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[en] In view of the unclear division of sequence stratigraphy and the unclear understanding of sedimentary characteristics of Shahezi Formation in Xu Dong of Xujiaweizi fault depression, a detailed study on the division of sequence stratigraphy of Shahezi Formation in Xu Dong area of Xujiaweizi fault depression was carried out by using the data of Vail sequence stratigraphy. The sedimentary facies types and plane distribution characteristics of Xu Dong area were analyzed in combination with single well facies and material source supply, etc. The study showed that Shahezi Formation in Xu Dong area could be divided into a second-order sequence, and the interior could be further divided into four third-order sequences. At the early stage of sedimentation, the lake water was relatively deep and fan delta sedimentary system was mainly developed. In the middle period, the lake basin became wider and fan delta and braided river delta sedimentary systems developed. In the late period, the lake basin was basically stable and braided river delta sedimentary system was developed. (paper)
[en] A heat danger day is defined as an extreme when the heat stress index (a combined temperature and humidity measure) exceeding 41 °C, warranting public heat alerts. This study assesses future heat risk (i.e. heat danger days times the population at risk) based on the latest Coupled Model Intercomparison Project phase 6 projections. In recent decades (1995–2014) China’s urban agglomerations (Beijing-Tianjin-Hebei, Yangtze River Delta, Middle Yangtze River, Chongqing-Chengdu, and Pearl River Delta (PRD)) experienced no more than three heat danger days per year, but this number is projected to increase to 3–13 days during the population explosion period (2041–2060) under the high-emission shared socioeconomic pathways (SSP3-7.0 and SSP5-8.5). This increase will result in approximately 260 million people in these agglomerations facing more than three heat danger days annually, accounting for 19% of the total population of China, and will double the current level of overall heat risk. During the period 2081–2100, there will be 8–67 heat danger days per year, 60%–90% of the urban agglomerations will exceed the current baseline number, and nearly 310 million people (39% of the total China population) will be exposed to the danger, with the overall heat risk exceeding 18 times the present level. The greatest risk is projected in the PRD region with 67 heat danger days to occur annually under SSP5-8.5. With 65 million people (68% of the total population) experiencing increased heat danger days, the overall heat risk in the region will swell by a factor of 50. Conversely, under the low-emission pathways (SSP1-2.6 and SSP2-4.5), the annual heat danger days will remain similar to the present level or increase slightly. The result indicates the need to develop strategic plans to avoid the increased heat risk of urban agglomerations under high emission-population pathways. (letter)
[en] The microtremor horizontal-to-vertical spectral ratio (HVSR, or H/V spectral ratio) method is an effective tool for detecting sediment thickness. Firstly, single-station microtremor measurements were taken beside 52 boreholes located in Pearl River Delta, China. Sediment thicknesses revealed by those boreholes range from 7.9 to 39.6 m. Then, those microtremor data were analyzed using HVSR method, and peak frequency of each site was extracted. According to those peak frequencies of HVSR and corresponding sediment thicknesses, the frequency-to-thickness fitting (f–Z) equation which is suitable for Pearl River Delta area was established. And this equation was compared with several fitting equations derived from different regions by other researchers. Finally, this fitting equation was applied in a collapse area in Guangzhou city to estimate site sediment thickness. Compared with data from five boreholes in this collapse area, the consistency between estimated sediment thickness and real value was relatively good. Karst sinkholes are generally located in regions where thickness of sediments is shallow. Therefore, the method described in this paper can provide support for delineating potential collapse areas.
[en] We assess the issues of urban effects on the precipitation over the Pearl River Delta (PRD) metropolitan regions of China. The spatial and temporal variations of strong versus weak precipitation over the PRD and surrounding nonurban areas are investigated. The results show that the urbanization signatures in strong precipitation are significantly different from those in weak precipitation over the urban areas. The PRD experiences more strong precipitation but less weak precipitation compared to surrounding nonurban regions. In addition, the strong precipitation over the PRD displays a pronounced seasonal variation. The seasonality of weak precipitation, however, is much weaker over the PRD compared to the surrounding nonurban regions. Moreover, a strengthening in the precipitation intensity, a reduction in the rainfall frequency and an increase in the convective precipitation as well as the afternoon precipitation are found over the urban areas, which are probably associated with the abundance in strong precipitation and the deficit in weak precipitation over the PRD.
