Petroleum hydrocarbons in the Mediterranean Sea: A mass balance

Over three quarters of a million tonnes of oil were estimated to be introduced annually into the Mediterranean Sea from land-based and open-sea discharges. This paper is a critical assessment of data available through 1983 on the distribution of petroleum-derived hydrocarbon residues and the biogeochemical processes controlling the transport and fate of organic contaminants in this regional sea ecosystem. Inputs, outputs and ecosystem partitioning or inventories are computed and a complete mass balance model is proposed. The approach raises several implications with respect to strategies for the sampling and analysis of organic contaminants in ocean ecosystems. The report also provides a basis on which to evaluate the effectiveness of recent discharge regulations in reducing pollution loads in the Mediterranean. The agreement between calculated fluxes, inventories and input time scales demonstrates the usefulness of organic contaminants as markers for the development of global and ocean flux models.     

Factors influencing the abundance of deep pelagic bioluminescent zooplankton in the Mediterranean Sea

Measurements of the density of deep pelagic bioluminescent zooplankton (BL) were made with the Intensified Silicon Intensifier Target (ISIT) profiler in the Ligurian, Tyrrhenian, Adriatic, Ionian Seas and the Strait of Sicily from ～300 m to near seafloor. Mean BL densities ranged from 2.61 m^?3 at 500–1000 m depth in the Adriatic Sea to 0.01 m^?3 at 4000–5000 m depth in the E Ionian Sea. We investigated drivers of spatial variation of deep pelagic BL density. Linear regression was applied between surface chlorophyll a (Chl a) concentration and underlying BL density. Chl a values were determined from satellite derived 100 km radius composites (six 10-day means per ISIT deployment, over preceding 60 days). At 500–1000 m depth we found a significant positive relationship between mean BL density and mean Chl a in the period prior to 0–10 days (at 1% level) and prior to 10–40 days (at 5% level). Beyond 40 days no relationship between BL density and Chl a was found at this depth. At depths 1000–1500 m BL density values were low and no significant relationship with Chl a was detected. Generalised additive modelling (GAM) was used to assess the influence of benthic hotspots (seamount; cold water coral mound; mud volcano) on overlying BL density. A reduction in BL density was found downstream of the Palinuro seamount from 300 to 600 m. No effect on BL density in the overlying water column was detected from the presence of cold water corals. Higher BL densities were detected over the W Madonna dello Ionio mud volcano than at other sites sampled in the NW Ionian Sea. We find surface Chl a to be a good predictor of BL density in the mesopelagic zone; below this depth we hypothesise that processes affecting the efficiency of particle export to deep water may exert greater influence on BL density.     

Chlorinated hydrocarbons in the open mediterranean ecosystem and implications for mass balance calculations

Studies on the biogeochemical cycling of organic contaminants in the Mediterranean have demonstrated the importance of polychlorinated biphenyls (PCBs) as relatively stable markers of recent anthropogenic influence in ocean systems. This paper presents results of hydrocarbon analyses of deep water profiles, sediments and their associated surface flocculent layers, and zooplankton samples collected in the western basin. Seawater concentrations were higher than those previously reported for the eastern basin and were consistent with the presence of industrial sources in the northwestern segment. In the water column, the percent of PCBs associated with filterable particles was related to the ambient concentrations of total suspended matter, distance from coastal input sources and on depth. The occurrence of deep water residues primarily in the dissolved phase and observations of subsurface maxima in seawater concentrations during a season of high surface productivity were consistent with the predictions of vertical transport models based on residues associated with sinking particles and equilibrium partitioning. Flocculent layers at the sea/sediment interface contained two and three orders of magnitude, respectively, more PCBs and petroleum hydrocarbons (PHCs) than their associated surface sediments. The flocculent particles also contained several biogenic hydrocarbons presumably originating from plankton and relatively soluble and labile contaminants such as hexachlorohexane isomers (HCH) and hexachlorobenzene (HCB), thus confirming that the majority of the flux of hydrocarbons to sediments is carried on rapidly settling large particles. By combining the sediment and flocculents data with published sedimentation rates for the deep basins of the Mediterranean, a yearly flux rate of PCBs to the open sea sediments was estimated as 13 μg m⁻² yr⁻¹ or less than half of the rate measured in a coastal sediment trap experiment. Analytical results are placed in the context of other distribution data for PCBs and long-term flux studies to construct a partial mass balance budget for this semi-enclosed sea. The computed coastal inventory showed that about 35% remains suspended in the water column while the majority of residues are deposited in coastal sediments. However in the open sea, the deep water column may contain up to 70% of the total inventory and may be a continually increasing reservoir of stable organic contaminants reaching the ocean. The budget shows that priority for improved research and monitoring efforts in ocean systems should be given to continued advancement in techniques for the precise measurement of deep water concentrations and for measuring current atmospheric inputs and sedimentation rates in order to develop more accurate ocean flux models.     

