The Eurobulker oil spill: mid-term changes of some ecosystem indicators

The sinking of the tanker Eurobulker in Southern Evoikos gulf (Aegean Sea, Greece) in September 2000 resulted in a spill of 700 tons of crude oil. The environmental impact of the spill was studied by the National Centre for Marine Research. The hydrocarbon concentrations in water, sediment and coastal benthic organisms were measured and the response of the benthic communities to the disturbance caused by the oil spill was studied along the direction to the coast and over three sampling seasons. The most severe and direct effects were evidenced on the muddy benthic communities of the accident site and the stations in the close vicinity sampled shortly after the spill. The effects included reduction of the species richness and community diversity, but the communities reached full recovery 8 months later. The impact of the spill was more indirect and delayed in the coastal stations, where as the hydrocarbon measurements indicated, the pollutants were transported later and induced their effects on the benthic communities 6 months after the accident.     

Visualization of spatial patterns and temporal trends for aerial surveillance of illegal oil discharges in western Canadian marine waters

This paper examines the use of exploratory spatial analysis for identifying hotspots of shipping-based oil pollution in the Pacific Region of Canada’s Exclusive Economic Zone. It makes use of data collected from fiscal years 1997/1998 to 2005/2006 by the National Aerial Surveillance Program, the primary tool for monitoring and enforcing the provisions imposed by MARPOL 73/78. First, we present oil spill data as points in a “dot map” relative to coastlines, harbors and the aerial surveillance distribution. Then, we explore the intensity of oil spill events using the Quadrat Count method, and the Kernel Density Estimation methods with both fixed and adaptive bandwidths. We found that oil spill hotspots where more clearly defined using Kernel Density Estimation with an adaptive bandwidth, probably because of the “clustered” distribution of oil spill occurrences. Finally, we discuss the importance of standardizing oil spill data by controlling for surveillance effort to provide a better understanding of the distribution of illegal oil spills, and how these results can ultimately benefit a monitoring program.     

Weathering of Oil in a Surficial Aquifer

The composition of crude oil in a surficial aquifer was determined in two locations at the Bemidji, MN, spill site. The abundances of 71 individual hydrocarbons varied within 16 locations sampled. Little depletion of these hydrocarbons (relative to the pipeline oil) occurred in the first 10 years after the spill, whereas losses of 25% to 85% of the total measured hydrocarbons occurred after 30 years. The C_6‐30 n‐alkanes, toluene, and o‐xylene were the most depleted hydrocarbons. Some hydrocarbons, such as the n‐C_10–24 cyclohexanes, tri‐ and tetra‐ methylbenzenes, acyclic isoprenoids, and naphthalenes were the least depleted. Benzene was detected at every sampling location 30 years after the spill. Degradation of the oil led to increases in the percent organic carbon and in the δ ¹³C of the oil. Another method of determining hydrocarbon loss was by normalizing the total measured hydrocarbon concentrations to that of the most conservative analytes. This method indicated that the total measured hydrocarbons were depleted by 47% to 77% and loss of the oil mass over 30 years was 18% to 31%. Differences in hydrocarbon depletion were related to the depth of the oil in the aquifer, local topography, amount of recharge reaching the oil, availability of electron acceptors, and the presence of less permeable soils above the oil. The results from this study indicate that once crude oil has been in the subsurface for a number of years there is no longer a “starting oil concentration” that can be used to understand processes that affect its fate and the transport of hydrocarbons in groundwater.     

2020年7月12日唐山MS5.1地震前通州台井下地电阻率变化

通州地震台井下地电阻率观测于2019年11月完成建设,完成相关测试后于2020年投入实际观测。在2020年7月12日河北唐山M_S5.1地震前,地电阻率呈现出一定的变化,约从4月上旬开始NE和NW测道同步出现下降变化,6月中旬开始NW测道出现转折回升。EW测道同期存在一定的上升变化,但变化幅度约为NE测道幅度的1/4。此次地震的震源机制解为走滑型,最大主压应力方位为101°,与NE、NW和EW测道的夹角分别为70°、50°和10°。震前NE测道下降幅度最大,NW测道次之,EW测道变化幅度最小,符合实验结果和地震前地电阻率各向异性变化特征。     

Risk assessment and national measure plan for oil and HNS spill accidents near Korea

Many oil and HNS spill accidents occur in the waters surrounding the Korean Peninsula because Korea is one of the biggest trading partners in the world. In this study, we analyzed the oil and HNS spill accidents that occurred between 1994 and 2005 and created risk matrices to assess these accidents. The worst scenarios of future oil and HNS spill accidents were established, and the maximum spill amounts were estimated using historic accident data and a correlation from IPIECA. The maximum spill amounts are estimated to be between 77,000 and 10,000 tons of oil and HNS, respectively. One third of the spill materials should be removed using recovery equipment within three days of the spill event, according to the national measure plan. The capability of recovery equipment to remove spill materials can be estimated, and the equipment should then be prepared to mitigate the harmful effects of future oil and HNS accidents on humans and marine ecosystems.     

