Inland thinning of Pine Island Glacier, West Antarctica

The Pine Island Glacier (PIG) transports 69 cubic kilometers of ice each year from approximately 10% of the West Antarctic Ice Sheet (WAIS). It is possible that a retreat of the PIG may accelerate ice discharge from the WAIS interior. Satellite altimetry and interferometry show that the grounded PIG thinned by up to 1.6 meters per year between 1992 and 1999, affecting 150 kilometers of the inland glacier. The thinning cannot be explained by short-term variability in accumulation and must result from glacier dynamics.     

Accelerated sea-level rise from West Antarctica

Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier thinning rates near the coast during 2002-2003 are much larger than those observed during the 1990s. Most of these glaciers flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.     

Ice flow direction change in interior West Antarctica

Upstream of Byrd Station (West Antarctica), ice-penetrating radar data reveal a distinctive fold structure within the ice, in which isochronous layers are unusually deep. The fold has an axis more than 50 kilometers long, which is aligned up to 45 degrees to the ice flow direction. Although explanations for the fold's formation under the present flow are problematic, it can be explained if flow was parallel to the fold axis approximately 1500 years ago. This flow change may be associated with ice stream alterations nearer the margin. If this is true, central West Antarctica may respond to future alterations more than previously thought.     

An active subglacial water system in West Antarctica mapped from space

Satellite laser altimeter elevation profiles from 2003 to 2006 collected over the lower parts of Whillans and Mercer ice streams, West Antarctica, reveal 14 regions of temporally varying elevation, which we interpret as the surface expression of subglacial water movement. Vertical motion and spatial extent of two of the largest regions are confirmed by satellite image differencing. A major, previously unknown subglacial lake near the grounding line of Whillans Ice Stream is observed to drain 2.0 cubic kilometers of water into the ocean over approximately 3 years, while elsewhere a similar volume of water is being stored subglacially. These observations reveal a wide spread, dynamic subglacial water system that may exert an important control on ice flow and mass balance.     

Cllsworth Mountains: Position in West Antarctica ue to Sea-Floor Spreading

Similarities of middle anld upper Paleozoic deposits of the Ellsworth fountains with those of the Pensacola, Horlick, and other Transtarctic mountains indicate that all these ranges may have had a related geologic history. A native explanation is now suggested which involves sea-floor spreading atnd anslocationi of the Ellsworth crutstal block from its originilal location adjacent to the East Antarctic Shield. Accordingly, the islands of West Antarctica may differ it origin and the Transantarctic Mountains of East Antarctica may represent one margin of an ancient rift.     

吉林省西部盐碱化土地治理对策

本文在分析了吉林省西部盐碱化土地类型、特点及分布的基础上，综合多年研究和生产实践经验，提出了低洼易涝盐碱地发展水田、轻中度盐碱化低产耕地退耕还草、轻中度盐碱化草地围栏封育、重度盐碱化草地人工种草以及盐碱湿地发展芦苇的分类治理对策。     

西部地区土地利用规划约束下的用地策略研究

未来十年,在全国深入实施新一轮西部大开发战略大背景下,西部地区将面临着加快推进工业化、城镇化进程,积极承接东部产业转移的机遇与挑战.土地供需矛盾将日益突出,亟需探索科学、合理的用地策略,促进经济社会可持续发展.文章在阐述西部地区新一轮土地利用总体规划特点基础上,分析规划对西部地区土地利用的影响,以资源紧约束、建设用地供给有限为前提,积极探索科学、合理的用地策略,为西部地区合理利用土地资源提供参考借鉴,对破解土地供需难题,促进西部地区土地资源可持续利用和经济社会可持续发展具有重要的意义.     

Early deglaciation of the labrador shelf

Two marine sediment cores from a basin on the southeastern Labrador Shelf penetrate a mud sequence extending back to 21,000 carbon-14 years before the present (B.P.). The benthic foraminifera are dominated by subartic nearshore species indicative of ice-free summer waters. The pollen record indicates the presence of a sedge-shrub tundra in eastern Labrador as early as 21,000 years B.P. Both sources of evidence suggest less extensive continental ice than has previously been reported for this subarctic region.     

杭州西湖湖西景区土地利用/覆被变化与生态服务价值评估

采用3S技术对杭州西湖湖西综合保护工程实施前后进行对比研究,分析了工程实施前后土地利用/覆被状况和生态系统服务价值的变化。结果表明:2001-2008年,湖西景区未利用地、建设用地和耕地面积减少,草地、林地和水域面积增加。湖西景区年总生态价值从2001年的421.15万元增加到2008年的1 095.59万元,增加了160.14%。表明湖西综合保护工程优化了生态环境和社会环境,是实现区域可持续发展的工程。     

Holocene eruptions of mauna kea volcano, hawaii

Postglacial lava flows, interstratified with thick locally derived sheets of tephra, cover some 27.5 square kilometers on the south slope of Mauna Kea. Most of the volcanics were erupted about 4500 years ago and overlie a regionally extensive paleosol which developed largely during the last glaciation.     

Geomicrobiology of subglacial ice above Lake Vostok, Antarctica

Data from ice 3590 meters below Vostok Station indicate that the ice was accreted from liquid water associated with Lake Vostok. Microbes were observed at concentrations ranging from 2.8 x 10(3) to 3.6 x 10(4) cells per milliliter; no biological incorporation of selected organic substrates or bicarbonate was detected. Bacterial 16S ribosomal DNA genes revealed low diversity in the gene population. The phylotypes were closely related to extant members of the alpha- and beta-Proteobacteria and the Actinomycetes. Extrapolation of the data from accretion ice to Lake Vostok implies that Lake Vostok may support a microbial population, despite more than 10(6) years of isolation from the atmosphere.     

