@article {2980,
	title = {Organic carbon burial by river meandering partially offsets bank erosion carbon fluxes in a discontinuous permafrost floodplain},
	journal = {Earth Surface Dynamics},
	volume = {10},
	year = {2022},
	month = {05/2022},
	pages = {421 - 435},
	abstract = {Arctic river systems erode permafrost in their banks and mobilize particulate organic carbon (OC). Meandering rivers can entrain particulate OC from permafrost many meters below the depth of annual thaw, potentially enabling the production of greenhouse gases. However, the amount and fate of permafrost OC that is mobilized by river erosion is uncertain. To constrain OC fluxes due to riverbank erosion and deposition, we collected riverbank and floodplain sediment samples along the Koyukuk River, which meanders through discontinuous permafrost in the Yukon River watershed, Alaska, USA, with an average migration rate of 0.52 m yr-1. We measured sediment total OC (TOC) content, radiocarbon activity, water content, bulk density, grain size, and floodplain stratigraphy. Radiocarbon activity and TOC content were higher in samples dominated by silt as compared to sand, which we used to map OC content onto floodplain stratigraphy and estimate carbon fluxes due to river meandering. Results showed that the Koyukuk River erodes and re-deposits a substantial flux of OC each year due to its depth and high migration rate, generating a combined OC flux of a similar magnitude to the floodplain net ecological productivity. However, sediment being eroded from cutbanks and deposited as point bars had similar OC stocks (mean {\textpm} 1 SD of 125.3{\textpm}13.1 kg OC m-2 in cutbanks versus 114.0{\textpm}15.7 kg OC m-2 in point bars) whether or not the banks contained permafrost. We also observed radiocarbon-depleted biospheric OC in both cutbanks and permafrost-free point bars. These results indicate that a substantial fraction of aged biospheric OC that is liberated from floodplains by bank erosion is subsequently re-deposited in point bars rather than being oxidized. The process of aging, erosion, and re-deposition of floodplain organic material may be intrinsic to river{\textendash}floodplain dynamics, regardless of permafrost content.},
	doi = {10.5194/esurf-10-421-2022},
	url = {https://esurf.copernicus.org/articles/10/421/2022/},
	author = {Douglas, Madison M. and Li, Gen K. and Fischer, Woodward W. and Rowland, Joel C. and Kemeny, Preston C. and West, A. Joshua and Schwenk, Jon and Piliouras, Anastasia P. and Chadwick, Austin J. and Lamb, Michael P.}
}
@article {2930,
	title = {Coal fly ash is a major carbon flux in the Chang Jiang (Yangtze River) basin},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {118},
	year = {2021},
	month = {Jan-05-2023},
	pages = {e1921544118},
	abstract = {Fly ash-the residuum of coal burning-contains a considerable amount of fossilized particulate organic carbon (FOCash) that remains after high-temperature combustion. Fly ash leaks into natural environments and participates in the contemporary carbon cycle, but its reactivity and flux remained poorly understood. We characterized FOCash in the Chang Jiang (Yangtze River) basin, China, and quantified the riverine FOCash fluxes. Using Raman spectral analysis, ramped pyrolysis oxidation, and chemical oxidation, we found that FOCash is highly recalcitrant and unreactive, whereas shale-derived FOC (FOCrock) was much more labile and easily oxidized. By combining mass balance calculations and other estimates of fly ash input to rivers, we estimated that the flux of FOCash carried by the Chang Jiang was 0.21 to 0.42 Mt C center dot y-1 in 2007 to 2008-an amount equivalent to 37 to 72\% of the total riverine FOC export. We attributed such high flux to the combination of increasing coal combustion that enhances FOCash production and the massive construction of dams in the basin that reduces the flux of FOCrock eroded from upstream mountainous areas. Using global ash data, a first-order estimate suggests that FOCash makes up to 16\% of the present-day global riverine FOC flux to the oceans. This reflects a substantial impact of anthropogenic activities on the fluxes and burial of fossil organic carbon that has been made less reactive than the rocks from which it was derived.},
