The spatio-temporal variations of soil gas in the seismic fault zone produced by the 12 May 2008 Wenchuan Ms 8.0 earthquake were investigated based on the field measurements of soil gas concentrations after the main shock. Concentrations of He, H2, CO2, CH4, O2, N2, Rn, and Hg in soil gas were measured in the field at eight short profiles across the seismic rupture zone in June and December 2008 and July 2009. Soil-gas concentrations of more than 800 sampling sites were obtained. The data showed that the magnitudes of the He and H2 anomalies of three surveys declined significantly with decreasing strength of the aftershocks with time. The maximum concentrations of He and H2 (40 and 279.4 ppm, respectively) were found in three replicates at the south part of the rupture zone close to the epicenter. The spatio-temporal variations of CO2, Rn, and Hg concentrations differed obviously between the north and south parts of the fault zone. The maximum He and H2 concentrations in Jun 2008 occurred near the parts of the rupture zone where vertical displacements were larger. The anomalies of He, H2, CO2, Rn, and Hg concentrations could be related to the variation in the regional stress field and the aftershock activity. 相似文献
The study area is located in Three Gorges Reservoir region, China. Over 200 landslides have been monitored over a number of
years with their behavior being compared to the effective rainfall database for the study area. Analysis of the available
data indicates that the occurrences of landslides in this region are controlled by rainfall, whose intensity and rainfall
processes are the most important dynamic factors in determining the stability of slopes. Therefore, the relationship between
rainfall and the movement of typical landslides has been specifically analyzed for the Xintan landslides and the large Huangya
landslide by using the loading/unloading response ratio parameter of rainfall. The result of this study indicates that the
mutation of the loading/unloading response ratio of rainfall of the Xintan landslide and the large Huangya landslide in the
Three Gorges Reservoir region, China occurred just before their destabilization, which shows that the loading/unloading response
ratio of rainfall and its changing feature can be taken as a precursor for the landslides induced by rainfall. 相似文献
The results of a first systematic study of spatial distribution of different elements in surface soil over of the Kavadarci
region, Republic of Macedonia, known for its nickel industrial activity are reported. The investigated region (360 km2) is covered by a sampling grid of 2 × 2 km2; whereas the sampling grid of 1 × 1 km2 was applied in the urban zone and around the ferronickel smelter plant (117 km2). In total 344 soil samples from 172 locations were collected. At each sampling point soil samples were collected at two
depths, topsoil (0–5 cm) and bottom soil (20–30 cm). Inductively coupled plasma-mass spectrometry (ICP-MS) was applied for
the determination of 36 elements (Ag, Al, As, Au, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, K, La, Mn, Na, Mg, Mo, Ni, P,
Pb, S, Sb, Sc, Se, Sr, Th, Tl, Ti, U, V, W and Zn). Data analysis and construction of maps were performed using the Paradox
(ver. 9), Statistica (ver. 6.1), AutoDesk Map (ver. 2008) and Surfer (ver. 8.09) software. Four geogenic and three anthropogenic
geochemical associations were established. Within the research, natural and anthropogenic enrichment with heavy metals was
determined. Principally, the natural enrichment is related especially to Ni. Pollution by As, Cd, Co, Cr, Cu, Hg, Mo, Pb and
Zn is basically insignificant. 相似文献
The dynamics of desertification in the Horqin Sandy Land between 2000 and 2005 were analyzed using Landsat TM/ETM images and
the data-processing function of geographical information software. The results showed that the extent of desertified land
decreased at a rate of slightly more than 0.1 km2 year−1, from 22,423.1 km2 in 2000 to 22,422.4 km2 in 2005, indicating that desertification has been controlled in this area and that desert areas may be approaching a steady
state. The dynamics of desertification differed among land types. Desertification decreased most obviously in areas of previous
desert land. The area in which desertification was ameliorated was higher than the area that underwent further degradation,
but non-desertified land (113.3 km2) deteriorated at a rate of 22.7 km2 year−1 during this period. This significant change requires careful attention by managers in the study area. 相似文献
Devonian strata in the Guizhong region, Guangxi, China consist mainly of marine deposition carbonates (limestones and dolomites) as well as restricted clastic rocks. The strata thickness is measured as 2041m and classified into 14 formations. An integrated field geological, petrographic, sedimentological, palaeobiological, and geochemical study of these strata reveals that the depositional paleoenvironments were carbonate tidal flat, restricted platform, open platform, shelf, platform margin slop, and algal herm. The total organic carbon (TOC) of sedimentary organic matter ranges between 0.07% and 1.96% with average of 0.21%. The organic matter types are Type I and Type III. The vitrinite reflectance (R0) of kerogen ranges between 0.99% and 2.03%, indicating the maturated and highly maturated stages. The analytical results of the representative samples collected from shelf and subtidal facies show that the differences of organic matter type and biological diagnostic compounds are related to the types of source rocks deposited in different paleoenvironments.