Schoon P.L.,Netherlands Institute for Sea Research |
Sluijs A.,Institute of Environmental Biology |
Sinninghe Damste J.S.,Netherlands Institute for Sea Research |
Sinninghe Damste J.S.,University Utrecht |
And 2 more authors.
Paleoceanography | Year: 2011
The middle Paleocene through early Eocene long-term gradual warming was superimposed by several transient warming events, such as the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM2). Both events show evidence for extreme global warming associated with a major injection of carbon into the ocean-atmosphere system, but the mechanisms of carbon injection and many aspects of the environmental response are still poorly understood. In this study, we analyzed the concentration and stable carbon isotopic (δ 13C) composition of several sulfur-bound biomarkers derived from marine photoautotrophs, deposited in the Arctic Ocean at ∼85N, during ETM2. The presence of sulfur-bound biomarkers across this event points toward high primary productivity and anoxic bottom water conditions. The previously reported presence of isorenieratene derivatives indicates euxinic conditions in the photic zone, likely caused by a combination of enhanced primary productivity and salinity stratification. The negative carbon isotope excursion measured at the onset of ETM2 for several biomarkers, ranges between 3‰ and 4.5‰, much larger than the ∼1.4‰ recorded in marine carbonates elsewhere, suggesting substantial enhanced isotopic fractionation by the primary producers likely due to a significant rise in pCO 2. In the absence of biogenic carbonates in the ETM2 section of our core we use coeval planktonic δ 13C from elsewhere to estimate surface water δ 13C in the Arctic Ocean and then apply the relation between isotopic fractionation and pCO 2, originally calibrated for haptophyte alkenones, to three selected organic biomarkers (i.e., S-bound phytane, C 35 hopane, and a C 25 highly branched isoprenoid). This yields pCO 2 values potentially in the range of four times preindustrial levels. However, these estimates are uncertain because of a lack of knowledge on the importance of pCO 2 on photosynthetic isotopic fractionation. Copyright 2011 by the American Geophysical Union. Source
Nierop K.G.J.,University Utrecht |
Speelman E.N.,University Utrecht |
de Leeuw J.W.,University Utrecht |
de Leeuw J.W.,Netherlands Institute for Sea Research |
And 2 more authors.
Organic Geochemistry | Year: 2011
Several studies have reported the presence of large amounts of lignin in ubiquitously occurring species of the freshwater fern Azolla. Molecular analysis using flash pyrolysis and thermally assisted hydrolysis and methylation shows, however, that neither the leaves nor the roots of Azolla contain lignin. Instead, both contain polyphenolic constituents that have a close resemblance to condensed tannins, albeit with a slightly different composition than the common tannins of higher plants. © 2011 Elsevier Ltd. Source
Hasegawa A.,Kumamoto University |
Yanagi U.,Kogakuin University |
Kagi N.,Tokyo Institute of Technology |
Hasegawa K.-I.,Akita Prefectural University |
And 3 more authors.
Journal of Environmental Engineering (Japan) | Year: 2016
Indoor air quality and climate of three temporary emergency housing units in Aso City, Kumamoto Prefecture, have been measured from August 2013 to April 2014 continuously and those results are reported in this paper comparing with those factors in Tohoku region. Outdoor air was introduced during the daytime through the year and carbon dioxide (CO2) concentrations in the three units were lower than 1000 ppm. However, CO2 concentrations were very high during the evening especially with heating and cooling equipments. A mechanical ventilation system for 24-hour ventilation was installed in the toilet and was typically run, however, the air volume can be insufficient or the route of ventilation can be inappropriate. Concentrations of chemical substances in the three units were significantly lower than guideline values and those in Tohoku area. On the other hand, fungal contamination was detected in a number of rooms that had less airflow. Good indoor air quality by the sufficient ventilation and frequent cleaning are required to support victims' health. Source
Yoshino H.,Tohoku University |
Ando N.,Taisei Corporation |
Kensuke H.,Kajima Corporation |
Hasegawa K.,Akita Prefectural University |
And 6 more authors.
Indoor and Built Environment | Year: 2014
In Japan, there is an increase in allergic diseases such as asthma, respiratory symptom, particularly prevailing among the young generation. The reasons why the prevalence is increasing are still not yet well understood. However, it is deemed that indoor environmental factors are one of the essential sources. Therefore, an epidemiology type of survey was investigated on the 4th and 5th grade school children in Japan. The survey was divided into three phases. Phase 1 was a preliminary cross-sectional questionnaire of the prevalence of health problems. Phase 2 was a cross-sectional questionnaire survey on housing characteristics and health. Phase 3 was a field measurement for case control. This paper describes the study protocol and the outcomes from Phase 1. The prevalence of current allergic symptoms was 49.9%. Asthma and rhinitis of the children were 12.5% and 33.3%, respectively. The prevalence of several allergic symptoms among boys was significantly higher than in girls. It indicated that the environmental factors such as pollen, indoor house dust and dust mites could influence allergic symptoms. This survey reveals the ratio of children allergic symptoms in Japan and the possibility of the association between adverse health effect and indoor environmental factors. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. Source
Verbruggen F.,Institute of Environmental Biology |
Heiri O.,Institute of Environmental Biology |
Reichart G.-J.,Organic Geochemistry |
de Leeuw J.W.,Institute of Environmental Biology |
And 3 more authors.
Journal of Paleolimnology | Year: 2010
Stable oxygen isotope measurements on fossil chironomid head capsules from lake sediments show that these chitinous remains can be used to reconstruct past lake water δ18O and, indirectly, past climate change. We examined the impact of chemical pretreatment procedures on the chemical and stable oxygen isotope composition, and morphology of chironomid cuticles. Use of alkali, acids, and sodium chlorite alters the chemical composition and the morphological structure of chironomid cuticles by selective removal of chitin or proteins. Gas chromatograms of pyrolyzates show that NaClO2 causes deproteination, whereas the combined use of HCl and HF results in partial chitin removal. Head capsules pretreated with KOH contained both chitin- and protein-derived moieties, although the concentration of protein was reduced, especially after KOH treatment at high concentration (28%) and temperature (100°C). Scanning electron microscopy confirmed that a proteinaceous matrix is still present in modern and fossil head capsules after KOH treatment. This matrix, however, is largely absent in head capsules pretreated with NaClO2. A change in the proportion of chitin and proteins in our samples was associated with differences in chironomid δ18O values. Our results suggest that deproteination results in a relative increase of chironomid δ18O, whereas removal of chitin leads to decreased δ18O values. We therefore discourage the use of acids or prolonged (≥1 h) exposure to hot alkali (70°C) prior to chironomid δ18O analysis. Chitin purification by sodium chlorite causes significant weight loss, which may preclude down-core chironomid δ18O measurements. Caution and standardization are required when pretreating samples for chironomid δ18O analysis to ensure reliable, comparable, and reproducible results. © 2009 The Author(s). Source