Changes in dissolved organic matter composition and dynamics in a subtropical mangrove river driven by rainfall

Kida, Morimaru; Tanabe, Mai; Tomotsune, Mitsutoshi; Yoshitake, Shinpei; Kinjo, Kazutoshi; Ohtsuka, Toshiyuki

doi:10.1016/j.ecss.2019.04.029

Cited by 32 publications

(24 citation statements)

References 64 publications

(125 reference statements)

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“…As for DOC, we previously investigated the dynamics of fluorescent dissolved organic matter (DOM) through excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC) for 2 years [22]. The EEM-derived biological index, an indicator of freshly produced DOM by microbes, lacked evidence of newly produced DOM inputs within the forest [22]. Water within the mangrove forest was more turbid than headwater and seawater, which precluded possible phytoplankton-derived DOC inputs within the forest.…”

Section: Methods For Dissolved Carbon Export Estimatesmentioning

confidence: 99%

“…Furthermore, Ishigaki Island is subjected to typhoons every year, and typhoons are another significant factor that increases water discharge in mangrove forests. Kida et al [22] observed a sharp increase in DOC concentration due to heavy rain with typhoons in the Fukido River. More methods are required to estimate annual lateral fluxes while considering the lunar cycle and episodic events such as typhoons.…”

Section: Dissolved Carbon Flux With Tidal Amplitudementioning

confidence: 96%

“…If outwelling C is derived from outside of mangrove forests, lateral C exports from the mangrove estuary do not directly contribute to the C budget of mangrove NEP. River water discharge in Fukido mangrove is less than 10% of tidal water exchange, and DOC concentrations of the upper Fukido River are low compared with the other mangrove forests [22]. However, we did not measure the exchange of POC or litter fluxes in the river.…”

Section: Mangrove Carbon Budget and Lateral C Fluxesmentioning

confidence: 97%

“…The Fukido River is short (<1.5 km), and the area of the watershed is 2.57 km 2 , including the mangrove estuary (19 ha), which occurs around the river mouth. Natural subtropical evergreen broad-leaved forests (or lucidophyllous forests) occupy~95% of the watershed, with the rest of land use being sparse sugarcane and paddy fields (0.11 km 2 ) [22]. There are only two mangrove species in the estuary: Bruguiera gymnorrhiza and Rhizophora stylosa.…”

Section: Study Sitementioning

confidence: 99%

“…The carbon contamination from the filter was negligible (<0.01 mg C L −1 ) according to this protocol. The DOC was measured as non-purgeable organic carbon in a total organic carbon analyzer (TOC-L CPH , Shimadzu, Japan) using the platinum-catalyzed high-temperature combustion method coupled to non-dispersive infrared gas detection of CO 2 [22]. We sprayed the samples with CO 2 -free carrier gas for 90 s in the built-in syringe of the TOC analyzer to remove any DIC prior to combustion after acidification.…”

Section: Water Sampling and Analysismentioning

confidence: 99%

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Lateral Export of Dissolved Inorganic and Organic Carbon from a Small Mangrove Estuary with Tidal Fluctuation

Ohtsuka

Onishi

Yoshitake

et al. 2020

Forests

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The significance of aquatic lateral carbon (C) export in mangrove ecosystems highlights the extensive contribution of aquatic pathways to the net ecosystem carbon budget. However, few studies have investigated lateral fluxes of dissolved organic carbon (DOC) and inorganic carbon (DIC), partly due to methodological difficulty. Therefore, we evaluated area-based lateral C fluxes in a small mangrove estuary that only had one exit for water exchange to the coast. We sampled water from the mouth of the creek and integrated discharge and consecutive concentration of mangrove-derived C (ΔC). Then, we estimated the area-normalized C fluxes based on the inundated mangrove area. DIC and DOC concentrations at the river mouth increased during ebb tide during both summer and winter. We quantified the ΔC in the estuary using a two-component conservative mixing model of freshwater and seawater. DIC and DOC proportions of ΔC concentrations at the river mouth during ebb tide was between 34% and 56% in the winter and 26% and 42% in the summer, respectively. DIC and DOC fluxes from the estuary were estimated to be 1.36 g C m−2 d−1 and 0.20 g C m−2 d−1 in the winter and 3.35 g C m−2 d−1 and 0.86 g C m−2 d−1 in the summer, respectively. Based on our method, daily fluxes are mangrove area-based DIC and DOC lateral exports that can be directly incorporated into the mangrove carbon budget.

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Section: Methods For Dissolved Carbon Export Estimatesmentioning

confidence: 99%

Section: Dissolved Carbon Flux With Tidal Amplitudementioning

confidence: 96%

Section: Mangrove Carbon Budget and Lateral C Fluxesmentioning

confidence: 97%

Section: Study Sitementioning

confidence: 99%

Section: Water Sampling and Analysismentioning

confidence: 99%

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