7.  Tiwari, S., D. M. Chate, A. K. Srivastava, D. S. Bisht, and B. Padmanabhamurty: Assessments of PM1, PM2.5 and PM10 concentrations in Delhi at different mean cycles.

Daily, monthly, seasonal and annual moving means of PM1, PM2.5, and PM10 concentrations from August, 2007 to October, 2008 at Delhi (28º 35' N; 77º 12' E), the seventh populous megacity in the world are presented. PM1, PM2.5, and PM10 concentrations varied seasonally with atmospheric processes and the anthropogenic activities. PM10 decreases during monsoon by ~25–80 μg m-3 and PM1 and PM2.5 by ~10–15 μg m-3 from their pre-monsoon levels. Emissions from fireworks during Deepawali in the post-monsoon season increases PM1, PM2.5, and PM10 levels by 300, 350 and 400 μg m-3, respectively over their monsoon levels. Seasonal variation of mixing heights, temperatures, winds and rainfall, accounts for the inter-annual variability of PM1, PM2.5, and PM10. Accordingly, PM1, PM2.5, and PM10 components in winter are ~30–33%. PM10 in summer is higher by 8% to that of PM2.5 and by 9% to that of PM1. PM10 components in post-monsoon are lower by 5% to that of PM2.5 and by 7% to that of PM1. Also, PM1, PM2.5, and PM10 levels were higher during October, 2008 than those in 2007, but their levels were almost remain the same in August and September of 2007 and 2008. Moving means of PM1, PM2.5, and PM10 and their concentrations in different seasons are useful in policy making decisions thereupon aiming to improve the air quality in Delhi.

Keywords: running mean cycles, air-quality, residence time, particulate matter, wet removal

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8.  Andreiæ, ®., D. Andreiæ and K. Pavliæ: Near infrared light pollution measurements in Croatian sites.

We investigate the light pollution (LP) in the near-infrared (NIR) part of the electromagnetic spectrum (700–1000 nm) for sites at low altitude, as typical for small observatories in this region. Our measurements show that considerable light pollution exists in the NIR. The increase of night sky brightness towards the horizon is often slightly slower in the NIR than in the visible. In cases when LP is mostly produced by high-pressure sodium lamps, the NIR part of light pollution is dominated by two close sodium spectral lines (818.3 and 819.5 nm) that can easily be filtered out with a dedicated filter. This can, however, change as sodium lamps are gradually replaced by metal-halide lamps whose spectra are complex, showing many lines over the whole visible/infrared range. If in the future a change to LED light sources happens, LP in the NIR could be reduced drastically. Last, but not least, the low altitude of observing sites, together with climate characteristics of the region, result in a lot more humidity and aerosols in the atmosphere, compared to a typical mountaintop observatory site. This, combined with proximity of the polluting sources to the observing sites, results in enhancing the LP, compared to the clear, dry atmospheric conditions of a mountaintop observatory.

Keywords: light pollution, infrared: general

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9.  Taiwo, A. M.: Source identification and apportionment of pollution sources to groundwater quality in major cities in Southwest, Nigeria.

Groundwater in form of hand-dug wells and boreholes serves as the main source of drinking water to the people of south-western Nigeria. Contamination of this resource has been linked to many ambiguous pollution sources. The aim of this paper is to identify and apportion sources of pollution to groundwater in five major cities in south-western Nigeria using Principal Components Analysis (PCA). Studies on physico-chemical parameters of groundwater from Abeokuta, Ifo, Sango, Ibadan and Lagos were adopted from published literatures, and evaluated using a SPSS statistical package. PCA revealed factor ranges between four and eight. Sources identified were bedrock weathering/sea water, nutrient, solids, urban/traffic runoff, industry, hardness, faecal pollution, soil leaching, nutrient, salt-water intrusion and leachate.

Keywords: groundwater, factor, PCA, pollution, loading, southwest Nigeria

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10.  Feumoe, A. N. S., T. Ndougsa-Mbarga, E. Manguelle-Dicoum and J. D. Fairhead: Delineation of tectonic lineaments using aeromagnetic data for the south-east Cameroon area.

The subsurface structures in a part of the Congo Craton in south-eastern Cameroon, between the latitudes 2° to 3° N and longitudes 13° to 15° E, has been estimated by the interpretation of aeromagnetic data. Magnetic survey is used to delineate magnetic lineaments, analyze its relationship to the tectonic fabric and to estimate the depth of perturbing body source, probably granitic intrusion along one profile selected on the total magnetic intensity reduced to the equator (TMI-RTE) map by means of forward modelling and inversion constrained by surface geology and results from Euler deconvolution analysis method. Determination of the magnitude maxima of the first vertical derivative (FVD) of the residual field reduce to the equator allowed a map to be produced showing various aeromagnetic lineaments interpreted as the fault system of the studied area. Particularly, looking at the center of the structural map, we find that these structures are associated to long-wavelength anomalies, suggesting that its should be connected with large-scale structural deformation. The pseudo-gravity map shows the extension of the tillitic formations on the geological map. Our results confirms the morphological difference and the tectonical subdivision into two tectonic sectors corresponding to the Congo Craton in the south, Pan-African in the north and also helped identify the tectonic boundary separating them at depth.

Keywords: Magnetic anomaly, reduction-to-the equator, first vertical derivative, pseudo-gravity and Euler deconvolution

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