Seasonal dynamics of colored dissolved material in the Sargasso Sea

Nelson, Norman B.; Siegel, David A.; Michaels, Anthony F.

doi:10.1016/s0967-0637(97)00106-4

Cited by 357 publications

(333 citation statements)

References 52 publications

Supporting

Mentioning

289

Contrasting

Unclassified

Order By: Relevance

“…In both summer profiles, DOS displayed a surface minimum and an increase into the upper thermocline, although in August 1999 a subsurface maximum was apparent. These are the first oceanic profiles for DOS, so no comparisons with previous work can be made, but the surface minimum and increase with depth were present in two different years, and the distributions of DOS were very similar to summertime profiles of the CDOM absorption coefficient in the Sargasso Sea (Nelson et al 1998; Fig. 3A).…”

Section: Resultsmentioning

confidence: 70%

Sources and cycling of carbonyl sulfide in the Sargasso Sea

Cutter

Filippino

2004

Limnology & Oceanography

View full text Add to dashboard Cite

The cycling of the radiatively important gas carbonyl sulfide (OCS) was studied in surface waters of the Sargasso Sea. In August 1999, surface OCS concentrations averaged 8.6 pmol L Ϫ1 , showed minor diel variations, and varied little with depth. An OCS precursor, total dissolved organic sulfur (DOS), was lowest at the surface (40 nmol L Ϫ1 ) and increased with depth. The photoproduction rate of OCS from in situ incubations averaged 9.6 pmol L Ϫ1 h Ϫ1 , whereas dark production was 7.0 pmol L Ϫ1 h Ϫ1 . Apparent quantum yields were 10 Ϫ5 -10 Ϫ7 from 313-436 nm and varied with the water depth irradiated. In March 2000, there were strong diel variations in surface OCS (highest in late afternoon; overall average, 16.9 pmol L Ϫ1 ). Depth profiles in the afternoon showed surface water maxima and decreases with depth, whereas DOS had a surface maximum of 419 nmol L Ϫ1 and decreased with depth. Dark production was 4.0 pmol L Ϫ1 h Ϫ1 . Modeling of the diel cycle suggested a photoproduction rate of 16.4 pmol L Ϫ1 h Ϫ1 . Overall, the photochemical production of OCS strongly depended on DOS and chromophoric dissolved organic matter, whereas dark production was influenced by the presence of particles and perhaps microbial respiration, showing a direct biotic influence on OCS cycling.Of the sulfur gases emitted from the ocean (dimethyl sulfide, carbonyl sulfide [OCS], and hydrogen sulfide; Andreae 1990), perhaps the most attention has been paid to dimethyl sulfide because of its potential marine biogeochemistry-climate feedbacks (Charlson et al. 1987). However, the oceanic source of OCS is also quantitatively significant, because this gas has an extremely long tropospheric residence time (1-4 yr; Khalil and Rasmussen 1984) and diffuses into the stratosphere, where it maintains the stratospheric sulfate aerosol layer and thereby affects the planetary radiation budget (Crutzen 1976;Turco et al. 1980;Hofmann 1990). Moreover, the hydrolysis of OCS produces dissolved hydrogen sulfide, which can then affect the cycling of many trace metals . Thus, the marine cycling of OCS has both atmospheric and oceanic consequences.Unlike the other marine sulfur gases, OCS has extreme temporal and spatial variations in the ocean. The diel changes in surface OCS first reported by Ferek and Andreae (1984) led those workers to suggest a photochemical production mechanism. Additions of dissolved organic sulfur compounds such as dimethylsulfoniopropionate (DMSP), dimethyl sulfoxide, dimethyl sulfide, methionine, cysteine, and glutathione show that the organic sulfides, particularly glutathione, have the greatest yields of OCS during irradiation (Ferek and Andreae 1984;Zepp and Andreae 1994; Flöck et al. 1997). Studies of the wavelength dependence of OCS photoproduction (apparent quantum yields) in coastal (Zepp 1 Present address: Virginia Institute of Marine Science, P.O. Box 1346, Gloucester Point, Virginia 23062. AcknowledgmentsWe thank Ollie Zafiriou for serving as the chief scientist and catalyst for these cruises, Alison Featherstone for...

