Inside-sediment partitioning of PAH, PCB and organochlorine compounds and inferences on sampling and normalization methods

Comparability of sediment analyses for semivolatile organic substances is still low. Neither screening of the sediments nor organic-carbon based normalization is sufficient to obtain comparable results. We are showing the interdependency of grain-size effects with inside-sediment organic-matter distribution for PAH, PCB and organochlorine compounds. Surface sediment samples collected by Van-Veen grab were sieved and analyzed for 16 PAH, 6 PCB and 18 organochlorine pesticides (OCP) as well as organic-matter content. Since bulk concentrations are influenced by grain-size effects themselves, we used a novel normalization method based on the sum of concentrations in the separate grain-size fractions of the sediments. By calculating relative normalized concentrations, it was possible to clearly show underlying mechanisms throughout a heterogeneous set of samples. Furthermore, we were able to show that, for comparability, screening at <125 μm is best suited and can be further improved by additional organic-carbon normalization.     

Partitioning behaviour of perfluorinated alkyl contaminants between water, sediment and fish in the Orge River (nearby Paris, France)

This paper reports on the partitioning behaviour of 15 perfluorinated compounds (PFCs), including C₄-C₁₀ sulfonates and C₅-C₁₄ carboxylic acids, between water, sediment and fish (European chub, Leuciscus cephalus) in the Orge River (nearby Paris). Total PFC levels were 73.0 ± 3.0 ng L⁻¹ in water and 8.4 ± 0.5 ng g⁻¹ in sediment. They were in the range 43.1-4997.2 ng g⁻¹ in fish, in which PFC tissue distribution followed the order plasma > liver > gills > gonads > muscle. Sediment-water distribution coefficients (log K_d) and bioaccumulation factors (log BAF) were in the range 0.8-4.3 and 0.9-6.7, respectively. Both distribution coefficients positively correlated with perfluoroalkyl chain length. Field-based biota-sediment accumulation factors (BSAFs) are also reported, for the first time for PFCs other than perfluorooctane sulfonate. log BSAF ranged between −1.3 and 1.5 and was negatively correlated with the perfluoroalkyl chain length in the case of carboxylic acids.     

流域经济增长空间分异研究——基于2001～2009年长江流域数据的面板计量分析

流域经济是以水系为轴线的区域经济,其发展状况对国民经济有重要影响,其研究为区域开发提供新视角。在理论方法上,根据内生经济增长理论,采用柯布 道格拉斯生产函数,构建一个包括技术进步、物质资本和人力资本作为内生要素的流域经济增长框架。在实践论证上,以长江为样本域,运用面板计量分析方法,测度生产要素对流域上中下游经济增长的影响。结果显示：不同生产要素对流域经济不同域段作用强度不同,且呈现出明显的梯度效应,即沿江而下,技术进步和人力资本对经济增长的贡献度逐渐加大,物质资本则恰好相反。在此基础上,提出缩小流域经济的不平衡程度的政策建议,主要包括促使流域上游地区人力资本开发、实施流域大开发战略和推进流域城市化等     

雅砻江流域湿地景观格局变化分析

应用ArcGIS软件,对雅砻江流域湿地1986和2000年遥感数据进行解译、矢量化处理,用Apack软件进行湿地景观格局指数计算,研究了近15 a雅砻江流域景观空间格局特征及其变化。结果表明：（1）近15 a雅砻江流域湿地景观面积减少,减少量为49404 hm2,占2000年湿地总面积的0506%;（2）两个时期内湿地斑块密度保持不变,湿地景观的聚集度都很高,均在099以上,湿地景观集中分布,破碎化水平低;（3）雅砻江流域湿地景观的多样性指数水平和均匀度水平较低,而且两指数在两个个时期内没有发生太大的变化,且各类湿地景观比例差异相对较大,沼泽湿地景观控制的程度较高;（4）雅砻江流域的5类湿地景观分布质心基本上未发生变化,但总体格局分布质心向南偏移001°,再向西偏移023°,整体上向西南方向偏移了2532 km     

基于用水总量控制的水资源承载能力分析研究——以赣江袁河流域为例

通过界定水资源承载能力的概念和内涵,提出基于总量控制条件下人口 经济 水资源三者系统协调耦合的水资源承载能力分析计算方法,分别采用产业结构调整和水资源优化配置模型等措施,以赣江袁河流域水资源承载能力分析计算进行例证。研究结果表明：在用水总量控制、保障社会发展水平和人均GDP水平条件下,（1）优化后行业用水定额下降,流域需水总量减少,水资源利用效率提高,目标年2015年和2030年流域需水量调整后较调整前分别减少036亿m3、090亿m3,较调整前下降了23%和53%;（2）对于不同目标年,优化后用水区域可承载GDP和承载人口有所增加,2015年和2030年全流域可承载GDP分别增加2649亿元和15191亿元,全流域可承载人口分别增加773万人和1874万人     

高速铁路影响下的长三角城市群可达性空间格局演变

交通网络体系对城市群空间结构的优化有重要作用,随着“高铁时代”的到来,长三角城市群区域空间结构也将发生深远的变化。引入可达性的概念,以现状2010年与规划2020年的长三角综合交通设施网络为基础,选取长三角各城市之间加权平均最短旅行时间为度量指标,分析了高速铁路系统的发展对长三角区域空间格局未来演化的影响,揭示了高速铁路将全面提升长三角区域可达性水平,大大缩短城市之间的时空距离,推动长三角一体化发展,并通过都市圈、经济轴带的形成与发展,促进区域均衡化空间结构的形成。另一方面,虽然高速铁路将推动多中心空间结构的形成,但对城市可达性水平的影响具有明显的区域差异,城市在新的高铁格局下应探析符合自身特点的发展战略     

