Sorption and transport of radionuclides by tumbleweeds from two plastic-lined radioactive waste ponds

Previous research has examined the uptake of radionuclides by tumbleweeds growing in contaminated soils, but none has heretofore examined the sorption of radionuclides to tumbleweeds blowing into radioactively contaminated water. Three tumbleweed species; Russian thistle (Salsola kali), Jim Hill mustard (Sisymbrium altissimum) and summer cypress (Kochia scoparia) blow in, and out of, two plastic-lined radioactive wastewater ponds, constructed in 1993 on the US Department of Energy's Idaho National Engineering and Environmental Laboratory in southeast Idaho. This research quantified radionuclide sorption to tumbleweeds, tumbleweed movement from the ponds, and determined radionuclide transport from the ponds. Average plant/water concentration factors associated with tumbleweeds taken from the ponds ranged from 5 for 152Eu to over 9000 for 54Mn. Based on changes in tumbleweed numbers and average concentrations associated with them, 66.2 MBq were estimated to have been transported from the ponds via tumbleweeds between 18 October 1994 and 8 November 1996. This amounts to about 0.01% of the non-tritium and 0.0002% of the tritium activity released to the ponds through 8 November 1996. A power function best described the radionuclide buildup curve for tumbleweeds submerged in the ponds. Visually marked tumbleweeds traveled from the ponds in the predominant wind direction a maximum of 737 m. Management practices which may reduce the number of tumbleweeds blowing both into and out of contaminated ponds are discussed.     

Impacts of land use,restoration, and climate change on tropical peat carbon stocks in the twenty-first century: implications for climate mitigation

The climate mitigation potential of tropical peatlands has gained increased attention as Southeast Asian peatlands are being deforested, drained and burned at very high rates, causing globally significant carbon dioxide (CO₂) emissions to the atmosphere. We used a process-based dynamic tropical peatland model to explore peat carbon (C) dynamics of several management scenarios within the context of simulated twenty-first century climate change. Simulations of all scenarios with land use, including restoration, indicated net C losses over the twenty-first century ranging from 10 to 100 % of pre-disturbance values. Fire can be the dominant C-loss pathway, particularly in the drier climate scenario we tested. Simulated 100 years of oil palm (Elaeis guineensis) cultivation with an initial prescribed burn resulted in 2400–3000 Mg CO₂?ha^?1 total emissions. Simulated restoration following one 25-year oil palm rotation reduced total emissions to 440–1200 Mg CO₂?ha^?1, depending on climate. These results suggest that even under a very optimistic scenario of hydrological and forest restoration and the wettest climate regime, only about one third of the peat C lost to the atmosphere from 25 years of oil palm cultivation can be recovered in the following 75 years if the site is restored. Emissions from a simulated land degradation scenario were most sensitive to climate, with total emissions ranging from 230 to 10,600 Mg CO₂?ha^?1 over 100 years for the wettest and driest dry season scenarios, respectively. The large difference was driven by increased fire probability. Therefore, peat fire suppression is an effective management tool to maintain tropical peatland C stocks in the near term and should be a high priority for climate mitigation efforts. In total, we estimate emissions from current cleared peatlands and peatlands converted to oil palm in Southeast Asia to be 8.7 Gt CO₂ over 100 years with a moderate twenty-first century climate. These emissions could be minimized by effective fire suppression and hydrological restoration.     

Habitat Use and Movements of Two Ecotypes of Translocated Caribou in Idaho and British Columbia

Two woodland caribou ( Rangifer tarandus caribou ) ecotypes, mountain and northern, were translocated to the southern Selkirk Mountains in northern Idaho (U.S.A.) to augment a remnant subpopulation. The translocation resulted in an additional subpopulation that used the general area of the release site. The mountain ecotype stock exhibited patterns of movement and habitat use similar to those of the resident subpopulation. The northern ecotype stock exhibited more variable habitat use, especially in the first year after translocation. Dispersal of the northern stock was not as extensive as that of the mountain stock. Fourteen of 22 caribou from the northern stock and 6 of 18 caribou from the mountain stock died during the 3-year period after the release. Our results suggest that when donor subpopulations must be used that do not closely compare with resident subpopulations extinct or extant, larger numbers of individuals may be needed to establish a self-sustaining population.     