show abstract

Section: Resultsmentioning

confidence: 70%

Sources and cycling of carbonyl sulfide in the Sargasso Sea

Cutter

Filippino

2004

Limnology & Oceanography

View full text Add to dashboard Cite

show abstract

“…CDOM is quantified as the absorption coefficient at 325 nm of the dissolved materials as determined using a WPI UltraPath liquid waveguide spectrophotometer [Miller et al, 2002] following procedures developed for this study [Nelson et al, 2007;Swan et al, 2009]. Samples were collected from Niskin bottles and were filtered using 0.2 mm Nuclepore polycarbonate filters that had been rinsed with ultrapure water [Nelson et al, 1998]. Absorption spectra of the filtered seawater samples were recorded against ultrapure water (prepared using a Barnstead Nanopure Diamond UV) in the 1.984 m liquid waveguide spectrophotometer.…”

Section: Methodsmentioning

confidence: 99%

Tracing global biogeochemical cycles and meridional overturning circulation using chromophoric dissolved organic matter

Nelson

Siegel

Carlson

et al. 2010

Geophysical Research Letters

144

142

View full text Add to dashboard Cite

[1] Basin-scale distributions of light absorption by chromophoric dissolved organic matter (CDOM) are positively correlated (R 2 > 0.8) with apparent oxygen utilization (AOU) within the top kilometer of the Pacific and Indian Oceans. However, a much weaker correspondence is found for the Atlantic (R 2 < 0.05). Strong correlation between CDOM and AOU indicates that CDOM is created as a byproduct of the oxidation of organic matter from sinking particles. The observed meridional-depth sections of CDOM result from a balance between biogeochemical processes (autochthonous production and solar bleaching) and the meridional overturning circulation. Rapid mixing in the Atlantic dilutes CDOM in the interior and implies that the time scale for CDOM accumulation is greater than ∼50 years. CDOM emerges as a unique tracer for diagnosing changes in biogeochemistry and the overturning circulation, similar to dissolved oxygen, with the additional feature that it can be quantified from satellite observation.

show abstract

“…The results from the ANOVA tests show that there are seasonal fluctuations in CDOM abundance with the lowest values found in winter. The fact that the mean a 375 and a values are highest both in the surface * 375 (photic) waters and during summertime suggests that CDOM is closely linked to in situ productivity in these waters (Nelson et al 1998). The higher a values indicate the presence * 375 of more recently produced CDOM with a relatively more intense color.…”

Section: ϫ64a375mentioning

confidence: 99%

The optics of chromophoric dissolved organic matter (CDOM) in the Greenland Sea: An algorithm for differentiation between marine and terrestrially derived organic matter

Stedmon¹,

Markager²

2001

Limnology & Oceanography

194

156

View full text Add to dashboard Cite

The optics of chromophoric dissolved organic matter (CDOM) in the Greenland Sea were investigated and compared to results from earlier studies in the Southeastern North Sea. Absorption at 375 nm (a375) in the Greenland Sea varied from 0.77 m−1 to the detection limit of our instrument (0.05 m−1), with the highest values found during summer. The spectral slope coefficient (S) ranged from 8.2 to 26.4 µm−1 with the highest values occurring during winter. Seasonal variations in the in situ production and degradation of CDOM where shown to be responsible for the trends seen. A negative correlation between S and a375 was evident in the Greenland Sea and differed noticeably from that found in coastal waters. The differing S‐a375 behavior of CDOM known to be of terrestrial origin allowed the development of an algorithm for the differentiation between marine and terrestrial organic matter. The behavior of marine CDOM was modeled by S = 7.4 + 1.1/a375.

show abstract

Seasonal dynamics of colored dissolved material in the Sargasso Sea

Cited by 357 publications

References 52 publications

Sources and cycling of carbonyl sulfide in the Sargasso Sea

Sources and cycling of carbonyl sulfide in the Sargasso Sea

Tracing global biogeochemical cycles and meridional overturning circulation using chromophoric dissolved organic matter

The optics of chromophoric dissolved organic matter (CDOM) in the Greenland Sea: An algorithm for differentiation between marine and terrestrially derived organic matter

Contact Info

Product

Resources

About