浅水湖泊水上煤田钻井液污染分析

为了研究浅水湖泊水上煤田钻探工程中可能发生的钻井液泄漏对水体的污染情况,以淮南顾北矿港河水上勘探为例,实测分析了不同浓度钻井液对污染指标和鲫鱼存活的影响,其中污染指标包括pH值、悬浮物、CODcr、总Cr和Cd。采用保守物质的对流扩散方程,对钻井液输移扩散进行了数值模拟。研究发现,当钻井液浓度小于1 000mg/L时,所测试的污染指标基本上能够达到二级排放标准;当钻井液浓度达到5000mg/L时,鲫鱼死亡率约为原水中养殖的正常死亡率的2倍;钻井液在扩散初期其浓度迅速减少,且水流整体流速越大,则钻井液扩散越快,在扩散后期钻井液会形成高浓度聚集区,钻井液浓度的衰减变慢。     

Geochemistry of dust aerosol over the Eastern Pamirs

The Pamirs are situated in the inner part of the Asian continent, a region which plays a critical role in Asian dust emission and transport. This study measured the elemental composition of atmospheric dust aerosol samples collected during the period between July 2004 and April 2006 at Mt. Muztagata, Eastern Pamirs, at a high-altitude (38°17′N, 75°01′E, 4430 m). The Muztagata aerosol samples show Ca/Al (∼0.7) and Fe/Al (∼0.7) ratios that are distinguishable from those from other sites. The La/Th ratios (averaging 2.30-2.36) and Th/U ratios (averaging 2.75-3.11) indicate typical eolian deposition. The dust aerosol samples have very similar rare earth element (REE) patterns, with relative enrichment of light REE, a slight depletion of heavy REE, and a strongly negative europium anomaly (δEu values averaging 0.65). The Muztagata dust shows homogeneity of composition during the sampling period, with minor variations due to seasonal effects and possible different air mass, suggesting the possibility of a well-mixed atmospheric background dust on a regional scale. The zonal Westerlies dominate and the longitude circulations are relatively very weak for dust transport dynamics in the Pamirs and Tien Shan regions. Our results demonstrate a distinct difference in elemental composition between dust over the Eastern Pamirs and that over Inilchek, Central Tien Shan, indicating that the Asian dust emission regions have great variations in their chemical properties, and provide a better constraint on the climatic impact of Asian dust.     

川中丘陵区红层紫色土对果树的生态效应分析

川中丘陵区红色岩层（红层）主要为侏罗系、白垩系地层，其风化岩体衍生的紫色土是最重要和极关键的果园土壤，对区内果树具有复杂的生态效应特征。     

Temperature and methane records over the last 2 ka in Dasuopu ice core

High resolution δ¹⁸O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas. Analysis shows that the δ¹⁸O record correlates well with the Northern Hemispheric temperature, Dunde ice core record, and with temperature record in eastern China. The warming trend detected in δ¹⁸O record from the last century is similar to that during the Medieval warm period. There is a dramatic increasing in methane concentration in the Dasuopu ice core, which reached 1031 nmol ⋅ mol^-1 in 1997. Moreover, methane concentration in the Dasuopu ice core is about 15%-20% higher than that in Antarctica and Greenland. There is a positive correlation between methane concentration and δ¹⁸O in Dasuopu ice core.     

A comprehensive literature review of the demand forecasting methods of emergency resources from the perspective of artificial intelligence

Natural Hazards - In recent decades, several forecasting methods have been proposed so as to aid in selecting from all optimal alternatives in the demand of emergency resources. Academic research...     

