[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.

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.

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.

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.

[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.

[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.

Friction factor for turbulent open channel flow covered by vegetation.

The need for operational models describing the friction factor f in streams remains undisputed given its utility across a plethora of hydrological and hydraulic applications concerned with shallow inertial flows. For small-scale roughness elements uniformly covering the wetted parameter of a wide channel, the Darcy-Weisbach f = 8(u*/Ub)2 is widely used at very high Reynolds numbers, where u* is friction velocity related to the surface kinematic stress, Ub = Q/A is bulk velocity, Q is flow rate, and A is cross-sectional area orthogonal to the flow direction. In natural streams, the presence of vegetation introduces additional complications to quantifying f, the subject of the present work. Turbulent flow through vegetation are characterized by a number of coherent vortical structures: (i) von Karman vortex streets in the lower layers of vegetated canopies, (ii) Kelvin-Helmholtz as well as attached eddies near the vegetation top, and (iii) attached eddies well above the vegetated layer. These vortical structures govern the canonical mixing lengths for momentum transfer and their influence on f is to be derived. The main novelty is that the friction factor of vegetated flow can be expressed as fv = 4Cd(Uv/Ub)2 where Uv is the spatially averaged velocity within the canopy volume, and Cd is a local drag coefficient per unit frontal area derived to include the aforemontioned layer-wise effects of vortical structures within and above the canopy along with key vegetation properties. The proposed expression is compared with a number of empirical relations derived for vegetation under emergent and submerged conditions as well as numerous data sets covering a wide range of canopy morphology, densities, and rigidity. It is envisaged that the proposed formulation be imminently employed in eco-hydraulics where the interaction between flow and vegetation is being sought.

[Contamination status and speciation for the sediment nutrients in Panjiakou-Daheiting Reservoir]. / æ½˜å¤§æ°´åº“è¡¨å±‚æ²‰ç§¯ç‰©è¥å »ç›æ±¡æŸ“çŠ¶å†µåŠèµ‹å­˜å½¢æ€.

As the source of the "Luanhe-Tianjin Diversion Project", water environment status in the Panjiakou-Daheiting Reservoir directly affects drinking water safety in the water receiving area, and therefore plays important role in the development of the Beijing-Tianjin-Hebei region. Field survey was carried out in July 2016 to examine the pollution status of the sediment nitrogen, phospho-rus and organic matter. The results showed that total nitrogen (TN) content of surface sediments in Panjiakou-Daheiting Reservoir ranged from 1175.41 to 2415.67 mg·kg-1 with a mean of 1648.71 mg·kg-1. Total phosphorus (TP) ranged from 1773.25 to 3471.70 mg·kg-1 with a mean of 2790.89 mg·kg-1. Organic matter (OM) ranged from 6.0% to 25.3% with a mean of 12.5%. Daheiting Reservoir which located downstream of Panjiakou Reservoir had higher value in TP content, while had similar TN content. Results from speciation analysis showed that sediment nitrogen was mainly composed of organic nitrogen and phosphorus mainly consisted of calcium-phosphorus which belonged to inorganic phosphorus. The value of C/N ratio indicated that OM mainly originated from exogenous substances. The pollution assessment results demonstrated that the sediment Panjiakou-Daheiting Reservoir was in a severe pollution status, and might have potential effect to the water environment improvement through the nutrient exchange at the sediment-water interface.

[Relationship Between Macrophyte Communities and Macroinvertebrate Communities in an Urban Stream].

