Solution to the Stokes Boundary-Value Problem on an Ellipsoid of Revolution

We have constructed Green's function to Stokes's boundary-value problem with the gravity data distributed over an ellipsoid of revolution. We show that the problem has a unique solution provided that the first eccentricity e₀ of the ellipsoid of revolution is less than 0·65041. The ellipsoidal Stokes function describing the effect of ellipticity of the boundary is expressed in the E-approximation as a finite sum of elementary functions which describe analytically the behaviour of the ellipsoidal Stokes function at the singular point = 0. We prove that the degree of singularity of the ellipsoidal Stokes function in the vicinity of its singular point is the same as that of the spherical Stokes function.     

Response of vegetation pattern to different landform and water-table depth in Hailiutu River basin,Northwestern China

The spatial distribution of vegetation pattern and vegetation cover fraction (VCF) was quantified with remote sensing data in the Hailiutu River basin, a semiarid area in North China. The moderate resolution imaging spectroradiometer normalized different vegetation index (NDVI) values for 4 years from 2008 to 2011 and field observation data were used to assess the impact of climate factors, landform and depth to water table on vegetation distribution at large scale. In the VCF map, 74 % of the study area is covered with low and low–medium density vegetation, 24 % of the catchment is occupied by medium–high and high-density vegetation, and 2 % of area is bare soil. The relationship between NDVI and climate factors indicated that NDVI is correlated with relative humidity and precipitation. In the river catchment, NDVI increases gradually from landform of sand dune, eolian sand soil to river valley; 92.4 % of low NDVI from 0.15 to 0.3 is mostly distributed in sand dunes and the vegetation type is shrubs. Crops, shrubs and some dry willows dominate in eolian sand soil and 82.5 % of the NDVI varies between 0.2 and 0.35. In the river valley, 70.4 % of NDVI ranges between 0.25 and 0.4, and grass, dry willow and some crops are the main plants. Shrubs development of Korshinsk peashrub and Salix psammophila are dependent on groundwater by analyzing NDVI response to groundwater depth. However, NDVI of Artemisia desertorum had little sensitivity to groundwater.     

Partitioning of dioxins (PCDDs/Fs) in ambient air at urban residential locations

In this work, 17-polychlorinated dibenzo-p-dioxin/furan (PCDD/Fs) isomers were measured in ambient air at four urban sites in Seoul, Korea (from February to June 2009). The concentrations of their summed values (ΣPCDD/Fs) across all four sites ranged from 1,947 (271 WHO₀₅ TEQ) (Jong Ro) to 2,600 (349 WHO₀₅ TEQ) fg/m³ (Yang Jae) with a mean of 2,125 (± 317) fg/m³ (292 WHO₀₅ TEQ fg/m³). The sum values for the two isomer groups of ΣPCDD and ΣPCDF were 527 (30 WHO₀₅ TEQ) and 1,598 (263 WHO₀₅ TEQ) fg/m³, respectively. The concentration profile of individual species was dominated by the 2,3,4,7,8-PeCDF isomer, which contributed approximately 36 % of the ΣPCDD/Fs value. The observed temporal trends in PCDD/F concentrations were characterized by relative enhancement in the winter and spring. The relative contribution of different sources, when assessed by principal component analysis, is explained by the dominance of vehicular emissions along with coal (or gas) burning as the key source of ambient PCDD/Fs in the residential areas studied.     

Sandstone alterations triggered by fire-related temperatures

The aim of the study was to identify and describe changes in two different sandstone types when undergoing different environmental and extreme temperature regimes to assess the possibility of finding insolation weathering and how these sandstones would behave during and after a fire. The first step was the simulation in the laboratory of temperature regimes up to 60 °C which would correspond to extreme events that could be found in insolation cycles even in Central Europe and the second one was the temperature above 200 °C simulating in laboratory conditions the thermal regime of a potential fire situation at temperatures up to 200, 400, 600 and 800 °C. Heating the samples above 400 °C led to gradual changes in mineral composition, colour, surface roughness and physical properties reaching, eventually, total rock breakdown through spalling and granular disaggregation. The different behaviour of sandstones exposed to high temperatures is mainly caused by their different mineral composition with various ratios of minerals that are more or less chemically stable at high temperatures as well as by the differences in the porosity.     

Influences of mulching durations on soil erosion and nutrient losses in a peanut (Arachis hypogaea)-cultivated land

Plastic film mulching is widely employed to improve crop yields. Mulching for the entire crop growth period is a widespread practice. However, a shorter plastic film mulching duration is suggested for obtaining larger grain yield recently. To quantify the effects of plastic film mulching durations on soil erosion and nutrient losses, a three-treatment experiment with three replicates was constructed in field. The designed treatments were control (M0, non-mulched treatment), mulching from sowing to the end of the peanut pod-setting stage (M1) and pod-filling stage (M2). Plastic film mulching significantly increased the mean runoff and sediment yield. With film mulching, the mean runoff and soil losses among M1 and M2 treatments had no significant difference, and significantly larger than that in M0 treatment. After mulching removing, there were no significant differences between the mean runoff and soil losses of M0 and M1 treatments. Compared with the M2 treatment, the M0 treatment had significantly reduced mean runoff and soil losses of all the events. Non-mulching increased the total nitrogen (TN) and total phosphorus (TP) losses. The M0 treatment had the highest TN (23.0 mg m^?2) and TP (3.02 mg m^?2) losses in the three treatments. The M2 treatment significantly reduced the TN and TP losses. In conclusion, mulching from sowing to the end of pod-setting stage was suggested as the appropriate choice for the largest yield and less soil erosion. But, some soil conservation measurements should be taken in furrow areas to effectively reduce soil erosion, under the condition of film mulching.     

Health risk of heavy metals from vegetables irrigated with sewage water in peri-urban of Dera Ismail Khan,Pakistan

Health risks of heavy metals in vegetables irrigated with sewage water were investigated in the present study. The findings indicated a massive accumulation of heavy metals in soil and vegetables collected from Dera Ismail khan, Pakistan. The concentration levels of heavy metal in vegetables grown on soil irrigated with untreated sewage water were significantly higher at (P ≤ 0.001) than in vegetables grown on fresh-water-irrigated soil and proceeded the recommended limits of World health organization. Moreover, the findings also indicated that the adults and children consuming such vegetables ingested a large proportion of the selected toxic metals. Health risk index was greater than one for Pb and Cd in all the selected vegetables and was greater than one for Ni in three vegetables like Spinacia oleracea, Benincasa fistulosa and Lactuca sativa. Health risk assessment would be a useful tool for information regarding any threats of heavy metals contamination in vegetables.