A simple method for estimating the influence of eroding soil profiles on atmospheric CO2

This published article is © American Geophysical Union and can found on the publisher's website at http://dx.doi.org/10.1029/2009GB003560Although soil erosion has often been considered a net source of atmospheric carbon (C), several recent studies suggest that erosion serves as a net C sink. We have developed a spreadsheet‐based model of soil organic C dynamics within an eroding profile (Soil Organic Carbon, Erosion, Replacement, and Oxidation (SOrCERO)) that calculates effects of soil organic carbon (SOC) erosion and altered SOC oxidation and production on the net exchange of C between the eroding profile and atmosphere. SOrCERO suggests that erosion can induce a net C sink or source, depending on management practices, the extent to which SOC oxidation and production characteristics change with erosion, and the fate of eroded SOC. Varying these parameters generated a wide range of C source and sink estimates (maximum net source and sink of 1.1/3.1 Pg C yr−1 respectively, applying results globally), highlighting research needs to constrain model estimates. We invite others to download SOrCERO (http://www.kbs.ku.edu/people/staff_www/billings/index.html) to test conceptual models and eroding soil profiles of interest in a consistent, comparable fashion

Fates of Eroded Soil Organic Carbon: Mississippi Basin Case Study

We have developed a mass balance analysis of organic carbon (OC) across the five major river subsystems of the Mississippi (MS) Basin (an area of 3.2 3 106 km2). This largely agricultural landscape undergoes a bulk soil erosion rate of ;480 t·km22·yr21 (;1500 3 106 t/yr, across the MS Basin), and a soil organic carbon (SOC) erosion rate of ;7 t·km22·yr21 (;22 3 106 t/yr). Erosion translocates upland SOC to alluvial deposits, water impoundments, and the ocean. Soil erosion is generally considered to be a net source of CO2 release to the atmosphere in global budgets. However, our results indicate that SOC erosion and relocation of soil apparently can reduce the net SOC oxidation rate of the original upland SOC while promoting net replacement of eroded SOC in upland soils that were eroded. Soil erosion at the MS Basin scale is, therefore, a net CO2 sink rather than a source.This paper is part of ongoing studies by the coauthors to determine the role of landscape erosion and deposition in material fluxes and biogeochemical cycling. Parts of this work have been supported by internal institutional support at CICESE, Emporia State University, Miami University College of Arts and Science, and the Kansas Geological Survey, and by a Kansas NASA EPSCoR grant awarded to R. W. Buddemeier and R. O. Sleezer.We thank the numerous individuals who contributed technical assistance or conceptual support to these efforts. Three reviewers have provided useful critical comments on versions of this manuscript. Of these, we would like to single out Jon Cole, who thoroughly grasped the big picture of what we were advancing and whose summary comment seems worth quoting: ‘‘The idea that soil erosion is a large net sink of atmospheric CO2 is very interesting, well supported by the arguments and data in this paper, and likely to be a huge controversy. This controversy is a good thing, as Martha Stewart might say.’

A modeling tool to evaluate regional coral reef responses to changes in climate and ocean chemistry

This is the published version.We developed a spreadsheet-based model for the use of managers, conservationists, and biologists for projecting the effects of climate change on coral reefs at local-to-regional scales. The COMBO (Coral Mortality and Bleaching Output) model calculates the impacts to coral reefs from changes in average SST and CO2 concentrations, and from high temperature mortality (bleaching) events. The model uses a probabilistic assessment of the frequency of high temperature events under a future climate to address scientific uncertainties about potential adverse effects. COMBO offers data libraries and default factors for three selected regions (Hawai’i, Great Barrier Reef, and Caribbean), but it is structured with user-selectable parameter values and data input options, making possible modifications to reflect local conditions or to incorporate local expertise. Preliminary results from sensitivity analyses and simulation examples for Hawai’i demonstrate the relative importance of high temperature events, increased average temperature, and increased CO2 concentration on the future status of coral reefs; illustrate significant interactions among variables; and allow comparisons of past environmental history with future predictions

Projected Changes to Growth and Mortality of Hawaiian Corals over the Next 100 Years

BACKGROUND: Recent reviews suggest that the warming and acidification of ocean surface waters predicated by most accepted climate projections will lead to mass mortality and declining calcification rates of reef-building corals. This study investigates the use of modeling techniques to quantitatively examine rates of coral cover change due to these effects. METHODOLOGY/PRINCIPAL FINDINGS: Broad-scale probabilities of change in shallow-water scleractinian coral cover in the Hawaiian Archipelago for years 2000-2099 A.D. were calculated assuming a single middle-of-the-road greenhouse gas emissions scenario. These projections were based on ensemble calculations of a growth and mortality model that used sea surface temperature (SST), atmospheric carbon dioxide (CO(2)), observed coral growth (calcification) rates, and observed mortality linked to mass coral bleaching episodes as inputs. SST and CO(2) predictions were derived from the World Climate Research Programme (WCRP) multi-model dataset, statistically downscaled with historical data. CONCLUSIONS/SIGNIFICANCE: The model calculations illustrate a practical approach to systematic evaluation of climate change effects on corals, and also show the effect of uncertainties in current climate predictions and in coral adaptation capabilities on estimated changes in coral cover. Despite these large uncertainties, this analysis quantitatively illustrates that a large decline in coral cover is highly likely in the 21(st) Century, but that there are significant spatial and temporal variances in outcomes, even under a single climate change scenario

