Compounds In Seawater Research Articles

Adsorption and fractionation of Pt, Pd and Rh onto inorganic microparticles and the effects of macromolecular organic compounds in seawater

Adsorption and fractionation of Pt, Pd and Rh (defined here as platinum group elements, PGEs) onto the representative inorganic microparticles, including Fe2O3, MnO2, CaCO3, SiO2, Al2O3 and kaolinite in seawater were investigated. The effects of macromolecular organic compounds (MOCs) as the representatives of organic matter, including humic acids (HA), bovine serum albumin (BSA) and carrageenan, on the adsorption were also studied considering that organic matter is ubiquitous in seawater and indispensable to marine biogeochemical cycles. In the absence of MOCs, the representative mineral particles Fe2O3 and MnO2 had the strongest interaction with PGEs. The adsorption of PGEs onto the representative biogenic particles SiO2 and CaCO3 and lithogenic particles Al2O3 and kaolinite was similar or weaker than onto the mineral particles. MOCs inhibited the interaction between PGEs and the particles except for Pt and Pd onto the biogenic particles in artificial seawater. This impediment may be closely related to the interaction between particles, MOCs and elements. The partition coefficient (log Kd) of Pt was similar (∼4.0) in the presence of MOCs, indicating that the complexation between Pt and MOCs was less important than hydrolysis or adsorption onto the acid oxide particle surface. Rh tended to fractionate onto the mineral and lithogenic particles in the presence of HA and carrageenan, while Pd was more likely to fractionate onto the biogenic particles. However, BSA enhanced the fractionation tendency of Pd onto the mineral particles. The results indicate that the adsorption behavior of Pd onto inorganic particles was significantly affected by the composition or the type of MOCs. Hence, the interaction between PGEs and inorganic particles may be greatly affected by the macromolecular organic matter in the ocean.

Segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer for measurements of a broad range of volatile organic compounds in seawater

Abstract. We present a technique that utilises a segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer to measure a broad range of dissolved volatile organic compounds. Thanks to its relatively large surface area for gas exchange, small internal volume, and smooth headspace–water separation, the equilibrator is highly efficient for gas exchange and has a fast response time (under 1 min). The system allows for both continuous and discrete measurements of volatile organic compounds in seawater due to its low sample water flow (100 cm3 min−1) and the ease of changing sample intake. The equilibrator setup is both relatively inexpensive and compact. Hence, it can be easily reproduced and installed on a variety of oceanic platforms, particularly where space is limited. The internal area of the equilibrator is smooth and unreactive. Thus, the segmented flow coil equilibrator is expected to be less sensitive to biofouling and easier to clean than membrane-based equilibration systems. The equilibrator described here fully equilibrates for gases that are similarly soluble or more soluble than toluene and can easily be modified to fully equilibrate for even less soluble gases. The method has been successfully deployed in the Canadian Arctic. Some example data from underway surface water and Niskin bottle measurements in the sea ice zone are presented to illustrate the efficacy of this measurement system.

A fundamental study of chalcopyrite flotation in sea water using sodium silicate

Due to the shortage of fresh water, sea water has been considered as a promising alternative for mineral flotation. Sodium silicate (SS) was used to eliminate the negative influence due to the application of sea water for chalcopyrite flotation and the related mechanisms were studied. Flotation results showed that the most detrimental compound in sea water was the divalent ion of Mg2+. Contact angle measurements suggested that SS increased chalcopyrite hydrophobicity in sea water and MgCl2 solution. The zeta potential of chalcopyrite became more negative while that of Mg(OH)2 was reversed from positive to negative upon the addition of SS, preventing the adsorption of hydrophilic Mg(OH)2 precipitates on chalcopyrite surface. FTIR and XPS analyses further confirmed that the presence of SS in sea water reduced the adsorption of Mg(OH)2 on chalcopyrite surface. In addition, Derjguin-Landau-Verwey-Overbeek (DLVO) calculation indicated that SS can prevent the adsorption of Mg(OH)2 on chalcopyrite surface, thereby increasing chalcopyrite recovery. Therefore, this study presents an effective method to improve chalcopyrite flotation recovery in sea water.

