@article {2923,
	title = {Carbon Isotopic and Lithologic Constraints on the Sources and Cycling of Inorganic Carbon in Four Large Rivers in China: Yangtze, Yellow, Pearl, and Heilongjiang},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {126},
	year = {2021},
	month = {Jan-02-2021},
	abstract = {Transport of terrigenous carbon by rivers has been affected extensively by climate change and anthropogenic activities in China over the last few decades. Here, we present results on carbon isotopes (C-13, C-14) of dissolved and particulate inorganic carbon (DIC and PIC) and combined with major lithologic ions measured in the four largest rivers in China, namely, the Yangtze, Yellow, Pearl, and Heilongjiang rivers, to reveal the sources and transport of terrigenous inorganic carbon in the rivers. The DIC concentrations showed large variations in the four rivers and ranged from 253 to 3,122 mu M. The Yangtze, Yellow and Pearl rivers transported high DIC contents that had low Delta C-14 values of millennium-aged DIC and very old PIC; however, the Heilongjiang River presented a lower DIC concentration with much younger C-14 ages than the global average (1,100 mu M). The strong correlations between the DIC isotope values and major lithological ions (Ca2+ and Mg2+) suggest that chemical weathering played important but variable roles in controlling the production and fate of DIC in the rivers. Using dual isotopes and the MixSIAR model, we calculated that the chemical weathering of carbonate rocks contributed 95 +/- 5\% of the riverine DIC to the headwater of the Yangtze River while silicate rock weathering and riverine organic matter respiration contributed 62 +/- 25\% and 5 +/- 5\% of the DIC in the middle and lower reaches of the river, respectively. In contrast, chemical weathering of silicate rocks contributed the dominant fraction of DIC in the Yellow (55 +/- 17\%), Pearl (61 +/- 20\%) and Heilongjiang (83 +/- 29\%) rivers.},
	keywords = {Carbon cycle, Chemical weathering, inorganic carbon in large rivers, radiocarbon, stable carbon isotope},
	issn = {2169-8953},
	doi = {10.1029/2020JG005901},
	url = {https://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\&SrcApp=search\&SrcAuth=Alerting\&SID=7EQ3XpZtZiWye3DFos4\&customersID=Alerting\&mode=FullRecord\&IsProductCode=Yes\&AlertId=4d48b20a-7d27-4fa2-},
	author = {Shan, Sen and Luo, Chunle and Qi, Yuanzhi and Cai, Wei-Jun and Sun, Shuwen and Fan, Di and Wang, Xuchen}
}
@article {2914,
	title = {Carbon cycling in the deep Mariana Trench in the western north Pacific Ocean: Insights from radiocarbon proxy data},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	volume = {164},
	year = {2020},
	month = {Jan-10-2020},
	pages = {103370},
	abstract = {The Mariana Trench in the western North Pacific (NP) contains the deepest (11,000 m) point in the ocean and thus remains the least explored environment. Carbon cycling in the deep Mariana Trench is largely unknown and remains a curious mystery. Here, we report radiocarbon (Delta C-14) and stable carbon isotope (delta C-13) compositions of dissolved inorganic and organic carbon (DIC and DOC) and sinking particulate organic carbon (POC) for samples collected at 2000 m, 4000 m and 6000 m from the Mariana Trench in the western NP. DOC had much lower Delta C-14 values (-189 parts per thousand to -538 parts per thousand) than DIC (38 parts per thousand to -236 parts per thousand) and POC (11 parts per thousand-38 parts per thousand) at the same depths, indicating the different cycling processes and time scales of different carbon pools. The C-14 ages of DOC were approximately 1700 years and 4400 years older than those of DIC in the surface (2 m) and deep (10,000 m) waters of the Mariana Trench. Both DOC and DIC Delta C-14 values at hadal depths (>6000 m) in the trench are comparable to values at other sites in the deep NP, suggesting that water movement and mixing at hadal depths in the Mariana Trench are active and follow the deep-water circulation patterns of the NP. POC fluxes at the three deep depths showed large variations, but their modern Delta C-14 values indicate that the effective biological pump that drives fresh surface-produced particles to sink rapidly to deep depths in the trench could provide essential food sources for microbial and benthic communities living in an extremely harsh environment of the Mariana Trench.},
