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Britta Planer-Friedrich Corinne Lehr Jörg Matschullat Darrell Kirk Nordstrom 《Geochimica et cosmochimica acta》2006,70(10):2480-2491
Geothermal features in the Yellowstone National Park contain up to several milligram per liter of aqueous arsenic. Part of this arsenic is volatilized and released into the atmosphere. Total volatile arsenic concentrations of 0.5-200 mg/m3 at the surface of the hot springs were found to exceed the previously assumed nanogram per cubic meter range of background concentrations by orders of magnitude. Speciation of the volatile arsenic was performed using solid-phase micro-extraction fibers with analysis by GC-MS. The arsenic species most frequently identified in the samples is (CH3)2AsCl, followed by (CH3)3As, (CH3)2AsSCH3, and CH3AsCl2 in decreasing order of frequency. This report contains the first documented occurrence of chloro- and thioarsines in a natural environment. Toxicity, mobility, and degradation products are unknown. 相似文献
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Gerrit de Leeuw Lucinda Spokes Tim Jickells Carsten Ambelas Skjth Ole Hertel Elisabetta Vignati Susanne Tamm Michael Schulz Lise-Lotte Srensen Britta Pedersen Laura Klein K. Heinke Schlünzen 《Continental Shelf Research》2003,23(17-19):1743
The ANICE (Atmospheric Nitrogen Inputs into the Coastal Ecosystem) project addressed the atmospheric deposition of nitrogen to the North Sea, with emphasis on coastal effects. ANICE focused on quantifying the deposition of inorganic nitrogen compounds to the North Sea and the governing processes. An overview of the results from modelling and experimental efforts is presented. They serve to identify the role of the atmosphere as a source of biologically essential chemical species to the marine biota. Data from the Weybourne Atmospheric Observatory (UK) are used to evaluate the effect of short episodes with very high atmospheric nitrogen concentrations. One such episode resulted in an average deposition of 0.8 mmol N m−2 day−1, which has the potential to promote primary productivity of 5.3 mmol C m−2 day−1. This value is compared to long-term effects determined from model results. The total calculated atmospheric deposition to the North Sea in 1999 is 948 kg N km−1, i.e. 0.19 mmol N m−2 day−1 which has the potential to promote primary productivity of 1.2 mmol C m−2 day−1. Detailed results for August 1999 show strong gradients across the North Sea due to adjacent areas where emissions of NOx and NH3 are among the highest in Europe. The average atmospheric deposition to the southern part of the North Sea in August 1999 could potentially promote primary production of 2.0 mmol C m−2 day−1, i.e. 5.5% of the total production at this time of the year in this area of the North Sea. For the entire study area the atmospheric contribution to the primary production per m2 is about two-third of this value. Most of the deposition occurs during short periods with high atmospheric concentrations. This atmospheric nitrogen is almost entirely anthropogenic in origin and thus represents a human-induced perturbation of the ecosystem. 相似文献
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Britta Bielefeld 《GeoJournal》1997,42(2-3):329-336
In recent years, attention has increasingly been paid to the question of the stability of the earth's climate. It has been observed that changes in climate are usually related to changes in the earth's surface. On this question, Liedtke writes ‘A change in climate can lead to considerable landscape changes’ (Liedtke 1990, p. 38). There seems to be some form of interaction between climate and the condition of the earth's surface. If solar radiation is taken to be the primary energy source for the earth's climate, the question arises as to how insolation affects the character of the earth's surface, and vice versa, how does the character of the earth's surface affect the insolation which occurs? Reconstructions of the last great Pleistocene glaciation 18,000 years ago show that the form of the earth's surface at that time was considerably different to its present form. In view of the interaction mentioned above between climate and earth surface, does this suggest a difference between the earth's radiation budget 18,000 years ago and that of today? If, as is widely believed, the area of the earth's surface covered by ice 18,000 years ago was approximately three times the current area (Liedtke 1990, p. 42), this presumably would have had at least some influence on the earth's radiation budget. The ice-covered areas may have modified the radiation budget by means of their high reflexivity. In other words, an albedo-related loss of radiation may have occurred. The results of this investigations show, that the global radiation budget at 18,000 B.P was about 7- -10% less than that of today. 相似文献
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It is shown that there are MRV-related activities underway in South Africa, particularly focusing on measuring electricity consumption and monitoring GHG emissions. Yet currently many of these activities happen in parallel systems within multi-polar governance structures. A bottom-up perspective of MRV in South Africa, informed by interviews, workshops, desktop research, and stakeholder consultations, is provided and the systems, data, methodologies, and the institutional environment relevant to a South African MRV system are examined. The development of the local monitoring and evaluation system, and its relevance within the international MRV context, is also discussed. Some recommendations are made: most importantly, there is a need for a coherent approach to be developed, one that is coordinated by government and built on existing MRV systems. 相似文献
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Water quality in the Great Barrier Reef region: responses of mangrove, seagrass and macroalgal communities 总被引：1，自引：0，他引：1
