Dissolved Organic Matter Dynamics in the Epipelagic Northwest Pacific Low‐Latitude Western Boundary Current System: Insights From Optical Analyses

Wang, Chao; Li, Yizhen; Li, Yan; Zou, Hui; Stubbins, Aron; Dahlgren, Randy A.; Wang, Zhiheng; Guo, Weidong

doi:10.1029/2021jc017458

Cited by 20 publications

(25 citation statements)

References 65 publications

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“…Similar fluorescence signatures were previously categorized to represent a mixture of humic-like peak A and marine humic-like peak M (Coble, 1996). C1 presented 56 pairs of matches in the online comparison, including components found in various aquatic environments, such as seawater (Kowalczuk et al, 2013;Catalá et al, 2015), river and estuarine waters (Guo et al, 2011), and groundwater (Wang et al, 2013;Yang et al, 2015), which were tightly related to in situ microbial activities (Wang et al, 2021). C2 displayed two excitation maxima at 250 and 340 nm and one emission maxima at 448 nm.…”

Section: Parafac Resultssupporting

confidence: 57%

“…C3 had an excitation/emission maximum at 270/ 460 nm, which was similar to common humic-like peak A. Matches for C2 and C3 were found in seven and four published models, respectively. However, these components are ubiquitously found in aquatic DOM from watershed to deep ocean continuum (Wang et al, 2013(Wang et al, , 2021Qu et al, 2022). C4 had excitation/emission maxima at ≤ 240 and 275 nm/340 nm, which is consistent with tryptophan-like peak T (Coble, 1996).…”

Section: Parafac Resultsmentioning

confidence: 85%

“…DOC concentrations of 15 groundwater and river water samples were measured in triplicate using an Elementar Vario TOC cube (Germany) in high-temperature catalytic oxidation mode with the coefficients of variance <2% (Wang et al, 2021). A five-point standard curve was generated using potassium hydrogen phthalate standards.…”

Section: Dissolved Organic Carbon Analysismentioning

confidence: 99%

“…Absorption and fluorescence spectroscopies are effective techniques for tracing DOM transport from the watershed to the open ocean (Baker, 2001;Guo et al, 2014;Li et al, 2019;Wang et al, 2021;Qu et al, 2022). They are thus widely used to characterize the sources, levels, composition, and flux of colored and fluorescent DOM (CDOM and FDOM) in groundwater (Chen et al, 2010;Tedetti et al, 2011;Nelson et al, 2015;Kim and Kim, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Sources, spectral characteristics, and fluxes of dissolved organic matter in coastal groundwater and river water in western Guangdong, China

Wang

Hu²,

Liu³

et al. 2022

Front. Environ. Sci.

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Groundwater discharge and river runoff are two important ways for allochthonous dissolved organic matter (DOM) to enter the ocean, but they vary spatially. Currently, the source, composition, and efflux of groundwater and riverine dissolved organic matter to the tropical northern South China Sea remain poorly understood, preventing an accurate estimate of coastal carbon budgets. In July 2021, nine groundwater and six river water samples were collected along the coast of western Guangdong and were characterized using dissolved organic carbon (DOC) analysis, UV-visible, and fluorescence spectroscopy techniques. Atypical absorption spectra were strongly observed in groundwaters, which were mainly attributed to the high-level nitrates. An exponential-Gaussian equation showed that the average contribution of nitrate to total groundwater absorbances was up to 36% at ∼ 300 nm. Groundwater showed lower levels of DOC, colored dissolved organic matter (CDOM), and fluorescent dissolved organic matter (FDOM) as compared to river water, whereas the humic-like components dominated both groundwater and river water FDOM pools. Higher values of spectral slope S350–400, fluorescence index, biological index, and the ratio of two humic-like fluorescence jointly reveal that groundwater DOM mainly originated from microbial activities, whereas the river water DOM had considerable contribution from terrestrial soil. High precipitation, natural or agricultural land types, and a lack of seawater intrusion are expected to cause low levels of groundwater DOM in western Guangdong. Among 52 rivers from across the globe, high watershed productivity and precipitation may lead to high–moderate DOM levels in river water in western Guangdong. The DOM fluxes via fresh groundwater discharge in western Guangdong are comparable in magnitude to those by river runoff, accounting for 16%–18% of the Pearl River DOM fluxes. Based on the slopes of linear correlations between CDOM and DOC obtained in groundwater samples and 52 rivers, as well as the data on water fluxes and DOC levels, the global CDOM fluxes via groundwater discharge and river runoff are estimated to be 3.5–12.2 × 1012 m2 yr−1 and 4.3 ± 0.3 × 1014 m2 yr−1, respectively, highlighting the importance of considering groundwater discharge and river runoff in coastal carbon budgets.

