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With the implementation of the South-North Water Diversion Project and the implementation of groundwater suppression, the local groundwater levels in the North China Plain have gradually rebounded. However, there is a lack of systematic studies of the trends of groundwater balance elements and their impacts on the ecological environment. This paper takes the Baoding Plain, a typical area in the North China Plain, as an example, and uses the water balance method to calculate the groundwater recharge and discharge terms, applies the factor analysis method to analyze the causes of the changes in groundwater balance elements from 1975 to 2019, and calculates the amount of recoverable and suppressed groundwater resources by using the optimal exploitation coefficient method, which provides a basis for the development and utilization of groundwater resources in the study area. The results show that in the past 40 years, the groundwater recharge term was smaller than the discharge term in the Baoding Plain, which is in a negative equilibrium state, and the main change elements are canal irrigation infiltration, canal system seepage, well irrigation return, river seepage, rainfall infiltration and artificial exploitation. The main factor affecting the change of groundwater equilibrium elements is human activity, with a contribution rate of 77.2%. After the groundwater recharge and discharge imbalance is slowed down, the increase of groundwater level burial depth becomes smaller, the area of groundwater level depression cone gradually decreases, and the area of the Baiyangdian wetland gradually recovers. The optimal exploitation coefficient of groundwater resources in the Baoding Plain is determined to be 0.64, the exploitable groundwater resources range from 8.89×108 to 11.35×108 m3/a, and the amount of compression exploitation ranges from 2.68×108 to 5.14×108 m3/a. The research results can provide a scientific basis for the sustainable development of groundwater resources and ecological environment in similar areas.

In arid and semiarid regions, lake-basin ecosystems are an important part of watershed security barriers, playing an important role in maintaining the stability of ecological patterns. However, the ecological environment of the lake-basin system has been gradually degraded in recent years, and its change process is accompanied by a complex dynamic mechanism. In the present study, we explored the spatial variability of the ecological environment of the lake-basin system and its drivers by taking Baozhainao Lake in the Mu Us Sandy Land of the Ordos Basin as the study area.In-situ dynamic monitoring, sample survey, statistical analysis and numerical simulation were employed. The distribution patterns of typical vegetation in the basin were determined and the mechanisms underlying the mutual feedbacks between subsurface hydrological process and lakeshore ecosystem was explored. The results show that the Baozhainao lake-basin ecosystem consists of four zoning types, namely, the lake zone, the lake nearshore fluctuation zone, the lakeshore beach zone, and the lakeshore wind beach zone. From the lake to the beach zone, the depth of water table increased gradually and the vegetation type transitions from water-loving and salt-tolerant to drought-tolerant. It was further found that the presence of vegetation on the lake shore significantly affects the circulation mode of the groundwater flow system. The conversion between lake and groundwater occurs mainly in the local groundwater flow system, resulting in a significant reduction in groundwater recharge to the lake.The results of this study can provide a scientific basis for the restoration and conservation of plant species diversity and vegetated ecosystems in the lake nearshore fluctuation zoneand lakeshore wind beach zone in arid regions.

In the sandy land ecosystem with water shortage, soil moisture is the main controlling factor for vegetation restoration and water resources management. Therefore, a correct understanding of the distribution characteristics and spatial-temporal variation of soil moisture in the sandy land is the basis for promoting the sustainable development of sandy land water resources. The Mu Us desert is taken as the study area, in-situ experimental observations, classical statistical analysis and hierarchical clustering analysis methods are used to reveal the spatial and temporal changes of soil profile moisture with or without vegetation cover, and the effect of plant growth on soil water distribution are discussed in this paper. The results show that in the non-freezing period of 2016, when the groundwater depth was relatively shallow, the average soil moisture content increased with the increasing soil depth under the bare land and vegetation coverage. The soil layer of 0−350 cm thick can be divided into the climate-influencing layer, transition layer and groundwater-influencing layer. The average moisture content of the bare soil profile is 23.59%, and the coefficient of variation is 4.25%, which belongs to weak variation. The profile moisture content increased significantly during the observation period, and the rate of increase reached the maximum when the heavy rainfall event occurred in mid-August. The average moisture content of the soil profile under the vegetation cover is 17.74%, and the coefficient of variation is 15.61%, which is a medium variation. The water content of the profile dropped significantly during the observation period, and it dropeds the fastest in August after the Salix matures. At the vertical depth, the influence of vegetation on the soil profile moisture content approximates a Gaussian curve, and has the greatest influence on the moisture content of the transition layer, accounting for more than 50% of the total influence. The impact on climate-influencing layer and groundwater-influencing layer is relatively small. As plants grow, the relative influence on the climate-influencing layer gradually weakens, and the relative influence on the groundwater-influencing layer gradually increases. The research results can provide references for the rational regulation of water resources in the semi-arid Mu Us Sandy Land and the stable development of the sandy land ecosystem.

