Sources and pathways of natural and anthropogenic hydrocarbons into the natural dump Arkona Basin (southern Baltic Sea)

 Surface sediments, suspended particulate matter and fluffy-layer material, collected in the Arkona Basin and the Pomeranian Bay during 1995–1997, as well as air particulate matter, collected on the island of Rügen during August 1995, were analysed for total organic carbon content, saturated and polycyclic aromatic hydrocarbons (PAH). The resulting concentrations and distributions of these compounds and molecular PAH ratios are discussed in terms of matrix, origin of the organic matter and seasonal variations. The data show that the Oder river can be identified as a major source for PAH transported into the southern part of the Arkona Basin. A strong atmospheric input of PAH is noted for the central and northern part of the basin. In general, anthropogenic and bacterially degraded hydrocarbons bound to organic carbon-rich and small particles are mainly deposited in the basin center, whereas their natural counterparts accumulate mainly on the basin flanks covered by coarser grained sediments. Received: 2 March 1999 · Accepted: 8 June 1999     

渤海悬浮颗粒物的三维输运模式 I.模式

为了长时间,大范围研究渤海中悬浮物的输运规律,研究应用并改造了备国汉堡大学的粒子追踪悬浮物输运的三维模式,模式中考虑了风、气压等气象要素以外海传入的潮波作用下的三维正压海流对悬浮颗粒物的输运．同时考虑了悬浮颗粒物的学降及再悬浮机制和底质中的细颗粒物的运动,将风浪的作用引入了悬浮物输运的计算,数值模式应用的粒五追踪方法,能较好地反映悬浮物浓度的迅速变化。     

多尺度天气分析理论和应用Ⅱ:锋面和气旋的形成机制

利用多尺度天气分析理论,研究了锋面和气旋的形成机制.结果表明,冷、暖气团是由不同性质的亚微团在环境力的作用下向不同方向运动而形成的,而它们的交界面就是锋面.急流附近强动能梯度力能促进微团的分离,因此锋面与急流有很好的对应关系.另外,低空急流附近存在上干冷下暖湿的稳定气流,原因在于急流之上的能量梯度力与重力的方向相反,导致该区域微团所受到的作用力为零,形成稳定的结构.但当微团运动到急流出口处时,这种平衡不再存在,暖湿微团向上运动而干冷微团向下运动,形成剧烈的天气变化.地球自转所形成的离心力使得轻微团产生向北、向上的运动分量,导致极锋向北倾斜.气旋的形成同样是由亚微刚的分离而产生的.当轻微团离开微团,在绝对环境涡度场的作用下将发生旋转,旋转的方向与初始涡度的方向一致,在北半球地转涡度的垂直分量向上,为逆时针旋转,南半球为顺时针旋转.在气旋的形成过程中,轻亚微团在气压梯度力场和绝对涡度力的作用下呈现螺旋运动,是气旋系统普遍存在螺旋云带和雨带的原因.水汽是气旋在形成和加强过程中的基本能源,由于发生地的不同,温带气旋和台风在水汽输送方式上亦有差别:温带气旋主要依靠低空暖输送带进行水汽输送;台风因为发生在热带海洋,水汽充沛,各个层次都有水汽供应.气旋运动主要受三个力的制约:环境气压梯度场力、绝对涡度场力和环境涡度力,这三个力的作用导致台风在沿副热带高压边缘运动的同时,还存在蛇形路径和打转运动.     

绿色交通目标下集装箱“公转铁”的CO2减排潜力评估

为提高集装箱“公转铁”减排潜力评估结果的准确性,在分析“公转铁”减排原理的基础上,综合考虑空箱调运和重箱运输“门到门”运输链的干线运输、端点装卸、电力设备作业、集卡短驳、公铁中转等排放,引入反映活动类型、设备结构、能源生命周期排放的参数,对作业活动-方式结构-能耗强度-排放因子（ASIF）方法进行改进,建立“公转铁”减排潜力评估框架。以义乌—宁波港域出口集装箱运输为例,通过实地调研和公开文献获取数据,进行实证研究。结果表明,如果忽略必要因素将会导致每TEU运输需求“公转铁”的CO₂减排率被高估0.50~36.73个百分点;最佳“公转铁”情景可减排3.42万t CO₂,相应减排率为13.58%。研究结果可为政府相关部门客观评估“公转铁”的减排潜力、制定有效的“公转铁”政策措施提供理论支持。     

Approximations to the ocean’s residual circulation in arbitrary tracer coordinates

The residual circulation is the flow which transports tracers. Its utility is tempered by the challenge associated with its computation: velocity must be mapped into tracer coordinates on a timescale which is short compared to eddy timescales. Several approximations have been introduced which allow the residual circulation to be evaluated using a small number of flow statistics, including the transformed Eulerian mean (TEM), the temporal residual mean (TRM), and the recently introduced statistical transformed Eulerian mean (STEM). This paper discusses the relationship between these approximations and illustrates their differences with a series of analytical and numerical examples. The STEM is found to be superior to the TEM and TRM in both its handling of the surface boundary condition and its ease of implementation.     

