Stable Continental Region Earthquakes in South China

— This paper reviews some remarkable characteristics of earthquakes in a Stable Continental Region (SCR) of the South China Block (SCB). The kernel of the SCB is the Yangtze platform solidified in late Proterozoic time, with continental growth to the southeast by a series of fold belts in Paleozoic time. The facts that the deviatoric stress is low, the orientations of the major tectonic features in the SCB are substantially normal to the maximum horizontal principal stress, and a relatively uniform crust, seem to be the major reasons for lack of significant seismicity in most regions of the SCB. Earthquakes in this region are mainly associated with three seismic zones: (1) the Southeast China Coast seismic zone related to Guangdong-Fujian coastal folding belt (associated with Eurasia-Philippine Sea plate collision); (2) the Southern Yellow Sea seismic zone associated with continental shelf rifts and basins; and (3) the Downstream Yangtze River seismic zone spatially coinciding with Tertiary rifts and basin development. All three seismic zones are close to one or two major economic and population centers in the SCB so that they pose significant seismic hazards. Earthquake focal mechanisms in the SCB are consistent with strike-slip to normal faulting stress regimes. Because of the global and national economic significance of the SCB and its dense population, the seismic hazard of the region is of outstanding importance. Comparing the SCB with another less developed region, a pending earthquake with the same size and tectonic setting would cause substantially more severe social and economic losses in the SCB. This paper also compiles an inventory of historic moderate to great earthquakes in the SCB; most of the data are not widely available in English literature.     

Pollution and the offshore oil industry

Exploration and exploitation of the North Sea oil field has caused a good deal of concern about the possibility of major pollution. Three major accidents to offshore wells are examined to discover the risk and likely consequences of a blow-out in the North Sea.     

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.     

Seabird biomass and food consumption in the North Sea

Calculations presented by Bourne (1983) contain some order-of-magnitude errors, and give the misleading impression that estimates of fish consumption by seabirds in the North Sea may be as low as 0.25%, or as high as 48%, of fish production, depending on the method of calculation. It is likely that the true figure is closer to 20% once the errors in Bourne's calculations are corrected, but several areas of uncertainty require further study; particularly seabird diets and foraging ranges, fish distributions and movements. Studies from other parts of the world show that seabird numbers can dramatically alter in response to changes in food abundance. Some changes result from natural perturbations and others from effects of overexploitation of fish stocks by man. Effects of overfishing seem likely to be potentially at least as serious as effects of oil or chemical pollution in many regions, possibly including the North Sea.     

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.     

Biomonitoring of pollution by Cerastoderma edule from the British Isles: a Laser Ablation ICP-MS study

Shells of the common cockle Cerastoderma edule have been analysed using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) for a suite of elements (Pb, Cu, As, Zn and U). The samples of C. edule were obtained from four sites in the British Isles, two facing the Atlantic and two adjacent to the Irish Sea. The LA-ICP-MS technique, permits high resolution examination of the relationship between the concentrations of elements in the hard parts and that in the environment. This study shows that this bivalve can be used as a biomonitor of pollution. All four areas under investigation are affected by anthropogenic pollution, in particular Zn and Cu, and are characterized by short-term extreme pollution events. Furthermore, high levels of U are recorded from the cockles sampled from the sites adjacent to the Irish Sea, probably related to a combination of both natural and industrial effluents discharged into the area.     

渤海海域现代构造应力场的数值模拟

根据渤海海域的构造演化背景和地质构造特征建立了该区的二维地质模型,用二维有限元方法计算模拟了渤海海域现代构造应力场,获得了该区构造应力场的分布特征;同时,根据计算结果把渤海海域的构造应力场分为辽东湾、渤中、渤东和渤西等4个区域,并对这4个区域在构造应力场上的差异性进行了描述。从渤海海域整体的应力分布可以看出,该区新近纪以来的断裂活动总体水平上西部较东部强烈,海域东部沿郯庐断裂带仍有较高的断裂发育程度及断裂张开性,而海域中部地区的断层发育程度、活动位移均较低     

Oil pollution in the Cromarty Firth

Cromarty Firth on the north-east coast of Scotland is an area of international importance to wildfowl, and the whole area has been designated a ‘Site of Special Scientific Importance’ by the Nature Conservancy Council. There are proposals to establish National Nature Reserves in two bays in the Firth. The area has also become a centre of activity for the oil industry exploiting the North Sea oilfield. Repeated oil spillages are threatening the conservation value of the area and unless strong measures are taken to reduce and treat oil pollution from all sources, there could be enormous damage to wildlife.     