Chlorinated hydrocarbons in the North Pacific and Indian Oceans

PCBs, DDT compounds and HCH isomers were detected in the air and surface waters of the North Pacific and Indian Oceans, including the Bering Sea, East China Sea, South China Sea, Bay of Bengal and the Arabian Sea. The general concentrations of each chlorinated hydrocarbon were as follows: water PCBs 0.1 to 1.0, DDT 0.01 to 1.0, HCH 1.0 to 10 ngl ^–1; air DDT 0.01 to 1.0, HCH 0.1 to 10 ng m^–3. PCB concentrations in surface waters were slightly lower than those of the North Atlantic and North Sea previously reported, while DDT concentrations in the air and water were higher. Remarkably high concentrations of DDT and HCH were found in the air off the western coast of India. Also in the Pacific site off Central America, a fairly high concentration of DDT was observed in an air sample. These data suggest that large amounts of DDT and HCH are being used in the tropical zone, especially in southern Asia. Furthermore, high concentrations were observed both in the air and water of the Northwest Pacific between 30°N and 40°N latitude. There is a possibility that both pesticides are not only still being used in lower latitude countries but also in the mid-latitude ones of the Asian continent excluding Japan. In addition to this atmospheric circulation may also contribute to the concentration of these pesticides in the mid-latitudinal zone.     

Aliphatic hydrocarbons in particulate matter from the Baltic Sea

During May 1980, particulate matter was collected at an anchor station from different depths by two methods. In the separated hydrocarbon fraction the most abundant component was the highly unsaturated hydrocarbon n-heneicosahexaene (HEH). Also present was a series of mono- and di-unsaturated olefinic hydrocarbons with an uneven number of carbon atoms, starting with n-C₁₇. The alkane pattern was characterized by a maximum in the range between n-pentadecane and n-heptadecane, with a strong uneven to even carbon number predominance. The peculiar composition of the aliphatic hydrocarbons was compared with literature data given for aliphatic hydrocarbons, whether produced by different marine organisms or derived from crude oil of other anthropogenic sources. A suggestion is made for using a set of conditions as indicators for pollution by fossil hydrocarbons.     

地中海的泥火山

最近在地中海东部海底发现了大量的泥火山。地质学家将顶部带有漏斗状火山口的并具有通向深部的管孔 ,并且可涌出混有泥质粘土质沉积物的水、气的大型圆锥形山丘称之为泥火山 ,有时伴有类同于一般火山的强烈的喷发。泥火山的产生是由于细粒岩石 (通常是富含死火山角砾岩和水的粘土 )受到强烈的挤压 ,粘土中还混有气态的硫化氢。这样的混合物形成半液态粥状物 ,以冒气泡的流质形态向上被压出。在多次重复的喷发过程中 ,海底形成了大量布满污泥、经常浸透了石油产物的地下圆丘和“烤饼”。我们发现 ,这种形成物经常可以在由俯冲作用产生的增生…     