	keywords = {carbon cycling, Mariana trench, North pacific ocean, Particle flux, radiocarbon, stable carbon isotope},
	issn = {09670637},
	doi = {10.1016/j.dsr.2020.103370},
	url = {https://apps.webofknowledge.com/InboundService.do?product=WOS\&Func=Frame\&DestFail=http\%3A\%2F\%2Fwww.webofknowledge.com\&SrcApp=search\&SrcAuth=Alerting\&SID=5FcsGoXKXNO2xQfU7KW\&customersID=Alerting\&mode=FullRecord\&IsProductCode=Yes\&AlertId=4d48b20a-7d27-4fa2-},
	author = {Shan, Sen and Qi, Yuanzhi and Tian, Jiwei and Wang, Xuchen and Luo, Chunle and Zhou, Chun and Zhang, Xiao-Hua and Xin, Yu and Wang, Yonghong}
}
@article {2915,
	title = {Dissolved black carbon is not likely a significant refractory organic carbon pool in rivers and oceansAbstract},
	journal = {Nature Communications},
	volume = {11},
	year = {2020},
	month = {Jan-12-2020},
	abstract = {Rivers are the major carriers of dissolved black carbon (DBC) from land to ocean; the sources of DBC during its continuous transformation and cycling in the ocean, however, are not well characterized. Here, we present new carbon isotope data for DBC in four large and two small mountainous rivers, the Yangtze and Yellow river estuaries, the East China Sea and the North Pacific Ocean. We found that the carbon isotope signatures of DBC are relatively homogeneous, and the DBC C-14 ages in rivers are predominantly young and increase during continuous transport and cycling in the ocean. The results of charcoal leaching experiments indicate that DBC is released from charcoal and degraded by bacteria. Our study suggests that riverine DBC is labile and respired during transport and mixing into the ocean and that residual DBC is cycled and aged on the same time scales as bulk DOC in the ocean. Black carbon is a recalcitrant byproduct of biomass burning that ultimately accumulates in oceanic sinks. Here the authors assessed the sources and cycling of dissolved black carbon in rivers and oceans, finding that oceanic pools are cycled and aged on the same time scales as dissolved organic carbon.},
	keywords = {Changjiang, cycle, flux, HUANGHE RIVERS, level, particulate, quantification, radiocarbon, sea},
	doi = {10.1038/s41467-020-18808-8},
	url = {http://www.nature.com/articles/s41467-020-18808-8http://www.nature.com/articles/s41467-020-18808-8.pdfhttp://www.nature.com/articles/s41467-020-18808-8.pdfhttp://www.nature.com/articles/s41467-020-18808-8},
	author = {Qi, Yuanzhi and Fu, Wenjing and Tian, Jiwei and Luo, Chunle and Shan, Sen and Sun, Shuwen and Ren, Peng and Zhang, Hongmei and Liu, Jiwen and Zhang, Xiaohua and Wang, Xuchen}
}
@article {2667,
	title = {Sources and radiocarbon ages of organic carbon in different grain size fractions of Yellow River-transported particles and coastal sediments},
	journal = {Chemical Geology},
	volume = {534},
	year = {2020},
	month = {Jan-02-2020},
	pages = {119452},
	keywords = {organic matter, RadiocarbonStable carbon isotope, Sediment grain size, Yellow River},
	issn = {00092541},
	doi = {10.1016/j.chemgeo.2019.119452},
	url = {https://www.sciencedirect.com/science/article/pii/S0009254119305819},
	author = {Ge, Tiantian and Xue, Yuejun and Jiang, Xueyan and Zou, Li and Wang, Xuchen}
}
@article { ISI:000482379400088,
	title = {Sources and sink of black carbon in Arctic Ocean sediments},
	journal = {SCIENCE OF THE TOTAL ENVIRONMENT},
	volume = {689},
	year = {2019},
	month = {NOV 1},
	pages = {912-920},
