Microlayer Samples Research Articles

Concentration of Tributyltin in the Surface Microlayer of Natural Waters

Abstract High concentrations of the very toxic antifouling agent tributyltin have been found in 24 surface microlayer samples in a survey of 74 locations in Ontario, Quebec, and New York State. In 6 of these 24 locations the concentration of tributyltin in the surface microlayer exceeded the 24-hr LC-50 value for adult rainbow trout. The most heavily contaminated area was the mouth of the Moira River at Belleville, Ontario, where the concentration of tributyltin in the surface microlayer was 42 times the 24-hr LC-50 value for trout. The concentration of tributyltin in the surface microlayer was occasionally so much greater than that in subsurface water that the microlayer contained a significant amount of tributyltin relative to that in the whole depth of the subsurface water. Similar findings were observed for the less toxic degradation products of tributyltin - dibutyltin, monobutyltin and inorganic tin.

Contaminant concentrations and toxicity of sea-surface microlayer near Los Angeles, California

Sea-surface microlayer samples were collected from six nearshore areas receiving different amounts of anthropogenic inputs. The samples were analyzed for selected trace metals, chlorinated hydrocarbons, and polycyclic aromatic hydrocarbons. The relative toxicities of the samples were determined with fish embryo bioassays. Contaminant concentrations generally increased from offshore to the inshore stations. Contaminant concentrations were several orders of magnitude higher in microlayer samples from the highly industrialized Los Angeles and Long Beach harbors compared to samples from a site 15km offshore. Microlayer samples from the inshore stations were significantly more toxic, and induced significantly more developmental abnormalities and chromosome aberrations, than samples from the offshore stations.

The sea-surface microlayer of puget sound: Part I. Toxic effects on fish eggs and larvae

The sea surface is an important habitat for the developmental stages (eggs and larvae) of many fish and invertebrates; it is also a concentration point for anthropogenic contaminants entering the sea. Studies were conducted to determine the extent to which the sea surface of Puget Sound was toxic to the early life history stages of fish. Three urban bays with suspected contamination, a rural reference bay, and a Central Sound site were compared. Surface-dwelling eggs and organisms (zooneuston) were collected with a surface-skimming neuston net and their densities enumerated. Sand sole ( Psettichthys melanostictus) embryos were exposed in the field and laboratory to the sea-surface microlayer. To develop a useful year-round approach to monitoring sea-surface toxicity, larval development of anchovies, kelp bass, and sea urchins was also evaluated as an indication of sea-surface microlayer toxicity. During the spawning season (February and March), urban boys in Puget Sound had lower concentrations of sand sole eggs and neustonic organisms on the sea surface than did the rural bayor Central Sound reference sites. Compared to the reference sites, laboratory exposure to surface microlayer samples collected from urban bay sites generally resulted in more chromsomal aberrations in developing sole embryos, reduced hatching success of sole larvae, and reduced growth in trout cell cultures. In situ hatching success of sole eggs was reduced by half or more in urban bays compared to reference sites. Toxicity was associated with visible surface slicks and, in urban bays, increased with increasing surface pressure (dynes cm −1). Results to be reported separately (Part II) indicate that toxicity is strongly correlated with the presence of high concentrations of polycyclic aromatic hydrocarbons and metals in the sea-surface microlayer. The toxicity of SMIC samples was similar when evaluated by sole, anchovy, kelp bass, or sea urchin tests. A sea-surface monitoring program could use sea urchin embryos to evaluate site-specific sea-surface toxicity throughout the year.

Dissolved/dispersed hydrocarbons, tarballs and the surface microlayer: Experiences from an IOC/UNEP Workshop in Bermuda, December, 1984