Assessment of the Current State of the Caspian Sea and the Caspian Seal Habitat Analysis

This article is devoted to the determination of heavy metals and harmful organic compounds in sea water – the habitat of the Caspian seal. The group of the most common heavy metals, according to many authors, includes manganese, nickel, zinc, iron, cadmium, lead, copper and their salts, characterized by long-term preservation and accumulation in water, sediments and hydrobionts. The studies were conducted from February 7–12, 2017 on the route from the Kalamkas (Kazakhstan) field through the islands of Kulaly to the village of Bautino. Water samples were taken 10‒20 cm below the sea ice and surface level, each sample was taken in 2 replicates: one for the Kazakhstan laboratory in Almaty and one for the French independent laboratory. Water samples were analyzed for the content of 13 heavy metals such as – Co, Cu, Ti, Bi, Ag, V, Al, Be, Sb, Sn, Fe, Cr, Mo. It was established that in all water samples the content of vanadium exceeds the maximum permissible concentration (MPC) level by 1.5–7.4 times, beryllium ‒ 140–445 times, antimony 13.2–17.2 times. The maximum concentrations of the V and Be contents were found in water samples taken at sampling points No. 1 and 2, and Sb ‒ at points No. 1.6, 7.8. Cobalt, copper, iron and chromium were not detected in the samples presented. The content of other metals (Ti, Bi, Ag, Al, Sn, Mo) was significantly below the permissible levels or below the detection limits of the method. All samples of sea water are contaminated by several organic chemical pollutants, to various degrees and from different origins. Data on the accumulation of petroleum hydrocarbons and heavy metals in the habitat of Caspian seals characterize the toxicological situation in the study region.

The rise of oxygen-driven arsenic cycling at ca. 2.48 Ga

The Great Oxidation Event (GOE) at 2.45 Ga facilitated the global expansion of oxidized compounds in seawater. Here, we demonstrate that the GOE coincided with a sharp increase in arsenate and arsenic sulfides in marine shales. The dramatic rise of these oxygen-sensitive tracers overlaps with the expansion of key arsenic oxidants, including oxygen, nitrate, and Mn(IV) oxides. The increase in arsenic sulfides by at least an order of magnitude after 2.45 Ga is consistent with the proposed transition to mid-depth continental-margin sulfide-rich waters following the GOE. At the same time, the strong increase in arsenate content, to ∼60% of the total arsenic concentration in shales, suggests that the oxidative component of the arsenic cycle was established for the first time in Earth’s history. These data highlight the global emergence of a new selective pressure on the survival of marine microbial communities across the GOE, the widespread appearance of toxic, oxidized chemical species such as arsenate in seawater.

Domoic Acid-Producing Diatoms of the Genus Pseudo-nitzschia H. Peragallo, 1900 (Bacillariophyta) from the North Pacific

Information on diatoms of the genus Pseudo-nitzschia, known as producers of domoic acid (DA), from the North Pacific is summarized. The differences in the negative impact of toxic diatoms on ecosystems in the western and eastern North Pacific are shown. The possible causes that determine the degree of these different impacts are discussed: a different composition of dominant species; a difference in the intracellular DA concentration in bloom-forming species; the hydrological, climatic, and hydrochemical factors that are responsible for the formation of toxic blooms (upwelling events, patterns of water circulation, concentration of iron compounds in sea water, etc.). The conclusion is made that the prospects of further studies of toxic diatoms are based on comparative investigations into the species and genetic diversity of Pseudo-nitzschia and associated bacteria, as well as the environmental parameters that control the formation of toxic blooms and the accumulation of DA in microalgae and other marine organisms in the eastern and western North Pacific.

Evaluation of polar organic chemical integrative and hollow fibre samplers for the determination of a wide variety of organic polar compounds in seawater