	abstract = {The concentrations and carbon isotopic (C-13, C-14) compositions of total organic carbon (TOC) and black carbon (BC) were measured for four sediment cores collected from the shelf to slope in the Arctic Ocean. Contents of TOC and BC ranged from 0.46\% to 1.94\% and 0.04\% to 0.13\% by dry weight, and BC accounted for 3.5\% to 15.2\% of the TOC preserved in the shelf and slope sediments. Sediment of the Chukchi shelf contained relatively high BC contents compared with the sediments of the Arctic slope, suggesting strong influence from the river and terrestrial inputs to the shelf region. Radiocarbon measurements revealed that the ages of BC are in the range of 7330 to 29,700 years (before present) and they are 4093 to 7723 years older than the C-14 ages of TOC preserved in the same sediment depths. Based on an isotopic mass balance model, we calculated that fossil fuel combustion contributed 62-96\%, and biomass burning contributed 4-38\% of the BC pool in the sediments of the study area. This {\textquoteleft}{\textquoteleft}slow-cycling{\textquoteright}{\textquoteright} old BC is an important fraction of the inert organic carbon pool preserved in the sediments, and represents a significant sink of atmospheric CO2 and global carbon cycle. With the thawing permafrost caused by continuous global warming, the size of this BC pool mobilized and exported by rivers to the Arctic Ocean could increase in the future. (C) 2019 Elsevier B.V. All rights reserved.},
	issn = {0048-9697},
	doi = {10.1016/j.scitotenv.2019.06.437},
	author = {Ren, Peng and Liu, Yanguang and Shi, Xuefa and Sun, Shuwen and Fan, Di and Wang, Xuchen}
}
@article {2616,
	title = {Large Variability of Dissolved Inorganic Radiocarbon in the Kuroshio Extension of the Northwest North PacificABSTRACT},
	journal = {Radiocarbon},
	volume = {60264317255},
	year = {2018},
	month = {Jan-04-2018},
	pages = {691 - 704},
	abstract = {Radiocarbon (C-14) in dissolved inorganic carbon (DIC) was measured for water samples collected from six deep stations in the Kuroshio Extension (KE) region in the northwestern North Pacific in April-May 2015. Vertical profiles of Delta C-14-DIC indicate that bomb-produced Delta
C-14 was present from the surface to similar to 1500 m water depth. Large variations in Delta C-14-DIC values (300 parts per thousand) were
observed at 500 m water depth among the stations and the differences were likely controlled by transport and mixing dynamics of different
water masses in the region. The major Pacific western boundary currents, such as Kuroshio and Oyashio and regional mesoscale eddies, could play important roles affecting the observed Delta C-14-DIC variability. The depth profiles of both Delta C-14-DIC and DIC concentrations can be predicted by the solution mixing model and can be used as conservative tracers of water mass movement and water parcel homogenization in the
ocean.},
	keywords = {bomb radiocarbon, carbon, intermediate water, MIXED WATER REGION, ocean, WESTERN BOUNDARY CURRENTS},
	issn = {0033-8222},
	doi = {10.1017/RDC.2017.143},
	url = {https://www.cambridge.org/core/product/identifier/S0033822217001436/type/journal_articlehttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822217001436},
	author = {Ding, Ling and Ge, Tiantian and Gao, Huiwang and Luo, Chunle and Xue, Yuejun and Druffel, Ellen R M and Wang, Xuchen}
}
@article {2766,
	title = {Sources and radiocarbon ages of aerosol organic carbon along the east coast of China and implications for atmospheric fossil carbon contributions to China marginal seas},
	journal = {Science of The Total Environment},
	volume = {619-620},
	year = {2018},
	month = {Jan-04-2018},
	pages = {957 - 965},
