In this study we used the phytoremediation techniques to treatment diesel contaminated wetland soil. At first, we compared the four common wetland plants, Typha orientalis Presl, Cyperus malaccensis, Bolbos choenus planieulmis and Phragmites communis, on the treatment efficiency of the diesel contaminated wetland soils. From the results, we find out that the Typha orientalis Presl has highest growth rate and activity on rhizosphere among the four species. The Typha orientalis Presl was planted on artifical diesel contaminated wetland soil and incubated inside a greenhouse, while a control system without vegetation is compared. After 240 days, the result shows that soil planted with Typha orientalis Presl can enhance the microbial and dehydrogenase activity. And adding with nutrients can help plants to prevent the diesel stress. Finally, we utilized the PCR/DGGE methods to analyze soil microbial diversity. According to the DGGE profiles, presence of Typha orientalis Presl can augment microbial diversity . So far as degradation of TPH-d to be concerned, because of the period was too short, it doesn¡¦t have significant difference between treatments. However, presence of Typha orientalis Presl and addition of nutrients, the TPH-D degradation rate was measured to be approximately 80 % and concentration of TPH-D could degrade from 16000 mg kg-1 to 3500 mg kg-1 after 240 days.

Loss of wetland habitats across the nation is staggering and continues, especially in urbanizing areas. Thus, wetland restoration has become a priority. However, questions remain regarding system function and biotic communities. We studied a constructed floodplain wetland complex near Dallas, Texas. We sought to improve understanding of wetland ecosystem development under the influence of different approaches to wetland restoration in an urbanizing landscape. In the wetland complex, 10 constructed sloughs, approximately 70m by 15m, were designated for this study. Our experiment monitored the establishment of aquatic plant and invertebrate communities under different experimental conditions. In 5 sloughs, 5 native perennial hydrophyte species were transplanted in blocks in each slough, with the remaining 5 sloughs unplanted. Portions of each slough were caged to determine the effects of protective caging. Using 1m2 caged and neighboring uncaged areas as quadrats, we sampled vegetation and the invertebrate community over two years to determine the effects of restoration treatmentsSlough planting did not result in statistically different levels of plant cover. However, invertebrate abundance was greater in planted sloughs, and plant composition was different, comprised more of perennial species in planted sloughs than in unplanted sloughs. Caging did not have an effect on plant or invertebrate communities. However, changes due to time resulted in significant increases in plant cover and invertebrate abundance and shifts in community composition. Four of 5 transplanted species were emergent growth forms. Emergent cover and the remaining species, Potamogeton nodosus, a floating-leafed plant, accounted for invertebrate community variation. Transplanted emergent species did not fare well, though other emergent species did colonize the site, along with widespread coverage by submerged Najas guadalupensis. Potamogeton spread rapidly, colonizing unplanted sloughs, and this will likely affect community development across the site. Plant and invertebrate richness values were low, likely due to hydrological extremes and the short period of time since construction. Water level fluctuations resulted in plant communities dominated by obligate wetland plants, though drought stress took a toll on survival of plants and invertebrates in late summer. Community development and system function were dependent mostly upon time and hydrology. on the communities.

<p dir="ltr">Excess nitrogen loading to surface waters and groundwater from intensive agriculture threatens human and ecosystem health and economic prosperity within and downstream of the Mississippi River Basin. Restoring wetlands and floodplains reduces nitrogen export, but nitrogen export from the Mississippi River Basin remains elevated. Engineering restored wetlands and floodplains to have higher areal denitrification rates is necessary to advance toward nitrogen reduction goals. Environmental controls of denitrification in restored ecosystems must be further investigated to determine under what conditions denitrification is highest and to link these optimal conditions to restoration approaches. Yet, restoration efforts to reduce nitrogen export may inadvertently increase phosphorus export and greenhouse gas emissions. We evaluated different restoration design approaches and identified environmental controls of denitrification, phosphorus release, and greenhouse gas production to advance knowledge of how floodplain and wetland restorations can be designed and managed to maximize denitrification while also constraining phosphorus release and greenhouse gas production. Comparisons of different restoration design approaches in the Wabash River Basin in Indiana, U.S.A., demonstrated that a hydrologically connected floodplain with row crop agriculture provides limited N treatment. Floodplain restorations that involved structural modifications to enhance hydrologic connectivity supported higher denitrification than restorations that only reestablished native vegetation. Investigations of the plot- and field-scale drivers of denitrification indicated that enhanced hydrologic connectivity and specific native wetland and prairie vegetation types were associated with soil conditions that supported high denitrification potential, mainly sufficient soil moisture and bioavailable organic matter. These same soil conditions were associated with increased risks of phosphorus release and greenhouse gas production. However, artificial flooding experiments showed that preventing prolonged flooding has a strong potential to reduce phosphorus export from floodplains with limited impacts on nitrogen treatment. Microcosm experiments with plant litter and wetland soils indicated that certain wetland vegetation types may reduce greenhouse gas production without sacrificing nitrogen removal capacity based on differences in plant biomass composition.</p>

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The National Wetlands Inventory (NWI) is the definitive source for wetland resources in the United States. The NWI production unit in Hadley, MA has begun to upgrade their digital map database, integrating descriptors for assessment of wetland functions. Updating is conducted manually and some automation is needed to increase production and efficiency. This study assigned landscape position descriptor codes to NWI wetland polygons and correlated polygon environmental properties with public domain terrain, soils, hydrology, and vegetation data within the Coastal Plain of Virginia. Environmental properties were applied to a non-metric multidimensional scaling technique to identify similarities within individual landscape positions based on wetland plant indicators, primary and secondary hydrology indicators, and field indicators of hydric soils. Individual NWI landscape position classes were linked to field-validated environmental properties. Measures provided by this analysis indicated that wetland plant occurrence and wetland plant status obtained a stress value of 0.136 (Kruskal's stress measure = poor), which is a poor indicator when determining correlation among wetland environmental properties. This is due principally to the highly-variable plant distribution and wetland plant status found among the field-validated sites. Primary and secondary hydrology indicators obtained a stress rating of 0.097 (Kruskal's stress measure = good) for correlation. The hydrology indicators measured in this analysis had a high level of correlation with all NWI landscape position classes due the common occurrence of at least one primary hydrology indicator in all field validated wetlands. The secondary indicators had an increased accuracy in landscape position discrimination over the primary indicators because they were less ubiquitous. Hydric soil characteristics listed in the 1987 Manual and NTCHS field indicators of hydric soils proved to be a relatively poor indicator, based on Kruskal's stress measure of 0.117, for contrasting landscape position classes because the same values occurred across all classes. The six NWI field–validated landscape position classes used in this study were then further applied in a public domain digital data analysis. Mean pixel attribute values extracted from the 180 field-validated wetlands were analyzed using cluster analysis. The percent hydric soil component displayed the greatest variance when compared to elevation and slope curvature, streamflow and waterbody, Cowardin classification, and wetland vegetation type. Limitations of the soil survey data included: variable date of acquisition, small scale compared to wetland size, and variable quality. Flow had limitations related to its linear attributes, therefore is often found insignificant when evaluating pixel values that are mean of selected pixels across of wetland landscape position polygons. NLCD data limitations included poor quality resolution (large pixel size) and variable classification of cover types. The three sources of information that would improve wetland mapping and modeling the subtle changes in elevation and slope curvature that characterize wetland landscapes are: recent high resolution leaf-off aerial photography, high-quality soil survey data, and high-resolution elevation data. Due to the data limitations and the choice of variables used in this study, development of models and rules that clearly separate the six different landscape positions was not possible, and thus automation of coding could not be attempted. / Master of Science