混凝土大坝震害评估模型的研究及对黄河上游大坝的分析

利用前人所编的历代(共四代)地震烈度(地震动)区划图,组合叠加后得到一个综合烈度(地震动)。这种叠加是一个集成的专家系统综合认识结果,以此作为坝体可能遭受地震破坏危险的因素。初步研究建立了混凝土大坝震害评估模型,此模型是考虑了坝体的结构类型、建设年代、使用现状、场地条件、抗震设防水平等因素,用逐步线性拟合方法进行回归分析得到的。用此模型对汶川地震破坏的坝体进行了实例分析,分析结果比较符合实际。最后,用这个模型对黄河上游10座重点混凝土大坝做了震害评估分析。     

Cs, Pu concentrations and the Pu/Pu atom ratio in a sediment core from the sub-aqueous delta of Yangtze River estuary

A sediment core collected from the sub-aqueous delta of the Yangtze River estuary was subjected to analyses of ¹³⁷Cs and plutonium (Pu) isotopes. The ¹³⁷Cs was measured using γ-spectrometry at the laboratories at the Nanjing University and Pu isotopes were determined with Accelerator Mass Spectrometry (AMS), measurements made at the Australian National University. The results show considerable structure in the depth concentration profiles of the ¹³⁷Cs and ^239+240Pu. The shape of the vertical ¹³⁷Cs distribution in the sediment core was similar to that of the Pu. The maximum ¹³⁷Cs and ^239+240Pu concentrations were 16.21 ± 0.95 mBq/g and 0.716 ± 0.030 mBq/g, respectively, and appear at same depth. The average ²⁴⁰Pu/²³⁹Pu atom ratio was 0.238 ± 0.007 in the sediment core, slightly higher than the average global fallout value. The changes in the ²⁴⁰Pu/²³⁹Pu atom ratios in the sediment core indicate the presence of at least two different Pu sources, i.e., global fallout and another source, most likely close-in fallout from the Pacific Proving Grounds (PPG) in the Marshall Islands, and suggest the possibility that Pu isotopes are useful as a geochronological tool for coastal sediment studies. The ¹³⁷Cs and ^239+240Pu inventories were estimated to be 7100 ± 1200 Bq/m² and 407 ± 27 Bq/m², respectively. Approximately 40% of the ^239+240Pu inventory originated from the PPG close-in fallout and about 50% has derived from land-origin global fallout transported to the estuary by the river. This study confirms that AMS is a useful tool to measure ²⁴⁰Pu/²³⁹Pu atom ratio and can provide valuable information on sedimentary processes in the coastal environment.     

Plutonium isotopes concentration in seawater and bottom sediment off the Pacific coast of Aomori sea area during 1991-2005

A radioactivity survey was launched in 1991 to determine the background levels of ^239+240Pu in the marine environment off a commercial spent nuclear fuel reprocessing plant before full operation of the facility. Particular attention was focused on the ²⁴⁰Pu/²³⁹Pu atom ratio in seawater and bottom sediment to identify the origins of Pu isotopes. The concentration of ^239+240Pu was almost uniform in surface water, decreasing slowly over time. Conversely, the ^239+240Pu concentration varied markedly in the bottom water and was dependent upon the sampling point, with higher concentrations of ^239+240Pu observed in the bottom water sample at sampling points having greater depth. The ²⁴⁰Pu/²³⁹Pu atom ratio in the seawater and sediment samples was higher than that of global fallout Pu, and comparable with the data in the other sea area around Japan which has likely been affected by close-in fallout Pu originating from the Pacific Proving Grounds. The ²⁴⁰Pu/²³⁹Pu atom ratio in bottom sediment samples decreased with sea depth. The land-originated Pu is not considered as the reason of the increasing ^239+240Pu concentration and also decreasing the ²⁴⁰Pu/²³⁹Pu atom ratio with sea depth, and further study is required to clarify it.     

Estimating sediment and caesium-137 fluxes in the Ribble Estuary through time-series airborne remote sensing

High spatial and temporal resolution airborne imagery were acquired for the Ribble Estuary, North West England in 1997 and 2003, to assess the application of time-series airborne remote sensing to quantify total suspended sediment and radionuclide fluxes during a flood and ebb tide sequence. Concomitant measurements of suspended particulate matter (SPM) and water column turbidity were obtained during the time-series image acquisition for the flood and ebb tide sequence on the 17th July 2003 to verify the assumption of a vertically well mixed estuary and thus justifying the vertical extrapolation of spatially integrated estimate of surface SPM. The ¹³⁷Cs activity concentrations were calculated from a relatively stable relationship between SPM and ¹³⁷Cs for the Ribble Estuary. Total estuary wide budgets of sediment and ¹³⁷Cs were obtained by combining the image-derived estimates of surface SPM and ¹³⁷Cs with estimates of water volume from a two-dimensional hydrodynamic model (VERSE) developed for the Ribble Estuary. These indicate that around 10,000 tonnes of sediment and 2.72 GBq of ¹³⁷Cs were deposited over the tidal sequence monitored in July 2003. This compared favourably with bed height elevation change estimated from field work. An uncertainty analysis on the total sediment and ¹³⁷Cs flux yielded a total budget of the order of 40% on the final estimate. The results represent a novel approach to providing a spatially integrated estimate of the total net sediment and radionuclide flux in an intertidal environment over a flood and ebb tide sequence.