Variation in carbon content of tropical tree species from Ghana

Most research on carbon content of trees has focused on temperate tree species with little information existing on the carbon content of tropical tree species. This study investigated the variation in carbon content of selected tropical tree species and compared carbon content of Khaya spp from two ecozones in Ghana. Allometric equations developed for mixed-plantation stands for wet evergreen forest verified the expected strong relationship between tree volumes and dbh (r2>0.93) and volume and dbh2×height (r2>0.97). Carbon concentration, wood density and carbon content differed significantly among species. Volume at age 12 ranged from 0.01 to 1.04 m3 per tree, and wood density was highly variable among species, ranging from 0.27 to 0.76 g cm-3. This suggests that species specific density data is critical for accurate conversion of volumes derived from allometric relationships into carbon contents. Significant differences in density of Khaya spp existed between the wet and moist semi-deciduous ecozones. The baseline species-level information from this study will be useful for carbon accounting and development of carbon sequestration strategies in Ghana and other tropical African countries.

Recent Increase in Black Carbon Concentrations from a Mt. Everest Ice Core Spanning 1860-2000 AD

A Mt. Everest ice core spanning 1860-2000 AD and analyzed at high resolution for black carbon (BC) using a Single Particle Soot Photometer (SP2) demonstrates strong seasonality, with peak concentrations during the winter-spring, and low concentrations during the summer monsoon season. BC concentrations from 1975-2000 relative to 1860-1975 have increased approximately threefold, indicating that BC from anthropogenic sources is being transported to high elevation regions of the Himalaya. The timing of the increase in BC is consistent with BC emission inventory data from South Asia and the Middle East, however since 1990 the ice core BC record does not indicate continually increasing BC concentrations. The Everest BC and dust records provide information about absorbing impurities that can contribute to glacier melt by reducing the albedo of snow and ice. There is no increasing trend in dust concentrations since 1860, and estimated surface radiative forcing due to BC in snow exceeds that of dust in snow. This suggests that a reduction in BC emissions may be an effective means to reduce the effect of absorbing impurities on snow albedo and melt, which affects Himalayan glaciers and the availability of water resources in major Asian rivers. Citation: Kaspari, S. D., M. Schwikowski, M. Gysel, M. G. Flanner, S. Kang, S. Hou, and P. A. Mayewski (2011), Recent increase in black carbon concentrations from a Mt. Everest ice core spanning 1860-2000 AD, Geophys. Res. Lett., 38, L04703, doi: 10.1029/2010GL046096.

(Figure 2) Organic carbon content, stable isotope ratios, TEX86 index and sea surface temperature reconstruction for the early Aptian of ODP Hole 198-1207B

The Cretaceous has long been recognized as a time when greenhouse conditions were fueled by elevated atmospheric CO2 and accompanied by perturbations of the global carbon cycle described as oceanic anoxic events (OAEs). Yet, the magnitude and frequency of temperature change during this interval of warm and equable climate are poorly constrained. Here we present a high-resolution record of sea-surface temperatures (SSTs) reconstructed using the TEX86 paleothermometer for a sequence of early Aptian organic-rich sediments deposited during the first Cretaceous OAE (OAE1a) at Shatsky Rise in the tropical Pacific. SSTs range from ~30 to ~36 °C and include two prominent cooling episodes of ~4 °C. The cooler temperatures reflect significant temperature instability in the tropics likely triggered by changes in carbon cycling induced by enhanced burial of organic matter. SST instability recorded during the early Aptian in the Pacific is comparable to that reported for the late Albian-early Cenomanian in the Atlantic, suggesting that such climate perturbations may have recurred during the Cretaceous with concomitant consequences for biota and the marine environment.

Radiocarbon dating, sedimentation rate, granulometry and organic carbon content of ODP Leg 182 sites

This data report presents sedimentological (grain size) and geochemical (X-ray diffraction, total organic carbon, accelerator mass spectrometry radiocarbon, and percent carbonate) information obtained from the western transect (Sites 1132, 1130, and 1134) and the eastern transect (Sites 1129, 1131, and 1127) in the Great Australian Bight during Leg 182. The purpose is to quantify changing rates of sediment accumulation and changes in sediment type from the late Pleistocene and Holocene, in order to relate these changes to the well-known sea level curve that exists for this time frame. Ultimately, these data can be used to more effectively interpret lithologic variations deeper in the Pleistocene succession, which most likely represent orbitally forced sea level events.