Biogeoinformatics of Hexacorallia

Hosted by the Kansas Geological Survey, this Web site contains a suite of databases and related tools for geospatial, taxonomic, and environmental data on hexacorals and related cnidarians. Created as part of the Census of Marine Life through the National Oceanographic Partnership Program, this incredibly comprehensive Web site is "a public information resource of data, interpretation, and methods related to the taxonomy, biogeography, and habitat characteristics or environmental correlates of the Hexacorallia and allied taxa." Available tools and databases are too numerous to list here, but each includes detailed information and instructions. Visitors to the site must register to use site features, but may also preview tools and databases as a guest

WRRCTR No. 65 Tritium Measurement of Natural Waters on Oahu, Hawaii: A Preliminary Interpretation (Sampling Perio: July 1969 to June 1970)

Water samples collected from various surface and sub-surface sources on the island of Oahu were analyzed for tritium levels. Tritium activity levels in twenty-five monthly rainwater samples show a seasonal dependence with a maximum in the summer (18.5 to 23 TU) and a minimum in the winter (12 TU). Samples from two surface-water reservoirs had activities of 13.2 and 19.7 TU reflecting contemporary rainwater which is their major source of recharge. Four streams in the Pearl Harbor area showed "rainwater" tritium levels when sampled at high flow. At low flow, two of the streams had low tritium levels indicating ground-water discharge into the stream, while the tritium activity of the other two streams was conparable to rainwater. Tritium activity higher than that of contemporary rainwater (22-38 TU) was exhibited by samples from two springs which discharge perched water, while samples from three wells and two shafts in the Honolulu area showed very little or no tritium activity. Multiple-depth samples obtained from wells in the Pearl Harbor area showed correlations between tritium activities, depths of sampling, and chloride concentrations.OWRR Project No. A-021-HI , Grant Agreement No. 14-31-0001-3011 The programs and activities described herein were supported in part by funds provided by the United States Department of the Interior as authorized under the Water Resources Act of 1964, Public Law 88-379

WRRCTR No. 53 Tritium and Radiocarbon in Hawaiian Natural Waters: Part I

A field investigation was undertaken to establish the present tritium and radiocarbon activity levels of natural waters found in various parts of the island of Oahu. The instrumentation required for the radiocarbon analysis was assembled and workable procedures were developed. Monthly rainwater samples obtained from rain gages on the Koolau Range contained seasonally fluctuating tritium concentrations which are well in excess of the natural abundance level. Excess concentrations were also found for the tritium and radiocarbon content of surface waters from three separate sources. These excess concentrations are the result of fallout from atmospheric nuclear explosions. Samples from nine tunnels, which tap various Koolau dike compartments, contained tritium activities ranging from the current rainwater levels down to the pre-nuclear explosion levels. Most samples showed radiocarbon activities comparable to pre-explosion atmospheric C02 levels. Two samples, however, showed excess radiocarbon. Samples from wells and shafts tapping basal water in the Honolulu area generally showed little or no tritium and their radiocarbon concentrations were lower than those of the dike-water samples. Makiki, Booth, and Roseapple Springs, which discharge perched water, exhibited tritium levels slightly in excess of the contemporary rain water levels. Nuclear explosion radiocarbon was present at Makiki Spring whereas it was absent at Booth Spring. Correlations between radiocarbon and chloride content were found for samples from Central Oahu and the Pearl Harbor area. The magnitude of both constituents were moreover a function of the distance between the sample source and Pearl Harbor. Three multiple depth samples from well T-133 at Ewa Beach showed very low radiocarbon content. These results can be evidences of radioactive decay of the radiocarbon thus indicating very long residence times of these waters. Exchange reactions between the water-carbonates and the radiocarbon-free aquifer carbonates can lead to the same results however. The discovery of a linear relationship between the radiocarbon activity and chloride contents of these samples indicates that chemical exchange reactions have taken place.OWRR Project No. B-016-HI, Grant Agreement No. 14-31-0001-3271 The programs and activities described herein were supported in part by funds provided by the United States Department of the Interior as authorized under the Water Resources Act of 1964, Public Law 88-379