An intercomparison exercise was conducted at the Bermuda Biological Station for Research, Inc, Bermuda on 1–15 December 1984. It primarily involved the testing of the IOC Manual for monitoring oil and dissolved/dispersed petroleum hydrocarbons (DDPH) in marine waters and on beaches (IOC, Manuals and Guides, No. 13). An additional exercise sought to intercompare methodologies for the collection of sea surface microlayer samples. DDPH measurements in the inshore waters of Bermuda resulted in a mean concentration of 0.057 μg l −1 of ( n = 30) chrysene equivalents with a 60% relative standard deviation (RSD). Open ocean samples yielded a mean concentration of 0.011 μg l −1 ( n = 44) with a 65% RSD. These concentrations are extremely low and the results indicate that the method described in the Manual is sufficiently sensitive for the detection of ‘hot spots’ The collection of beach tar using the method outlined in the Manual indicated that the data, when expresed as per metre of linear beach length, are an extremely good measure of oil contamination. The mean of 42 collections was 23.1 ± 14.4 g m −1 in the first sampling period and the mean of 39 transects was 40.6 ± 17.7 g m −1 on the second sampling period. Although 14 individuals took part in the sampling the results of individuals were consistent enough to demonstrate that beach tar collections are indeed valuable tools for monitoring contamination by petroleum in the marine environment. The operational manual for the sampling of the sea surface microlayer (IOC Manuals and Guides, No. 15), was also tested. The results indicated that this method collects reproduceable volumes of elevated concentrations of materials from the sea surface suitable at least for qualitative analyses. However, the spatial distribution and stability of surface films may render quantitative analyses less meaningful.

Dissolved and particulate amino acids and carbohydrates in the sea surface microlayer

Eleven pairs of sea-surface microlayer (⩽250 μm) and subsurface water (5–15 cm depth) samples were collected near the coast of Baja California. Particulate matter was removed by filtration through polycarbonate membrane filters (8, 1, 0.2, 0.1, and 0.05 μm pore sizes) and the filtrates analyzed for hydrolyzable amino acids and total carbohydrates. Dissolved free amino acids were measured in some samples on board ship. Hydrolyzable amino acids, free amino acids, and total carbohydrates were more concentrated in nearly all microlayer samples than in subsurface water samples taken at the same location. For hydrolyzable amino acids and total carbohydrates, the enrichment was observed for both particulate and dissolved material. Averaging both microlayer and subsurface water samples, about 20% of the dissolved organic carbon and about 60% of particulate organic carbon was identified as carbohydrate or amino acid carbon. Particulate hydrolyzable amino acids were mainly in the 1–8 and 0.2–1 μm size ranges, but particulate total carbohydrates did not usually have pronounced maxima in particle-size distributions. Relative to their proportions in subsurface-water dissolved organic matter, hydrolyzable amino acids were increased over total carbohydrates in the microlayer and in particulate material. Nonpolar hydrolyzable amino acids also had higher concentrations relative to other amino acids in microlayer and particulate organic matter. Differences in microlayer and subsurface water compositions are probably related both to differences in the surface activity of polymers containing amino acids and carbohydrates, and to interactions between surface-active molecules and particles.

Determination of surfactant activity and anionic detergents in seawater and sea surface microlayer in the Mediterranean

The study of the physico-chemical properties and the determination of different classes of organic substances in the sea are of substantial interest and importance for understanding biogeochemical processes in the sea. The preferable method should be sensitive enough for direct measurement without pretreatment procedures in order to avoid changes in the composition of organic substances initially present in the sample. Surfactant activity data are presented here as measured by electrochemical methods during 1979, 1980 and 1981 in samples from open waters of the Western Mediterranean, and in a few characteristic coastal areas of the Adriatic Sea with different biological activity and different influence of man's activities. Data on sea surface microlayer samples collected during 1977, 1978 and 1981 at different locations and seasons in the Rijeka Bay, which is an integral part of the Adriatic Sea, are presented and discussed in more detail. It was found that the type and concentration of natural surface active material vary within different Mediterranean regions and along the depth profile of the water column. Petroleum hydrocarbons and detergents were found to be prevalent pollutants responsible for high surfactant activity values. Pollution effects are most pronounced in the sea surface microlayer. Electrochemical methods are proposed for research and monitoring of surface-active substances in the sea.