Chlorinated hydrocarbons and hatching success in Baltic herring spring spawners

Eggs from 69 females of spring spawning herring from the German Baltic coast (Travemünde, April 1979) were incubated in clean sea water (20‰ S, temperature 8°C) under standard conditions. Sixty-one trials could be used for the evaluation of hatching success. Viable hatch was taken as a measure to evaluate the effects of chlorinated hydrocarbons accumulated in gonads, liver and muscle of parental fish.PCB levels in running ripe females ranged on a wet weight basis between 19 and 241 ng g^?1 (gonad), 20 and 377 ng g^?1 (liver) and 11 and 1820 ng g^?1 (muscle). Concentrations of other chlorinated hydrocarbons (DDD, DDE, γ-HCH, etc.) were in the same range as reported by other authors for Baltic herring (Huschenbeth, 1973, 1977). Viable hatch was significantly affected at ovary DDE concentrations higher than 18 ng g^?1 (wet wt) and PCB concentrations of more than 120 ng g^?1 (wet wt).Results are compared with data obtained during earlier investigations with flounder eggs.     

Diagenetic magnetic enhancement of sapropels from the eastern Mediterranean Sea

Diagenetic dissolution of magnetic minerals has been widely observed in organic-rich sediments from many environments. Organic-rich sediments from the eastern Mediterranean Sea (sapropels), recovered during Leg 160 of the Ocean Drilling Program, reveal a surprising catalogue of magnetic properties. Sapropels, from all sites studied across the eastern Mediterranean Sea, are strongly magnetic and the magnetization is directly proportional to the organic carbon content. The magnetization of the sapropels is dominated by a low-coercivity, probably single domain magnetic mineral (with an inverse magnetic fabric) that exhibits a clear decay in magnetic properties when exposed to air. During heating, the magnetic particles irreversibly break down between 360 and 400°C. The contrast between the magnetic properties of sapropels and surrounding sediments is marked, with remanence intensities of sapropels often being more than three orders of magnitude higher than those of underlying sediments. The contrast between the magnetic properties of sapropels and the surrounding sediments is apparently controlled by non-steady-state diagenesis: sulphate-reducing conditions dominated during sapropel deposition, while overlying sediments were deposited under oxic conditions. The mineral responsible for the magnetic properties of sapropels is most likely to have formed under sulphate-reducing conditions that existed during times of sapropel formation. Attempts to identify this mineral have been unsuccessful, but several lines of evidence point toward an unknown ferrimagnetic iron sulphide phase. The influence of diagenesis on the magnetic properties of cyclically-deposited eastern Mediterranean sedimentary sequences suggests that magnetic parameters may be a useful proxy for diagenesis in these sediments.     

Managing Bluefin Tuna in the Mediterranean Sea

Atlantic Bluefin Tuna is an important but not well managed fishery in the Mediterranean Sea. In this paper, management system is evaluated with information on stock status, resource rent, and total employment. The non-restrictive implementation of International Commission for the Conservation of Atlantic Tunas (ICCAT) policies is found to be the institutional reason for its management failure, while the common-property and shared stock nature of this fishery is the fundamental reason. To address these major issues, policy schemes are proposed to help sustainably manage this valuable resource in the Mediterranean Sea.     

Chlorinated hydrocarbons in seawater: Analytical method and levels in the northeastern Pacific

A method is described for analyzing nanogram quantities of chlorinated hydrocarbons from 1-1 samples of seawater. Seawater samples are pumped through a copper column containing a mixture by weight of 5% activated carbon powder, 10% MgO and 85% refined diatomaceous earth. The chlorinated hydrocarbons in the seawater are adsorbed or trapped on the column and subsequently eluted with 30% benzene in acetone (v/v) for analysis by gas-liquid chromatography.This procedure was used to analyze chlorinated hydrocarbon levels in samples collected off the southern California coast. We suggest that anthropogenic chlorinated hydrocarbons can be used for the investigation of large-scale ocean currents and mixing processes.     

