青藏高原多年冻土区土壤需氧可培养细菌多样性及群落功能研究

以青藏高原腹地不同植被类型多年冻土区土壤细菌为研究对象, 分析了可培养菌群数量、 多样性和生理代谢功能的变化及其与环境因子间的关系. 结果显示: 从沼泽草甸到高寒荒漠, 土壤水分、 总碳、 总氮含量逐渐降低, pH值升高, 可培养细菌数量在2.97×10⁶~2.88×10⁷ CFU·g^-1, 与含水量、 总碳、 总氮显著正相关; Actinobacteria(51.4%)和γ-Proteobacteria(31.7%)为优势菌群, α-protebacteria仅在沼泽草甸中有分布, β-protebacteria、 Bacterioidetes丰度与含水量、 总碳、 总氮间显著正相关; 自沼泽到荒漠, 菌群代谢活性和Shannon功能多样性指数降低, pH与Shannon指数显著负相关, 继氨基酸类碳源之后, 多聚物逐渐成为被细菌群落主要利用的碳源种类. 研究表明, 伴随冻土退化地上植被逆向演替的过程, 青藏高原多年冻土地下土壤微生物群落丰度、 遗传和代谢功能多样性均发生了不同程度的响应.     

漳河流域近60年径流变化分析

近年来,漳河流域径流量显著减少,严重影响流域内水资源的开发与利用。采用多种数理统计方法,分析了径流量的演变特征。结果表明:漳河流域年径流量呈显著性减少趋势,其中下游减少的趋势更加显著;20世纪80年代以前年径流量高于多年平均值,80年代以后低于多年平均值,且不同年代变幅较大;漳河流域实测径流量在20世纪70年代中后期出现变异点,变异点之后年径流量比变异点之前明显偏小。径流量系列存在6~7a的准周期。     

Intensification of the East Asian Monsoon in Southern China at about 300–400 kaBP Inferred from Eolian Deposits in the Middle-lower Reaches of the Yangtze River

In the East Asian monsoon region,eolian deposits widely distributed in the middle-lower reaches of the Yantgze River are among the best materials available for studies on Quaternary climate change in the subtropical zone of Southern China.Typical eolian deposits in this region include upper Xiashu Loess(XL) and underlying Vermiculated Red Soil(VRS) layers.In this paper,chronological and paleoclimatic studies are conducted on an eolian deposit sequence near Jiujiang(JJ) city in northern Jiangxi province.A magnetostratigraphic study,combined with optically stimulated luminescence(OSL) dating,is conducted on the JJ section and provides further evidence that eolian deposits in the middle-lower reaches of the Yangtze River have been formed since the late Early Pleistocene,and that the boundary age between the XL and VRS layers is about 300-400 kaBP.In grain-size records of the JJ section,the median grain-size and content of the 30 μm size fraction increase sharply after 300-400 kaBP,representing an East Asian winter monsoon intensification event.Further pollen analysis reveals differing pollen assemblages before and after 300-400 kaBP:there is an evident increase in plants adapted to grow in a warm humid environment after 300-400 kaBP,implying an increase in precipitation caused by intensification of the East Asian summer monsoon.Global ice volume and uplift of the Tibet Plateau(TP) are regarded as crucial factors influencing variations of the East Asian monsoon on a long-term scale.The deep-sea δ~(18)O record,which reflects variations in global ice volume,shows no obvious change after 300-400 kaBP.Moreover,the influence of global ice volume changes on the East Asian summer and winter monsoons is inverse;the global ice volume increase(decrease) implies a strengthened(weakened) winter monsoon and weakened(strengthened) summer monsoon.We therefore interpret the coupled intensifications of the East Asian summer and winter monsoons at about 300-400 kaBP to the uplift of the TP in the Middle Pleistocene.This climate event is also documented in eolian deposits from the southern margin of the Chinese Loess Plateau(CLP) and from the desert-loess transitional belt.However,it is not recorded in the loess-paleosol sequences from the central part of the CLP,thereby indicating differing climate responses to TP uplift in different regions,which requires further study.     

碳酸盐预分离-紫外脉冲荧光法快速测定高硬度地下水中微量铀

建立了碳酸盐预分离-紫外脉冲荧光法快速测定高硬度地下水中微量铀的方法。试验发现,预先向20.00mL高硬度水样中加入70mg·mL~(-1)的碳酸钠溶液1.20mL,将大部分共存的Ca~(2+)和Mg~(2+)以碳酸盐沉淀的形式与UO_2(CO_3)_2~(2-)有效分离后,应用紫外脉冲荧光法测量铀浓度,不但溶液保持澄清,pH值也可保持在7~9的约束范围之内。该预处理程序简单快速,测量结果准确可靠。方法的检出限为0.02μg·L~(-1),全程加标回收率在99%~101%之间,测量结果的相对标准偏差(RSD)小于5%。     

水泥-粉煤灰浆液在水电站隧洞灌浆中的应用

针对三叉水电站引水隧洞Ⅳ标段围岩地质条件,详细分析了水泥-粉煤灰浆液在该工程引水隧洞灌浆中的应用情况。从应用情况综合分析可以得出,隧洞灌浆采用水泥-粉煤灰浆液是可行的,完全能满足设计要求,在保证灌浆质量的前提下,可以降低部分施工成本,具有较好的推广应用价值。     

