A spike of CO₂ in the atmosphere at glacial-interglacial boundaries induced by rapid deposition of manganese in the oceans     

A. MANGINI  A. EISENHAUER  P. WALTER 《Tellus. Series B, Chemical and physical meteorology》1991,43(2):97-105

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Stable isotopes in a stalagmite from NW Sweden document environmental changes over the past 4000 years   总被引：1，自引：0，他引：1  

HANNA S. SUNDQVIST  KARIN HOLMGREN  ERS MOBERG  CHRISTOPH SPÖTL  AUGUSTO MANGINI 《Boreas: An International Journal of Quaternary Research》2010,39(1):77-86

Sundqvist, H. S., Holmgren, K., Moberg, A., Spötl, C. & Mangini, A. 2009: Stable isotopes in a stalagmite from NW Sweden document environmental changes over the past 4000 years. Boreas, 10.1111/j.1502‐3885.2009.00099.x. ISSN 0300‐9483. This study of a 4000‐year‐old stalagmite from Korallgrottan in northwestern Sweden highlights the potentials and challenges when using stable isotopes in stalagmites as climate proxies, as well as the fact that the relationship between climate and proxy may change through time. Both the oxygen and the carbon isotopes display an overall trend of enrichment together with decreasing growth rates over the time period covered by the stalagmite, which is considered a generally cooling period according to current palaeoclimate understanding. The stable isotope records show enriched isotopic values during the, for Scandinavia, comparatively cold period AD 1300–1700 and depleted values during the warmer period AD 800–1000. The indication of a negative relationship between measured δ¹⁸O and surface temperature concurs with earlier reported stalagmite records from regions with a seasonal snow cover and is further supported by the fact that the stalagmite δ¹⁸O record shows general similarities with both regional and hemispheric temperature reconstructions available for the past 500 and 2000 years, respectively. Compared with a stable isotope record of lacustrine carbonates from northern Sweden, however, shifting correlations over time between the two records indicate that a local hydrological change may have taken place at Korallgrottan, or at the lake, compared with around 1000 years ago. The earlier part of the stalagmite δ¹⁸O might thus be influenced, to some extent, by another process than the later part, which means that a negative relationship between δ¹⁸O and surface temperature might not hold for the entire 4000‐year‐old record.  相似文献   

Determination of recent deposition rates in Lake Constance with radioisotopic methods   总被引：3，自引：0，他引：3  

JANUSZ DOMINIK  AUGUSTO MANGINI†  GERMAN MÜLLER 《Sedimentology》1981,28(5):653-677

Sedimentation rates were determined with the ²¹⁰Pb method in eight sediment cores from Lake Constance. The rate of deposition in the main basin (Obersee) varies from about 0.06 g cm^?2 y^?1 in the central part to 0.13 g cm^?2 y^?1 in the eastern part of the lake and then increases rapidly towards the Rhine delta. In the central lake area the rate of deposition has been approximately constant since 1900, and dating with the ²¹⁰Pb method is in good agreement with sedimentological observations. In the Konstanzer Trichter area, the deposition rate has been increasing since about 1955 as a result of eutrophication and subsequent high carbonate production. Dating with ¹³⁷Cs is fairly accurate for sediments deposited at a high rate, but is questionable for slowly accumulating ones. A positive correlation of ²¹⁰Pb fluxes and sedimentation rates indicates that ²¹⁰Pb flux into sediments follows the distribution pattern of solids. ²¹⁰Pb profiles in four sediment cores interpreted in terms of a constant flux model display synchronous fluctuations of the sedimentation rate; however, their relation to long-range particulate input variations remains to be proved. Sedimentation rates determined with the ²¹⁰Pb method were used to calculate recent nutrient and heavy metal fluxes. Anthropogenic fluxes of Zn and Pb are in the same range of magnitude as in other polluted areas in Europe and America.  相似文献