	abstract = {Aerosol deposition is an important mechanism for the delivery of terrestrial organic carbon (OC) to marginal seas, but OC age characteristics of aerosols are not well constrained and their contributions to sediment OC burial have not been quantified. Total suspended particle samples were collected along the east coast of China at Changdao (CD), Qingdao (QD) and Huaniao Island (HNI), and were analyzed for total organic carbon (TOC) isotopes (13C and 14C) in order to bridge this information gap. TOC δ13C and Δ14C values ranged from - 23.6 to - 30.5{\textperthousand}, and - 153 to - 687{\textperthousand}, respectively, with the latter corresponding to 14C ages ranging from 1280 to 9260 yr. Estimated contributions of fossil carbon to TOC based on 14C mass balance approach ranged from 26 to 73\%, with strong seasonal variations in fossil carbon observed at CD. Fossil carbon at CD showed the highest proportion (73\%) in winter, reflecting anthropogenic emissions and the lowest proportion (26\%) in summer, caused by biomass contribution (annual ave., 52\% {\textpm} 17\%). In contrast, the fossil carbon at both QD (57{\textendash}64\%) and HNI (57{\textendash}67\%) dominated throughout the year, reflecting local anthropogenic influences and long-range transport. Mass balance estimates indicate that atmospheric deposition and riverine export accounted for 31\% and 69\% of fossil carbon inputs to the China marginal seas (CMS) respectively, with fossil carbon burial efficiencies approaching 100\% in the CMS. On a global scale, an atmospheric fossil carbon deposition flux of 17.2 Tg C yr- 1 was estimated, equivalent to 40\% of the estimated fluvial flux to the ocean, and potentially accounting for 24{\textendash}41\% of fossil OC burial in marine sediments. Therefore, the atmospheric deposition constitutes an important source of fossil carbon to marine sediments, and could play a key role in regional and global scale OC budgets and biogeochemical cycles.},
	keywords = {AEROSOLS, China marginal seas, Fossil carbon, Radiocarbon (14C) tracer, Total organic carbon},
	issn = {00489697},
	doi = {10.1016/j.scitotenv.2017.11.201},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S004896971733259X},
	author = {Yu, Meng and Guo, Zhigang and Wang, Xuchen and Eglinton, Timothy Ian and Yuan, Zineng and Xing, Lei and Zhang, Hailong and Zhao, Meixun}
}
@article {2528,
	title = {A high resolution record of rare earth element compositional changes from the mud deposit on the inner shelf of the East China Sea: Implications for paleoenvironmental changes},
	journal = {Quaternary International},
	year = {2017},
	month = {Jan-01-2017},
	abstract = {A paleoenvironmental reconstruction of the East China Sea (ECS) is presented using rare earth element (REE) analysis of sediments from Core MZ02, which was retrieved from the inner continental shelf{\textquoteright}s mud area. The analytic results show that the total REEs in the fine sediment vary between 137.76 μg/g and 231.53 μg/g with an average value of 187.69 μg/g. Obvious changes were found during the process of sedimentation. By comparing with the REE compositions from the potential provenances, the ratios of (La/Sm)ucc and (Gd/Yb)ucc revealed that the sediments were mainly derived from river detrital outputs of the Changjiang (Yangtze River), Minjiang and mountainous rivers from western Taiwan Island. The contributions of terrestrial materials from these three main provenances were controlled by sea level change and the Taiwan Warm Current (TWC)-Chinese Coastal Current (CCC) system, which is mainly driven by the East Asian monsoon. The high sedimentation rate during the transgression period between the late Pleistocene and early Holocene (13000{\textendash}9800 a B.P.) was caused by a well-proportioned mixed provenance from Changjiang, western Taiwanese rivers and Minjiang sediments, due to the lower sea level and the location of the foreshore-nearshore face. Because of the stronger sediment reworking and erosion at the shelf edge during the early Holocene (9800{\textendash}7300 a B.P.), the strengthening summer East Asian monsoon transported the Minjiang and western Taiwanese river material northeastward, and it became the main sediment source for fine sediments in the shallow sea region of the ECS, while the Changjiang provided a relatively minor amount of detrital sediment to the shelf. The increasing strength of the TWC might have played an important role in sediment dispersal and deposition on the ECS inner shelf during the period 7300{\textendash}3500 a B.P., thus mountainous river material became the dominant sediment on the shelf of the ECS. Furthermore, the results indicate that the East Asian monsoon and the weakening of the TWC were linked to an abrupt increase in Changjiang-derived terrigenous detritus material since 3500 a B.P.; the source and sink pattern during this period is consistent with the modern sedimentation environment.},