The channelization has caused severe degradation of aquatic ecosystems during the past decades of rapid urbanization in metropolitan areas of China. The re-construction of the in-stream habitat of aquatic organisms and the restoration of aquatic ecosystems were more difficult in the urban stream than in the natural stream with the effluence of nutrient enrichment, water contamination, and in-stream habitat loss. Considering the ecological effects of the submerged macrophyte replantation on macroinvertebrate communities, one of the urban streams that used replantation restoration strategy was seasonally monitored from October 2012 to July 2013. There were four sampling sites, two located at the upper region and two in the middle region. Due to the relatively high levels of organic matter contamination, there are no sites in the downstream region of Qinghe River. Four types of submerged macrophyte were planted at each site to restore the in-stream habitat of two years ago, including Potamogeton pectinatus, Potamogeton crispus, Hydrilla verticillate, and Ceratophyllum demersum. Because of the unexpected development, Myriophyllum spicatum and Acorus calamus appeared at the upper reach of Qinghe River. Considering the average water depth of 30-40 cm, the revised Surber net with the enlarged net was used to collect macroinvertebrate samples. At each sampling site, three replicates of macroinvertebrates were carefully collected for each type of macrophyte. Three replicates were sampled for the comparison at the imperviously concrete sections of each site. The community composition of the macroinvertebrate was determined by cluster analysis and ordination analysis. The density, biodiversity, and community stability were higher in the sampling sections with the replantation of macrophyte than in impervious concrete sections. The occurrence of intermediate tolerant taxa such as Ephemera sp., Caenis sinensis Gui, Ecnomus sp., and Hydropsyche sp. indicated the recovery and restoration of macroinvertebrates in Qinghe River. However, the differences in the community structure, density, taxa richness, biodiversity index, and the composition of functional feeding groups of macroinvertebrates among different types of submerged macrophyte were not identified. Unlike providing extra habitats for macroinvertebrates in the vertical direction in natural streams and lakes, the submerged macrophyte provided more stable benthic habitats in urban streams. The stem and leaf of macrophytes could adjust the hydraulics and continually absorb, fix, and accumulate the suspended solids in the sediment and water interface. The root systems could stabilize the microhabitat of the sediment for macroinvertebrates, benthic algae, and microorganisms. Those aquatic organisms played an important role in the decomposition, transformation, and mineralization of nutrients and organic matter in urban streams. Following the recovery of stabilized microhabitats, community restoration and secondary succession of macroinvertebrates could continually and slowly happen. This study improved the understanding of the ecological effects of macrophytes on the restoration of aquatic organisms and ecosystems in urban streams.

[Estimation of and Control Strategies for Pollution Loads from Non-point Sources in the Chenghai Watershed].

The calculation of non-point source (NPS) pollutant loads of nitrogen and phosphorus is the key step in preparing a pollution control plan. This study modified the export coefficient model by taking into account the precipitation, slope, distance between pollution sources and water bodies, and other relevant factors. The NPS pollution load assessment method established in this study can be applied to data-scarce basins and is suitable for plateau lake regions affected by terrain and precipitation. In this study, Chenghai Lake, which belongs to one of the nine major plateau lakes in Yunnan Province, is selected for the case study. This study first verifies the rationality of the improved export coefficient model based on actual observed values, and then utilizes the improved export coefficient model to assess the loads of dissolved nitrogen (DN) and dissolved phosphorus (DP) pollution. As indicated by the results, in 2014, the loads of DN and DP into Chenghai Lake are 158.48 t·a-1 and 24.70 t·a-1, respectively. The maximum contributions of DN and DP pollution load into Chenghai Lake are from agricultural cultivated land are 46.19% and 48.16%, respectively, in terms of land use. The results present a relatively consistent spatial distribution of DN and DP that indicates that the south bank is a key area for governance. Livestock and rural living are the main pollution sources influencing the load of DN and DP into Chenghai Lake and should be prioritized for control. If the pollution from rural living, livestock, fertilizer loss, and land use can be effectively controlled, the load of DN and DP into Chenghai Lake will be decreased by a maximum of 38.47% and 40.76%, respectively. The results of this study suggest that the improved export coefficient model can be applied for study of the NPS pollution assessment of plateau lake regions and can provide a theoretical basis for the NPS pollution control of the Chenghai Lake basin.