Attenuation of aqueous metal transport at two natural acid rock drainage occurrences in the Yukon Territory, Canada     

Y.T. John Kwong 《中国地球化学学报》2006,25(B08):229-230

Naturally acidic drainage associated with pyritic black shale has been observed in many locations in the Yukon Territory. While not necessarily linked to known mineral deposits, most of these natural acid rock drainage occurrences show elevated dissolved concentrations of trace elements, especially zinc, nickel, copper, cadmium and arsenic. Based on field observations, microbial investigation, chemical analyses and geochemical modeling, the fate and transport of potentially deleterious elements at two natural acid drainage occurrences with slightly different settings are examined. The Macintosh Creek is a small, acidic stream （pH 2.98-3.40）, 2 km long, located in the Macmillan Pass area of east-central Yukon amidst known sedimentary exhalative massive sulfide mineralization but remains undisturbed by exploration activities. Its trace metal content is apparently derived from groundwater discharges, which gave as much as 5.0, 2.5, 0.7, 0.13 and 0.03 mg/L ofZn, Ni, Cu and As, respectively. Interaction and sorption reactions with algal mats, biofilms and iron oxyhydroxides appear to be the dominant mechanisms attenuating aqueous contaminant transport along the stream. Cryogenic precipitation further consolidates the ferricrete formation and reduces the mobility of the sorbed metals. The tributaries of the Engineering Creek along the Dempster Highway in northern Yukon drain through a series of dolomite, phyllite, argillite, limestone, black shale, sandstone and conglomerate with no known concentration of mineralization. In this area, the water chemistry fully reflects the local geology with acidic streams invariably associated with black shale occurrences. Groundwater seeps in the headwaters area of the km-180 Creek completely enclosed in black shale gave pH 3.0 and as much as 148, 39, 2.9 and 9.1 mg/L of Zn, Ni, Cu and As, respectively. Sorption with iron oxyhydroxide and organic matter appear to dominate the attenuation of contaminant transport along the stream. However, once entered into carbonate-dominated terrains, secondary carbonate minerals exercise additional geochemical control on the local water chemistry as a result of neutralization.  相似文献   

Naturally acidic and metalliferous waters at unmined volcanogenic massive sulfide deposits in the Bonnifield mining district, Alaska Range, east-central Alaska     

Robert G. Eppinger Paul H. Briggs Cynthia Dusel-Bacon Stuart A. Giles Larry P. Gough Jane M.Hammarstrom Bernard E. Hubbard 《中国地球化学学报》2006,25(B08):232-232

The Bonnifield district hosts 26 tmmined volcanogenic massive sulfide （VMS） occurrences. Environmental geochemical samples of water and stream sediment were collected at several occurrences, concentrating on the two best-exposed and largest deposits, Red Mountain （RM） and Sheep Creek （SC）. Limited samples were also collected at the poorly exposed WTF deposit. The deposits are Late Devonian to Early Mississippian, and are hosted by felsic metavolcanic and carbonaceous schist members of the Totatlanika Schist or Keevy Peak Fm. Spring and stream waters at RM and SC have pH values commonly 〈3.5 （as low as 2.4 at RM and 2.5 at SC）, high conductivity （up to 11000 μS/cm）, and very high （Is to 100s mg/L） dissolved contents of Al, Cd, Co, Cu, Fe, Ni, and Pb. Waters at RM are characterized by extremely high REE contents （summed REE median 3200 μg/L, n=33）. At both RM and SC, pyrite oxidation and dissolution produce low pH waters that interact with and dissolve bedrock minerals, resulting in acidic, metal-laden, naturally degraded streams that are mostly devoid of aquatic life. Ferricrete is common. In contrast, WTF barely produces a surficial environmental footprint, mostly due to topography and relief. RM and SC are well exposed in the areas of relatively high relief, and both exhibit extensive areas of quartz-sericite-pyrite-alteration. While WTF shares many of the same deposit-and alteration characteristics, it is concealed by tundra in a large, nearly flat area. Surface water at WTF is absent and outcrops are sparse. Even though WTF is roughly the same size as Red Mountain （both around 3 million tonnes） and has similar base- and precious-metal grades, the surficial geochemical manifestation of WTF is minimal. However, exposure through mining of the altered, mineralized rock at WTF potentially could initiate the same processes of pyrite oxidation, acid generation, and mineral dissolution that are observed naturally at RM and SC.  相似文献   

