Development and Intercalibration of Ultraviolet Solar Actinometers

Jankowski, Joseph J.; Kieber, David J.; Mopper, Kenneth; Neale, Patrick J.

doi:10.1562/0031-8655(2000)0710431daious2.0.co2

Cited by 30 publications

(64 citation statements)

References 43 publications

(29 reference statements)

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“…The nitrate and nitrite actinometers employed in this study were developed by Jankowski (1999) and Jankowski et al (1999Jankowski et al ( , 2000. However, two modifications were made to adapt these actinometers to incubations in Antarctic waters.…”

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

“…All samples were allowed to equilibrate to room temperature after an irradiation and were subsequently analyzed for SA production by high performance liquid chromatography (HPLC) with fluorescence detection. Once SA concentrations were determined, quantum yields were calculated according to Jankowski (1999).…”

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

“…In many cases, the nitrate and nitrite actinometers were wrapped with Mylar D film (Dupont Corp.), an inexpensive long bandpass filter that eliminated much of the UVB radiation (290 -320 nm) in the actinometers (for a transmission spectrum of Mylar D refer to Jankowski et al, 2000). The thickness of the Mylar D film was 0.10 mm for the Palmer Station study and 0.16 mm for the cruises.…”

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

“…This filter served to modify the response band of the actinometers and to reduce the photodegradation of salicylic acid produced in the actinometers. Further details on the use of the Mylar D and the degradation of salicylic acid are presented in Jankowski (1999) and Jankowski et al (2000). If Mylar D is not available, then 0.13 mm thick Melinex can be used.…”

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

“…To determine the integrated irradiance for the nitrate actinometer in quartz tubing with no Mylar D filter, the photochemical loss of SA must be considered (Jankowski et al, 2000). The photochemical degradation of salicylic acid was accounted for using the following equation for the integrated irradiance:…”

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

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Chemical “light meters” for photochemical and photobiological studies

et al. 2007

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Nitrate and nitrite solar actinometers or chemical "light meters" were used to quantify light doses in photochemical and photobiological experiments involving dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) cycling. Light doses were calculated based on the photochemical production of salicylic acid (SA) from benzoic acid in these actinometers, with SA quantified by either spectrofluorometry or high performance liquid chromatography. Nitrate and nitrite actinometers were modified for deployment at low temperatures in Antarctic waters by addition of sodium chloride as a freezing point depressant. The addition of salt did not affect the solar response of the actinometers; however, the solar response did change slightly with latitude. In the Antarctic, peak response wavelengths (and bandwidths) for the Mylar D-wrapped actinometers in quartz tubing were 326 nm (319 -333 nm) and 353 nm (325 -380 nm) for nitrate and nitrite, respectively, and these were 2 -5 nm blue shifted compared to the peak response wavelengths and bandwidths observed in the Sargasso Sea. Excellent agreement was observed when comparing the integrated irradiance determined with the actinometers to that determined with a spectroradiometer. Likewise, diffuse attenuation coefficients for downwelling irradiance (K d (l)) calculated from water column actinometer measurements agreed well with K d (l) values calculated from irradiance measurements determined with a Biospherical PUV-511 profiling radiometer. Actinometers were used to measure light doses in experiments involving DMS and DMSP transformations during several field campaigns in the Ross Sea, Antarctica and the Sargasso Sea. Based on actinometer measurements, it was determined that DMS photolysis was dependent on UV irradiation between approximately 325 -380 nm, while biological consumption rates of DMS and DMSP were inhibited by radiation at wavelengths less than approximately 333 nm. When DMS photolysis rate constants were expressed in terms of light dose rather than time, it was possible to 1) directly determine photolysis rate constants in the water column and 2) directly compare photolysis rate constants across diverse oceanographic regions.

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Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

Section: Nitrate and Nitrite Actinometrymentioning

confidence: 99%

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Chemical “light meters” for photochemical and photobiological studies

et al. 2007

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Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean

Aarnos

Gélinas

Kasurinen

et al. 2018

Global Biogeochemical Cycles

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When terrigenous dissolved organic carbon (tDOC) rich in chromophoric dissolved organic matter (tCDOM) enters the ocean, solar radiation mineralizes it partially into dissolved inorganic carbon (DIC). This study addresses the amount and the rates of DIC photoproduction from tDOC and the area of ocean required to photomineralize tDOC. We collected water samples from 10 major rivers, mixed them with artificial seawater, and irradiated them with simulated solar radiation to measure DIC photoproduction and the photobleaching of tCDOM. The linear relationship between DIC photoproduction and tCDOM photobleaching was used to estimate the amount of photoproduced DIC from the tCDOM fluxes of the study rivers. Solar radiation was estimated to mineralize 12.5 ± 3.7 Tg C yr−1 (10 rivers)−1 or 18 ± 8% of tDOC flux. The irradiation experiments also approximated typical apparent spectral quantum yields for DIC photoproduction (ϕλ) over the entire lifetime of the tCDOM. Based on ϕλs and the local solar irradiances in river plumes, the annual areal DIC photoproduction rates from tDOC were calculated to range from 52 ± 4 (Lena River) to 157 ± 2 mmol C m−2 yr−1 (Mississippi River). When the amount of photoproduced DIC was divided by the areal rate, 9.6 ± 2.5 × 106 km2 of ocean was required for the photomineralization of tDOC from the study rivers. Extrapolation to the global tDOC flux yields 45 (31–58) Tg of photoproduced DIC per year in the river plumes that cover 34 (25–43) × 106 km2 of the ocean.

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Apparent quantum yield of photochemical dissolved organic carbon mineralization in lakes

Koehler

Broman²,

Tranvik

2016

Limnol. Oceanogr.

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Up to one tenth of the carbon dioxide (CO2) emissions from inland waters worldwide are directly induced by the photochemical mineralization of dissolved organic matter (DOM). The photochemical production of dissolved inorganic carbon (DIC) per photon absorbed by chromophoric DOM (CDOM) decreases exponentially with increasing irradiance wavelength, and is commonly described by an “apparent quantum yield” (AQY) spectrum. Although an essential model parameter to simulate photochemical mineralization the AQY remains poorly constrained. Here, the AQY of photochemical DIC production for 25 lakes located in boreal, polar, temperate, and tropical areas, including four saline lagoons, was measured. The wavelength‐integrated AQY (300–500 nm; mol DIC mol CDOM‐absorbed photons−1) ranged from 0.05 in an Antarctic lake to 0.61 in a humic boreal lake, averaging 0.24 ± 0.03 SE. AQY was positively linearly correlated with the absorption coefficient at 420 nm (a420) as a proxy for CDOM content (R2 of 0.64 at 300 nm and 0.26 at 400 nm), with specific UV absorption coefficients as a proxy for DOM aromaticity (R2 of 0.56 at 300 nm and 0.38 at 400 nm), and with the humification index (R2 of 0.41 at 300 nm and 0.42 at 400 nm). Hence, a considerable fraction of the AQY variability was explained by water optical properties in inland waters. The correlation of AQY with a420 opens up the possibility to improve large‐scale model estimates of sunlight‐induced CO2 emissions from inland waters based on water color information derived by satellite remote sensing.

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Development and Intercalibration of Ultraviolet Solar Actinometers

Cited by 30 publications

References 43 publications

Chemical “light meters” for photochemical and photobiological studies

Chemical “light meters” for photochemical and photobiological studies

Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean

Apparent quantum yield of photochemical dissolved organic carbon mineralization in lakes

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