Present state of oil pollution in the northern Indian Ocean

A consolidated picture of oil pollution for the northern Indian Ocean is presented. Oil slicks were sighted on 5582 observations, about 83.5% of the total observations of 6689. The range of concentrations, of the floating tar balls, is 0–6.0 mg/m² in the Arabian Sea. Similarly, the oil tanker route in the Bay of Bengal has the range of 0–69.75 mg/m². North of this route, the Bay of Bengal is comparatively free from this floating tar. Mean concentrations of dissolved and dispersed hydrocarbons for 0–20 m are 32.5 and 24.1 μg kg^?1, respectively, in the Arabian Sea and the Bay of Bengal.     

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.     

Charging for port reception facilities in North Sea ports: putting theory into practice

The aim of this paper is to evaluate the charging systems for the use of port reception facilities for waste oil, and to examine the potential impact of the charging elements of the new (late 2000) EU Directive on port reception facilities for ship-generated waste and cargo residues. Experience to date with alternative models for charging is considered. Conclusions are drawn about the effectiveness of the EU Directive as a means of controlling pollution in the North Sea and producing a 'level playing field' between ports.     

Firth of Forth oil pollution incident, February 1978

Where seaducks and other waterfowl are highly concentrated, even small quantities of oil can be a major hazard. A pollution incident on the Firth of Forth in February 1978 was notable in that it affected 241 Great Crested Grebes Podiceps cristatus (a high proportion of those present at the time) as well as 700 diving ducks. Evidence is provided indicating that the slick passed close to the main wildfowl feeding area at night, oiling nocturnal-feeding Scaup Aythya marila and Pochard A. ferina and a raft of roosting grebes, while Eider Somateria mollissima and Goldeneye Bucephala clangula, which had moved elsewhere to roost, largely escaped. The behaviour of freshly oiled birds is described. Heavily oiled Pochard flew 7 km inland to a loch before they were incapacitated. This is the sixth oil pollution incident to affect a large number of birds on the Forth since January 1970.     

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.     

Seabirds in the North Sea Demobilized and Killed by Polyisobutylene (C4H8)n (PIB)

This paper reports on a mass stranding of seabirds in the North Sea in December 1998. Hundreds of birds were washed ashore alive in Zeeland (SW Netherlands), covered in a whitish, sticky substance, and were transported to a rehabilitation centre. About 10 days later, more (dead) casualties washed ashore further to the north on Texel and along the mainland coast, again covered in a glue-like substance. Common guillemots Uria aalge, northern fulmars Fulmarus glacialis and common scoters Melanitta nigra were the most numerous birds affected in this incident. Both strandings were temporarily (10 days) and geographically separated (ca. 120 km apart), but were apparently caused by a single source of pollution. The meteorology at the time was consistent with the course of a single incident. At least 1100 seabirds were affected by this substance, soon identified as polyisobutylene (C₄H₈)_n. PIB is known as a non-toxic, non-aggressive substance. Volunteers cleaning the birds in the rehabilitation centre reported serious discomfort and dizziness and the soft parts of the PIB-affected birds found dead (bill, eye, throat, feet, webs) appeared to dissolve in a few days time. Both effects cannot be attributed to PIB, and are therefore unexplained. Although the dumping of PIB in the marine environment is not explicitly prohibited under MARPOL, the effects on wildlife observed are enough to plead for counter-measures.     

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.     

