A large artificial dyke greatly alters partitioning of sulfate and iron reduction and resultant phosphorus dynamics in sediments of the Yeongsan River estuary, Yellow Sea

An, Sung‐Uk; Mok, Jin-Sook; Kim, Sung-Han; Choi, Jin Seek; Hyun, Jung‐Ho

doi:10.1016/j.scitotenv.2019.02.058

Cited by 20 publications

(13 citation statements)

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“…This result implies that the target interval of the YAR-4 sediments experienced considerable early reductive diagenesis under anoxic conditions, causing considerable dissolution of detrital magnetic minerals. It is apparently in agreement with the current anoxic conditions at depths below 0.03 m, where methane concentrations are higher, at a site in Yeongsan Lake (An et al, 2019). This suggestion is also consistent with the widespread presence of the middle-coercivity component (component 2 in Figure 8), i.e., greigite (see Magnetic Mineralogy and Granulometry from Magnetic Measurements and FIGURE 9 | Biplot of IRM 1T /χ lf vs. B cr for the YAR-4 core sediments (red circles; n 11), with typical ranges (gray boxes) of the magnetic parameters for different minerals proposed by Peters and Thompson (1998) and data for the A5 sediments reported by Nilsson et al (2013) (black squares).…”

Section: Diagenetic Effects On Downcore Variation In Magnetic Propertiessupporting

confidence: 88%

“…Unfortunately, our analyzed subsamples were not weighed, thereby not permitting to determine accurately χ values for the same subsamples. Nevertheless, the χ values could be approximated by converting the aforementioned volume-specific susceptibility (k) values, using a mean density of 1.17 g/cm 3 and a mean water content of 71.3 wt% for wet surface sediments in the Yeongsan Lake (An et al, 2019). Assuming the water density of 1.00 g/cm 3 and that the porosity of the studied sediments (silt-dominant, shallow depths) was little varied through the whole core (i.e., negligible porosity variation for shallow depths; e.g., Bahr et al, 2001), a mean value in dry density of the studied sediment samples could be approximated to 2.03 g/cm 3 (considered as a maximal value).…”

Section: Downcore Variation In Magnetic Propertiesmentioning

confidence: 99%

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Magnetic Properties of a Holocene Sediment Core from the Yeongsan Estuary, Southwest Korea: Implications for Diagenetic Effects and Availability as Paleoenvironmental Proxies

Ahn¹,

Lim

Kim

2021

Front. Earth Sci.

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The sensitivity of magnetic properties, which characterize the mineralogy, concentration, and grain size distribution of magnetic minerals, to environmental processes may provide useful information on paleoenvironmental changes in estuarine environments. Magnetic property studies of estuaries are less common than other environments and, due to the west coast of South Korea having an abundance of estuaries, it provides a good place to study these processes. In this study, we analyzed a variety of magnetic properties based on magnetic susceptibility, hysteresis parameters, progressive acquisition of isothermal remanent magnetization and first-order reversal curve data from a Holocene muddy sediment core recovered from the Yeongsan Estuary on the west coast of South Korea. We examined diagenetic effects on magnetic properties and tested their availability as proxies of paleoenvironmental change. The presence of generally low magnetic susceptibility, ubiquitous greigite-like authigenic magnetic component, and very fine magnetic particle occurrence suggested that the analyzed sediments had undergone considerable early diagenetic alteration. Electron microscopic observations of magnetic minerals support this suggestion. Our results confirm that the use of initial bulk susceptibility as a stand-alone environmental change proxy is not recommended unless it is supported by additional magnetic analyses. We recognized the existence of ferromagnetic-based variabilities related to something besides the adverse diagenetic effects, and have examined possible relationships with sea-level and major climate changes during the Holocene. The most remarkable finding of this study is the two distinct intervals with high values in magnetic coercivity (Bc), coercivity of remanence (Bcr), and ratio of remanent saturation moment to saturation moment (Mrs/Ms) that were well coincident with the respective abrupt decelerations in the rate of sea-level rise occurred at around 8.2 and 7 thousand years ago. It is then inferred that such condition with abrupt drop in sea-level rise rate would be favorable for the abrupt modification of grain size distribution toward more single-domain-like content. We modestly propose consideration of the Bc, Bcr, and Mrs/Ms variability as a potential indicator for the initiation/occurrence of sea-level stillstand/slowstand or highstand during the Holocence, at least at estuarine environments in and around the studied area.

