scholarly journals Pressure correction for the computation of nitrate concentrations in seawater using an in situ ultraviolet spectrophotometer

2017 ◽  
Vol 15 (10) ◽  
pp. 897-902 ◽  
Author(s):  
Carole M. Sakamoto ◽  
Kenneth S. Johnson ◽  
Luke J. Coletti ◽  
Hans W. Jannasch
Keyword(s):  
Pressure Correction ◽  
Nitrate Concentrations ◽  
Ultraviolet Spectrophotometer

Computation of nitrate concentrations in turbid coastal waters using an in situ ultraviolet spectrophotometer

2011 ◽  
Vol 65 (4) ◽  
pp. 456-460 ◽  
Author(s):  
O. Zielinski ◽  
D. Voß ◽  
B. Saworski ◽  
B. Fiedler ◽  
A. Körtzinger
Keyword(s):  
Coastal Waters ◽  
Nitrate Concentrations ◽  
Ultraviolet Spectrophotometer

scholarly journals An Improved Algorithm for Measuring Nitrate Concentrations in Seawater Based on Deep-Ultraviolet Spectrophotometry: A Case Study of the Aoshan Bay Seawater and Western Pacific Seawater

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 965
Author(s):  
Xingyue Zhu ◽  
Kaixiong Yu ◽  
Xiaofan Zhu ◽  
Juan Su ◽  
Chi Wu
Keyword(s):  
Weighted Average ◽  
Measuring Method ◽  
Western Pacific ◽  
Nitrate Concentrations ◽  
Deep Ultraviolet ◽  
Ultraviolet Spectrometer ◽  
Seawater Samples ◽  
Reflection Probe

Nowadays, it is still a challenge for commercial nitrate sensors to meet the requirement of high accuracy in a complex water. Based on deep-ultraviolet spectral analysis and a regression algorithm, a different measuring method for obtaining the concentration of nitrate in seawater is proposed in this paper. The system consists of a deuterium lamp, an optical fiber splitter module, a reflection probe, temperature and salinity sensors, and a deep-ultraviolet spectrometer. The regression model based on weighted average kernel partial least squares (WA-KPLS) algorithm together with corrections for temperature and salinity (TSC) is established. After that, the seawater samples from Western Pacific and Aoshan Bay in Qingdao, China with the addition of various nitrate concentrations are studied to verify the reliability and accuracy of the method. The results show that the TSC-WA-KPLS algorithm shows the best results when compared against the multiple linear regression (MLR) and ISUS (in situ ultraviolet spectrophotometer) algorithms in the temperatures range of 4–25 °C, with RMSEP of 0.67 µmol/L for Aoshan Bay seawater and 1.08 µmol/L for Western Pacific seawater. The method proposed in this paper is suitable for measuring the nitrate concentration in seawater with higher accuracy, which could find application in the development of in-situ and real-time nitrate sensors.

Continuous determination of nitrate concentrations in situ

1989 ◽  
Vol 36 (9) ◽  
pp. 1407-1413 ◽  
Author(s):  
Kenneth S. Johnson ◽  
Carole M. Sakamoto-Arnold ◽  
Carl L. Beehler
Keyword(s):  
Nitrate Concentrations ◽  
Continuous Determination

scholarly journals How runoff components affect the export of DOC and nitrate: a long-term and high-frequency analysis

2017 ◽  
Author(s):  
Michael P. Schwab ◽  
Julian Klaus ◽  
Laurent Pfister ◽  
Markus Weiler
Keyword(s):  
High Frequency ◽  
Initial Conditions ◽  
Shallow Groundwater ◽  
High Temporal Resolution ◽  
Near Surface ◽  
Nitrate Concentrations ◽  
Nitrate Export ◽  
Dry Conditions

Abstract. We monitored dissolved organic carbon (DOC) and nitrate concentrations and fluxes in situ with a UV-Vis spectrometer for two years at a high temporal resolution of 15 minutes in the forested Weierbach headwater catchment. The catchment exhibits a characteristic double peak runoff response to incident rainfall during periods with wet initial conditions. When initial conditions are dry, only the first discharge peak occurs. During our observations, both DOC and nitrate concentrations increased during the first discharge peak, while only nitrate concentrations were elevated during the second discharge peak. Relying on additional biweekly end-member data of precipitation, throughfall, soil water and groundwater, we linked the first peak to near surface flowpaths and the second peak to shallow groundwater reactions and subsurface flowpaths. The mass export of DOC and nitrate is largely controlled by the discharge yield. Nevertheless, this relationship is altered by changing flowpaths during different wetness conditions in the catchment. Due to the absence of second discharge peaks during dry conditions, the DOC export is more relevant and the nitrate export is less relevant during dry catchment states. The study highlights the benefits of in-situ, long-term, and high-frequency monitoring for comparing DOC and nitrate export with runoff components that are changing rapidly during events as well as gradually between seasons.

scholarly journals Long-Term Nitrate Measurements in the Ocean Using the in situ Ultraviolet Spectrophotometer: Sensor Integration into the APEX Profiling Float

2013 ◽  
Vol 30 (8) ◽  
pp. 1854-1866 ◽  
Author(s):  
Kenneth S. Johnson ◽  
Luke J. Coletti ◽  
Hans W. Jannasch ◽  
Carole M. Sakamoto ◽  
Dana D. Swift ◽  
...  
Keyword(s):  
Lithium Batteries ◽  
Vertical Profile ◽  
Sensor Integration ◽  
Power Device ◽  
Vertical Profiles ◽  
Power Mode ◽  
Measurement Operation ◽  
Ultraviolet Spectrophotometer

Abstract Reagent-free optical nitrate sensors [in situ ultraviolet spectrophotometer (ISUS)] can be used to detect nitrate throughout most of the ocean. Although the sensor is a relatively high-power device when operated continuously (7.5 W typical), the instrument can be operated in a low-power mode, where individual nitrate measurements require only a few seconds of instrument time and the system consumes only 45 J of energy per nitrate measurement. Operation in this mode has enabled the integration of ISUS sensors with Teledyne Webb Research's Autonomous Profiling Explorer (APEX) profiling floats with a capability to operate to 2000 m. The energy consumed with each nitrate measurement is low enough to allow 60 nitrate observations on each vertical profile to 1000 m. Vertical resolution varies from 5 m near the surface to 50 m near 1000 m, and every 100 m below that. Primary lithium batteries allow more than 300 vertical profiles from a depth of 1000 m to be made, which corresponds to an endurance near four years at a 5-day cycle time. This study details the experience in integrating ISUS sensors into Teledyne Webb Research's APEX profiling floats and the results that have been obtained throughout the ocean for periods up to three years.

scholarly journals In situ Determination of Nitrate and Hydrogen Sulfide in the Baltic Sea Using an Ultraviolet Spectrophotometer

2018 ◽  
Vol 5 ◽  
Author(s):  
David Meyer ◽  
Ralf D. Prien ◽  
Louis Rautmann ◽  
Malte Pallentin ◽  
Joanna J. Waniek ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Baltic Sea ◽  
The Baltic Sea ◽  
The Baltic ◽  
Ultraviolet Spectrophotometer
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