Seawater Phase Research Articles

Neural network reconstruction for tomography of a gravel-air-seawatermixture

This paper presents the first practical implementation of electricalimpedance tomography for the imaging of a gravel-air-seawater mixture,whereinthe image reconstruction is performed using a neural network. Althoughresearch into the use of neural networks for image reconstruction has beendone, previous work has predominantly made use of simulated capacitance orimpedance readings to train the networks. In contrast, this paper adopts a newpractical approach whereby the networks are trained and tested using real datafrom an existing impedance tomography system. The practical aspects ofgenerating this database are discussed and the network training details aregiven. Results indicate that the trained networks are able to discriminateamong the seawater, gravel and air phases and reconstruct images of bubbleconfigurations not included in the training database. In terms of the intendedapplication, accurate predictions of volume fraction are required.Consequently, this paper examines an alternative solution to this problem,wherebythe networks are trained to predict the volume fractions directly rather thanfirst performing an image reconstruction as is standard. Results indicate thatthese volume fraction predictors outperform the image reconstruction networksin terms of the accuracies of the volume fraction predictions for each of thethree phases.

Trace metals, arsenic and lead isotopes in dissolved and particulate phases of North Australian coastal and estuarine seawater

Total dissolved ( m) metal concentrations (Cd, Co, Cu, Fe, Pb, Ni and Zn), analysed by an ammonium pyrrolidine dithiocarbamate (APDC) solvent extraction/Hg exchange back-extraction method, arsenic concentrations and lead isotope ratios (Pb-208/Pb-206 and Pb-207/Pb-206), were determined on seawater samples from nine tropical north Australian estuarine and coastal areas. The low metal concentrations (e.g. av. Zn 38-154 ng/1 and Pb 3.9-13.3 ng/1) and low molar Zn/Cd ratios (av. 17-65) were at near-pristine levels. There were only few strong element/salinity and inter-element correlations, which is attributed mainly to the restricted salinity range sampled (91% of samples had salinity > 20). Metal (APDC-extractable) and arsenic concentrations and lead isotope ratios were also determined on unfiltered samples (dissolved plus particulate phases). The APDC-extractable metals method provided a measure of labile metals in the particulate phase. There were strong positive correlations between suspended particulate matter (SPM) and unfiltered metal concentrations, except for Cd. The slopes of the trendlines approximated the average labile metal concentration in the SPM. In the shallow Bynoe and Norman Rivers' estuaries, which have extensive depositional banks of fine-grained sediments, SPM consisted mainly of re-suspended local bottom sediments. In these estuaries, the ratio of labile metal concentration in SPM to acid extracted total metal concentration in the m grain size fraction of bottom sediments was in the order Pb > Cu > Zn approximate to Ni. A more direct measure of metal lability was obtained from the South Alligator and Adelaide Rivers' estuaries by comparing APDC-extractable concentrations in SPM with total concentrations derived by analysis of acid-digested SPM retained on 0.45 mum membrane filters. The order of lability in these estuaries was Pb > Zn > Cu approximate to Ni. Distribution coefficients (K-D) for metals between the particulate (> 0.45 mum) and dissolved ( m) phases showed a general order of log K-D values for all sites of Fe > Pb > Zn > Ni approximate to Cd approximate to Cu. This is in contrast to the order Cu > Cd > Zn > Ni commonly reported in polluted estuaries and rivers. The north Australian data showed strong log K-D versus SPM correlations for Fe and Cu. The Pb isotopic composition of both filtered and unfiltered samples was similar to previously recorded values for oceanic seawater (Pb-208/Pb-206 = 2.02-2.10). In contrast, the Pb-208/Pb-206 ratios of Pb-Zn ores in the region range from 2.21 to 2.25 allowing the use of Pb isotope data as sensitive indicator of any future impacts from mining developments. Variations in the Pb isotope ratios of unfiltered samples (dominated by Pb in SPM) between some estuaries were found to reflect different compositions of geological units in their catchments. (C) 2001 Elsevier Science BY. All rights reserved.

Endocrine control of Na+,K+-ATPase and chloride cell development in brown trout (Salmo trutta): interaction of insulin-like growth factor-I with prolactin and growth hormone.