Groundwater is of important ecological value. The changes in groundwater level, water quality, water content and salt content in the unsaturated zone in groundwater ecosystems drive the evolution of supergene ecological pattern. So far, the research on the ecological threshold of each variable is still at the starting stage, and the theoretical and methodological system is not perfect. In this study the Baoding Plain is taken as an example, and the driving force and ecological effect of groundwater level changes are analyzed from the perspective of time and space by using the historical regression method, GIS method and difference grid calculation method of groundwater levels and groundwater ecological environments. On this basis, the ecological water level thresholds of different hydrogeological units are determined. The results show that: (1) In the 1950s-60s, the ecological pattern of the study area depending on groundwater basically maintained a natural state; from 1959 to 2000, the groundwater levels continued to decline, and the groundwater depression cones appeared in some areas. From 2000 to 2008, the groundwater levels dropped sharply, the groundwater depression cones expanded rapidly, and the recharge and discharge relationship between groundwater and surface water changed. Since 2008, groundwater levels have gradually increased in some regions. (2) The depth of groundwater ecological water level in the piedmont zone of the study area is 10–15 m deep, the Juma River alluvial fan group and Cao River-Pu River alluvial fan group are 5–10 m, the Tang-Dasha River alluvial fan group is 3–5 m, the Dingzhou-Wangdu area in the alluvial plain is 3–5 m, the city of Baoding is about 10–15 m, and the rest are 5–10 m. The area around the alluvial lacustrine plain is less than 3 m. (3) Taking the determined ecological groundwater level as the standard, it is preliminarily estimated that the water demand for restoring the current groundwater level to the ecological water level in the study area is 57.14×108 m3. The research results are of important significance for restoring the local groundwater ecological environment pattern and for determining the ecological groundwater level in the North China Plain.

The research on the mechanism of hydrothermal transfer and transformation and bare soil evaporation is of great significance for water balance and surface energy transformation in surface-groundwater systems. In this paper, based on long-term observations of in situ lysimeter test and numerical simulation, two cases for lysimeter with initial groundwater depths of 80 cm (shallow groundwater depth) and 290 cm (deep groundwater depth) are used to examine the dynamic process of hydrothermal transformation in the variable saturation zone with its effect on bare soil evaporation in the “wind-blown sand area” of the Ordos Basin in China. The results indicate that soil water movement in the variable saturation zone is driven by the head gradient and temperature gradient, showing different movement modes under different groundwater depths. For the situation of shallow groundwater depth, the capillary height can reach the surface, soil water transports upwards with little temperature effects driven by capillary force under the effects of head gradient under the evaporation conditions, and there is no zero flux plane in the soil. When the groundwater depth is less than the capillary height, groundwater directly contributes to soil evaporation driven by capillary force. For the situation of deep groundwater depth, head and temperature are the key factors in the soil water movement, and there is an isolated zero flux plane located at 18 cm below the ground surface, which prevents the upward soil water movement and leads to a decrease in evaporation. When the groundwater depth is greater than 1.6 times the capillary height, groundwater no longer directly involves in soil evaporation, but indirectly affects the water conversion in the unsaturated zone. Therefore, during the simulation period, the cumulative bare soil evaporation of the shallow groundwater depth was about 4 times that of the deep groundwater depth.

