6 research outputs found
Calibration of the comprehensive NDHA-N<sub>2</sub>O dynamics model for nitrifier-enriched biomass using targeted respirometric assays
The NDHA model comprehensively describes nitrous oxide (N2O) producing
pathways by both autotrophic ammonium oxidizing and heterotrophic bacteria. The
model was calibrated via a set of targeted extant respirometric assays using
enriched nitrifying biomass from a lab-scale reactor. Biomass response to
ammonium, hydroxylamine, nitrite and N2O additions under aerobic and anaerobic
conditions were tracked with continuous measurement of dissolved oxygen (DO)
and N2O. The sequential addition of substrate pulses allowed the isolation of
oxygen-consuming processes. The parameters to be estimated were determined by
the information content of the datasets using identifiability analysis. Dynamic
DO profiles were used to calibrate five parameters corresponding to endogenous,
nitrite oxidation and ammonium oxidation processes. The subsequent N2O
calibration was not significantly affected by the uncertainty propagated from
the DO calibration because of the high accuracy of the estimates. Five
parameters describing the individual contribution of three biological N2O
pathways were estimated accurately (variance/mean < 10% for all estimated
parameters). The NDHA model response was evaluated with statistical metrics
(F-test, autocorrelation function). The 95% confidence intervals of DO and N2O
predictions based on the uncertainty obtained during calibration are studied
for the first time. The measured data fall within the 95% confidence interval
of the predictions, indicating a good model description. Overall, accurate
parameter estimation and identifiability analysis of ammonium removal
significantly decreases the uncertainty propagated to N2O production, which is
expected to benefit N2O model discrimination studies and reliable full scale
applications.Comment: Main text (27 pages, 7 figures, 2 tables) and Supplementary
Information (25 pages, 10 sections
Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments
The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations
Effects of Consecutive Extreme Weather Events on a Temperate Dystrophic Lake: A Detailed Insight into Physical, Chemical and Biological Responses
Between May and July 2018, Ireland experienced an exceptional heat wave, which broke long-term temperature and drought records. These calm, stable conditions were abruptly interrupted by a second extreme weather event, Atlantic Storm Hector, in late June. Using high-frequency monitoring data, coupled with fortnightly biological sampling, we show that the storm directly affected the stratification pattern of Lough Feeagh, resulting in an intense mixing event. The lake restabilised quickly after the storm as the heatwave continued. During the storm there was a three-fold reduction in Schmidt stability, with a mixed layer deepening of 9.5 m coinciding with a two-fold reduction in chlorophyll a but a three-fold increase in total zooplankton biomass. Epilimnetic respiration increased and net ecosystem productivity decreased. The ratio of total nitrogen:total phosphorus from in-lake versus inflow rivers was decoupled, leading to a cascade effect on higher trophic levels. A step change in nitrogen:phosphorus imbalances suggested that the zooplankton community shifted from phosphorus to nitrogen nutrient constraints. Such characterisations of both lake thermal and ecological responses to extreme weather events are relatively rare but are crucial to our understanding of how lakes are changing as the impacts of global climate change accelerate
Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments
International audienceThe relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations
Environmental variability in aquatic ecosystems : Avenues for future multifactorial experiments
The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations
Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments
Abstract The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variabilityâfocused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations