Very low salinity regions of estuaries: important sites for chemical and biological reactions

Morris, A.W.; Mantoura, R.F.C.; Bale, A.J.; Howland, R.J.M.

doi:10.1038/274678a0

Cited by 174 publications

(46 citation statements)

References 15 publications

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“…This increase of pCO 2 was mirrored by a general decrease of %O 2 , suggesting enhanced organic matter degradation in the oligohaline estuarine region, typical of estuarine environments (for example, Morris et al, 1978;Bianchi, 2006). In parallel, there was a general increase (Fig.…”

Section: Mixing Modelsmentioning

confidence: 94%

Carbon dynamics in the Mekong Delta

Borges

Abril

Bouillon

2017

Preprint

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We report a data-set obtained in the three branches (My Tho . The CO 2 emission to the atmosphere from the Mekong inner estuary was higher than reported in the Yangtze and Pearl River inner estuaries. This was probably due to the lower salinity in the Mekong delta branches, possibly due to different morphology; relatively linear channels in the Mekong delta versus funnel-15 shaped estuaries for the Yangtze and Pearl River inner estuaries.,Biogeosciences Discuss., https://doi

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Section: Mixing Modelsmentioning

confidence: 94%

Carbon dynamics in the Mekong Delta

Borges

Abril

Bouillon

2017

Preprint

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“…In April 2004, there was a marked increase in pCO 2 from the most upstream stations (salinity 0) to the stations located at 60 km from Vĩnh Long (corresponding roughly to a salinity of 2). This increase in pCO 2 was mirrored by a general decrease in %O 2 , suggesting en- hanced organic matter degradation in the oligohaline estuarine region, typical of estuarine environments (for example Morris et al, 1978;Bianchi, 2006). In parallel, there was a general increase in DSi from salinity 0 to 2 suggesting that part of the enhanced organic matter degradation in the upper estuary in April 2004 was fuelled by the decay of freshwater diatoms due to haline (osmotic) stress (for example Muylaert and Sabbe, 1999;Ragueneau et al, 2002), as also observed in other tropical estuaries such as the Tana and the Kidogoweni in Kenya (Bouillon et al, 2007a, b Meybeck and Carbonnel (1975) at Phnom Penh from January 1961 to 1962.…”

Section: Data Setmentioning

confidence: 96%

Carbon dynamics and CO<sub>2</sub> and CH<sub>4</sub> outgassing in the Mekong delta

2018

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Abstract. We report a data set of biogeochemical variables related to carbon cycling obtained in the three branches (M y Tho, Hàm Luông, Có Chiên) of the Mekong delta (Bén Tre province, Vietnam) in December 2003, April 2004, and October 2004. Both the inner estuary (upstream of the mouth) and the outer estuary (river plume) were sampled, as well as side channels. The values of the partial pressure of CO 2 (pCO 2 ) ranged between 232 and 4085 ppm, O 2 saturation level (%O 2 ) between 63 and 114 %, and CH 4 between 2 and 2217 nmol L −1 , within the ranges of values previously reported in temperate and tropical meso-and macro-tidal estuaries. Strong seasonal variations were observed. In the upper oligohaline estuary, low pCO 2 (479-753 ppm) and high %O 2 (98-106 %) values were observed in April 2004 most probably related to freshwater phytoplankton growth owing to low freshwater discharge (1400 m 3 s −1 ) and increase in water residence time; during the two other sampling periods with a higher freshwater discharge (9300-17 900 m 3 s −1 ), higher pCO 2 (1895-2664 ppm) and lower %O 2 (69-84 %) values were observed in the oligohaline part of the estuary. In October 2004, important phytoplankton growth occurred in the offshore part of the river plume as attested by changes in the contribution of particulate organic carbon (POC) to total suspended matter (TSM) (%POC) and the stable isotope composition of POC (δ 13 C-POC), possibly related to low TSM values (improvement of light conditions for phytoplankton development), leading to low pCO 2 (232 ppm) and high %O 2 (114 %) values. Water in the side channels in the Mekong delta was strongly impacted by inputs from the extensive shrimp farming ponds. The values of pCO 2 , CH 4 , %O 2 , and the stable isotope composition of dissolved inorganic carbon (δ 13 C-DIC) indicated intense organic matter degradation that was partly mediated by sulfate reduction in sediments, as revealed by the slope of total alkalinity (TA) and DIC covariations. The δ 13 C-POC variations also indicated intense phytoplankton growth in the side channels, presumably due to nutrient enrichment related to the shrimp farming ponds. A data set in the mangrove creeks of the Ca Mau province (part of the Mekong delta) was also acquired in April and October 2004. These data extended the range of variability in pCO 2 and %O 2 with more extreme values than in the Mekong delta (Bén Tre), with maxima and minima of 6912 ppm and 37 %, respectively. Similarly, the maximum CH 4 concentration (686 nmol L −1 ) was higher in the Ca Mau province mangrove creeks than in the Mekong delta (Bén Tre, maximum 222 nmol L −1 ) during the October 2004 cruise (rainy season and high freshwater discharge period). In April 2004 (dry season and low freshwater discharge period), the CH 4 values were much lower than in October 2004 (average 19 ± 13 and 210 ± 158 nmol L −1 , respectively) in the Ca Mau province mangrove creeks, owing to the higher salinity (average 33.2 ± 0.6 and 14.1 ± 1.2, respectively) that probably led to higher sedim...

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“…At the estuarine head, primary productivity increased as dissolved inorganic nutrients declined and seston increased. Others (Morris et al 1978, Filardo & Dunstan 1985 have ascribed the enhanced production at the freshwater-seawater interface to the prior death and mineralization of freshwater algae. We have found little evidence for this mechanism (Christian et al 1984) and consider it more likely that improved light conditions and extended residence tlme within the widened estuary promoted production (Boyer e t al.…”

Section: Overviewmentioning

confidence: 99%

Multi-year distribution patterns of nutrients within the Neuse River Estuary, North Carolina

Christian¹,

Boyer²,

Stanley³

1991

Mar. Ecol. Prog. Ser.

124

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Spabal and temporal patterns of nutnent dlstnbutions m the Neuse h v e r Estuary, North Carol~na were assessed from a 4 yr study lnvolvlng 82 longitudinal transects of the estuary T h s major nver-dominated estuary receives water from a 16 000 km2 dralnage basin and 1s connected to the Atlantic Ocean by Pamhco Sound Concentratlons of nltrogen and phosphorus species and chlorophyll a were measured in assoclabon u l t h environmental factors Intrastahon d~s t r l b u t~o n s of variables were generally non-normal and interstat~on dlstrlbutlon patterns vaned considerably between specles measured Concentrations of d~ssolved species decreased down-estuary although lnternal sources of both ammonlum and filterable reachve phosphorus were apparent Particulate specles demonstrated maxlma in the upper estuary associated with autochthonous production The relat~ve isolation of the Neuse k v e r Estualy from ocean inputs and long flushlng tlmes of freshwater provide an environment whlch promotes nonconservahve m w n g of nutrient species The average flushlng time for the estuary was 51 d providing an extended period w t h l n the estuary for substantial recycling Thus I s t n b u t l o n patterns reflect the dominance of biolog~cal and chemical achvlty except when large freshets cause r a p~d movement of water to the lower estuary and out Into Pamhco Sound

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Very low salinity regions of estuaries: important sites for chemical and biological reactions

Cited by 174 publications

References 15 publications

Carbon dynamics in the Mekong Delta

Carbon dynamics in the Mekong Delta

Carbon dynamics and CO<sub>2</sub> and CH<sub>4</sub> outgassing in the Mekong delta

Multi-year distribution patterns of nutrients within the Neuse River Estuary, North Carolina

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Very low salinity regions of estuaries: important sites for chemical and biological reactions

Cited by 174 publications

References 15 publications

Carbon dynamics in the Mekong Delta

Carbon dynamics in the Mekong Delta

Carbon dynamics and CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; outgassing in the Mekong delta

Multi-year distribution patterns of nutrients within the Neuse River Estuary, North Carolina

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Carbon dynamics and CO<sub>2</sub> and CH<sub>4</sub> outgassing in the Mekong delta