Effects of pen fish culture in Taihu lake were studied and summarized. During 1984 to 2001, pen fish culture of Taihu lake developed from extensive models to intensive and high-returned ones, the cultured species were...Effects of pen fish culture in Taihu lake were studied and summarized. During 1984 to 2001, pen fish culture of Taihu lake developed from extensive models to intensive and high-returned ones, the cultured species were shifted from fishes to crabs. Pen fish culture has caused eutrophication and detrimental effect to the ecological environment and fishery. The measures of sustainable development for pen fish culture and ecological environment protection were suggested.展开更多
The type, grain size and origin of ferrimagnetic minerals separated from red paleosols of Pleistocene Epoch (Q\-2) in eastern China, were studied by using mineral magnetic measurement, X\|ray powder diffraction and el...The type, grain size and origin of ferrimagnetic minerals separated from red paleosols of Pleistocene Epoch (Q\-2) in eastern China, were studied by using mineral magnetic measurement, X\|ray powder diffraction and electron microscopy. Results showed that the iron oxides in red paleosols were composed of hematite (α\|Fe\-2O\-3), maghemite (γ\|Fe\-2O\-3) and goethite(α\|FeOOH). Mineral magnetic parameters and X\|ray diffraction patterns indicated that maghemite was the dominant remanence carrier in red paleosols, which is characterized by superparamagnetic (SP) and stable single domain (SSD) grains. The variations of magnetic susceptibility (χ), anhysteretic magnetic susceptibility (χ\-\{ARM\}) and saturation isothermal remanent magnetization (SIRM) for red paleosols following heating to various temperatures showed two peak values at 700℃ and 900℃. The spherulitic magnetic particles measuring \{250-1000\}μm in diameter in red paleosols were separated by the magnetic separation method, indicating that these magnetic particles were an assemblage of superparamagnetic and stable single domain ferrimagnetic grains. It is suggested that the ferrimagnetic minerals of red paleosols be a pedogenic ferrimagnetic component under high temperature and high humid conditions in the Pleistocene Epoch (Q\-2). It is concluded that the magnetism characteristics of red paleosols can be used to evaluate the environmental changes of Quaternary in eastern China.展开更多
通过对获取的巢湖湖泊沉积岩芯的磁化率与粒度组合特征的分析，结合孢粉及相邻其它区域的环境考古资料，得出该岩芯柱样所反映的环境变化信息。结果表明：（1）巢湖湖泊沉积物磁化率曲线在117cm以下总体上比较平稳而略有下降，117cm以...通过对获取的巢湖湖泊沉积岩芯的磁化率与粒度组合特征的分析，结合孢粉及相邻其它区域的环境考古资料，得出该岩芯柱样所反映的环境变化信息。结果表明：（1）巢湖湖泊沉积物磁化率曲线在117cm以下总体上比较平稳而略有下降，117cm以上人类活动所导致的侵蚀作用加剧使得磁化率值异常升高；（2）本岩芯柱样117cm以下样品的磁化率强度与粘土的百分比含量呈正相关，而与粉砂组分的百分比含量成负相关；（3）根据磁化率与粒度组合变化特征，结合孢粉分析及全新世以来区域气候变化背景，9870 Cal a B．P．以来的巢湖流域古气候环境演变可以划分6个不同的时期：9870～7000 Cal a B．P．，气候呈温和略干的特点；7000～4750 Cal a B．P．，气候温暖湿润；4750～2170 Cal a B．P．，流域气候温和干燥，巢湖湖盆局部地区可能出露水面以上；2170～1040 Cal a B．P．，气候总体上温和湿润，但是冷暖波动明显；1040～200 Cal a B．P．流域处在温凉稍湿的时期，人类活动逐渐加强；200 Cal a B．P．至今，流域总体上处于相对温暖湿润阶段。展开更多
Mineral magnetic measurements have been made on Quaternary Red Earth profilesfrom Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons havebeen identified on the basis of magnetic suscep...Mineral magnetic measurements have been made on Quaternary Red Earth profilesfrom Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons havebeen identified on the basis of magnetic susceptibility, anhysteretic remanent magnetization,saturation isothermal remanent magnetization and magnetization parameters measurements.Magnetic measurements revealed that there were great variations in ferrimagnetic mineralconcentration, mineralogy assemblages and grain size in Quaternary Red Earth profiles, suggestingthat these variations reflect pedogenic processes fluctuation and environmental changes. Thepreliminary results indicate that mineral magnetic measurement of Quaternary Red Earth is usefulfor studying the Quaternary environmental changes recorded in paleosols.展开更多
基金This study was supported by the National Natural Science Foundation of China(3028018).