[en] Concentrations of ten metals were evaluated in surface sediments along Cauto River by dispersive energy X-Rays Fluorescence using External Standard Method. The results showed that heavy metal concentrations (in mg/kg; Fe in %) were 1.46-2.77, 8.8-12.0, 16-25, 117-140,35-56, and 40-48. for Fe, Co, Ni, Cu, Zb and Pb respectively, generally decreasing along the course of the river. Geo accumulation indexes were categorized between strongly to very strongly polluted for Cu and Co in all the stations. The calculation of enrichment factors (EF) showed that Co and Cu were enriched whereas the others metals were depleted. Concentrations of Cu and Ni were higher than Effect range low (ERL) but still below Effect range medium (ERM) value established by NOAA. Heavy metal concentrations found in the present study were comparable to other zones of the country and other regions of the world. In the last years, a considerable increase of Pb concentrations was found indicated more anthropogenic inputs. Based on the calculated indexes, Cauto River zone can be classified as unpolluted to moderately polluted environment. (Author)
[en] To elucidate the role of genetic factors in arsenic metabolism, we investigated associations of genetic polymorphisms in the members of glutathione S-transferase (GST) superfamily with the arsenic concentrations in hair and urine, and urinary arsenic profile in residents in the Red River Delta, Vietnam. Genotyping was conducted for GST ω1 (GSTO1) Ala140Asp, Glu155del, Glu208Lys, Thr217Asn, and Ala236Val, GST ω2 (GSTO2) Asn142Asp, GST π1 (GSTP1) Ile105Val, GST μ1 (GSTM1) wild/null, and GST θ1 (GSTT1) wild/null. There were no mutation alleles for GSTO1 Glu208Lys, Thr217Asn, and Ala236Val in this population. GSTO1 Glu155del hetero type showed higher urinary concentration of AsV than the wild homo type. Higher percentage of DMAV in urine of GSTM1 wild type was observed compared with that of the null type. Strong correlations between GSTP1 Ile105Val and arsenic exposure level and profile were observed in this study. Especially, heterozygote of GSTP1 Ile105Val had a higher metabolic capacity from inorganic arsenic to monomethyl arsenic, while the opposite trend was observed for ability of metabolism from AsV to AsIII. Furthermore, other factors including sex, age, body mass index, arsenic level in drinking water, and genotypes of As (+ 3 oxidation state) methyltransferase (AS3MT) were also significantly co-associated with arsenic level and profile in the Vietnamese. To our knowledge, this is the first study indicating the associations of genetic factors of GST superfamily with arsenic metabolism in a Vietnamese population.
[en] To clarify the current situation of haze emission and governance in China, the study analyzed the characteristics of spatial correlation structure and synergistic governance development of the haze emission of 31 provinces in China, based on social network analysis and distance synergistic model. The results indicated that the spatial correlation of inter-provincial haze emission in China presented a typical “central–marginal” network structure. The provinces in the network center were mostly located in the Beijing–Tianjin–Hebei region and the Yangtze River Delta region. The synergistic governance development of haze in China showed a lower level and fluctuating upward trend. In addition, the increase of network density, the decline of network grade, and the decrease of network efficiency would all improve the level of synergistic governance development. Therefore, focusing on the haze of the central provinces, improving the network structure, and improving regional synergy are important measures for effective governance. This paper improves the previous research model, considers the impact of economic and demographic factors on haze pollution, establishes a new model for analyzing spatial correlation structure of haze and calculating the synergistic governance level of haze, and designs feasible ways to raise the synergistic governance level of haze in China.
[en] Firstly, this paper gave a brief review of the core issues of previous studies on spatial distribution of knowledge spillovers. That laid the theoretical foundation for further research. Secondly, this paper roughly described the diffusion process of solar patents in Bejing-Tianjin-Hebei and the Pearl River Delta regions by means of correlation analysis based on patent information of the application date and address of patentee. After that, this paper introduced the variables of spatial distance, knowledge absorptive capacity, knowledge gap and pollution control and built the empirical model of patent, and then collecting data to test them. The results showed that knowledge absorptive capacity was the most significant factor than the other three, followed by the knowledge gap. The influence of spatial distance on knowledge spillovers was limited and the most weak influence factor was pollution control. (paper)
[en] Water movement in soils at the lower course and the middle course of Sakawa River's paddy field was monitored over an 8 week period using a bromide tracer. The water of soil samples taken one day after bromide application contained high concentrations of bromide at 50 to 60 cm soil depth at lower course. The bromide was concentrated promarily within 20 to 80 cm depth. No downward movement below 80 cm depth was detected six weeks afetr the application. This might indicate the high water table of this area. On the other hand, bromide concentrations were high at 50 cm depth in water of the soils sample taken one day after application from the middle course of Sakawa River plot. However, the concentrations were nearly at background level in all samples taken from the middle course of sakawa River 3 weeks after application. The evidence from bromide's movement shows that water readily penetrate the soils at the middle course of Sakawa River. The downward movement was faster compared to that at lower course