藏南冰前湖枪勇错近百年沉积速率变化及冰川进退反演

青藏高原上分布着大量的大陆性冰川,其对区域及全球气候变化响应极其敏感.工业革命以来,随着全球升温速率加快(特别是北半球),青藏高原部分地区的冰川在近百年显著退缩.冰前湖沉积物是最直接的冰川变化记录载体之一,但其沉积速率如何响应冰川及气候变化,能否反演冰川进退过程却知之甚少.本文依据~(210)Pb和~(137)Cs限定藏南冰前湖枪勇错QY5沉积岩芯的年龄,计算出不同深度沉积物的沉积速率,且与前人(QY-3)的沉积速率进行对比,揭示了近百年来枪勇错流域冰川变化历史及其与气温之间的关系.结果表明,枪勇错QY5近百年来的平均沉积速率为0.21 cm/a,比湖心(QY-3)快2倍左右,但两者的变化基本同步,高沉积速率对应温度上升期,是冰川退缩的直接响应:(1)1900—1960年,枪勇错沉积速率整体增加且变幅较大,与1890—1950年之间西藏温度波动式升高相对应,反映枪勇冰川总体处于退缩状态;(2)1960—1985年,沉积速率低且变幅较小,同期气温下降,枪勇冰川退缩程度相对较低且保持平稳;(3)1985年以来,枪勇错沉积速率呈上升趋势,是全球增暖下冰川显著退缩的直接响应.在短时间尺度内冰前湖沉积速率所揭示的枪勇冰川变化主要受控于温度,降水量对冰川变化的影响较小,但冰川对温度变化的响应滞后5～10 a.由于全球变暖和冰川对温度响应的滞后,在未来几十年高原冰川的融化速率可能会加快,亚洲水塔将面临着新的挑战.     

青藏高原南部空姆错湖芯中陆源正构烷烃氢同位素比值的气候意义

在青藏高原南部空姆错钻取了一根浅湖芯,对其中时间跨度约为50年的剖面按7年间隔对其中陆源正构烷烃(C_(25),C_(27),C_(29),C_(31))进行了提取分析。通过将这些生物标志物的氢同位素比值与附近浪卡子气象站和拉萨气象站的气象参数记录进行比较,发现这些生物标志物的δD值与生长季节时段的平均气温显著相关,而与生长季节时段的降雨量和相对湿度的相关性差,说明陆源沉积正构烷烃的氢同位素比值主要记录了气温信号,可以被用于古温度重建。     

一种新的混合迭代UKF

从统计线性回归的角度对无味变换(unscented transformation,UT)进行分析,推导了迭代无味卡尔曼滤波(iterated unscented Kalman filter,IUKF)。针对IUKF计算量大的问题,结合弦线迭代法和IUKF,得到了一种新的混合迭代无味卡尔曼滤波器。数值仿真的结果表明,新滤波算法的精度优于扩展卡尔曼滤波、迭代扩展卡尔曼滤波和无味卡尔曼滤波,并可以有效降低IUKF的计算量。     

Atmospheric Methane in Ice Cores

The reconstruction of air trapped in ice cores provides us the most direct information about atmospheric CH4 variations in the past history. Ice core records from the ＂Three Poles （Antarctica, Greenland and Tibetan Plateau）＂ reveal the detailed fluctuations of atmospheric CH4 concentration with time and are allowed to quantify the CH4 differences among latitudes. These data are indispensably in the farther study of the relationship between greenhouse gases and climatic change, and of the past changes in terrestrial CH4 emissions. Ice cores reconstruction indicates that atmospheric CH4 concentration has increased quickly since industrialization, and the present day＇s level of atmospheric CH4 （1800 ppby） is unprecedented during the past Glacial-Interglacial climate cycles.     

210Pb和137Cs定年技术在湖泊沉积物中的应用与问题

湖泊沉积记录研究对了解流域侵蚀、揭示区域气候环境变化及人类活动影响、建立外生地球化学循环模式等均具有重要意义.放射性同位素~(210)Pb和~(137)Cs组合定年法是百年尺度湖泊沉积记录研究的首选方法,在过去几十年中得到了广泛应用,大力推动了湖泊沉积记录的高分辨率气候环境变化研究的开展.然而,如何理解和选择适用的计算模式来尽可能地提高定年准确度目前仍存在争议,这在一定程度上限制了该方法的应用.鉴于上述问题,本文基于本实验室近年来从青藏高原获取的若干支代表性湖芯的定年结果,从样品前处理、仪器及测试、数据分析及计算等全过程对~(210)Pb、~(137)Cs定年原理和方法进行了较为系统的阐述;在此基础上,提出了~(210)Pb定年样品封装原则,探讨了高纯锗γ谱仪在放射性活度测量中的影响因素,并建立了准确有效的比活度校正方法;明确指出了恒定初始浓度模式(constant initial concentration,CIC)可用于计算沉积物每层的年龄,而不是部分研究中认为的平均沉积速率,这对于深刻理解该定年模式并提供准确的定年结果具有重要的参考意义.同时,通过对比两种放射性核素的分布特征发现,相对于~(210)Pb而言,~(137)Cs更容易发生垂向迁移进而影响其时标准确性,这需引起研究者的充分重视,因此,当二者定年结果出现明显差异时,建议以~(210)Pb定年结果为准.