	keywords = {East China Sea, Mud deposit, Paleoenvironmental, Provenance, Rare earth element, Sediment},
	issn = {10406182},
	doi = {10.1016/j.quaint.2016.09.056},
	url = {https://doi.org/10.1016/j.quaint.2016.09.056},
	author = {Mi, Beibei and Liu, Shengfa and Shi, Xuefa and Li, Xiaoyan and Pan, Hui-Juan and Chen, Min-Te and Wang, Xuchen}
}
@article {2527,
	title = {Mobilization and export of millennial-aged organic carbon by the Yellow River},
	journal = {Limnology and Oceanography},
	year = {2017},
	month = {Jan-04-2017},
	abstract = {A combined carbon isotope (13C and 14C) study was carried out to investigate the sources and fate of organic carbon (OC) transported by the Yellow River and preserved in the sediments of the Bohai and Yellow Seas. In 2015, the Yellow River delivered 3.14 {\texttimes} 1010 g C and 4.12 {\texttimes} 1010 g C of dissolved organic carbon (DOC) and particulate organic carbon (POC) to the Bohai Sea. Carbon isotope signatures revealed that the Yellow River transports millennial-aged DOC and POC during all seasons. The values of δ13C-DOC ranged from -24.7{\textperthousand} to -28.8{\textperthousand} in the river basin, and -21.0{\textperthousand} to -27.0{\textperthousand} in the lower reach. The 14C ages of DOC were 415{\textendash}1690 yr before present (BP) in the river basin, and they were relatively constant seasonally (1320{\textendash}1690 yr BP) in the lower reach of the river. In comparison, POC δ13C values in the river were less variable (-22.8{\textperthousand} to -25.0{\textperthousand}), but much older in both the river basin (4960 {\textpm} 1690 yr BP) and in the lower reach (4040 {\textpm} 1050 yr BP). Calculations using a dual-isotopic three-end member model revealed that biomass OC derived from C3 plants was the major source of riverine DOC, contributing 65\% {\textpm} 8\% and 52\% {\textpm} 2\% in the river basin and lower reach seasonally. Pre-aged soil OC and fossil OC from weathering contributed 21{\textendash}42\% and 6{\textendash}14\% of the DOC, respectively. In contrast, pre-aged soil OC and fossil OC contributed 60{\textendash}70\% and 17{\textendash}27\% of POC, and biomass OC contributed a minor fraction (13\% {\textpm} 7\%) of riverine POC. Our results further revealed that aged riverine POC had a major influence on OC preservation in the delta and coastal sediments of the Bohai and Yellow Seas. The age of OC in surface sediments varied widely (1610{\textendash}8275 yr) due to the influence of Yellow River input. Pre-aged soil OC and fossil OC each contributed 32\% {\textpm} 8\% and 22\% {\textpm} 14\% of OC preserved in the sediments. We estimate that about 0.27 Mt yr-1 and 0.07 Mt yr-1 of pre-aged soil OC and fossil OC accumulate in the surface sediments from POC delivered by the modern Yellow River, and 0.013 Mt yr-1 and 0.002 Mt yr-1 of pre-aged soil OC and fossil OC enters the coastal DOC cycle from riverine DOC. The millennial-aged OC delivered to coastal seas by the Yellow River therefore has profound impacts not only on carbon cycling and the carbon budget in the marginal sea, but also on coastal ecosystems and biogeochemical processes.},
	doi = {10.1002/lno.10579},
	url = {http://doi.wiley.com/10.1002/lno.10579http://onlinelibrary.wiley.com/wol1/doi/10.1002/lno.10579/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002\%2Flno.10579},
	author = {Xue, Yuejun and Zou, Li and Ge, Tiantian and Wang, Xuchen}
}
@article {2889,
	title = {Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history},
	journal = {Climate of the Past},
	volume = {13},
	year = {2017},
	month = {Jan-01-2017},
	pages = {511 - 531},
