RESUMO
Aerobic biodegradation of linear alkylbenzene sulfonates (LAS) and sulfophenylcarboxylic acids (SPCs) in water, at different salinity values, has been studied. Three experiments have been carried out employing a staircase model system with continuous dosage of LAS to the system and using concentrations of LAS of the same order as those detected in littoral waters receiving urban wastewater discharges. LAS biodegradation was observed to be almost complete (showing a great extent), and in all cases exceeds 98.4%. At the very low concentration values of LAS utilized in the experiments, no significant variations in the biodegradation of LAS due to the effect of the different salinity values assayed were observed. The biodegradation intermediates detected for all the cases were sulfophenylcarboxylic acids with carboxylic chains of between five and 13 carbon atoms. The detection of C13-SPC (which is only produced by C13-LAS) confirms the existence of omega-oxidation. The total disappearance of SPCs in all cases indicates that mineralization of LAS at the concentrations tested was complete.
Assuntos
Aerobiose , Ácidos Alcanossulfônicos/metabolismo , Ácidos Carboxílicos/metabolismo , Cloreto de Sódio/metabolismoRESUMO
Surface sediment samples were analyzed for organotins namely tributyltin (TBT), dibutyltin and monobutyltin from six areas located in the Gulf of Cádiz (14 stations), Spain. The total butyltin ranged between undetected and 1,580 ng Sn g(-1). TBT generally prevailed in most of the samples, suggesting fresh inputs of butyltin compounds and/or less degradation of TBT. The observed levels of butyltins at several sites are much higher than that required to induce toxic effect on marine organisms, suggesting that these sediments are polluted with butyltin compounds. The clam Ruditapes philippinarum was used for studying bioaccumulation of butyltins by exposing them to contaminated sediments from the Gulf of Cádiz over a period of 28 days under laboratory conditions. Biota-sediment accumulation factor (BSAF) ranged from 0.44 to 3.99.
Assuntos
Compostos Orgânicos de Estanho/farmacocinética , Compostos de Trialquitina/farmacocinética , Poluentes Químicos da Água/farmacocinética , Animais , Oceano Atlântico , Bivalves/metabolismo , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Compostos Orgânicos de Estanho/química , Espanha , Compostos de Trialquitina/químicaRESUMO
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.
Assuntos
Bactérias/isolamento & purificação , Poluentes Ambientais/metabolismo , Sedimentos Geológicos/microbiologia , Naftalenos/metabolismo , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Biodegradação Ambiental , Contagem de Colônia Microbiana , Sedimentos Geológicos/química , EspanhaRESUMO
We describe the effect of heavy metals Zn, Cd, Pb and Cu on the induction of methallothioneins on the clam Scrobicularia plana along a salinity gradient simulated under laboratory conditions. The clams were exposed to constant heavy metal concentrations in a dynamic estuary simulator during a 15-day assay to investigate possible induction of metal-binding proteins in them. The concentration of heavy metals in water was analysed. Clams were analysed for methallothionein concentrations. The speciation of Zn, Cd, Pb and Cu along the salinity gradient was modelled. Zn showed the highest concentrations and its prevalent species was the free ion. Intersite differences have been observed in methallothionein concentration and related to the salinity gradient. It seems that synthesis of methallothioneins is the result of physiological forces acting in concert with the changes in the chemical speciation of metals, owing to the trace metals uptake is controlled by means of an interaction of physiology and physicochemistry.
Assuntos
Bivalves/metabolismo , Metalotioneína/biossíntese , Metais Pesados/toxicidade , Animais , Água Doce/análise , Regulação da Expressão Gênica/efeitos dos fármacos , Metais Pesados/análise , Metais Pesados/farmacocinética , Modelos Químicos , Água do Mar/análise , Cloreto de Sódio/análiseRESUMO
The spill at 'Los Frailes' caused a large input of metals into the riverine, estuarine and coastal ecosystems. Metal behaviour in natural waters can be studied both by performing field measurements, and by undertaking laboratory simulation experiments. Here is described the behaviour of the heavy metals Zn, Cd, Pb and Cu in the Guadalquivir estuary using incubation experiments and the results compared to those obtained during field assessments. If the toxic waste water had been discharged untreated into the environment, it could have raised the heavy metal concentrations in the estuary water to high values, such as 20.65 microM for Zn and 40 x 10(-3) microM for Cd. These values are several times higher than those obtained in samples collected in the area during the monitoring of the early impact. The metals present a non-conservative behaviour, with a high loss to waters of low salinity values.