利用中国地震科学台阵研究青藏高原东南缘地壳各向异性:第一期观测资料的剪切波分裂特征

中国地震科学台阵第一期(2011—2013年)布设在南北地震带南段,本研究利用中国地震科学台阵布设在云南及相邻地区的部分流动台站记录到的2011年6月至2013年3月的数字地震波形资料,开展地壳各向异性分析.本文使用剪切波分裂系统分析方法(SAM方法),获得了研究区内67个台站的剪切波分裂参数.研究结果表明,受到云南及周边地区复杂的构造、应力环境和纵横交错的断裂分布的影响,该地区快剪切波偏振方向(PAZ)整体上显示出NNE向和NE向的优势取向,但在空间分布上比较复杂,虽然大部分台站的PAZ与构造应力场方向一致,但部分断裂附近台站的PAZ受到断裂的影响.结果显示,本研究区内不同区域的PAZ有一定差异性.本研究划分了5个子区,西部3个不同区域的PAZ从北到南分别为NNW向、近N-S向和NE向,有顺时针旋转的趋势,而东部的2个区域PAZ分别为NEE向和NNW向.研究证实,青藏东南缘地区的地壳各向异性空间分布虽然非常复杂,但大体上与区域内的主压应力的方向和断裂分布相关.     

首都圈地区横波分裂与地壳应力场特征

利用宽频带流动地震台阵和首都圈固定台网记录到的近震波形数据,研究了首都圈地区（386°N～410°N,〖JP〗1150°E～1197°E）的横波分裂,给出了快波偏振优势方向的场分布,讨论了首都圈地区的应力场特征. 在此基础上,采用二维线弹性有限元数值模拟方法,探讨了断层不均匀滑动对区域构造应力场的影响. 结果表明：（1）首都圈地区的应力场整体特征表现为NE向的背景应力场和受张家口-蓬莱断裂带控制的NW向的局部应力场;（2）在研究区域的西半部分和中部,最大主压应力方向为NE60°～70°,在唐山大震区及其东部区域,最大主压应力方向近WE向;（3）首都圈地区的局部应力场最大主压应力方向比较一致,基本上都与张家口-蓬莱断裂带走向平行,为120°～130°;〖JP2〗（4）首都圈区域内断层的存在及其郴均匀滑动是研究区内出现大量局部应力场的一个重要原因,张家口-〖JP〗蓬莱断裂带对首都圈局部应力场起着重要的控制作用.      

Relationship Between Oil Exposure and Reproductive Parameters in Fish Collected Following the Exxon Valdez Oil Spill

Following the Exxon Valdez oil spill (EVOS) in 1989, the effect of oil exposure on reproductive parameters was investigated in wild populations of female dolly varden, yellowfin sole, and pollock. Exposure to oil was the highest in the first year of sampling and decreased in the subsequent years of sampling. Both positive and negative correlations between reproductive parameters and indices of exposure were detected in varying degrees for all three species. Reproductive parameters were not measured in the first year of sampling. For those parameters found to be significantly correlated to oil exposure, an exponential regression function was used to project reproductive parameters of fish sampled in the first year of the spill. A higher proportion of dolly varden sampled in 1989 were projected to have depressed plasma estradiol-17β compared to the fish sampled in 1990.     

Results from a sixteen year study on the effects of oiling from the Exxon Valdez on adult pink salmon returns

For sixteen years following the 1989 Exxon Valdez oil spill adult returns of pink salmon in Prince William Sound, Alaska were monitored to assess spill effects on survival. No evidence of spill effects was detected for either intertidal or whole-stream spawning fish. From 1989 through 2004 mean densities for oiled and reference streams tracked each other, illustrating similar responses of oiled and reference stream adult populations to naturally changing oceanographic and climactic conditions. Hatchery fish strayed into the study streams, but similar incursions occurred in oiled and reference streams, and their presence was compensated for to eliminate their influence on determining the success of the returning natural populations. These results, showing no detectable effects of oiling on pink salmon spawning populations, are supported by published field studies on pink salmon incubation success in oiled streams.     

