Spatial Changes in Microbial Communities along Different Functional Zones of a Free-Water Surface Wetland

Constructed wetlands (CWs) are complicated ecosystems that include vegetation, sediments, and the associated microbiome mediating numerous processes in wastewater treatment. CWs have various functional zones where contrasting biochemical processes occur. Since these zones are characterized by different particle-size composition, physicochemical conditions, and vegetation, one can expect the presence of distinct microbiomes across different CW zones. Here, we investigated spatial changes in microbiomes along different functional zones of a free-water surface wetland located in Moscow, Russia. The microbiome structure was analyzed using Illumina MiSeq amplicon sequencing. We also determined particle diameter and surface area of sediments, as well as chemical composition of organic pollutants in different CW zones. Specific organic particle aggregates similar to activated sludge flocs were identified in the sediments. The highest accumulation of hydrocarbons was found in the zones with predominant sedimentation of fine fractions. Phytofilters had the highest rate of organic pollutants decomposition and predominance of Smithella, Ignavibacterium, and Methanothrix. The sedimentation tank had lower microbial diversity, and higher relative abundances of Parcubacteria, Proteiniclasticum, and Macellibacteroides, as well as higher predicted abundances of genes related to methanogenesis and methanotrophy. Thus, spatial changes in microbiomes of constructed wetlands can be associated with different types of wastewater treatment processes.

Study on Purification Effect of Artificial Wetland on Micro-polluted River

The research on the purification effect of artificial wetland on micro-polluted river and the detection of aquatic plants showed that TP, TN, NH3-N and COD in river were significantly lower than those in untreated river, indicating that the artificial wetland has a good purification effect on these water quality indicators; Testing from different wetland types, it can be seen that the effect of removing TP, TN, NH3-N and other factors in the subsurface wetland is the best, and the artificial surface wetland is second, while the effect of removing COD factor it is close to that of artificial surface wetland. As for the effect of removing pollution factors in artificial wetlands in different seasons, it can be drawn frow the test that the removal rate of TP and TN in artificial wetlands in different seasons can be obtained: wet season > normal season > dry season; and the removal rate of NH3-N and COD is normal season > dry season > wet season. In addition to the TN factor, the water quality during the dry season and normal season is significantly better than that during the wet season. Based on the analysis of the total amount of heavy metals absorbed by three kinds of aquatic plants, it can be concluded that different plant has different effect of removing TN and TP.

Extent, regional distribution and changes in area of different classes of wetland

We compiled available data and information on the global and regional areas (Ramsar regions), and changes in area, of 22 classes of marine or coastal and inland wetlands. From those classes for which there is information, inland natural surface wetlands (forming ~77% of total surface wetland extent) are dominated by non-forested peatlands, marshes and swamps on alluvial soils, with peatlands forming ~33% of natural inland wetlands. The smaller area of marine or coastal wetlands (~10% of total wetland extent) is dominated by unvegetated tidal flats and saltmarshes. Largest areas of human-made wetlands for which there is information are rice paddy and water storage bodies, with a much smaller area of tropical oil palm and pulpwood plantations. These human-made wetlands are all increasing in area. The reported decline in global natural wetland area is occurring across almost all classes of inland and marine or coastal natural wetlands. Total global wetland area estimated from these wetland classes is between 15.2×106 and 16.2×106km2, similar to recent global wetland area estimates derived from remote sensing. Given the considerable data gaps for area of wetland classes, even the most recent other estimates of global wetland extent are likely to be underestimates.

An investigation into the relationship between water quality volume (design storage volume) and stormwater wetland performance

An investigation on free water surface wetland, which has an area of 0.23 ha and is employed to control the non-point source pollution from a watershed of 7.4 ha, was carried out to examine how the WQvr (the ratio of stormwater inflow volume to water quality volume (WQv)) affects the wetland treatment performance. As stormwater went through the wetland, TSS (total suspended solids), TCOD (total chemical oxygen demand), TN (total nitrogen) and TP (total phosphorus) were reduced by 85%, 57%, 6% and 68%, on average, respectively. Increase in the WQvr resulted in a decrease in the reduction efficiencies of TSS, TCOD and TP, but a slight increase in TN removal. WQv was identified as a useful parameter for the design of stormwater wetlands, as this volumetric design approach overcomes the variation in flow rate and pollutant concentrations with respect to time and rainfall conditions. However, the design goal of 80% TSS reduction was not accomplished as inflow water volume equal to designed WQv. On the other hand, it was found that TCOD and TP reduction could also be considered as wetland design goals together with TSS. However, TN reduction did not show any significant relationship with the WQv.