A 2-factorial (3x3) injection experiment was used to investigate the effect and interaction between different hormones on the initial phase of seawater (SW) acclimation in brown trout (Salmo trutta). Each fish was given 4 injections on alternate days in freshwater (FW). Factor 1 was either saline, 2 micrograms ovine prolactin (oPRL)/g, or 2 micrograms ovine growth hormone (oGH)/g. Factor 2 was either 0, 0. 01, or 0.1 mirograms recombinant human insulin-like growth factor-I (rhIGF-I)/g. In each of the 9 treatment groups, half of the fish were subjected to a 48-h SW-challenge test, and the remaining fish were sham-transferred to FW one day after the last injection. Hypo-osmoregulatory performance was increased by GH and impaired by PRL treatment as judged by changes in plasma osmolality, [Na+], [Cl-], total [Mg] and muscle water content (MWC) after SW transfer. IGF-I reduced plasma osmolality after transfer to SW but had no effect on plasma total [Mg] or MWC. The effects of the two factors on plasma osmolality, [Na+], [Cl-], and MWC were additive. In sham-transferred fish, GH and IGF-I, alone and in combination, stimulated Na+,K+-ATPase alpha-subunit mRNA (alpha-mRNA) content in the gill. This was paralleled by an overall increase in gill Na+, K+-ATPase activity in fish treated with 0.01 micrograms IGF-I/g. Simultaneous administration of PRL completely inhibited the increase in gill alpha-mRNA observed in the IGF-I-injected groups. Combination of GH and IGF-I did not further affect the alpha-mRNA level relative to the single hormone-injected groups. There was an overall decrease in Na+,K+-ATPase activity in pyloric caeca and middle intestine by the low dose and both doses of IGF-I respectively. No effect was observed in the posterior intestine. PRL and GH treatments did not affect enzyme activity in any intestinal segment. Both doses of IGF-I increased Na+,K+-ATPase-immunoreactive (NKIR) cell density in gill primary filaments. PRL and GH had no effect on primary filament NKIR cell density. GH and both doses of IGF-I reduced secondary lamellar NKIR cell density, whereas PRL had no effect. The main conclusion is that IGF-I and GH induce an overall redistribution of NKIR cells away from the secondary lamella onto the primary filament of FWacclimated trout. This is associated with an overall increased alpha-mRNA level in the gill, which may reflect an increased expression within individual NKIR cells in the primary filament. PRL completely abolished the IGF-I stimulation of alpha-mRNA levels, suggesting a desensitisation of the gill tissue to IGF-I, which may explain the overall anti-SW adaptive effect of PRL.

The effect of dietary lipid on polyunsaturated fatty acid metabolism in Atlantic salmon (Salmo salar) undergoing parr-smolt transformation.

The aim of this study was to measure the changes in lipid metabolism which occur during smoltification and seawater transfer in Atlantic salmon (Salmo salar). Duplicate groups of Atlantic salmon parr were fed diets containing either fish oil (FO) or a blend of linseed and rapeseed oils, vegetable oil (VO), from October (week 0) to seawater transfer in May (week 26). From May to August (weeks 26-43), all fish were fed a fish oil-containing diet. Fatty acyl desaturation and elongation activity were followed in isolated hepatocytes incubated with radioactive 18:3n-3 and 18:2n-6. Metabolism of 18:3n-3 was consistently around 5-fold greater than metabolism of 18:2n-6, and total metabolism of both substrate polyunsaturated fatty acids (PUFA) was increased in fish fed both VO and FO up to seawater transfer after which desaturation activities were reduced. Desaturation activities with both 18:3n-3 and 18:2n-6 were significantly greater in fish fed VO, compared to fish fed FO, at 22 and 26 wk. Arachidonic acid (20:4n-6; AA) in liver polar lipids (PL) of fish fed VO increased consistently from weeks 0-22 but varied after seawater transfer. In fish fed FO, AA in liver PL remained constant up to week 17 before increasing at seawater transfer and leveling off thereafter. Eicosapentaenoic acid (20:5n-3; EPA) in liver PL of fish fed VO decreased significantly from week 0-22 before rising at seawater transfer and increasing rapidly posttransfer. EPA in liver PL of fish fed FO showed a similar trend except EPA was always greater in the freshwater phase compared to fish fed VO. Docosahexaenoic acid (DHA) levels in liver PL of fish fed VO remained constant in the seawater phase before increasing following seawater transfer. In fish fed FO, DHA in liver PL increased from weeks 0-17 reducing and leveling off postseawater transfer. The levels of PGF(2 alpha) and PGF(3 alpha) were measured in isolated gill cells stimulated with calcium ionophore A23187. PGF(2 alpha) production in fish fed VO increased significantly between 0-7 wk before decreasing toward seawater transfer. After transfer, PGF(2 alpha), production increased to a peak at 35 wk. PGF(2 alpha) production in fish fed FO was not significantly altered during the trial period. The changes in PGF(3 alpha) production were broadly similar to those occurring with PGF(2 alpha), but the latter was always in excess of the former (2- to 4-fold). Plasma chloride concentrations in fish subjected to seawater challenge at 20 wk were significantly lower in fish fed VO compared to those fed FO. This study has provided new information on the changes in lipid metabolism which accompany parr-smolt transformation and suggests that diets which have a fatty acid composition more similar to that in aquatic invertebrates may be beneficial in effecting successful seawater adaptation.

