An Evaluation of Nitrate, fDOM, and Turbidity Sensors in New Hampshire Streams

Snyder, Lisle; Potter, Jody D.; McDowell, William H.

doi:10.1002/2017wr020678

Cited by 51 publications

(62 citation statements)

References 25 publications

(54 reference statements)

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“…Despite these well‐documented relationships between DOC and discharge at other sites we did not observe a response of DOC concentration to discharge in this 15‐year record of weekly observations. The Lamprey River was also the only site of 10 streams and rivers throughout New Hampshire that exhibited this sort of chemostatic relationship for fluorescent DOM (FDOM; Koenig et al, ), which is an effective proxy for DOC concentration in these streams (Snyder et al, ). Koenig et al () did observe predictable variability during individual storm events, with counterclockwise hysteresis in FDOM in both the Lamprey River and its tributaries.…”

Section: Discussionmentioning

confidence: 99%

Multiyear Trends in Solute Concentrations and Fluxes From a Suburban Watershed: Evaluating Effects of 100‐Year Flood Events

et al. 2018

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Anthropogenic activities have increased solute concentrations and fluxes in rivers globally.Increases in salt, dissolved organic carbon, and inorganic nutrients have been attributed to changes in atmospheric deposition, road salt and fertilizer application, and urbanization. Extremely large flood events, which are increasing in frequency and duration, could also alter river chemistry by flushing various solute reservoirs within watersheds and effectively "resetting" the linkages between land and river. We evaluated changes in concentrations and fluxes of inorganic nutrients, dissolved organic matter, and salts and major ions across 12 to 15 years in a rural-suburban watershed in New Hampshire, USA. During this period, the human imprint on the landscape (impervious surfaces and population density) increased, but two 100-year flood events also occurred. We found that concentrations and fluxes of chloride and potassium, fluxes of all other major ions, and concentrations of dissolved organic carbon declined over time, but concentrations and fluxes of inorganic nutrients and dissolved organic nitrogen were unchanged. The minor declines in concentrations were of similar magnitude to declines previously observed in other watersheds that did not experience extreme flood events. We observed a shift in nitrate (NO 3 À ) concentration-discharge behavior from enrichment in the years prior to and including the floods to chemostasis after the floods, but for both time periods NO 3 À concentrations were weakly related to discharge. Our results suggest a limited role of extreme events in the biogeochemistry of urbanizing watersheds and emphasize the importance of long-term records and multiple analytical approaches to understand the dynamics of complex watersheds. Key Points:• Small decreases in concentrations and fluxes of salts and major ions were observed over 12 years despite an increase in the human footprint • Small (<1% of mean annual) decreases in DOC concentrations were observed over a 15-year period, but DOC did not respond to discharge • Occurrence of two 100-year flood events had little, if any, effect on multiyear trends in concentrations, fluxes, or C-Q relationships Supporting Information:• Figure S1

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Section: Discussionmentioning

confidence: 99%

Multiyear Trends in Solute Concentrations and Fluxes From a Suburban Watershed: Evaluating Effects of 100‐Year Flood Events

et al. 2018

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“…Detailed methods describing the deployment and efficacy of the in‐situ fDOM sensors are described in Snyder et al (), but are also described briefly here. The ten sites were equipped with EXO2 water quality sondes by YSI Inc. (Xylem Inc., Yellow Springs, OH, USA) with a YSI fDOM sensor measuring every 15 minutes at an excitation‐emission wavelength pair of 365 and 480 nm.…”

Section: Methodsmentioning

confidence: 99%

“…Detailed methods describing the deployment and efficacy of the insitu fDOM sensors are described in Snyder et al (2018), but are also described briefly here. The ten sites were equipped with EXO2 water Figure 1.…”

