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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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Jacob Garty Lior Weissman Tal Levin Rachel Garty-Spitz Haya Lehr 《Journal of Atmospheric Chemistry》2004,49(1-3):251-266
To assess the impact of UV-B radiation combined with NaHSO3 in solution under laboratory conditions, we compared the amounts of stress-ethylene produced by two lichen species of the same genus. Ramalina lacera, an epiphytic Mediterranean lichen, was found to be rather sensitive to UV-B combined with NaHSO3, relative to the epilithic desert lichen R. maciformis. The impact of high temperatures with FeCl2 in solution, measured by amounts of stress ethylene accentuated the adaptability of R. maciformis to desert conditions, whereas R. lacera appeared to be rather sensitive to extreme temperatures especially in the case of chemical contamination. The adaptability of R. maciformis to UV-B appears to be related to the photoprotective capabilities of lichen substances. 相似文献
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Xiu Luo Hiroshi Haya Tomoaki Inaba Tomoki Shiotani 《Soil Dynamics and Earthquake Engineering》2006,26(12):1101-1110
One difficult task for the seismic diagnosis of existing structures is how to nondestructively evaluate the damage degree of invisible substructures, such as embedded foundations. To diagnose substructures efficiently, a method for nondestructive inspection is developed by applying acoustic emission (AE) technique. As a newly proposed method, characteristics of secondary AE induced by train operations were investigated, and experiments using model piles and in-situ AE monitoring of in-service railway bridges conducted under railroad traffic, from which it was demonstrated that the proposed method is practicable enough to detect invisible defects in structures. A new index, known as RTRI (ratio of Repeated Train load at the onset of AE activity to Relative maximum load for Inspection period) is proposed for structural damage qualification based on the results of in-situ AE monitoring. 相似文献
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A computer simulation program of oil spills in the Arabian Gulf, GULFSLIK II, is developed and applied to two offshore fields. The results of the simulation are examined to ascertain the risks to the neighboring coastal areas. 相似文献
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As elsewhere in Indonesia, local inhabitants in the Pangkajene and Kepulauan (PANGKEP) Regency, Spermonde Archipelago area and along the south-west coast of Sulawesi traditionally regard the coral reefs as their livelihood source. Since human activities as well as natural disturbances pose major threats to the coral reefs, these livelihoods may also be at risk. Currently, no comprehensive information on the status and condition of coral reefs in this area is available for this resource management. We determined the changes of coral reef habitat over a period of 20 years from 1994 to 2014 using a satellite Landsat multi-temporal image substantiated with in situ measurement data collected in 2014. The spectral value of coral reefs was extracted from multi-temporal Landsat imagery data, while the diffuse attenuation coefficient of water was obtained by using statistical analysis between the ratio of live coral cover and the spectral value of the visible bands. By using the unsupervised classification integrated with the data ground truth, it is stated that there has been a decline in live coral cover over a period of 20 years from 7716 ha in 1994 to 4236 ha in 2014, with a degradation rate of 174 ha/year. Based on the results, the ratio of the coral cover in the coral reef transects varied from the average of 24% for live corals to 96% for coral rubbles, implying the degraded status of coral reefs in the study area. 相似文献
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This study was undertaken to develop an approach for modelling changes of sediment chemistry related to the accumulation of aquaculture waste. Metal composition of sediment Al, Cu, Fe, Li, Mn, and Zn; organic carbon and < 63 microm particles were used to determine the extent of detectable effects around the cage. This study showed marked differences in the sediment chemistry between aquaculture sites and the natural background: (1) negative correlations between sediment Cu and Zn with Al, (2) poor correlations between metals and Li, and (3) concentrations of Fe and Mn decreased with increased accumulation of organic carbon. There is a trend among normalised metals, organic carbon and particles related to normal, hypoxic and anoxic sediment conditions. The trends are useful for detecting and assessing the cumulative effects from aquaculture wastes to the marine environment. Lithium is less interactive with other metals in aquaculture sediments compared with the natural background sediments. Principal components analysis (PCA) was carried out on the metals, organic carbon, and particles to cluster the similarities of the variables so as to establish the predicted or adjusted environmental monitoring program (EMP) ratings. This approach, using the adjusted EMP rating based on sediment chemistry, yields a regression model with R2 = 0.945 compared to R2= 0.653 for the regression model using unadjusted EMP for assessing the environmental conditions. 相似文献
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