Degradation In Seawater Research Articles

Anti-biofouling by degradation of polymers

Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer (PEOCA) were synthesized, and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D). It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains. Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.

Both Cycloclasticus spp. and Pseudomonas spp. as PAH-degrading bacteria in the Seine estuary (France)

Like other highly urbanized and industrialized estuaries, the Seine estuary (France) has, for decades, received high inputs of polycyclic aromatic hydrocarbons (PAHs). In order to estimate the bioremediation potentials and to identify the bacterial species involved in hydrocarbon degradation, we used microcosms containing seawater from the Seine estuary supplemented with either naphthalene, phenanthrene, fluorene or pyrene. In the microcosms enriched with naphthalene or phenanthrene, hydrocarbon biodegradation was significant within 9 weeks (43% or 46%, respectively), as shown by analyses in GC-MS. In similar microcosms incubated also with naphthalene or phenanthrene, analysis of the 16S rRNA gene sequences (DNA and cDNA) with denaturing gradient gel electrophoresis and clone libraries indicated that the PAH-degrading communities were dominated by Cycloclasticus spp., confirming their universal key role in degradation of low-molecular-weight PAHs in marine environments. However, in contrast to previous studies, we found that Pseudomonas spp. also degraded naphthalene and phenanthrene in seawater; this occurred only after 21 days, as was confirmed by real-time PCR. Although this genus has been abundantly described in the literature as a good PAH-degrading bacterial group in soil or in sediment, to our knowledge, this is the first evidence of a significant fitness in PAH degradation in seawater.

Degradacja materialow polimerowych pochodzenia naturalnego w srodowisku wody morskie

The presented investigations covered environmental degradation of polymer materials (thermoplastic starch, modified cellulose and two types of starch-cellulose composites) in The Baltic Sea at Nordic Wharf of Gdynia harbor. Degradation process was also tested in laboratory conditions in sea water with sodium azide (NaN3, eliminating the microorganisms activity) added. These tests let evaluate the part of chemical hydrolysis in the process of degradation in natural sea environment. During samples' incubation (from 14 to 336 days) the following characteristic parameters of sea water were inspected: temperature, pH, oxygen content, chlorides' content and salinity (Table 1). The progress of environmental degradation of polymeric materials has been evaluated on the basis of weight loss (Fig. 5-7), changes of the surface (Fig. 1-4) as well as changes of the structure of the material, observed microscopically (Fig. 8-10). It was found that in the natural environment of sea water the enzymatic hydrolysis of the tested materials occurred, what was demonstrated by clear erosion of the surface and weight loss. The samples of modified cellulose were more susceptible to attacks of microorganisms living in sea water than the samples of thermoplastic starch. In case of composites more distinct weight changes were observed for material A (film form) than for B one (sheet form) because of large surface development at phase boundary. Their degradation in sea water is of enzymatic character and first the amorphous phase is degraded then the crystalline one.

Comparative hydrolysis and photolysis of four antibacterial agents (oxytetracycline oxolinic acid, flumequine and florfenicol) in deionised water, freshwater and seawater under abiotic conditions

A large fraction of antibacterial agents administered to farmed fish is released into the environment, either in leaching from uneaten medicated pelleted feed, or through urinary, branchial and faecal excretions. Processes such as hydrolysis and photolysis might be important for the elimination of antibacterial agents from water. The aim of the present study was to compare hydrolysis and photolysis of oxytetracycline (OTC), oxolinic acid (OXA), flumequine (FLU) and florfenicol (FLO) in three types of water (deionised water, freshwater and seawater) under abiotic conditions. For each antibacterial agent, a 7-day factorial experiment was designed in order to study the effect of light, pH and dissolved oxygen on hydrolysis and photolysis in deionised water. Furthermore, 14-day kinetics experiments were performed for each antibacterial agent and each type of water. FLO was not degraded by hydrolysis or photolysis phenomena. Hydrolysis phenomena only concerned OTC and were responsible for about 20% of its degradation following a 14-day exposure at a temperature of + 8 °C. Photolysis was responsible for about 70% of the OTC degradation in freshwater and seawater and 10% of the OXA and FLU degradation in seawater following the same exposure. Water pH played a role in OTC hydrolysis and photolysis. There was no close connection between OTC hydrolysis and photolysis and OTC binding to cations and organic matter, but it would be suggested that there was a connection between absence of OXA and FLU photolysis and OXA and FLU binding to organic matter.

