Algae play a crucial role in the evolution of earth and life on earth,and also the cycle of matter.With its unique physiological and ecological properties and strong reproductive capacity,algae deeply influence the fo...Algae play a crucial role in the evolution of earth and life on earth,and also the cycle of matter.With its unique physiological and ecological properties and strong reproductive capacity,algae deeply influence the formation and development of karst.During the formation of tufa landscapes in Huanglong Scenic Area,the coloration,precipitation and corrosion of algae acting on tufa always concordantly exist.The algae living in water add gay colors to the tufa landscapes.The carbonate precipitation facilitated by algae is an important biological cause of the formation of tufa.As the external environmental conditions change,for instance,the shortage of karst water in tufa landscapes,the coloration and powerful corrosion of algae will stand out,which will badly affect the development and visual value of tufa landscapes.By studying the functions of algae in the tufa landscapes of Huanglong Scenic Area,this research was to provide scientific basis for the future study and protection of tufa landscapes.展开更多
Using shotgun sequencing data, the complete sequences of chloroplast 16S rRNA and tufA genes were acquired from native specimens of Bryopsis hypnoides (Qingdao, China). There are two group I introns in the 16S rRNA ge...Using shotgun sequencing data, the complete sequences of chloroplast 16S rRNA and tufA genes were acquired from native specimens of Bryopsis hypnoides (Qingdao, China). There are two group I introns in the 16S rRNA gene, which is structurally similar to that of Caulerpa sertularioides (Bryopsidales, Chlorophyta). The chloroplast-encoded tufA gene sequence is 1 230 bp long, very AT-rich (61.5%), and is similar to previously published 16S rRNA sequences of bryopsidinean algae. Phylogenetic analyses based on chloroplast 16S rRNA and tufA gene sequence data support previous hypotheses that the Bryopsidineae, Halimedineae, and Ostreobidineae are three distinct lineages. These results also confirmed the exclusion of Avrainvillea from the family Udoteaceae. Phylogenetic analyses inferred that the genus Bryopsis as sister to Derbesia; however, this clade lacked robust nodal support. Moreover, the phylogenetic tree inferred from rbcL GenBank sequences, combined with the geographical distributions of Bryopsis species, identified a strongly supportive clade for three differently distributed Asian Bryopsis species. The preliminary results suggesting that these organisms are of distinct regional endemism.展开更多
The paper presents an analysis of characteristic karst tufa from Guangxi, China, which has not been studied before. A comparison with tufa from Dinaric Karst of Croatia is discussed in view of the C-type climate. The ...The paper presents an analysis of characteristic karst tufa from Guangxi, China, which has not been studied before. A comparison with tufa from Dinaric Karst of Croatia is discussed in view of the C-type climate. The major mineral is calcite. Minor minerals are quartz and dolomite, depending on location. The content of calcium carbonate varies from 65% to 92%, and that of magnesium carbonate from 0.03% to 1.77%. Among other elements, the most abundant are Fe, from 0.02% to 1.50%, and Ti, from 0.15% to 0.27%. Many other trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, Hg and Pb) are also present. Specific activity of radionuclides 40K, 232Th, 137Cs, 226Ra and 238U varies from sample to sample. Concentration of U in tufa is close to that reported for sedimentary carbonate. Low concentration of 137Cs indicates that this part of the world was not exposed to nuclear explosions. The concentration of 226Ra is the highest in Mashan County. The ratio 238U/226Ra (0.21-0.71) in tufa from Mashan County is significantly lower than the theoretical value of 1. In 5 of the 11 studied samples, stable isotopes δ13C and δ18O were analyzed. They were dated by means of the 14C method. One tufa sample originated in the Pleistocene and the others in the Holocene. Because all of the tufa samples contain traces of Na and K, and K < Na, the tufa from Guangxi belong to the CO2-outgassing 'N' type according to the classification of Liu and He (1994).展开更多
Wujiangdu Hydropower Station of Guizhou is one of the biggest hydroelectric projects built in karst areas of China. It has a dam 165 m high, with a capacity of 630,000 kW. Its electric energy production is 3.34 billio...Wujiangdu Hydropower Station of Guizhou is one of the biggest hydroelectric projects built in karst areas of China. It has a dam 165 m high, with a capacity of 630,000 kW. Its electric energy production is 3.34 billion kW-·h/a. Since its launching in 1979, the station has contributed a lot to the economy in Southwest China.展开更多
The exploitation of metallic mines may cause serious environmental problems.The removal of the heavy metals from the contaminated mining environments has become an urgent issue.In this paper,the occurrence and distrib...The exploitation of metallic mines may cause serious environmental problems.The removal of the heavy metals from the contaminated mining environments has become an urgent issue.In this paper,the occurrence and distribution of heavy metals in the calcareous tufa collected from the mining laneway of the Qixiashan Pb-Zn Mine in Nanjing were investigated by using multiple mineralogical techniques.Examination by X-ray diffraction spectrum(XRD) shows that calcite is the major compo-nent of the calcareous tufa.Several heavy metals such as Mn,Zn,Mg,Fe and Pb are detected in calcite by means of electron microprobe analysis.Although the heavy metal contents in the hostrock and the formation water are significantly low,the contents of Mn,Zn,Mg,Fe and Pb in the tufa calcite are as high as 23.65 wt%,9.6 wt%,0.76 wt%,4.44 wt% and 0.66 wt%,respectively.The back-scattered electron image shows complex compositional zoning texture in the tufa,which is linked directly to varia-tions in heavy metals,particularly in Mn and Zn.In addition,we also observed floccule and helical precipitations,which may be derived from the metabolism of the microbe.It is deduced that the occurrence and high concentration of heavy metals in tufa may be controlled by the activities of microbes.The results presented in this work suggest that calcite will be an important candidate for the remediation of the heavy metal contamination in mining areas.展开更多
基金Supported by the National Natural Science Fund ( 40872197, 40402004,40872168)~~
文摘Algae play a crucial role in the evolution of earth and life on earth,and also the cycle of matter.With its unique physiological and ecological properties and strong reproductive capacity,algae deeply influence the formation and development of karst.During the formation of tufa landscapes in Huanglong Scenic Area,the coloration,precipitation and corrosion of algae acting on tufa always concordantly exist.The algae living in water add gay colors to the tufa landscapes.The carbonate precipitation facilitated by algae is an important biological cause of the formation of tufa.As the external environmental conditions change,for instance,the shortage of karst water in tufa landscapes,the coloration and powerful corrosion of algae will stand out,which will badly affect the development and visual value of tufa landscapes.By studying the functions of algae in the tufa landscapes of Huanglong Scenic Area,this research was to provide scientific basis for the future study and protection of tufa landscapes.