Marine organic geochemistry of the Eastern Mediterranean: 1. Aliphatic and polyaromatic hydrocarbons in Cretan Sea surficial sediments

As part of a lipid biogeochemical study, aliphatic and polyaromatic hydrocarbons were determined in surficial sediments from the Cretan Sea (South Aegean Sea) in the Eastern Mediterranean. Total concentrations of both aliphatic (AHC) and polyaromatic (PAH) hydrocarbons were low (562–5697 and 14.6–158.5 ng/g, respectively) with respect to other coastal sediments worldwide and compare with concentrations found in open sea areas. The composition of AHC was dominated by unresolved complex mixture (UCM) indicating the presence of petroleum-related hydrocarbon inputs as confirmed by the detection of specific α,β-hopanes. PAH consisted mainly of pyrolytic four- to five-ring compounds. UCM and PAH amounts revealed that Cretan Sea receives low supply of anthropogenic material compared to NW Mediterranean. The spatial distributions of AHC and PAH indicated that urban run-off and transport from the continental self are the major input pathway of anthropogenic and biogenic hydrocarbons from terrestrial sources in the near shore area, whereas atmospheric transport might be the significant source of hydrocarbons in the deep area.     

东海浮游介形类(Ostracods)分布特征

根据1997~2000年东海(23°30'~33°00'N,118°30'~128°00'E)海域四季海洋调查资料,探讨了东海浮游介形类分布特征及与环境的关系.结果表明:东海浮游介形类丰度占浮游动物总丰度的3.47%;春、夏、秋和冬四季平均丰度分别为0.70,1.72,2.57和0.90个/m3;冬春季的短棒真浮萤(Euconchoecia chierchiae),夏季的后圆真浮萤(Euconchoecia maimai)和秋季的齿形海萤(Cypridi-na dentata)分别是各季的主要优势种;夏、秋季介形类总丰度与水文环境因子的线性相关性不显著,春季与表层盐度相关,冬季与表层温度相关.东海北部外海四季均有介形类高丰度区出现,但在东海北部近海长江口及其邻近舟山水域,介形类数量相对较低.在东海南部,冬春季高丰度区位于外海,夏秋季在近海.东海浮游介形类基本上是一大类较为典型的暖水性且具有集群行为的海洋浮游动物.介形类秋季高丰度区和较高丰度区的分布与太平洋褶柔鱼(Todarodes pacificus)、绿鳍马面鲀(Navodon Septentrionalis)、鲐鯵鱼类等渔场的位置基本一致,在渔业上有重要的意义.     

Chlorinated hydrocarbons in the seawater and surface sediments of Blanca Bay,Argentina

In order to characterize our study area and to provide reference values to be used in the future to measure the changes produced by an increase in contamination, the concentrations of chlorinated hydrocarbons have been investigated in fifty-one samples of seawater, taken at four different depths: air-sea interface, surface, one metre and bottom waters, and in twenty-three samples of surface sediments from Blanca Bay, Argentina. Of eleven organochlorine compounds we were looking for (α BHC, lindane, heptachlor, δ BHC. aldrin, heptachlor epoxide, dieldrin, o-p′DDD, p-p′DDD, o-p′DDT and p-p′DDT), seven could be detected in seawater and three in surface sediments with the following mean concentrations: α-BHC=48·2 ng l^?1; lindane=54·2 ng l^?1; heptachlor=45·0 ng l^?1; δ BHC=12·5 ng l^?1; aldrin=61·8 ng l^?1 and ΣDDT=67·0 ng l^?1; and δ BHC=3·2 ng g^?1; lindane=4·2 ng g^?1 and heptachlor=1·0 ng g^?1 for seawater, regarding the surface waters, and sediment samples, respectively.Concentration factors among the different water layers were also studied to see if there was any correlation between chlorinated hydrocarbon contents and the water depths from which the samples were taken. As a mean value, the air-sea interface water contains 18 times more of these compounds than that of the water near the bottom. A comparison of the values corresponding to seawater and surface sediments from our study area with those levels measured in samples from other geographic locations is also presented.With the purpose to detect a relationship between chlorinated hydrocarbon concentrations and the contents of particulate matter (PM) on the one hand, and particulate organic material (POM) on the other hand, four groups of samples containing different amounts of PM and POM, respectively were formed. From a comparison of the results obtained, lindane, heptachlor and δ BHC showed a tendency to lower concentrations in those samples containing little PM whereas α BHC and aldrin remained without important changes. No significant correlation was found between organochlorine levels and contents of POM.     

