Closely-spaced recuperated OSL dating of the last interglacial paleosol in the southeastern margin of the Chinese Loess Plateau

The objective of this study is to construct a numerically dated chronology of the last interglacial paleosol (S₁) in Chinese loess using luminescence dating. The recuperated optically stimulated luminescence (ReOSL) dating approach was applied to 18 closely-spaced (20 cm intervals) samples, with 15 of these collected from the S₁ unit at the Weinan site, which is located at the southeastern margin of the Chinese Loess Plateau (CLP). By using the multiple-aliquot regenerative-dose (MAR) approach, 18 fine-grained quartz ReOSL equivalent dose (D_E) values, spanning about 249–466 Gy, were obtained. The validity of ReOSL MAR protocol was checked by dose recovery measurements and recycling ratio tests. By comparison of the dose-response curves of all the samples, we found that it is feasible to construct a standardized growth curve (SGC) for the ReOSL signal at the Weinan site. Considering the effects of pedogenesis of the S₁ unit during formation, the dose rate during the last interglacial was corrected, which should be beneficial for constructing a more reliable chronology. Finally, a detailed chronology of the S₁ unit was established. The results show that S₁ was deposited between approximately 76–127 ka, which confirms the early suggestion that the S₁ unit in Chinese loess corresponds to the whole marine oxygen-isotope stage (MIS) 5. The detailed ReOSL chronology of S₁ indicates the consistency of the substrata of S₁ with MIS 5a-e, but cannot determine whether they are exactly coeval. According to the present ReOSL age results, it is suggested that dust deposition is continuous at timescales larger than 14.1 ± 11.8 ky during the last interglacial and there is no hiatus longer than 4.4 ± 13.0 ky at the L₂/S₁ transition. Further work, e.g. minimizing the errors on ages and reducing the luminescence sampling intervals, is needed to understand the more detailed dust deposition conditions during the last interglacial in Chinese loess.     

A comparative study of toxicity identification using Daphnia magna and Tigriopus japonicus: implications of establishing effluent discharge limits in Korea

In Korea, the new permission criteria for industrial effluents based on Daphnia magna acute toxicity tests will be gradually implemented starting from 2011. Thus, in this study, toxicity assessment and identification using a marine species (Tigriopus japonicus) and the freshwater species (D. magna) was comparatively investigated. Effluent from an acid mine drainage treatment plant showed acute toxicity toward both organisms due to low pH, which was removed by neutralization of the effluent. Additionally, evaluation of the effluent of an electronics company revealed that Cu was attributable to the observed toxicity, and the effluent was more toxic toward T. japonicus than D. magna. Moreover, effluents from a metal plating factory were acutely toxic toward D. magna (6.50 TU), while they were not toxic against T. japonicus. Toxicity identification revealed that the high level of Cl- (12,841 mg L(-1)) was the cause of toxicity. Thus, the effluents had no effect on the marine species, T. japonicus. These findings suggest that a marine species rather than a freshwater species is more desirable for toxicity assessment of industrial effluent discharged into the saltwater, and thus should be considered in the legislation of toxicity-based discharge limits in Korea.     

中国东海海平面变化多尺度周期分析与预测

海平面变化规律尤其是对海平面变化周期和上升趋势的研究,已成为国内外科学界研究的热点问题.使用1992-2009年海平面卫星测高仪数据资料,运用小波变换方法对中国东海海平面变化的周平均数据信号进行多尺度周期分析,并通过Winters指数平滑法对未来海平面变化进行预测,结果显示:①1992-2009年东海海平面呈现波动上升...     

Groundwater simulation using a numerical model under different water resources management scenarios in an arid region of China

Groundwater plays an important role in the economic development and ecological balance of the arid area of northwest China. Unfortunately, human activity, for example groundwater extraction for irrigation, have resulted in excessive falls in groundwater level, and aquifer overdraft in the oasis, disrupting the natural equilibrium of these systems. A groundwater numerical model for Minqin oasis, an arid area of northwest China, was developed using FEFLOW software to simulate regional groundwater changes under transient conditions. The vertical recharge and discharge (source/sink terms) of the groundwater models were determined from land-use data and irrigation systems for the different crops in the different sub-areas. The calibrated model was used to predict the change for the period from 2000 to 2020 under various water resources management scenarios. Simulated results showed that under current water resources management conditions groundwater levels at Minqin oasis are in a continuous drawdown trend and groundwater depth will be more than 30 m by 2020. Reducing the irrigation area is more effective than water-saving irrigation to reduce groundwater decline at Minqin oasis and the annual groundwater budget would be −0.978 × 10⁸ m³. In addition, water-diversion projects can also reduce the drawdown trend of groundwater at Minqin oasis, and the groundwater budget in the Huqu sub-area would be in zero equilibrium if the annual inflow into the oasis was enhanced to 2.51 × 10⁸ m³. Furthermore, integrative water resources management including water-diversion projects, water-saving irrigation, and reducing the irrigation area are the most effective measures for solving groundwater problems at Minqin oasis.     