Marine plants colonise several interconnected ecosystems in the Great Barrier Reef region including tidal wetlands, seagrass meadows and coral reefs. Water quality in some coastal areas is declining from human activities. Losses of mangrove and other tidal wetland communities are mostly the result of reclamation for coastal development of estuaries, e.g. for residential use, port infrastructure or marina development, and result in river bank destabilisation, deterioration of water clarity and loss of key coastal marine habitat. Coastal seagrass meadows are characterized by small ephemeral species. They are disturbed by increased turbidity after extreme flood events, but generally recover. There is no evidence of an overall seagrass decline or expansion. High nutrient and substrate availability and low grazing pressure on nearshore reefs have lead to changed benthic communities with high macroalgal abundance. Conservation and management of GBR macrophytes and their ecosystems is hampered by scarce ecological knowledge across macrophyte community types. 相似文献
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Tidal exchange between a freshwater tidal marsh and an impacted estuary: the Scheldt estuary, Belgium 总被引：1，自引：0，他引：1
Stefan Van Damme Dehairs Frank Tackx Micky Beauchard Olivier Struyf Eric Gribsholt Britta Van Cleemput Oswald Meire Patrick 《Estuarine, Coastal and Shelf Science》2009,85(2):197-207
Tidal marsh exchange studies are relatively simple tools to investigate the interaction between tidal marshes and estuaries. They have mostly been confined to only a few elements and to saltwater or brackish systems. This study presents mass-balance results of an integrated one year campaign in a freshwater tidal marsh along the Scheldt estuary (Belgium), covering oxygen, nutrients (N, P and Si), carbon, chlorophyll, suspended matter, chloride and sulfate. The role of seepage from the marsh was also investigated. A ranking between the parameters revealed that oxygenation was the strongest effect of the marsh on the estuarine water. Particulate parameters showed overall import. Export of dissolved silica (DSi) was more important than exchange of any other nutrient form. Export of DSi and import of total dissolved nitrogen (DIN) nevertheless contributed about equally to the increase of the Si:N ratio in the seepage water. The marsh had a counteracting effect on the long term trend of nutrient ratios in the estuary. 相似文献
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Britta Rennkamp 《Climate Policy》2019,19(6):756-770
This paper examines power relations, coalitions and conflicts that drive and hinder institutional change in South African climate policy. The analysis finds that the most contested climate policies are those that create distributional conflicts where powerful, non-poor actors will potentially experience real losses to their fossil fuel-based operations. This finding opposes the assumption of competing objectives between emissions and poverty reduction. Yet, actors use discourse that relates to potentially competing objectives between emissions reductions, jobs, poverty reduction and economic welfare.
The analysis relates to the broader questions on how to address public policy problems that affect the two objectives of mitigating climate change and simultaneously boosting socio-economic development. South Africa is a middle-income country that represents the challenge of accommodating simultaneous efforts for emissions and poverty reduction.
Institutional change has been constrained especially in the process towards establishing climate budgets and a carbon tax. The opposing coalitions have succeeded in delaying the implementation of these processes, as a result of unequal power relations. Institutional change in South African climate policy can be predominantly characterized as layering with elements of policy innovation. New policies build on existing regulations in all three cases of climate policy examined: the climate change response white paper, the carbon tax and the renewable energy programme. Unbalanced power relations between coalitions of support in government and civil society and opposition mainly from the affected industry result in very fragile institutional change.
Key policy insights
The South African government has managed to drive institutional change in climate policy significantly over the past 7 years.
Powerful coalitions of coal-related industries and their lobbies have constrained institutional change and managed to delay the implementation of carbon pricing measures.
A successfully managed renewable energy programme has started to transform a coal- and nuclear-powered electricity sector towards integrating sustainable energy technologies. The programme is vulnerable to intergovernmental opposition and requires management at the highest political levels.
Potential conflict with poverty reduction measures is not a major concern that actively hinders institutional change towards climate objectives. Predominantly non-poor actors frequently use poverty-related discourse to elevate their interests to issues of public concern.
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New biocide-free anti-fouling paints are toxic 总被引：1，自引：0，他引：1
A number of new anti-fouling paints claimed to be more friendly to the environment, have entered the market since prohibition of biocide containing paints have been enforced in many areas. Leakage waters from five new anti-fouling paints were tested for toxic effects to the macro algae Ceramium tenuicorne and Ceramium strictum and to the crustacean Nitocra spinipes. A banned copper and irgarol 1051 containing anti-fouling paint was used as reference. Five of the six paints tested were toxic to all or some of the organisms after two weeks of leakage with EC50 ranging from 0.08 to around 2% leakage water and LC50 ranging from 1.1% to 88%. The toxicity of leakage water from these paints was still high after 16 weeks. We conclude that these paints contain substances toxic to common organisms in the coastal Baltic ecosystem. A silicone based paint did not exhibit toxic effects to the two organisms. We recommend that biological tests should be used to identify the most harmful products before they are released on the market. 相似文献