δ15N variation in Ulva lactuca as a proxy for anthropogenic nitrogen inputs in coastal areas of Gulf of Gaeta (Mediterranean Sea)

We tested the capacity of Ulva lactuca to mark N sources across large marine areas by measuring variation in its δ¹⁵N at several sites in the Gulf of Gaeta. Comparisons were made with the macroalga Cystoseira amentacea. Variation of δ¹⁵N values was assessed also in the coastal waters off the Circeo Natural Park, where U. lactuca and C. amentacea were harvested, as these waters are barely influenced by human activities and were used as reference site. A small fragment from each frond was preserved before deployment in order to characterize the initial isotopic values. After 48 h of submersion, U. lactuca was more responsive than C. amentacea to environmental variation and δ¹⁵N enrichment in the Gulf of Gaeta was observed. The spatial distribution of δ¹⁵N enrichment indicated that different macro-areas in the Gulf were affected by N inputs from different origins. Comparison of the δ¹⁵N values of fragments taken from the same transplanted frond avoided bias arising from natural isotopic variability.     

Concentration,composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar,Arabian Gulf

Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6 ng g⁻¹ to 1025 ng g⁻¹. The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe + Ant), (Flt/Flt + Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin.     

Anthropogenic lead concentrations and sources in Baltic Sea sediments based on lead isotopic composition

The Gulf of Gdańsk is influenced by heavy metals of anthropogenic origin. In this study, temporal concentration changes of Pb, Zn, Cd, and Cu were studied in six, 50 cm long sediment cores. The main aim of the study was to concentrate on the history of Pb fluxes and Pb isotopic composition (²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb) to trace Pb sources. The lowest Pb concentrations (19 μg g⁻¹) were measured in sediments deposited circa 1860, while the highest Pb concentrations (63–147 μg g⁻¹) were measured in sediments deposited between 1960s and 70s. Pre-industrial Pb fluxes were 7 Pb m² year⁻¹, while after WWII they reached 199 Pb m² year⁻¹. Highest ²⁰⁶Pb/²⁰⁷Pb ratios (∼1.22) were measured in the oldest sediment layers, and the lowest ²⁰⁶Pb/²⁰⁷Pb ratios (∼1.165) were measured in the sediments deposited in 1970s–90s. During the period of highest Pb contamination, the anthropogenic Pb fraction reached up to 93%. A general discussion of the Pb sources, emissions, and loads for Poland is included.     

渤海湾盆地"四扇一沟"沉积体系及其油气意义

阐述了渤海湾及其外围古近系有利于油气的沉积相的特点和分布,以及它们对油气分布的影响.沉积相受构造的影响很明显,形成的沉积体可以为油气的勘探提供有利的预测.沉积体系的划分应该概念明确,各分类之间不应有重叠之嫌.渤海湾地区的沉积体由冲积扇相、湖成三角洲相、扇三角洲相、湖底扇相、非扇沟道浊积岩相、滨湖-浅湖滩坝相、半深湖-深湖相(亚相)等组成.研究了各沉积体系的特点,并从生储盖的角度研究各体系的储层的特点.     

东濮凹陷古近系沙三段、沙四段介形类生物地层及界线

根据十余口探井微体古生物分析结果和对多年来积累的大量微体古生物分析资料的复查 ,将东濮凹陷古近系沙河街三段 (ES3)和四段 (ES4 )的介形类化石群自下而上分为 3个组合和 3个亚组合 :Cyprinotus igneus组合 ,分布于沙四段下亚段 ;Cyprinotus altilis- Cyprinotus jiyangensis组合 ,分布于沙四段上亚段 ;H uabeinia sinensis组合 ,分布于沙三段 ,其中 H uabeinia obscura- H uabeinia costatispinata亚组合分布于沙三段下亚段 ,H uabeiniasinensis- Candona binxianensis亚组合分布于沙三段中亚段 ,H uabeinia huidongensis- Cyprinotus dongmingensis亚组合分布于沙三段上亚段。各化石组合特征比较清楚 ,为东濮凹陷沙三段、沙四段的划分以及与渤海沿岸盆地的对比提供了依据。虽然东濮凹陷缺少渤海沿岸盆地沙四段顶界的标志性化石 Austrocypris,但该区沙三段、沙四段介形类化石组合整体面貌与整个渤海沿岸盆地相比仍然具有可对比性 ,从介形类化石组合方面来确定本区沙三段、沙四段的界线仍然是可行的     

Response of bedload transport, submarine topography, and dune internal structures to typhoon processes off Dongfang coast in the Beibu Gulf

