@article {2443,
	title = {Linking lithology and land use to sources of dissolved and particulate organic matter in headwaters of a temperate, passive-margin river system},
	journal = {Geochimica Et Cosmochimica Acta},
	volume = {71},
	year = {2007},
	note = {30},
	month = {Sep},
	pages = {4233-4250},
	abstract = {A number of rivers have been found to transport highly aged organic matter [OM]; however, the sources of this aged material remain a matter of debate. One potential source may be erosion and weathering of headwater lithologies rich in ancient sedimentary OM. In this study, waters, suspended particulates, streambed sediments, rocks and soils from fourteen small headwater watersheds of a mid-size, temperate, passive margin river were sampled and characterized by Delta C-14, delta C-13, and POC/TPN ratios to identify sources of particulate and dissolved OM delivered to the river mainstem. These headwater sites encompass a range in lithology (OM-rich shales, OM-lean carbonate/mudstone facies, and OM-free crystalline rocks) and land use types (forested and agricultural), and allow investigation of the influence of agriculture and bedrock types on stream OM characteristics. Streams draining large areas of both agricultural land use and OM-rich lithology contain particulate OM [POM] that is more C-14-depleted than streams draining forested, shale-free watersheds. However, this is not sufficient to account for the significantly lower Delta C-14-POC measured in the river mainstern. Dissolved OM [DOM] Delta C-14 are in all cases enriched compared to POM from the same stream, but are otherwise highly variable and unrelated to either land use or lithology. POC/TPN ratios were likewise highly variable. POC and DOC delta C-13 signatures were similar across all watersheds. Based on isotope mass balance, C-14-free fossil OM sources contribute 0-12\% of total stream POM. Although these results do not unequivocally separate the influences of land use and lithology, watershed coverage by shale and agriculture are both important controls on stream A Delta C-14-POC. Thus export of aged, particle-associated OM may be a feature of river systems along both passive and active continental margins. (C) 2007 Elsevier Ltd. All rights reserved.},
	keywords = {ATCHAFALAYA RIVER, ATMOSPHERIC O-2, BLACK SHALE, continental-shelf, GULF-OF-MEXICO, marine-sediments, MINERAL, SPACE-TIME CLIMATE, STABLE-ISOTOPES, surface sediments, SURFACES},
	isbn = {0016-7037},
	doi = {10.1016/j.gca.2007.06.056},
	author = {Longworth, B. E. and Petsch, S. T. and Raymond, P. A. and Bauer, J. E.}
}
@article {2003,
	title = {Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {6},
	year = {2005},
	note = {909pwTimes Cited:17
Cited References Count:21
},
	month = {Mar 18},
	abstract = {We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC D 14 C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC delta(13)C signature of the river end-member (-11\%) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (<= 10\%) of organic matter remineralization in the mesohaline region. The POC Delta(14)C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine-derived POC.},
	keywords = {accumulation, amazon, C-14, carbon cycling, CO2, continental-shelf, poc, radiocarbon, river system, Sediment, total co(2), water},
	isbn = {1525-2027},
	doi = {10.1029/2004GC000842},
	author = {Druffel, E. R. M. and Bauer, J. E. and Griffin, S.}
}
