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More and more, the coastal regions of the world suffer from the contamination of petroleum hydrocarbon [principally polycyclic aromatic hydrocarbons (PAHs)]. This contamination can be acute, as it happened in the Coast of Galicia (NW, Spain) by the oil spill from a tanker, or chronic by the existence of high maritime traffic and a lot of industries as it is the case of the Bay of Algeciras (BA) (SW, Spain). It is of a great concern due to the toxicity, especially in sediments and ecosystem associated to it. The objective of this study is to assess, through chronic bioassay, sediment toxicity in samples collected in different littoral areas of Spain and to compare the damage caused in benthic fish, Solea senegalensis, according to that which suffers acute spill (Coast of Galicia) or chronic spill (the BA) by means of histopathology methods and enzymatic activities studies. Organisms were exposed to different sediments from Galician Coast and the BA during 42 days and every sample was analyzed by triplicate in glass aquaria. At the end of the bioassay, histopathological diseases were analyzed in the gills, target organ. Likewise, stress parameters as ethoxyresorufin-O-deethylase (EROD) and the glutathione S-transferases (GSTs) activities were determined in the liver. Results showed a significant positive correlation between the biomarkers of exposure (EROD and GST), biomarkers of effect (histopathology), and PAHs concentrations in the sediments.

Abstract:Phosphate behaviour in natural estuarine systems can be studied by performing field measurements and by undertaking laboratory simulation experiments. Thus, in this paper we describe the use of a dynamic automated estuarine simulator to characterize the geochemical reactivity of phosphate in varying salinity gradients in order to study possible mechanisms of phosphate removal from the dissolved phase (e.g. formation of some kind of apatite) and how changes in pH and salinity values influence this removal. Six laboratory assays, representing various salinity and pH gradients (average pH values between 7 and 8), were carried out. The geochemical equilibrium model MINTEQA2 was employed to characterize removal of phosphate. Among the minerals from which dissolved phosphate can originate, it seems that hydroxyapatite is by far the mineral that shows the greatest saturation indexes in the experiments. Thus, there is evidence that a type of calcium phosphate (hydroxyapatite) is involved in phosphate removal in the assays. Phosphate removal by Ca 2C occurs sharply at salinity values of 1-2, whereas by Fe 3C it is relatively gradual, at least until a salinity value of 7.

Petroleum hydrocarbon contamination of harbor sediments from shipping activity, fuel oil spills, and runoffs are becoming a great concern because of the toxicity and recalcitrance of many of the fuel components. Polycyclic aromatic hydrocarbons (PAHs) are of most concern due to their toxicity, low volatility, resistance to degradation, and high affinity for sediments. Microorganisms, especially bacteria, play an important role in the biodegradation of these hydrocarbons. The objective of the present study was to characterize and isolate PAH-(naphthalene) degrading bacteria in the coastal sediments of Cadiz (SW Spain), since this area is mostly polluted by PAH occurrence. A total of 16 naphthalene-utilizing bacteria were isolated from these sites. Introduction of bacteria isolated from contaminated sediments into mineral medium contributed to the increased rate of hydrocarbon utilization. The bacterial isolates obtained from these sites are very potent in utilizing naphthalene and crude oil. It would be interesting to assess if the selected naphthalene-degrading isolates may degrade other compounds of similar structure. Hence these isolates could be very helpful in bioremediating the PAH-contaminated sites. Further pursue on this work might represent eco-friendly solution for oil contamination on sea surface and coastal area.

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