基金Supported by the National Natural Science Foundation of China (Nos. 30970302, 40806063, 30830015, B49082401)
文摘Using shotgun sequencing data, the complete sequences of chloroplast 16S rRNA and tufA genes were acquired from native specimens of Bryopsis hypnoides (Qingdao, China). There are two group I introns in the 16S rRNA gene, which is structurally similar to that of Caulerpa sertularioides (Bryopsidales, Chlorophyta). The chloroplast-encoded tufA gene sequence is 1 230 bp long, very AT-rich (61.5%), and is similar to previously published 16S rRNA sequences of bryopsidinean algae. Phylogenetic analyses based on chloroplast 16S rRNA and tufA gene sequence data support previous hypotheses that the Bryopsidineae, Halimedineae, and Ostreobidineae are three distinct lineages. These results also confirmed the exclusion of Avrainvillea from the family Udoteaceae. Phylogenetic analyses inferred that the genus Bryopsis as sister to Derbesia; however, this clade lacked robust nodal support. Moreover, the phylogenetic tree inferred from rbcL GenBank sequences, combined with the geographical distributions of Bryopsis species, identified a strongly supportive clade for three differently distributed Asian Bryopsis species. The preliminary results suggesting that these organisms are of distinct regional endemism.
文摘The paper presents an analysis of characteristic karst tufa from Guangxi, China, which has not been studied before. A comparison with tufa from Dinaric Karst of Croatia is discussed in view of the C-type climate. The major mineral is calcite. Minor minerals are quartz and dolomite, depending on location. The content of calcium carbonate varies from 65% to 92%, and that of magnesium carbonate from 0.03% to 1.77%. Among other elements, the most abundant are Fe, from 0.02% to 1.50%, and Ti, from 0.15% to 0.27%. Many other trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, Hg and Pb) are also present. Specific activity of radionuclides 40K, 232Th, 137Cs, 226Ra and 238U varies from sample to sample. Concentration of U in tufa is close to that reported for sedimentary carbonate. Low concentration of 137Cs indicates that this part of the world was not exposed to nuclear explosions. The concentration of 226Ra is the highest in Mashan County. The ratio 238U/226Ra (0.21-0.71) in tufa from Mashan County is significantly lower than the theoretical value of 1. In 5 of the 11 studied samples, stable isotopes δ13C and δ18O were analyzed. They were dated by means of the 14C method. One tufa sample originated in the Pleistocene and the others in the Holocene. Because all of the tufa samples contain traces of Na and K, and K < Na, the tufa from Guangxi belong to the CO2-outgassing 'N' type according to the classification of Liu and He (1994).
基金Project supported by the National Natural Science Foundation of China.
文摘Wujiangdu Hydropower Station of Guizhou is one of the biggest hydroelectric projects built in karst areas of China. It has a dam 165 m high, with a capacity of 630,000 kW. Its electric energy production is 3.34 billion kW-·h/a. Since its launching in 1979, the station has contributed a lot to the economy in Southwest China.
基金Supported by National Basic Research Program of China (Grant No.2007CB815603)National Natural Science Foundation of China (Grant No.40573001)the Ph.D. Programs Foundation of Ministry of Education of China (Grant No.20050284044)
文摘The exploitation of metallic mines may cause serious environmental problems.The removal of the heavy metals from the contaminated mining environments has become an urgent issue.In this paper,the occurrence and distribution of heavy metals in the calcareous tufa collected from the mining laneway of the Qixiashan Pb-Zn Mine in Nanjing were investigated by using multiple mineralogical techniques.Examination by X-ray diffraction spectrum(XRD) shows that calcite is the major compo-nent of the calcareous tufa.Several heavy metals such as Mn,Zn,Mg,Fe and Pb are detected in calcite by means of electron microprobe analysis.Although the heavy metal contents in the hostrock and the formation water are significantly low,the contents of Mn,Zn,Mg,Fe and Pb in the tufa calcite are as high as 23.65 wt%,9.6 wt%,0.76 wt%,4.44 wt% and 0.66 wt%,respectively.The back-scattered electron image shows complex compositional zoning texture in the tufa,which is linked directly to varia-tions in heavy metals,particularly in Mn and Zn.In addition,we also observed floccule and helical precipitations,which may be derived from the metabolism of the microbe.It is deduced that the occurrence and high concentration of heavy metals in tufa may be controlled by the activities of microbes.The results presented in this work suggest that calcite will be an important candidate for the remediation of the heavy metal contamination in mining areas.