	issn = {0027-8424},
	doi = {10.1073/pnas.1921544118},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1921544118https://syndication.highwire.org/content/doi/10.1073/pnas.1921544118http://www.pnas.org/syndication/doi/10.1073/pnas.1921544118},
	author = {Li, Gen K. and Fischer, Woodward W. and Lamb, Michael P. and West, A. Joshua and Zhang, Ting and Galy, Valier and Wang, Xingchen Tony and Li, Shilei and Qiu, Hongrui and Li, Gaojun and Zhao, Liang and Chen, Jun and Ji, Junfeng}
}
@article {2864,
	title = {Active Ooid Growth Driven By Sediment Transport in a High-Energy Shoal, Little Ambergris Cay, Turks and Caicos Islands},
	journal = {Journal of Sedimentary Research},
	volume = {88},
	year = {2018},
	month = {Jun-09-2020},
	pages = {1132 - 1151},
	abstract = {Ooids are a common component of carbonate successions of all ages and present significant potential as paleoenvironmental proxies, if the mechanisms that control their formation and growth can be understood quantitatively. There are a number of hypotheses about the controls on ooid growth, each offering different ideas on where and how ooids accrete and what role, if any, sediment transport and abrasion might play. These hypotheses have not been well tested in the field, largely due to the inherent challenges of tracking individual grains over long timescales. This study presents a detailed field test of ooid-growth hypotheses on Little Ambergris Cay in the Turks and Caicos Islands, British Overseas Territories. This field site is characterized by westward net sediment transport from waves driven by persistent easterly trade winds. This configuration makes it possible to track changes in ooid properties along their transport path as a proxy for changes in time. Ooid size, shape, and radiocarbon age were compared along this path to determine in which environments ooids are growing or abrading. Ooid surface textures, petrographic fabrics, stable-isotope compositions (δ13C, δ18O, and δ34S), lipid geochemistry, and genetic data were compared to characterize mechanisms of precipitation and degradation and to determine the relative contributions of abiotic (e.g., abiotic precipitation, physical abrasion) and biologically influenced processes (e.g., biologically mediated precipitation, fabric destruction through microbial microboring and micritization) to grain size and character. A convergence of evidence shows that active ooid growth occurs along the transport path in a high-energy shoal environment characterized by frequent suspended-load transport: median ooid size increases by more than 100 μm and bulk radiocarbon ages decrease by 360 yr westward along the \~{} 20 km length of the shoal crest. Lipid and 16S rRNA data highlight a spatial disconnect between the environments with the most extensive biofilm colonization and environments with active ooid growth. Stable-isotope compositions are indistinguishable among samples, and are consistent with abiotic precipitation of aragonite from seawater. Westward increases in ooid sphericity and the abundance of well-polished ooids illustrate that ooids experience subequal amounts of growth and abrasion{\textemdash}in favor of net growth{\textemdash}as they are transported along the shoal crest. Overall, these results demonstrate that, in the Ambergris system, the mechanism of ooid growth is dominantly abiotic and the loci of ooid growth is determined by both carbonate saturation and sediment transport mode. Microbes play a largely destructive, rather than constructive, role in ooid size and fabric.},
	issn = {1527-1404},
	doi = {10.2110/jsr.2018.59},
	url = {https://pubs.geoscienceworld.org/sepm/jsedres/article/88/9/1132/559083/Active-Ooid-Growth-Driven-By-Sediment-Transport-in},
	author = {Trower, Elizabeth J. and Cantine, Marjorie D. and Gomes, Maya L. and Grotzinger, John P. and Knoll, Andrew H. and Lamb, Michael P. and Lingappa, Usha and O{\textquoteright}Reilly, Shane S. and Present, Theodore M. and Stein, Nathan and Strauss, Justin V. and Fischer, Woodward W.}
}