The calibration of two passive samplers for the determination of 20 emerging organic compounds in seawater is described in this work: i) a new version of polar organic chemical integrative sampler (POCIS) containing 100 mg of mixed-mode anion exchanger (Strata X-AW) and 100 mg of polymeric HLB (Plexa) sorbent materials and using a highly porous Nylon membrane (30-μm pore size) and ii) polyethersulfone (PES) hollow fibre. Among the studied contaminants, herbicides, hormones, life style products (stimulants and artificial sweeteners), industrial chemicals (corrosion inhibitor and fluorinated compounds), personal care products and several pharmaceuticals were included. In the case of POCIS, both the sorbents and the Nylon membranes were extracted and analysed independently. The calibration set up consisted on a continuous-flow tank that was fed with a continuous flow of seawater (2 L/h) and a stock mixture of contaminants (20 mL/h), assuring a nominal concentration of ~ 600 ng/L (each analyte) in the tank. The uptake was linear in POCIS sorbent and Nylon membranes but exponential for PES hollow fibres. Furthermore, the highest sampling rates (Rs) values were obtained in POCIS sorbent (between 2.7 for acetaminophen and 491 mL/day for perfluoro-n-octanoic acid, PFOA) followed by Nylon membranes (between 3.6 for OBT and 50 mL/day for telmisartan) and the lowest were those from PES fibres (between 1.7 for bezafibrate and 157 mL/day for butylparaben). Additionally, five deuterated compounds ([2H5]-atrazine, [2H3]-amitriptyline, [2H7]-irbesartan, [2H3]-ketoprofen and [2H9]-progesterone) were studied as candidates for performance reference compounds (PRCs) in both POCIS and PES, and though [2H5]-atrazine, [2H9]-progesterone and [2H3]-amitriptyline showed acceptable results in the case of POCIS, only [2H5]-atrazine provided a good validation. In the case of PES fibres, the PRC corrections did not provide acceptable results due to a low dissipation of the PRCs. Finally, POCIS were deployed in two sites of the low part of the estuary of Bilbao (northern Spain) from where water samples were also taken and analysed. As a result, in addition to the overall good agreement between the passive and active samplings, passive samplers allowed the determination of several compounds that were below the detection limits in the active sampling.

Threat of plastic ageing in marine environment. Adsorption/desorption of micropollutants

Ageing of various plastics in marine environment was monitored after immersion of two synthetic (polyvinylchloride, PVC, and polyethylene terephthalate, PET) and one biodegradable (poly(butylene adipate co-terephtalate), PBAT) plastics for 502days in the bay of Lorient (Brittany, France). Data analysis indicates that aged PVC rapidly releases estrogenic compounds in seawater with a later adsorption of heavy metals; PET undergoes a low weakening of the surface whereas no estrogenic activity is detected; PBAT ages faster in marine environment than PVC. Aged PBAT exhibits heterogeneous surface with some cavities likely containing clay minerals from the chlorite group. Besides, this degraded material occasionally shows a high estrogenic activity. Overall, this study reports, for the first time, that some aged plastics, without being cytotoxic, can release estrogenic compounds in marine environment.

Analysis of lipophilic marine biotoxins by liquid chromatography coupled with high-resolution mass spectrometry in seawater from the Catalan Coast.

Marine biotoxins regularly occur along the coast, with several consequences for the environment as well as the food industry. Monitoring of these compounds in seawater is required to assure the safety of marine resources for human consumption, providing a means for forecasting shellfish contamination events. In this study, an analytical method was developed for the detection of ten lipophilic marine biotoxins in seawater: azaspiracids 1, 2, 3, 4 and 5, classified as azaspiracid shellfish poisoning toxins, and pectenotoxin 2, okadaic acid and the related dinophysistoxin 1, yessotoxin and homoyessotoxin, classified as diarrheic shellfish poisoning toxins. The method is based on the application of solid-liquid ultrasound-assisted extraction and solid-phase extraction, followed by high-performance liquid chromatography coupled with high-resolution mass spectrometry. The limits of detection of this method are in the range of nanograms per litre and picograms per litre for most of the compounds, and recoveries range from 20.5% to 97.2%. To validate the effectiveness of this method, 36 samples of surface water from open coastal areas and marinas located along the Catalan coast on the Mediterranean Sea were collected and analysed. Eighty-eight per cent of these samples exhibited okadaic acid in particulate and aqueous phases in concentrations ranging from 0.11 to 560 μg/g and from 2.1 to 1780 ng/L respectively. Samples from open coastal areas exhibited higher concentrations of okadaic acid in particulate material, whereas in samples collected in sportive ports, the particulate material exhibited lower levels than the aqueous phase. Graphical Abstract Biotoxins investigated in seawater of the Catalan coast.

