美国西部克罗拉多Cripple Creek地区浅成低温金-碲化物矿床成因及相关之碱性火成岩

美国西部克罗拉多ＣｒｉｐｐｌｅＣｒｅｅｋ地区浅成低温金－碲化物矿床成因及相关之碱性火成岩自１８９１年发现至今，ＣｒｉｐｐｌｅＣｒｅｅｋ地区已产金６５３ｔ之多，成为全美第二大金产地．金矿床产于被元古宙基底岩石包围着的狭小的（１８ｋｍ２）渐新统火山杂岩中...     

Testing the utility of structure‐from‐motion photogrammetry reconstructions using small unmanned aerial vehicles and ground photography to estimate the extent of upland soil erosion

Quantifying the extent of soil erosion at a fine spatial resolution can be time consuming and costly; however, proximal remote sensing approaches to collect topographic data present an emerging alternative for quantifying soil volumes lost via erosion. Herein we compare terrestrial laser scanning (TLS), and both unmanned aerial vehicle (UAV) and ground photography (GP) structure‐from‐motion (SfM) derived topography. We compare the cost‐effectiveness and accuracy of both SfM techniques to TLS for erosion gully surveying in upland landscapes, treating TLS as a benchmark. Further, we quantify volumetric soil loss estimates from upland gullies using digital surface models derived by each technique and subtracted from an interpolated pre‐erosion surface. Soil loss estimates from UAV and GP SfM reconstructions were comparable to those from TLS, whereby the slopes of the relationship between all three techniques were not significantly different from 1:1 line. Only for the TLS to GP comparison was the intercept significantly different from zero, showing that GP is more capable of measuring the volumes of very small erosion features. In terms of cost‐effectiveness in data collection and processing time, both UAV and GP were comparable with the TLS on a per‐site basis (13.4 and 8.2 person‐hours versus 13.4 for TLS); however, GP was less suitable for surveying larger areas (127 person‐hours per ha^?1 versus 4.5 for UAV and 3.9 for TLS). Annual repeat surveys using GP were capable of detecting mean vertical erosion change on peaty soils. These first published estimates of whole gully erosion rates (0.077 m a^?1) suggest that combined erosion rates on gully floors and walls are around three times the value of previous estimates, which largely characterize wind and rainsplash erosion of gully walls. Copyright © 2017 John Wiley & Sons, Ltd.     

Acidification of Earth: An assessment across mechanisms and scales

In this review article, anthropogenic activities that cause acidification of Earth’s air, waters, and soils are examined. Although there are many mechanisms of acidification, the focus is on the major ones, including emissions from combustion of fossil fuels and smelting of ores, mining of coal and metal ores, and application of nitrogen fertilizer to soils, by elucidating the underlying biogeochemical reactions as well as assessing the magnitude of the effects. These widespread activities have resulted in (1) increased CO₂ concentration in the atmosphere that acidifies the oceans; (2) acidic atmospheric deposition that acidifies soils and bodies of freshwater; (3) acid mine drainage that acidifies bodies of freshwater and groundwaters; and (4) nitrification that acidifies soils. Although natural geochemical reactions of mineral weathering and ion exchange work to buffer acidification, the slow reaction rates or the limited abundance of reactant phases are overwhelmed by the onslaught of anthropogenic acid loading. Relatively recent modifications of resource extraction and usage in some regions of the world have begun to ameliorate local acidification, but expanding use of resources in other regions is causing environmental acidification in previously unnoticed places. World maps of coal consumption, Cu mining and smelting, and N fertilizer application are presented to demonstrate the complex spatial heterogeneity of resource consumption as well as the overlap in acidifying potential derived from distinctly different phenomena. Projected population increase by country over the next four decades indicates areas with the highest potential for acidification, so enabling anticipation and planning to offset or mitigate the deleterious environmental effects associated with these global shifts in the consumption of energy, mineral, and food resources.     

Turkey Lakes Watershed,Ontario, Canada: 40 years of interdisciplinary whole-ecosystem research

The Turkey Lakes Watershed (TLW) study is a federal, interdepartmental study established in 1979 to investigate the effects of acid rain on terrestrial and aquatic ecosystems. The 10.5 km² watershed, located in the Eastern Temperate Mixed Forest on the Canadian Shield, has been the site of multidisciplinary studies on biogeochemical and ecological processes conducted across plot to catchment scales. The whole-ecosystem investigative approach was adopted from the outset and has allowed research to evolve from its original (and continuing) acidification focus to include investigations on the effects of climate change, forest harvesting and other forest ecosystem perturbations. The extensive scientific and support infrastructure allows for collection of a comprehensive data record essential for understanding long-term environmental trends. Data include atmospheric deposition, meteorology, stream hydrology and chemistry, soil, pore and ground water properties, understory and overstory vegetation, lake and outflow physical and chemical properties, and aquatic macroinvertebrate and fish community composition and abundance. These data have contributed to over 400 published research papers and graduate theses. The watershed has also figured prominently in many continent-wide comparisons advancing fundamental watershed theory. The knowledge gained at TLW has influenced pollutant emission and natural resource management policies provincially, nationally and internationally.     

