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.     

Trends in chronic marine oil pollution in Danish waters assessed using 22 years of beached bird surveys

Beached bird surveys provide an important tool for monitoring the level of oil pollution at sea, which is the most significant observable cause of death for a large number of waterbird species and pose a serious threat to wintering seabird populations. Linear regression analyses of oil rates from the Danish 22 year dataset show a decline in the oil pollution level in offshore areas of the eastern North Sea and Skagerrak and in near-shore parts of the Kattegat; but a worsening in the offshore areas of the Kattegat. These results raise concern for species such as common scoter, velvet scoter, eider and razorbill, for which the Kattegat serves as a globally important wintering area. It is recommended that surveillance for oil spills is intensified in inner Danish waters, and that action is taken to make responses towards offenders faster, and penalties for oil seepage higher.     

Echinoderms and oil pollution: A potential stress assay using bacterial symbionts

Oil pollution is a problem in the North Sea. Important sources of oil pollution are spills and drill cutting. Echinoderms are a major component of the macrobenthos in the North Sea (and elsewhere). They tend to be very sensitive to various types of marine pollution. Many species of echinoderms contain symbiotic sub-cuticular bacteria (SCB). The response of Amphiura filiformis, A. chiajei and Ophiothrix fragilis, all of which contain SCB, to oil pollution was studied in laboratory experiments, mesocosms and in the field. Sublethal stress was monitored by examining changes in the tissue loading of SCB. When subjected to hydrocarbon insult, there was a decline in the number of SCB. The potential use of SCB abundance to detect sublethal stress is discussed.     

Integrated environmental management: The Dutch Governmental view

In the last 10 years concern for the economic and ecological value of the North Sea has increased. Many different users are putting increasing pressure on the resources of the North Sea and its adjacent estuaries. Its uses include shipping, fisheries, the oil and gas industry, mineral extraction, and—along its shores—recreation. The North Sea suffers pollution directly from some of these sources, but also indirectly from discharges from land, from rivers and from the atmosphere. The resilience of the North Sea ecosystem puts limits on the human use. These limits have in a number of cases been exceeded. It is necessary to define and assess the sustainable use of the North Sea ecosystem. The sustainable use may be defined as the long-term use of current and future potential while ensuring sustainable conservation of the ecological value of the North Sea and adjacent vulnerable water systems. Integrated environmental management for the North Sea implies that policy-makers assess all interests and resolve any conflicts which arise. This paper considers the problem of input of organic substances into the North Sea. It considers a target scenario of sustainable use and ecological health, in relation to what concentrations of organic substances are permissible. Secondly, it considers a target percentage reduction in current inputs. Thirdly, it is necessary to give the measures to be taken to deal with the major sources of the pollution, i.e. to define target groups. Finally, the paper gives examples of the statutory instruments available to implement the chosen policy.     

Twenty years of Belgian North Sea aerial surveillance: a quantitative analysis of results confirms effectiveness of international oil pollution legislation

Over the years many policy measures have been taken to prevent illegal oil discharges from ships, like the MARPOL 73/78 Convention (1983) and the Bonn Agreement (1969/1983). However, the number of discharges remained high, leading to chronic oiling of seabirds and sensitive coastlines, therefore further measures were taken. The aim of this study is to quantify the effectiveness of two key legislative regulations: the IMO-designation of the North Sea as MARPOL Special Area which took effect in 1999, and the adoption of the EU Directive on Port Reception Facilities in 2000. Under study is the heavily navigated Belgian Surveillance Area, monitored since 1991, characterised by shallow waters with ecologically important sandbanks. The aerial surveillance data from 1991 to 2010 show a stepwise decrease in ship-source oil pollution. Three time periods can be distinguished with two turning points coinciding with the actual implementation of these key legislative measures, confirming their effectiveness.     