Determination of uranium and thorium in solar salts by neutron activation analysis

Uranium and thorium contents of solar salts were measured by neutron activation analysis. In advance of neutron irradiation, U and Th were concentrated and separated from some interfering elements by neutralization in which they were precipitated with aluminium hydroxide from solutions obtained by dissolving the salts in water or dilute nitric acid solution. The uranium and thorium concentrations determined were from several hundred ppt to 10 ppb. It was strongly indicated that uranium tends to remain in the solution (brine from seawater) phase in the process of solar salt production while thorium tends to transfer to the solid (solar salt) phase.

Occurrence of organotin compounds in water and biota from alexandria harbours

Tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT) have been determined in the dissolved and particulate phases of seawater as well as biota collected in the western and eastern harbours. The highest levels were found in seawater of dry dock of the western harbour. Triphenyl- (TPhT) and diphenyltin (DPhT) were also idenified. Concentration ratios between TBT/ DBT and TPhT/ DPhT in all environmental samples were calculated.

The impact of marginal ice zone processes on the distribution of 21OPb, 21OPo and 234Th and implications for new production in the Bellingshausen Sea, Antarctica

The vertical distributions of 21OPb, 210Po and 234Th in both dissolved and particulate phases of seawater were measured at five stations along the 85°W meridian in the Bellingshausen Sea, Antarctica. Sea-ice conditions during the expedition ranged from fully ice-covered (fast ice) to open water away from the marginal ice zone. Concurrent primary productivity and algal chlorophyll measurements revealed a band of high productivity at approximately 67°30′S, which remained in a rather static location during ice melt-back. Along the transect a progressive increase in removal (“scavenging”) and sinking of 210Pb, 210Po and 234Th occurred towards the north (open water conditions). Application of a simple, irreversible scavenging model, and particulate organic carbon and organic nitrogen to radionuclide ratios measured on suspended particulate matter, allows the calculation of export production for this region. Under fast ice conditions some removal of phytodetritus from the euphotic zone was observed (1–2 mgC m −2 day −1), representing a low proportion of the primary production ( f-ratio of 0.02). Near the Antarctic continental margin upwelling of regenerated dissolved 210Po was found. At the open water site near the algal band, new production had risen to 27–252 mgC m −2 day −1, but a greater proportion of the original primary production was removed by sinking detritus ( f-ratio of 0.03–0.33). Comparison of 210Po and 234Th as tracers of of export production indicates considerable differences, with 210Po yielding rather lower rates of export flux compared to 234Th Radionuclide estimates of new production are significantly greater than those obtained by traditional sediment trap methods. This may be due to the dynamic nature (short duration and spatial variability) of algal growth in the Southern Ocean.

