选用硫酸铝和聚合氯化铝(PAC)对化机浆高浓废液进行处理,考察两种铝盐降低废液化学需氧量的效果。结果表明:硫酸铝和聚合氯化铝均在加入量为1%时,对降低废液化学需氧量效果最佳,降幅分别约40%和50%;加入阳离子聚丙烯酰胺(C PA M)可以加...选用硫酸铝和聚合氯化铝(PAC)对化机浆高浓废液进行处理,考察两种铝盐降低废液化学需氧量的效果。结果表明:硫酸铝和聚合氯化铝均在加入量为1%时,对降低废液化学需氧量效果最佳,降幅分别约40%和50%;加入阳离子聚丙烯酰胺(C PA M)可以加快废液析出物的沉降。聚合氯化铝特别适用于降低化机浆高浓废液的溶解性COD,为后续环保分厂废液处理减轻了压力。展开更多
Historical documents provide evidence for regional droughts preceding the political turmoil and fall of Beijing in 1644 CE,when more than 20 million people died in northern China during the late Ming famine period.How...Historical documents provide evidence for regional droughts preceding the political turmoil and fall of Beijing in 1644 CE,when more than 20 million people died in northern China during the late Ming famine period.However,the role climate and environmental changes may have played in this pivotal event in Chinese history remains unclear.Here,we provide tree-ring evidence of persistent megadroughts from1576 to 1593 CE and from 1628 to 1644 CE in northern China,which coincided with exceptionally cold summers just before the fall of Beijing.Our analysis reveals that these regional hydroclimatic extremes are part of a series of megadroughts along the Pacific Rim,which not only impacted the ecology and society of monsoonal northern China,but likely also exacerbated external geopolitical and economic pressures.This finding is corroborated by last millennium reanalysis data and numerical climate model simulations revealing internally driven Pacific sea surface temperature variations and the predominance of decadal scale La Ni?a-like conditions to be responsible for precipitation decreases over northern China,as well as extensive monsoon regions in the Americas.These teleconnection patterns provide a mechanistic explanation for reoccurring drought spells during the late Ming Dynasty and the environmental framework fostering the fall of Beijing in 1644 CE,and the subsequent demise of the Ming Dynasty.展开更多
文摘选用硫酸铝和聚合氯化铝(PAC)对化机浆高浓废液进行处理,考察两种铝盐降低废液化学需氧量的效果。结果表明:硫酸铝和聚合氯化铝均在加入量为1%时,对降低废液化学需氧量效果最佳,降幅分别约40%和50%;加入阳离子聚丙烯酰胺(C PA M)可以加快废液析出物的沉降。聚合氯化铝特别适用于降低化机浆高浓废液的溶解性COD,为后续环保分厂废液处理减轻了压力。
基金supported by the Basic Science Center for Tibetan Plateau Earth System(BSCTPES,41988101)the National Natural Science Foundation of China(32061123008)+3 种基金Ulf Büntgen and Jan Esper were supported by the ERC Advanced Grant Monostar(Ad G 882727)the Czech Science Foundation(23-08049S,HYDRO8)Fredrik Charpentier Ljungqvist was supported by the Swedish Research Council(Vetenskapsr?det,2018-01272)the Marianne and Marcus Wallenberg Foundation(MMW 20220114)。
文摘Historical documents provide evidence for regional droughts preceding the political turmoil and fall of Beijing in 1644 CE,when more than 20 million people died in northern China during the late Ming famine period.However,the role climate and environmental changes may have played in this pivotal event in Chinese history remains unclear.Here,we provide tree-ring evidence of persistent megadroughts from1576 to 1593 CE and from 1628 to 1644 CE in northern China,which coincided with exceptionally cold summers just before the fall of Beijing.Our analysis reveals that these regional hydroclimatic extremes are part of a series of megadroughts along the Pacific Rim,which not only impacted the ecology and society of monsoonal northern China,but likely also exacerbated external geopolitical and economic pressures.This finding is corroborated by last millennium reanalysis data and numerical climate model simulations revealing internally driven Pacific sea surface temperature variations and the predominance of decadal scale La Ni?a-like conditions to be responsible for precipitation decreases over northern China,as well as extensive monsoon regions in the Americas.These teleconnection patterns provide a mechanistic explanation for reoccurring drought spells during the late Ming Dynasty and the environmental framework fostering the fall of Beijing in 1644 CE,and the subsequent demise of the Ming Dynasty.