Particle size distribution of lipids in aerosols off the coast of Peru

Lipid components in aerosols were characterized as a function of particle size from samples collected in spring 1981 off the coast of Peru as part of the Sea‐Air Exchange Program. The investigation was designed to determine (1) the particle size distributions for different terrestrial and marine source marker organic compounds close to their source, (2) the importance of the atmosphere as an input source to the sea for terrestrial compounds, and (3) the significance of recycling of the terrestrial components of these compound classes from seawater back into the atmosphere. The terrestrially derived components of three compound classes (fatty alcohols, wax esters, and n‐alkanes) were found to have similar particle size distributions. They are relatively evenly distributed over the whole particle size range, suggesting (1) little modification of the wide spectrum of plant‐ and soil‐derived particles by short‐range transport offshore and (2) insignificant gas‐particle partitioning for these materials. On the other hand, the terrestrially derived fatty acid salts show a different particle size distribution probably due to their very different physicochemical properties. The atmospheric flux to the sea surface via both wet and dry deposition is not significant in relation to the flux through the euphotic zone of the water column for two lipids of terrestrial origin, octacosanoic acid and 24‐ethylcholest‐5‐en‐3β‐ol. No significant recycling from the sea surface back into the atmosphere was observed for lipid compounds of terrestrial origin. Marine‐derived sterols, fatty alcohols, and fatty acid salts were found in high concentrations in surface microlayer samples. The enrichment of these compound classes is about 2–4 orders of magnitude relative to bulk seawater.

Measurements of various sulphur gases in a coastal marine environment

Measurements of several sulphur gases have been made in coastal seawaters (including microlayers) and marine air off Great Yarmouth, U.K., and in a freshwater lake. The results show dimethyl sulphide to be the dominant sulphur gas in all the waters examined, with lesser amounts of carbonyl sulphide and carbon disulphide. For the marine air and water samples carbonyl sulphide showed no significant seasonal variation in concentration. The seawater was always supersaturated with respect to the carbonyl sulphide concentration in the air; the mean saturation value being 4.6. Likewise the seawater was always supersaturated with dimethyl sulphide, but for this gas the concentrations in the water showed substantial seasonal variation (× 40), with a maximum value of about 500 ng(S) l-1 in late June, approximately contemporaneous with the second plankton bloom in the region. Sea surface microlayers harvested cryogenically showed a mean enrichment of 2.4 relative to subsurface water for carbonyl sulphide. Some part of the observed microlayer enrichment for this gas may be due to freezing-on of atmospheric carbonyl sulphide onto the frozen microlayer sample. In general, microlayer samples did not exhibit a significant enrichment for dimethyl sulphide. However, under conditions of high biological production, enrichments of several-fold were found, but may be attributable, at least in part, to biological production of dimethyl sulphide in the microlayer water in the period between collection and analysis.

Occurrence of Alkyllead Compounds in the Detroit and St. Clair Rivers

Environmental occurrence of alkyllead compounds, both of molecular species, e.g., tetraalkyllead, and ionic species, e.g., dialkyllead and trialkyllead, is believed to be derived mainly from anthropogenic sources such as effluents of alkyllead production plants and from slow degradation of tetraalkyllead in the environment. The present study describes a survey for the occurrence of tetraalkyllead, trialkyllead, dialkyllead, and Pb(II) (R = Me, Et) in water, surface microlayer, fish, and sediments from 29 stations in the St. Clair and Detroit rivers, including the western basin of Lake Erie. Results indicated that triethyllead and diethlylead compounds have been found for the first time in fish and surface microlayer in St. Clair River near Corunna where a production plant is located. About 48% of the surface microlayer samples contained various alkyllead compounds whereas only one water sample taken from the St. Clair River was found to contain alkyllead. Alkyllead compounds were found in several species of fish caught in the St. Clair River, with northern pike containing the highest concentration of alkyllead (0.173 μg/g) followed by white sucker, carp, and walleye. The concentrations of alkyllead in some individual fish reached the p.p.m. level which is considered highly hazardous for consumption although health criteria for alkyllead are not yet available. The ratios of alkyllead to total lead ranged from 0% for yellow perch and brown trout to 56% for carp.