Betaine/amino acid additive enhances the seawater performance of rainbow trout ( Oncorhynchus mykiss) fed standard fish-meal-based diets

The effect of betaine ( + amino acid) supplementation on the seawater adaptation of rainbow trout was studied with fish weighing about 200 g at seawater transfer. The fish were fed various levels (OS1.5%) of FinnStim, a commercial product with betaine as the main component, for a 2-month period before seawater transfer and for 5 months in seawater. FinnStim was added to a standard (NSM =Norsea meal) fish-meal-based diet and two kinds of control treatments were used: NSM diet without FinnStim and a similar LT (low temperature) fish meal diet without FinnStim. Growth and mortality were followed during the course of the study and the ionic and osmotic balance of fish estimated prior to seawater transfer at 1 day and 1 week after transfer. FinnStim had a dose-dependent effect on growth and mortality of the fish in seawater. The highest response was obtained with 1% FinnStim in the diet, with a 60% reduction in mortality and 12% increase in specific growth rate during the seawater phase. While the main plasma electrolytes showed no clear response to FinnStim treatment, the intramuscular potassium load in seawater was less pronounced in FinnStim-fed fish. The data, together with those obtained with salmon, clearly indicate that intracellular accumulation of betaine decreases the osmotic inhibition of metabolism at seawater transfer; l-1.5% inclusion of betaine in the diet seems to be optimal for this response.

Effects of a dietary betaine/amino acid additive on growth and seawater adaptation in yearling chinook salmon

The effect of FinnStim, a betaine/amino acid mixture, on growth and seawater adaptation was studied in yearling chinook salmon Oncorhynchus tshawytscha. The fish were marked with PIT tags and divided into two groups. One group was fed a diet with 1% FinnStim added and the other was fed a control diet with 1% α-cellulose. The diets were fed for 6 weeks in fresh water at a level of 1% body weight per day and for 8 weeks in seawater netpens at 3% body weight per day. Seawater challenge tests were conducted three times during the freshwater phase of the experiment. Growth and mortality in fresh water did not differ significantly between treatments. Seawater challenge tests at days 5, 47 and 70 of freshwater rearing revealed no significant difference in plasma sodium concentration between groups. During the seawater phase of the experiment, the group receiving FinnStim had a significantly higher growth rate and a significantly lower concentration of plasma sodium at the end of the study. The improved growth performance in the group receiving FinnStim was due to a reduction in the number of salmon growing poorly.

Speciation of cadmium in seawater ? a direct voltammetric approach

The present report deals with differential pulse anodic stripping voltammetry (DPASV) applied for the analysis of cadmium in open ocean seawater. Evaluation of different Cd species can generate information about distribution and speciation of Cd in the open ocean. Distribution of Cd was investigated in surface waters of the Atlantic Ocean over a wide geographical range as well as in the water column. Surface water sampling on board the research vessel Polarstern was performed from the bow boom of the ship as well as with a snorkel system which allowed continuous sample-taking. Two different Cd species could be differentiated in the voltammograms. UV-irradiation experiments allowed the identification of an inorganic and organic Cd form, the latter caused by the association between Cd and organic matter as e.g. humic substances (HS). Atlantic ocean surface seawater normally contains between 2 and 4 ng organically complexed Cd/kg and no detectable inorganic Cd. Some areas however showed readings of up to 14 ng inorganic Cd/kg in addition. Water column samples exhibited an enrichment of inorganic Cd by depth. Occurrence of inorganic Cd at the surface could be related to specific oceanographical conditions. Together with analytical results of trace metal contents in the particulate phases of surface seawater, new aspects could be established about the biogeochemical cycling of Cd in the sea.

Partitioning of polychlorinated biphenyl congeners in the seawater of New Bedford Harbor, Massachusetts

The partitioning of polychlorinated biphenyls (PCBs) between particulate and dissolved phases of seawater was examined along a concentration gradient in New Bedford Harbor, MA. Regression analysis was used to examine the relationship between the log of the partition coefficients (K[sub p]) and the log of the octanol/water partition coefficients (K[sub ow]) for six PCB cogeners at four stations. A seasonal trend (i.e., summer-winter) in partitioning was observed. Log (K[sub p]) was inversely correlated with temperature and to a lesser extent with total suspended solids (TSS) at each station. Multiple regression analysis indicated that approximately 70 percent of the variability in log K[sub p] along the PCB concentration gradient was accounted for by temperature, log K(sub ow), and TSS. Temperature and log K[sub ow] were equally important in defining changes in log K[sub p], with TSS contributing the least predictive ability.

