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Article ; Online: Holocene East Asian Summer Monsoon Rainfall Variability in Taiwan

Xiaodong Ding / Liwei Zheng / Xufeng Zheng / Shuh-Ji Kao

Frontiers in Earth Science, Vol

2020 Volume 8

Abstract: Characterizing the spatiotemporal variability of the East Asian summer monsoon (EASM) advances our understanding of its rhythm, dynamics, and future impacts. East Asian summer monsoon variations during the Holocene have been reconstructed from a variety ... ...

Abstract	Characterizing the spatiotemporal variability of the East Asian summer monsoon (EASM) advances our understanding of its rhythm, dynamics, and future impacts. East Asian summer monsoon variations during the Holocene have been reconstructed from a variety of geological archives and proxies. However, the spatiotemporal heterogeneity of EASM rainfall during the Holocene remains controversial. Taiwan is geographically suitable for studying the EASM history, through its geological archives. Herein, we synthesize the reported lake and peat sedimentary records of the entire Holocene, in addition to the records of mass-wasting and on-land deposition from cores collected from Taiwan to illustrate the EASM induced hydroclimate changes in Taiwan throughout the Holocene. Records from Taiwan indicate that the EASM rainfall maximum occurred during the early Holocene, concurring with other EASM records from monsoon regions in southern China. We suggest that the early Holocene EASM rainfall maximum in southern China was mainly forced by the higher Northern Hemisphere summer insolation and sea surface temperatures (SSTs) in the Western Pacific Warm Pool (WPWP). A synthesis of EASM rainfall records from across China shows that the timing of the Holocene EASM rainfall maximum occurred progressively later than that from southern to northern China. This time-transgressive EASM rainfall maximum may be due to the latitudinal shift of the westerlies and Western Pacific subtropical high (WPSH) that was induced by changes of interhemispheric temperature gradients (ΔTN–S) and the northern high latitude ice volume. Moreover, records from Taiwan suggest a significant collapse of the EASM in Taiwan at ∼4–2 ka BP. Based on the records from Taiwan, coastal East Asia, and the Tropical Pacific, we propose that the SSTs of the WPWP and/or El Niño-Southern Oscillation activity may have exerted a strong influence on the EASM rainfall changes during the late Holocene. Moreover, increased EASM rainfall in southern China during the last 2 ka was likely ...
Keywords	East Asian summer monsoon ; Taiwan ; Holocene ; maximum rainfall ; solar insolation ; WPSH ; Science ; Q
Language	English
Publishing date	2020-07-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Isotope constraints on nitrogen dynamics in the upper water column of the South China Sea

Xiuli Yan / Jin-Yu Terence Yang / Min Nina Xu / Ehui Tan / Zhenzhen Zheng / Wenbin Zou / Minhan Dai / Shuh-Ji Kao

Frontiers in Marine Science, Vol

2022 Volume 9

Abstract: The supply of nitrogen (N) from various external and internal sources into the euphotic zone, e.g., atmospheric N deposition (AND), upwelling, lateral intrusion, and remineralization, modulates the biogeochemical and climatic roles of oligotrophic oceans ...

Abstract	The supply of nitrogen (N) from various external and internal sources into the euphotic zone, e.g., atmospheric N deposition (AND), upwelling, lateral intrusion, and remineralization, modulates the biogeochemical and climatic roles of oligotrophic oceans and complicates N dynamics in the upper water column (≤200 m). However, our ability to resolve the mechanisms controlling upper-ocean N cycling is limited by the lack of high-resolution vertical observations. Here, we analyzed concentrations and dual isotopes of nitrate (NO3–) in the upper 200 m of the oligotrophic South China Sea. By examining dual isotopic signatures of NO3– (δ15NNO3 and δ18ONO3) and multiple associated parameters vertically throughout the upper water column, we resolved the dominant N sources and processes, including AND/N2-fixation, assimilative fractionation, and nitrification, and quantitatively evaluated their contributions in the vertical distribution of NO3–, which can be separated into the Δδ18ONO3-positive (δ18ONO3−obs−δ18ONO3−200m>0) and Δδ18ONO3-negative layers (δ18ONO3−obs−δ18ONO3−200m<0) according to the deviation in δ18ONO3 at a given depth (δ18ONO3-obs) from that at 200 m (δ18ONO3-200m). In the Δδ18ONO3-positive layer, the NO3– assimilated by phytoplankton was largely sourced from nitrification (39 ± 11%) and AND/N2 fixation (17-28%), whereas these two processes accounted for 17 ± 10% and 7 ± 6% of the total NO3– pool in the Δδ18ONO3-negative layer. Considering a substantial contribution of the regenerated (nitrification-sourced) NO3– to the total NO3– pool especially in the Δδ18ONO3-positive layer, caution should be taken that the new production assessed by the rates of NO3– uptake may be significantly overestimated in the SCS. These findings not only highlight the importance of these biogeochemical processes to NO3– dynamics in the upper water column of marginal seas, but also with important implications for the estimation of biological carbon pump and/or the f-ratio.
Keywords	nitrogen dynamcis ; South China Sea (SCS) ; nitrification ; external nitrogen source ; nitrogen isotope (δ15N) ; nitrogen uptake ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
Subject code	551
Language	English
Publishing date	2022-12-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: The biological transformation of ammonium and urea in a eutrophic estuarine system in Southern China