Enzymatyczna i hydrolityczna degradacja poli(e-kaprolaktonu) w warunkach naturalnych

The studies on environment degradation of poly(e-caprolactone) (PCL) in various natural conditions namely in the compost with activated sludge and in seawater were done. Poly(e-caprolactone) degradation has been also carried out in laboratory conditions in seawater with sodium azide addition (NaN3, 0.195 g/L). NaN3 eliminated the activity of microorganisms what allowed evaluation of chemical hydrolysis part in the process of degradation in seawater. Enzymatic and chemical hydrolyses in the process of environmental degradation of PCL were evaluated based on the changes of: sample weight (Table 4), molecular weight of the polymer (Table 5) and the surface structure (Fig. 1). Effects of temperature, pH of environment and activities of dehydrogenases in the compost (Table 1-3) on the course of the process studied were determined. PCL sensitivity to biological decomposition has been confirmed. It was found that PCL degradation in the environments studied was a result of both enzymatic and chemical hydrolyses and enzymatic hydrolysis play the key role in the process.

Bisphenol A degradation in seawater is different from that in river water

The purpose of this study was to identify a relationship between changes of bacterial counts and bisphenol A (BPA) degradation in seawater under aerobic or anaerobic conditions, and at temperatures of 4, 25, and 35 °C. Water samples (seawater and river water) spiked with 1000 ng/ml of BPA was placed for 60 d. The BPA from water samples was extracted by OASIS HLB cartridges and was detected by high-performance liquid chromatography with fluorescence detection. BPA in river water was degraded under aerobic conditions and was below a detection limit (0.5 ng/ml) on the seventh day at both 25 and 35 °C. The more the level of bacterial counts increased, the more BPA degradation decreased. In the case of seawater samples, there was no relationship between BPA degradation and the change of bacterial counts. Bacterial counts at 25 and 35 °C increased rapidly at 5 and 3 d, respectively, but decreased since then. The concentration of BPA was not changed for 30 d at both 25 and 35 °C, but decreased from 40 to 60 d in spite of low levels of bacteria. These results show that the different degradation way for BPA in seawater may exist. Moreover, our study suggest that BPA in seawater than in river water can continue for longer time with no degradation and the possibility of BPA contamination on a marine organism can be higher than that on freshwater organism.

Evaluation of thick organic coatings degradation in seawater using cathodic protection and thermally accelerated tests

Organic coatings are often associated with cathodic protection to fight against the corrosion of metallic structures when immersed in seawater. However, cathodic protection leads to the generation of a strong alkalinity at the metal/coating interface, which causes the degradation of the coating. It is then necessary to develop a reliable method to evaluate the compatibility between organic coatings and the application of cathodic protection. On one hand, cathodic disbonding tests (ASTM G-8 and G-80) can be driven with an artificial defect but this defect is mainly responsible for the electrochemical response. In addition, calcareous deposit rapidly forms onto the defect zone when cathodic protection is applied which can make difficult the evaluation of coating delamination. On the other hand, immersion of defect-free specimens requires very long testing periods (several months or even years) in order to detect the coating degradation. In this work, an attempt to accelerate the coatings degradation by imposing a high temperature and thermal cycles were made in order to decrease the test-time duration. The influence of the applied cathodic potential was also investigated. The coating degradation was evaluated by EIS, considering the defect-free zone of coatings. It was shown that the coating degradation is faster in the presence of a defect and for high temperature (45 °C). Moreover, thermal cycles allow to greatly accelerate the degradation of defect-free coatings and then to compare the compatibility of both coatings with cathodic protection.