Identification of organic compounds in ocean basement fluids

We have analyzed the dissolved organic carbon, OC, in ocean basement fluids using Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (FT-ICR-MS). The compounds identified at the two sites, near the Juan de Fuca and Mid-Atlantic Ridges (North Pond), differ substantially from each other and from seawater. Compared to Juan de Fuca, North Pond organics had a lower average molecular weight (349 vs. 372g/mol), 50% more identifiable compounds (2181 vs. 1482), and demonstrably lower average nominal oxidation state of carbon (−0.70 vs. −0.56). The North Pond fluids were also found to have many more N- and S-bearing compounds. Based on our data, the marine subsurface can alter the types of dissolved OC, DOC, compounds in seawater.

The influence of salt matrices on the reversed-phase liquid chromatography behavior and electrospray ionization tandem mass spectrometry detection of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid in water

The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography–heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI–MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na+, K+) or trivalent (Al3+, Fe3+) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu2+, Co2+, Zn2+, and Mn2+ prevented glyphosate detection whereas Ca2+, Mg2+, and Sr2+ altered the retention time. At certain tested concentrations of Ca2+ and Sr2+ glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca2+, Mg2+, and Sr2+ can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI–MS/MS analysis.

An approach to determination of phenolic compounds in seawater using SPME-GC-MS based on SWCNTs coating

Phenolic compounds have become one kind of the important pollutants of the marine environment. Single-walled Carbon nanotubes, as one-dimensional nano materials, have light weight and perfect hexagonal structure of connections, with many unusual mechanical, chemical and electrical properties. In recent years, with the research of carbon nanotubes and other nano materials, the application prospect is also constantly discussed. In this paper, homemade single-walled carbon nanotubes (SWCNTs) coating was used for establishing an analytical approach to the determination of five kinds of phenolic compounds in seawater using SPME-GC-MS. Optimal conditions: After saturation was conducted with NaCl, and pH was adjusted to 2.0 with H2SO4, the extract was immersed in a water bath at 40°C for GC-MS determination through 40-min agitating extraction at 500 rmin−1 and 3-min desorption at 280°C. The liniearities ranged between 0.01-100 μg L−1, and the determination limits ranged between 1.5-10 ng L−1. The relative standard deviation (RSD, n = 5) was less than 6.5%. For the phenolic compounds obtained from the spiked recovery test for actual seawater samples, the rates of recovery were 87.5%-101.7%, and the RSDs were less than 8.8%, which met the requirements of determination. Due to its simplicity, high efficiency and low consumption, this approach is suitable for the analysis of trace amounts of phenolic compounds in marine waters.

Trace analysis of butyltin compounds in seawater of some west Algerian harbors by gas chromatography-mass spectrometry

ABSTRACTAn analytical gas chromatography-mass spectrometry (GC-MS) method was investigated for the determination of trace butyltin compounds (BTs) (tributyltin [TBT] and its derivatives dibutyltin [DBT] and monobutyltin [MBT]) in seawater collected from some west Algerian harbors. BTs were detected in all samples from all investigated sites. Levels of total BT concentrations detected in seawater ranged from 0.045 to 0.798 μg Sn L−1. Higher concentrations of BTs were found in seawater collected from Bethioua (0.798 μg Sn L−1), an oil terminal, and Mers El Kébir shipyard (0,585 μg Sn L−1). This suggested that maritime activities close to the harbors play a major role as the source of BTs. Indeed, the harbor of Bethioua is frequented by many tankers. TBT was the predominant compound in seawater collected from almost all the sampling locations, indicating the fresh input of TBT in the harbors.

The Partial Molal Volumes and Compressibilities of Nonelectrolytes and Amino Acids in 0.725 m NaCl

The partial molal volumes and compressibilities of a number of nonelectrolytes and amino acids in 0.725 m NaCl have been determined from density and compressibility measurements. The results have been used to examine the behavior of these compounds in ocean waters. The partial molal volumes of the solutes in 0.725 m NaCl were a linear function of the values in water. The partial molal compressibilities of urea, sugars and amino acids were all negative due to the hydration of water molecules. The values of partial molal compressibilities in 0.725 m NaCl were not as negative due to the decrease in the hydration in the salt solution. A simple hydration model is used to estimate the number of water molecules hydrated to the solutes in 0.725 m NaCl. The partial molal volumes and compressibilities for the nonelectrolytes determined in this study should be useful in estimating the effect of pressure on equilibrium reactions of these compounds in seawater.

