved oxygen, conductivity and flow capacity in summer, and by total phosphorus and dissolved oxygen in autumn. Total phosphorus had positive correlation with gather-collectors in all three seasons, indicating that the functional feeding groups of macroinvertebrates were affected by water pollution. The evaluation based on the metrics of functional feeding groups showed that: 1) in terms of material cycle, primary productivity of Guishui River were significantly higher than other regions, and that in autumn were significantly higher than other seasons. The secondary productivity and decomposition capacity of Yanghe River were significantly higher than other regions, and those in spring were significantly higher than other seasons. The autotrophy/heterotrophy of Yanghe River was significantly lower than other regions, and that in spring were significantly higher than other seasons. 2) The longitudinal transport capacity of Sanggan River was significantly higher than other regions, and that in autumn was significantly higher than other seasons. 3) The lateral input capacity of Guishui River was significantly higher than other regions, and that in summer was significantly higher than other seasons.

Modeling the impacts of plants and internal organic carbon on remediation performance in the integrated vertical flow constructed wetland.

The integrated vertical flow (IVF) constructed wetland consists of two or more chambers with heterogeneous flow patterns and strong aeration capability, possesses favorable remediation performance. The Constructed Wetland Model No.1 (CWM1) embedded in the OpenGeoSys # IPHREEQC was applied to investigate the wetland plant effects on treatment efficiency. Two fundamental functions of the plant roots (i) the radial oxygen loss (ROL) and (ii) exudation of internal organic carbon (IOC), are developed and implemented in the model to simulate the treating processes of planted laboratory-scale IVF wetlands fed by the synthetic wastewater. The good agreement between simulated results and measurements of the planted IVF wetland and the unplanted filters mimicking wetland demonstrates the combined effects of ROL and IOC and the model reliability. In summer the ammonia (NH4-N) and total nitrogen (TN) removals are high as above 90% in both IVF wetlands, and in winter they decline significantly to around 55% and 45% in unplanted wetland, contrastively to about 85% and 78% in the planted wetland. The nitrogen removal - COD/N ratio relation curves of IVF wetlands are proposed and obtained by modeling to evaluate organic carbon loading status. Based on the curves, the COD/N ratios of unplanted and planted wetlands are about 3∼7 and 3∼10 gCOD/gN for high TN removal respectively. Planted wetlands can tolerate a wider range of COD/N ratio influents than unplanted ones. The ROL in the unplanted wetland promotes COD and NH4-N removal, while may inhibit denitrification under low-temperature conditions. The single addition of IOC enhances the oxygen-consuming and restrains the nitrification under the full loaded COD condition. Summing up all organic carbon releases from substrate and roots as IOC, the quantification of IOC acts on nitrogen treatment was simulated and compared with the external organic carbon (EOC) loading from influent. IOC performs higher efficiency on TN removal than EOC at the same organic loading rates. The results provide the thoughts of the solution for low TN removal in the carbon deficient constructed wetlands.

[Spatial Differences in Water Quality and Spatial Autocorrelation Analysis of Eutrophication in Songhua Lake].

To identify the spatial differences in the water quality and eutrophication characteristics of Songhua Lake, the largest artificial lake in northeast China, analysis of variance (ANOVA) and factor analysis were used to analyze the water quality sampling and testing results in 2017 in three regions, namely the main reservoir area of the Fengman Reservoir (MRAFR), the experimental area of the Songhua River Three Lakes Protection Zone (EASRTLPZ), and the Jiaohe River backwater area (JRBA). The nutrient status of the lake was evaluated by the trophic state index method, and the spatial correlation and aggregation status of the eutrophication level in Songhua Lake were studied using spatial autocorrelation analysis. The main results were as follows: ① the ANOVA showed that, except for dissolved oxygen and chlorophyll-a (Chl-a), there were significant differences (P<0.05) in the total nitrogen (TN), total phosphorus (TP), water temperature (WT), and pH in the three areas of Songhua Lake, with the clearest difference between TN and TP. ② The factor analysis showed that the changes in the climatic condition factor (WT), nutrient salt factors (TN and TP), and algal biomass factor (Chl-a) dominated the water quality in the lake. ③ The results of the trophic state index showed that the nutrient status of Songhua Lake as a whole is mildly eutrophic, and the eutrophication levels of the three regions from strong to weak are JRBA > MRAFR > EASRTLPZ. ④ The global spatial autocorrelation showed that the eutrophication level of the lake as a whole has significant positive spatial autocorrelation owing to the influence of regional eutrophication levels. The spatial heterogeneity of the eutrophication level of Songhua Lake is low. ⑤ The results of the local spatial autocorrelation showed that the central and northern areas of JRBA are the hot spots (high/high concentration) of eutrophication in the lake (P<0.01), and the central part of EASRTLPZ is the cold spot (low/low concentration) of eutrophication in the lake (P<0.05). Therefore, when conducting water environmental management of Songhua Lake, the key areas for eutrophication control should be the JRBA and MRAFR.

Stochastic trophic level index model: A new method for evaluating eutrophication state.