文摘Effects of pen fish culture in Taihu lake were studied and summarized. During 1984 to 2001, pen fish culture of Taihu lake developed from extensive models to intensive and high-returned ones, the cultured species were shifted from fishes to crabs. Pen fish culture has caused eutrophication and detrimental effect to the ecological environment and fishery. The measures of sustainable development for pen fish culture and ecological environment protection were suggested.
文摘The type, grain size and origin of ferrimagnetic minerals separated from red paleosols of Pleistocene Epoch (Q\-2) in eastern China, were studied by using mineral magnetic measurement, X\|ray powder diffraction and electron microscopy. Results showed that the iron oxides in red paleosols were composed of hematite (α\|Fe\-2O\-3), maghemite (γ\|Fe\-2O\-3) and goethite(α\|FeOOH). Mineral magnetic parameters and X\|ray diffraction patterns indicated that maghemite was the dominant remanence carrier in red paleosols, which is characterized by superparamagnetic (SP) and stable single domain (SSD) grains. The variations of magnetic susceptibility (χ), anhysteretic magnetic susceptibility (χ\-\{ARM\}) and saturation isothermal remanent magnetization (SIRM) for red paleosols following heating to various temperatures showed two peak values at 700℃ and 900℃. The spherulitic magnetic particles measuring \{250-1000\}μm in diameter in red paleosols were separated by the magnetic separation method, indicating that these magnetic particles were an assemblage of superparamagnetic and stable single domain ferrimagnetic grains. It is suggested that the ferrimagnetic minerals of red paleosols be a pedogenic ferrimagnetic component under high temperature and high humid conditions in the Pleistocene Epoch (Q\-2). It is concluded that the magnetism characteristics of red paleosols can be used to evaluate the environmental changes of Quaternary in eastern China.
文摘通过对获取的巢湖湖泊沉积岩芯的磁化率与粒度组合特征的分析，结合孢粉及相邻其它区域的环境考古资料，得出该岩芯柱样所反映的环境变化信息。结果表明：（1）巢湖湖泊沉积物磁化率曲线在117cm以下总体上比较平稳而略有下降，117cm以上人类活动所导致的侵蚀作用加剧使得磁化率值异常升高；（2）本岩芯柱样117cm以下样品的磁化率强度与粘土的百分比含量呈正相关，而与粉砂组分的百分比含量成负相关；（3）根据磁化率与粒度组合变化特征，结合孢粉分析及全新世以来区域气候变化背景，9870 Cal a B．P．以来的巢湖流域古气候环境演变可以划分6个不同的时期：9870～7000 Cal a B．P．，气候呈温和略干的特点；7000～4750 Cal a B．P．，气候温暖湿润；4750～2170 Cal a B．P．，流域气候温和干燥，巢湖湖盆局部地区可能出露水面以上；2170～1040 Cal a B．P．，气候总体上温和湿润，但是冷暖波动明显；1040～200 Cal a B．P．流域处在温凉稍湿的时期，人类活动逐渐加强；200 Cal a B．P．至今，流域总体上处于相对温暖湿润阶段。
文摘Mineral magnetic measurements have been made on Quaternary Red Earth profilesfrom Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons havebeen identified on the basis of magnetic susceptibility, anhysteretic remanent magnetization,saturation isothermal remanent magnetization and magnetization parameters measurements.Magnetic measurements revealed that there were great variations in ferrimagnetic mineralconcentration, mineralogy assemblages and grain size in Quaternary Red Earth profiles, suggestingthat these variations reflect pedogenic processes fluctuation and environmental changes. Thepreliminary results indicate that mineral magnetic measurement of Quaternary Red Earth is usefulfor studying the Quaternary environmental changes recorded in paleosols.
