Sublethal responses in caged organisms exposed to sediments affected by oil spills

This study was performed to determine sublethal responses of two invertebrate species by using field deployments in areas affected by oil spills, which are acute in the Galician Coast (NNW, Spain) and chronic in the Bay of Algeciras (SSW, Spain). The organisms employed were the crab Carcinus maenas and the clam Ruditapes philippinarum, and during 28 days the animals were exposed to contaminated sediments in cages under field conditions. Different biomarkers of exposure were determined after a 28-day period exposure: ethoxyresorufin O-deethylase (EROD), phase I detoxification enzyme, glutathione-S-transferase (GST) phase II detoxification enzyme but also implicated in oxidative stress events, glutathione peroxidase (GPX) and glutathione reductase (GR), both antioxidant enzymes. In addition, histopathological effects in target tissues of the deployed organisms were evaluated. Biomarker measurements were linked with the concentration of chemicals in the sediments in order to elucidate the type, source and bioavailability of contaminants that produce adverse effects in the bioindicator species. Results obtained in this study have shown how the application of the selected battery of biomarkers under field bioassays allows for the identification of alternative sources of stress that are not observable in laboratory experiments.     

Ca-Mg kutnahorite and struvite production by Idiomarina strains at modern seawater salinities

The production of Mg-rich carbonates by Idiomarina bacteria at modern seawater salinities has been investigated. With this objective, four strains: Idiomarina abyssalis (strain ATCC BAA-312), Idiomarina baltica (strain DSM 15154), Idiomarina loihiensis (strains DSM 15497 and MAH1) were used. The strain I. loihiensis MAH1 is a new isolate, identified in the scope of this work. The four moderately halophilic strains precipitated struvite (NH4MgPO4 x 6H2O) crystals that appear encased by small Ca-Mg kutnahorite [CaMg(CO3)2] spheres and dumbbells, which are also regularly distributed in the bacterial colonies. The proportion of Ca-Mg kutnahorite produced by the bacteria assayed ranged from 50% to 20%, and I. abyssalis also produced monohydrocalcite. All precipitated minerals appeared to be related to the bacterial metabolism and, consequently, can be considered biologically induced. Amino acid metabolism resulted in a release of ammonia and CO2 that increase the pH and CO(3)(2-) concentration of the culture medium, creating an alkaline environment that favoured carbonate and struvite precipitation. This precipitation may be also related to heterogeneous nucleation on negatively charged points of biological structures. Because the nature of the organic matrix determines which ion is preferentially adsorbed and, consequently, which mineral phase is formed, the uniquely high content in odd-iso-branched fatty acids of the Idiomarina suggests that their particular membrane characteristics could induce Ca-Mg kutnahorite production. The Ca-Mg kutnahorite, a mineral with a dolomite-ordered structure, production at seawater salinities is noticeable. To date, such precipitation in laboratory cultures, has only been described in hypersaline conditions. It has also been the first time that biomineralization processes have been related to Idiomarina bacteria.     

Accumulation and histopathological damage in the clam Ruditapes philippinarum and the crab Carcinus maenas to assess sediment toxicity in Spanish ports

The degree of contamination and toxicity in sediment from four Spanish ports (Cádiz, Huelva, Pasajes and Bilbao) was assessed in the present study. Two marine invertebrate species, the shore crab Carcinus maenas and the clam Ruditapes philippinarum, were exposed to the different sediments under laboratory conditions for 28 days. Relationships were developed among metal contamination (As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) in sediments, metal accumulation in gill tissues and histopathological lesions in different biological tissues to assess sediment toxicity. A multivariate analysis approach was used to calculate sediment quality guidelines (SQGs) by linking metal concentration in sediments with histopathological lesions measured in the exposed organisms. The results showed significant contaminant accumulation and histopathological lesions due to As, Pb and Zn in sediments at the port of Huelva; As, Cr, Cu, Hg and Ni at the ports of Pasajes and Cádiz; and Cr and Hg at the port of Bilbao. The link between chemical concentration in sediments and histopathological lesions allowed the determination of SQGs for the chemicals As, Cd, Cu, Cr, Hg, Ni and Zn.     

Sonophotocatalytic degradation of alazine and gesaprim commercial herbicides in TiO2 slurry

The photocatalytic degradation of alazine and gesaprim commercial herbicides was carried out in aqueous TiO(2) suspensions under UV light (15W, 352 nm). Degradation of these herbicides was also observed by the combined effects of photocatalysis with sonolysis (sonophotocatalysis) using an ultrasound source of 20kHz. Degradation profiles were recorded by measuring the concentration of the active compounds present in the alazine (alachlor and atrazine) and gesaprim (atrazine) by HPLC as a function of irradiation time (sound and/or light). Over 90% of the active component in the gesaprim was abated and those in alazine were completely degraded. The content of total organic carbon and chemical oxygen demand was also monitored. Mineralization of the commercial herbicides was achieved. Over 80% of chemical oxygen demand abatement was attained for both herbicides with sonophotocatalysis at 150 min of irradiation time. The photocatalytic degradation of the herbicides followed a pseudo-first order kinetics and their rate constant was increased by the combined effects of sonolysis.     