Jin-Ming Tang / Min Nina Xu / Yuxuan Lin / Huangxin Chen / Haoquan Jin / Li-Li Han / Wenbin Zou / Shuh-Ji Kao

Frontiers in Marine Science, Vol

2022 Volume 9

Abstract: Estuaries channel large amounts of anthropogenic nitrogen (N) from continents to the offshore where productivity is widely limited by N and phosphorus. Ammonium and urea, two reduced forms of anthropogenic N commonly observed, are the preferred ... ...

Abstract	Estuaries channel large amounts of anthropogenic nitrogen (N) from continents to the offshore where productivity is widely limited by N and phosphorus. Ammonium and urea, two reduced forms of anthropogenic N commonly observed, are the preferred substrates for various microorganisms (e.g., uptake by phytoplankton or bacteria and oxidation by nitrifier). Yet, it remains underexplored how they transform and their concentrations vary during transport in the estuary which may influence the offshore microbial community. We applied 15N isotope tracer incubation techniques to determine the two main bio-consumption processes, i.e., uptake and oxidation, of ammonium and urea, in the dark for the Jiulong River Estuary, a eutrophic estuary in southeastern China. Results showed that light penetration depth ranged from 0.8-3.3 m leaving 76% of estuary water bodies to stay in dark situations throughout a day. Ammonia oxidation, which favors dark conditions, dominates the estuarine regenerated-N cycle, showing the rank: ammonia oxidation > ammonium uptake >> urea uptake ≈ urea oxidation. By compiling the reported case studies, we found the relatively low ratio of urea oxidation to ammonia oxidation was accompanied by a relatively high ammonium concentration. Microorganisms’ high preference for ammonium over urea may lead to an inhibitory-like phenomenon. An analogous effect was evident by the increased urea uptake at downstream when ammonium was down to a few µM. The obstructed urea utilization resulted in 10 times longer lifetime for urea relative to ammonium (surface: 19 ± 9 days; bottom 12 ± 7 days). Such an inhibitory-like effect allows urea to be preserved in the estuary and allows urea to be transported farther offshore to stimulate microorganisms capable of utilizing urea, which may have significant impacts on offshore ecology.
Keywords	urea oxidation ; urea uptake ; ammonia oxidation ; ammonium uptake ; Jiulong River Estuary ; estuarine nitrogen cycle ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
Subject code	500
Language	English
Publishing date	2022-12-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Seasonal variations, source apportionment and dry deposition of chemical species of total suspended particulate in Pengjia Yu Island, East China Sea

Yu-Xiao, Li / Shu-Han, Liu / Li, Luo / Shu-Di, Yang / Bin-Yu, Lu / Chen, Wang / Shih-Chieh, Hsu / Shuh-Ji, Kao

Marine Pollution Bulletin. 2023 Feb., v. 187 p.114608-

2023

Abstract: Total of 172 total suspended particulate (TSP) samples and its chemical compositions were collected and analyzed from January to December 2010 in Pengjia Yu Island, an open region in East China Sea (ECS). Despite the predominance of sea-salt major ions ( ... ...

Abstract	Total of 172 total suspended particulate (TSP) samples and its chemical compositions were collected and analyzed from January to December 2010 in Pengjia Yu Island, an open region in East China Sea (ECS). Despite the predominance of sea-salt major ions (Na⁺, Cl⁻), the presence of non-sea-salt SO₄²⁻ (nss-SO₄²⁻) and NO₃⁻ as well as combustion-derived trace metals clearly establishes the impact of anthropogenic sources over ECS. The annual contributions of coal, heavy-fuel oil and traffic to the measured chemical species were 21.0 %, 15.0 % and 15.5 %, respectively. Especially in spring, the contributions of crustal minerals to measured chemical species during dust period (33.6 %) were higher than that (13.2 %) during non-dust period. The calculated annual average dry deposition fluxes for trace metals and total inorganic nitrogen were 246.1 ± 345.8 μg/m²/d and 2950.4 ± 2245.0 μg/m²/d, suggesting that atmospheric deposition is an important source of nutrient elements for the south of ECS.
Keywords	chemical species ; coal ; dry deposition ; dust ; marine pollution ; nitrogen ; oils ; spring ; traffic ; East China Sea ; Aerosols ; Water-soluble inorganic ions ; Trace metals ; Seasonal variations ; Source apportionment
Language	English
Dates of publication	2023-02
Publishing place	Elsevier Ltd
Document type	Article ; Online
ZDB-ID	2001296-2
ISSN	1879-3363 ; 0025-326X
ISSN (online)	1879-3363
ISSN	0025-326X
DOI	10.1016/j.marpolbul.2023.114608
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Particle-associated denitrification is the primary source of N2O in oxic coastal waters