Towards an operational use of space imagery for oil pollution monitoring in the Mediterranean basin: a demonstration in the Adriatic Sea

Studies of operational pollution carried out by European commission - Joint Research Centre in the Mediterranean Sea for the years 1999-2004 are briefly introduced. The specific analysis of the Adriatic Sea for the same period demonstrates that this area has been characterized by a relevant number of illegal discharges from ships. After setting the historical background of the project AESOP (aerial and satellite surveillance of operational pollution in the Adriatic Sea), the content, partners and aim of the project are presented. Finally, the results of the first phase of the AESOP project are presented. The results seem very encouraging. For the first time in the Adriatic, real time detection of oil spills in satellite images and an immediate verification by the Coast Guard has been undertaken. An exploratory activity has also been carried out in collaboration with the University of Ljubljana to use automatic information system (AIS) to identify the ships detected in the satellite images.     

The use of chemical dispersants to combat oil spills at sea: A review of practice and research needs in Europe

In order to better understand the practice of dispersant use, a review has been undertaken of marine oil spills over a 10 year period (1995-2005), looking in particular at variations between different regions and oil-types. This viewpoint presents and analyses the review data and examines a range of dispersant use policies. The paper also discusses the need for a reasoned approach to dispersant use and introduces past cases and studies to highlight lessons learned over the past ten years, focussing on dispersant effectiveness and monitoring; toxicity and environmental effects; the use of dispersants in low salinity waters; response planning and future research needs.     

Oil spill treatment products approval: the UK approach and potential application to the Gulf region

The environmental threat from oil spills remains significant across the globe and particularly in regions of high oil production and transport such as the Gulf. The ultimate damage caused can be limited by mitigation actions that responders deploy. The responsible and appropriate use of oil spill treatment products (e.g. dispersants, sorbents etc.) can offer response options that can result in substantial net environmental benefit. However, the approval and choice of what products to use needs careful consideration. The United Kingdom has had in place a statutory approval scheme for oil spill treatment products for 30 years. It is based on measures of efficiency and environmental acceptability. Two toxicity tests form an integral part of the assessment, the Sea test and the Rocky Shore test, and work on the premise that approved products will not make the situation significantly worse when added to spilled oil. This paper outlines the UK approach and how its rationale might be applied to the approval of products specific for the Gulf region. Issues such as species choice, higher temperatures and salinity and regional environmental conditions are considered.     

Characterization of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) in tar-balls collected from the East Coast of Peninsular Malaysia

The East Coast of Peninsular Malaysia faces the South China Sea and is vulnerable to oil pollution because of intense petroleum production activities in the area. The South China Sea is also a favored route for supertankers carrying crude oil to the Far East. Consequently, oil spills can occur, causing pollution and contamination in the surrounding areas. Residual oil spills stranded on coastal beaches usually end up as tar-balls. Elucidating the sources of tar-balls using a molecular marker approach is essential in assessing environmental impacts and perhaps settling legal liabilities for affected parties. This study utilizes a multimodal molecular marker approach through the use of diagnostic ratios of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) to determine the source, distribution and weathering of tar-balls. Hopane ratios (e.g., C29/C30, and summation C31-C35/C30 ratios) were used to identify the sources of tar-balls. The weathering effects were distinguished by using alkanes, namely the unresolved complex mixture (UCM) and low molecular weight/high molecular weight (L/H) ratios. Similarly, PAHs were also used for the determination of weathering processes undergone by the tar-balls. This multimodal molecular marker gave a very strong indication of the sources of tar-balls in this study. For example, 16 out of 17 samples originated from South East Asian Crude Oil (SEACO) with one sample from Merang, Terengganu originating from North Sea Oil (Troll). The TRME-2 sample may have come from a supertanker's ballast water discharge. The second possibility is that the tar-ball may have been transported via oceanographic currents. All 'weathered' sample characterizations were based on the presence of UCM and other ratios. The multimodal molecular marker approach applied in this study has enabled us to partially understand the transport behavior of tar-balls in the marine environment and has revealed insights into the weathering process of tar-balls.     