Using global node-based velocity in random walk particle tracking in variably saturated porous media: application to contaminant leaching from road constructions

Precise and efficient numerical simulation of transport processes in subsurface systems is a prerequisite for many site investigation or remediation studies. Random walk particle tracking (RWPT) methods have been introduced in the past to overcome numerical difficulties when simulating propagation processes in porous media such as advection-dominated mass transport. Crucial for the precision of RWPT methods is the accuracy of the numerically calculated ground water velocity field. In this paper, a global node-based method for velocity calculation is used, which was originally proposed by Yeh (Water Resour Res 7:1216–1225, 1981). This method is improved in three ways: (1) extension to unstructured grids, (2) significant enhancement of computational efficiency, and (3) extension to saturated (groundwater) as well as unsaturated systems (soil water). The novel RWPT method is tested with numerical benchmark examples from the literature and used in two field scale applications of contaminant transport in saturated and unsaturated ground water. To evaluate advective transport of the model, the accuracy of the velocity field is demonstrated by comparing several published results of particle pathlines or streamlines. Given the chosen test problem, the global node-based velocity estimation is found to be as accurate as the CK method (Cordes and Kinzelbach in Water Resour Res 28(11):2903–2911, 1992) but less accurate than the mixed or mixed-hybrid finite element methods for flow in highly heterogeneous media. To evaluate advective–diffusive transport, a transport problem studied by Hassan and Mohamed (J Hydrol 275(3–4):242–260, 2003) is investigated here and evaluated using different numbers of particles. The results indicate that the number of particles required for the given problem is decreased using the proposed method by about two orders of magnitude without losing accuracy of the concentration contours as compared to the published numbers.     

Terbuthylazine and Deethylterbuthylazine in Rain and Surface Water – Determination by Enzyme Immunoassay and Gas Chromatography/Mass Spectrometry

Rain and surface water samples from Southern Germany were investigated from 1991 to 1995 for terbuthylazine and one of its major metabolites, deethylterbuthylazine. The concentrations observed were compared to the concentrations found for atrazine and deethylatrazine in the same water samples. Concentrations ranged from < 0.02 μg/L to 0.7 μg/L for terbuthylazine and from < 0.02 μg/L to 0.6 μg/L for deethylterbuthylazine, compared to concentrations of < 0.02 μg/L to 3 μg/L and < 0.02 μg/L to 0.5 μg/L for atrazine and deethylatrazine, respectively. The ratios of metabolite concentrations to parent compound concentrations were calculated for deethylterbuthylazine to terbuthylazine (DTR) and deethylatrazine to atrazine (DAR). In rain water, DTR of 0.8…3.0 and DAR of 0.3… 1.9 were determined with mean values of 0.9… 1.7 for DTR and 0.6…0.9 for DAR in the different years. The ratios increased during summer periods. The highest ratios were observed in samples from forest stands, showing that degradation of the herbicide has occurred during transport between the source and the sampling site. The DTR in rain water were about 50… 100% higher than the DAR. This indicates a higher degradation rate of terbuthylazine during atmospheric transport. In surface water, DTR of 0.3… 1.2 with mean values of 0.5…0.8 and DAR of 0.2…2.2 with mean values of 0.2… 1.3 were observed. The ratios increased from June to September.     

Distribution and transport patterns of northern rock sole, Lepidopsetta polyxystra, larvae in the southeastern Bering Sea

We report the size, abundance, and distribution (horizontal, vertical) of northern rock sole, Lepidopsetta polyxystra, larvae collected from ichthyoplankton surveys on the southeastern Bering Sea shelf near Unimak Island, in Unimak Pass, and in the Gulf of Alaska south of Unimak Island. The greatest abundances of larvae occurred within Unimak Pass and in the Bering Sea northeast of Unimak Island. Larvae were smaller and more abundant in 2002 than in 2003. Larval abundance and size varied with depth. Highest abundances were at depths of 10-30 m during the day, and larger fish appeared to migrate from below 20 m to 0-10 m at night. There was evidence of multiple spawning locales and larval dispersal pathways that were depth- and area-specific. Northern rock sole larvae spawned west of Unimak Pass along the Aleutian Islands may be transported northward by the Bering Slope Current. Larvae spawned in the Gulf of Alaska and advected through Unimak Pass are differentially dispersed, primarily to the middle and outer shelves along the 100 m and 200 m isobaths, or along the Alaska Peninsula. Larvae spawned along the Alaska Peninsula east of Unimak Island appear to have the greatest chance of being transported to nursery areas in the coastal domain. Dispersal of near-surface northern rock sole larvae in any of these locations is likely influenced by wind-driven advection, but below-surface (>10 m) northern rock sole larval transport is probably more affected by factors that modulate geostrophic flow rather than wind-driven surface currents.     

胶州湾红岛码头疏浚物质输移扩散数值预测

利用有限元分步杂交法，首先对胶州湾海域潮流场进行了数值模拟，进而建立了胶州湾疏浚物悬浮泥沙的二维输运——扩散模型，并应用于胶州湾红岛拟建码头疏浚区的疏浚物输运扩散数值模拟预测，根据预测结果分析了红岛码头疏浚区施工期间悬浮泥沙对附近水环境的影响。