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River–riparian interface (RRI) plays a crucial role in nitrogen removal and N2O emissions, but different revetment constructions can significantly alter the associated outcomes. Identifying which type of revetment can reduce N2O emissions while still removing nitrogen is a key issue in urban development. This study constructed three types of revetments along the same river section, and measured soil, vegetation, microbial, denitrification, and N2O emission characteristics to explore the synergistic effects of revetment types on nitrogen removal and N2O emissions. The study showed that revetments affected nitrogen removal and N2O emissions in RRI by influencing denitrification. nirK mainly affected nitrogen removal, while nosZII mainly influenced N2O emissions. Environmental factors in the permeable revetment led to significantly higher gene abundances of nirK and nosZII compared to those in the natural and impermeable revetments. As a result, the denitrification potential of the permeable revetment (34.32 ± 1.17 mg/(kg·d)) was 22.43% and 8.84% higher than those of the natural and impermeable revetments, respectively. The N2O emission rate (0.35 ± 0.01 mg/(m2·h)) was 29.22% and 22.19% lower than those of the natural and impermeable revetments, respectively. Permeable revetment could have been the best for the nitrogen removal and N2O emission reduction. These results provide a theoretical basis and guidance for urban ecological construction. [ABSTRACT FROM AUTHOR]

River-riparian interfaces (RRIs) of urban rivers are where river ecosystems interact with the riparian soil ecosystems. However, with the intensification of urbanization, the construction of various revetments changes the energy exchange process between the river and the RRI, affects the soil properties, and then affects the soil bacterial community composition and structure. In this study, natural (NR), permeable (PR), and impervious revetments (IR) of the same river section were selected. The composition and abundance of soil bacterial communities were detected by PCR amplification technology. The Alpha diversity, Beta diversity, community composition, and environmental factor correlations of bacterial communities were analyzed. The results showed: (1) The dominant bacterial genera of NR, IR, and PR were similar, mainly Anaerolineae, Vicinamibacterales, Ardenticatenales, and Rokubacteriales. There were 504 bacterial genera with the same NR, IR, and PR, accounting for NR, IR, and PR bacterial genera 69.52%, 69.33%, and 62.22% of the total, respectively. (2) Due to the material and energy exchange between soil water and river water and the buffering effect of permeable revetment on frequent river water level changes, the bacterial community richness, community diversity, and lineage diversity of PR are higher than those of NR and IR. (3) SOM, pH, oxygen, and soil nutrients are critical environmental factors that affect the composition and abundance of soil bacterial communities at RRI. The research results provide a theoretical basis for further exploring the impact of urban river revetment on the service function of soil ecosystems at RRI.

The freezing and thawing process is a unique feature of the alpine permafrost ecosystem, which controls the growth of microorganisms and alpine meadows, and plays a vital role in animal husbandry development, ecosystem functions and services. Meanwhile, the freezing and thawing process is also affected by external environmental factors, and its spatial differences are very significant, especially in the regions over 5000 m a.s.l. In this study, the freezing and thawing process periods of the Cuoma Township (CM), Xiangmao Township (XM) and Xiaotanggula Mountain (XTGL) sites in the Nagqu River Basin are divided, the effects of altitude, vegetation coverage, air temperature, and organic matter content on the freezing and thawing process are analyzed, the main influencing factors are discussed. The results show that in the regions over 5000 m a.s.l, the thaw initiation period (TIP) starts in early April, the entirely thawed period (ETP) starts in end of May, the freeze initiation period (FIP) starts in end of October, and the entirely frozen period (EFP) starts in early November. Compared with the regions below 5000 m a.s.l, FIP and EFP in the regions over 5000 m a.s.l start earlier, the TIP starts later and the freezing rate is faster. Organic matter content is the main influencing factor during FIP and EFP, and air temperature is the main influencing factor during TIP and ETP. This study is helpful to clarify the changes of freezing and thawing process in the regions over 5000 m a.s.l, and also provides theoretical support for ecological protection and restoration.

