硫酸侵蚀碳酸盐岩对长江河水DIC循环的影响

对长江及其主要支流河水水化学和溶解无机碳（DIC）同位素组成（δ13GDIC）进行了研究。河水阳离子组成以Ca^2＋、Mg^2＋为主,阴离子以HCO3-、SO4^2-为主,水化学组成主要受流域碳酸盐岩矿物的化学侵蚀控制。DIC含量为0．3～2．5mmol／L,从上游到河口逐渐降低。δ13CDIC值为-12．0‰-3．4‰,与DIC含量具有相似的变化趋势。H2CO3溶解碳酸盐岩是控制河水DIC来源及其占δGDIC组成的主要机制。H2SO4溶解碳酸盐岩加剧了流域碳酸盐岩的化学侵蚀,一方面导致了河水的DIC含量增加,另一方面也使河水的δ13GDIC值升高。     

DEVELOPMENT OF A DECISION SUPPORT SYSTEM FOR MANAGING PESTICIDE LOSSES IN AGRICULTURAL WATERSHEDS

1 INTRODUCTION Agricultural use of pesticides has been recognized as one of the important non-point pollution sources in the world, and the pesticide application to agricultural lands has led to large amounts of residues discharged into surface water through runoff (Leonard, 1990). There have been growing concerns about the fate and transport of pesticides in agricultural lands, due to the associated adverse impacts on water environment and human health (Agassi et al., 1995; Ng and Clegg…     

伊利诺斯盆地宾夕法尼亚纪沉积物季节性降雨的证据

伊利诺斯盆地宾夕法尼亚纪沉积物季节性降雨的证据ＥｒｉｋＰ．Ｋｖａｌｅ等根据古纬度位置、动物群证据或气候敏感岩性的出现而恢复的古气候可表达一个地区相当长时期的气候格局，但气候的细节只有通过与目前条件相同地区的比较才能推断。由于时间的迁移、海洋和陆地的变...     

A SIMPLIFIED APPROACH TO MODELING 3D SEDIMENT-LADEN TURBULENT FLOWS

ＡＳＩＭＰＬＩＦＩＥＤＡＰＰＲＯＡＣＨＴＯＭＯＤＥＬＩＮＧ３ＤＳＥＤＩＭＥＮＴ－ＬＡＤＥＮＴＵＲＢＵＬＥＮＴＦＬＯＷＳＤｏｎｇｈｕｏＺＨＯＵａｎｄＳａｍＳ．Ｙ．ＷＡＮＧＡｂｓｔｒａｃｔ：Ａ３－ｄｎｕｍｅｒｉｃａｌｍｏｄｅｌｆｏｒｓｉｍｕｌａｔｉｎｇｓ...     

金属矿床中铀的来源

在目前开釆的許多矿床中,鈾的来源并不清楚,因而在成因上尚存在着許多不一致的假說。最流行的两种假说是:鈾是通过普通地下水从碎屑岩或火成岩中淋滤而来;鈾在晚期残余流体中从花崗岩浆或鹼性岩浆析出。經过慎重考証后发現,即使有属于对普通碎屑岩或火成岩的淋滤形成的矿床,也只是极少数,而許多矿床則是金属矿床中鈾的再分佈結果或是早先由上升溶液所形成的富集物。最近工作表明,上升溶液在花崗岩形成以前很早就由岩浆开始析出,可能一直断断續續到分离結晶結束为止。含鈾溶液从岩浆的析出和輝綠岩与煌斑岩脈的侵入似乎在同时一期。从較酸性的岩浆分異体中析出的鈾似乎比重不大。后生鈾矿床和各种类型火成岩侵入体以及主要构造单元之間的空間关系有力地說明了在大多数地区鈾都产于相当深的地方,这些矿床中的金属組合只能用这种假設才可得到解释。地表水只能淋滤和再分佈某些类型矿床中的內生鈾及其伴生金属,例如,在科罗拉多高原的那些矿床或气候干燥地区矿脈的上部。     

ПР-10型高速冲击凿岩机

苏联现时最轻的凿岩机是列宁格勒风动工具厂出产的РПМ-17型,重量17公斤。为了满足矿工们与矿井建设者们的愿望,克里沃罗格共产党人工厂的工作人员设计并制造了一种重量轻而高速冲击的手提式ПР-10型凿岩机,重量为10公斤（图1）,其生产能力与重量为23公斤的ПА-23型凿岩机相同。     

Hydrogeochemical controls on surface and groundwater chemistry in naturally acidic, porphyry-related mineralized areas, southern Rocky Mountains

In southern Rocky Mountains, catchments characterized by acidic, metalliferous waters that are relatively unaffected by human activity usually occur within areas that have active or historical mining activity. The US Geological Survey has utilized these mineralized but unmined catchments to constrain geochemical processes that control the surface- and ground-water chemistry associated with near surface acid weathering as well as to estimate premining conditions. Study areas include the upper Animas River watershed, Lake City, Mt. Emmons, and Montezuma in Colorado and Questa in New Mexico. Although host-rock lithologies range from Precambrian gneisses to Cretaceous sedimentary units to Tertiary volcanic complexes, mineralization is Tertiary in age and associated with intermediate to felsic composition, porphyritic plutons. Pyrite is ubiquitous. Variability of metal concentrations in water is caused by two main factors： mineralogy and hydrology. Parameters that potentially affect water chemistry include： host-rock lithology, intensity of hydrothermal alteration, sulfide mineralogy and chemistry, gangue mineralogy, length of flow path, precipitation, evaporation, and redox conditions. Springs and headwater streams have pH values as low as 2.5, sulfate up to 3700 mg/L and high dissolved metal concentrations （for example： Al up to 170 mg/L; Fe up to 250 mg/L; Cu up to 3.5 mg/L and Zn up to 14 mg/L）. With the exception of evaporative waters, the lowest pH values and highest Fe and Al concentrations occur in water draining the most intense hydrothermally altered areas consisting of the mineral assemblage quartz-sericite-pyrite. Stream beds tend to be coated with iron floc, and some reaches are underlain by ferricrete. When iron-rich ground water interacts with oxygenated waters in the stream or hyporheic zone, ferrous iron is oxidized to ferric iron, which is less soluble, leading to the precipitation of iron oxyhydroxides.     

Re-Os Age of Cu-Ni Ores from the Huangshandong Cu-Ni Sulfide Deposit in the East Tianshan Mountains and Its Implication for Geodynamic Processes

An isochron age of 282±20 (95% conf. limit) Ma of the sulfide ores in the Huangshandong Cu-Ni sulfide deposit, the East Tianshan Mountains has been obtained through Re-Os isotopic measurement. The age implies that the Cu-Ni sulfide deposit and other related deposits in the same area occurred in a Permian extensional environment of post-collision instead of Devonian-Early Carboniferous ophiolite-related oceanic or island arc environments inferred before. It shares the same ages with the orogenic and epithermal gold deposit systems in the same area. An initial 187Os/188Os ratio of 0.25±0.04 (1σ) and a γos value of 99 on average display the participation of large quantities of crustal components into the rock-forming and ore-forming system during mineralization and magmatic emplacement.     

表生风化作用下多年冻土土壤的理论粒径分布

The paper discusses the distinctive features of grain size distribution of permafrost soils formed under conditions of continental lithogenesis and cryogenic weathering of rocks. As a functional consequence of surface erosion of mineral particles, the log-normal distribution of the density function of grain size is derived confirmed for any conditions and sediment types.