Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation

A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocate...     

A spectral mixture model analysis of the Kuroshio variability and the water exchange between the Kuroshio and the East China Sea

For understanding more about the water exchange between the Kuroshio and the East China Sea,We studied the variability of the Kuroshio in the East China Sea(ECS) in the period of 1991 to 2008 using a three-dimensional circulation model,and calculated Kuroshio onshore volume transport in the ECS at the minimum of 0.48 Sv(1 Sv ;106 m3/s) in summer and the maximum of 1.69 Sv in winter.Based on the data of WOA05 and NCEP,The modeled result indicates that the Kuroshio transport east of Taiwan Island decreased since 2000.Lateral movements tended to be stronger at two ends of the Kuroshio in the ECS than that of the middle segment.In addition,we applied a spectral mixture model(SMM) to determine the exchange zone between the Kuroshio and the shelf water of the ECS.The result reveals a significantly negative correlation(coefficient of-0.78) between the area of exchange zone and the Kuroshio onshore transport at 200 m isobath in the ECS.This conclusion brings a new view for the water exchange between the Kuroshio and the East China Sea.Additional to annual and semi-annual signals,intra-seasonal signal of probably the Pacific origin may trigger the events of Kuroshio intrusion and exchange in the ECS.     

A new ketosteroid from red alga Acanthophora spicifera

A new ketosteroid, along with six known steroids, was isolated from the ethanolic extracts of red alga Acanthophora spicifera (Vahl.) Boergesen. The structures, identified using chemical and spectroscopic methods including 2D NMR, were: (1) 22-hydroxy-5α-cholest-3,6-dione, (2) 6-hydroxycholest-4-ene-3-one, (3) cholest-4-ene-3,6-dione, (4) cholest-5-ene-3β-ol, (5) 5α-cholestane-3,6-dione, (6) β-Sitosterol and (7) Saringosterol. The MTT method was used to test the cytotoxicity of the compounds against the human cancer cell lines, HCT-8, Bel-7402, BGC-823, A549 and HELA. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity against human cancer cell lines.     

Synthesis and protein tyrosine phosphatase 1B inhibition activities of two new synthetic bromophenols and their methoxy derivatives

3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from 1H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2p-bromo-6p-(3q,4q-dimethoxybenzyl)- 3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(2),2,3-dibromo-1-(2p-bromo-6p-(2q-bromo-4q,5q-dimethoxy-benzyl)-3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(3),3,4-dibromo-5-(2p-bromo-6p-(2q-bromo-4q,5q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol(4)and 3,4-dibromo-5-(2p-bromo-6p-(3q,4q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol (5).PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay,and compounds 3 and 4 demonstrated interesting activity against PTP1B.     

Spatial and temporal variations in C3 and C4 plant abundance over the Chinese Loess Plateau since the last glacial maximum

Stable carbon isotopes of soil organic matter from 12 sites in the southern Chinese Loess Plateau are reviewed to examine spatial and temporal patterns of C₃ and C₄ plants in the arid to semiarid monsoonal region during three key periods - last glacial maximum, mid-Holocene, and modern. We have tentatively corrected the effects of atmospheric CO₂ concentrations and precipitation amounts on the δ¹³C endmembers for C₃ plants to reconstruct the relative proportion of C₄ plants because the δ¹³C values of C₃ plants are variable under different CO₂ and climate conditions. The results indicate that C₄ grasses increase from northwest to southeast spatially, which is consistent with present-day increasing precipitation and temperature patterns. This suggests that for a monsoon-dominant arid to semiarid region, such as the Loess Plateau, warm-season rainfall is a primary factor limiting C₄ plants growth, and thus C₄ grasses have been outcompeted by C₃ grasses/shrubs under cold-dry climate conditions. However, temporal fluctuations in atmospheric CO₂ concentration may also affect plant growth through altering water-use efficiency (WUE). Enhanced drought caused by decreased WUE due to low atmospheric CO₂ concentrations during glacial periods, combined with a cold-dry climate, leads to a decline in C₄ grasses, canceling out any advantages gained from lowered atmospheric CO₂ concentrations. To reconstruct accurately the abundance of C₃ and C₄ plants in an ecosystem and explore their controlling factors, process-based vegetation models integrating CO₂ and climatic parameters interactive with plant physiology are necessary.     

长江水氢、氧同位素组成的时空变化及其环境意义

在2003～2007年间,在长江干流的25个水文站及主要支流的13个水文站系统采样,进行了氢氧同位素研究。观测到的D变化范围为-30‰～-112‰,变化范围为-3.8‰～-15.4‰。从长江源头到河口,不同时期的样品均显示相同的氢氧同位素沿程变化特征。从源头到攀枝花,长江干流的D与逐步下降;而由攀枝花到入海口,D与值逐渐升高。 研究发现,控制长江水的氢氧同位素组成的主要因素是大气降水。长江干流D与值所展现的从攀枝花至河口逐渐升高的趋势就是对流域大气降水的D与变化趋势的响应。长江各支流在氢氧同位素组成上的差别及其对干流的影响也反映大气降水对长江水的制约。 蒸发作用对长江水的氢氧同位素组成也有重要影响。长江源头地处青藏高原,高原湖泊和沼泽星罗棋布。由于气候干燥、日照强烈,湖沼水经过长期的蒸发,盐度逐渐加大,D和18O值也逐渐升高。这些湖水的加入对长江水的氢氧同位素组成也造成一定影响。蒸发作用在枯水期也使洞庭湖与鄱阳湖的D和18O值升高,进而提高长江相关河段的D和18O值。 冰雪融化是影响长江水的氢氧同位素组成的另一重要因素。在长江源头和所有左岸支流的源头,冰川融雪都是重要的水源之一。由于冰川水在氢氧同位素组成上的特殊性,其对河水贡献的大小将影响河水的氢氧同位素组成。 三峡大坝对于长江的水动力体系影响巨大,三峡水库对长江水资源的调控作用有待长期观测研究。从本次的研究资料来看,三峡大坝在丰水期对相应河段的氢氧同位素变化趋势影响不大。但在枯水季节,三峡水库蓄水使下游的宜昌和沙市的水源发生明显变化,导致D和18O值的显著降低。 长江水资源状况及其演变趋势是受到各方面高度关注的重要研究课题。为深入探讨这一问题,需要了解长江水资源的变化与各种气象与水文要素之间的关系,查明大气降水、地下水、冰川水、湖水与河水之间的交互作用。而氢氧同位素示踪技术在这方面可以发挥关键性的作用。由于现有资料有限,目前还无法利用氢氧同位素组成来追溯其气候条件的详细演化过程。但若能在进行系统水文测量的同时,适当开展氢氧同位素测定,将对研究长江水资源状况及其演变趋势大有脾益。     

