The isotopic composition of soil or paleosol carbonate can be a sensitive paleoclimatic indicator. The relationships between the oxygen isotopic composition of modem soil carbonates and that of meteoric waters and bet...The isotopic composition of soil or paleosol carbonate can be a sensitive paleoclimatic indicator. The relationships between the oxygen isotopic composition of modem soil carbonates and that of meteoric waters and between the carbon isotopic composition of the soil carbonates and the fraction of the plants using the C<sub>4</sub> photosynthetic pathway in展开更多
The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core （BSTC2000） taken from Bosten Lake. Multiple pro...The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core （BSTC2000） taken from Bosten Lake. Multiple proxies of this core, including the mineral components of carbonate, carbonate content, stable isotopic compositions of carbonate, Ca/Sr, TOC and C/N and C/S of organic matter, are used to reconstruct the climatic change since 8500 a B.P. The chronology model is made by nine AMS 14C ages of leaves, seeds and organic matter contained in two parallel cores. The climate was cold and wet during 8500 to 8100 a B.P. Temperature increased from 8100 to 6400 a B.P., the climate was warm and humid, and the lake expanded. The lake level was highest during this stage. Then from 6400 to 5100 a B.P., the climate became cold and the lake level decreased slightly. During the late mid-Holocene, the climate was hot and dry from 5100 to 3100 a B.P., but there was a short cold period during 4400 to 3800 a B.P. At this temporal interval, a mass of ice and snow melting water supplied the lake at the early time and made the lake level rise. The second highest lake level stage occurred during 5200 to 3800 a B.P. The climate was cool and wet during 3100 to 2200 a B.P., when the lake expanded with decreasing evaporation. The lake had the last short-term high level during 3100 to 2800 a B.P. After this short high lake level period, the lake shrank because of the long-term lower temperature and reduced water supply. From 2200 to 1200 a B.P., the climate was hot and dry, and the lake shrank greatly. Although the temperature decreased somewhat from 1200 a B.P. to the present, the climate was warm and dry. The lake level began to rise a little again, but it did not reach the river bed altitude of the Konqi River, an outflow river of the Bosten Lake.展开更多
鱼台凹陷是一个中生代同沉积断陷盆地,其内部构造纵横,深部普遍发育奥陶系碳酸盐岩,具备地热开发前景。为研究断陷盆地内碳酸盐岩热储特征,评价其资源潜力,在鱼台凹陷施工一眼2309.31 m深钻孔,通过综合测井、产能测试、水化学分析、气...鱼台凹陷是一个中生代同沉积断陷盆地,其内部构造纵横,深部普遍发育奥陶系碳酸盐岩,具备地热开发前景。为研究断陷盆地内碳酸盐岩热储特征,评价其资源潜力,在鱼台凹陷施工一眼2309.31 m深钻孔,通过综合测井、产能测试、水化学分析、气体成分分析、地热水^(14)C年龄测定等手段,分析了盆地内地热流体的来源及补给、热源储集、离子运移等条件。结果显示,地热井温曲线的增温异常与裂隙发育断位置一致,指示了地热水来源方向;地热水Cl^(-)、Na^(+)含量较高,其离子组分形成原因与岩盐溶解有关;鱼台凹陷东南部断裂交会处附近地热水表观年龄43.5 ka BP,校正年龄10.752 ka BP,时间在第四纪更新世晚期至全新世早期。研究认为,鱼台凹陷存在较为活跃或年轻的地质构造,是热储的热源之一,区内奥陶系热储可采地热资源量约为2.12×10^(9)GJ,合标准煤7.27×10^(7)t,资源潜力较大,开发利用前景良好。展开更多
Thorium-234 and particle composition （organic matter, biogenic silica, carbonate and lithogenic component） were examined in the East China Sea （ECS） and the northern South China Sea （NSCS） in order to constrain ...Thorium-234 and particle composition （organic matter, biogenic silica, carbonate and lithogenic component） were examined in the East China Sea （ECS） and the northern South China Sea （NSCS） in order to constrain the particle types scavenging thorium isotopes. Good positive correlations between particulate organic matter （POM） or carbonate and thorium-234 in suspended particulate matter （SPM） indicates that POM and carbonate are efficient to scavenge thorium-234. No relationship between biogenic silica and thorium-234 suggests that geochemical behavior of thorium-234 may be not influenced by biogenic silica. A simple model was used to evaluate the affinity of thorium-234 to different particle components. The results show that POM is the most efficient scavenger for thorium-234 in the ECS and the NSCS, followed by carbonate. The authors＇ results lend support to the utility of thorium-234 as a proxy of POC and carbonate in the upper layer. However, the strong dependence of thorium scavenging on particle composition challenges thorium-230 as a constant flux proxy.展开更多
Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content.The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upf...Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content.The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket(UASB)reactors.Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate as substrate,respectively.There was an obvious accumulation of inorganic precipitate observed in the biogranules.Observations via scanning electron microscope(SEM)and energy dispersive spectroscopy(EDS)showed that the acclimated biogranules in the two reactors differed in microstructure.Calcium carbonate was found to have precipitated on the surface of acetate-degrading biogranules,but precipitated at the core of the carbohydrate-degrading biogranules.The results indicated that substrates had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge,which was expected due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates.Moreover,the location of calcium carbonate precipitation substantially affected the specific methanogenic activity(SMA)of the granular sludge.The SMA of the acetate-degrading biogranules dropped from 1.96 gCODCH4·gVSS^(–1)·d^(–1)to 0.61 gCODCH4·gVSS^(–1)·d^(–1)after 180-d of operation in the reactor.However,the SMA of the carbohydrate-degrading biogranules was not adversely affected by calcium carbonate precipitation.展开更多
The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic frac...The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic fractionation between cellulose and its source water,the oxygen isotopic composition of paleo-lake water has been established quantitatively.Combined oxygen isotopic values of cellulose and carbonates were used in the‘Craig’equation to determine paleotemperatures and their variation in the lake during the past 500 years.Results show that the paleotemperature trend correlates well with meteorological records from Weining.There are four notable cold intervals at Lake Caohai over the past 500 years,namely 1540–1570AD,1670–1715AD,1780–1870AD and 1900–1930AD,and the former three cold intervals have been observed in the conventional Little Ice Age(LIA).These cold periods at Lake Caohai correspond well with those recorded from tree ring,peat,and ice core data from adjacent regions,particularly temperature those inferred fromδ18O of peat cellulose from Hongyuan Southwestern China.The trend in paleotemperature variations at Lake Caohai are also consistent with both the change of Indian summer monsoon,derived fromδ18O values of a stalagmite in Dongge,and a recorded shift in solar activity.The findings of this study illustrate that coupled analysis ofδ18O values of cellulose and carbonates from lake sediments may be used as a paleotemperature proxy.These results also provide further evidence of the existence of LIA in southwestern China.展开更多
基金Project supported by Xi'an Laboratory of Loess and Quaternary Geology, Academia Sinica
文摘The isotopic composition of soil or paleosol carbonate can be a sensitive paleoclimatic indicator. The relationships between the oxygen isotopic composition of modem soil carbonates and that of meteoric waters and between the carbon isotopic composition of the soil carbonates and the fraction of the plants using the C<sub>4</sub> photosynthetic pathway in
基金co-supported by the National Natural Science Foundation of China (grant Nos.40773064,40331012 and 40041004)"973" Program of China (No.G1999043501)
文摘The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core （BSTC2000） taken from Bosten Lake. Multiple proxies of this core, including the mineral components of carbonate, carbonate content, stable isotopic compositions of carbonate, Ca/Sr, TOC and C/N and C/S of organic matter, are used to reconstruct the climatic change since 8500 a B.P. The chronology model is made by nine AMS 14C ages of leaves, seeds and organic matter contained in two parallel cores. The climate was cold and wet during 8500 to 8100 a B.P. Temperature increased from 8100 to 6400 a B.P., the climate was warm and humid, and the lake expanded. The lake level was highest during this stage. Then from 6400 to 5100 a B.P., the climate became cold and the lake level decreased slightly. During the late mid-Holocene, the climate was hot and dry from 5100 to 3100 a B.P., but there was a short cold period during 4400 to 3800 a B.P. At this temporal interval, a mass of ice and snow melting water supplied the lake at the early time and made the lake level rise. The second highest lake level stage occurred during 5200 to 3800 a B.P. The climate was cool and wet during 3100 to 2200 a B.P., when the lake expanded with decreasing evaporation. The lake had the last short-term high level during 3100 to 2800 a B.P. After this short high lake level period, the lake shrank because of the long-term lower temperature and reduced water supply. From 2200 to 1200 a B.P., the climate was hot and dry, and the lake shrank greatly. Although the temperature decreased somewhat from 1200 a B.P. to the present, the climate was warm and dry. The lake level began to rise a little again, but it did not reach the river bed altitude of the Konqi River, an outflow river of the Bosten Lake.