Biotransformation of oil hydrocarbons in Karkinitskii Bay of the Black Sea: Assessment based on mathematical modeling

The transformation conditions of oil hydrocarbons in water are considered for the case of Karkinitskii Bay, the Black Sea, where gas deposits have been developed actively in recent years and oil product pollution of marine environment has been recorded repeatedly. Data on measured oil hydrocarbon concentrations, their input into the northwestern part of the Black Sea, and experimental estimates of oil decomposition in the marine environment are presented. The biotransformation conditions of oil hydrocarbons are simulated by reproducing the biochemical activity of microflora and effecting substrate consumption processes, metabolic product excretions, and biomass decay. These processes maintain the biogenic substance turnover in water environment. The calculations are based on the morphometric characteristics of Karkinitskii Bay, and mean long-term data on the monthly dynamics of marine environmental characteristics (temperature, light intensity, transparency, atmospheric precipitation, and the characteristics of water regime and Danube runoff). A check calculation was performed to reproduce the concentration dynamics of biogenic substances and oil products with allowance made for the effect of river runoff and background pollution of the marine environment. The numerical scenarios take into account the marine environmental pollution conditions (an immediate discharge of 1000, 500, or 200 t of oil products per week) in winter, spring, summer, and autumn. The obtained model estimates of the rates of oil product decomposition and oxygen consumption are shown to agree well with experimental data. The time required for the concentration of oil products to reach the MAC after pollution of the marine environment is estimated.     

Changes in the marine pollution management system in response to the Amorgos oil spill in Taiwan

The Marine Pollution Control Act (MPCA) of Taiwan was promulgated on November 1, 2000, with the specific aim of controlling marine pollution, safeguarding public health, and promoting the sustainable use of marine resources. In addition to land-based pollution, oil spills are one of the most significant threats to the local marine environment largely on account of the some 30,000 tankers which pass through Taiwan’s coastal waters each year. In January 2001, two months after the enactment of this newly-introduced law, a Greek merchant vessel, the Amorgos ran aground in the vicinity of a national park on the southern tip of Taiwan, causing a serious oil spill and leading to considerable changes with regard to the marine pollution management system. The incident brought to the forefront many serious problems, such as a lack of experience, expertise as well as equipment required to respond to such disasters, as well as the ambiguous, unclear jurisdiction among related agencies. Thus, this paper reviews the incident of the Amorgos spill, identifies the major issues and lessons learned, and proposes several recommendations in an effort for Taiwan to further improve its marine pollution management system.     

Impaired osmoregulation in the shrimp Palaemon adspersus exposed to crude oil extract

Palaemon adspersus is a hyper- and hypo-osmoregulating shallow-water shrimp. For a maximum period of 34 days P. adspersus were exposed to 20, 70, 100 and 200 ppb WSF of North Sea crude oil. The osmotic concentration of the haemolymph was measured by freezing point depression once a week. The ability to maintain hyper-osmolality was significantly decreased (p<0.05) after one, two and three weeks exposure to 200, 70 and 100 ppb, respectively. No effect was observed in 20 ppb. After an accidental exposure of shrimps to 24 h acute oil pollution, they were placed in pure sea water. The ability to maintain hyper-osmolality was reduced one week after the accidental oil exposure, but was regained within three weeks.     

Pelagic tar, dissolved/dispersed petroleum hydrocarbons and plastic distribution in the Cretan Sea, Greece

During the first cruise of R/V ‘Philia’ in July 1997 within the framework of the TALOS programme supported by the Greek Ministry of Physical Planning and Public Works, the sampling of floating tar, litter and sea water for dissolved/dispersed petroleum hydrocarbons (DDPH) was carried out in the Cretan Sea. Analysis of these data has allowed a first assessment of the status of floating marine pollution in the region. DDPH measurements showed a mean concentration of 0.145 μg/l of chrysene equivalents (n = 24). Tar and plastics concentrations were in the range of 1–4280 and 0–1160 μg/m², respectively. Mean pelagic tar concentration was 318 μg/m², more than two times higher than what was reported for the area in previous studies. Based on in situ hydrographic observations there is strong evidence that most of the floating tar enters the Cretan Sea through the Ionian Sea.     

On tectonic character of the connection zones of the Earth’s crust in the South Caspian Basin and Scythian–Turan plate based on seismological data

The features of the spatial distribution of earthquake sources in the South Caspian Basin (SCB) are considered in relation to the regional deep structure. The results of analysis showed that the SCB and Scythian–Turan plate are divided by deep faults of small length with a west–northwest trending. These faults are included in the Apsheron–Balkhan threshold zone. The opinion of some researchers about subduction of the SCB crust under the epi-Hercynian platform of the northern Caspian Sea has not been confirmed.