西藏改则洞错地区白垩纪火山岩锆石U-Pb年代学、Hf同位素组成及对班公-怒江洋俯冲闭合的制约

班公湖—怒江缝合带是青藏高原内一条重要的缝合带,其俯冲极性和闭合时限一直存在着争议,这无疑限制了我们对青藏高原演化历史的认识。本文对仲岗安山玄武岩和一套新发现的晚白垩世安山岩进行研究,获得了其锆石U-Pb年龄分别为123.75±0.92 Ma和74.23±0.76 Ma。仲岗安山玄武岩锆石的ε_(Hf)(t)值为-7.3~+4.4,具有岛弧玄武岩特征,指示班公湖—怒江洋盆在该地区仍然继续向北俯冲;晚白垩世安山岩锆石的ε_(Hf)(t)值为+3.1~+11.1,其可能是亏损地幔混熔了部分的陆壳物质而形成的,且不整合在蛇绿岩之上。结合区域资料本文认为班公湖—怒江洋盆在改则地区的闭合时限在100~75 Ma之间。     

对燕山辽西地区构造格局的认识和讨论

燕山辽西地区的盖层可分两个构造层,由燕辽复向斜和秦皇岛背形相互叠加,并相应发育两期推覆构造。复向斜范围包括内蒙地轴和燕山沉降带,是由长条形的三个背斜和二个向斜相间,及配套的EW向纵断裂、SN向横断裂和NE向、NW向的共轭断裂组成。著名的尚义-宽城-凌源-朝阳-北票断裂是复向斜及其次级背斜的轴部纵断裂,以南大岭组、窑坡组和北票组作为其裂隙充填物。燕山EW向断裂南北对冲现象是复向斜纵断裂放射状排列并向核部推覆的反映。复向斜的形成机制完全符合纵弯褶皱作用下岩石的变形原理,是西伯利亚板块和华北板块碰撞的结果;秦皇岛背形的形成是后期太平洋板块俯冲在欧亚板块之下所致。     

水热条件下黄铁矿片、板状晶体的微结构

利用透射电子显微镜(TEM)系统观测了黄铁矿片、板状晶体的微结构,发现在水热条件下生成的黄铁矿片、板状晶体具有正方形、矩形等多种形貌。其中,正方形较多,矩形次之,另可见到一些其他不规则形状。黄铁矿片、板状晶生长完好,未见缺陷。经测定多数四边形片状黄铁矿的两组边分别平行(010)和(100),其生长晶面为(001);个别四边形片状黄铁矿的两组边分别平行(010)和(101),其生长晶面为(101),矩形片状黄铁矿长轴生长方向为001。在水热条件下黄铁矿以多形貌出现,黄铁矿的片、板状晶体多数是沿(001)面生长的结果,(001)为黄铁矿片、板状晶体的主要二维生长面,并沿001方向扩展,构成了二维晶体。     

Downstream patterns of bed sediment-borne metals,minerals and organic matter in a stream system receiving acidic mine effluent: A preliminary study

Different downstream variation patterns were observed for a range of bed sediment-borne metals (aqua regia-extractable fraction) in a subtropical stream system receiving acid mine drainage. Mine-originated Fe tended to be deposited in the acidic (mean pH < 4.9) upstream reach in forms of goethite and/or hematite. In contrast, other metals tended to be transported farther downstream and settled in a low-gradient reach with high pH (mean pH > 5.6). The peak of sediment-borne Al, Be, Ca, Cd, Co, Cu, La, Mn, Ni and Zn corresponded very well with the peak of the sediment-borne organic matter, suggesting a close association between the water-borne organic colloids and the inorganic metal oxides/hydroxides during their transport. The marked increase in the sediment-borne Al and Pb started more upstream than the other metals, suggesting that the water-borne Al and Pb were more susceptible to pH rise-induced precipitation, as compared to the other metals. It appeared that the organic colloids played no important role in Pb transport and settlement. The iron precipitates had a limited role to play in affecting the transport and fates of other metals since they were predominantly formed and deposited in the acidic reach, which made them incapable of scavenging cationic metals by co-precipitation or adsorption.     

新疆若羌县黑山梁地区北山岩群地质特征及构造环境

北山岩群是一套经角闪岩相主期变质作用和绿帘角闪岩相退变质作用的强变质变形地体.据岩石组合特征可划分为4个岩组:第一岩组为斜长角闪片岩夹黑云斜长片麻岩和变粒岩;第二岩组为片麻岩夹斜长角闪片岩、石英片岩、变粒岩;第三岩组为石英片岩夹大理岩、石英岩;第四岩组为石英岩夹石英片岩.经原岩恢复,第一岩组原岩主要为板内拉斑玄武岩,具向岛弧玄武岩过渡趋势;第二岩组原岩为快速沉积的碎屑岩和酸性火山岩;第三岩组原岩为碎屑岩夹碳酸盐岩;第四岩组原岩为成熟度较高的碎屑岩.据火山岩组合、碎屑组合岩特征及地球化学特征,判断其形成年代为早元古代,构造环境为早期裂谷发育速度较快,火山活动强烈,沉积物为快速沉积的碎屑岩;后期构造趋于平缓,碎屑岩成熟度升高,并夹有厚层碳酸盐岩.