Chemometrical interpretation of analytical data for vertical distribution of some chemical components in sea water

Analytical data for vertical distribution (depth profile) of components in sea water are interpreted by the use of multivariate statistical methods (principal components analysis, correspondence factor analysis and cluster analysis). The various chemical components (NH3, P, Zn, Mn, Cu, Fe, O2, pH, salinity and alkalinity) and some physical characteristics (Eh, T, suspended matter) or the depths of sampling (from 0 to 200 m) are classified as objects of similarity. Two principal components are identified as possible really existing natural factors determining the vertical distribution of the components in the sea water phase.

Le nannoplancton calcaire et la formation des alternances calcaires-marnes dans le lias des bassins de Marches-Ombrie (Italie)

In the classical sections of Sentino-Valdorbia, Bosso and the Marne di Monte Serrone type-section the rhythmic, limestone/marl sedimentation of the following formations were studied: the Corniola (Late Sinemurian to Earliest Toarcian) and the Marne di Monte Serrone (Early Toarcian). The geological framework is drawn from the numerous and significant published papers which give a good stratigraphical scheme and a precise paleogeographic setting. The limestones have been studied in thin sections (texture, occurrence and abundance of schizospheres, other fauna, etc.) and with SEM (structure, occurrence, abundance and diagenetic state of schizospheres; coccoliths). Marly interbeds have been studied in light microscopy on smear slides of raw sediment to find out coccoliths and schizospheres and with SEM, both on washed and centrifuged sediments (for a better definition of the nannofloras) and on freshly broken surfaces. The conclusions are based upon 69 SEM pictures of limestones and 94 SEM pictures of marls from the Corniola Formation; on 169 SEM pictures of limestones and 303 SEM pictures of marls from the Marne di Monte Serrone Formation. The observations show the importance of the nannofloral contrast between the Limestone beds with schizospheres and the marly interbeds with coccoliths. The contrast is thought to portray rhe original difference between the components which generated the two different types of sediments. The lithogenetic role of the nannoplankton was strongly differentiated and was linked to an alternation of clay-poor, sea-warer phases when stable, calcareous nannoplankton (schizospheres) dominated and did not evolve and of clay-richer, sea-water phases when coccolithophorids expanded and evolved.

Effects of ambient ammonia on ammonia-N and protein concentrations in hemolymph and ammonia-N excretion of Penaeus chinensis

