scholarly journals High-Frequency Monitoring Reveals Multiple Frequencies of Nitrogen and Carbon Mass Balance Dynamics in a Headwater Stream

2021 ◽  
Vol 3 ◽  
Author(s):  
Kieran Khamis ◽  
Phillip J. Blaen ◽  
Sophie Comer-Warner ◽  
David M. Hannah ◽  
A. Rob MacKenzie ◽  
...  
Keyword(s):  
Mass Balance ◽  
Nutrient Uptake ◽  
Nitrate Uptake ◽  
Agricultural Activity ◽  
Storm Events ◽  
Short Term ◽  
Catchment Scale ◽  
Uptake Rates ◽  
Nutrient Mass Balance ◽  
Multiple Frequencies

The uptake of aquatic nutrients can represent a major pathway for their removal from river ecosystems and is a key control on nitrogen and carbon export from watersheds. Our understanding of temporal variability in nutrient mass balance is incomplete as conventional methods for estimating uptake rates are suited to low-frequency analysis. Here, we utilised hourly streamflow, nitrate (NO3--N) and dissolved organic carbon (DOC) to generate near-continuous estimates of nutrient uptake along a 1 km reach in a headwater catchment with a history of agricultural activity. We identified variability in nutrient mass balance at multiple frequencies. Over seasonal timescales, a shift from nitrate release during spring to uptake during autumn was apparent. In contrast, consistent uptake of DOC was observed across the whole monitoring period (i.e., spring—autumn). Both DOC and nitrate uptake were related significantly to environmental variables (river discharge) and antecedent discharge conditions. DOC:nitrate stoichiometry appeared to be a key control on nitrate uptake rates, yet this coupling weakened from summer to autumn as DOC became more abundant and physical controls become more important. Daily cycles in nutrient uptake were evident and at times the investigated reach acted as a net sink of DOC during the day and a source at night. Short-term impacts of storm events on uptake rates varied seasonally but no consistent changes were observed between pre- and post-event conditions, suggesting aquatic communities were resilient to short-term flow disturbances. For the duration of our study, the reach acted as net sink from the water for DOC (−1.7% of upstream flux) and a net source for nitrate (+2.6%). Even during autumn, when uptake was greatest, mass removal represented <3% of nitrate exported downstream. Our results facilitate new insights into multi-timescale patterns and drivers of stream ecosystem processes, which are essential for developing effective catchment-scale management strategies.

Measurement of short-term nutrient uptake rates in cranberry by aeroponics

1996 ◽  
Vol 19 (2) ◽  
pp. 237-242 ◽  
Author(s):  
P. BARAK ◽  
J. D. SMITH ◽  
A. R. KRUEGER ◽  
L. A. PETERSON
Keyword(s):  
Nutrient Uptake ◽  
Short Term ◽  
Uptake Rates

scholarly journals Technical Note: A comparison of two empirical approaches to estimate in-stream net nutrient uptake

2011 ◽  
Vol 8 (4) ◽  
pp. 875-882 ◽  
Author(s):  
D. von Schiller ◽  
S. Bernal ◽  
E. Martí
Keyword(s):  
Mass Balance ◽  
Nutrient Uptake ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Data Set ◽  
Advantages And Disadvantages ◽  
Balance Approach ◽  
Uptake Rates ◽  
Empirical Approaches ◽  
Mass Balance Approach

Abstract. To establish the relevance of in-stream processes on nutrient export at catchment scale it is important to accurately estimate whole-reach net nutrient uptake rates that consider both uptake and release processes. Two empirical approaches have been used in the literature to estimate these rates: (a) the mass balance approach, which considers changes in ambient nutrient loads corrected by groundwater inputs between two stream locations separated by a certain distance, and (b) the spiralling approach, which is based on the patterns of longitudinal variation in ambient nutrient concentrations along a reach following the nutrient spiralling concept. In this study, we compared the estimates of in-stream net nutrient uptake rates of nitrate (NO3) and ammonium (NH4) and the associated uncertainty obtained with these two approaches at different ambient conditions using a data set of monthly samplings in two contrasting stream reaches during two hydrological years. Overall, the rates calculated with the mass balance approach tended to be higher than those calculated with the spiralling approach only at high ambient nitrogen (N) concentrations. Uncertainty associated with these estimates also differed between both approaches, especially for NH4 due to the general lack of significant longitudinal patterns in concentration. The advantages and disadvantages of each of the approaches are discussed.

