Controls on the production of organohalogens by phytoplankton: Effect of nitrate concentration and grazing

Smythe-Wright, Denise; Peckett, Cristina; Boswell, Stephen M.; Harrison, R M

doi:10.1029/2009jg001036

Cited by 12 publications

(4 citation statements)

References 67 publications

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“…Thus we suggest that photochemistry and biological production likely both played a role during MSM18/3. Haptophytes correlated most significantly of the phytoplankton groups with CH 3 I and have already been shown to produce CH 3 I both in the laboratory (Itoh et al, 1997;Manley and de la Cuesta, 1997;Scarratt and Moore, 1998;Smythe-Wright et al, 2010) and in the field (Abrahamsson et al, 2004b). Correlations during MSM18/3 additionally indicate a possible involvement of dinoflagellates and chrysophytes in the production of methyl iodide ( Table 2).…”

Section: Ch 3 I and Ch 2 Imentioning

confidence: 82%

Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

et al. 2015

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Abstract.Halocarbons from oceanic sources contribute to halogens in the troposphere, and can be transported into the stratosphere where they take part in ozone depletion. This paper presents distribution and sources in the equatorial Atlantic from June and July 2011 of the four compounds bromoform (CHBr 3 ), dibromomethane (CH 2 Br 2 ), methyl iodide (CH 3 I) and diiodomethane (CH 2 I 2 ). Enhanced biological production during the Atlantic Cold Tongue (ACT) season, indicated by phytoplankton pigment concentrations, led to elevated concentrations of CHBr 3 of up to 44.7 and up to 9.2 pmol L −1 for CH 2 Br 2 in surface water, which is comparable to other tropical upwelling systems. While both compounds correlated very well with each other in the surface water, CH 2 Br 2 was often more elevated in greater depth than CHBr 3 , which showed maxima in the vicinity of the deep chlorophyll maximum. The deeper maximum of CH 2 Br 2 indicates an additional source in comparison to CHBr 3 or a slower degradation of CH 2 Br 2 . Concentrations of CH 3 I of up to 12.8 pmol L −1 in the surface water were measured. In contrary to expectations of a predominantly photochemical source in the tropical ocean, its distribution was mostly in agreement with biological parameters, indicating a biological source. CH 2 I 2 was very low in the near surface water with maximum concentrations of only 3.7 pmol L −1 . CH 2 I 2 showed distinct maxima in deeper waters similar to CH 2 Br 2 . For the first time, diapycnal fluxes of the four halocarbons from the upper thermocline into and out of the mixed layer were determined. These fluxes were low in comparison to the halocarbon sea-to-air fluxes. This indicates that despite the observed maximum concentrations at depth, production in the surface mixed layer is the main oceanic source for all four compounds and one of the main driving factors of their emissions into the atmosphere in the ACTregion. The calculated production rates of the compounds in the mixed layer are 34 ± 65 pmol m −3 h −1 for CHBr 3 , 10 ± 12 pmol m −3 h −1 for CH 2 Br 2 , 21 ± 24 pmol m −3 h −1 for CH 3 I and 384 ± 318 pmol m −3 h −1 for CH 2 I 2 determined from 13 depth profiles.

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Section: Ch 3 I and Ch 2 Imentioning

confidence: 82%

Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

et al. 2015

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“…Marine CH 3 I is the most abundant organoiodine in the troposphere, while the very short-lived CH 2 I 2 and CH 2 ClI contribute potentially as much organic iodine (Saiz-Lopez et al, 2012). Significant amounts of halocarbons and their degradation products can be carried into the stratosphere (Solomon et al, 1994;Hossaini et al, 2010;Aschmann et al, 2011), especially in the tropical regions where surface air can be transported very rapidly into the tropical tropopause layer by tropical deep convection (Tegtmeier et al, 2012;Tegtmeier et al, 2013). The short-lived brominated and iodinated halocarbons produced in the equatorial region may hence play an important role for stratospheric halogens.…”