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Section: Diagenetic Effects On Downcore Variation In Magnetic Propertiessupporting

confidence: 88%

Section: Downcore Variation In Magnetic Propertiesmentioning

confidence: 99%

Magnetic Properties of a Holocene Sediment Core from the Yeongsan Estuary, Southwest Korea: Implications for Diagenetic Effects and Availability as Paleoenvironmental Proxies

Ahn¹,

Lim

Kim

2021

Front. Earth Sci.

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“…The rates and pathways of C org oxidation in sediments are largely regulated by the availability of electron donors (i.e., labile organic matters) and acceptors (Canfield et al, 2005). In coastal sediments, various physico-chemical and biological factors such as vegetation, bioturbation, freshwater runoff, tidal inundation, and anthropogenic activities are responsible for availability of the electron donors and acceptors for microbial metabolic activities (Alongi et al, 1999;Kristensen and Kostka, 2005;Hyun et al, 2009;An et al, 2019;Mok et al, 2019). Of all the environmental factors, marsh plants significantly affect biogeochemical properties by translocating organic matter via roots and rhizomes (Armstrong et al, 2000;Lee, 2003;Sundby et al, 2003;Koop-Jakobsen et al, 2018).…”

Section: Influence Of Invasive S Anglica On C Org Oxidationmentioning

confidence: 99%

“…However, in coastal areas where rapid iron cycling occurs, microbial Fe(III) reduction (FeR) becomes a significant anaerobic C org oxidation pathway (Kostka et al, 2002a,b;Jensen et al, 2003;Hyun et al, 2007Hyun et al, , 2009Kristensen et al, 2011). Because of the abundance and highly reactive properties of iron and sulfur in marine sediments, the partitioning of C org oxidation by FeR and SR has a profound influence on the distribution and behavior of redox-sensitive metals and nutrients (Jensen et al, 1995;Dollhopf et al, 2005;Quintana et al, 2015;An et al, 2019;Mok et al, 2019). Therefore, elucidation of the relative significance of FeR and SR in C org oxidation can improve our understanding of biogeochemical processes in sediments (King et al, 2001;Koretsky et al, 2003;Hyun et al, 2009;Luo et al, 2016;An et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Invasive Spartina anglica Greatly Alters the Rates and Pathways of Organic Carbon Oxidation and Associated Microbial Communities in an Intertidal Wetland of the Han River Estuary, Yellow Sea

Cho

Jung

et al. 2020

Front. Mar. Sci.

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Biogeochemical process studies and molecular microbiological analyses were applied to assess the effect of invasive Spartina anglica (SA) on organic carbon (C org ) oxidation pathways and microbial community structures in intertidal sediments vegetated by the indigenous marsh plant Suaeda japonica (SJ) and unvegetated mud flats (UMF). Invasive S. anglica possessed 10 times the below-ground biomass of native S. japonica, which was responsible for releasing a substantial amount of labile dissolved organic matter and creating relatively oxidized conditions at the SA site. As a result, microbial metabolic activities measured by rates of anaerobic C org oxidation, iron reduction (FeR) and sulfate reduction (SR) appeared to be greater at SA site compared with the SJ and UMF sites. SR was the dominant anaerobic respiration pathway at a depth of 0-10 cm for vegetated sediments, but the contribution of FeR to C org oxidation was exceptionally high in the rhizosphere of the vegetated sites, comprising 60% and 70% of anaerobic C org oxidation of SA and SJ, respectively. The iron turnover rate at the rhizosphere was 3 times higher at SA site (0.063 d −1 ) compared with the SJ site (0.023 d −1 ), indicating that the denser root system of invasive S. anglica greatly accelerates iron cycling. Bacterial communities based on 16S rRNA genes analysis revealed that members in Desulfuromonadaceae related to the reduction of FeOOH and S 0 were highly abundant at the relatively oxidized SA site, whereas Desulfobulbaceae, which are known as sulfate reducers, were more dominant at the relatively reduced SJ site. Similarly, two sulfur-oxidizing bacteria groups with different eco-physiological strategies thrived in each of the two vegetated sites. Thioprofundaceae in the Gammaproteobacteria were the predominant S-oxidizers at the less-reduced SA site, whereas Sulfurovum in the Epsilonproteobacteria dominated at the relatively reduced SJ site. Our results suggest that an invasion of tall S. anglica and its subsequent displacement of native S. japonica would greatly alter the biogeochemical C-Fe-S cycles and associated microbial communities, which ultimately generate multidirectional variations in ecological and biogeochemical processes in coastal ecosystems.