Individual Penaeus chinensis adults (26.91 + 4.66 g) were subjected to 0.03, 5.10, 10.11 and 20.04 mg I-' ammonia-N (un-ionized plus ionized ammonia as nitrogen) in 30 ppt seawater and 25 C. Changes in ammonia-N excretion, hemolymph ammonia-N and hemolymph protein were monitored for 1 to 24 h. Net ammonia-N uptake occurred when shrimp were exposed to 10.11 and 20.04 mg I ' ammonia-N after 4 h. Relationships among ammonia-N excretion rate, hemolymph ammonia-N, hemolymph protein, concentration of ambient ammonia-N and exposure time were determined. An increase of ammonia-N and a decrease of protein in the hemolymph of P chinensis following a 4 h exposure to ambient ammonia-N as high as 10 mg 1-' may cause catabolism of protein and amino ac~ds to balance the osmoregulation, as well as dysfunction of Na+/NH,+ exchanges. The fleshy prawn Penaeus chinensis Osbeck is a typical penaeid which matures and spawns in seawater, spends postlarval and juvenile phases in brackish water, then returns to the sea as a preadult. It is also an important penaeid currently being cultured in China, Taiwan and Korea (Chen 1990). This species can be reared at salinities ranging from 20 to 32 ppt which was considered the optimal level by Liu (1983). Ammonia, the end-product of protein catabolism, accounts for more than half of the nitrogenous waste of decapod crustaceans and is continually released. Ammonia is excreted mainly through the gill epithelium (Regnault 1987). Protein and amino acids can serve as a significant source of metabolic energy for crustaceans (Claybrook 1983). A decrease in the ambient osmotic concentration increased catabolism of amino acids, causing an increase in ammonia-N excretion (Lange 1972). Ammonia has been reported to affect osmoregulation of crustaceans (Young-Lai et al. 1991). However, there is no information concerning its effect on protein and amino acid level in the hemolymph. This study was designed to monitor hemolymph ammonia-N, hemolymph protein and ammonia-N excretion of Penaeus chinensis adults exposed to different concentrations of ammonia-N. Materials and methods. Penaeus chinensis adults obtained from Tainan Branch, Taiwan Fisheries Research Institute, Keelung, were acclimated in a holding tank for 1 wk and fed commercial shrimp feed (39 %crude protein) designed for P monodon (Tairoun Products Co., Taipei, Taiwan) once a day. Shrimp were not fed for 2 d prior to the experiment. Starved shrimp were randomly removed from the holding tank and individually transferred to a 20 1 circular plastic tank containing 10 1 of each test solution. Individual tanks were aerated through an air blower attached to an aeration stone. Only shrimp in the intermolt stage (Wassenberg & Hill 1984) were selected for the study. There were 20 treatments, 4 test combined with 5 exposure times: 1, 4, 8, 16 and 24 h. For each treatment there were 5 replicates. The total number of shrimp used was 105, 5 for each treatment plus 5 for an initial control solution. Shrimp used ranged from 21.25 to 30.52 g with an average weight of 26.91 -t 4.66 g ( R k SD) and no significant difference in weight was found among treatments. In addition, 10 tanks containing aerated test solution only (duplicates for each test solution) were used as blanks. Ammonia test consisting of concentrations of 0.03 (control), 5.10, 10.11 and 20.04 mg 1-' ammonia-N were prepared according to the procedure reported previously (Chen & Nan 1992). The experiment started at 09:OO h and lasted for 1, 4 , 8, 16 and 24 h under a photopenod of 12 h light: 12 h dark with a light intensity of 160 to 250 lux during the day. The concentration of ammonia-N was determined by the phenolhypochlorite method (Solorzano 1969) at the beginning and end of the experiment. Ammonia-N excretion was cal0 Inter-Research 1993 204 Mar. Ecol. Prog. Ser. 98: 203-208, 1993 Table 1. Penaeus chinensis. Mean (f SE) concentration of ammonia-N over time for blank solutions (B) and test contaming shrimp (T) Initial ammonia-N conc. (mg 1 l ) Ammonia-N concentration (mg 1.') after:

Polychlorinated biphenyls and organochlorine pesticides in marine sediments and seawater along the coast of Alicante, Spain

In this paper we present the results obtained in a sampling programme carried out from 1989–1990, whose aim was to study the presence of organochlorine compounds in marine sediments and seawater along the coast of Alicante, Spain. There have been identified DDTs, HCHs, HCB, cyclodienic pesticides and derivatives and PCBs (Aroclor type commercial mixtures and selected PCB congeners). The analytical method consists of 3 phases, i.e. extraction, cleanup and analysis through capillary gas chromatography with electron capture detection. The amount of material used for extraction was 1 kg of sediment samples and 50 l of seawater samples. The levels of organochlorines in sediments are low. Concentration ranges were as follows: PCB total, 0.05–9.69 ng g −1, sum of DDTs, 0.01–0.3 ng g −1, Hexachlorobenzene (HCB), 0.01–0.12 ng g −1, and smaller values for other compounds. In the dissolved phase of seawater there were identified HCHs in concentrations ranging from 1.3–2 ng l −1.

Occurrence and fate of tributyl‐ and triphenyltin compounds in western mediterranean coastal enclosures

AbstractTributyltin (TBT) and its degradation products, mono‐ (MBT) and dibutyltin (DBT) have been determined in the dissolved and particulate phases of seawater, sediments, and biota collected in some representative open and enclosed coastal areas of the western Mediterranean Sea. The highest levels were found in sediments and seawater of dry docks and marinas, closely related with boating activity and clearly decreasing according to the distance from the point sources. Triphenyl‐ (TPhT) and diphenyltin (DPhT) were also identified for the first time in seawater and sediments collected in marinas, exhibiting concentrations similar to TBT. Concentration ratios between TBT/DBT and TPhT/DPhT in each environmental compartment as well as the field partition coefficients (Kd, K′d, and Kb) of the different tin species point out the complexity of organotin speciation, because accumulation and degradation processes occur at different rates, depending on the environmental compartment.

