@article {2700,
	title = {Carbon Cycling in the World{\textquoteright}s Deepest Blue Hole},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {125},
	year = {2020},
	month = {Jan-02-2020},
	abstract = {Blue holes are unique geomorphological features with steep biogeochemical gradients and distinctive microbial communities. Carbon cycling in blue holes, however, remains poorly understood. Here we describe potential mechanisms of dissolved carbon cycling in the world{\textquoteright}s deepest blue hole, the Yongle Blue Hole (YBH), which was recently discovered in the South China Sea. In the YBH, we found some of the lowest concentrations (e.g., 22 μM) and oldest ages (e.g., 6,810 years before present) of dissolved organic carbon, as well as the highest concentrations (e.g., 3,090 μM) and the oldest ages (e.g., 8,270 years before present) of dissolved inorganic carbon observed in oceanic waters. Sharp gradients of dissolved oxygen, H2S, and CH4 and changes in bacterially mediated sulfur cycling with depth indicated that sulfur- and/or methane-based metabolisms are closely linked to carbon cycling in the YBH. Our results showed that the YBH is a unique and easily accessible natural laboratory for examining carbon cycling in anoxic systems, which has potential for understanding carbon dynamics in both paleo and modern oceans{\textemdash}particularly in the context of global change.},
	keywords = {anoxia, carbon cycling, dissolved carbon, radiocarbon, sulfur cycling, Yongle blue hole},
	issn = {2169-8953},
	doi = {10.1029/2019JG005307},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JG005307},
	author = {Yao, P. and Wang, X. C. and Bianchi, T. S. and Yang, Z. S. and Fu, L. and Zhang, X. H. and Chen, L. and Zhao, B. and Morrison, E. S. and Shields, M. R. and Liu, Y. N. and Bi, N. S. and Qi, Y. Z. and Zhou, S. and Liu, J. W. and Zhang, H. H. and Zhu, C. J. and Yu, Z. G.}
}
@article {607,
	title = {Preservation of black carbon in the shelf sediments of the East China Sea},
	journal = {Chinese Science Bulletin},
	volume = {52},
	year = {2007},
	note = {232knTimes Cited:13Cited References Count:28},
	month = {Nov},
	pages = {3155-3161},
	abstract = {Concentrations and carbon isotopic (C-14, C-13) compositions of black carbon (BC) were measured for three sediment cores collected from the Changjiang River estuary and the shelf of the East China Sea. BC concentrations ranged from 0.02 to 0.14 mg/g (dry weight), and accounted for 5\% to 26\% of the sedimentary total organic carbon (TOC) pool. Among the three sediment cores collected at each site, sediment from the Changjiang River estuary had relatively high BC contents compared with the sediments from the East China Sea shelf, suggesting that the Changjiang River discharge played an important role in the delivery of BC to the coastal region. Radiocarbon measurements indicate that the ages of BC are in the range of 6910 to 12250 years old B. P. (before present), that is in general, 3700 to 9000 years older than the C-14 ages of TOC in the sediments. These variable radiocarbon ages suggest that the BC preserved in the sediments was derived from the products of both biomass fire and fossil fuel combustion, as well as from ancient rock weathering. Based on an isotopic mass balance model, we calculated that fossil fuel combustion contributed most (60\%. 80\%) of the BC preserved in these sediments and varied with depth and locations. The deposition and burial of this "slow-cycling" BC in the sediments of the East China Sea shelf represent a significant pool of carbon sink and could greatly influence carbon cycling in the region.},
	issn = {1001-6538},
	doi = {10.1007/s11434-007-0452-1},
	author = {Wang, X. C. and Li, A. C.}
}
@article {599,
	title = {Variability in radiocarbon ages of biochemical compound classes of high molecular weight dissolved organic matter in estuaries},
	journal = {Estuarine Coastal and Shelf Science},
	volume = {68},
	year = {2006},
	note = {057ogTimes Cited:6Cited References Count:41},
	month = {Jun},
	pages = {188-194},
	abstract = {High molecular weight dissolved organic matter (HMW-DOM, > 1000 Da) represents a major fraction (> 30\%) of dissolved organic carbon (DOC) in the ocean and thus plays an important role in the global biogeochemical cycling of carbon and many other elements. Its organic sources and formation mechanisms, however, are still not well understood especially in estuarine and coastal regions where multiple natural and anthropogenic sources contribute to total HMW-DOM. In this paper we report our measurements of natural radiocarbon (C-14) abundances and stable carbon isotope (C-13) compositions of the major biochemical compound classes: amino acids, carbohydrates and lipids separated from eight HMW-DOM samples collected from five US estuaries as part of our on-going study of sources, distribution and transport of chromophoric dissolved organic matter (CDOM) in estuarine and coastal waters. Distinct differences in both C-14 and C-13 values were found among the bulk HMW-DOM samples as well as the individual compound classes. Radiocarbon ages of the major compound classes varied by as much as 27,000 years in a single sample. The calculated average radiocarbon ages of the compound fractions of HMW-DOM indicate that the total lipid fraction is very "old", while the acid-insoluble fraction is slightly younger. Total amino acid and carbohydrate fractions, however, have relatively modern apparent C-14 ages. The significant variability in C-14 ages among the compound classes indicates not only multiple organic carbon sources but also different formation and turnover pathways controlling the cycling of different biochemical components of HMW-DOM in estuarine and coastal waters. (c) 2006 Elsevier Ltd. All rights reserved.},
