Xem 1-5 trên 5 kết quả Current soil carbon
  • Beyond TMT, we find no systematic increase in the importance of industry effects. Instead, we observe that the ratio of industry to country effects follows a U-shape pattern from the mid-1980s to the late-1990s, a cyclical pattern whereby global industry effects become temporarily more important in relative and absolute terms around periods of stock market distress, such as October 1987 and March 2000. We view this cyclical pattern as further evidence that the recent increase in industry effects is temporary....

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  • Natural groundwater quality changes start in the soil, where infiltrating rainfall dissolves carbon dioxide from biological activity in the soil to produce weak carbonic acid that may assist removal of soluble minerals from the underlying rocks, e.g. calcite cements. At the same time, soil organisms consume some of the oxygen that was dissolved in the rainfall. In temperate and humid climates with significant recharge, groundwater moves relatively quickly through the aquifer.

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  • Concurrent treatment of source area saturated and unsaturated zones usually requires the integration of chemical oxidation with other remedial technologies that target unsaturated zone contamination (e.g., soil vapor extraction). Frequently, soil vapor extraction, which is used to treat the unsaturated zone, is included as a component of chemical oxidation remedial solutions even if there is no specific need to treat unsaturated soils in the source area.

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  • Care should be taken in choosing preservatives. For example, Method 5035 notes that, “Soil samples that contain carbonate minerals (either from natural sources or applied as an amendment) may effervesce upon contact with the acidic preservative solution in the low concentration sample vial.” Therefore, calcareous soils that effervesce on contact with the preservative solution, which is intended for low-level samples, should be preserved using an alternative technique.

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  • The stocks of greenhouse gases in the atmosphere (including carbon dioxide, methane, nitrous oxides and a number of gases that arise from industrial processes) are rising, as a result of human activity. The sources are summarised in Figure 1 below. The current level or stock of greenhouse gases in the atmosphere is equivalent to around 430 parts per million (ppm) CO2 1 , compared with only 280ppm before the Industrial Revolution. These concentrations have already caused the world to warm by more than half a degree Celsius and will lead to at least a further half...

    pdf74p trinhcaidat 19-04-2013 40 2   Download

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