Total organic carbon content and isorenieratene concentrations from three holes of ODP Leg 160

Carotenoids were analysed in ca. 1-cm thick subsamples of three laterally time-equivalent sapropels from a west-east transect of the eastern Mediterranean Basin to study euxinic periods during Pliocene sapropel formation. The amount of intact isorenieratene (summed all-trans and cis isomers), ranged from non-detectable at the base and top of a sapropel up to 140 µg/g sediment in the central parts. Isorenieratene accumulation rates at the central and western site are remarkably similar and increase sharply to levels of up to 3.0 mg/m**2/ yr in the central part of the sapropel and then drop to low levels. This pattern indicates an expansion of euxinic conditions reaching into the photic zone, followed by deepening of the chemocline during deposition of this Pliocene sapropel. The sapropel from the easternmost site of the basin, which contains less organic carbon, shows much lower isorenieratene accumulation rates and even absence of isorenieratene in the central part of the sapropel. Ba/Al ratios indicate enhanced palaeoproductivity during sapropel formation, supporting previously proposed models, according to which increased productivity is the driving force for the generation of euxinic conditions.

Time series of black carbon aerosol measurements from Neumayer Station, 1999-2011

Continuous black carbon (BC) observations were conducted from 1999 through 2009 by an Aethalometer (AE10) and from 2006 through 2011 by a Multi-Angle Absorption Photometer (MAAP) at Neumayer Station (NM) under stringent contamination control. Considering the respective observation period, BC concentrations measured by the MAAP were somewhat higher (median ± standard deviation: 2.1 ± 2.0 ng/m**3) compared to the AE10 results (1.6 ± 2.1 ng/m**3). Neither for the AE10 nor for the MAAP data set a significant long-term trend could be detected. Consistently a pronounced seasonality was observed with both instruments showing a primary annual maximum between October and November and a minimum in April with a maximum/minimum ratio of 4.5/1.6 = 3.8 and 2.7/0.64 = 4.2 for the MAAP and AE10 data, respectively. Occasionally a secondary summer maximum in January/February was visible. With the aim to assess the impact of BC on optical properties of the aerosol at NM, we evaluated the BC data along with particle scattering coefficients measured by an integrating nephelometer. We found the mean single scattering albedo of w550 = 0.992 ± 0.0090 (median: 0.994) at a wavelength of 550 nm with a range of values from 0.95 to 1.0.

Stable carbon and oxygen isotopes of foraminifera fand carbon content of ODP Leg 107 holes

High-resolution bio- and chemostratigraphy of an earliest Pliocene section from ODP Site 652 indicates that postflood paleoceanographic conditions in the Tyrrhenian Sea can be sub-divided into two discrete intervals. The first is manifested by an acme of Sphaeroidinellopsis spp., increasing carbonate contents, and a progressive decrease upsection in both the d13C and dl8O values of the planktonic foraminifera. The lower part of the acme interval contains unusual surface-to-bottom water isotope gradients suggesting a stratification of two water masses. Normal gradients in the upper part of the acme interval suggest a well-mixed water body. Between the end of the acme interval and the MP11/MP12 boundary, denoted by the first occurrence (F.O.) of Globorotalia margaritae, a migrational first appearance, there was a catastrophic collapse of the gradient marking an onset of the second post-flood interval. The disintegration of habitable conditions is suggested by a sharp decrease in carbonate content and the disappearance of the benthonic assemblage, which is subsequently replaced predominantly by Uvigerinapygmea, indicative of cold, low-oxygenated bottom waters. The introduction of benthonic species denoting well-oxygenated bottom conditions occurs within the lower MP12 zone. Superimposed on these overall trends are shorter term, warm-cold cycles, which are interpreted as orbitally induced, climatic fluctuations. Correlative studies of the less complete earliest Pliocene sections from ODP Holes 653B and 654A confirm these interpretations. A scenario derived from an integration of all the stratigraphic data indicates that normal paleoceanographic conditions were operating in the Tyrrhenian Sea only approximately 250,000 yr after the cessation of Messinian evaporative conditions at the Miocene/Pliocene boundary. The post-flood interval is marked by an initial period of gradual infilling, the Sphaeroidinellopsis spp. acme interval, followed by a disintegration of oceanographic conditions and a second recovery period. A sudden influx of cold, deep Atlantic waters into the Tyrrhenian Sea, resulting from a major tectonic break in the Gibraltar sill, may have caused this catastrophic reversal in the orderly recovery of normal paleoceanographic conditions in the post-flood period.