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991.
With the rapid economic development, the water quality is worsening and red tide takes place frequently in the Changjiang Estuary and adjacent seawaters. To improve the marine water quality, the total inland pollutant load should be controlled effectively. With efficiency and fairness in consideration, the total maximum allowable loads of CODMn, NH3–N, inorganic nitrogen and active phosphate to the seawaters were calculated and allocated by the linear programming method based on the water quality response fields of the pollution sources. The maximum allowable loads are 2008 × 103 tons, 169 × 103 tons, 226 × 103 tons and 18 × 103 tons for CODMn, NH3–N, inorganic nitrogen and active phosphate when the water quality targets are requested to be achieved in the whole studied region, and 346 × 103 tons and 32 × 103 tons for inorganic nitrogen and active phosphate when the water quality targets to be achieved only in the red tide sensitive area. The cut task of CODMn and NH3–N is relatively easy and can be finished by the watershed environmental plan; while the cut task of inorganic nitrogen and active phosphate is tremendous. The coastal provinces should install more denitrification and dephosphorization facilities in the existing waste water treatment plants or build new ones to control the red tides in the concerned seawaters. 相似文献
992.
Based on China's observational data in 1951-1990,after minimizing the possible biasescaused by station relocation and urban heat island,the spatial and temporal distributions of trendsfor maximum and minimum temperatures are studied.The results show that increasing trends ofmaximum temperatures are in the areas west to 95°E,and north to the Huanghe(Yellow)River,while decreasing trends exist in eastern China south to the Yellow River.Minimum temperaturesare generally increasing throughout China,with dominant warming trends at the higher latitudes.This resulted in very obvious decreasing trends in diurnal temperature ranges.The periodic cycles are consistent between the maximum and minimum temperatures,butasymmetric trends are very obvious.The significant increase of minimum(nighttime)temperaturesreflects the evidence of enhancement of greenhouse effect.Further analysis shows that the changesof maximum and minimum temperatures are mainly related to sunshine duration and atmosphericwater vapor content. 相似文献
993.
994.
西藏罗布莎蛇绿岩铬铁矿中金刚石的研究 总被引:27,自引:3,他引:27
在西藏罗布莎豆荚状铬铁矿中发现过金刚石,但迄今仍有人因为自己所取的小试样中没有分离出金刚石而否定罗布莎等地金刚石的存在。由于金刚石涉及西藏雅鲁藏布江缝合线和蛇绿岩、铬铁矿成因等问题,笔者重新在罗布莎铬铁矿中取样,经过选矿,又在1500kg样品中选出了25粒金刚石和近70种伴生矿物。这就表明西藏金刚石是的确存在的,而且它和蛇绿岩的铬铁矿同是深部成因的产物。 相似文献
995.
996.
第四纪松散沉积物中活断层滑动面的显微构造研究方法 总被引:3,自引:0,他引:3
第四纪松散深积物中的活断层滑动面是重要的古地震遗迹,也是鉴定古地震事件和确定古地震时代的重要标志。以往,以第四纪松散沉积物中活断层滑动面主要借助宏观观察进行研究,但遇到了一些难以解决的问题,如隐性断层问题。作者利用显微构造分析,找到了研究这些问题的途径,其方法是对第四纪松散沉积物进行定向原状样品采集,通过室内样品固结,显微薄片制作和显微构造现象观察等,从显微域里研究各种变形现象。用此方法,可以在没有宏观资料支持的情况下确定断面的运动性质;发现并描述第四纪松散沉积物中的隐性断层,研究断层的尖来机制,还可以对工程建设场地发现的不同松散沉积物相接触的现象进行活断层鉴别。 相似文献
997.
Luo Zhaohua Xiao Xuchang Cao Yongqing Mo Xuanxue Su Shangguo Deng Jinfu Zhang Wenhui 《中国科学D辑(英文版)》2001,44(1):10-17
Geodynamic properties and evolution of the lithosphere on the north margin of the Tibetan Plateau are recently hot topics to geoscientists in the world. Have the northern plates been subducting underneath the Plateau? It is still an unsolved problem. One of the keys to solving this problem is to understand the genetic processes of Cenozoic magmas on the north margin of the Tibetan Plateau. However, there is no enough evidence supporting the subduction model. In contrast, a series of evidence indicates that collision-induced huge shearing faults and large-scale crust shortening played a main role in lithosphere motion on the north margin of the Tibetan Plateau. The mantle-derived igneous rocks strictly distribute at the intersections of large strike-slip faults on the north margin of the Plateau. Generation of magmas may be related to local extensional condition induced by strike-slipping faults, which lead to lithosphere gravitational instability and collapse, as well as upwelling of the deep hot material. Heat induced by shearing and carried by upwelling hot material may cause partial melting on H2O-bearing mantle. 相似文献
998.
Li Yalin Wang Chengshan Yi Haisheng Deng Bin Liu Chiyang Yang Xingke Lai Shaocong Fang Weixuan 《中国科学D辑(英文版)》2001,44(1):284
The latest Qiangtang Terrane structure is characterized by the south-north-trending graben formed during the eastwestward extensional processes. The Shuanghu graben is composed of a series of nearly parallel NE to NNE-trending normal faults. Studies on fault geometry, kinematics and sedimentation in the fault-controlled basin suggest that the faults activated periodically and their early activities began in the Pliocene, which caused the unconformable contact between the Pliocene and the subjacent Shuanghu Formation, as well as between the Pliocene and the overlying Quaternary. The movement rates of the faults had been strikingly increased since Quaternary when the faults activated intensively. The graben resulted from the gravitational spreading after the uplift of the Tibetan Plateau. It is indicated that the collapse has been on setting in plateau hinterland. 相似文献
999.
According to classification system of wetland in Ramsar Convention, salt marsh belongs to inland salt lake formed by regional hydrogeologic and climatic conditions[1]. In western Songnen Plain, the most distinct characteristic of water environment in salt marsh wetlands is that many water bodies have high salt contents and pH values, so salt marsh wetlands are categorized as a special natural synthesis[2]. 1 Natural environment in western Songnen PlainThe Songnen Plain lies to the east of … 相似文献
1000.