Synthesis of data from high-frequency nutrient and associated biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California

Downing, Bryan D.; Bergamaschi, Brian A.; Kraus, Tamara E.C.

doi:10.3133/sir20175066

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…High-frequency monitoring of drainage outletsfor nutrient concentrations and related ancillary water-quality parameters such as temperature, dissolved oxygen, and pH-could be used for better resolution of mass flux estimates and shifting nutrient biogeochemistry in island drainage. Similar recent work, enabled by deployment of high-frequency sensor networks, showed nutrient dynamics can change at timescales of hours, days, and weeks in the Delta (Downing et al 2017;Kraus et al 2017), and we suspect a similar high-frequency data set for multiple island drainage sites could help resolve some of the variability seen in this study and https://doi.org/10.15447/sfews.2022v20iss2art5 companion work by Richardson et al (2020). Such monitoring would also likely generate more refined and accurate load estimates both within and across water years.…”

Section: Study Limitations and Applicationssupporting

confidence: 64%

Nutrient and Trace Element Contributions from Drained Islands in the Sacramento–San Joaquin Delta, California

Richardson¹,

Fackrell²,

Kraus³

et al. 2022

SFEWS

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Inventorying nutrient and trace element sources in the Sacramento-San Joaquin Delta (the Delta) is critical to understanding how changes—including alterations to point source inputs such as upgrades to the Sacramento Regional Wastewater Treatment Plant (SRWTP) and landscape-scale changes related to wetland restoration—may alter the Delta’s water quality. While island drains are a ubiquitous feature of the Delta, limited data exist to evaluate island drainage mass fluxes in this system. To better constrain inputs from island drains, we measured monthly discharge along with nutrient and trace element concentrations in island drainage on three Delta islands and surrounding rivers from June 2017 to September 2018. These data were used to calculate island-level fluxes and then upscaled to estimate Delta-wide contributions from island drains. Based on these results, we present (1) new estimates of gross and net nutrient and trace element fluxes from Delta island drains, and (2) concomitant N stable isotope data to improve our understanding of island N cycling. Over 60% of nearly all island drainage gross nutrient and trace element loads occurred in winter and spring. Upscaled island drainage net annual total nitrogen (TN), total dissolved nitrogen (TDN), and NH4+ loads comprised an estimated 9%, 7%, and 4%, respectively, of annual inputs to this system in 2018, before the SRWTP upgrade. Under a post-upgrade scenario, we estimated net annual island drainage TDN contributions to increase to 11% and NH4+ contributions to 45% of total Delta inputs as the SRWTP NH4+ load diminished to near zero. Our results suggest that island drainage is a measurable N source that has likely become increasingly important now that the SRWTP upgrade is complete. With over 200 potential active outfalls, these inputs may affect aquatic biogeochemical cycling in many regions of the Delta, especially in areas with long residence times.

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Section: Study Limitations and Applicationssupporting

confidence: 64%

Nutrient and Trace Element Contributions from Drained Islands in the Sacramento–San Joaquin Delta, California

Richardson¹,

Fackrell²,

Kraus³

et al. 2022

SFEWS

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“…Like many other large temperate rivers, in the absence of anthropogenic inputs the Sacramento River typically has low concentrations of

{NO}_{3}^{-}

(<15 µ M ), except during storm events when hydrologic connectivity to upstream terrestrial sources leads to elevated concentrations (Downing et al, ; Kratzer et al, ). While the total annual nitrogen loads exported from the Sacramento River to the downstream estuary is predominantly attributed to diffuse upstream sources (Saleh & Domagalski, ), those inputs typically occur during high flow storm events when constituents in the water column rapidly transit the ecosystem (i.e., short travel times).…”

Section: Discussionmentioning

confidence: 99%

Using Paired In Situ High Frequency Nitrate Measurements to Better Understand Controls on Nitrate Concentrations and Estimate Nitrification Rates in a Wastewater‐Impacted River

Kraus

O'Donnell

Downing

et al. 2017

Water Resources Research

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We used paired continuous nitrate ( NO3–) measurements along a tidally affected river receiving wastewater discharge rich in ammonium ( NH4+) to quantify rates of change in NO3– concentration ( RΔNO3) and estimate nitrification rates. NO3– sensors were deployed 30 km apart in the Sacramento River, California (USA), with the upstream station located immediately above the regional wastewater treatment plant (WWTP). We used a travel time model to track water transit between the stations and estimated RΔNO3 every 15 min (October 2013 to September 2014). Changes in NO3– concentration were strongly related to water temperature. In the presence of wastewater, RΔNO3 was generally positive, ranging from about 7 µM d−1 in the summer to near zero in the winter. Numerous periods when the WWTP halted discharge allowed the RΔNO3 to be estimated under no‐effluent conditions and revealed that in the absence of effluent, net gains in NO3– were substantially lower but still positive in the summer and negative (net sink) in the winter. Nitrification rates of effluent‐derived NH4 ( RNitrific_E) were estimated from the difference between RΔNO3 measured in the presence versus absence of effluent and ranged from 1.5 to 3.4 µM d−1, which is within literature values but tenfold greater than recently reported for this region. RNitrific_E was generally lower in winter (∼2 µM d−1) than summer (∼3 µM d−1). This in situ, high frequency approach provides advantages over traditional discrete sampling, incubation, and tracer methods and allows measurements to be made over broad areas for extended periods of time. Incorporating this approach into environmental monitoring programs can facilitate our ability to protect and manage aquatic systems.