Section: In Situ Fdom Sensorsmentioning

confidence: 99%

Using In‐Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

Wymore

Potter

Rodriguez-Cardona

et al. 2018

Water Resources Research

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The advent of high‐frequency in situ optical sensors provides new opportunities to study the biogeochemistry of dissolved organic matter (DOM) in aquatic ecosystems. We used fDOM (fluorescent dissolved organic matter) to examine the spatial and temporal variability in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) across a heterogeneous stream network that varies in NO3− concentration. Across the ten study streams fDOM explained twice the variability in the concentration of DOC (r2 = 0.82) compared to DON (r2 = 0.39), which suggests that the N‐rich fraction of DOM is either more variable in its sources or more bioreactive than the more stable C‐rich fraction. Among sites, DON molar fluorescence was approximately 3x more variable than DOC molar fluorescence and was correlated with changes in inorganic N, indicating that DON is both more variable in composition as well as highly responsive to changes in inorganic N. Laboratory results also indicate that the fDOM sensors we used perform as well as the excitation‐emission wavelength pair generally referred to as the “tryptophan‐like” peak when measured under laboratory conditions. However, since neither the field sensor not the laboratory measurements explained a large percentage of variation in DON concentrations, challenges still remain for monitoring the ambient pool of dissolved organic nitrogen. Sensor networks provide new insights into the potential reactivity of DOM and the variability in DOC and DON biogeochemistry across sites. These insights are needed to build spatially explicit models describing organic matter dynamics and water quality.

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“…Moreover, the research in this field has increased, in the past five years, with several in situ measurement studies on the quality of groundwater (for example, Li et al, 2016a;Sorensen et al, 2018a), freshwater (Khamis et al, 2015;Snyder et al, 2018), marine water (Chen et al, 2015;Cyr et al, 2017) and engineered water systems (Carstea et al, 2018;Mladenov et al, 2018;Shutova et al, 2016;Singh et al, 2015). This paper aims to review the advances in water quality measurements using in situ fluorescence devices for detection of fluorescence emitted by DOM in the ultraviolet (UVA -320 -400 nm) and blue light regions (430nm), and their characterization, in marine, freshwater, groundwater and engineered water systems.…”

Section: Introductionmentioning

confidence: 99%

In situ fluorescence measurements of dissolved organic matter: A review

Cârstea

Popa

Baker

et al. 2020

Science of The Total Environment

102

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There is a need for an inexpensive, reliable and fast monitoring tool to detect contaminants in a short time, for quick mitigation of pollution sources and site remediation, and for characterisation of natural dissolved organic matter (DOM). Fluorescence spectroscopy has proven to be an excellent technique in quantifying aquatic DOM, from autochthonous, allochthonous or anthropogenic sources. This paper reviews the advances in in situ fluorescence measurements of DOM and pollutants in various water environments. Studies have demonstrated, using high temporal-frequency DOM fluorescence data, that marine autochthonous production of DOM is highly complex and that the allochthonous input of DOM from freshwater to marine water can be predicted. Furthermore, river measurement studies found a delayed fluorescence response of DOM following precipitation compared to turbidity and discharge, with various lags, depending on season, site and input of dissolved organic carbon (DOC) concentration. In addition, research has shown that blue light fluorescence (emission = 430-500 nm) can be a good proxy for DOC, in environments with terrestrial inputs, and ultraviolet fluorescence (emission = UVA-320-400 nm) for biochemical oxygen demand, and also E. coli in environments with sanitation issues. The correction of raw fluorescence data improves the relationship between fluorescence intensity and these parameters. This review also presents the specific steps and parameters that must be considered before and 2 during in situ fluorescence measurement session for a harmonised qualitative and quantitative protocol. Finally, the strengths and weaknesses of the research on in situ fluorescence are identified.

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An Evaluation of Nitrate, fDOM, and Turbidity Sensors in New Hampshire Streams

Cited by 51 publications

References 25 publications

Multiyear Trends in Solute Concentrations and Fluxes From a Suburban Watershed: Evaluating Effects of 100‐Year Flood Events

Multiyear Trends in Solute Concentrations and Fluxes From a Suburban Watershed: Evaluating Effects of 100‐Year Flood Events

Using In‐Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

In situ fluorescence measurements of dissolved organic matter: A review

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