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In recent years, the rapid development of industrialization and urbanization has caused serious environmental pollution, especially particulate pollution. As the “Earth’s kidneys,” wetland plays a significant role in improving the environmental quality and adjusting the climate. To study how wetlands work in this aspect, from the early autumn of 2014 to 2015, we implemented a study to measure the PM concentration and chemical composition at three heights (1.5, 6, and 10 m) during different periods (dry, normal water, and wet periods) in the Cuihu wetland park in Beijing for analyzing the dry deposition flux and the effect of meteorological factors on the concentration. Results indicated that (1) the diurnal variations of the PM2.5 and PM10 concentrations at the three heights were similar in that the highest concentration occurred at night and the lowest occurred at noon, and the daytime concentration was lower than that at night; (2) the PM2.5 and PM10 concentrations also varied between different periods that wet period > normal water period > wet period, and the concentration at different heights during different periods varied. In general, the lowest concentration occurred at 10 m during the dry and normal water periods, and the highest concentration occurred at 1.5 m during the wet period. (3) SO42−, NO3−, and Cl− are the dominant constituents of PM2.5, accounting for 42.22, 12.6, and 21.56%, respectively; (4) the dry depositions of PM2.5 and PM10 at 10 m were higher than those at 6 m, and the deposition during the dry period was higher than those during the wet and normal water periods. In addition, the deposition during the night-time was higher than that during the daytime. Moreover, meteorological factors affected the deposition, the temperature and wind speed being negatively correlated with the deposition flux and the humidity being positively correlated. (5) The PM10 and PM2.5 concentrations were influenced by meteorological factors. The PM2.5 and PM10 concentrations were negatively correlated with temperature and wind speed but positively correlated with relative humidity. [ABSTRACT FROM AUTHOR]

• Decomposition rate and effects were measured in field and laboratory experiments. • Measured soil properties and PLFAs for decomposition at different salinities and inundation environments. • Decomposition rate was correlated with water quality and fungal microbe content. • Leaf litter may control carbon cycling and energy flow in estuary ecosystems. • Artificially elevating wetland nutrient content may mitigate negative human impact. Decomposition of halophyte litter may considerably influence carbon cycling and energy flow in estuarine ecosystems. We examined water quality parameters, soil properties, and soil phospholipid fatty acid (PLFA) contents from the Yellow River Estuary, China, to investigate Phragmites australis and Suaeda glauca litter decomposition dynamics. Surface soils (0–10 cm) under three different salinity conditions were collected from six plots. Results showed that the litter decomposition rate of S. glauca (k = 0.0063) was significantly (p = 0.032) higher than that of P. australis (k = 0.0024). Litter decomposition rate had a significant (p < 0.01) relationship with water compositional parameters (water dissolved oxygen, temperature, chemical oxygen demand, and NH 3 -N). According to the results of our surface soil analysis, in plots with 1% salinity, values for total soil PLFAs, bacterial PLFAs, Gram-negative PLFAs, and fungal PLFAs were all higher after 270 days than after 120 days. Fungi were the principal microbial group responsible for leaf litter decay. Changes in the nutrient utilization of litter may result in changes in the allocation of resources for growth and reproduction, which suggests that artificial elevation of wetland nutrient content may mitigate the negative human impacts associated with climate change. This study demonstrated the effects of biotic (litter types, activities of microbial organisms) and abiotic (salinity, inundation) variables on halophyte litter decomposition in Yellow River Delta wetlands. [ABSTRACT FROM AUTHOR]

Atmospheric particulate matter (PM) deposition which involves both dry and wet processes is an important means of controlling air pollution. To investigate the characteristics of dry and wet deposition in wetlands, PM concentrations and meteorological conditions were monitored during summer at heights of 1.5 m, 6 m and 10 m above ground level at Cuihu Wetland (Beijing, China) in order to assess the efficiency of PM2.5 (particles with an aerodynamic size of <2.5 μm) and PM10 (particles with an aerodynamic size of <10 μm) removal. The results showed: Daily concentrations of PM, dry deposition velocities and fluxes changed with the same variation trend. The daily average deposition velocity for PM10 (3.19 ± 1.18 cm·s–1) was almost 10 times that of PM2.5 (0.32 ± 0.33 cm·s–1). For PM2.5, the following dry deposition fluxes were recorded: 10 m (0.170 ± 0.463 μg·m–2·s–1) > 6 m (0.007 ± 0.003 μg·m–2·s–1) > 1.5 m (0.005 ± 0.002 μg·m–2·s–1). And the following deposition fluxes for PM10 were recorded: 10 m (2.163 ± 2.941 μg·m–2·s–1) > 1.5 m (1.565 ± 0.872 μg·m–2·s–1) > 6 m (0.987 ± 0.595 μg·m–2·s–1). In the case of wet deposition, the relative deposition fluxes for PM2.5 and PM10 were 1.5 m > 10 m > 6 m, i.e. there was very little difference between the fluxes for PM2.5 (0.688 ± 0.069 μg·m–2·s–1) and for PM10 (0.904 ± 0.103 μg·m–2·s–1). It was also noted that rainfall intensity and PM diameter influenced wet deposition efficiency. Dry deposition (63%) was more tilted towards removing PM10 than was the case for wet deposition (37%). In terms of PM2.5 removal, wet deposition (92%) was found to be more efficient. [ABSTRACT FROM AUTHOR]

Coastal wetlands, greatly influenced by hydrological processes, are highly productive ecosystems but have suffered serious degradation in many locations. Hydrological connectivity frameworks provide a new perspective to study both hydrological behavior and the relationship between hydrological and ecological processes. Although some indices have been developed to parameterize hydrological connectivity structure (HCS) in different environments, the indices only consider soil water content (SWC) or topography and are limited in some specific areas. Due to its importance to understand ecological-hydrological interaction and wetland conservation and restoration. There is still a necessity to develop indices to capture hydrological attributes. In the current study, we collected soil-hydrological data in the Yellow River Delta and three indices, main flow direction (TM) based on topography, over field capacity index (OFCI) based on SWC, and topographic over field capacity index (TOFCI) based on both topography and SWC are developed using graph theory. The results show OFCI in a semi-artificial pond is significantly higher than in intertidal flats, tidal marshes and riverside wetlands, and TOFCI values in four wetland types differ significantly. TM does not show statistical differences for wetland types explored. According to the parameterized values, the semi-artificial pond has the strongest HCS, followed by intertidal flats. Tidal marshes and riverside wetlands have the weakest HCS. The landscapes of different wetland types are related to the HCS on the surface soil layer, and four wetland types in the Yellow River Delta can be distinguished by TOFCI values. The results also indicate that TOFCI can be used to locate degraded wetland areas for restoration, however more specific relationships between HCS indices and ecological structure are desirable in the future. [ABSTRACT FROM AUTHOR]