The temporal distributions of pigment on bio-genic calcareous and terrigenic reef sediments, chlorophyll a, chlorophyll b, chlorophyll c, fuco- xanthin, and porphine concentrations were mea- sured monthly in two sedim...The temporal distributions of pigment on bio-genic calcareous and terrigenic reef sediments, chlorophyll a, chlorophyll b, chlorophyll c, fuco- xanthin, and porphine concentrations were mea- sured monthly in two sediment columns (0 - 15 cm) for one year. Pigment concentrations in-creased significantly during winter (Novem-ber-April) in both sediment types particularly in the upper layers of the sediments. Phytoplankton contributions to organic matter were found to be 8 ± 3 and 6 ± 2% in calcareous and terrigenous sediments respectively. The accumulation and the successive degradation of phytoplankton detritus to inorganic nutrients in calcareous sand may partly sustain the productivity of the coral reef communities which live in nutrient-poor environments.展开更多
According to palaeoclimatic and modern instrumental data,numerous studies have indicated that the Arctic climate has undergone a significant warming during the past 100 years,and this may lead to significant impact on...According to palaeoclimatic and modern instrumental data,numerous studies have indicated that the Arctic climate has undergone a significant warming during the past 100 years,and this may lead to significant impact on the fragile lake ecosystem.In this study,we collected a lake sediment core from the Nylesund of Svalbard and determined the concentrations of four pigments including chlorophyll derivatives,total carotenoids,oscillaxanthin and myxoxanthophyll in the sediments.Combined with other physical and chemical proxies such as calcium carbonate,total organic carbon,biogenic silicon etc.,we have reconstructed the historical changes of lacustrine primary productivity in Ny-lesund,especially for the past 100 years.The results showed that during the period of Little Ice Age（LIA）,the climate was unfavorable for the growth of the lake algae,and thus the lacustrine productivity declined.This result was supported by the relatively low contents of pigment and biogenic silica in the sediments.In contrast,the contents of total organic carbon（TOC） and sediment pigments increased significantly in the upper 5 cm（-1890AD）,reflecting the rapid growth of the lake algae,thus the great increase of lacustrine primary productivity,corresponding to the warming climate after LIA.However,the biogenic silica in the upper sediments still had a relatively low level,and this might be related to the growth competition with other algae species.Over the past 100 years,the ratio of Osc/Myx in the sediments decreased continuously,indicative of durative increase of myxoxanthophyll in blue-green algal pigments,and this might imply that the human activity had enhanced the nutrition level of the lake in the Arctic region.展开更多
Cultural eutrophication caused by nutrient over-enrichment in coastal waters will lead to a cascading set of ecosystem changes and deleterious ecological consequences,such as harmful algal blooms(HABs) and hypoxia.Dur...Cultural eutrophication caused by nutrient over-enrichment in coastal waters will lead to a cascading set of ecosystem changes and deleterious ecological consequences,such as harmful algal blooms(HABs) and hypoxia.During the past two decades since the late 1990s,recurrent large-scale HABs(red tides)and an extensive hypoxic zone have been reported in the coastal waters adjacent to the Changjiang River estuary.To retrieve the history of eutrophication and its associated ecosystem changes,a sediment core was collected from the "red-tide zone" adjacent to the Changjiang River estuary.The core was dated using the^(210)Pb radioisotope and examined for multiple proxies,including organic carbon(OC),total nitrogen(TN),stable isotopes of C and N,and plant pigments.An apparent up-core increase of OC content was observed after the 1970s,accompanied by a rapid increase of TN.The concurrent enrichment of δ^(13)C and increase of the C/N ratio suggested the accumulation of organic matter derived from marine primary production during this stage.The accumulation of OC after the 1970 s well reflected the significant increase of primary production in the red-tide zone and probably the intensification of hypoxia as well.Plant pigments,including chlorophyll a,p-carotene,and diatoxanthin,showed similar patterns of variation to OC throughout the core,which further confirmed the important contribution of microalgae,particularly diatoms,to the deposited organic matter.Based on the variant profiles of the pigments representative of different microalgal groups,the potential changes of the phytoplankton community since the 1970s were discussed.展开更多
文摘The temporal distributions of pigment on bio-genic calcareous and terrigenic reef sediments, chlorophyll a, chlorophyll b, chlorophyll c, fuco- xanthin, and porphine concentrations were mea- sured monthly in two sediment columns (0 - 15 cm) for one year. Pigment concentrations in-creased significantly during winter (Novem-ber-April) in both sediment types particularly in the upper layers of the sediments. Phytoplankton contributions to organic matter were found to be 8 ± 3 and 6 ± 2% in calcareous and terrigenous sediments respectively. The accumulation and the successive degradation of phytoplankton detritus to inorganic nutrients in calcareous sand may partly sustain the productivity of the coral reef communities which live in nutrient-poor environments.