Ammonia and Nitrate Uptake in the Lower Great Lakes

1980 ◽  
Vol 37 (9) ◽  
pp. 1365-1372 ◽  
Author(s):  
T. P. Murphy
Keyword(s):  
Great Lakes ◽  
Nitrate Uptake ◽  
Nutrient Concentrations ◽  
Short Term ◽  
Low Concentrations ◽  
Uptake Rates ◽  
Low K ◽  
Slow Turnover

Uptake of NH4+ is consistent with Michaelis–Menten kinetics in the Lower Great Lakes only if one assumes that the indophenol method of measuring NH4+ overestimates the in situ concentration. Short-term incubations were found necessary to avoid induction of nitrate uptake or changes in the rates of NH4+ uptake that occurred in long-term incubations. Uptake rates of nitrate are slow most of the summer. Since the nitrate is also present in low concentrations, most of the summer regeneration of nitrate must be very slow. The slow turnover of particulate N, low nutrient concentrations, slow rate of uptake relative to their ability to take up nitrogen, and the high affinity for ammonia (low Kt) suggest that in summer the primary productivity of the Lower Great Lakes is restricted by nitrogen deficiency.Key words: ammonia, nitrate, Lower Great Lakes

scholarly journals Technical Note: A comparison of two empirical approaches to estimate in-stream nutrient net uptake

2010 ◽  
Vol 7 (5) ◽  
pp. 7527-7542
Author(s):  
D. von Schiller ◽  
S. Bernal ◽  
E. Martí
Keyword(s):  
Mass Balance ◽  
Nutrient Uptake ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Data Set ◽  
Advantages And Disadvantages ◽  
Balance Approach ◽  
Uptake Rates ◽  
Empirical Approaches ◽  
Mass Balance Approach

Abstract. To establish the relevance of in-stream processes on nutrient export at catchment scale it is important to accurately estimate whole-reach net nutrient uptake rates that consider both uptake and release processes. Two empirical approaches have been used in the literature to estimate these rates: (a) the mass balance approach, which considers changes in nutrient loads corrected by groundwater inputs between two stream locations separated by a certain distance, and (b) the spiralling approach, which is based on the patterns of longitudinal variation in ambient nutrient concentrations along a reach following the nutrient spiralling concept. In this study, we compared the estimates of in-stream net nutrient uptake rates of nitrogen (N) and the associated uncertainty obtained with these two approaches at different ambient conditions using a data set of monthly samplings in two contrasting stream reaches during two hydrological years. The rates calculated with the mass balance approach tended to be higher than those calculated with the spiralling approach but only at high ambient N concentrations. Uncertainty associated with these estimates also differed between both approaches, especially for ammonium due to the lack of significant longitudinal patterns in concentration. The advantages and disadvantages of each of the approaches are discussed.

Short-term effects of carbon source on the competition of polyphosphate accumulating organisms and glycogen accumulating organisms

2004 ◽  
Vol 50 (10) ◽  
pp. 139-144 ◽  
Author(s):  
A. Oehmen ◽  
Z. Yuan ◽  
L.L. Blackall ◽  
J. Keller
Keyword(s):  
Carbon Source ◽  
In Situ Hybridisation ◽  
Operating Conditions ◽  
Fluorescence In Situ Hybridisation ◽  
Biological Phosphorus Removal ◽  
Short Term ◽  
Uptake Rates ◽  
Polyphosphate Accumulating Organisms ◽  
The Impact ◽  
Short Term Effects

The effectiveness of enhanced biological phosphorus removal (EBPR) systems is directly affected by the competition of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). This study investigated the short-term effects of carbon source on PAO and GAO performance. The tests were designed to clearly determine the impact of volatile fatty acid (VFA) composition on the performance of two types of biomass, one enriched for PAOs and the other for GAOs. The two populations were enriched in separate reactors using identical operating conditions and very similar influent compositions with acetate as the sole carbon source. The only difference was that a very low level of phosphorus was present in the influent to the GAO reactor. The abundance of PAOs and GAOs was quantified using fluorescence in-situ hybridisation. The results clearly show that there are some very distinctive differences between PAOs and GAOs in their ability to utilise different carbon substrates. While both are able to take up acetate rapidly and completely, the GAOs are far slower at consuming propionate than the PAOs during short-term substrate changes. This provides a potentially highly valuable avenue to influence the competition between PAOs and GAOs. Other VFAs studied seem to be less usable in the short term by both PAOs and GAOs, as indicated by their much lower uptake rates.