南黄海和东海地区现代构造应力场特征的研究

分析研究了南黄海和东海地区18口石油勘探钻井的井孔崩落特征，结合对琉球岛弧和冲绳海槽地区浅源地震震源机制解的分析，确认了南黄海地区与我国华北地区有类似的现代构造应力场特征；并得出东海地区的最大水平压应力方向为NEE-SWW，最小水平压应力方向为NNW-SSE，它们分别与冲绳海槽地区的最大和最小主压应力方向接近;东海地区地壳上层的水平差应力可能不强，这与该地区没什么地震活动的特点是一致的．根据应力场特征推断，我国东部地区并未受到菲律宾海板块俯冲的推挤作用，而是可能受到垂直于冲绳海槽走向的拉伸作用的影响．     

南黄海和东海地区现代构造应力场特征的研究

分析研究了南黄海和东海地区18口石油勘探钻井的井孔崩落特征,结合对琉球岛弧和冲绳海槽地区浅源地震震源机制解的分析,确认了南黄海地区与我国华北地区有类似的现代构造应力场特征;并得出东海地区的最大水平压应力方向为NEE-SWW,最小水平压应力方向为NNW-SSE,它们分别与冲绳海槽地区的最大和最小主压应力方向接近;东海地区地壳上层的水平差应力可能不强,这与该地区没什么地震活动的特点是一致的．根据应力场特征推断,我国东部地区并未受到菲律宾海板块俯冲的推挤作用,而是可能受到垂直于冲绳海槽走向的拉伸作用的影响．     

Model-based long-term reconstruction of weather-driven variations in chronic oil pollution along the German North Sea coast

Lagrangian passive tracer transport simulations covering the 46-year period 1958-2003 were utilized to compare the exposures of different parts of the German North Sea coast to ship-related chronic oil pollution. Assuming the spatial distribution of oil releases to be proportional to estimated ship traffic density, detailed drift reconstructions allowed for the reconstruction of wind-induced inter-annual variations in coastal pollution. For the winter months, a statistical relationship between simulated advective transports and prevailing sea surface pressure fields was established via Canonical Correlation Analysis. Wind effects were found to be more important for the northern (Schleswig-Holstein) than for the southern (Lower Saxony) part of the German North Sea coast. For Schleswig-Holstein, simulations showed consensus with beached bird survey data from this region. Proper identification of weather-driven inter-annual and spatial variations in monitoring data helps to avert misjudgments with regard to trends in the general level of chronic oil pollution.     

Measuring ignitability for in situ burning of oil spills weathered under Arctic conditions: from laboratory studies to large-scale field experiments

This paper compares the ignitability of Troll B crude oil weathered under simulated Arctic conditions (0%, 50% and 90% ice cover). The experiments were performed in different scales at SINTEF’s laboratories in Trondheim, field research station on Svalbard and in broken ice (70-90% ice cover) in the Barents Sea. Samples from the weathering experiments were tested for ignitability using the same laboratory burning cell. The measured ignitability from the experiments in these different scales showed a good agreement for samples with similar weathering. The ice conditions clearly affected the weathering process, and 70% ice or more reduces the weathering and allows a longer time window for in situ burning. The results from the Barents Sea revealed that weathering and ignitability can vary within an oil slick. This field use of the burning cell demonstrated that it can be used as an operational tool to monitor the ignitability of oil spills.     

An oil spill-food chain interaction model for coastal waters

An oil spill-food chain interaction model, composed of a multiphase oil spill model (MOSM) and a food chain model, has been developed to assess the probable impacts of oil spills on several key marine organisms (phytoplankton, zooplankton, small fish, large fish and benthic invertebrates). The MOSM predicts oil slick thickness on the water surface; dissolved, emulsified and particulate oil concentrations in the water column; and dissolved and particulate oil concentrations in bed sediments. This model is used to predict the fate of oil spills and transport with respect to specific organic compounds, while the food chain model addresses the uptake of toxicant by marine organisms. The oil spill-food chain interaction model can be used to assess the environmental impacts of oil spills in marine ecosystems. The model is applied to the recent Evoikos-Orapin Global oil spill that occurred in the Singapore Strait.     