	abstract = {ediment core ARC4-BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stage {\textendash} MIS {\textendash} 1{\textendash}15, ca. 0.5{\textendash}0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktic foraminiferal numbers in core ARC4{\textendash}BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7{\textendash}8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.},
	doi = {10.5194/cp-13-511-2017},
	url = {https://cp.copernicus.org/articles/13/511/2017/},
	author = {Dong, Linsen and Liu, Yanguang and Shi, Xuefa and Polyak, Leonid and Huang, Yuanhui and Fang, Xisheng and Liu, Jianxing and Zou, Jianjun and Wang, Kunshan and Sun, Fuqiang and Wang, Xuchen}
}
@article { ISI:000375679100005,
	title = {Carbon isotopic (C-14 and C-13) characterization of fossil-fuel derived dissolved organic carbon in wet precipitation in Shandong Province, China},
	journal = {JOURNAL OF ATMOSPHERIC CHEMISTRY},
	volume = {73},
	number = {{2}},
	year = {2016},
	month = {JUN},
	pages = {207-221},
	type = {Article},
	abstract = {We present results from a 1-year study of radiocarbon and stable carbon isotope measurement of dissolved organic carbon (DOC) of wet precipitation samples collected in the Shandong province of China. A total of 32 rainfall and 4 snow samples were collected from two coastal cities (Qingdao and Yantai) and one inland site (Taian) during 2014. Concentrations of DOC in the rainwater and snow samples varied widely from 28 to 616 mu M. In general, rainwater originating from marine sources had relatively low DOC concentrations compared with continentally generated precipitation. Values of delta C-13-DOC and Delta C-14-DOC in the snow and rainwater ranged from -19.0 to -29.4 \% and -23 to -494 \%, with corresponding radiocarbon ages of 125 to 5410 years before present. The dominant DOC in the wet precipitation had a relatively old C-14 age (average 2841 years) and a depleted C-13 value (average -24.4 Years), indicating the mixing of contemporary organic carbon with C-14-depleted fossil fuel-derived soluble organic carbon in the atmosphere. Using a dual isotopic two-endmember model, we calculate that 7 \% to 52 \% of DOC in the snow and rainfall originated from fossil fuels. It is estimated that the flux of DOC in continental rainfall of China is 23 x 10(12) g C yr(-1) and of this, 7.1 x 10(12) g C yr(-1) could be fossil-fuel OC. On a global scale, the DOC flux in rainfall is estimated to be 357 Tg C yr(-1), and 110 Tg C yr(-1) could be fossil fuel-derived. Our study demonstrates that wet precipitation is an important removal process for old fossil fuel carbon from the atmosphere. This removal mechanism could play an important role in the carbon cycle, especially for the anthropogenically derived fraction, and it should be taken into consideration in global carbon cycle models.},
	keywords = {Atmospheric pollution, Fossil fuelemission, organic carbon, radiocarbon, Wet precipitation},
	issn = {0167-7764},
	doi = {10.1007/s10874-015-9323-3},
	author = {Wang, Xuchen and Ge, Tiantian and Xu, Caili and Xue, Yuejun and Luo, Chunle}
}
@article { ISI:000383622900016,
	title = {Controls on the sources and cycling of dissolved inorganic carbon in the Changjiang and Huanghe River estuaries, China: C-14 and C-13 studies},
	journal = {LIMNOLOGY AND OCEANOGRAPHY},
	volume = {61},
	number = {{4}},
	year = {2016},
	month = {JUL},
	pages = {1358-1374},
	type = {Article},
