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Atmospheric dust affects climate, biogeochemistry, and human health, with total emissions estimated at 1,500 to 3,000 Tg yr−1. The Bodele Depression, Chad (17˚N, 18˚E) in the Saharan Desert is the largest single point source of dust in the world, and dust from the Bodele, and the Sahara in general, has been tracked across much of the world, including to the Caribbean and the Americas. Although it has been linked to negative health effects in sink regions, few have worked to understand its local health effects in Africa. The lack of ground-based stations in North Africa and the inaccessibility of much of the region call for a remote technique to track dust concentration and composition as it moves across Africa. Such a method would provide a more detailed understanding of dust dynamics in North Africa and reveal the potential health effects of dust in the region. Here, we combine aerosol optical thickness measurements from MODIS and dust concentrations from the DREAM model with hyperspectral imagery from t...

CALMET/CALPUFF modeling system is frequently used in the study of atmospheric processes and pollution, and several validation tests were performed until now; nevertheless, most of them were based on experiments with a large compilation of surface and aloft meteorological measurements, rarely available. At the same time, the use of a large operational smokestack as tracer/pollutant source is not usual. In this work, first CALMET meteorological diagnostic model is nested to WRF meteorological prognostic model simulations (3x3 km2 horizontal resolution) over a complex terrain and coastal domain at NW Spain, covering 100x100 km2, with a coal-fired power plant emitting SO2. Simulations were performed during three different periods when SO2 hourly glc peaks were observed. NCEP reanalysis were applied as initial and boundary conditions. Yong Sei University-Pleim-Chang (YSU) PBL scheme was selected in the WRF model to provide the best input to three different CALMET horizontal resolutions, 1x1 km2, 0.5x0.5 km2, and 0.2x0.2 km2. The best results, very similar between them, were achieved using the last two resolutions; therefore, the 0.5x0.5 km2 resolution was selected to test different CALMET meteorological inputs, using several combinations of WRF outputs and/or surface and upper-air measurements available in the simulation domain. With respect to meteorological aloft models output, CALMET PBL depth estimations are very similar to PBL depth estimations using upper-air measurements (rawinsondes), and significantly better than WRF PBL depth results. Regarding surface models surface output, the available meteorological sites were divided in two groups, one to provide meteorological input to CALMET (when applied), and another to models validation. Comparing WRF and CALMET outputs against surface measurements (from sites for models validation) the lowest RMSE was achieved using as CALMET input dataset WRF output combined with surface measurements (from sites for CALMET model input). Following, CALPUFF model was applied to simulate the local atmospheric diffusion of SO2 (as an inert tracer) from a large power plant smokestack (with four parallel independent liners), considering two different stack configurations (one single point source as a summa of four liners vs. one point source per liner) and two different CALMET meteorological simulations (using as input dataset only the WRF model output vs. only surface and upper-air meteorological measurements). Comparison of those CALPUFF simulations results against the hourly average ground level concentration (glc) measurements shows that the best model performance was obtained by using only WRF model output as CALMET input; also, better glc results are obtained considering one point source per liner in CALPUFF simulations.

We report results of a preliminary study of particulate and dissolved organic carbon transport in the Ayeyarwady and Thanlwin Rivers of Myanmar, based on 52 suspended sediment samples and 9 water samples collected during conditions of low and high flow in 2005 and 2006. The Ayeyarwady transports 2.2–4.3 MtC/yr as POC with a weighted average δ 13 C value of - 24.8 ‰ , while the Thanlwin transports an additional 2.4–3.4 MtC/yr with a δ 13 C value of - 25.3 ‰ . In addition, the Ayeyarwady transports ∼ 0.9 Mt / yr , and the Thanlwin ∼ 0.23 Mt / yr , of DOC with a δ 13 C value of - 26.2 ‰ and - 27.1 ‰ , respectively. The Ayeyarwady and Thanlwin catchments adjoin each other, debouching into the Indian Ocean over a length scale similar to the deltas of the Ganges–Brahmaputra or the Amazon. Therefore, the Ayeyarwady and Thanlwin rivers should be considered a single point source contributing to the global ocean. This combined river system transports 5.7–8.8 MtC/yr of organic carbon, suggesting that it may be the second largest point source of organic carbon to the global ocean after the Amazon. The implied organic carbon yield from the catchments is 8.4–12.9 t/km2/yr, which is clearly amongst the highest in the world among rivers of similarly large size. The high organic carbon yields are likely to be the result of (i) a strongly monsoonal climate, (ii) the large area of highly productive forest present on steep slopes in a region of active tectonism, and (iii) the comparatively small area of floodplain in the catchments.

The transport of contaminated sediment out of Lake Erie is an important process controlling the fate of potentially toxic organic compounds in the lower Great Lakes. This transport was investigated by electron capture gas chromatographic mass spectrometry analysis of 2,4-di-tert-pentylphenol (24DP) and 2-chloro-4,6-di-tert-pentylphenol (24DP6Cl) derivatized with pentafluorobenzyl bromide (PFBBr) to give PFB ether derivatives. 24DP and 24DP6Cl are unusual sediment-bound pollutants originating from a single point source on the Trenton Channel of the Detroit River. The concentrations of these compounds were determined in suspended solids collected between 1980 and 1993 in the Niagara River

The volcano Askja in east-central Iceland erupted several times between 1920 and 1930, following a very large caldera-forming eruption in 1875. The last eruption occurred in 1961. Measurements of the vertical component of ground deformation in Askja were commenced in 1966 and made once each year, 1966 to 1972 and 1983 to 1987. Distance measurements with a geodimeter were first made in 1982. The measurements have shown alternating uplift and subsidence of the central part of the Askja caldera. Two periods of uplift and three periods of subsidence have been identified during the 21 years of observations. Observed vertical displacements agree fairly well with a single point source model at a depth of 1.5–3.5 km below the surface, near the center of the Askja caldera. Deviation from a single point source model can be explained by a secondary source of subsidence beneath the site of the 1961 eruption. This secondary source has been diminishing in intensity and appears to have been exhausted by 1983–1987. Askja has been subsiding at a rate of 6–10 cm per year during the period 1983–1987, but in 1970–1972 rapid inflation was observed possibly as much as 20 cm per year. The period of no levelings, 1972 to 1983, is characterized by deflation, but at a slower average rate than observed in 1983–1987. This suggests continuation of the 1970–1972 inflation into 1973 or 1974.

Travel time data, from widely recorded nuclear detonations in the Eniwetok and Bikini atolls of the central Pacific, have been compiled and are presented. Although a number of stations recorded ten or more events from each atoll, the resulting data may be considered as from a single point source, precisely known in time and place. Composite P-wave travel times are presented in a graphical form and, in the distance range from 3 to 102 degrees, are represented as eight near straight-line segments. P-wave speeds in the top of the mantle average about 8.2 km/sec to distances beyond 17 degrees, and a sharp discontinuity at 19.5 degrees is indicated. There is no evidence for or against a low-speed layer in the upper mantle nor for a regional shadow zone. A mantle model consisting of a number of discrete spherical shells has been constructed. A core depth of 2,870 km, 30 km short of the accepted value, is calculated from PcP arrival times at Matsushiro and College, which are 2.5 and 3.5 sec. earlier than are indicated in the Jeffreys-Bullen tables.