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Wet ponds are a common type of stormwater control measure (SCM) in coastal areas of the southeastern US, but their internal nitrogen dynamics have not been extensively studied. Using flow-through intact sediment core incubations, net sediment N2 fluxes before and after a nitrate addition from five wet ponds spanning a range of ages (3.25-10years old) were quantified through membrane inlet mass spectrometry during early summer. Multiple locations within a single wet pond (6.16years old) were also sampled during ambient conditions in late summer to determine the combined effects of depth, vegetation, and flow path position on net N2 fluxes at the sediment-water interface. All pond sediments had considerable rates of net nitrogen fixation during ambient conditions, and net N2 fluxes during nitrate-enriched conditions were significantly correlated with pond age. Following a nitrate addition to simulate storm conditions, younger pond sediments shifted towards net denitrification, but older ponds exhibited even higher rates of net nitrogen fixation. The pond forebay had significantly higher rates of net nitrogen fixation compared to the main basin, and rates throughout the pond were an order of magnitude higher than the early summer experiment. These results identify less than optimal nitrogen processing in this common SCM, however, data presented here suggest that water column mixing and pond sediment excavation could improve the capacity of wet ponds to enhance water quality by permanently removing nitrogen.

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INTRODUCTION: Kennel facilities are commonly acknowledged as a stressful environment for many domestic dogs (Canis familiaris). One therapeutic measure used to reduce anxiety in dogs is dog appeasing pheromone (DAP), which has been found effective in reducing stress-related behaviours in a number of contexts. AIMS AND OBJECTIVES: A pilot study was conducted to assess whether DAP would reduce frequency of stress-related behaviours in a group of eight dogs housed for teaching purposes in a long-term kennelling facility. MATERIALS AND METHODS: Using video analysis, proportion of time spent in stress-related behaviours for six dogs fitted with DAP collars, versus two control dogs (without collars), was compared for the time before and during DAP exposure. RESULTS: No significant differences were found either in the proportion of time spent in stress-related behaviours in the baseline versus treatment periods or between the collared and control dogs in the change in proportion of time they spent in any of the focal behaviours in the baseline versus treatment periods. CONCLUSIONS: Possible reasons for these findings include an actual lack of effect of DAP on dogs housed in this long-term kennelling facility, an apparent lack of effect due to small sample size in this pilot study and high behavioural variation among individual dogs. Despite lack of a demonstrated effect of the DAP collars on these dogs, attention brought by this study to the behavioural issues seen in some of the dogs did have a positive impact, as it contributed to the development of an active, coordinated behavioural wellness and enrichment programme for the colony.

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Tidal freshwater wetlands in urban settings can be subject to elevated N concentrations, which can promote the exchange of N between the marsh, water, and atmosphere, including denitrification. We used a multitiered approach consisting of direct measurements of N fluxes and denitrification, tidal hypsometry, and N load modeling to examine N exchanges in an urban tidal freshwater wetland of the Delaware River Estuary, Philadelphia, PA. Sediment cores and aboveground biomass were collected at 20 locations across a range of elevations and plant communities in April, July, and October 2010. Nitrate was taken up by the marsh during all seasons. In the spring, the high rate of NH production from the sediment was correlated with NO uptake, suggesting dissimilatory reduction to NH as a potentially important process. Denitrification rates were greatest in July, averaging 5.5 ± 0.6 mg N m h. Adjusted for tidal inundation using a refined digital elevation model, denitrification averaged 0.08, 0.5, and 0.2 g N m mo for April, July, and October, respectively. Less than 10% of the modeled N load was estimated to have been removed in the months measured. A combination of high N load, limited marsh area that represented ∼1% of the watershed area, and conservative extrapolation of denitrification rates contributed to the low estimate of the N load attenuated.

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Diesel fuel pollution in coastal waters, resulting from recreational boating and commercial shipping operations, is common and can adversely affect marine biota. The purpose of this study was to examine the effect of additions of particulate organic carbon (POC) in the form of naturally-occurring marsh grass (Spartina alterniflora), inorganic nutrients (nitrogen and phosphorus), inert particles, and dissolved organic carbon (DOC) on diesel fuel biodegradation and to attempt to formulate an effective bioremedial treatment for small diesel fuel spills in marine waters. Various combinations of treatments were added to water samples from a coastal marina to stimulate diesel fuel biodegradation. Diesel fuel was added in concentrations approximating those found in a spill and biodegradation of straight chain aliphatic constituents was estimated by measuring mineralization of 14C hexadecane added to diesel fuel. All treatments that included POC showed stimulation of biodegradation. However, the addition of inert particles (glass fiber filters and nylon screening) caused no stimulation of biodegradation. The addition of nitrogen and phosphorus alone did not result in stimulation of biodegradation, but nitrogen and Spartina (although not phosphorus and Spartina) did result in stimulation above that of Spartina alone. Maximum biodegradation rates were obtained by the addition of the Spartina POC, ammonium, and phosphate. The addition of mannitol, a labile DOC source with POC and phosphate resulted in a decrease in diesel fuel biodegradation as compared to POC and phosphate alone. The seasonal pattern of diesel fuel biodegradation showed a maximum in the summer and a minimum in the winter. Therefore, of the treatments tested, the most effective for bioremediation of diesel fuel in marine waters is the addition of POC, nitrogen, and phosphorus.

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