	abstract = {The Changjiang (Yangtze River) and Huanghe (Yellow River) are the two largest rivers in China, and they transport large amounts of terrestrial carbon to the coastal waters of the East China Sea and the Bohai Sea. The sources and cycling of riverine carbon in these two large river estuaries, however, have not been well studied. In this article, we present the results of dual isotope (Delta C-14 and delta C-13) measurements of dissolved inorganic carbon (DIC) collected in the low reaches of the Changjiang and Huanghe and their estuaries during two cruises in 2014. Our results indicate that both the Changjiang and Huanghe carry very high concentrations of DIC ranging from 1384 mu mol kg(-1) to 1732 mu mol kg(-1) and 2711 mu mol kg(-1) to 4120 mu mol kg(-1), respectively, and DIC levels varied with flow rates during high and low discharge periods. The cycling of DIC exhibited conservative behavior in both the Changjiang and Huanghe estuaries, suggesting DIC levels were controlled mainly by physical mixing processes. Delta C-14-DIC values indicate that the Changjiang and Huanghe transport aged DIC (1060-1380 yr old). Both Delta C-14-DIC and delta C-13-DIC values also showed conservative mixing in the two estuaries. Using a dual carbon isotopic model, we calculated that atmospheric CO2 consumed mainly by silicate weathering was a major source, contributing 65.2 +/- 9.0\% and 73.4 +/- 3.0\% of DIC in the Changjiang and Huanghe, and 96.9-97.7\% (by air-sea exchange) of DIC in the coastal waters of the East China Sea (ECS) and Bohai Sea, respectively. Our results indicate that carbonate dissolution was an important (12.3-17.4\%) but not major process controlling the high DIC levels in both rivers, as suggested previously. Compared with the large Amazon River, respiration of riverine organic matter (OM) played a less important role, contributing only 15.4-17.2\% of DIC in the two Asian rivers. Flux calculations indicate that the Changjiang and Huanghe discharged 1.46 x 10(13) g and 6.28 x 10(11) g DIC into the ECS and Bohai Sea in 2014, which were 9 and 17 times higher than the DOC fluxes in the two rivers. These large fluxes of riverine DIC, especially of aged DIC, could have significant impacts on primary production and carbon cycling in the ECS and Bohai Sea.},
	issn = {0024-3590},
	doi = {10.1002/lno.10301},
	author = {Wang, Xuchen and Luo, Chunle and Ge, Tiantian and Xu, Caili and Xue, Yuejun}
}
@article { ISI:000389875700006,
	title = {DISSOLVED INORGANIC RADIOCARBON IN THE NORTHWEST PACIFIC CONTINENTAL MARGIN},
	journal = {RADIOCARBON},
	volume = {58},
	number = {{3}},
	year = {2016},
	month = {SEP},
	pages = {517-529},
	type = {Article},
	abstract = {This article presents a modified method for extraction of dissolved inorganic carbon (DIC) from seawater for radiocarbon measurement by accelerator mass spectrometry (AMS). Standard tests indicate that the extraction efficiencies of DIC are >96\%, and the respective precisions of. Delta C-14-DIC and delta C-13-DIC analyses are 6\% and 0.1\% or better. Using the method, we report. Delta C-14-DIC profiles collected from the shelf and slope in the East China Sea (ECS) of the northwest Pacific Ocean. Both the DIC concentration and. Delta C-14-DIC in the shelf and slope regions seem primarily affected by the Kuroshio Current. It is estimated that 54-65\% of the bottom water in the shelf region could be from the intrusion of Kuroshio intermediate water, which carries a high concentration and low. Delta C-14 values of DIC, and which influenced the DIC and its Delta C-14 signature on the shelf. Compared with the. Delta C-14-DIC profiles at other sites in the northwest Pacific reported previously, it appears that the. Delta C-14-DIC distributions are mainly controlled by the major oceanic currents in the region, and large variations in. Delta C-14-DIC occurred mostly in the upper 800m of the water column. The similarity of. Delta C-14-DIC at depth suggests that the deep-water circulation patterns have been relatively stable in the northwest Pacific Ocean in the last 20 yr.},
	keywords = {continental margin, dissolved inorganic carbon, East China Sea, radiocarbon, stable carbon isotope},
	issn = {0033-8222},
	doi = {10.1017/RDC.2016.23},
	author = {Ge, Tiantian and Wang, Xuchen and Zhang, Jing and Luo, Chunle and Xue, Yuejun}
}
@article { ISI:000392927300002,
	title = {Two black carbon pools transported by the Changjiang and Huanghe Rivers in China},
	journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
	volume = {30},
	number = {{12}},
	year = {2016},
	month = {DEC},
	pages = {1778-1790},
