Quantifying potential nitrogen removal by denitrification in stream sediments at a regional scale

2004 ◽  
Vol 55 (3) ◽  
pp. 309 ◽  
Author(s):  
M. E. Bartkow ◽  
J. W. Udy
Keyword(s):  
Nitrogen Limitation ◽  
Inorganic Nitrogen ◽  
Regional Scale ◽  
Stream Sediments ◽  
Important Process ◽  
Dissolved Inorganic Nitrogen ◽  
Block Method ◽  
Streams And Rivers ◽  
Nitrogen Loads ◽  
Low Concentrations

Potential denitrification rates were measured using the acetylene block method, in sediments collected from streams in the sub-tropical, south-east Queensland region of Australia. Our aim was to estimate how much nitrogen could be removed from lotic systems by denitrification at the regional scale. Denitrification measured at 65 sites in August and September from a catchment of 22700 km2 was extrapolated to all streams and rivers in the region based on the sediment area available for denitrification. Denitrification rates ranged between 4 and 950 μmol N m–2 h–1, with most sites having rates below 150 μmol N m–2 h–1. Based on these results, the current study estimates that a total of 305 t of nitrogen could be denitrified per year from all streams and rivers in the region, representing 6% of the total annual nitrogen load from surrounding land use. During baseflow conditions, when nitrogen loads to streams are low, the proportion of nitrogen removed through denitrification would be substantially higher, in some cases removing 100% of the nitrogen load. It is proposed that denitrification is an important process maintaining low concentrations of dissolved inorganic nitrogen under baseflow conditions and is therefore likely to enhance nitrogen limitation of primary production in this region.

scholarly journals Catchment land use predicts benthic vegetation in small estuaries

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4378
Author(s):  
Perran L.M. Cook ◽  
Fiona Y. Warry ◽  
Paul Reich ◽  
Ralph Mac Nally ◽  
Ryan J. Woodland
Keyword(s):  
Land Use ◽  
Human Activities ◽  
Inorganic Nitrogen ◽  
Area Ratio ◽  
Nutrient Loads ◽  
Dissolved Inorganic Nitrogen ◽  
Flushing Time ◽  
Nitrogen Loads ◽  
Eastern Australia ◽  
Benthic Vegetation

Many estuaries are becoming increasingly eutrophic from human activities within their catchments. Nutrient loads often are used to assess risk of eutrophication to estuaries, but such data are expensive and time consuming to obtain. We compared the percent of fertilized land within a catchment, dissolved inorganic nitrogen loads, catchment to estuary area ratio and flushing time as predictors of the proportion of macroalgae to total vegetation within 14 estuaries in south-eastern Australia. The percent of fertilized land within the catchment was the best predictor of the proportion of macroalgae within the estuaries studied. There was a transition to a dominance of macroalgae once the proportion of fertilized land in the catchment exceeded 24%, highlighting the sensitivity of estuaries to catchment land use.

Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

2011 ◽  
Vol 347-353 ◽  
pp. 2302-2307 ◽  
Author(s):  
Hong Xiang Wang ◽  
Yi Shi ◽  
Jian Ma ◽  
Cai Yan Lu ◽  
Xin Chen
Keyword(s):  
Point Source ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Inorganic Nitrogen ◽  
Rainfall Amount ◽  
Organic N ◽  
Dissolved Inorganic Nitrogen ◽  
Slope Gradient ◽  
N Loss ◽  
Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

Variation in the instream dissolved inorganic nitrogen response between and within rainstorm events in an urban watershed

2008 ◽  
Vol 43 (11) ◽  
pp. 1223-1233 ◽  
Author(s):  
Bernice R. Rosenzweig ◽  
Hee Sun Moon ◽  
James A. Smith ◽  
Mary Lynn Baeck ◽  
Peter R. Jaffe
Keyword(s):  
Inorganic Nitrogen ◽  
Urban Watershed ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen Response

Modelled estimates of dissolved inorganic nitrogen exported to the Great Barrier Reef lagoon

2021 ◽  
Vol 171 ◽  
pp. 112655
Author(s):  
G.L. McCloskey ◽  
R. Baheerathan ◽  
C. Dougall ◽  
R. Ellis ◽  
F.R. Bennett ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Inorganic Nitrogen ◽  
Barrier Reef ◽  
Dissolved Inorganic Nitrogen ◽  
Reef Lagoon

scholarly journals Effects of Surface Soil Removal on Dynamics of Dissolved Inorganic Nitrogen in a Snow-Dominated Forest

