石羊河流域中下游地区地下水位动态特征及变化趋势

依据石羊河流域中下游地区64个观测点30年（1978-2007）的地下水位观测资料,定量分析了地下水位的季节性动态特征和多年变化规律及其分布地带,将季节性动态划分为径流、开采、灌溉一开采、蒸发4种类型,多年动态划分为快速下降、缓慢下降和基本稳定3种类型。采用灰色理论建立了所有观测点地下水位的灰色残差修JEGM（1,1）预报模型并进行了预报。预报至2010年,石河河流域中下游地区的地下水位仍将处于不断下降过程,但下降幅度较1978-2007年有所减缓,部分地带地下水位可能趋于稳定。预报结果对于改善流域特别是下游民勤绿洲的生态与环境将起到积极的影响。     

荒漠植物生活史对策研究进展与展望

植物种群生活史是指植物种群从种子萌发到种子形成所经历的全部过程,它包括植物种群生活周期各个阶段(繁殖、种子、补充与生长)的生活史特征以及与同一生境内其他生物之间和环境的相互作用。而生活史对策是生物在长期的自然选择下形成的、以各种生活史特征表现出来的适应对策,即由自然选择塑造的生物体外形和习性。本文综述了国内外植物生活史对策的研究历史、进展和生活史对策的研究内容以及生活史对策理论在荒漠植物研究中的应用。指出生活史研究仍存在不足首先是研究内容上,资源分配在多年生植物中的权衡仍未被有力证明,邻体效应与繁殖分配的关系在个体水平上仍不明了,多年生植物在不同邻体效应和生境下将采取何种繁殖对策目前尚无明确的结论;繁殖分配与性分配之间的关系,引起花序结构上资源分配差异的原因,各种繁殖对策中繁殖分配异同与维持机制等问题仍有待于进一步的研究;种子大小的变异机制以及生物学意义仍未得到令人满意的答复,更需分子水平上的研究来解释其机理。在群落水平上种子大小与萌发能力的关系不明确,萌发过程的时间扩散方式报道甚少。因此,这些方面的研究工作急待加强。     

Persistent organochlorine pollutants in Korean offshore waters: Squid (Todarodes pacificus) as a biomonitor

Persistent organochlorine pollutants (POPs) such as polychlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), and hexachlorocyclohexanes (HCHs) were determined in Japanese common squid collected from the offshore waters of Korea. Liver accumulated higher levels of contaminants than mantle. The sums of DDTs, PCBs, CHLs and HCHs in liver were in the ranges of 164-4430 ng g⁻¹, 95-1030 ng g⁻¹, 15-121 ng g⁻¹, and 13-98 ng g⁻¹ on a lipid weight basis, respectively. Among the POPs, DDTs showed distinct regional difference in concentration levels and composition between the western and eastern offshore of Korea. One of the highest concentrations of DDTs so far recorded in the western offshore of Korea, that is Yellow Sea. This implies ongoing fresh input of technical DDT to this regional sea. HCHs were relatively high in the Yellow Sea as well, with an enhanced signal of γ-HCH indicating recent input of lindane. In contrast, CHLs showed higher level in the eastern offshore of Korea, that is East Sea, but PCBs showed an even distribution in both regions. Squid could be a useful bio-indicator for monitoring offshore water contamination by POPs.     

High incorporation of carbon into proteins by the phytoplankton of the Bering Strait and Chukchi Sea

High incorporation of carbon into proteins and low incorporation into lipids were a characteristic pattern of the photosynthetic allocations of phytoplankton throughout the euphotic zone in the Bering Strait and Chukchi Sea in 2004. According to earlier studies, this indicates that phytoplankton had no nitrogen limitation and a physiologically healthy condition, at least during the cruise period from mid-August to early September in 2004. This is an interesting result, especially for the phytoplankton in the Alaskan coastal water mass-dominated region in the Chukchi Sea which has been thought to be potentially nitrogen limited. The relatively high ammonium concentration is believed to have supported the nitrogen demand of the phytoplankton in the region where small cells (<5 μm) composed of about 50% of the community, since they prefer to use regenerated nitrogen such as ammonium. In fact, a small cell-size community of phytoplankton incorporated much more carbon into proteins in nitrate-depleted water suggesting that small phytoplankton had less nitrogen stress than large phytoplankton. If the high carbon incorporation into proteins by the phytoplankton in 2004 is a general pattern of the photosynthetic allocations in the Chukchi Sea, they could provide nitrogen-sufficient food for the highest benthic faunal biomass in the Arctic Ocean, sustaining large populations of benthic-feeding marine mammals and seabirds.     