文摘鱼台凹陷是一个中生代同沉积断陷盆地,其内部构造纵横,深部普遍发育奥陶系碳酸盐岩,具备地热开发前景。为研究断陷盆地内碳酸盐岩热储特征,评价其资源潜力,在鱼台凹陷施工一眼2309.31 m深钻孔,通过综合测井、产能测试、水化学分析、气体成分分析、地热水^(14)C年龄测定等手段,分析了盆地内地热流体的来源及补给、热源储集、离子运移等条件。结果显示,地热井温曲线的增温异常与裂隙发育断位置一致,指示了地热水来源方向;地热水Cl^(-)、Na^(+)含量较高,其离子组分形成原因与岩盐溶解有关;鱼台凹陷东南部断裂交会处附近地热水表观年龄43.5 ka BP,校正年龄10.752 ka BP,时间在第四纪更新世晚期至全新世早期。研究认为,鱼台凹陷存在较为活跃或年轻的地质构造,是热储的热源之一,区内奥陶系热储可采地热资源量约为2.12×10^(9)GJ,合标准煤7.27×10^(7)t,资源潜力较大,开发利用前景良好。
基金The National Natural Science Foundation of China under contract Nos 40606022 and 90411016 the National Key Basic Research Special Foundation Program of China under contract No 2005CB422305
文摘Thorium-234 and particle composition （organic matter, biogenic silica, carbonate and lithogenic component） were examined in the East China Sea （ECS） and the northern South China Sea （NSCS） in order to constrain the particle types scavenging thorium isotopes. Good positive correlations between particulate organic matter （POM） or carbonate and thorium-234 in suspended particulate matter （SPM） indicates that POM and carbonate are efficient to scavenge thorium-234. No relationship between biogenic silica and thorium-234 suggests that geochemical behavior of thorium-234 may be not influenced by biogenic silica. A simple model was used to evaluate the affinity of thorium-234 to different particle components. The results show that POM is the most efficient scavenger for thorium-234 in the ECS and the NSCS, followed by carbonate. The authors＇ results lend support to the utility of thorium-234 as a proxy of POC and carbonate in the upper layer. However, the strong dependence of thorium scavenging on particle composition challenges thorium-230 as a constant flux proxy.
基金the National Science and Technology Major Special“Water Pollution Control and Governance”of China(No.2009ZX07212-002-002)the National Natural Science Foundation of China(Grant No.20946001)+1 种基金the Science and Technology Development Program of Shanxi Province in China(No.2006kz08-G2)the Fundamental Research Funds for the Central Universities.
文摘Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content.The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket(UASB)reactors.Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate as substrate,respectively.There was an obvious accumulation of inorganic precipitate observed in the biogranules.Observations via scanning electron microscope(SEM)and energy dispersive spectroscopy(EDS)showed that the acclimated biogranules in the two reactors differed in microstructure.Calcium carbonate was found to have precipitated on the surface of acetate-degrading biogranules,but precipitated at the core of the carbohydrate-degrading biogranules.The results indicated that substrates had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge,which was expected due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates.Moreover,the location of calcium carbonate precipitation substantially affected the specific methanogenic activity(SMA)of the granular sludge.The SMA of the acetate-degrading biogranules dropped from 1.96 gCODCH4·gVSS^(–1)·d^(–1)to 0.61 gCODCH4·gVSS^(–1)·d^(–1)after 180-d of operation in the reactor.However,the SMA of the carbohydrate-degrading biogranules was not adversely affected by calcium carbonate precipitation.
基金supported by the National Natural Science Foundation of China(Grant No.40673068)the National Science and Technology Support Program of China(Grant No.2011BAC02B0201)the Natural Science Foundation of Guizhou Province,China
文摘The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic fractionation between cellulose and its source water,the oxygen isotopic composition of paleo-lake water has been established quantitatively.Combined oxygen isotopic values of cellulose and carbonates were used in the‘Craig’equation to determine paleotemperatures and their variation in the lake during the past 500 years.Results show that the paleotemperature trend correlates well with meteorological records from Weining.There are four notable cold intervals at Lake Caohai over the past 500 years,namely 1540–1570AD,1670–1715AD,1780–1870AD and 1900–1930AD,and the former three cold intervals have been observed in the conventional Little Ice Age(LIA).These cold periods at Lake Caohai correspond well with those recorded from tree ring,peat,and ice core data from adjacent regions,particularly temperature those inferred fromδ18O of peat cellulose from Hongyuan Southwestern China.The trend in paleotemperature variations at Lake Caohai are also consistent with both the change of Indian summer monsoon,derived fromδ18O values of a stalagmite in Dongge,and a recorded shift in solar activity.The findings of this study illustrate that coupled analysis ofδ18O values of cellulose and carbonates from lake sediments may be used as a paleotemperature proxy.These results also provide further evidence of the existence of LIA in southwestern China.
