Relative contribution of multi-source water recharge to riparian wetlands along the lower Yellow River.

Rivers play a vital role in both the formation and maintenance of riparian wetland hydrology. However, few studies have focused on the response of water recharge of riparian wetlands to altered hydrological processes induced by water-sediment regulation practices. To fill this gap, our study investigated the contribution of multi-source water recharge of riparian wetlands in the lower Yellow River, as well as its influence both during and before the water-sediment regulation scheme of Xiaolangdi Dam. Our study is based on hydrochemistry and isotopic methods, using a Bayesian mixing model and artificial neutral network model. The results showed that riparian wetlands were fed by mixed sources, including groundwater, canals, the Yellow River, and precipitation. However, seasonal evaporation introduced additional variation, which affected the relative contribution of these sources across seasons. Among these sources, the Yellow River served as the main water source for recharging riparian wetlands, and its contribution varied both spatially and temporally (across seasons). Specifically, proximity of riparian wetlands was the primary factor explaining spatial variation in the contribution of Yellow River, while climatic (12.38%) and hydrological variabilities (87.62%) explained seasonal variation. Among these climatic and hydrological variables, suspended sediment content was the most important factor-with a relative contribution of 36.33%. By determining the contribution of the Yellow River to the recharge of riparian wetlands, our study has provided information which is beneficial to adaptive management of river-fed riparian wetlands, especially under the implementation of water-sediment regulation practices.

Fast particles overtaking shock front in two-dimensional Yukawa solids.

High-speed particles overtaking the shock front during the propagation of compressional shocks in two-dimensional (2D) Yukawa solids are investigated using molecular dynamical simulations. When the compressional speed is lower, all particles around the shock front are almost accelerated synchronously. However, when the compressional speed is much higher, some particles penetrate the shock front to enter the preshock region. Around the shock front, it is found that the particle velocity profile at the first peak of the dispersive shock wave (DSW) is able to be described using the Gaussian distribution, so that the amplitudes of the DSW can be well characterized. As the compressional speed increases, the particle velocity corresponding to these DSW's amplitudes increase more substantially than the shock front speed. These amplitudes of the DSW are found to be able to predict the occurrence of the fast particles. Combined with the previous study of the DSW's period, it is demonstrated that the properties of the DSW are nearly not affected by the conditions of the 2D Yukawa systems, but only related to the compressional speed.

Effects of microhabitat characteristics on amphibian diversity in urban water system of Kaifeng, Henan, China.

Amphibians with a unique life history are extremely sensitive to environmental changes. They are important indicator species for environmental change. The construction of Kaifeng water system affects the habitat and biodiversity of amphibians. In this study, we investigated the amphi-bians in water system of Kaifeng by setting sample points and using visual encounter method, and measured the habitat variables. We quantified amphibian biodiversity under different habitat types using the Shannon diversity index, Pielou evenness index and Simpson dominance index, and explored the responses of amphibians to microhabitat variations by cluster analysis and redundancy analysis. The results showed that the diversity, evenness, and dominance of amphibians in the natural revetment were higher than those in the artificial hardened revetment, indicating a more stable amphibian population in the natural habitat. The dominance index of amphibians on natural revetment was higher than that of the two artificially hardened revetments, indicating that amphibians preferred natural habitat. The abundance of both Palophylax nigromaculata and Bufo gargarizans had significant positive correlation with night light intensity, while the abundance of P. plancyi was positively correlated with total phosphorus, and that of Fejervarya limnocharis was positively correlated with water pH. The protection of amphibians should be considered in the construction of urban water system in Kaifeng. The presence of more natural revetment would be of great significance to enhance amphibian biodiversity.

Plant trait-environment trends and their conservation implications for riparian wetlands in the Yellow River.

Determining the relationship between plant functional traits and the environment are key for the protection and sustainable utilization of riparian wetlands. In the middle and lower reaches of the Yellow River, riparian wetlands are divided into seasonal floodplain wetlands (natural) and pond-like wetlands or paddy fields (artificial). Here, species composition differences were catalogued based on plant functional traits including origin, life history, and wetland affinity in natural and artificial wetlands. Wetland physicochemical characteristics and regional socio-economic parameters collected as indicators of environmental variables were used to analyze the plant functional trait-environment relationship. The results reveal that plant functional traits in the seasonal floodplain wetland are impacted by physicochemical characteristics of habitat. The abundance of annual plants tends to decrease with concentration of heavy metals, while species diversity is mainly determined by soil physical and chemical properties, especially soil pH and temperature. Specifically, wetland-obligate species (not in water) are more resistant to heavy metal content in water than species with other types of wetland affinity. Life history strategies of species in artificial sites tend to be significantly associated with animal husbandry and artificial populations, while the wetland affinity of species is mainly determined by regional agriculture, especially the installation of agricultural covered areas. Furthermore, water quality and nutrients in suspended sediments from the Yellow River affected species diversity and life history strategies by affecting water and soil conditions of surrounding wetlands, especially conductivity and phosphorus levels.