Potential evapotranspiration is an essential parameter for regional water balance analysis. To realize the accurate calculation of potential evapotranspiration when data are lacking, scientific evaluation of the applicability of the simplified potential evapotranspiration algorithm in the headwater area of the Yellow River is carried out. Based on daily observation data of temperature, precipitation, relative humidity, wind speed, and sunshine hours from 11 meteorological stations in the headwater area of the Yellow River from 1970 to 2018, the calculation accuracy of six simplified methods for potential evapotranspiration calculation are analyzed by using the FAO Penman-Monteith (PM) method as a reference method from the aspects of the year, month and spatial scales, including the Priestly-Taylor (PT) method, Doorenbos-Pruitt (DP) method, Hargreaves-Samani (HS) method, Rohwer (RO) method, Thornthwaite (TH) method and Blaney-Criddle (BC) method. The results show that the mean deviation between the HS method and the PM method, only 3.487 mm/mon, is the lowest in the headwater area of the Yellow River and the accuracy is the highest. However, the HS method does not consider the influence of the average relative humidity on potential evapotranspiration estimation, resulting in low accuracy in the humid climate of Hongyuan County, Henan County, Ruoergai County, Maqu County and Jiuzhi County in the southeast of the headwater area of the Yellow River. Therefore, this article introduces the average relative humidity factor to modify the HS method and evaluates the application effect of the improved HS method. It is found that after the HS method is revised, the mean deviation of the overall annual potential evapotranspiration in the headwater area of the Yellow River decreases from −22.008 mm/a to 6.174 mm/a, and the mean deviation of the monthly potential evapotranspiration decreases from 3.487 mm/mon to 1.031 mm/mon, respectively. On the spatial scale, the mean deviation of the above 5 counties decreases significantly, with an average drop of 5.33 mm/mon, indicating that the improved HS method can effectively solve the problem of low accuracy in the southeast of the headwater area of the Yellow River, and can provide a reference for the simplified calculation of potential evapotranspiration in the headwater area of the Yellow River.

In regulated rivers, many studies have found that ecological water conveyance was conducive to protection and restoration of riparian plants. However, most of the studies about the influence of water conveyance on plants did not consider river-groundwater relationship in regional scale. In this study, field investigation, dynamic observation, Canonical Correspondence Analysis and ANOSIM analysis were mainly used to explore the lateral zonation of plant composition and diversity among different river-groundwater relationship types and reveal its reasons. The obtained results showed that: Spatio-temporal change of river-groundwater relationship controlled the difference of lateral zonation of species composition and diversity. Within the groundwater fluctuation zone, the water-table depth and salinity decreased during flood season. The proportion of hygrophyte herb and mesophyte shrub species is large with the highest diversity. If the river was gaining river during dry season, the riparian water table depth was less than 4–5 m, the strong evaporation-crystallization process lead to Cl-, Na+, and SO42- enriched. The total dissolved solids (TDS) was more than 6–10 g/L and the plants degenerated to halophyte herbs and shrubs with low diversity outside the groundwater fluctuation zone. If the river dry out during dry season, the riparian water table depth was more than 6–10 m. Plants were under water stress and degenerated to xerophyte herbs and mesophyte and xerophyte shrubs with low diversity outside the groundwater fluctuation zone. The study can enrich the understanding of riparian plant distribution pattern and provide guidance for making appropriate water conveyance scheme.

IntroductionSARS-CoV-2 has ravaged the world and undergone multiple mutations during the course of the COVID-19 pandemic. On 7 April 2022, an epidemic caused by SARS-CoV-2 Omicron (BA.2) variant broke out in Guangzhou, China, one of the largest transportation and logistical hubs of the country.MethodsTo fast curtained the Omicron epidemic, based on the routine surveillance on the risk population of SARS-CoV-2 infection, we identify key places of the epidemic and implement enhanced control measures against Omicron.ResultsTransmission characteristics of the Omicron variant were analyzed for 273 confirmed cases, and key places involved in this epidemic were fully presented. The median incubation time and the generation time were 3 days, and the reproduction number Rt was sharply increased with a peak of 4.20 within 2 days. We tried an all-out effort to tackle the epidemic in key places, and the proportion of confirmed cases increased from 61.17% at Stage 2 to 88.89% at Stage 4. Through delimited risk area management, 99 cases were found, and the cases were isolated in advance for 2.61 ± 2.76 days in a lockdown zone, 0.44 ± 1.08 days in a controlled zone, and 0.27 ± 0.62 days in a precautionary zone. People assigned with yellow code accounted for 30.32% (84/277) of confirmed COVID-19 cases, and 83.33% of them were detected positive over 3 days since code assignment. For the districts outside the epicenter, the implementation duration of NPIs was much shorter compared with the Delta epidemic last year.ConclusionBy blocking out transmission risks and adjusting measures to local epidemic conditions through the all-out effort to tackle the epidemic in key places, by delimiting risk area management, and by conducting health code management of the at-risk population, the Omicron epidemic could be contained quickly.

