@conference {1547, title = {14C and 13C isotopic characterization of organic carbon in surface waters of the South Atlantic Bight}, booktitle = {ASLO Aquatic Sciences Meeting}, year = {2007}, note = {id: 1026}, month = {2007}, address = {Santa Fe, NM}, author = {De Alteris, J. A. and Bauer, J. E. and Perkey, D. W. and Keesee, E. J. and Cai, W. J.} } @conference {1824, title = {Variability of major carbon pools in the Mississippi River: importance of tributary inputs and regional land use on carbon and organic matter biogeochemistry}, booktitle = {ASLO Aquatic Sciences Meeting}, year = {2007}, note = {id: 484}, month = {2007}, address = {Santa Fe, NM}, author = {Perkey, D. W. and Bauer, J. E. and Keesee, E. J.} } @conference {1622, title = {Elemental and isotopic characterization of organic matter and carbon in the South Atlantic bight, a net heterotrophic ocean margin}, booktitle = {Ocean Sciences Meeting}, year = {2006}, note = {id: 481}, month = {2006}, address = {Honolulu, HI}, author = {De Alteris, J. and Bauer, J. E. and Perkey, D. W. and Keesee, E. J. and Cai, W. J.} } @article {932, title = {Geomorphologic controls on the age of particulate organic carbon from small mountainous and upland rivers}, journal = {Global Biogeochemical Cycles}, volume = {20}, year = {2006}, note = {082xbTimes Cited:78Cited References Count:77}, month = {Sep 9}, pages = {1-11}, abstract = {To assess the role that erosion processes play in governing the character of particulate organic carbon (POC) discharged from small mountainous and upland rivers, a suite of watersheds from Oregon, California, and New Zealand was investigated. The rivers share similar geology, tectonic setting, and climate, but have sediment yields that range over 3 orders of magnitude. The (14)C age of the POC loads is highly correlated with sediment yield. Carbon isotope mass balances reveal that the rivers carry bimodal mixtures of modern-plant-and ancient-rock-derived OC. At lower yields, modern plant OC dominates the material delivered to the river by sheetwash and shallow landsliding. With increasing yield, a progressively larger part of the POC is contributed directly from bedrock erosion via deep gully incision. Our results support the inference that active margin watersheds are important sources of aged POC to the ocean.}, keywords = {14C, kerogen recycling, particulate organic carbon}, issn = {0886-6236}, doi = {10.1029/2005GB002677}, author = {Leithold, E. L. and Blair, N. E. and Perkey, D. W.} } @article {603, title = {Sedimentation and carbon burial on the northern California continental shelf: the signatures of land-use change}, journal = {Continental Shelf Research}, volume = {25}, year = {2005}, note = {894cyTimes Cited:29Cited References Count:109}, month = {Feb}, pages = {349-371}, abstract = {The burial of organic carbon (OC) on continental margins is strongly coupled to the supply and accumulation of inorganic mineral particles. It follows that carbon burial on the margins should be impacted by changes in riverine sediment delivery, yet these impacts have not been well documented. In this study, an similar to2000-year record of sedimentation and carbon burial on the continental shelf offshore from the Eel River in northern California was examined. The record reveals a 6-11-fold increase in the rate of sediment accumulation on the mid-shelf beginning about 1955, and a concomitant decrease in grain size and increase in flood-layer preservation. At the same time. the age of buried wood fragments abruptly decreased and their stable carbon isotopic composition became enriched in C-13. We argue that these changes can be explained largely as the result of altered land use in the Eel watershed during the past century and its impacts on shelf sediment dispersal processes.Sedimentary OC on the Eel shelf consists primarily of discrete wood fragments associated with coarse-silt- and sandsized particles, and of organic matter strongly bound to clay-sized mineral grains. The clay fraction is a particularly sensitive recorder of environmental change in the Eel system. Above the 1995 horizon, the clay fraction shows an abrupt decrease in OC concentration and loading (OC content normalized to particle surface area) attendant with the increased accumulation rate. Kerogen carbon constitutes a relatively constant proportion of the clay-associated OC throughout the similar to2000-year record. Increases in mass wasting and input of bedrock material following the onset of intensive industrial logging in the Eel watershed may have resulted in a lower loading of terrestrial plant OC in the clay fraction deposited after 1955 as suggested by isotopic mass balance calculations.The Eel River is representative of small mountainous watersheds worldwide that deliver a major portion of the sediment and carbon flux to the margins and that have been strongly impacted by land-use change during the past century. Our results suggest that such changes leave a distinctive mark in both the sedimentological and geochemical records preserved offshore. (C) 2004 Elsevier Ltd. All rights reserved.}, issn = {0278-4343}, doi = {10.1016/j.csr.2004.09.015}, author = {Leithold, E. L. and Perkey, D. W. and Blair, N. E. and Creamer, T. N.} } @article {999, title = {The persistence of memory: The fate of ancient sedimentary organic carbon in a modern sedimentary system}, journal = {Geochimica Et Cosmochimica Acta}, volume = {67}, year = {2003}, note = {634jvTimes Cited:143Cited References Count:63}, month = {Jan}, pages = {63-73}, abstract = {The cycle of organic carbon burial and exhumation moderates atmospheric chemistry and global climate over geologic timescales. The burial of organic carbon occurs predominantly at sea in association with clay-sized particles derived from the erosion of uplifted continental rocks. It follows that the history of the fine-grained particles on land may bear on the nature of the organic carbon buried. In this study, the evolution of clay-associated organic matter was followed from bedrock source to the seabed in the Eel River sedimentary system of northern California using natural abundance C-13 and C-14 tracers. Approximately half of the fine-grained organic carbon delivered to the shelf is derived from ancient sedimentary organic carbon found in the uplifted Mesozoic-Tertiary Franciscan Complex of the watershed. The short residence time of friable soils on steep hill slopes, coupled with rapid sediment accumulation rates on the shelf-slope, act to preserve the ancient organic carbon. A comparable quantity of modem organic carbon is added to particles in the watershed and on the shelf and slope. The bimodal mixture of ancient and modem C in soils and sediments may be characteristic of many short, mountainous rivers. If the Eel River chemistry is typical of such rivers, more than 40 Tg of ancient organic C may be delivered to the world{\textquoteright}s oceans each year. A flux of that magnitude would have a significant influence on marine and global C-cycles. Copyright (C) 2003 Elsevier Science Ltd.}, issn = {0016-7037}, doi = {10.1016/S0016-7037(02)01043-8}, author = {Blair, N. E. and Leithold, E. L. and Ford, S. T. and Peeler, K. A. and Holmes, J. C. and Perkey, D. W.} }