2001 ◽  
Vol 1 ◽  
pp. 527-533 ◽  
Author(s):  
M. Ozawa ◽  
H. Shibata ◽  
F. Satoh ◽  
K. Sasa
Keyword(s):  
Soil Solution ◽  
Soil Removal ◽  
Surface Soil ◽  
Water Movement ◽  
Inorganic Nitrogen ◽  
Seasonal Fluctuation ◽  
Early Spring ◽  
Dissolved Inorganic Nitrogen ◽  
And Control ◽  
Treated Site

To clarify the effect of vegetation and surface soil removal on dissolved inorganic nitrogen (N) dynamics in a snow-dominated forest soil in northern Japan, the seasonal fluctuation of N concentrations in soil solution and the annual flux of N in soil were investigated at a treated site (in which surface soil, including understory vegetation and organic and A horizons, was removed) and control sites from July 1998 to June 2000. Nitrate (NO3–) concentration in soil solution at the treated site was significantly higher than that of the control in the no-snow period, and it was decreased by dilution from melting snow. The annual net outputs of NO3–from soil at the treated site and control sites were 257 and –12 mmol m–2year–1, and about 57% of the net output at the treated site occurred during the snowmelt period. NO3–was transported from the upper level to the lower level of soil via water movement during late autumn and winter, and it was retained in soil and leached by melt water in early spring. Removing vegetation and surface soil resulted in an increase in NO3–concentration of soil solution, and snowmelt strongly affected the NO3–leaching from treated soil and the NO3–restoration process in a snow-dominated region.

scholarly journals Forest defoliator outbreaks alter nutrient cycling in northern waters

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Samuel G. Woodman ◽  
Sacha Khoury ◽  
Ronald E. Fournier ◽  
Erik J. S. Emilson ◽  
John M. Gunn ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Chemistry ◽  
Inorganic Nitrogen ◽  
Biogeochemical Cycles ◽  
Dissolved Inorganic Nitrogen ◽  
Insect Outbreaks ◽  
Receiving Waters ◽  
North Temperate Lakes ◽  
Lake Waters ◽  
Terrestrial Biomass

AbstractInsect defoliators alter biogeochemical cycles from land into receiving waters by consuming terrestrial biomass and releasing biolabile frass. Here, we related insect outbreaks to water chemistry across 12 boreal lake catchments over 32-years. We report, on average, 27% lower dissolved organic carbon (DOC) and 112% higher dissolved inorganic nitrogen (DIN) concentrations in lake waters when defoliators covered entire catchments and reduced leaf area. DOC reductions reached 32% when deciduous stands dominated. Within-year changes in DOC from insect outbreaks exceeded 86% of between-year trends across a larger dataset of 266 boreal and north temperate lakes from 1990 to 2016. Similarly, within-year increases in DIN from insect outbreaks exceeded local, between-year changes in DIN by 12-times, on average. As insect defoliator outbreaks occur at least every 5 years across a wider 439,661 km2 boreal ecozone of Ontario, we suggest they are an underappreciated driver of biogeochemical cycles in forest catchments of this region.

Dissolved Inorganic Nitrogen Fluxes at Sediment-Water Interface in Yangtze Estuarine Tidal Flat

2013 ◽  
Vol 726-731 ◽  
pp. 288-295 ◽  
Author(s):  
Huan Guang Deng ◽  
Dong Qi Wang ◽  
Zhen Lou Chen
Keyword(s):  
Tidal Flat ◽  
Environmental Gradients ◽  
Inorganic Nitrogen ◽  
Yangtze Estuary ◽  
Water Interface ◽  
Dissolved Inorganic Nitrogen ◽  
Overlying Water ◽  
Spatial Differences ◽  
Estuary Sediment ◽  
Temporal And Spatial

Yangtze estuary data, collected over three years, indicates that the temporal and spatial distributions of the environmental gradients reflect complicated seasonal changes and spatial differences in the exchange flux of the dissolved inorganic nitrogen (DIN= NH4++ NO3-+ NO2-) across the sediment-water interface. Overall in northern sites of Yangtze estuary, sediment was a source of ammonium (NH4+) (-3.67~10.65 mmol·m-2·d-1) probably because of higher salinities. Sediment was a sink for NH4+ in southern sites (-18.45~3.33 mmol·m-2·d-1) during most years. The exchange behavior of nitrate (NO3-) showed temporal and spatial variation from the upper to lower estuary and ranged from-32.8 mmol·m-2·d-1 to 35.8 mmol·m-2·d-1. The interface exchange direction of ammonium was affected by NH4+ concentration, but the relationship between NO3- concentration and the direction of flux was not obvious. The concentration of nitrite (NO2-) was very low and its interface flux was not related to DIN concentration. Overall, the sediment of Yangtze Estuarine tidal flat was a source of DIN to overlying water in the spring, but a sink for DIN during the other three seasons of the year.

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