Temperate forests play an important role in the global carbon cycle, and are thought to currently be a sink for atmospheric CO₂. However, we lack understanding of the drivers of forest carbon accumulation and loss, hampering our ability to predict carbon cycle responses to global change. In this study, we...
A series of combined measurements was made at the Naval Air Station North Island (NASNI) Installation Restoration Site 5, Unit 2 during July and August 2013. Combined measurements included CO₂ respiration rate, CO₂ radiocarbon content to estimate chlorinated hydrocarbon (CH) mineralization and a zone of influence (ZOI) model. CO₂ was...
The bivalve Pacific geoduck (Panopea generosa) has been used in the eastern North Pacific Ocean to create proxies for environmental factors such as temperature and oceanographic conditions. This type of research depends upon accurate age determination of Pacific geoducks, which historically was based on shell growth-increment counts. A recent study...
Radiocarbon measurements at ice margin sites and blue ice areas can potentially be used for ice dating, ablation rate estimates and paleoclimatic reconstructions. Part of the measured signal comes from in situ cosmogenic ¹⁴C production in ice, and this component must be well understood before useful information can be extracted...
We report the intercalibration of paleomagnetic secular variation (PSV) and expanded postglacial sediment cores from geographically proximal, but sedimentologically contrasting settings. The objective is to improve relative what can be achieved with either method alone. Core MD99-2269 was taken from north Iceland shelf. Core MD99-2322 was collected from the Kangerlussuaq...
Forest fires contribute a significant amount of CO₂ to the atmosphere each year, and CO₂ emissions from fires are likely to increase under projected conditions of global climate change. In addition to volatilizing aboveground biomass and litter layers, forest fires have a profound effect on belowground carbon (C) pools and...
We present techniques for obtaining large (∼100 L STP) samples of ancient air for analysis of ¹⁴C of methane (¹⁴CH₄) and other trace constituents. Paleoatmospheric ¹⁴CH₄ measurements should constrain the fossil fraction of past methane budgets, as well as provide a definitive test of methane clathrate involvement in large and...
In steep headwater basins of the Oregon Coast Range (OCR), debris flows episodically deliver material from low-order tributary basins to larger catchments. Much of this material is stored in valleys and gradually removed by fluvial processes. Quantifying the transfer of material from hillslopes to mainstem channels is essential in understanding...
Sediment deposit ages inferred from radiocarbon dating of stream bank material were used to estimate residence times of valley-floor deposits in headwater valleys of the Oregon Coast Range, USA. Inherited ages of radiocarbon-dated material, i.e., time between carbon fixation in wood and its incorporation in a sediment deposit, can result...
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Stephen T. Lancaster
Sediment deposit ages inferred from radiocarbon dating of stream bank