Xianhui S. Wan / Hua-Xia Sheng / Li Liu / Hui Shen / Weiyi Tang / Wenbin Zou / Min N. Xu / Zhenzhen Zheng / Ehui Tan / Mingming Chen / Yao Zhang / Bess B. Ward / Shuh-Ji Kao

Nature Communications, Vol 14, Iss 1, Pp 1-

2023 Volume 13

Abstract: Abstract The heavily human-perturbed coastal oceans are hotspots of nitrous oxide (N2O) emission to the atmosphere. The processes underpinning the N2O flux, however, remain poorly understood, leading to large uncertainties in assessing global N2O budgets. ...

Abstract	Abstract The heavily human-perturbed coastal oceans are hotspots of nitrous oxide (N2O) emission to the atmosphere. The processes underpinning the N2O flux, however, remain poorly understood, leading to large uncertainties in assessing global N2O budgets. Using a suite of nitrogen isotope labeling experiments, we show that multiple processes contribute to N2O production throughout the estuarine-coastal gradient, sustaining intensive N2O flux to the atmosphere. Unexpectedly, denitrification, rather than ammonia oxidation as previously assumed, constitutes the major source of N2O in well-oxygenated coastal waters. Size-fractionated manipulation experiments with gene analysis further reveal niche partitioning of ammonia oxidizers and denitrifiers across the particle size spectrum; denitrification dominated on large particles and ammonia oxidizers on small particles. Total N2O production rate increases with substrate and particle concentrations, suggesting a crucial interplay between nutrients and particles in controlling N2O production. The controlling factors identified here may help understand climate feedback mechanisms between human activity and coastal oceans.
Keywords	Science ; Q
Subject code	551
Language	English
Publishing date	2023-12-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Distribution and Activity of Ammonia-Oxidizers on the Size-Fractionated Particles in the Pearl River Estuary

Li Ma / Shangjin Tan / Hongbin Liu / Shuh-Ji Kao / Minhan Dai / Jin-Yu Terence Yang

Frontiers in Marine Science, Vol

2021 Volume 8

Abstract: To distinguish between the distribution and activity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in the Pearl River estuary (PRE), we investigated the DNA- and cDNA-based β-proteobacterial and archaeal amoA genes on three size- ...

Abstract	To distinguish between the distribution and activity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in the Pearl River estuary (PRE), we investigated the DNA- and cDNA-based β-proteobacterial and archaeal amoA genes on three size-fractionated particles of >3.0 μm, 0.45–3.0 μm, and 0.22–0.45 μm. Results showed that AOB were more abundant in the freshwater with high concentrations of ammonium (NH4+) and low dissolved oxygen, whereas AOA were dominant in the NH4+-depleted seawater and sensitive to temperature. Obvious shifts in ammonia-oxidizing communities were found along the salinity gradient in the PRE. AOB clearly presented a particle-associated nature, as evidenced by higher relative abundance of amoA genes attached to the large particles (>3.0 μm) and their transcripts exclusively detected on this fraction. Moreover, higher transcriptional activity (indicated by the cDNA/DNA ratio) of AOB on the large particles, suggesting AOB were actively involved in ammonia oxidation despite their lower abundance in the mid- and lower estuarine regions. In contrast, AOA exhibited higher transcriptional activity on the 0.45–3.0 μm and 0.22–0.45 μm particles, implying the free-living strategy of these microbes. Together, these findings from field observations provide useful information on the ecological strategies of ammonia-oxidizing communities in response to different environmental conditions.
Keywords	ammonia-oxidizing bacteria ; ammonia-oxidizing archaea ; size-fractionated particles ; Pearl River estuary ; environmental factors ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
Language	English
Publishing date	2021-08-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Seasonal variations, source apportionment and dry deposition of chemical species of total suspended particulate in Pengjia Yu Island, East China Sea.

