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Guanghui Dong Zhengkai Xia Robert Elston Xiongwei Sun Fahu Chen 《Frontiers of Earth Science》2009,3(3):279-285
In this paper, we examined the response of geochemical records in lacustrine sediments to climate and human activity in Mengjin,
Henan Province of China during the middle Holocene. Indices used in this study include K, Na, Mn, Ba, Sr, Al, Ti, cation ratios,
and Gramineae pollen in lacustrine sediments. Results indicate a drought event in this area around 5660 cal a BP, which weakened
soil leaching and changed the element composition of surface soil runoff entering the paelo-lake and lacustrine sediments.
Human activity appearing from 4695 cal a BP to 4000 cal a BP also affected the chemical composition of lake sediments. Human
activities led to enhanced soil erosion and destroyed soil leaching horizons. Therefore, the substance of soil illuvial layer
exposed to the surface and entering the paleo-lake were substantially altered by human activities. 相似文献
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随着矿井开采深度的加大,矿井的透气性越来越小,煤与瓦斯突出事故频发,揭煤难度也越来越大。孟津煤矿开采山西组二。煤层,属于构造煤,煤层松软,透气性低,矿井一水平开采深度为760m,瓦斯压力高。副井清理斜巷需穿过二,煤层,为了尽快揭开煤层,采用液压钻机配乳化液泵以提高钻探水压的冲煤措施,使高应力低透气松软煤层在揭煤时的不利因素转化为可利用因素。从施工的55个揭煤孔来看,单孔冲出煤量最大为2.3t,最小为0.4t,平均为1.06t,总计冲出煤量为58.5t。通过对控制区域6个点瓦斯含量的测定,结果表明,瓦斯含量降到了8m3/t以下.清除了突出危险。采用瓦斯解析指标进行了三次效果检验,Ah:最大值为190MPa;在岩柱1.5m布置爆破孔,采用震动爆破揭开煤层,瞬时最大瓦斯涌出量为2.4m3/min,说明达到了快速揭煤的目的。 相似文献
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