	issn = {0272-7714},
	doi = {10.1016/j.eccs.2006.01.018},
	author = {Wang, X. C. and Callahan, J. and Chen, R. F.}
}
@article {1962,
	title = {Biogeochemical investigations of marine methane seeps, Hydrate Ridge, Oregon},
	journal = {Journal of Geophysical Research-Biogeosciences},
	volume = {110},
	year = {2005},
	note = {090wnTimes Cited:19
Cited References Count:72
},
	month = {Nov 10},
	pages = {1-17},
	abstract = {[1] A series of biogeochemical studies were conducted at the southern summit of Hydrate Ridge, offshore Oregon. Using the submersible DSV Alvin, sediment push cores were collected from two distinct seep environments characterized by the presence of clam fields (CF) or microbial mats (MM) at the sediment-water interface; samples were also collected from a nearby reference site characterized by a barren surface at the sediment-water interface. Sediment samples from each setting were analyzed for the depth distributions of total organic carbon (concentrations, delta C-13 and Delta C-14), total sedimentary nitrogen, and microbial abundance. Pore fluids were extracted and analyzed for sulfate, alkalinity, sulfide, organic carbon, and volatile organic acids. These depth distributions clearly indicate the presence of three distinctive biogeochemical settings in the surface sediments of Hydrate Ridge, and provide the basis for a comparative biogeochemical analysis. Both CF and MM sites display properties indicating enhanced microbial activity in the subsurface, compared with the reference site. MM sites display evidence of net biomass production in the subsurface; however, a loss of sediment nitrogen relative to the reference site indicates that mineralization is also enhanced. Calculations based on the removal of nitrogen indicate that greater than 30\% of autochthonous organic material is lost to enhanced mineralization in the top 23 cm of one MM site. An isotope mass balance of sediment-bound organic carbon indicates a mixed source, including methane and allochthonous organic carbon dissolved in the seep fluids. The concentrations of organic carbon dissolved in seep fluids reach values of 22 mM and provide a first indication that advective transport of dissolved organic carbon from great depth may supply an important source of energy and carbon to "methane seep{\textquoteright}{\textquoteright} communities.},
	keywords = {anaerobic oxidation, authigenic carbonates, cascadia convergent margin, community structure, dissolved organic-carbon, fluid-flow, ne pacific, odp site 892b, phylogenetic analysis, sulfate-reducing bacteria},
	isbn = {0148-0227},
	doi = {10.1029/2005JG000025},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000240984200001},
	author = {Valentine, D. L. and Kastner, M. and Wardlaw, G. D. and Wang, X. C. and Purdy, A. and Bartlett, D. H.}
}
@article {2009,
	title = {Stable carbon and nitrogen isotopic compositions of organic compound classes in high molecular weight dissolved organic matter from four U. S. estuaries},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {68},
	year = {2004},
	note = {id: 515},
	month = {2004},
	pages = {2681-2691},
	author = {Wang, X. C. and Altabet, A. M. and Callahan, J. and Chen, R. F.}
}
@article {767,
	title = {Contribution of "old" carbon from natural marine hydrocarbon seeps to sedimentary and dissolved organic carbon pools in the Gulf of Mexico},
	journal = {Geophysical Research Letters},
	volume = {28},
	year = {2001},
	note = {467jmTimes Cited:20Cited References Count:25},
	month = {Sep 1},
	pages = {3313-3316},
	abstract = {Natural radiocarbon (C-14) abundances and stable carbon isotope (delta C-13) compositions were measured for sediment total organic carbon (TOC), and total lipid fractions of sediments, bottom water, and hydrate-water collected from two hydrocarbon seepage sites in Green Canyon, Northern Gulf of Mexico to determine the contribution of "old" carbon from seeps to sediment TOC and dissolved organic carbon (DOC) pools. Our results indicate that 40-60\% of the organic carbon preserved in the sediments and 30\% of the DOC in the deep water above the seeps were seep-derived C-14-depleted organic carbon. This new evidence along with our previous studies suggest that natural marine hydrocarbon seepage could be a significant source contributing "old" carbon to the marine environment. Our findings suggest that the global importance and the long-term impact of this contribution to biogeochemical carbon cycling in the ocean need to be more thoroughly investigated.},
	issn = {0094-8276},
	doi = {10.1029/2001gl013430},
	author = {Wang, X. C. and Chen, R. F. and Whelan, J. and Eglinton, L.}
}