Inhibition of seawater on bisphenol A (BPA) degradation by Fenton reagents

To investigate bisphenol-A (BPA) degradation in seawater using Fenton reagents, changes in the BPA recovery and in the concentration of BPA metabolite, BPA- o-quinone in the three water samples; BPA free deionizad water (control water), 3% aq. NaCl and seawater as a function of time after BPA fortification in the presence of radical oxygen species (ROS) at 20 °C were investigated. The BPA recoveries were lower in both 3% aq. NaCl and seawater than in the control water. The BPA recovery in aq. NaOCl decreased as a function of NaOCl concentration, indicating that BPA could be degraded by the potent radical ion (OCl −) at the concentration of above 2 μM. A BPA metabolite, BPA- o-quinone was formed in all the water samples after addition of ROS which was produced by Fenton reaction (reaction of 0.11 M H 2O 2 and 0.44 mM FeCl 3·6H 2O). These results indicated that BPA degradation could occur by an addition of ROS and further accelerated by the formation of OCl − in salt containing water samples. BPA recovery was the highest in seawater immediately after addition of Fenton reagents and the amount of BPA- o-quinone was very low, which suggests that seawater possesses an inhibitory system on BPA degradation. There was a positive correlation ( p<0.01) between the fortified iron concentration and turbidity in seawater. Turbidity might be originated from iron-binding substances. Degradation threshold of BPA was observed when Fenton reaction was employed in seawater fortified with high amount of BPA. The present study suggested that iron trapping caused an inhibition on BPA degradation by Fenton reagents.

A Study of Oil Biodegradation in the Black Sea Water

A laboratory study was conducted to examine oil biodegradation in the presence of a fouling organism community. It is shown that the majority of fouling species exhibit relatively weak tolerance to oil. Oil degradation in seawater is shown to proceed quicker and more completely in the presence of the fouling organism community than it does without such organisms. The population of specific bacterial groups is shown first to grow and next decrease as a result of accumulation in water of toxic products of their vital activity. Oil biodegradation is found to cause substantial changes in the water hydrochemical characteristics in experimental vessels.

Evaluation of ozone depletion potentials for chlorobromomethane (CH 2ClBr) and 1-bromo-propane (CH 2BrCH 2CH 3)

Chlorobromomethane (CH 2CIBr) and 1-bromo-propane (CH 2BrCH 2CH 3 or simplified as 1 - CH 3H 7Br) are being considered for use as solvents and potentially in other applications. As with other chemicals that contain chlorine and/or bromine, it is important to determine the potential environmental effect from use and emissions of such compounds, including effects on stratospheric ozone. In this paper, the Ozone Depletion Potentials (ODPs), an important measure of the potential effects on ozone, are evaluated for these two compounds using our two-dimensional chemical-transport model of the troposphere and stratosphere. This is the first time these compounds have, to our knowledge, been evaluated with atmospheric models. Our model results show that the main removal process ( ca. 99%) in the atmosphere for these compounds is the reaction with OH radicals. Photolysis has only a minor (⩽ 1 %) effect on the atmospheric lifetimes of either compound. The atmospheric lifetimes of CH 2ClBr and 1 - C 3H 7Br due to atmospheric reactions are evaluated to be 0.40 yr (146 d) and 0.03 y (11 d), respectively. However, oceanic losses are likely to be important for CH 2ClBr. Because of limited data on solubility and degradation in sea water, the lifetime for ocean loss currently has a range of 0.43-0.65 yr. This results in a total lifetime for CH 2CIBr of 0.21-0.25 yr. An ocean sink for 1 - C 3H 7Br is likely to have an insignificant effect on its atmospheric lifetime or ODP. The ODP for 1 - C 3H 7Br is evaluated to be 0.006, while the ODP for CH 2 ClBr including the effects of the ocean sink is 0.11–0.13. There are additional uncertainties in these values due to ambiguities in measured reaction rates and in the model treatment of atmospheric processes.

On the degradation of methyl bromide in sea water

Methyl bromide degradation in sea water can be described by a summation of the hydrolysis and chloride ion exchange reactions. Laboratory experiments covered chloride concentrations of 0.1 to 1.0 mol/1, and temperatures from 20 to 60°C. The first‐order hydrolysis rate constant is and the second‐order chloride ion exchange rate constant deduced from the experiments is At a sea water surface temperature of 21.9 °C and a chloride concentration of 0.56 mol/1, the calculated degradation half‐life of methyl bromide in sea water is 4 days. At 35 °C, τ1/2 = 22 hr.