关于高中地理入门学习的几点建议     

杨富民  霍学英 《地理教学》2006,(4):21-22

俗话说：“万事开头难”。对于初学高中地理的学生来说，难就难在开头，即“行星地球”和“地球上的大气”两章。笔在多年的教学实践中发现，从高中地理的学习开始，往往形成“两极分化”的格局，一极是部分“开头”开得好的学生，领悟到了学习高中地理的方法和技能，以后的学习可以说“一路顺风”，成绩保持得很好；而另一极则是部分学生在开头就被迎头一棒，进而丧失了学习地理的信心和兴趣。如何帮助学生开好这个头，让学生迈过“门槛”，激发学习地理的兴趣，笔认为必须注重培养学生五个方面的学习能力。  相似文献   

设计出让学生喜欢的地理试卷     

廖书庆 《地理教学》2006,(6):28-30

地理考试是地理学习的延伸，也是目前地理学习评价的一种主要方式。高中新课改一年来，老师在探索课堂上如何让学生喜欢学习、主动学习、渴望学习地理方面花了不少气力，但却很少有人关注如何让学生喜欢考试、渴望考试。《普通高中新地理课程标准》指出：地理学习应“关注基础性、时代性，密切与现实生活和社会发展的联系，使学生增强学习能力和生存能力”；地理考试“要加强对地理知识的理解和运用，提高获取和处理地理信息的能力”。  相似文献   

“香港”一节的探究教学与反思     

贾笑玲 《地理教学》2006,(10):28-29

以培养学生创新精神和实践能力为重点的素质教育，强烈冲击着人们头脑中陈旧的思想和意识，特别是新课程所倡导的自主、探究式学习，给地理教学注入了新鲜的空气，但学习方式到底怎样转变？怎样才能让学生成为一个知识的发现、探索？恰逢我校进行“探究式教与学”课题研究，这给在摸索中前进的我指明了方向，我便借课研东风，调整、加速了自己教改步伐，尤其一节“香港”的教学，更使我豁然开朗，信心倍增。  相似文献   

建设电子政务 提高执政能力     

杨泽 《中国地名》2006,(1)

建设电子政务是提高执政能力的客观要求,也是提高执政能力的重要手段。  相似文献   

我国城市抗灾能力脆弱     

《地理教学》2006,(10):44-45

北京市逢雨就堵车，烟台和威海2005年罕见的城市雪灾，去年的松江水污染事件，城市里爆发的非典疫情、禽流感疫情……这一连串的事件引发了各界对于中国城市灾害和公共安全的广泛关注。在8月22日举行的中国市长协会第四次市长代表大会上。正式发布的《中国城市发展报告（2005）》指出，近年来我国城市各类安全危机的爆发数量持续攀升，但现有减灾水平还远不能满足经济社会发展的需要，我国城市的救灾储备能力远远滞后于城市发展水平。  相似文献   

国务院关于加强地质工作的决定     

《核地知与行》2006,(2):14-18

各省、自治区、直辖市人民政府，国务院各部委、各直属机构：地质工作是经济社会发展重要的先行性、基础性工作，服务于经济社会的各个方面。贯彻党的十六届五中全会精神，全面落实科学发展观，构建社会主义和谐社会，对地质工作提出了新的更高的要求。为了全面增强地质勘查的资源保障能力和服务功能，促进地质工作更好地满足经济社会发展的需要，现作出如下决定。  相似文献   

Influence of heavy metals and pH on sulfate reduction metabolism     

《中国地球化学学报》2006,25(B08):130-130

  相似文献   

信息之花任采撷--吉林省测绘局信息系统应用开发一瞥     

刘子刚  张树林 《中国测绘》2005,(2):28-31

吉林,地处东北,是我国的老工业基地之一。在区域经济较之沿海发展较缓的情况下,吉林的测绘事业却在韩来发局长的带领下,排除前进中的各种困难,开拓创新,锐意进取,取得了跨越式的发展。如今的吉林省测绘局,测绘生产方式发生了根本性转变,测绘科技实力显著增强,生活环境优美舒适,干部职工的精神面貌焕然一新,对测绘事业的前途充满信心,呈现出一派勃勃生机。新春佳节一过,记者便迎着瑞雪,踏上行程,前往吉林去探寻那跨越式发展的奥秘。  相似文献