Polycyclic aromatic hydrocarbons in water, seston and copepods in a harbour area in the Western Mediterranean (Ligurian Sea)

Polycyclic aromatic hydrocarbons (PAHs) are widespread carcinogenic, mutagenic and teratogenic pollutants that can significantly affect ecosystems and exert an influence on marine planktonic and benthic communities as well as on higher organisms such as fish and mammals, including humans. In this paper the concentrations of six PAHs in water, seston and copepods were examined in a harbour zone of the Genova Gulf (Ligurian Sea) from November 1997 to June 1998. The importance of freshwater inputs coming from a polluted stream and the influence of seasonal and atmospheric factors were also considered. Highest PAH values were recorded during spring. Fluoranthene, Benzo[b]fluoranthene and Benzo[k]fluoranthene were the most abundant PAHs either in water, seston or copepods. The concentration of total PAHs in seawater was often lower than the detection limit: recorded values ranged between 0.001 and 0.06 ppb. In seston, total PAHs ranged between 0.033 and 6.26 ng·g^?1 and in copepods between 0.01 and 2.34 ng·g^?1. With this study, PAH contamination in the harbour zone of Genova Sestri‐Ponente and the importance of inputs of organic pollutants coming from land and freshwaters have been emphasized.     

Bacterial and primary production in the pelagic zone of the Kara Sea

Data on the bacterial and primary production, which were obtained simultaneously for the same water samples, are presented for three regions of the Kara Sea. The samples were collected for the transect westwards of the Yamal Peninsula, along the St. Anna Trough, and the transect in Ob Bay. Direct counts of the DAPI-stained bacterial cells were performed. The bacterial production and grazing rates were determined using a direct method when metabolic inhibitors vancomycin and penicillin were added. The primary production rates were estimated using the ¹⁴C method.     

Mass balance of mercury in the Mediterranean Sea

The Mediterranean Basin is rich in mercury from natural and anthropogenic sources. During an extensive research from 2002–2005, measurements of different mercury forms were carried out in the Mediterranean Sea by the Italian research vessel Urania as a part of the Med Oceanor and MERCYMS projects funded by the EU Framework programme. Further on, transport and fate of mercury forms was simulated in water and air compartments by two different models, and an approximate coupling of both models was performed. The new 3-dimensional model PCFLOW3D was completed with the first version of a biogeochemical module which deals with various mercury species in dissolved and particulate forms. Exchange with the bottom and the atmosphere, methylation, demethylation, reduction and oxidation were taken into account. Based on the integrated hydrodynamic-atmospheric model and results of field measurements the mass balance of total mercury in the Mediterranean Sea was determined in order to estimate main sources and sinks and simulate future trends of mercury contamination in the Mediterranean. The following terms were taken into account: sources of mercury from major rivers and from point sources, exchange with the Atlantic Ocean and the Black Sea, estimated natural sources from geotectonic active areas in the sea, exchange with bottom sediments, and evasion to and deposition from the atmosphere.     

Aliphatic hydrocarbons in Great Barrier Reef organisms and environment

This investigation was undertaken to assess the chemical nature, occurrence, and possible origin of petroleum hydrocarbons in the Great Barrier Reef ecosystem. Aliphatic hydrocarbons in surface sediments, water, and a suite of seven species from widely separated coral reefs in the Great Barrier Reef area were analysed by gas chromatography, and by gas chromatography coupled with mass spectrometry. The hydrocarbons found were substantially of biogenic origin. The major components were n-pentadecane, n-heptadecane, pristane and mono-alkenes based on heptadecane, and were believed to originate from benthic algae and phytoplankton. There was no evidence to suggest that lipid content had any influence on hydrocarbon content. Hydrocarbons from the organisms and sediments have characteristic composition patterns which would be altered by the presence of petroleum hydrocarbons. An unresolved complex mixture, usually considered indicative of petroleum contamination, was found in greater than trace amounts only in Holothuria (sea cucumber) and Acropora (coral) from the Capricorn Group, and in some sediment samples from the Capricorn Group and Lizard Island area.     