Yu-Xiao, Li / Shu-Han, Liu / Li, Luo / Shu-Di, Yang / Bin-Yu, Lu / Chen, Wang / Shih-Chieh, Hsu / Shuh-Ji, Kao

Marine pollution bulletin

2023 Volume 187, Page(s) 114608

Abstract	Total of 172 total suspended particulate (TSP) samples and its chemical compositions were collected and analyzed from January to December 2010 in Pengjia Yu Island, an open region in East China Sea (ECS). Despite the predominance of sea-salt major ions (Na
MeSH term(s)	Particulate Matter/analysis ; Air Pollutants/analysis ; Seasons ; Dust/analysis ; China ; Ions/analysis ; Minerals ; Coal/analysis ; Environmental Monitoring ; Aerosols/analysis
Chemical Substances	Particulate Matter ; Air Pollutants ; Dust ; Ions ; Minerals ; Coal ; Aerosols
Language	English
Publishing date	2023-01-16
Publishing country	England
Document type	Journal Article
ZDB-ID	2001296-2
ISSN	1879-3363 ; 0025-326X
ISSN (online)	1879-3363
ISSN	0025-326X
DOI	10.1016/j.marpolbul.2023.114608
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Development and validation of a HPLC/FLD method combined with online derivatization for the simple and simultaneous determination of trace amino acids and alkyl amines in continental and marine aerosols.

Xiongfeng Huang / Shuh-Ji Kao / Jing Lin / Xiaofei Qin / Congrui Deng

PLoS ONE, Vol 13, Iss 11, p e

2018 Volume 0206488

Abstract: A method was developed for simultaneous determination of 15 amino acids and 7 alkyl amines. The method was based on the employment of high performance liquid chromatography/fluorescence detection and online derivatization with o-phthaldiadehyde. The 22 ... ...

Abstract	A method was developed for simultaneous determination of 15 amino acids and 7 alkyl amines. The method was based on the employment of high performance liquid chromatography/fluorescence detection and online derivatization with o-phthaldiadehyde. The 22 derivatives were separated within 30 min including the equilibration time and detected by a fluorescence detector at an excitation wavelength of 230 nm and emission wavelength of 450 nm. The analysis procedure was satisfactorily validated by the reproducibility, recovery, linearity and detection limit of the analytes. The relative standard deviations (RSDs) of retention time and peak area for individual amino acids and alkyl amines were consistently less than 0.30% and 2.35%, respectively. Good recovery values ranging from 70% to 109% were obtained. The proposed method showed good linearity (R2≥0.99) in the range of 0.125-125 μM/L for amino acids and 2.5-5000 ng/L for alkyl amines. The detection limit ranged from 0.13 pM to 0.37 pM for individual amino acids and from 0.9 ng to 7.2 ng for individual alkyl amines. The developed and validated method was successfully applied to the quantitative analysis of amino acids and alkyl amines in continental and marine aerosols in China. Among the identified organic nitrogen compounds, 7 amino acids and 6 alkyl amines were detected in every aerosol sample. Glycine was the dominant amino acid, with the average of 130.93 pmol/m3 (accounting for 83% of the total amino acids) and 137.22 pmol/m3 (accounting for 66% of the total amino acids) in continental and marine aerosols in China, respectively. Methylamine and ethanolamine were the most abundant alkyl amines, contributing 87% and 64% to the total alkyl amines in continental and marine aerosols in China, respectively. This work provided an accurate, sensitive and simple method to determine simultaneously amino acids and alkyl amines, and applied the proposed method to the first investigation of amino acids in Shanghai and amino acids and alkyl amines in Huaniao Island in China. ...
Keywords	Medicine ; R ; Science ; Q
Subject code	540
Language	English
Publishing date	2018-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Aerosols as a source of dissolved black carbon to the ocean

Hongyan Bao / Jutta Niggemann / Li Luo / Thorsten Dittmar / Shuh-Ji Kao

Nature Communications, Vol 8, Iss 1, Pp 1-

2017 Volume 7

Abstract: The contribution of atmospheric deposition to the oceanic dissolved black carbon pool (DBC) is unclear. Here, the authors show that water-soluble black carbon is positively correlated with water-soluble organic carbon in marine aerosols, and that ... ...

Abstract	The contribution of atmospheric deposition to the oceanic dissolved black carbon pool (DBC) is unclear. Here, the authors show that water-soluble black carbon is positively correlated with water-soluble organic carbon in marine aerosols, and that atmospheric deposition is a significant source of oceanic DBC.
Keywords	Science ; Q
Language	English
Publishing date	2017-09-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Aerosols as a source of dissolved black carbon to the ocean

Hongyan Bao / Jutta Niggemann / Li Luo / Thorsten Dittmar / Shuh-Ji Kao

Nature Communications, Vol 8, Iss 1, Pp 1-

2017 Volume 7

Abstract	The contribution of atmospheric deposition to the oceanic dissolved black carbon pool (DBC) is unclear. Here, the authors show that water-soluble black carbon is positively correlated with water-soluble organic carbon in marine aerosols, and that atmospheric deposition is a significant source of oceanic DBC.
Keywords	Science ; Q
Language	English
Publishing date	2017-09-01T00:00:00Z
Publisher	Nature Publishing Group
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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