Changes in topography and surface sediments by the Saemangeum dyke in an estuarine complex,west coast of Korea

The effects of a giant offshore dyke, Saemangeum, have been of special interest on both scientific and environmental aspects. Without any rival worldwide with regard to the ample scale and estuarine setting, the Saemangeum dyke and its vicinity (Saemangeum Area) should be an unprecedented experimental site for monitoring the consequence of the estuarine developments with dykes. In order to unravel geologic changes caused by the Saemangeum dyke, we collected a number of surface sediment samples and bathymetric profiles from a full coverage of the Saemangeum Area, and compared topography and sediment phase on the inter-annual (2002–2006, post-construction) and decadal (1982–2002, between pre- and post-construction) timescales.     

����ʱƵ����������GNSS/INS��ϵ��������˲�ģ��

??????????????????Kalman??????????????????????????Kalman?????????????????????????????????????????????????????????????GNSS/INS?????????????????????????????????????????????????????????????????????????????????????????Kalman??????????????     

Determination of critical shear stress of non‐cohesive soils using submerged jet test and turbulent kinetic energy

Laboratory tests using Jet Erosion Testing (JET) apparatus, impinging normally on a horizontal boundary, were conducted to determine the critical shear stress (τ_c) of non‐cohesive soil samples. A three‐dimensional (3D) SonTek/YSI 16 MHz Micro‐Acoustic Doppler Velocimeter (MicroADV) was used to measure turbulent kinetic energy (TKE) at a radial limit of entrainment in the wall jet zone and the measurements were used to calculate τ_c of the samples. The results showed that TKE increases exponentially with increasing particle size. The τ_c from this study were comparable (R² = 0.8) to the theoretical τ_c from Shields diagram after bed roughness scale ratio (D/k_s), due to the non‐uniform bed conditions, was accounted for. This study demonstrated that JET and TKE can be used to determine τ_c of non‐cohesive soils. The use of JET and TKE was found to be faster and easier when compared to the conventional approach of using flumes. A relationship of TKE at the onset of incipient motion (TKE_c) and samples’ D₅₀ developed in this study can be used to predict τ_c of non‐cohesive soils under similar non‐uniform conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

Geochemical Distribution of Trace Elements in Groundwater from the North Mara Large‐Scale Gold Mining Area of Tanzania

The influence of large‐scale mining operations on groundwater quality was investigated in this study. Trace element concentrations in groundwater samples from the North Mara mining area of northern Tanzania were analyzed. Statistical analyses for relationships between elemental concentrations in the samples and distance of a sampling site from the mine tailings dam were also conducted. Eleven trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined, and averages of Fe and Al concentrations were higher than levels accepted by the Tanzanian drinking water guideline. Levels of Pb in three samples were higher than the World Health Organization (WHO) and United States Environmental Protection Agency (USEPA) drinking water guidelines of 10 and 15 µg/L, respectively. One sample contained a higher As level than the WHO and USEPA guideline of 10 µg/L. The correlation between element concentrations and distance from the mine tailings dam was examined using the hierarchical agglomeration cluster analysis method. A significant difference in the elemental concentration existed depending on the distance from the mine tailings dam. Mann–Whitney U‐test post hoc analysis confirmed a relationship between element concentration and distance of a sampling site from the mine tailings dam. This relationship raises concerns about the increased risks of trace elements to people and ecosystem health. A metal pollution index also suggested a relationship between elemental concentrations in the groundwater and the sampling sites’ proximity from the mine tailings dam.     

An efficient method for selecting and scaling ground motions matching target response spectrum mean and variance

The purpose of this study is to propose an accurate and efficient method for selecting and scaling ground motions matching target response spectrum mean and variance, which does not require excessive computation and simulation. In the proposed method, a desired number of ground motions are sequentially scaled and selected from a ground motion library without iterations. Copyright © 2016 John Wiley & Sons, Ltd.     

Erosion control for mudstone soil with ventilation and watertight resin

To accelerate the re-vegetation of exposed landslide areas, hydroseeding for soil and water conservation has been widely applied as one of the economically feasible ways. However, effect durations of different hydroseeding materials are different, the formulation density has a certain effect on plant growth and the addictives may exude. This paper presents laboratory experiments of soil erosion, exuding water quality and soil hardness by using a rainfall simulator with different conditions of slope, rainfall intensity and medication density. The results showed that soil erosion decreased significantly, suggesting a good erosion-resisting effect by the ventilation and watertight resin. No significant variation of the exuded water was observed during testing, which indicates that after gelling, the ventilation and watertight resin are unlikely to release chemical substances. It was found that high resin density will result in poor workability as well as high costs; adverse will cause the mudstone to fracture due to raindrops since cracks are common to soil surface. The weatherability after spraying and its effect on plant vegetation still need further investigation.