基金supported by the National Natural Science Foundation(Grant Nos.40876096,40606003and 40676004)the young fund for strategetic research of Chinese polar sciences fromCAAA(No.20070202)+1 种基金open research fund from SOA Key Laboratory for Polar Science(KP2007002)special fund for excellent PhD thesis of CAS
文摘According to palaeoclimatic and modern instrumental data,numerous studies have indicated that the Arctic climate has undergone a significant warming during the past 100 years,and this may lead to significant impact on the fragile lake ecosystem.In this study,we collected a lake sediment core from the Nylesund of Svalbard and determined the concentrations of four pigments including chlorophyll derivatives,total carotenoids,oscillaxanthin and myxoxanthophyll in the sediments.Combined with other physical and chemical proxies such as calcium carbonate,total organic carbon,biogenic silicon etc.,we have reconstructed the historical changes of lacustrine primary productivity in Ny-lesund,especially for the past 100 years.The results showed that during the period of Little Ice Age（LIA）,the climate was unfavorable for the growth of the lake algae,and thus the lacustrine productivity declined.This result was supported by the relatively low contents of pigment and biogenic silica in the sediments.In contrast,the contents of total organic carbon（TOC） and sediment pigments increased significantly in the upper 5 cm（-1890AD）,reflecting the rapid growth of the lake algae,thus the great increase of lacustrine primary productivity,corresponding to the warming climate after LIA.However,the biogenic silica in the upper sediments still had a relatively low level,and this might be related to the growth competition with other algae species.Over the past 100 years,the ratio of Osc/Myx in the sediments decreased continuously,indicative of durative increase of myxoxanthophyll in blue-green algal pigments,and this might imply that the human activity had enhanced the nutrition level of the lake in the Arctic region.
基金Supported by the National Basic Research Program of China(973 Program)(No.2010CB428705)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA11020304)+1 种基金the National Natural Science Foundation of China(Nos.41206098,U1406403,41121064)the Open Cruise 2009 for Chinese Offshore Oceanography Research by IOCAS
文摘Cultural eutrophication caused by nutrient over-enrichment in coastal waters will lead to a cascading set of ecosystem changes and deleterious ecological consequences,such as harmful algal blooms(HABs) and hypoxia.During the past two decades since the late 1990s,recurrent large-scale HABs(red tides)and an extensive hypoxic zone have been reported in the coastal waters adjacent to the Changjiang River estuary.To retrieve the history of eutrophication and its associated ecosystem changes,a sediment core was collected from the "red-tide zone" adjacent to the Changjiang River estuary.The core was dated using the^(210)Pb radioisotope and examined for multiple proxies,including organic carbon(OC),total nitrogen(TN),stable isotopes of C and N,and plant pigments.An apparent up-core increase of OC content was observed after the 1970s,accompanied by a rapid increase of TN.The concurrent enrichment of δ^(13)C and increase of the C/N ratio suggested the accumulation of organic matter derived from marine primary production during this stage.The accumulation of OC after the 1970 s well reflected the significant increase of primary production in the red-tide zone and probably the intensification of hypoxia as well.Plant pigments,including chlorophyll a,p-carotene,and diatoxanthin,showed similar patterns of variation to OC throughout the core,which further confirmed the important contribution of microalgae,particularly diatoms,to the deposited organic matter.Based on the variant profiles of the pigments representative of different microalgal groups,the potential changes of the phytoplankton community since the 1970s were discussed.