Urban green and blue space (GBS) significantly impacts the diffusion range of atmospheric particulate matter. By determining the diffusion distance of atmospheric particulate matter (PM2.5 and PM10) in Shanghai, combined with the GBS landscape pattern index, this study completed a stepwise multiple regression equation and correlation analysis to explore the relationship between the morphological structure and spatial configuration of GBS on the diffusion distance of atmospheric particles. The results show that the landscape shape index (LSI) and the number of patches (NP) of GBS have a significant positive correlation with the diffusion distance of atmospheric particles, while the coefficient of the percent of landscape (PLAND), as a key influencing factor, has a negative correlation. The mean Euclidean nearest neighbor distance (ENN_MN) and splitting index (SPLIT) in the spatial configuration metrics positively affect the diffusion distance. Studies have proved that complex and dispersed GBS will lead to the weakening of its purification ability, thereby increasing the pollution range of atmospheric particulate matter. The order of the influence of different GBS types on the diffusion distance of atmospheric particles is as follows: DT > BS > LP > ST > WA. Therefore, high-density GBS with simple shapes and concentrated distribution should be considered in the future construction of new cities. [ABSTRACT FROM AUTHOR]

Observing and analyzing runoff process is an important method to study the principle of runoff yield and concentration. However, natural rainfall is random and difficult to monitor the related runoff process timely, so most of the runoff processes analysis is based on the artificial rainfall experiments. In this study, the selected test site is located in Yongnian district, Hebei Province, China. Rainfall volume, rainfall peak, rainfall duration and peak ratio were considered as the key factors of designed rainfall type. Based on regional historical observed rainfall data from 1980 to 2012, the two mainly representative processes which was in flood season and non-flood season respectively, were calculated. The most typical rainfall process in each period was screened through two methods of characteristic frequency distribution. Furthermore, accuracy of rainfall intensity and uniformity of spatial and temporal distribution were selected as the criteria for correcting the artificial rainfall devices. This research is the foundation of the artificial runoff experiment and provide reference to regional climate change research and local water resources assessment.

In order to implement the reform of the water resources fee in Hebei Province, the right confirmation of water resources use is crucial. In this study, Yangyuan County of Zhangjiakou, Hebei Province was selected for the research and the regional situations of hydrology, social economy, water conservancy project distribution and water supply were analyzed. Then, rights of residential water use, industrial water use, ecological water use, reserve water amount and agricultural water use in study region were calculated. Furthermore, the corresponding scheme of water use rights was confirmed. The results could provide technical support to the optimization of water resources management for Yangyuan County and reference to other regions of Hebei Province.

Particulate matter (PM) in urban riparian green spaces are undesirable for human participation in outdoor activities, especially PM2.5 and PM10. The PM deposition, dispersion and modification are influenced by various factors including vegetation, water bodies and meteorological conditions. This study aimed to investigate the impact of vegetation structures and the river's presence on PM in riparian zones. The spatial-temporal variations of PM2.5 and PM10 concentrations in three riparian vegetation communities with different structures (open grassland (G), arbor-grass (AG) and arbor-shrub-grass (ASG) woodlands) were monitored under relatively stable environment. The removal percentages (RP) and ratios of PM2.5 and PM10 were calculated and compared to identify the removal effect of vegetation structures and the river's presence. It is found that: (1) when the wind was static (hourly wind speed < 0.2 m/s), the RP was ranked as follows: G > AG > ASG. When the wind was mild (0.2 m/s < hourly wind speed < 2 m/s), the RP was ranked as follows: G > ASG > AG. Generally, the G had the best removal effect during the monitoring period; (2) the lowest RP occurred in the middle of the G (–3.4% for PM2.5, 1.8% for PM10) while the highest RP were found in middle of the AG and ASG, respectively (AG: 2.1% for PM2.5, 6.7% for PM10; ASG: 2.4% for PM2.5, 6.3% for PM10). Vegetation cover changed the way of natural deposition and dispersion; (3) compared with static periods, PM removal percentages were significantly reduced under mild wind conditions, and they were positively correlated with wind speed during the mild-wind period. Thus, a piecewise function was inferred between wind speed and PM removal percentage; (4) for all three communities, the 1 m-to-river PM2.5/PM10 ratio was significantly lower than that at 6 m and 11 m, even lower than that in the ambient atmosphere. The river likely promoted the hygroscopic growth of PM2.5 and the generation of larger-sized particles by coagulation effect. Based on these findings, open grassland space is preferred alongside rivers and space for outdoor activities is suggested under canopies in the middle of woodlands. [ABSTRACT FROM AUTHOR]