The effect of Cu on gill and esophagus lipid metabolism in the rainbow trout Oncorhynchus mykiss

Rainbow trout Oncorhynchus mykiss were exposed to 0, 100, 300 and 800 μgl −1 ambient Cu in brackish water (BW) for 4 days at 13 °C and subsequently transferred to either clean BW, clean fresh water (FW) or clean seawater (SW) at 16 °C. After incubation with 32P-phosphate and 14C-acetate added as precursors to the water the fish showed a degradation, depending on previous [CU], of 32P- and 14C-labelled gill membrane phospholipids if they had been transferred to SW or remained in BW. Corresponding experiments where the fish were exposed to Cu in BW for 12 days showed a similar subsequent degradation in SW and BW of both gill and esophagus membrane phospholipids, however to a much lesser degree in gill tissue than after 4 days. Plasma Na + was similarly reduced by up to 8%, depending on previous ambient Cu, but in this case only after transfer to FW and only after 4 days of exposure. Both the effect on membrane lipid metabolism and plasma Na + thus showed acclimation to ambient Cu but there was apparently no direct correlation between the two different types of observed changes in membrane function.

The dissolution and photodegradation of Kuwaiti crude oil in seawater. Part 2: A laboratory photodegradation apparatus and photodegradation kinetics of a model seawater soluble hydrocarbon (phenanthrene)

A laboratory photodegradation apparatus, incorporating a calibrated xenon lamp, controlled temperature unit and quartz reaction cells designed to simulate natural irradiation by sunlight, and which is suitable for kinetic studies of hydrocarbon degradation in seawater, is described. The apparatus and experimental method was used to determine the pseudo-first order photodegradation constant (k p) of phenanthrene (a component present in the seawater-soluble fraction of crude oil) in seawater at 25 °C. The k p values determined in duplicate experiments were −0.342 ± 0.003 and −0.317 ± 0.029 h −1 with half-lives ( t 1 2 ) of 2.03 and 2.19 h. Extrapolation to natural sunlight at latitude 30 °N (Florida midday, midsummer assuming 12 h daylight) gave t 1 2 values of 8.6–9.5 h, suggesting that photodegradation is a significantly fast reaction for removal of phenanthrene from seawater under some conditions. Gas chromatography-mass spectrometry (GC-MS) and ultraviolet fluorescence spectrophotometry were both suitable methods for monitoring the degradation, but GC-MS was most suitable for the determination of photoproducts. The identifiable products amounted to some 12% of the total products after 7 h irradiation, and their distribution was consistent with a known mechanism of phenanthrene degradation involving formation of an unstable and reactive 9,10-epoxide. The photolysis method should prove valuable for the determination of k p and t 1 2 values for a wide range of petroleum hydrocarbons in seawater.

On the photolysis of selected pesticides in the aquatic environment

The photodegradation (UV λ > 290nm) of the herbicides atrazine and diuron was examined in distilled water and artificial seawater containing humic acids. Major photodegradation products were hydroxyatrazine and monuron, respectively. The results showed a faster degradation in seawater as compared to distilled water for atrazine whereas for diuron a quenching effect was observed thus retarding photodegradation. The photodegradation of fenitrothion was also investigated. For this pesticide, the hydrolysis predominates in seawater whereas the photolysis is very slow in distilled water, so that acetone was needed as photosensitizer. The advantages of direct analysis of water samples by liquid chromatography with diode array and mass spectrometric detection is illustrated.

Utilisation of liquid chromatography in aquatic photodegradation studies of pesticides: A comparison between distilled water and seawater

The advantages of liquid chromatography with diode array and mass spectrometric detection are described for the direct characterization of the photodegradation products of Fenitrothion, Atrazine and Diuron in distilled water and artifical seawater samples. The photodegradation (UV λ>290 nm) of the herbicides Atrazine and Diuron was examined in distilled water and in artificial seawater containing humic acids. Major photodegradation products were hydroxyatrazine and Monuron, respectively. The results showed a faster degradation in seawater as compared to distilled water for Atrazine whereas for Diuron a quenching effect was observed thus retarding photodegradation. The photodegradation of Fenitrothion was also investigated. For this pesticide, hydrolysis predominates in seawater and photolysis is very slow in distilled water, so that acetone was needed as photosensitizer.

124Sn as a Tracer of tributyltin degradation in seawater

This is the first demonstration of the stable isotope 124Sn as a tracer of tributyltin (Bu 3 124Sn) degradation. Gas chromatography-mass spectrometry (GC-MS) was used to determine the labeled parent compound and its degradation products, labeled dibutyltin (Bu 2 124Sn) and (mono)butyltin (Bu 124Sn). This method verified that resident marine microbes degraded Bu 3 124Sn in seawater during 6-day exposures in late summer. Degradation was enhanced by addition of nutrients, and was impeded by total darkness and by laboratory ambient lighting and/or temperature. Increases in Bu 3 124Sn concentration inhibited natural primary production, but in general, led to increased bacterial growth during bottled experiments. We also discovered that some analytical methods can lead to erroneous conclusions about Bu 3 Sn degradation.

