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Barium to calcium (Ba/Ca) ratio in corals has been considered as a useful geochemical proxy for upwelling, river flood and other
oceanic processes. However, recent studies indicated that additional environmental or biological factors can influence the incorporation
of Ba into coral skeletons. In this study, Ba/Ca ratios of two Porites corals collected from Daya Bay, northern South China Sea were
analyzed. Ba/Ca signals in the two corals were ‘anomalous’ in comparison with Ba behaviors seen in other near-shore corals influenced
by upwelling or riverine runoff. Our Ba/Ca profiles displayed similar and remarkable patterns characterized by low and randomly
fluctuating background signals periodically interrupted by sharp and large synchronous peaks, clearly indicating an environmental
forcing. Further analysis indicated that the Ba/Ca profiles were not correlated with previously claimed environmental factors such as
precipitation, coastal upwelling, anthropogenic activities or phytoplankton blooms in other areas. The maxima of Ba/Ca appeared to
occur in the period of Sr/Ca maxima, coinciding with the winter minimum temperatures, which suggests that the anomalous high
Ba/Ca signals were related to winter-time low sea surface temperature. We speculated that the Ba/Ca peaks in corals of the Daya Bay
were most likely the results of enrichment of Ba-rich particles in their skeletons when coral polyps retracted under the stresses of
anomalous winter low temperatures. In this case, Ba/Ca ratio in relatively high-latitude corals can be a potential proxy for tracing the
low temperature stress. 相似文献
665.
Feng Qin Shujuan Wang Inna Kim Hallvard F. Svendsen Changhe Chen 《International Journal of Greenhouse Gas Control》2011,5(3):405-412
A reaction calorimeter was used to determine the enthalpies of absorption of CO2 in aqueous ammonia and in aqueous solutions of ammonium carbonate at temperatures of 35–80 °C. The heat of absorption of CO2 with 2.5 wt% aqueous ammonia solution was found to be about 70 kJ/mol CO2, which is lower than that with MEA (around 85 kJ/mol) at 35 and 40 °C. The value decreases with increased loading, but not to as low a value as expected by the carbonate–bicarbonate reaction (26.88 kJ/mol). The enthalpy of absorption of CO2 in aqueous ammonia at 60 and 80 °C decreases with loadings at first, then increases between 0.2 mol CO2/mol NH3 and 0.6 mol CO2/mol NH3, and then decreases again. The behavior of the heat of absorption of CO2 in 10 wt% ammonium carbonate solution was found to be the same as that of aqueous ammonia at loadings above 0.6 mol CO2/mol NH3. The heat of absorption increases with increasing temperature. The heats of absorption are directly related to the extent of the various reactions with CO2 and can be assessed from the species variation in the liquid phase. 相似文献
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Occurrence, distribution, and source of polybrominated diphenyl ethers in soil and leaves from Shenzhen Special Economic Zone, China 总被引:2,自引:0,他引:2
Pei-Heng Qin Hong-Gang Ni Yang-Sheng Liu Ye-Hong Shi Hui Zeng 《Environmental monitoring and assessment》2011,174(1-4):259-270
Polybrominated diphenyl ethers (PBDEs) were measured in soil and three plant species samples taken at different land use areas in Shenzhen China. The concentrations of ??7BDEs (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) and BDE-209 in the surface soils ranged from 0.23 to 271 and 8.9 to 5,956 ng/g dry weight (dw), respectively. These figures are comparable to that in the soils of electronic waste dismantling sites. BDE-209 was the predominant congener (contributes 85?C99% of ??8PBDEs (??7PBDEs plus BDE-209)) in soils. The regression slopes of total organic carbon and individual BDE congeners were rather gentle, indicating that factors other than soil organic matter regulated the soil concentrations. Proximity to sources of deposition processes might be the major factors. In the plant leaves, ??7BDEs and BDE-209 concentrations ranged from 1.29 to 5.91 and 5.49 to 28.2 ng/g dw, respectively. BDE-209 is also the dominant component, but the contribution was much lower compared with that in soils. Bauhinia purpurea Linn. and Michelia alba DC. show some similarities on the uptake of PBDEs, while Ficus microcarpa var. pusillifolia is different from them. The correlations between plant leaf concentrations and predicted gaseous concentrations were moderate, indicating that gaseous concentration did not influence the leaf concentration significantly. 相似文献
669.
Shou-Qing Liu Shi Cheng Li Luo Hong-Ying Cheng Song-Jun Wang Shuai Lou 《Environmental Chemistry Letters》2011,9(1):31-35
Rhodamine B can be degraded using Prussian blue as a photo-Fenton like reagent under λ > 420 nm visible irradiation. Kinetic
studies show ln(C
o/C
t
) is linearly proportional to the reaction time during the photo-degradation process; thus, the degradation reaction obeys
a pseudo-first order kinetic law. It is very interesting that the presence of salinity such as 0.1 M KCl can speed up greatly
the degradation rate: the time to achieve 90.0% degradation ratio is shortened from 120.0 to 40.0 min under comparable conditions,
which is very useful in the treatment of wastewaters with high content of salinity. 相似文献
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