	type = {Article},
	abstract = {Major rivers play important roles in transporting large amounts of terrestrial organic matter from land to the ocean each year, and the organic matter carried by rivers contains a significant fraction of black carbon (BC). A recent study estimated that 0.027 Gt of BC is transported in the dissolved phase by rivers each year, which accounts for similar to 10\% of the global flux of dissolved organic carbon. The relative sources of this large amount of riverine dissolved black carbon (DBC) from biomass burning (young, modern C-14) and fossil fuel (old, C-14 free) combustion are not known. We present radiocarbon measurements of BC in both dissolved and particulate phases transported by the Changjiang and Huanghe Rivers, the two largest rivers in China, during 2015. We show that two, distinct BC pools (young and old) were carried by the rivers. The DBC pool was much younger than the particulate BC (PBC) pool. Mass balance calculations indicate that most (78-85\%) of the DBC in the Changjiang and Huanghe Rivers was derived from biomass burning, and only 15-22\% was from fossil fuel combustion. In contrast, PBC from biomass burning and fossil fuel combustion were approximately equal in these two rivers. Export of PBC and DBC by the rivers are decoupled, and fluxes of PBC were 4.1 and 6.7 times higher than DBC in the Changjiang and Huanghe Rivers, respectively. The C-14 age differences of the two BC pools suggest that BC derived from biomass burning and fossil fuel combustion are mobilized in different phases and on different time scales in these rivers.},
	issn = {0886-6236},
	doi = {10.1002/2016GB005509},
	author = {Wang, Xuchen and Xu, Caili and Druffel, Ellen M. and Xue, Yuejun and Qi, Yuanzhi}
}
@article { ISI:000304550900001,
	title = {Seasonal fluxes and source variation of organic carbon transported by two major Chinese Rivers: The Yellow River and Changjiang (Yangtze) River},
	journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
	volume = {26},
	year = {2012},
	month = {MAY 25},
	type = {Article},
	abstract = {A one-year study was carried out to investigate the seasonal fluxes and source variation of organic carbon transported by two major Chinese rivers, the Yellow River and Changjiang. In 2009, the Yellow River and Changjiang transported 3.20 x 10(10) g and 1.58 x 10(12) g DOC and 3.89 x 10(11) g and 1.52 x 10(12) g POC, respectively. The dominant input of the terrestrial organic matter occurred during the high discharge period from June to July for the Yellow River and from June to August for Changjiang, accounting for 36-44\% of the DOC and 72-86\% of the POC transported by the two rivers in 2009. The Yellow River transported much higher concentrations of inorganic carbon than organic carbon, while a reverse trend was found in the Changjiang, indicating the different sources of carbon discharged by the two rivers. Using radiocarbon and stable carbon isotope measurements, we identified the different sources and seasonal variations of organic carbon transported by the Yellow River and Changjiang. The Yellow River carried old POC with radiocarbon ages ranging from 4000 to 8000 years, while POC transported by Changjiang had a relatively younger C-14 age ranging from 800 to 1060 years. The C-14 ages of DOC were relatively younger (305-1570 years) and showed less variation between the two rivers. The seasonal variations found in C-14 ages of DOC and POC indicate that a large fraction of recent-fixed labile organic carbon was transported by the two rivers in the spring and summer months. The different sources and seasonal variations in both fluxes and sources of organic carbon transported by the Yellow River and Changjiang could have an important influence on the biogeochemical cycle and ecosystems in the estuaries and adjacent coastal waters of the East China Sea.},
	issn = {0886-6236},
	doi = {10.1029/2011GB004130},
	author = {Wang, Xuchen and Ma, Haiqing and Li, Ronghua and Song, Zhensu and Wu, Jinping}
}