Partitioning tracer method for quantifying the residual saturation of refined petroleum products in saturated soil

The effective site assessment is crucial to the successful remediation of the subsurface contaminated with light nonaqueous phase liquids (LNAPLs). Recent studies showed that large spatial volumes of the subsurface contaminated with LNAPLs could be investigated with the partitioning tracer method. This study investigated the applicability of the partitioning tracer method for detecting and quantifying refined petroleum products in a saturated aquifer containing alluvial soil or weathered granite soil. In the batch-partitioning experiments, the partition coefficients of alcohol tracers between the petroleum mixture and water were measured, and they were found to be increased in proportion to the boiling points of the alcohol tracers when the molecular weights of the alcohol tracers were similar. The sorption isotherm experiments indicated that a considerable amount of 4-methyl-2-pentanol was sorbed into Jumunjin sand (JS) or weathered granite soil (WGS). In the column experiments, it was confirmed that the partitioning tracer method could be used as a method for detecting the presence of the petroleum mixture in saturated soil, and the residual saturation of the petroleum mixture in the soil column prepared by firstly contaminating with the petroleum mixture and secondly saturating with water was measured higher than that in the soil column prepared by firstly saturating and secondly contaminating. The highest accuracy of estimation using the partitioning tracer method was found for 2-ethyl-1-butanol and the lowest accuracy was found for 4-methyl-2-pentanol.     

Qualitative assessment of gas hydrate and gas concentrations from the AVO characteristics of the BSR in the Ulleung Basin, East Sea (Japan Sea)

The presence of gas hydrate in the Ulleung Basin, East Sea (Japan Sea), inferred by various seismic indicators, including the widespread bottom-simulating reflector (BSR), has been confirmed by coring and drilling. We applied the standard AVO technique to the BSRs in turbidite/hemipelagic sediments crosscutting the dipping beds and those in debris-flow deposits to qualitatively assess the gas hydrate and gas concentrations. These BSRs are not likely to be affected by thin-bed tuning which can significantly alter the AVO response of the BSR. The BSRs crosscutting the dipping beds in turbidite/hemipelagic sediments are of low-seismic amplitude and characterized by a small positive gradient, indicating a decrease in Poisson’s ratio in the gas-hydrate stability zone (GHSZ), which, in turn, suggests the presence of gas hydrate. The BSRs in debris-flow deposits are characterized by a negative gradient, indicating decreased Poisson’s ratio below the GHSZ, which is likely due to a few percent or greater gas saturations. The increase in the steepness of the AVO gradient and the magnitude of the intercept of the BSRs in debris-flow deposits with increasing seismic amplitude of the BSRs is probably due to an increase in gas saturations, as predicted by AVO model studies based on rock physics. The reflection strength of the BSRs in debris-flow deposits, therefore, can be a qualitative measure of gas saturations below the GHSZ.     

香港巨牡蛎ISSR-PCR反应体系的建立及优化

以香港巨牡蛎（Crassostreahongkongensis）基因组DNA为模板,采用正交设计及单因素比较试验,分别对Mg^2＋、dNTPs、引物、TaqDNA聚合酶和DNA模板浓度的PCR原料进行优化,并通过温度梯度PCR,筛选适宜的退火温度。确立了香港巨牡蛎的最适ISSR—PCR反应体系：25μL反应体系中含PC...     

单立柱张力腿平台水动力性能试验研究

通过耐波性水池进行单立柱张力腿平台(简称SCTLP)在系泊状态下的运动特性,以及张力筋键受力情况的试验研究。试验分别在规则波和不规则波(长峰波和短峰波)中进行,浪向选取180°。根据水池深度,模型试验采用1∶87.5的缩尺比进行全水深模拟,并对风力和流速进行了模拟。通过试验,获得较为丰富的试验数据,能很好地分析SCTLP的运动特性。     

Temperature and thermal growing season variations along elevational gradients on a sub-alpine,temperate China

Fully and accurately studying temperature variations in montane areas are conducive to a better understanding of climate modeling and climate-growth relationships on regional scales. To explore the spatio-temporal changes in air and soil temperatures and their relationship in montane areas, on-site monitoring over 2 years (2015 and 2016) was conducted at nine different elevations from 2040 to 2740 m a.s.l. on Luya Mountain in the semiarid region of China. The results showed that the annual mean of air temperature lapse rate (ATLR) was 0.67 °C/100 m. ATLR varied obviously in different months within a range of 0.57~0.79 °C/100 m. The annual mean of the soil temperature lapse rate (STLR) was 0.48 °C/100 m. Seasonally, monthly mean soil temperature did not show a consistent pattern with regard to elevation. The relationships between air and soil temperatures showed piecewise changes. Soil was decoupled from the air temperature in cold winter and early spring. The parameters of the growing season based on the two temperature types had no corresponding relations, and seasonal mean of soil temperature showed the smallest value at mid-elevation rather than in the treeline ecotone. Based on these changes, our results emphasized that altitudinal and seasonal variability caused by local factors (such as snow cover and soil moisture) should be taken into full consideration in microclimate extrapolation and treeline prediction in montane areas, especially in relation to soil temperature.