Soil-sized eolian dusts from the lower troposphere of the eastern Mediterranean Sea

Soil-sized eolian dusts have been collected by a mesh technique from the lower troposphere of the eastern Mediterranean. The overall average dust-loading in this region is 14 μg m^?3 of air, which is among the highest recorded for maritime soil-sized dusts.There are two distinct dust populations in the eastern Mediterranean; these have been termed the “northeastern Mediterranean assemblage” and the “southeastern Mediterranean assemblage”.The dusts of the “northeastern assemblage” originate in the soils of southern Europe. The average dust-loading of this assemblage is 12 μg m^?3 of air, and illite is the principal clay mineral with secondary amounts of kaolinite and the smectites. These dusts make only a secondary contribution to the land-derived material in the underlying deep-sea sediments.The dusts of the “southeastern assemblage” have their origin in the desert belts of North Africa and the Middle East. Their average dust-loading is 17 μg m^?3 of air, and kaolinite is their dominant clay mineral. Dusts of the “southeastern assemblage” make an important contribution to the land-derived fractions of some eastern Mediterranean deep-sea sediments.In addition to eolian dusts, river-transported material from the island of Cyprus has also been investigated. The effects of this “Cyprus assemblage” on sedimentation in the eastern Mediterranean is confined to the immediate vicinity of the island itself.     

Natural variability of hepatic biomarkers in Mediterranean deep-sea organisms

Biomarker assays are widely used as proxies for contaminant-induced effects in aquatic organisms. However, in many cases, their intrinsic natural variability due to exogenous and endogenous factors makes the interpretation of biomarker data difficult. In the present study, we investigated the natural fluctuations of six hepatic biomarkers, namely ethoxyresorufin-O-deethylase (EROD) in fish and pentoxyresorufin-O-deethylase (PROD) in crustacea, catalase (CAT), carboxylesterase (CbE), glutathione-S-transferase (GST), total glutathione peroxidase (GPX) and glutathione reductase (GR) in two deep-sea fish species, namely Alepocephalus rostratus and Lepidion lepidion and the decapod crustacean Aristeus antennatus. The NW Mediterranean deep-sea environment is characterized by very stable temperature and salinity conditions, allowing the exclusion of these two factors as potential sources of interference with biomarker activities. Biomarker results exhibited a clear influence of reproductive processes on enzyme activities, in particular in A. rostratus, which presented a pronounced seasonal pattern linked to variations in the gonadosomatic index (GSI). In addition, other factors such as food availability may also have influenced the observed variability, in particular in specimens of L. lepidion, which did not exhibit variations in reproductive activity throughout the sampling period. Depth-related variability did not exhibit a clear trend and fluctuations across sampling depths were not attributable to any specific factor. Body size had also a significant influence on some biomarkers, although allometric scaling of certain enzyme activities appears to be species-specific. The present work has thus shown that despite the lack of fluctuations of abiotic parameters such as temperature and salinity, biomarker activities in deep-sea organisms still exhibit significant variability, mainly as a result of reproductive processes and food availability.     

Vertical Land Motion in the Mediterranean Sea from Altimetry and Tide Gauge Stations

We have computed estimates of the rate of vertical land motion in the Mediterranean Sea from differences of sea level heights measured by the TOPEX/Poseidon radar altimeter and by a set of tide gauge stations. The comparison of data at 16 tide gauges, using both hourly data from local datasets and monthly data from the PSMSL dataset, shows a general agreement, significant differences are found at only one location. Differences of near-simultaneous, monthly and deseasoned monthly sea level height time-series have been considered in order to reduce the error in the estimated linear-term. In a subset of 23 tide gauge stations the mean accuracy of the estimated vertical rates is 2.3 ± 0.8 mm/yr. Results for various stations are in agreement with estimates of vertical land motion from geodetic methods. A comparison with vertical motion estimated by GPS at four locations shows a mean difference of ?0.04 ± 1.8 mm/yr, however the length of the GPS time-series and the number of locations are too small to draw general conclusions.