EFFECT OF TEMPERATURE ON KINETIC OF ANIONIC SURFACTANT DEGRADATION IN SEA-WATER

ABSTRACT This paper studies the effect of temperature on the velocity of degradation of a commercial surfactant (LAS) in sea-water. The tests were conducted in conditions designed to simulate those in which anionic surfactant matter is dumped into the Bay of Cadiz. A comparison is made between the results of surfactant degradation in sea-water only and degradation and sea-water in the presence of marine sludge. Temperature is found to exert a profound effect on the degradation process; at temperature below 5-10°C there was no appreciable decomposition of the surfactant, while at high temperatures, 20-25°C, degradation was practically complete after 21 days of testing. In addition, were sludge was added degradation was faster at all temperatures studied. As a prior step, a method was divised to extract the surfactant contained in the sludge.

Evidence for rapid degradation of tributyltin in a marina

Tributyltin (TBT) was found to degrade rapidly to dibutyltin (DBT) in a marina where high TBT concentrations have been reported. In a die-away experiment the half-life of TBT in water from this marina was six days. The half-life of 14C-TBT (2 μg l −1) added to yacht basin water was 6 and 7 days in the light and dark, respectively. The principal TBT metabolite was dibutyltin (DBT) with slower formation of monobutyltin (MBT) and 14CO 2. Microbial degradation appears to be the primary process accounting for TBT degradation in seawater.

The toxicity, absorption and excretion of rotenone in oysters ( Ostrea edulis), and its degradation in seawater at temperatures near 0°C

A rapid extraction procedure and a HPLC method for quantitative measurements of the concentration of rotenone in oysters ( Ostrea edulis) and in seawater is presented. The absorption rate of rotenone by oysters was rapid. With an average rotenone concentration in the seawater of 26 ppb, the concentration in the oysters reached 4.6 ppm after 4 days of exposure. The t 1 2 of the excretion of rotenone was 40 h at 10°C. The absorption rate was highly affected by both the rotenone concentration in the seawater and the seawater temperature. Rotenone was quite stable in seawater at low temperatures. At an average temperature close to 0°C, 18% of the rotenone added was still present 45 days after preparing the solution (1 ppm Gullviks rotenone mixture) in seawater. The acute mortality observed was closely related to the measured concentration of rotenone in the oysters.

Proteolytic activity in coastal oceanic waters: depth distribution and relationship to bacterial populations

Proteolytic activity and the role of bacteria in protein degradation in seawater were investigated during 2 cruises to the Santa Monica Basin. The rate of hydrolysis of L-leucyl-P-naphthylaniine was used as a measure of proteolytic activity, and was compared with bacterial numbers, production, and growth rates throughout the water column (905 m max. depth). Peak proteolytic activities in the upper 100 m of the water column were more than 10 times those of deeper waters, though the natural substrate concentrations (combined hydrolyzable amlno acids) in the Santa Monica Basin have prev~ously been found to vary by only 3 to 4-fold Sediment porewaters were assayed during one cruise and found to have 20 to 30 times more proteolytic activity than the peak water column samples from the same cruise, though the origin of this activity could not be determined. Most of the proteolytic activity in the water column was associated with particles the size of bacteria (0.2 to 0.8 pm) and, overall, total proteolytic activity was highly correlated with all bacterial variables tested. However, the average activities per cell were not related to average cell sizes, suggesting that proteolytic activity is not s~mply a function of bacterial biomass. In samples from one of the crulses, the average activities per cell covarled with bacterial growth rates (thymidme incorporation per cell), but this was not true for samples taken during the second cruise. Laboratory expenments using 'seawater cultures' indicated that neither changes in cell size nor growth rate alone could account for changes in the amount of proteolytic enzyme expressed by marine bacteria. These results suggest that proteolytic activity in the water column is primarily associated with bacteria and is likely to be controlled by a number of factors related to the bacterioplankton, including biomass and growth rates.