Multi-residue analysis of legacy POPs and emerging organic contaminants in Singapore's coastal waters using gas chromatography–triple quadrupole tandem mass spectrometry

A gas chromatography–triple quadrupole mass spectrometry (GC–MS/MS) based method was developed for determination of 86 hydrophobic organic compounds in seawater. Solid-phase extraction (SPE) was employed for sequestration of target analytes in the dissolved phase. Ultrasound assisted extraction (UAE) and florisil chromatography were utilized for determination of concentrations in suspended sediments (particulate phase). The target compounds included multi-class hydrophobic contaminants with a wide range of physical–chemical properties. This list includes several polycyclic and nitro-aromatic musks, brominated and chlorinated flame retardants, methyl triclosan, chlorobenzenes, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spiked MilliQ water and seawater samples were used to evaluate the method performance. Analyte recoveries were generally good, with the exception of some of the more volatile target analytes (chlorobenzenes and bromobenzenes). The method is very sensitive, with method detection limits typically in the low parts per quadrillion (ppq) range. Analysis of 51 field-collected seawater samples (dissolved and particulate-bound phases) from four distinct coastal sites around Singapore showed trace detection of several polychlorinated biphenyl congeners and other legacy POPs, as well as several current-use emerging organic contaminants (EOCs). Polycyclic and nitro-aromatic musks, bromobenzenes, dechlorane plus isomers (syn-DP, anti-DP) and methyl triclosan were frequently detected at appreciable levels (2–20,000pgL−1). The observed concentrations of the monitored contaminants in Singapore's marine environment were generally comparable to previously reported levels in other coastal marine systems. To our knowledge, these are the first measurements of these emerging contaminants of concern in Singapore or Southeast Asia. The developed method may prove beneficial for future environmental monitoring of hydrophobic organic contaminants in marine environments. Further, the study provides novel information regarding several potentially hazardous contaminants of concern in Singapore's marine environment, which will aid future risk assessment initiatives.

Seasonal distribution of pharmaceuticals in marine water and sediment from a mediterranean coastal lagoon (SE Spain)

The seasonal variations in the occurrence and distribution of pharmaceuticals were evaluated in seawater and sediment of Mar Menor lagoon from spring 2010 to winter 2011. A total of 20 pharmaceuticals in seawater and 14 in sediments were found at concentrations from low ngL−1 up to 168ngL−1 (azithromycin) in seawater and from low ngg−1 up to 50.3ngg−1 (xylazine) in sediments. Azithromycin, xylazine and metoprolol were the most ubiquitous compounds in seawater since they were found in all seawater samples collected. Seven compounds were quantified in both matrices: clarithromycin, erythromycin, hydrochlorothiazide, irbesartan, losartan, salicylic acid and valsartan. Seasonal distribution profiles revealed different sources of pollutants associated to both, El Albujón watercourse (which receives the input of a WWTP) and other non-controlled discharges, into the lagoon. In summer the highest concentrations in seawater for most of the pharmaceuticals were detected close to main touristic nuclei, probably as consequence of sources such as the excretion from bathers and/or other non-controlled discharges, these being significantly higher than in autumn and winter for antibiotics. On the contrary, the mean concentration of lorazepam was significantly higher in colder seasons than in warmer ones. Sulfamethoxazole, erythromycin and especially clarithromycin showed hazard quotients higher than 1 in seawater at some areas of this lagoon indicating a potential risk to aquatic organisms in such specific areas.

A Smart Sensor System for Detecting Hydrocarbon Volatile Organic Compounds in Sea Water

Hydrocarbons are among the most dangerous pollutants for the marine environment. The creation of smart systems to detect hydrocarbon spills in the marine environment is often complex and involves many issues. This paper presents an innovative approach based on a sensor system capable of detecting volatile organic compounds (VOCs) produced by hydrocarbons. The system was composed of an array of photo ionization detectors, lodged in a flow chamber and arranged in radial symmetry, in order to receive the same amount of air flow. The air inlet was placed on the upper face of the chamber, while the air outlet was on the lower face. The sensor characterization at the laboratory bench was performed using different kinds of hydrocarbons, such as gasoline, diesel fuel, kerosene, and crude oil, and their response was acquired using a smart electronic system based on an Arduino™ electronic board. With this approach, it was possible to detect mild‐to‐high concentrations of VOCs with a portable, lightweight, smart system, placed in an autonomous underwater vehicle and in a moored buoy.

