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981.
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983.
Holocene monsoon climate documented by oxygen and carbon isotopes from lake sediments and peat bogs in China: a review and synthesis 总被引:1,自引:0,他引:1
Jiawu Zhang Fahu Chen Jonathan A. Holmes Hui Li Xiaoyan Guo Junlan Wang Shuang Li Yanbin Lü Yan Zhao Mingrui Qiang 《Quaternary Science Reviews》2011,30(15-16):1973-1987
There has been much recent debate about Holocene climate variation in the monsoon region of China, especially the temporal pattern of variations in precipitation, the time-transgressive nature of the Holocene precipitation maximum, and the extent to which variations in regions influenced by the Indian Summer Monsoon (ISM) and the East Asian Summer Monsoon (EASM) have been synchronous. We summarize and compare carbonate oxygen-isotope records (δ18Ocarb) from ten lakes within the present-day ISM region. We discuss their paleoclimate significance considering the present-day moisture source, isotopic composition of precipitation and the hydrological setting. The δ18Ocarb records are controlled mainly by the isotopic composition of lake water, which in turn is a function of regional Precipitation/Evaporation (P/E) balance and the proportion of precipitation that is monsoon-derived. We normalized the δ18Ocarb data and used these records to generate an integrated moisture index. This index, along with oxygen-isotope records from speleothems and carbon-isotope records (δ13Corg) from peats within the monsoon region, suggests that Holocene climate was broadly synchronous across the monsoon region and, within the limits of accuracy of the existing age models, provides no strong evidence for previously-proposed anti-phasing of the ISM and the EASM. Stable-isotope records from lake sediments and peat bogs have excellent potential for providing high-quality paleoclimate data for monsoon Asia, and complement high-resolution speleothem sequences, which are only found in certain localities. 相似文献
984.
Stratigraphy of the Triassic?Jurassic Boundary Successions of the Southern Margin of the Junggar Basin, Northwestern China 总被引:2,自引:1,他引:1
SHA Jingeng Vivi VAJDA PAN Yanhong Linda LARSSON YAO Xiaogang ZHANG Xiaolin WANG Yaqiong CHENG Xiansheng JIANG Baoyu DENG Shenghui CHEN Siwei PENG Bo 《《地质学报》英文版》2011,85(2):421-436
The Triassic?Jurassic (Tr?J) boundary marks a major extinction event, which (~200 Ma) resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr?J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected: the Late Triassic (Rhaetian) Aratrisporites?Alisporites Assemblage, the Early Jurassic (Hettangian) Perinopollenites?Pinuspollenites Assemblage, and the Sinemurian Perinopollenites?Cycadopites Assemblage. The Tr?J boundary is placed between bed 44 and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha (?), Unio?Ferganoconcha and Waagenoperna?Yananoconcha bivalve assemblages are recognized. The Ferganoconcha (?) bed is limited to the upper Haojiagou Formation, Unio?Ferganoconcha and Waagenoperna?Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine?littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian. 相似文献
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988.
针铁矿和菱苦土强化养殖粪污厌氧发酵液中氮、磷固定的研究 总被引:1,自引:0,他引:1
对比研究了养殖粪污厌氧发酵体系中添加针铁矿和/或菱苦土对N、P固定的作用。实验过程中对溶液pH进行监控,厌氧发酵44 d后,对发酵液中氨氮和磷浓度进行了分析,对固体产物进行了XRD和SEM分析。结果表明:单独或同时添加针铁矿、菱苦土的厌氧发酵罐中,发酵液中N、P浓度均降低,其中N浓度降幅小于P,添加菱苦土厌氧发酵罐中P浓度降幅较大,达90%以上。单独添加针铁矿的厌氧发酵罐中,针铁矿发生还原分解,转化为铁白云石;添加菱苦土的厌氧发酵罐中,形成了大量鸟粪石。研究认为在养殖粪污厌氧发酵体系中,由于碱金属离子的影响,针铁矿和菱苦土对N的固定作用不明显;针铁矿对P的固定效果一般,菱苦土对P固定效果显著,固P产物鸟粪石可作为优质缓释肥使用。 相似文献
989.
白云岩酸解法制备轻质氧化镁和碳酸钙实验研究 总被引:1,自引:0,他引:1
以河南卢氏县黄跃沟纯质白云岩为原料,利用盐酸进行分解,制得MgCl2-CaCl2溶液。经过通氨气调节pH值除铁、氨化反应、陈化反应以及碳化反应等过程,制备轻质氧化镁和轻质碳酸钙,研究氨化过程中温度和时间对Mg2+沉淀率的影响,以及碳化时间对碳酸钙制品晶型的影响。采用化学分析方法和扫描电镜分析对制品进行表征,结果表明:轻质氧化镁制品颗粒形貌呈片状,粒径为150 nm左右,其性能达到HG/T2573—2006优等品标准;轻质碳酸钙制品颗粒形貌呈球状,粒径为100 nm左右,其性能达到HG/T2567—1994优等品的标准。实验采用的工艺路线具有能耗低、白云石资源利用率高、加工过程符合清洁生产要求等优点,是白云岩资源高效利用的有效途径之一。 相似文献
990.