Bedload sediment transport was estimated by the SEDTRANS96 model based on three-day hydrodynamics data obtained off the Dongfang coast in the Beibu Gulf during Typhoon Ketsana in September 2009. Bedforms on the sea floor off the Dongfang coast and internal structures of a typical dune were interpreted to evaluate storm influences on individual dunes and the dune field. Results indicated that flow forcings and related bedload transport were both strengthened significantly due to Typhoon Ketsana. The measurements and modeling results, which mainly included three different stages, presented noticeable phasic variation. The three stages were dominated by tidal current (Period Ⅰ), tidal current combined with wind-induced waves (Period Ⅱ), and swells combined with tidal current and seaward flows (Period Ⅲ). This phasic variation could be a common trait of hydrodynamics due to typhoons moving westwardly to the south of Hainan Island and Beibu Gulf in South China Sea. Results indicated that the maximum bedload transport rate for every burst in Period Ⅲ was almost 100 times larger than that in Period I and was ten times larger than that in Period II. However, the short-term increase in bedload transport induced by storms like Ketsana did not change the long-term evolution of dune morphology. Evidence was given by the internal structures of a typical dune, which revealed renewed modification under subsequent moderate conditions after storm erosion. Instead, storms may influence at different scales and regional allocation of sand dunes in some large areas because changes of the sea floor in large scales can hardly be recovered. More surveys during and after storm passage are also needed to document the level of positive contribution to forward migration.     

Geotechnical characterization of slump scars,eroded slopes,and correlated deposits on continental margins: Gulf of Lions,Western Mediterranean sea

Abstract

Vertical variations of geotechnical properties in the uppermost sediment layers characterize the main sedimentary processes acting on the construction and destruction of progressive‐type continental slopes. In the Gulf of Lions, the original thicknesses and distribution of the uppermost sedimentary layers of the continental slope and rise, which consist of Holocene muds overlying Pleistocene muds, have been greatly modified by erosion and several kinds of slope failure processes. Each process is typified through sets of geotechnical properties measured in the eroded or slumped sections and in the associated sediment accumulations.

In slump scars, the water‐rich Holocene muds lie on fine, overconsolidated, Pleistocene muds with high plasticity and low shear strength. In bottom current‐eroded slopes, where modern sedimentation is extremely reduced, the Pleistocene muds frequently outcrop and may sometimes be overlain by a very thin layer of Holocene muds. The Pleistocene muds of eroded slopes are overconsolidated and more silty and less plastic than the Pleistocene muds from slopes affected by slope failure, their shear strength being 10 times greater.

Deposits at the toe of slumps are very often formed by several superposed three‐layer units (triplets of interstratified Holocene, transitional, and Pleistocene layers) issued from retrogressive slumping occurring in the slump scars above their head area. The main body of each layer is then relatively undisturbed, showing the usual burial geotechnical gradients due to overburden pressure (i.e., decrease of water content and increase of unit weight and shear strength). At the toe of bottom current‐eroded slopes, a thick and homogeneous layer of Holocene muds overlies the Pleistocene muds; this Holocene layer has unappreciable burial depth gradient of its geotechnical parameters because of a high rate of modem and continuous deposition.     

The Hormuz Strait Dam Macroproject—21st Century Electricity Development Infrastructure Node (EDIN)?

ABSTRACT

Ocean gulfs offer a means of artificially creating a depression, which can be used for a regionally significant hydroelectric macroproject. We examine here the case for a dam at the Strait of Hormuz that blocks a large gulf situated in an arid region. A 35 m evaporation of this concentration basin will reduce its watery surface area by ～53% and allow generation of ～2.050 MW (or possibly ～2.500 MW) of electricity. Our conclusion is that the proposed Electricity Development Infrastructure Node (EDIN) is a feasible and desirable macroproject. If the macroproject starts in the near-term future, it would require a significant change in the logistics of oil and gas transport from this region. Alternatively, it can be considered as an attractive future solution for the energy requirements of the region after exhaustion of its oil and gas reserves.     

全球三大富油气前陆盆地油气分布特征对比

波斯湾盆地、东委内瑞拉盆地和西加盆地是全球油气最富集的前陆盆地。根据最新油气地质资料分析,它们的油气分布特征及资源结构存在明显差异。区域上,3个前陆盆地的逆冲褶皱带和前渊一斜坡带均有油气分布,但油气主要分布于前渊一斜坡带。层系上,波斯湾盆地91.0%以上的油气储量分布于被动陆缘层系,而东委内瑞拉盆地和西加盆地的油气则主要富集于前陆盆地层系。波斯湾盆地的油气资源以常规油气为主,而东委内瑞拉盆地和西加盆地则以非常规重油和天然沥青最为富集。区域性盖层与输导体系的配置关系是控制前陆盆地油气资源结构的主要因素。     

Tropical harmful algal blooms: An emerging threat to coral reef communities?

Tropical harmful algal blooms (HABs) are increasing in frequency and intensity and are substantially affecting marine communities. In October/November 2008 a large-scale HAB event (> 500 km², dinoflagellate Cochlodinium polykrikoides) in the Gulf of Oman caused the complete loss of the branching corals, Pocillopora and Acropora spp., and substantial reductions in the abundance, richness and trophic diversity of the associated coral reef fish communities. Although the causative agents of this C. polykrikoides bloom are unknown, increased coastal enrichment, natural oceanographic mechanisms, and the recent expansion of this species within ballast water discharge are expected to be the main agents. With rapid changes in oceanic climate, enhanced coastal eutrophication and increased global distribution of HAB species within ballast water, large-scale HAB events are predicted to increase dramatically in both intensity and distribution and can be expected to have increasingly negative effects on coral reef communities globally.