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“…Phosphorus (P) is a key nutrient, not only regulating primary production as a limiting nutrient in aquatic ecosystems, but also inducing eutrophication that can stimulate undesirable algal blooms in coastal ecosystems (Tyrrell, 1999;Diaz and Rosenberg, 2008;Middelburg and Levin, 2009;Lomnitz et al, 2016). In shallow coastal ecosystems, sediment serves either as a source (i.e., regeneration and release) or a sink (i.e., adsorption and precipitation) of P for the water column (Slomp, 2011;Kraal et al, 2015;An et al, 2019). P dynamics in coastal sediments are tightly coupled to the rate and partitioning of C org mineralization and the resulting interaction between iron and sulfur (Rozan et al, 2002;Canfield et al, 2005;Kraal et al, 2013;Slomp et al, 2013;Andrieux-Loyer et al, 2014;An et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Phosphorus Dynamics Associated With Organic Carbon Mineralization by Reduction of Sulfate and Iron in Sediment Exposed to Fish Farming

et al. 2021

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The expansion of the aquaculture industry has resulted in accumulation of phosphorus (P)-rich organic matter via uneaten fish feed. To elucidate the impact of fish farming on P dynamics, P speciation, and benthic P release along with partitioning of organic carbon (Corg) mineralization coupled to sulfate reduction (SR) and iron reduction (FeR) were investigated in the sediments from Jinju Bay, off the southern coast of South Korea, in July 2013. SR in the farm sediment was 6.9-fold higher than the control sediment, and depth-integrated (0–10 cm) concentrations of NH4+, PO43–, and H2S in pore water of the farm sediment were 2.2-, 3.3-, and 7.4-fold higher than that in control sediment, respectively. High biogenic-P that comprised 28% of total P directly reflected the impact of P-rich fish feed, which ultimately enhanced the bioavailability (58% of total P) of P in the surface sediment of the farm site. In the farm sediment where SR dominated Corg mineralization, H2S oxidation coupled to the reduction of FeOOH stimulated release of P bound to iron oxide, which resulted in high regeneration efficiency (85%) of P in farm sediments. Enhanced P desorption from FeOOH was responsible for the increase in authigenic-P and benthic P flux. Authigenic-P comprised 33% of total P, and benthic P flux to the overlying water column accounted for approximately 800% of the P required for primary production. Consequently, excessive benthic P release resulting directly from oversupply of P-rich fish feed was a significant internal source of P for the water column, and may induce undesirable eutrophication and harmful algal blooms in shallow coastal ecosystems.

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A large artificial dyke greatly alters partitioning of sulfate and iron reduction and resultant phosphorus dynamics in sediments of the Yeongsan River estuary, Yellow Sea

Cited by 20 publications

References 51 publications

Magnetic Properties of a Holocene Sediment Core from the Yeongsan Estuary, Southwest Korea: Implications for Diagenetic Effects and Availability as Paleoenvironmental Proxies

Magnetic Properties of a Holocene Sediment Core from the Yeongsan Estuary, Southwest Korea: Implications for Diagenetic Effects and Availability as Paleoenvironmental Proxies

Invasive Spartina anglica Greatly Alters the Rates and Pathways of Organic Carbon Oxidation and Associated Microbial Communities in an Intertidal Wetland of the Han River Estuary, Yellow Sea

Phosphorus Dynamics Associated With Organic Carbon Mineralization by Reduction of Sulfate and Iron in Sediment Exposed to Fish Farming

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