China implemented stringent non-pharmaceutical interventions (NPIs) in spring 2020, which has effectively suppressed SARS-CoV-2. In this study, we utilized data from routine respiratory virus testing requests from physicians and examined circulation of 11 other respiratory viruses in Southern China, from January 1, 2018 to December 31, 2020. A total of 58,169 throat swabs from patients with acute respiratory tract infections (ARTIs) were collected and tested. We found that while the overall activity of respiratory viruses was lower during the period with stringent NPIs, virus activity rebounded shortly after the NPIs were relaxed and social activities resumed. Only influenza was effectively suppressed with very low circulation which extended to the end of 2020. Circulation of other respiratory viruses in the community was maintained even during the period of stringent interventions, especially for rhinovirus. Our study shows that NPIs against COVID-19 have different impacts on respiratory viruses.

The paper presents different kinds of optimization scheme of air-condition system based on equipment technologies and variable parameters in Guangzhou. Coefficients of performance (COP) and energy efficiency of rate (EER) are the main index of air-condition system. The results show that the percentage of optimized air-condition systems are of different weight ratio based on analytic hierarchy process method. Pump and compressor frequency conversion technologies and higher indoor temperature are the main energy efficiency measurements for air-condition system. The results provide a new methodology for evaluating the air conditioning system construction. [ABSTRACT FROM AUTHOR]

The paper presents the effect of exhaust gas and inlet air temperature on thermal efficiency for boiler system. Based on the numerical model, the performance indexes of boiler system are calculated at different conditions using EES (Engineering Equation Software). The results show that when the exhausted gas or inlet air temperature increases 10-15°C, the heat loss of exhaust gas decreases 0.8%-1% and thermal efficiency of boiler system increases 0.8%-1%; The crucial factors that can affect thermal efficiency are exhaust gas temperature and fuel volatile ratio; seven optimized schemes are designed for a case of boiler system. A new methodology is provided for evaluating the efficiency of boiler system. [ABSTRACT FROM AUTHOR]

Abstract Background Influenza B virus is a main causative pathogen of annual influenza epidemics, however, research on influenza B virus in general lags behind that on influenza A viruses, one of the important reasons is studies on influenza B viruses in animal models are limited. Here we investigated the tree shrew as a potential model for influenza B virus studies. Methods Tree shrews and ferrets were inoculated with either a Yamagata or Victoria lineage influenza B virus. Symptoms including nasal discharge and weight loss were observed. Nasal wash and respiratory tissues were collected at 2, 4 and 6 days post inoculation (DPI). Viral titers were measured in nasal washes and tissues were used for pathological examination and extraction of mRNA for measurement of cytokine expression. Results Clinical signs and pathological changes were also evident in the respiratory tracts of tree shrews and ferrets. Although nasal symptoms including sneezing and rhinorrhea were evident in ferrets infected with influenza B virus, tree shrews showed no significant respiratory symptoms, only milder nasal secretions appeared. Weight loss was observed in tree shrews but not ferrets. V0215 and Y12 replicated in all three animal (ferrets, tree shrews and mice) models with peak titers evident on 2DPI. There were no significant differences in peak viral titers in ferrets and tree shrews inoculated with Y12 at 2 and 4DPI, but viral titers were detected at 6DPI in tree shrews. Tree shrews infected with influenza B virus showed similar seroconversion and respiratory tract pathology to ferrets. Elevated levels of cytokines were detected in the tissues isolated from the respiratory tract after infection with either V0215 or Y12 compared to the levels in the uninfected control in both animals. Overall, the tree shrew was sensitive to infection and disease by influenza B virus. Conclusion The tree shrew to be a promising model for influenza B virus research.