Sea surface temperature （SST） proxies including B/Ca, Mg/Ca, St/Ca, U/Ca and δ180 were analyzed in the skeleton of a Porites coral collected from the Zhujiang River （Pearl River） Estuary （ZRE）. These geochemica...Sea surface temperature （SST） proxies including B/Ca, Mg/Ca, St/Ca, U/Ca and δ180 were analyzed in the skeleton of a Porites coral collected from the Zhujiang River （Pearl River） Estuary （ZRE）. These geochemical proxies are influenced by river runoff and this area of the northern South China Sea is strongly affected by seasonal freshwater floods. We assessed the robustness of each SST proxy through comparison with the local instrumental SST. Coral St/Ca shows the highest correlation with SST variations （r2=0.59）, suggesting St/Ca is the most robust SST proxy. In contrast, coral δ180 （r2=0.46）, B/Ca （r2=0.43） and U/Ca （r2=0.41） ratios were only moderately correlated with SST variations, suggesting that they are disturbed by some other factors in addition to SST. The poor correlation （r2=0.27） between SST and Mg/Ca indicates that Mg/Ca in coral skeletons is not a simple function of SST variations. This may ultimately limit the use of Mg/Ca as a coral paleothermometer.展开更多
Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium(Cr), ...Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium(Cr), copper(Cu), molybdenum(Mo), manganese(Mn), lead(Pb), tin(Sn), titanium(Ti), vanadium(V), and yttrium(Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea(SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.展开更多
Recently found materials indicate that the steppe mammoth, Mammuthus trogontherii, survived in northern China into the late Pleistocene. East Asia is the key area of mammoth evolution after the initial radiation of ea...Recently found materials indicate that the steppe mammoth, Mammuthus trogontherii, survived in northern China into the late Pleistocene. East Asia is the key area of mammoth evolution after the initial radiation of early forms out of Africa and into Eurasia at the beginning of the late Pliocene (c. 3.5–3.0 Ma). M. rumanus, M. meridionalis, M. trogontherii, and M. primige- nius probably formed a continuous and transitional evolutionary lineage within the pan-Eurasian mammoth radiation in East Asia. Each speciation event of the Eurasian mammoths was followed by a rapid and large-scale dispersal event: out of East Asia. Allopatric speciation is the main speciation pattern of Mammuthus. The climatic vacillation was severe and frequent in East Asia from the early part of early Pleistocene (c. 2.6 Ma) onward, which probably brought about successive speciation in East Asia and the subsequent dispersal of the mammoths.展开更多
基金The National Basic Research Program(973 program) of China under contract No.2013CB956104the National Natural Science Foundation of China under contract Nos 41106054,41306109 and 41476038
文摘Sea surface temperature （SST） proxies including B/Ca, Mg/Ca, St/Ca, U/Ca and δ180 were analyzed in the skeleton of a Porites coral collected from the Zhujiang River （Pearl River） Estuary （ZRE）. These geochemical proxies are influenced by river runoff and this area of the northern South China Sea is strongly affected by seasonal freshwater floods. We assessed the robustness of each SST proxy through comparison with the local instrumental SST. Coral St/Ca shows the highest correlation with SST variations （r2=0.59）, suggesting St/Ca is the most robust SST proxy. In contrast, coral δ180 （r2=0.46）, B/Ca （r2=0.43） and U/Ca （r2=0.41） ratios were only moderately correlated with SST variations, suggesting that they are disturbed by some other factors in addition to SST. The poor correlation （r2=0.27） between SST and Mg/Ca indicates that Mg/Ca in coral skeletons is not a simple function of SST variations. This may ultimately limit the use of Mg/Ca as a coral paleothermometer.
基金Supported by the National Basic Research Program of China(973 Program)(No.2013CB956103)the National Science Foundation of China(Nos.41306109,41476038)
文摘Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium(Cr), copper(Cu), molybdenum(Mo), manganese(Mn), lead(Pb), tin(Sn), titanium(Ti), vanadium(V), and yttrium(Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea(SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.
基金Supported by Knowledge Innovation Project of the Chinese Academy of Sciences(Grant No.KZCX2-YW-318)National Basic Research Program of China(Grant No.2007CB815905)+1 种基金National Natural Science Foundation of China(Grant No.40830852)the Australian Research Council(Grant No.DP0773081)
基金the Knowledge Innovation Project of the Chinese Academy of Sci-ences (Grant No. KZCX2-YW-318)the National Natural Science Foundation of China (Grant No. 40572102)+1 种基金the Ministry of Science and Technology of China (Grant No. 2006BAB19B03)the Sino-Australia Special Collaboration Funds (Grant Nos. 4061120030 and CH050099)
基金supported by Key Knowledge Innovation Project of Chinese Academy of Sci-ences (Grant No. KJCX2-YW-106)National Basic Research Program of China (Grant No. 2006CB806400)
文摘Recently found materials indicate that the steppe mammoth, Mammuthus trogontherii, survived in northern China into the late Pleistocene. East Asia is the key area of mammoth evolution after the initial radiation of early forms out of Africa and into Eurasia at the beginning of the late Pliocene (c. 3.5–3.0 Ma). M. rumanus, M. meridionalis, M. trogontherii, and M. primige- nius probably formed a continuous and transitional evolutionary lineage within the pan-Eurasian mammoth radiation in East Asia. Each speciation event of the Eurasian mammoths was followed by a rapid and large-scale dispersal event: out of East Asia. Allopatric speciation is the main speciation pattern of Mammuthus. The climatic vacillation was severe and frequent in East Asia from the early part of early Pleistocene (c. 2.6 Ma) onward, which probably brought about successive speciation in East Asia and the subsequent dispersal of the mammoths.