Effect of heavy metals on natural populations of bacteria from surface micro-layers and subsurface water

The effect of the heavy metals copper and cadmium on natural bacterial populations of surface microlayer and subsurface water was investigated. Two parameters, number of colony-forming bacteria and 14C-glucose uptake rate, were evaluated. The 2 natural bacterial populations showed different responses to the heavy metals. Results support the existence of autochthonous bacterioneuston populations in the marine environment. Although a large number of metals are essential for growth, some can be harmful for living cells. This is mainly due to the fact that heavy metals form complexes with protein molecules which render them inactive, for example, inactivation of enzymes. Many heavy metals are detrimental to microorganisms even at the low concentrations present in natural waters (Mills & Colwell 1977). There are also reports on the adaptation of microorganisms to heavy metals (Azam et al. 1977). This phenomenon has important implications for microbial ecology in polluted ecosystems. Accumulations of bacteria in the surface microlayer have been reviewed by many authors (e.g. Sieburth 1979, Norkrans 1980). Enrichment of toxic substances such as heavy metals in surface microlayers has also been described from various aquatic ecosystems (Baker & Zeitlin 1972, Lion & Leckie 1982). Thus, the physiological state of neuston may be considerably affected by toxic substances. The present study attempted to improve understanding of the biological function of neuston in the marine environment, by investigation of the influence of high heavy metal concentrations on natural populations of bacterioneuston. Seawater was obtained on calm days only from the innermost Kiel Fjord (Baltic Sea, Federal Republic of Germany). Surface microlayer samples were collected with a sterile circular screen (0.1256 m2, 16 mesh, wire diameter 0.35 mm, stainless steel). The thickness of the Present address: Dept. of Microbiology, College of Natural Sciences, Seoul National University, Seoul 151, Korea O Inter-ResearchIPrinted in F. R. Germany sampled surface microlayer was about 430 pm. Sampling from a depth of l m was conducted with a sterile 5 1 glass bottle. The 2 water samples were filtered through a stainless steel sieve (mesh size 75 pm) prior to use to remove larger zooplankton and detritus. Experiments to investigate the effects of copper and cadmium on natural bacterial populations were independently undertaken immediately after collection of seawater samples. The influence of Cd and Cu salts was determined on the basis of bacterial survival (number of colony-forming units) and glucose uptake rate. Sterile standard solutions of heavy metals, Cd(N03), . 4H20 and CuCl, 2H20, were individually mixed with 500 m1 of either neuston sample or subsurface sample. Two different Cd concentrations and a control were tested for each sample. The final concentrations in the sample were 1 and 10 ppb(w/v) (10 ppb Cd = 10 pg Cd 1-' = 27.444 pg Cd(N03),.4H20 1-l). Two concentrations were similarly tested for Cu and reflected 10 and 100 ppb(w/v) (100 ppb Cu = 100 pg Cu 1-' = 268.3 pg CuC1,.2H20 I') . These concentrations are 10 and 100 times greater than natural concentrations at 2 m depth in the investigative area (Kremling et al. 1979). The samples were incubated for 24 h at room temperature and continually shaken. Just prior to the addition of heavy metals, the number of colony-forming units and 14C-glucose uptake rate of the bacteria were determined as initial values. Colony-forming units on 3 parallels of ZoBell agar plates with salinity 17 %O were counted after incubation for 14 d. For the determination of glucose uptake rates, 0.2 m1 of D-(U-14C)-glucose solution (= 2.5 pg C) were added to 3 parallel 10 m1 samples from each experimental set and were incubated for l h at room temperature. One of the 3 parallels was set up as a control (fixed with 0.05 m1 formalin at the start of the incubation) in order to determine the amount of radioactive substances adsorbed. After incubation the samples were fixed with formalin, then filtered 204 Mar. Ecol. Prog. Ser. 26: 203-206, 1985

Estimates of the transport of trace metals from the ocean to the atmosphere

The Bubble Interfacial Microlayer Sampler (BIMS) was used in the North Atlantic to determine the enrichment factors, relative to sodium and the ocean (EFsea), for a series of trace metals on bubble‐derived atmospheric sea salt particles. No enrichment was found for K and Mg within the analytical precision of ±10%. Mean EFsea values determined for Al, Co, Cu, Fe, Mn, Pb, V, and Zn ranged from 10 to 20,000. Positive correlations were found between bubble generation depth and the EFsea values for Fe, Pb, Sc, and Zn. Estimates suggest that the ocean is the primary global source of atmospheric K and Mg, that it is potentially a nontrivial (5–20% of the total) source of atmospheric Cu, V, and possibly Zn, and that it is an insignificant source of Al, Co, Fe, Mn, Pb, and Sc. In the remote North Pacific, during certain periods of the year, the ocean may be the primary source for all these elements present on aerosol particles with diameters greater than ∼3 μm.

