Results 1 - 10 of 2015
Results 1 - 10 of 2015. Search took: 0.026 seconds
|Sort by: date | relevance|
[en] In this study, field measurements were made and environmental isotopes and radiological properties were determined in six selected wells located in the coastal area south of Beirut, the capital of Lebanon. It is one of the many district areas in Lebanon, threatened by the penetration of seawater into aquifers. Two sampling campaigns were carried out to determine possible seasonal variations. High electrical conductivity was observed, ranging from 1080 to 7900 μS/cm. The total dissolved solids values ranged from 530 to 5600 mg/L. This is attributed to a seawater intrusion confirmed by high chlorine concentrations that ranged from 400 to 3500 mg/L. Isotope data for δ"1"8O/δ"2H showed enrichment that is relatively small at the end of wet season due to recharge by local precipitation and infiltration. Carbon-14 ages and "2"3"4U/"2"3"8U ratios confirmed the presence of young water. No radiological hazard was observed as all values lay below the guidance levels of the WHO.(author)
[en] In the original publication, the reference “Gregoretti C, Fontana GD (2008) The triggering of debris flow due to channel-bed failure in some alpine headwater basins of the Dolomites: analyses of critical runoff. Hydrol Process 22(13):2248–2263” is published wrong.
[en] The present work compares the performance of two alternative flow models for the simulation of thermal-hydraulic coupled processes in low permeable porous media: non-isothermal Richards and two-phase flow concepts. Both models take vaporization processes into account: however, the Richards model neglects dynamic pressure variations and bulk flow of the gaseous phase. For the comparison of the two approaches first published data from a laboratory experiment is studied involving thermally driven moisture flow in a partially saturated bentonite sample. Then a benchmark test of longer-term thermal-hydraulic behavior in the engineered barrier system of a geological nuclear waste repository is analyzed (DECOVALEX project). It was found that both models can be used to reproduce the vaporization process if the intrinsic permeability is relative high. However, when a thermal-hydraulic coupled problem has the same low intrinsic permeability for both the liquid and the gas phase, only the two-phase flow approach provides reasonable results.
[en] The article “Polybrominated diphenyl ethers and its methoxylated analogues in biota and sediment samples from two freshwater lakes in Yangtze River delta, written by Xinyu Du, Hong Chang, Yihui Zhou, Yanling Qiu, Yan Wu, Zhifen Lin, Zhiliang Zhu and Jianfu Zhao, was originally published
[en] The ancient City Wall of Nanjing (CWN) has suffered various damages since it was built more than 600 years ago. Numerous fractures and dislocations can be found on the wall. Furthermore, deterioration or destruction on several segments of the wall often occurred soon after restoration work was done, and brings some threats again and again on the people who either walk or live near the wall. The characteristics of these damages and their causes are unclear. In this paper the major fractures and dislocations on CWN were investigated through a field survey. It was observed that the apertures and dislocations of the CWN are usually large near the ground surface and decrease upwards and the most active fractures are located in the segments of the wall along a fault in NWW direction (290°). Twelve joint meters were installed across those fractures and the changes of the fractures’ aperture were measured monthly from April, 2010 to December, 2011. The measured data show that the fractures’ apertures are changing with time significantly, and the maximum cumulative change of apertures is 2.3 mm during 20 months. 80 bases were installed for the GPS measurement on top of the wall, and each site was measured monthly for the same time period as the joint meter measurements, the position of the wall moves significantly with time and the range of the displacement is ± 15.00 mm with the largest value of 20.00 mm. Based on the field survey and measurement, it is hypothesized that the changes of the fractures’ aperture of the wall were caused by the non-uniform crustal movement. A three-dimensional mechanical modeling was built to test the hypothesis and the results confirmed the field observation. The findings from this study are significant and important to protect ancient walls and other human-made structures since the crustal movement may have never been considered before.
[en] The increasing usage and disposal of plastic products could cause the wide distribution of phthalate esters (PAEs) in various environmental media. In this study, six PAE compounds, namely dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, benzyl butyl phthalate, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate, were analyzed in various samples collected from the major plastic industrial area of southern Taiwan, including soil, fertilizer and plastic products, for the purposes of identifying of the possible sources of PAEs and assessing the related health risk. The results show that PAEs in soil samples was dominated by DEHP, with the total concentrations in the range of 0.7 ± 0.5, 0.2 ± 0.1, and 0.3 ± 0.2 mg kg−1 for soil samples from farmland, household back gardens and the roadside, respectively. Contents of PAEs in chemical fertilizer (ND—0 0.87 mg kg−1) were higher than that in organic fertilizer (ND—0.08 mg kg−1), and PAEs concentrations (ND—316 mg kg−1) in plastic mulching films were much less than those in the other types of plastic products (ND—1719 mg kg−1), implying that major sources of PAEs in agricultural soil could be the use of chemical fertilizer and plastic products other than plastic mulching films. Health risk assessment suggested that, via the exposure to PAEs in soil, the potential non-cancer and carcinogenic risks for adults and children are minimal in most cases, except that a “moderate” carcinogenic risk for children exposure to DEHP. The results of this study can serve as a reference for further pollution prevention and environmental protection plans in relation to the industrial operation and discharge as well as the farming practices.