Dynamics of oil product distributions in water and bottom sediments of the sea of Azov and the Black Sea after ship accidents in the Kerch Strait

The dynamics of concentrations of oil products spilled into the aquatic ecosystem as a result of accidents in the Kerch Strait is discussed. Provision is made for the analysis of the results of long-term monitoring and for the revealing of differences in concentrations and distribution of oil hydrocarbons in the Sea of Azov and in the Black Sea after emergency spills. The available information was used to outline the course of events that led to such redistribution of spilled mazut in marine ecosystems.     

Assessment of metal concentrations found within a North Sea drill cuttings pile

North Sea drill cuttings piles are a distinct anthropogenic legacy resulting from the exploration and production of North Sea oil reserves. The need to understand metal cycling within the piles becomes increasingly important with the imminent decommissioning of many North Sea platforms and the subsequent fate of associated cuttings piles. This paper presents results of the simultaneous analysis of geochemical carrier substances (Mn and Fe oxyhydroxides), along with dissolved (<0.2 microm) and total (>0.2 microm) metal (Ba, Co, Cr, Cu, Mo, Pb, V) concentrations from a North Sea cuttings pile and surrounding sediment. These data are examined in conjunction with in situ measured porewater oxygen and sulfide. Results show a rapid removal of oxygen within the top few millimeters of the cuttings pile along with elevated concentrations of total hydrocarbons and solid phase metal concentrations compared to the surrounding environment.     

Oil spills in Narragansett Bay: Comparison between federal and state records

Oil spill response in the US is divided among several jurisdictions due to separate and overlapping legislative and regulatory authority. In Rhode Island, data concerning oil spill incidents are kept by two agencies of the federal government and by one agency of the state government. Narragansett Bay and its tributaries are geographically in three jurisdictions; however, because of a tradition of good interagency cooperation, there were very few duplications in spill response. Because each agency has differing expertise and equipment, the types of spill incidents reported by each, if considered separately, present an entirely different picture of the nature of oil spills in this region. Assessment of oil spills as a source of pollution to coastal waters requires examination of all data, not only that from one agency. For Narragansett Bay and its tributaries, oil spills were a minor part of the total oil pollution budget.     

On the SAR derived alert in the detection of oil spills according to the analysis of the EGEMP

Satellite services that deliver information about possible oil spills at sea currently use different labels of “confidence” to describe the detections based on radar image processing. A common approach is to use a classification differentiating between low, medium and high levels of confidence. There is an ongoing discussion on the suitability of the existing classification systems of possible oil spills detected by radar satellite images with regard to the relevant significance and correspondence to user requirements. This paper contains a basic analysis of user requirements, current technical possibilities of satellite services as well as proposals for a redesign of the classification system as an evolution towards a more structured alert system. This research work offers a first review of implemented methodologies for the categorisation of detected oil spills, together with the proposal of explorative ideas evaluated by the European Group of Experts on satellite Monitoring of sea-based oil Pollution (EGEMP).     

Marine litter distribution and composition in the North Sea

Following the development of marine litter surveillance methodologies for use on beaches, this study shows the feasibility of similar surveys at sea. The results indicate widespread distribution of marine litter in the surface waters of the North Sea, especially plastics. Not only does this draw attention to the need for the implementation of Annexe V of the MARPOL Convention, but serious consideration should be given now to the designation of the North Sea as a ‘special area’ such that the dumping of all garbage from ships, except food wastes, should be prohibited.     

Taxonomic level for assessing oil spill effects on soft-bottom sublittoral benthic communities

Infralittoral soft-bottom macrofauna abundance data collected during four-year surveys after the Aegean Sea (Galicia, Spain) and the Amoco Cadiz oil spill (Brittany, France) at a total of seven sites were analysed at three different taxonomic levels (species, genus, and family). The effects of the spills on macrofauna populations were very similar in the two areas. The post-spill time-courses of Shannon-Weaver diversity values were similar regardless of whether species-, genus- or family-level data were used. Non-metric multidimensional scaling identified well-defined groups of samples corresponding to different times post-spill, and again the results obtained were very similar regardless of the taxonomic level considered. In general, the use of genus- or family-level data did not lead to relevant information loss by comparison with species-level data. In view of these findings and those of previous studies of this type, we conclude that family-level data is generally sufficient for monitoring pollution effects in infralittoral soft-bottom environments.