Degradation rates of low molecular weight PAH correlate with sediment TOC in marine subtidal sediments

The degradation rate of low molecular weight (LMW) polycyclic aromatic hydrocarbons (PAH) in subtidal marine sediments was found to correlate with sediment total organic carbon (TOC) in stations sampled two or more times after the North Cape No. 2 fuel oil spill. With 2.5-5 months between samplings, stations with lower sediment TOC had lower fractions of LMW PAH remaining at the time of the second sampling. Apparent first-order degradation rate constants calculated for each station varied by nearly an order of magnitude between stations with a range of TOC from 0.4% to 7.3%. The correlation of degradation rate with sediment TOC can be used to provide improved and site-specific predictions of the initial time-course of LMW PAH concentrations in sediments after oil spills.     

四川宜宾地区S波分裂特征

本文采用纵横比与偏振分析相结合的方法测定了2013年4月25日~2015年12月31日四川宜宾地区10个台站S波分裂参数,即快波偏振方向和慢波延迟时间。结果表明,华蓥山断裂两侧台站呈现不同的快波偏振优势方向,断裂带以西的台站偏振优势方向为NW向,与区域应力场方向一致;位于断裂带以东的台站优势偏振方向为NE向,与断裂走向一致。在地震密集分布区域内的CNI台的优势偏振方向为NE向,与台站附近的断裂带走向基本一致。研究区域南段的3个台站(JLI、YAJ、XWE)优势偏振方向近NS向。各个台站平均慢波延迟时间在3.07~11.95ms/km范围内,慢波延迟时间最大的台站是CNI台,距离2013年4月25日06时10分M_L5.2地震震中位置最近,这反映出震源区地震波各向异性程度较强。CNI台站的慢波延迟时间显示,在2015年2月7日M_L4.8地震前观测到慢波延迟时间有明显的上升趋势。     

乌鲁木齐及附近地区剪切波分裂特征研究

利用S波分裂的方法，分析了2003年2月14日新疆石河子5．4级地震前后多台所记录的小地震的S波分裂特征，发现震源附近地区的S波分裂特征对中强震仍有一定的前兆意义．震中附近的3个地震台记录的S波偏振方向在5．4级地震前出现由原来与区域应力场一致的NE向转为NW向震后又转回NE向。5．4级地震前各台记录的慢波延迟时间总体表现出由小变大的特征．     

2010 oil spill: trajectory projections based on ensemble drifter analyses

An accurate method for long-term (weeks to months) projections of oil spill trajectories based on multi-year ensemble analyses of simulated surface and subsurface (z = −800 m) drifters released at the northern Gulf of Mexico spill site is demonstrated during the 2010 oil spill. The simulation compares well with satellite images of the actual oil spill which show that the surface spread of oil was mainly confined to the northern shelf and slope of the Gulf of Mexico, with some (more limited) spreading over the north/northeastern face of the Loop Current, as well as northwestward toward the Louisiana–Texas shelf. At subsurface, the ensemble projection shows drifters spreading south/southwestward, and this tendency agrees well with ADCP current measurements near the spill site during the months of May–July, which also show southward mean currents. An additional model analysis during the spill period (Apr–Jul/2010) confirms the above ensemble projection. The 2010 analysis confirms that the reason for the surface oil spread to be predominantly confined to the northern Gulf shelf and slope is because the 2010 wind was more southerly compared to climatology and also because a cyclone existed north of the Loop Current which moreover was positioned to the south of the spilled site.     

Short-term effects of the prestige oil spill on the peregrine falcon (Falco peregrinus)

We have monitored the distribution, population status, breeding success, turnover rate and diet of a Peregrine Falcon population in Bizkaia (North of Spain) since 1997. On the 13th November 2002, the tanker Prestige sunk off La Coruña (NW Spain) causing an oil spill that affected the whole of the Cantabrian Coast and the Southwest of France. The total number of birds affected by the Prestige oil spill was expected to be between 115,000 and 230,000, some of them raptors. The loss of clutches during the incubation period increased significantly and was correlated with the loss of females. Moreover, the turnover rate of the population increased from 21% to 30%. The polycyclic aromatic hydrocarbon concentrations in the eggs, collected from five nests after they were deserted, ranged from 21.20 ng/g to 461.08 ng/g, values which are high enough to cause the death of the embryos and poisoning of adult birds. The effects of pollution reached inland since some inland-breeding falcons prey on shorebirds that use rivers during their migratory flights. As the Prestige oil spill has clearly resulted in increased rates of adult mortality and reduced fertility, we suggest that the environmental authorities urgently undertake measures aimed at protecting the Peregrine Falcon in Bizkaia.     

2020年和林格尔ML4.5地震微震匹配定位及发震构造探讨

内蒙古和林格尔地处鄂尔多斯块体北缘阴山地震带内,历史上6级以上强震频发.2020年3月30日和林格尔发生ML4.5地震,打破了自2005年以来阴山地震带ML4.0以上地震的长期平静.研究此次地震序列的发震构造对区域应力状态和地震危险性分析有重要作用,然而内蒙古地震台网台站较为稀疏,相对于华北其他地区地震监测能力较低,对...     

