Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key compo...Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and 展开更多
This paper focuses on the interpretations in the analyses of palynofacies and organic geochemistry carried out on a sedimentary profile covering 9542 cal yr BP from a pond located at the mining district from Ametista ...This paper focuses on the interpretations in the analyses of palynofacies and organic geochemistry carried out on a sedimentary profile covering 9542 cal yr BP from a pond located at the mining district from Ametista do Sul, southernmost Brazil. The hydrological isolation renders this pond, located on a hilltop, highly sensitive to climatic change because the water entering in the system is subsidized exclusively by the rainfall. The main goal of this study is to establish relationships between the sedimentary organic record and climatic fluctuations in the Holocene, trying to correlate the alterations in the particulate organic matter with regional climatic changes or perhaps even events on a global scale. Fluctuations in water depth are inferred from the frequency of the autochthonous elements (algae), which predominate in the basal intervals, but tend to decrease progressively toward the top, when begining to alternate periods of high and low frequency with the parautochthonous (spores) and allochthonous (pollen grains) elements, due to changes in the patterns of moisture. Pseudoschizaea seems to have a closer relationship with the spores than with all other algae and can serve as a biological marker of transitional intervals or have some role in the successional process of vegetation. The variety of spores of ferns and pollen grains on the topmost interval indicates increased vegetal diversity, and is probably related to the process of successional evolution of the area. An increased rainfall event detected between 8.6 to 7.4 ka yr BP can be responsible for the beginning of the process of water accumulation in the gossan and sedimentation of the pond and can be related with the “Bond Events”. The saturation level of the pond, in turn, remained relatively constant until 6.8 ka yr BP, when changes in the patterns of moisture make the environment drier and resulted in an intermittent pattern of water depth, currently existing on the site.展开更多
基金The National Natural Science Foundation of China under contract No.41530960
文摘Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and
基金The authors are grateful to the Prefeitura Municipal of Ametista do Sul and to the COOGAMAI(Cooperativa de Garimpeiros do Médio Alto Uruguai)for essential support in field work and to the mine owners for permission to collect the core samplesThis is the result of PhD thesis of the first author at Programa de Pós-Graduacao em Geociencias,Universidade Federal do Rio Grande do Sul,Brazil.GTGM acknowledges a scholarship from Conselho Nacional do Desenvolvimento Científico e Tecnológico(CNPq)of the Brazilian Government.CNPq supported the investigation financially through a project no:401755/2010-0.
文摘This paper focuses on the interpretations in the analyses of palynofacies and organic geochemistry carried out on a sedimentary profile covering 9542 cal yr BP from a pond located at the mining district from Ametista do Sul, southernmost Brazil. The hydrological isolation renders this pond, located on a hilltop, highly sensitive to climatic change because the water entering in the system is subsidized exclusively by the rainfall. The main goal of this study is to establish relationships between the sedimentary organic record and climatic fluctuations in the Holocene, trying to correlate the alterations in the particulate organic matter with regional climatic changes or perhaps even events on a global scale. Fluctuations in water depth are inferred from the frequency of the autochthonous elements (algae), which predominate in the basal intervals, but tend to decrease progressively toward the top, when begining to alternate periods of high and low frequency with the parautochthonous (spores) and allochthonous (pollen grains) elements, due to changes in the patterns of moisture. Pseudoschizaea seems to have a closer relationship with the spores than with all other algae and can serve as a biological marker of transitional intervals or have some role in the successional process of vegetation. The variety of spores of ferns and pollen grains on the topmost interval indicates increased vegetal diversity, and is probably related to the process of successional evolution of the area. An increased rainfall event detected between 8.6 to 7.4 ka yr BP can be responsible for the beginning of the process of water accumulation in the gossan and sedimentation of the pond and can be related with the “Bond Events”. The saturation level of the pond, in turn, remained relatively constant until 6.8 ka yr BP, when changes in the patterns of moisture make the environment drier and resulted in an intermittent pattern of water depth, currently existing on the site.