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Section: Parafac Resultssupporting

confidence: 57%

Section: Parafac Resultsmentioning

confidence: 85%

Section: Dissolved Organic Carbon Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sources, spectral characteristics, and fluxes of dissolved organic matter in coastal groundwater and river water in western Guangdong, China

Wang

Hu²,

Liu³

et al. 2022

Front. Environ. Sci.

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“…Fluorescence excitation-emission matrices (emission scan: 280-600 nm, excitation scan: 240-450 nm) normalized to Raman Units (RU) were measured using a Varian Cary Eclipse spectrofluorometer (Agilent, USA) for May-June 2016 samples and a F-7100 spectrofluorometer (Hitachi, Japan) for June-July 2018 samples (Wang et al, 2017). The ubiquitous two humic-like (peak A, ex/em: 260/456 nm, and peak M, ex/em: 320/400 nm) and one protein-like component (peak T, ex/em: 275/340 nm) were determined in this study (Coble, 1996;Wang et al, 2021) (Figure S2). The coefficients of variation for RU-normalized fluorescent intensities of the three peaks between the two spectrofluorometers for 5 samples collected during July 2018 cruise were <4%.…”

Section: Dark South China Sea (Scs)mentioning

confidence: 99%

Temperature‐Regulated Turnover of Chromophoric Dissolved Organic Matter in Global Dark Marginal Basins

Wang

Guo

et al. 2021

Geophysical Research Letters

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Marine dissolved organic matter (DOM) in the dark ocean (>200 m) contains a large refractory DOM (RDOM) pool (∼615 Pg carbon) similar in magnitude to the atmospheric CO 2 -C pool (Hansell, 2013). The RDOM pool is primarily formed during heterotrophic degradation of labile organic matter, which has a pronounced sensitivity to temperature (Brewer & Peltzer, 2017;Jiao et al., 2010;Shen & Benner, 2020). Since the 1960s, the ocean has exhibited an accelerated warming at all depths, with a discernable temperature increase in the global dark ocean (Cheng et al., 2017;Levitus et al., 2012). Thus, determining the temperature effect on microbial regulation of the oceanic RDOM pool is essential as its carbon exchange with the atmosphere is a potentially sensitive feedback mechanism to global climate change (Lønborg et al., 2020). However, detailed knowledge concerning the temperature sensitivity of the RDOM pool is still lacking (Lønborg et al., 2018).The semi-enclosed nature and distinctive geomorphology of dark marginal basins create unique ventilation and circulation patterns relative to the open ocean interior that strongly alter the export flux of degradable organic matter and oxygen utilization (

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Molecular level characterization of DOM along a freshwater-to-estuarine coastal gradient in the Florida Everglades

et al. 2022

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Dissolved Organic Matter Dynamics in the Epipelagic Northwest Pacific Low‐Latitude Western Boundary Current System: Insights From Optical Analyses

Cited by 20 publications

References 65 publications

Sources, spectral characteristics, and fluxes of dissolved organic matter in coastal groundwater and river water in western Guangdong, China

Sources, spectral characteristics, and fluxes of dissolved organic matter in coastal groundwater and river water in western Guangdong, China

Temperature‐Regulated Turnover of Chromophoric Dissolved Organic Matter in Global Dark Marginal Basins

Molecular level characterization of DOM along a freshwater-to-estuarine coastal gradient in the Florida Everglades

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