Scientific management of Mediterranean coastal zone: a hybrid ocean forecasting system for oil spill and search and rescue operations

The oil spill from Prestige tanker showed the importance of scientifically based protocols to minimize the impacts on the environment. In this work, we describe a new forecasting system to predict oil spill trajectories and their potential impacts on the coastal zone. The system is formed of three main interconnected modules that address different capabilities: (1) an operational circulation sub-system that includes nested models at different scales, data collection with near-real time assimilation, new tools for initialization or assimilation based on genetic algorithms and feature-oriented strategic sampling; (2) an oil spill coastal sub-system that allows simulation of the trajectories and fate of spilled oil together with evaluation of coastal zone vulnerability using environmental sensitivity indexes; (3) a risk management sub-system for decision support based on GIS technology. The system is applied to the Mediterranean Sea where surface currents are highly variable in space and time, and interactions between local, sub-basin and basin scale increase the non-linear interactions effects which need to be adequately resolved at each one of the intervening scales. Besides the Mediterranean Sea is a complex reduced scale ocean representing a real scientific and technological challenge for operational oceanography and particularly for oil spill response and search and rescue operations.     

Spatial distribution and ecotoxicity of petroleum hydrocarbons in sediments from the Galicia continental shelf (NW Spain) after the Prestige oil spill

The distribution of aliphatic and aromatic hydrocarbons was determined in surface sediments collected at 36 stations along the Galicia continental shelf (NW Spain), following the Prestige oil spill. Sampling was performed in December 2002, just after the accident, and in February and September 2003. Concentrations of PAHs (summation operator 13 parent components) were in the range of 0.9-422 microg/kgdw, the highest values being close to coastal urban areas (e.g. Pontevedra and A Coru?a), whereas in the stations of the area most heavily impacted by the spill (off Costa da Morte) concentrations were in the range of 14.8-89.6 microg/kgdw, with a certain predominance of alkylated compounds, which may suggest a mixture of petrogenic and pyrolytic sources. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes) showed the occurrence of an old (weathered) petrogenic chronic pollution in the shelf sediments but not of the Prestige oil, with the possible exception of few stations in the area of Costa da Morte. This was attributed to the heavy nature of the spilled oil that was barely dispersed in the water column and mainly stranded on the coast or sedimented in the form of oil patches. The addition of increasing amounts of fuel oil to a representative sediment sample showed that the molecular indices were indicative of the presence of the Prestige oil when the amount was above 1g/kg of sediment. The toxicity of selected samples (showing the higher PAH concentrations) was tested using the bivalve embryogenesis bioassay. Embryogenesis success reached high values in all cases (80-88%, with 86% in the control), indicating a lack of toxicity in the sediments and supporting the conclusion that the patchiness of the fuel eventually reaching the seafloor reduced its impact on the benthic communities of the Galician shelf.     

四川紫坪铺水库库区地震剪切波分裂研究

本研究利用四川紫坪铺水库数字地震台网2004年8月17日~2008年5月11日的地震观测波形资料,使用剪切波分裂SAM系统分析方法,获得了四川紫坪铺水库库区8个数字地震台站的快剪切波偏振结果.结果表明,紫坪铺库区台站的快剪切波偏振优势方向主要为NE或NW方向;台站的快剪切波偏振优势方向与区域主压应力方向或活动断裂走向一致;快剪切波偏振方向变化可能与汶川大地震前区域应力场的增加和龙门山断裂带微破裂增加有关,慢剪切波时间延迟的变化与四川紫坪铺水库水位升降变化相关.     

海丰震群发震构造型式的讨论

海丰震区发育着规模宏大的 NE 向海丰——梅陇断裂及一系列与其平行的次级断裂.同时,还存在与其共轭的断续分布的 NW 向断裂.震群中的三个子群的主震的震源机制解非常类似,其中一节面为 NE,另一节面为 NW.从余震的空间分布及极震区的长轴方向来看,2月26日 ML3.3和4月9日 MLL,4.2地震的断层面为 NE 向;而3月14日 ML,3.4地震,其断层面应取 NW 向.又据137个小震的四个台的 P 波初动符号的组合特征,可划分为八个类型并作出相应的迭加震源机制解.综上所述,本区破裂过程,主震及Ⅰ、Ⅳ 类地震是岩块沿NE 及 NW 向共轭构造的粘滑;Ⅱ——Ⅴ、Ⅶ、Ⅷ 类地震是岩块在粘滑过程中对前后邻接岩块引起平行滑动方向的挤压(前)和引张(后)的转换应力场所产生的剪切破裂.