Sustainability： A view from the wind-eroded field

This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeo- aeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground （even when they are attached to dust-sized particles）, and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustalnabillty of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas （like China, the Sahel and Norflawestern Europe） generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth （so that wind erosion may even improve the soil）. Finally some remarks are made about environmental change in relation to sustainability.     

Environmental Impact Assessment Under the National Environmental Policy Act and the Protocol on Environmental Protection to the Antarctic Treaty

US government actions undertaken in Antarctica are subject to the requirements of both the Protocol and the US National Environmental Policy Act (NEPA). There are differences in the scope and intent of the Protocol and NEPA; however, both require environmental impact assessment (EIA) as part of the planning process for proposed actions that have the potential for environmental impacts. In this paper we describe the two instruments and highlight key similarities and differences with particular attention to EIA. Through this comparison of the EIA requirements of NEPA and the Protocol, we show how the requirements of each can be used in concert to provide enhanced environmental protection for the antarctic environment. NEPA applies only to actions of the US government; therefore, because NEPA includes certain desirable attributes that have been refined and clarified through numerous court cases, and because the Protocol is just entering implementation internationally, some recommendations are made for strengthening the procedural requirements of the Protocol for activities undertaken by all Parties in Antarctica. The Protocol gives clear and strong guidance for protection of specific, valued antarctic environmental resources including intrinsic wilderness and aesthetic values, and the value of Antarctica as an area for scientific research. That guidance requires a higher standard of environmental protection for Antarctica than is required in other parts of the world. This paper shows that taken together NEPA and the Protocol call for closer examination of proposed actions and a more rigorous consideration of environmental impacts than either would alone. Three areas are identified where the EIA provisions of the Protocol could be strengthened to improve its effectiveness. First, the thresholds defined by the Protocol need to be clarified. Specifically, the meanings of the terms “minor” and “transitory” are not clear in the context of the Protocol. The use of “or” in the phrase “minor or transitory” further confuses the meaning. Second, cumulative impact assessment is called for by the Protocol but is not defined. A clear definition could reduce the chance that cumulative impacts would be given inadequate consideration. Finally, the public has limited opportunities to comment on or influence the preparation of initial or comprehensive environmental evaluations. Experience has shown that public input to environmental documents has a considerable influence on agency decision making and the quality of EIA that agencies perform.     

Conservation Applications of Astronaut Photographs of Earth: Tidal-Flat Loss ( Japan), Elephant Effects on Vegetation (Botswana), and Seagrass and Mangrove Monitoring (Australia)

Abstract: National Aeronautics and Space Administration ( NASA) photographs taken by astronauts from low Earth orbit can provide information relevant to conservation biology. This data source is now more accessible because of improvements in digitizing technology, Internet file transfer, and availability of image processing software. We present three examples of conservation-related projects that benefited from the use of astronaut photographs. First, NASA scientists requested that astronauts photograph the area of the controversial Isahaya Bay reclamation project in Japan. Japanese researchers used photographs from before and after the reclamation as a tool for communication with the public about the effects of tidal-flat loss. The newly acquired images and the availability of high-resolution digital images from NASA archives provided timely public information on the observed changes. Second, we digitally classified and analyzed a Space Shuttle photograph of Chobe National Park in Botswana to identify the locations of woodlands affected by elephants. Field validation later confirmed that areas identified on the image showed evidence of elephant damage. Third, we used a summary map from intensive field surveys of seagrasses in Shoalwater Bay, Australia, as reference data for a supervised classification of a digitized photograph taken from orbit. The classification distinguished seagrasses, sediments, and mangroves with accuracy approximating that in studies using other satellite remote-sensing data. Astronaut photographs are in the public domain, and the database of nearly 400,000 photographs from the late 1960s to the present is available at a single searchable location on the Internet (  http://eol.jsc.nasa.gov/sseop ). These photographs can be used by conservation biologists as a source of general information about the landscape and for quantitative mapping.