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“…To date, these data have been used largely to explore nitrate load timing, rate, and magnitude and thus prediction capabilities for downstream environmental consequences (Jones et al, ; Pellerin et al, , ). To our knowledge, across‐scale nitrate process dynamics have not been systematically investigated in heavily agriculturally managed landscapes, although some work has occurred in less impacted watersheds (Aubert et al, ; Downing et al, ). This is, in part, because the high‐frequency nitrate data generated from these sensors are only recently long enough to use frequency analysis tools on, such as spectral analysis among others, to extract information about the signature of different processes on change in variability in NO 3 − across a range of scales.…”

Section: Introductionmentioning

confidence: 99%

High‐Frequency Sensor Data Reveal Across‐Scale Nitrate Dynamics in Response to Hydrology and Biogeochemistry in Intensively Managed Agricultural Basins

Hansen

Singh

2018

JGR Biogeosciences

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Excess nitrate in rivers draining intensively managed agricultural watersheds has caused coastal hypoxic zones, harmful algal blooms, and degraded drinking water. Hydrology and biogeochemical transformations influence nitrate concentrations by changing nitrate supply, removal, and transport. For the Midwest Unites States, where much of the land is used for corn and soybean production, a better understanding of the response of nitrate to hydrology and biogeochemistry is vital in the face of high nitrate concentrations coupled with projected increases of precipitation frequency and magnitude. In this study, we capitalized on the availability of spatially and temporally extensive sensor data in the region to evaluate how nitrate concentration (NO 3 À ) interacts with discharge (Q) and water temperature (T) within eight watersheds in Iowa, United States, by evaluating land use characteristics and multiscale temporal behavior from 5-year, high-frequency, time series records. We show that power spectral density of Q, NO 3 À , and T, all exhibit power law behavior with slopes greater than 2, implying temporal self-similarity for a range of scales. NO 3 À was strongly cross correlated with Q for all sites and correlation increased significantly with drainage area across sites. Peak NO 3 À increased significantly with crop coverage across watersheds.Temporal offsets in peak NO 3 À and peak Q, seen at all study sites, reduced the impact of extreme events. This study illustrates a relatively new approach to evaluating environmental sensor data and revealed characteristics of watersheds in which extreme discharge events have the greatest consequences.Plain Language Summary Nitrate export from the Midwest United States has caused water quality degradation extending from the Midwest, where concentrations exceed drinking water limits, to the northern Gulf of Mexico, where it contributes to the formation of the Dead Zone. Climate models predict that precipitation in the Midwest will increase; therefore, understanding the response of nitrate to streamflow (discharge) is vital. In this study, we analyzed the patterns within nitrate, discharge and temperature sensor data over time for eight agricultural watersheds to determine how nitrate concentration is related to discharge or water temperature. From this, we evaluated the relative importance of hydrology vs. nitrate removal or release in controlling nitrate export. We show that nitrate, discharge, and temperature all exhibit self-similar characteristics across a range of temporal scales and that the percent of land used for agriculture was predictive of peak nitrate concentration. We found that nitrate was strongly related to discharge and that the similarity between nitrate and discharge increased with watershed size. However, peak nitrate concentration generally lagged behind peak discharge resulting in maximum peak nitrate loads often occurring at intermediate-sized, not extreme, events.Key Points:• Discharge, nitrate concentration, and temperature exhibited power law behavio...

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Synthesis of data from high-frequency nutrient and associated biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California

Cited by 7 publications

References 5 publications

Nutrient and Trace Element Contributions from Drained Islands in the Sacramento–San Joaquin Delta, California

Nutrient and Trace Element Contributions from Drained Islands in the Sacramento–San Joaquin Delta, California

Using Paired In Situ High Frequency Nitrate Measurements to Better Understand Controls on Nitrate Concentrations and Estimate Nitrification Rates in a Wastewater‐Impacted River

High‐Frequency Sensor Data Reveal Across‐Scale Nitrate Dynamics in Response to Hydrology and Biogeochemistry in Intensively Managed Agricultural Basins

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