Behaviour of selected polycyclic aromatic hydrocarbons associated with stabilized oil and coal ash artificial reef

An experimental artificial reef consisting of oil and coal fly ash stabilized with cement and lime has been placed in the Atlantic Ocean off the east central coast of Florida. The oil and fly ash were found to contain levels of polycyclic aromatic hydrocarbons (PAH) similar to a moderately contaminated sediment. Detectable concentrations of individual PAH ranged from highs in the oil ash of 1200 and 270 ng g −1 to lows of 250 and 49 ng g −1 in stabilized bricks for fluoranthane and naphthalene, respectively. The stabilization process used in the construction of the reef bricks reduced the extractability of PAH from reef bricks by hot organic solvents. Because of the toxicity of some PAH, there is concern for leaching of the PAH by seawater from the waste ash used for construction of the reef. Leaching studies of the reef materials with seawater, however, indicated PAH are retained within the reef materials and that seawater is not an effective medium for removing PAH from reef bricks or the ash. Furthermore, the reef materials were found to adsorb PAH from the seawater phase. These results indicate that the stabilization of oil ash is an efficient tool for isolating PAH from environmental circulation.

Partitioning of urban wastewater organic microcontaminants among coastal compartments

A variety of organic compounds including alkanes (UCM), polycyclic aromatic hydrocarbons (PAHs), hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), 4,4′-DDE, long-chain alkylbenzenes (LABs), long-chain alkylnitriles (LANs), trialkylamines (TAMs), alkylphosphates (APs), and organotin derivatives (tributyl- and triphenyltin) have been determined in biotic and abiotic compartments close to an urban wastewater disposal site. The field apparent partition coefficients between particulate and dissolved seawater phases (K'd) and biota and water (Kb) of these organic contaminants were calculated in order to assess their fate in the marine environment.

The rate of oxidation of ferrous iron in seawater and the partition of elements between iron oxides and seawater

At the Minamichita Beach Land (Mihama-cho, Aichi, Japan), seawater is pumped up from underground and is supplied to aquaria. The underground seawater containsca. 2 ppm of Fe (II), 0.1 ppm of Mn (II) and a little dissolved oxygen. Iron oxide is formed in the seawater when aerated. The oxidation rate of Fe (II) was measured to be 1.4×1014 mol−3 l 3 min−1, which is comparable to the lowest values in the literature. The slow rate of Fe (II) oxidation obtained here can be attributed to the presence of organically bound iron in the seawater. The distribution coefficient of cations between seawater and iron oxide phase was in the order of Cu>Ni>Co>Cd>Mn, which is consistent with that predicted from their hydrolysis constants. The adsorption affinity sequence of oxyanions was phosphate >vanadate> molybdate. The difference in phosphate from the prediction of the adsorption theory was attributed to the formation of ferriphosphate on the oxide surface. On the basis of these data, the limitation and usefulness in the application of the distribution coefficients to marine environments were discussed.

The control of trace metal concentrations in coastal seawater through partition onto suspended particulate matter

The distribution of total metal concentration between dissolved and particulate phases in coastal seawater has been examined as a function of suspended particulate matter (SPM) loading. Partition between dissolved and particulate phases, as defined by a distribution coefficient, is demonstrated to be an important control on the concentration in each phase. The possible impact of anthropogenic inputs on trends in coastal water concentrations are contrasted for waters with a high (Netherlands), and a low (U.K.), SPM loading. For a given increase in input trends will be more readily detected in areas with a slow SPM loading. It is concluded that trends in coastal seawater concentrations will only become apparent after river inputs have dramatically increased. Monitoring coastal water concentrations of dissolved and particulate phase trace metals is not therefore likely to be a sufficiently sensitive technique to detect trends.