scholarly journals Glacier dynamics at Helheim and Kangerdlugssuaq glaciers, southeast Greenland, since the Little Ice Age

2014 ◽  
Vol 8 (4) ◽  
pp. 1497-1507 ◽  
Author(s):  
S. A. Khan ◽  
K. K. Kjeldsen ◽  
K. H. Kjær ◽  
S. Bevan ◽  
A. Luckman ◽  
...  
Keyword(s):  
Mass Balance ◽  
Little Ice Age ◽  
Ice Age ◽  
Short Term ◽  
Velocity Change ◽  
Outlet Glacier ◽  
Episodic Events ◽  
Highly Sensitive ◽  
Decadal Scale ◽  
Speed Up

Abstract. Observations over the past decade show significant ice loss associated with the speed-up of glaciers in southeast Greenland from 2003, followed by a deceleration from 2006. These short-term, episodic, dynamic perturbations have a major impact on the mass balance on the decadal scale. To improve the projection of future sea level rise, a long-term data record that reveals the mass balance beyond such episodic events is required. Here, we extend the observational record of marginal thinning of Helheim and Kangerdlugssuaq glaciers from 10 to more than 80 years. We show that, although the frontal portion of Helheim Glacier thinned by more than 100 m between 2003 and 2006, it thickened by more than 50 m during the previous two decades. In contrast, Kangerdlugssuaq Glacier underwent minor thinning of 40–50 m from 1981 to 1998 and major thinning of more than 100 m after 2003. Extending the record back to the end of the Little Ice Age (prior to 1930) shows no thinning of Helheim Glacier from its maximum extent during the Little Ice Age to 1981, while Kangerdlugssuaq Glacier underwent substantial thinning of 230 to 265 m. Comparison of sub-surface water temperature anomalies and variations in air temperature to records of thickness and velocity change suggest that both glaciers are highly sensitive to short-term atmospheric and ocean forcing, and respond very quickly to small fluctuations. On century timescales, however, multiple external parameters (e.g. outlet glacier shape) may dominate the mass change. These findings suggest that special care must be taken in the projection of future dynamic ice loss.

scholarly journals Impact of vertical and horizontal advection on nutrient distribution in the southeast Pacific

Ocean Science ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 1003-1011 ◽  
Author(s):  
Bàrbara Barceló-Llull ◽  
Evan Mason ◽  
Arthur Capet ◽  
Ananda Pascual
Keyword(s):  
Vertical Velocity ◽  
Nitrate Uptake ◽  
Austral Summer ◽  
Lagrangian Particle ◽  
Nutrient Distribution ◽  
Uptake Rates ◽  
Southeast Pacific ◽  
Omega Equation ◽  
The Impact ◽  
Initial Distributions

Abstract. An innovative approach is used to analyze the impact of vertical velocities associated with quasi-geostrophic (QG) dynamics on the redistribution and uptake of nitrate in the southeast Pacific (SEP). A total of 12 years of vertical and horizontal currents are derived from an observation-based estimate of the ocean state. Horizontal velocities are obtained through the application of thermal wind balance to weekly temperature and salinity fields. Vertical velocities are estimated by integration of the QG omega equation. Seasonal variability of the synthetic vertical velocity and kinetic energy associated with the horizontal currents is coincident, with peaks in austral summer (November–December) in accord with published observations. The impact of vertical velocity on SEP nitrate uptake rates is assessed by using two Lagrangian particle tracking experiments that differ according to vertical forcing (ω = ωQG vs. ω = 0). From identical initial distributions of nitrate-tagged particles, the Lagrangian results show that vertical motions induce local increases in nitrate uptake reaching up to 30 %. Such increases occur in low uptake regions with high mesoscale activity. Despite being weaker than horizontal currents by a factor of up to 10−4, vertical velocity associated with mesoscale activity is demonstrated to make an important contribution to nitrate uptake, hence productivity, in low uptake regions.

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