Increasing discharge from the Mackenzie River system to the Arctic Ocean

The Mackenzie River, Canada's longest and largest river system, provides the greatest Western Hemisphere discharge to the Arctic Ocean. Recent reports of declining flows have prompted concern because (1) this influences Arctic Ocean salinity, stratification and polar ice; (2) a major tributary, the Peace River, has large hydroelectric projects, and further dams are proposed; and (3) the system includes the extensive and biodiverse Peace–Athabasca, Slave and Mackenzie deltas. To assess hydrological trends over the past century that could reflect climate change, we analysed historic patterns of river discharges. We expanded the data series by infilling for short gaps, calculating annual discharges from early summer‐only records (typical r² > 0.9), coordinating data from sequential hydrometric gauges (requiring r² > 0.8) and advancing the data to 2013. For trend detection, Pearson correlation provided similar outcomes to non‐parametric Kendall's τ and Spearman's ρ tests. There was no overall pattern for annual flows of the most southerly Athabasca River (1913–2013), while the adjacent, regulated Peace River displayed increasing flows (1916–2013, p < 0.05). These rivers combine to form the Slave River, which did not display an overall trend (1917–2013). The more northerly, free‐flowing Liard River is the largest tributary and displayed increasing annual flows (1944–2013, p < 0.01, ~3.5% per decade) because of increasing winter, spring, and summer flows, and annual maximum and minimum flows also increased. Following from the tributary contributions, the Mackenzie River flows gradually increased (Fort Simpson 1939–2013, p < 0.05, ~1.5% per decade), but the interannual patterns for the Liard and other rivers were correlated with the Pacific Decadal Oscillation, complicating the pattern. This conclusion of increasing river flows to the Arctic Ocean contrasts with some prior reports, based on shorter time series. The observed flow increase is consistent with increasing discharges of the large Eurasian Arctic drainages, suggesting a common northern response to climate change. Analyses of historic trends are strengthened with lengthening records, and with the Pacific Decadal Oscillation influence, we recommend century‐long records for northern rivers. Copyright © 2016 John Wiley & Sons, Ltd.     

Survival of lichens and bacteria exposed to outer space conditions - Results of the Lithopanspermia experiments

In the space experiments Lithopanspermia, experimental support was provided to the likelihood of the lithopanspermia concept that considers a viable transport of microorganisms between the terrestrial planets by means of meteorites. The rock colonising lichens Rhizocarpon geographicum and Xanthoria elegans, the vagrant lichen Aspicilia fruticulosa, and endolithic and endoevaporitic communities of cyanobacteria and bacteria with their natural rock substrate were exposed to space for 10 days onboard the Biopan facility of the European Space Agency (ESA). Biopan was closed during launch and re-entry. In addition, in the Stone facility, one sample of R. geographicum on its natural granitic substrate was attached at the outer surface of the re-entry capsule close to the stagnation point, only protected by a thin cover of glass textolite. Post-flight analysis, which included determination of the photosynthetic activity, LIVE/DEAD staining, and germination capacity of the ascospores, demonstrated that all three lichen were quite resistant to outer space conditions, which include the full spectrum of solar extraterrestrial electromagnetic radiation or selected wavelength ranges. This high resistance of the lichens to space appears to be due to their symbiotic nature and protection by their upper pigmented layer, the cortex. In contrast, the rock- or halite-inhabiting bacteria were severely damaged by the same exposure. After atmospheric re-entry, the granite of the Stone sample was transformed into a glassy, nearly homogenous material, with several friction striae. None of the lichen cells survived this re-entry process. The data suggest that lichens are suitable candidates for testing the concept of lithopanspermia, because they are extremely resistant to the harsh environment of outer space. The more critical event is the atmospheric re-entry after being captured by a planet. Experiments simulating the re-entry process of a microbe-carrying meteoroid did not show any survivors.     

Urban and rural groundwater use in Zhengzhou, China: challenges in joint management

Groundwater plays an important role in the total water supply of much of China, particularly in the north. It has contributed substantially to both agricultural growth and urban and industrial expansion. However, overexploitation and poor management have contributed to infamous groundwater depletion problems and less publicized groundwater quality deterioration. One of the key challenges for China will be how to make groundwater use sustainable while still meeting increased food needs as well as the industrial and domestic demands of a rapidly urbanizing society. Zhengzhou City, one of China’s test cities for building a “water saving society” highlights both the difficulties and potential solutions to northern China’s joint rural and urban groundwater challenges. Based on secondary data and a primary survey of groundwater management in the region, this report provides an overview of Zhengzhou’s groundwater development and use as well as the ongoing institutional and policy reform processes within the water sector. The results highlight how a deepening of ongoing reforms, which simultaneously consider groundwater as an integral rural and urban issue and a fundamental economic and social asset, may improve groundwater outcomes, not only in Zhengzhou but in China, as the country’s economy and demography continue to change.