The trophic state index (TSI) and trophic level index (TLI) are commonly used methods for evaluating the eutrophication state of lakes and reservoirs. However, they are unable to overcome uncertainties such as calculation errors and spatial heterogeneity of evaluation indicators. To comprehensively evaluate the eutrophication state of a region, we introduce a probability density function and propose the stochastic trophic level index model (STLI). The probability density function of each trophic level is derived through the principle of maximum entropy, and membership vector F (F1, F2, F3, F4, F5) for each trophic level is established to quantify the risk of regional eutrophication. We utilized STLI to evaluate the eutrophication status of Songhua Lake, China, and determined that the method can be used for uncertainty and risk assessment. Our results show that the Jiaohe River backwater area has the highest eutrophication level (light eutropher), with a 0.12 probability of further deterioration to middle eutropher. The eutrophication status of the Main Scenic Area of the Songhua Lake Scenic Resort was shown to be mesotropher, with 0.26 and 0.08 probabilities of further deterioration to light eutropher and middle eutropher, respectively. Finally, the eutrophication status of the Songhua River Three Lakes Reserve Experimental Area was shown to be mesotropher, with a 0.24 probability of further deterioration to light eutropher. Overall, the Songhua River Three Lakes Reserve Experimental Area is the most promising for the lowest level of eutrophication. We recommend that the management department take effective targeted measures against the Jiaohe River backwater area first. The probability density and membership vector of STLI can effectively solve the uncertainties presented by traditional methods for evaluating regional eutrophication status.

[Distribution pattern of macroinvertebrate community and its relationships with environmental factors in the Yongding River Basin]. / æ°¸å®šæ²³æµåŸŸå¤§åž‹åº•æ –åŠ¨ç‰©ç¾¤è½åˆ†å¸ƒæ ¼å±€åŠå ¶å½±å“å› å­.

Human disturbances have altered global stream ecosystems in multiple ways. Understan-ding spatio-temporal dynamics of aquatic organism composition and their relationships with environmental factors play an important role in revealing changes in the structure and function of river ecosystems. The macroinvertebrates and environmental parameters were sampled in the Yongding River Basin at spring (March), summer (July), and autumn (November) in 2017. The results showed that chironomids were the dominant group in the Yongding River Basin, including Orthocladius, Chironomus, Glyptotendipes, and Polypedilum. Results of the cluster analysis showed significant spatial variations of macroinvertebrate community. Sampling sites were clustered into two groups based on the similarities of macroinvertebrate composition in the Yongding River. Sampling sites belonging to group 1 mainly located in the Sanggan River and Dongyang River, with Orthocladius sp.being the dominant species. Sampling sites belonging to group 2 mainly located in the Yang River, Guishui River and main section of the Yongding River, with Glyptotendipes sp. being the dominant species. The biomass, Shannon index, Margalef index, Pielou evenness index and taxa richness of group 2 were significantly higher than those of group 1. Higher values of biological indices indicated better ecological condition of the stream ecosystem. The density, biomass and diversity indices of summer were significantly lower than those of both spring and autumn. Results of Canonical correspondence analysis (CCA) showed that the spatio-temporal distribution of macroinvertebrate in the Yongding River was mainly influenced by water temperature, ammonium, pH, dissolved oxygen, and total phosphorus. From the perspective of hydrological characteristics, flow velocity and flow capacity were significantly correlated. The significant positive correlations between hydrological parameters of velocity and capacity and biological indices of density and EPT% in group 2 indicated the preference of fast flow to sensitive taxa of EPT (Ephemeroptera, Plecoptera, and Trichoptera). The negative correlations between flow capacity and biodiversity indices implied the adverse effects of high flow on macroinvertebrate biodiversity. Our results confirmed that the composition and biodiversity of macroinvertebrate were affected by both water environment and hydrology, which reflected the multiple human activities in aquatic ecosystems of the Yongding River. It is important to control water contamination and sustain environmental flow at the specific reaches for the restoration of Yongding River.

Boron toxicity coefficient calculation and application for ecological risk assessment in reservoir sediments.

B is a potentially toxic element, and its potential ecological influences in aquatic environments have gained increasing attention in recent years, especially in reservoir ecosystems. As the largest freshwater reservoir in China, the estimation of B's ecological risks in the Three Gorges Reservoir (TGR) is critical for national drinking water safety. However, the lack of a toxicity coefficient (Tc) for B limits its ecological risk assessment (Er) in aquatic environments, especially for sediments. In this study, the Tc of B was carefully calculated, considering toxicological, sedimentological, and ecological ranking factors. The Er for B was then assessed for surface sediments collected from the TGR. Enrichment factors (EFs) were also used to identify the influence of human activities on B. The results show that the average concentrations of B in mainstream and tributary sediments were 53.98 mg/kg and 90.88 mg/kg, respectively, slightly higher than sediment background B values in China (48 mg/kg). Additionally, EFs showed that the tributary sediments were moderately enriched in B. The EF 1.5 value was higher than zero, indicating that the anthropogenic influence in tributary sediments than in mainstream sediments. Moreover, chemical speciation of B in TGR sediments was mainly attributed to the residual fraction, indicating weak migration of B in sediments. Furthermore, after calculating Tc according to the principles of Er, it was found that it is more scientific to assign the Tc of B in sediments a value of 2. Based on this Tc value, the Er in the TGR was assessed and it revealed that B in TGR sediments had low ecological risk. The scientific calculation of the Tc provides an important parameter for B ecological risk assessments in aquatic environments in the future.