Section: Introductionmentioning

confidence: 99%

Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

Hepach¹,

Quack²,

Raimund³

et al. 2015

Preprint

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Abstract. Halocarbons from oceanic sources contribute to halogens in the troposphere, and can be transported into the stratosphere where they take part in ozone depletion. This paper presents distribution and sources in the equatorial Atlantic from June and July 2011 of the four compounds bromoform (CHBr3), dibromomethane (CH2Br2), methyl iodide (CH3I) and diiodomethane (CH2I2). Enhanced biological production during the Atlantic Cold Tongue (ACT) season, indicated by phytoplankton pigment concentrations, led to elevated concentrations of CHBr3 of up to 44.7 pmol L−1 and up to 9.2 pmol L−1 for CH2Br2 in surface water, which is comparable to other tropical upwelling systems. While both compounds correlated very well with each other in the surface water,CH2Br2 was often more elevated in greater depth than CHBr3, which showed maxima in the vicinity of the deep chlorophyll maximum. The deeper maximum of CH2Br2 indicates an additional source in comparison to CHBr3 or a slower degradation of CH2Br2. Concentrations of CH3I of up to 12.8 pmol L−1 in the surface water were measured. In contrary to expectations of a predominantly photochemical source in the tropical ocean, its distribution was mostly in agreement with biological parameters, indicating a~biological source. CH2I2 was very low in the near surface water with maximum concentrations of only 3.7 pmol L−1, and the observed anticorrelation with global radiation was likely due to its strong photolysis. CH2I2 showed distinct maxima in deeper waters similar to CH2Br2. For the first time, diapycnal fluxes of the four halocarbons from the upper thermocline into and out of the mixed layer were determined. These fluxes were low in comparison to the halocarbon sea-to-air fluxes. This indicates that despite the observed maximum concentrations at depth, production in the surface mixed layer is the main oceanic source for all four compounds and has an influence on emissions into the atmosphere. The calculated production rates of the compounds yield 34 (CHBr3), 10 (CH2Br2), 21 (CH3I) and 384 (CH2I2) pmol m−3 h−1 in the whole mixed layer.

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“…The temporal developments in the concentrations of Chl-a, DMS, DMSP, and DMSO in each treatment are presented in Figure 3. Previous studies have shown that Chl-a concentrations generally follow the same pattern as algal cell growth (Lim et al, 2018;Smythe-Wright et al, 2010), therefore Chl-a can be considered a representative index for the density of phytoplankton. As shown in Figure 3a, the growth patterns of the phytoplankton in different treatments were similar and all exhibited a "unimodal" pattern, with their maximum values appearing on days 7-9.…”

Section: Chl-amentioning

confidence: 97%

Effects of Phytoplankton on the Production and Emission of Estuarine Dimethyl Sulfide Under Different Nutrient Inputs From Changjiang River

et al. 2022

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Continuous input from the Changjiang River significantly reshuffled the ecosystems in the Changjiang Estuary and adjacent East China Sea, impacting the production, distribution, and emission of marine dimethyl sulfide (DMS). However, the effect of phytoplankton biomass and composition on DMS under different nutrient inputs remains poorly understood. Two comprehensive cruises to characterize their effects were conducted in spring and summer 2015. The areas with high concentrations of DMS, dimethylsulfoniopropionate (precursor of DMS), and dimethyl sulfoxide (photo‐oxidation product of DMS) were largely consistent with high phytoplankton abundances along the front of Changjiang Diluted Water in both seasons. Both the higher conversion ratio of dissolved dimethylsulfoniopropionate to DMS and the higher DMS biological production rate in summer contributed to the higher DMS levels. Once produced in seawater, more than half of the DMS was directly consumed by microbes, resulting in a turnover time of 1–2 days, which was shorter than that driven by ventilation. A ship‐based incubation experiment revealed that, with increasing N/Si and N/P ratios from the Changjiang River, phytoplankton biomass increased and the community shifted from diatom‐dominated to dinoflagellate‐dominated, which was conducive to DMS production. It was noteworthy that strong DMS photo‐degradation induced by high nitrate concentrations may have masked DMS production to some extent, while urea only had a promoting effect and therefore led to a maximum increase in DMS yield. Our findings indicated that the increase in phytoplankton biomass and succession of phytoplankton community induced by changes in nutrient inputs will promote DMS emissions from the Changjiang Estuary.

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Controls on the production of organohalogens by phytoplankton: Effect of nitrate concentration and grazing

Cited by 12 publications

References 67 publications

Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

Effects of Phytoplankton on the Production and Emission of Estuarine Dimethyl Sulfide Under Different Nutrient Inputs From Changjiang River

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