Preparation and characterization of carbon-enriched coal fly ash

Carbon-enriched fractions have been obtained from two coal fly ash (FA) samples. The FA came from two pulverized-coal fired power stations (Lada and Escucha, Spain) and were collected from baghouse filters. Sieving was used to obtain carbon-enriched fractions, which were further subjected to two beneficiation processes: acid demineralization using HCl and HF, and oil agglomeration using soya oil-water. Yield in weight after sieving, unburned carbon content, and several physicochemical characteristics of the obtained fractions were used to compare the performance of the beneficiation methods. Low carbon concentration was obtained by sieving, particularly in the case of Escucha FA. However, after acid demineralization or oil agglomeration, fractions containing unburned carbon in a range of 63% to 68% were obtained. These fractions showed differences in mineral phase composition and distribution depending on the FA and on the beneficiation method used. The textural properties of the obtained fractions varied as a function of their carbon content and the beneficiation method used. However, no significant differences in morphology of the carbonaceous particles were found.     

Prediction of CO maximum ground level concentrations in the Bay of Algeciras, Spain using artificial neural networks

The region of the Bay of Algeciras is a very industrialized area where very few air pollution studies have been carried out. The main objective of this work has been the use of artificial neural networks (ANNs) as a predictive tool of high levels of ambient carbon monoxide (CO). Two approaches have been used: multilayer perceptron models (MLPs) with backpropagation learning rule and k-Nearest Neighbours (k-nn) classifiers, in order to predict future peaks of carbon monoxide. A resampling strategy with twofold cross-validation allowed the statistical comparison of the different topologies and models considered in the study. The procedure of random resampling permits an adequate and robust multiple comparisons of the tested models and allow us to select a group of best models.     

Hydroxycinnamic acid derivatives in an aquatic liverwort as possible bioindicators of enhanced UV radiation

We examined, under laboratory conditions, the physiological responses of the aquatic liverwort Jungermannia exsertifolia subsp. cordifolia to artificially enhanced ultraviolet (UV) radiation for 82 days, especially considering the responses of five hydroxycinnamic acid derivatives. This species lives in mountain streams, where it is exposed to low temperatures and high UV levels, and this combination is believed to increase the adverse effects of UV. Enhanced UV radiation hardly caused any change in several physiological variables indicative of vitality, such as Fv/Fm and chlorophylls/phaeopigments ratio (OD430/OD410). Thus, this liverwort seemed to be tolerant to UV radiation, probably due to the accumulation of three UV-absorbing hydroxycinnamic acid derivatives: p-coumaroylmalic acid, 5'-(7',8'-dihydroxycoumaroyl)-2-caffeoylmalic acid, and 5'-(7',8'-dihydroxy-7-O-beta-glucosyl-coumaroyl)-2-caffeoylmalic acid. These compounds might serve as bioindicators of enhanced UV radiation.     

Highly charged swelling mica reduces Cu bioavailability in Cu-contaminated soils

This is the first test of a highly charged swelling mica's (Na-2-mica) ability to reduce the plant-absorbed Cu in Cu-contaminated soils from Chile. Perennial ryegrass (Lolium perenne L.) was grown in two acid soils (Sector 2: pH 4.2, total Cu = 172 mg Cu kg⁻¹ and Sector 3: pH 4.2, total Cu = 112 mg Cu kg⁻¹) amended with 0.5% and 1% (w/w) mica, and 1% (w/w) montmorillonite. At 10 weeks of growth, both mica treatments decreased the shoot Cu of ryegrass grown in Sector 2 producing shoot Cu concentrations above 21-22 mg Cu kg⁻¹ (the phytotoxicity threshold for that species), yet the mica treatments did not reduce shoot Cu concentrations when grown in Sector 3, which were at a typical level. The mica treatments improved shoot growth in Sector 3 by reducing free and extractable Cu to low enough levels where other nutrients could compete for plant absorption and translocation. In addition, the mica treatments improved root growth in both soils, and the 1% mica treatment reduced root Cu in both soils. This swelling mica warrants further testing of its ability to assist re-vegetation and reduce Cu bioavailability in Cu-contaminated surface soils.     

Pilot survey monitoring pharmaceuticals and related compounds in a sewage treatment plant located on the Mediterranean coast

A one-year monitoring study was performed to evaluate the occurrence, persistence and fate of a group of 14 organic compounds in a sewage treatment plant (STP) located in the south of Spain. These results are part of a more extensive study, financed by the Spanish Ministry of Research with the aim to evaluate the traceability of new pollutants on the Mediterranean coast and to determine the removal efficiency of sewage treatment plants (STP) for these pollutants. The compounds which have been analyzed include pharmaceuticals of various therapeutic categories (ibuprofen, acetaminophen, dipyrone, diclofenac, carbamazepine and codeine), pesticides (chlorfenvinfos and permethrin), caffeine, triclosan, bisphenol A and three of their more relevant metabolites (1,7-dimethylxanthine, carbamazepine 10,11-epoxide and 2,7/2,8-dichlorodibenzo-p-dioxin). An SPE/GC-MS multi-residue analytical method was developed and validated to facilitate simultaneous determination of these compounds in both influent and effluent wastewater. The method provided mean recoveries higher than 75%, with the exception of 2,7/2,8-dichlorodibenzo-p-dioxin, dipyrone and permethrin which exhibited recoveries lower than 22%. The overall variability of the method was below 14%. The method detection limit (LOD) was between 1 and 100 ng l(-1) and precision, which was calculated as relative standard deviation (RSD), ranged from 1.8% to 11.2%. The application of the proposed method has allowed the identification of all the target compounds at mean concentrations which ranged from 0.12 to 134 microg l(-1) in the influent and from 0.09 to 18.0 microg l(-1) in the effluent. The removal efficiencies of the STP for these compounds varied from 20% (carbamazepine) to 99% (acetaminophen), but in all cases resulted insufficient in order to avoid their presence in treated water and subsequently in the environment.