The role of humic and fulvic acids in the phototransformation of phenolic compounds in seawater

Humic substances (HS) are known to act as photosensitizers toward the transformation of pollutants in the surface layer of natural waters. This study focused on the role played by HS toward the transformation of xenobiotics in seawater, with the purpose of assessing the prevailing degradation routes. Phenol was chosen as model xenobiotic and its transformation was investigated under simulated sunlight in the presence of terrestrial or marine humic and fulvic acids, in pure water at pH8, artificial seawater (ASW) or natural seawater (NSW). The following parameters were determined: (1) the phenol degradation rate; (2) the variation in HS concentration with irradiation time; (3) the production of transformation products; (4) the influence of iron species on the transformation process.Faster transformation of phenol was observed with humic acids (HA) compared to fulvic acids (SRFA), and transformation induced by both HA and SRFA was faster in ASW than that in pure water. These observations can be explained by assuming an interplay between different competing and sometimes opposite processes, including the competition between chloride, bromide and dissolved oxygen for reaction with HS triplet states.The analysis of intermediates formed in the different matrices under study showed the formation of several hydroxylated (hydroquinone, 1,4-benzoquinone, resorcinol) and condensed compounds (2,2′-bisphenol, 4,4′-bisphenol, 4-phenoxyphenol). Although 1,4-benzoquinone was the main transformation product, formation of condensed molecules was significant with both HA and SRFA. Experiments on natural seawater spiked with HS confirmed the favored formation of condensed products, suggesting a key role of humic matter in dimerization reactions occurring in saline water.

Partitioning of alcohol ethoxylates and polyethylene glycols in the marine environment: Field samplings vs laboratory experiments

Nowadays, alcohol ethoxylates (AEOs) constitute the most important group of non-ionic surfactants, used in a wide range of applications such as household cleaners and detergents. Significant amounts of these compounds and their degradation products (polyethylene glycols, PEGs, which are also used for many other applications) reach aquatic environments, and are eliminated from the water column by degradation and sorption processes. This work deals with the environmental distribution of AEOs and PEGs in the Long Island Sound Estuary, a setting impacted by sewage discharges from New York City (NYC). The distribution of target compounds in seawater was influenced by tides, consistent with salinity differences, and concentrations in suspended solid samples ranged from 1.5 to 20.5μg/g. The more hydrophobic AEOs were mostly attached to the particulate matter whereas the more polar PEGs were predominant in the dissolved form. Later, the sorption of these chemicals was characterized in the laboratory. Experimental and environmental sorption coefficients for AEOs and PEGs showed average values from 3607 to 164,994L/kg and from 74 to 32,862L/kg, respectively. The sorption data were fitted to a Freundlich isotherm model with parameters n and log KF between 0.8–1.2 and 1.46–4.39L/kg, respectively. AEO and PEG sorptions on marine sediment were also found to be mostly not affected by changes in salinity.

Antifouling strategies and corrosion control in cooling circuits

Biofouling and corrosion phenomena dramatically reduce the functionality of industrial cooling circuits, especially in marine environments. This study underlines the effectiveness of a low level chlorination treatment of seawater to prevent biological fouling and biocorrosion.Reported examples emphasize the reaction of chlorine with bromide, ammonia and organic compounds in seawater and the effectiveness of a treatment performed in such a way to guarantee a residual concentration lower than 3μM at the outlet of the condensers.In a brief review of antifouling strategies, alternatives to chlorination and the monitoring approach able to optimize the treatments are also reported.An integrated, on-line system based on electrochemical probes (Biox system and a linear polarization resistance probe) demonstrated to be sufficient to monitor in real time: corrosion, biofilm growth and chemical treatments based on chlorine or alternative oxidant products (chlorine dioxide, etc.).A careful electrochemical monitoring and the optimized treatments help the plant operators of industrial cooling circuits prevent the decay of the equipment performance, allowing at the same time the control of the halogenated by-products formation.