特提斯洋对流上地幔Os同位素组成估算的新方法及初步运用

对流上地幔Os同位素组成的准确估算是运用Re-Os同位素体系探讨地幔演化的基础。前人研究主要是以地幔橄榄岩为研究对象,由于地幔橄榄岩Os同位素存在明显的不均一性,因而直接影响估算值的准确性。对流上地幔中包含的不同亏损程度的难熔组分在部分熔融过程中难以熔融,对形成的熔体相的Os同位素组成贡献很少或者没有。因此,与对流上地幔具有相同的Os同位素组成初始值的早期分离结晶岩石(如堆晶岩),结合堆晶岩中锆石的准确定年,可以用来估算对流上地幔Os同位素组成。本文根据这一方法测试了那曲地区弧后盆地堆晶岩的Os同位素组成和锆石U-Pb年龄,推测那曲地区新特提斯洋对流上地幔Os同位素组成为碳质球粒陨石型的。根据这一模型,对比了罗布莎和东巧铬铁矿岩、含矿围岩以及不含矿围岩的Os同位素特征,揭示出矿石及围岩均具有古老大陆岩石圈地幔信息,而不含矿围岩(泽当岩体)的Os同位素组成为碳质球粒陨石型的,无古老大陆岩石圈地幔信息。     

MOR型蛇绿岩中地幔橄榄岩的地质特征

地幔橄榄岩是指来自陆下、弧下或洋脊下的岩石圈地幔岩,通常通过构造侵位(冷侵位)的方式存在于造山带中,如造山带橄榄岩、蛇绿岩中的橄榄岩以及火山岩中的地幔橄榄岩等。本文选取了4个具有MOR型属性的蛇绿岩中地幔橄榄岩体,对比研究了其与深海橄榄岩在岩石学、地球化学、同位素地球化学和岩石成因等方面的特征,认为与深海橄榄岩性质的综合对比是识别MOR型蛇绿岩中地幔橄榄岩的有效方法之一,同时在蛇绿岩的分类中具有较好的参考价值。     

Effects of fault activities on hydrocarbon migration and accumulation in the Zhu I Depression,Pearl River Mouth Basin,South China Sea

Faults can act as either conduits or barriers for hydrocarbon migration, because they have complicated anisotropic flow properties owing to their complicated three-dimensional structures. This study focuses on the Zhu I Depression, Pearl River Mouth Basin (PRMB), China. In this area, hydrocarbon migration and accumulation occurred over a relatively short period of time and were contemporaneous with fault activation, so the characteristics of hydrocarbon accumulations can be used to deduce the effect of active faults on hydrocarbon migration and accumulation. This study addresses the effect of fault activity on flow properties during hydrocarbon migration through a quantitative and comparative analysis of fault activity vs hydrocarbon accumulation. The fault slip rate and shale smear factor parameters were used to characterise faulting and elucidate its effect on hydrocarbon migration and accumulation. Active faults are generally excellent vertical conduits with strong fault activation resulting in vertical migration of most hydrocarbons and little preservation; traps near faults with fault slip rates greater than 20 m/Ma rarely contain commercial oil and gas accumulations. Faulting can form shale smear, which, if continuous, can act as a barrier to hydrocarbon migration. An active fault can allow hydrocarbon transport from deeper formations and to be trapped by continuous shale smear in shallower strata. Most of the oil and gas in the Zhu I Depression have accumulated near faults with a moderate fault slip rate (<20 m/Ma) and development of continuous shale smear (SSF<4–6).     

Quantifying time lag of epikarst-spring hydrograph response to rainfall using correlation and spectral analyses

Understanding spring-flow characteristics in karst areas is very important for efficient utilization of water resources. The time lag of a spring-hydrograph response to rainfall is related to karst hydrogeological properties such as thickness, porosity and hydraulic conductivity. The length of the time lag can be determined based on results of the time-series analysis. However, some approaches, with different identifying indicators, give different lengths of the time lag. In this study, the flow-discharge series of two hillslope springs located in a karst area of southwest China were used to compute lengths of the time lag. The thickness and porosity of the epikarst-zone fractures on the two hillslopes were estimated based on a ground-penetrating radar investigation and field measurement. Based on comparison of lengths of the time lag computed by auto- and cross-correlation analyses, the identifying indicators of the time lag were classified into three types for measuring short, intermediate and long-term responses of the spring hydrograph to rainfall. The study also reveals that the time lag of spring-hydrograph response to rainfall in the thick epikarst zone is much longer than that in the thin epikarst zone.