西部欠发达地区耕地动态变化及需求预测研究——以四川省井研县为例

以四川省井研县为例,结合新一轮土地利用总体规划修编,分析了该县域耕地利用中存在的问题,分别采用主成分分析和灰色关联度法分析了井研县耕地利用变化的驱动力;然后,运用灰色系统预测模型,研究其耕地的未来发展趋势,以期掌握其发展动向;最后,以实现耕地总量动态平衡为目标,提出实现土地可持续利用的对策,从而有效地指导当前土地资源管理工作和控制未来的土地利用。这对于促进西部欠发达地区资源、环境和人口的协调与经济可持续发展有着重要意义。     

Holocene eruptive activity of el chichon volcano, chiapas, Mexico

Geologic and radiometric-age data indicate that El Chichón was frequently and violently active during the Holocene, including eruptive episodes about 600, 1250, and 1700 years ago and several undated, older eruptions. These episodes, involving explosive eruptions of sulfur-rich magma and associated dome-growth processes, were apparently separated by intervals of approximately 350 to 650 years. Some of El Chichón's eruptions may correlate with unusual atmospheric phenomena around A.D. 1300 and possibly A.D. 623.     

改良剂对吉林省西部盐碱旱作农田土壤改良的研究

采用石膏、草炭、自制的盐碱改良剂、禾康土壤改良剂对吉林省西部盐碱旱作农田进行改良研究,分析了不同改良剂处理对玉米产量、植株特征及土壤理化性状的影响。结果表明,不同土壤改良剂处理,玉米产量增加,玉米株高、叶面积增加显著;土壤pH均比对照降低、土壤速效养分和有机质增加;土壤阳离子交换量增加,提高了土壤的保肥供肥能力。自制碱性农田土壤改良剂与草炭的改良效果较好,施入自制碱性农田土壤改良剂玉米产量比对照增加了16.3%;施入草炭玉米产量比对照产量增加了8.2%。     

Early reactivation of European rivers during the last deglaciation

During the Last Glacial Maximum, the sea-level lowstand combined with the large extent of the Fennoscandian and British ice sheets led to the funneling of European continental runoff, resulting in the largest river system that ever drained the European continent. Here, we show an abrupt and early reactivation of the European hydrological cycle at the onset of the last deglaciation, leading to intense discharge of the Channel River into the Bay of Biscay. This freshwater influx, probably combined with inputs from proglacial or ice-dammed lakes, dramatically affected the hydrology of the region, both on land and in the ocean.     

Microorganisms in the accreted ice of Lake Vostok, Antarctica

Analysis of a portion of Vostok ice core number 5G, which is thought to contain frozen water derived from Lake Vostok, Antarctica (a body of liquid water located beneath about 4 kilometers of glacial ice), revealed between 2 x 10(2) and 3 x 10(2) bacterial cells per milliliter and low concentrations of potential growth nutrients. Lipopolysaccharide (a Gram-negative bacterial cell biomarker) was also detected at concentrations consistent with the cell enumeration data, which suggests a predominance of Gram-negative bacteria. At least a portion of the microbial assemblage was viable, as determined by the respiration of carbon-14-labeled acetate and glucose substrates during incubations at 3 degrees C and 1 atmosphere. These accreted ice data suggest that Lake Vostok may contain viable microorganisms.     

中西部地区耕地潜力及承载力研究

本文通过机制法、时间序列法计算了中西部地区耕地资源的潜力，分析了未来30年在不同生活标准水平下中西部地区的人口承载力，认为中西部地区棉花、油料供给相对充足，粮食生产基本能满足需求，但近10年内粮食生产要满足小康需求还有一定距离，从全国范围来看近期粮食生产供需较紧．不能因短期粮食供大于求而放松粮食生产．否则将给国民经济带来极为不利的影响。     

Holocene vegetation in chaco canyon, new Mexico

Well-preserved plant remains in packrat middens chronicle vegetation change in Chaco Canyon over the past 11,000 years. Early Holocene evidence of communities dominated by Douglas fir, Rocky Mountain juniper, and limber pine in the San Juan Basin calls for revision of traditional constructs based on fossil pollen. Middle and late Holocene vegetation in the canyon was pinyon-juniper woodland up until Anasazi occupation between 1000 and 800 years ago. Instead of climate, Anasazi fuel needs may explain the drastic reduction of pinyon and juniper after 1230 years ago. The lack of pinyon-juniper recovery over the past millennium has implications for contemporary forest and range ecology.     

浙西山地丘陵地区土地利用地域分区研究——以丽水市为例

为落实土地利用总体规划主体功能分区的思想,采用系统聚类方法,以地处浙江省西部山地丘陵地区的丽水市为研究靶区,选择土地利用自然条件、土地利用结构、土地利用的经济功能、土地利用的社会功能的相关指标,对丽水市进行土地利用地域分区。结果表明,丽水市划分为东部河谷盆地与低山土地利用区、中部河谷盆地与中山土地利用区、西部水系源头和中山土地利用区三大土地利用区;主体功能分区与功域分区相衔接。