Electrochemical Characterization of Fluid Vesicles in Natural Waters

Abstract The electrochemical method of polarographic maximum based on the interfacial instability of a positively charged interface dropping mercury electrode/sea-water, allows a direct characterization of single events of coalescence and transformation of aggregates of fluid surfactants into adsorbed monolayers at the interface (relaxation times 10 – 500 ms, aggregation numbers > 109). Highly surface active aggregates, resembling those of unsaturated lipids, were detected in the sea surface microlayer samples and in the mixing layers in the estuaries, although the unsaturated lipids represent only a minor fraction (<10%) of the aquatic organic matter. Products of flocculation of dissolved organic matter during estuarine mixing resemble closely fluid vesicles released by marine microflagellate, such as Dunaliella tertiolecta, that was studied in a greater detail. The analysis of complex electrochemical responses in natural heterodispersion is developed using artificial dispersions of oleate and methyl ole...

Measurements of biomass and activity of neustonic microorganisms

Microlayer samples from a coastal marine area near Marseilles (France) collected in 1979 and 1980 have been analysed for POC, PON, chlorophyll a, ATP, cell counts, carbon fixation and in some cases for heterotrophic activity. Comparison of microlayer data with those of underlying water showed in most cases enrichment of organic matter and microorganisms in the surface microlayer. Carbon fixation values were comparable to those observed at 0·50 m except in the slicks, where phytoneustonic activity was higher than that of the underlying phytoplankton. Though total heterotrophic activity was higher in the surface film, the turnover time was not significantly different in both microlayer and underlying water. Our data show that enrichment is highly dependent on sea conditions; whenever slicks are present, the surface film seems to function like an eutrophic system, including active living material, although detritus is regularly present in large amounts.

Quantitative changes in fungal colony-forming units in the surface microlayers of two freshwater ponds

The surface microlayer of two small ponds in Wisconsin were studied from March 1979 through November 1979 using glass plate and screen microlayer sampling devices. The numbers of fungal colony-forming units (CFU) in the surface microlayer were determined and compared with numbers in subsurface waters; diel fluctuations were correlated with nutrients; and experiments were conducted to estimate the contribution of spores to surface microlayer populations. The data obtained indicates that the highest number of fungal CFU were located in the surface microlayers of the ponds studied. The numbers present, as well as their enrichment in the surface microlayer, underwent both seasonal and diel fluctuations. Most of the fungal CFU in the surface microlayer appeared to be spores arriving from both allochthonous and autochthonous sources. Qualitative investigations would be necessary to determine the relative importance of either source to the total numbers of fungi observed.

Surface geochemistry at Roosevelt Springs Kgra, Utah

As part of a research program conducted on behalf of the Department of Energy, available data on the Roosevelt Springs KGRA were synthesized to determine the spatial arrangement of the rocks, and the patterns of mass and energy flow within them. The resulting model led to a new interpretation of the geothermal system, and provided “ground truth” for evaluating the application of soil geochemistry to exploration for concealed geothermal fields. Preliminary geochemical studies comparing the surface micro-layer to conventional soil sampling methods indicated both practical and chemical advantages for the surface micro-layer technique. The elements arsenic, antimony and cesium in the surface microlayer samples in particular, gave a strong expression of one of the principal faults in the geothermal field. In contrast the analysis of soil samples from only 20 cm below the surface gave little or no expression of the geothermal field. As a consequence, the surface micro-layer was the chosen sampling medium for the second field program, which entailed the collection of a total of some 300 samples on both a regional and detailed pattern covering about 250 km 2. These samples were subsequently analyzed by a variety of methods yielding data on 41 elements and ions. Computer contouring revealed that, on a single-element basis, cesium, antimony and arsenic provided the best expression of the KGRA, and indicated other interesting areas of geothermal leakage. Elements such as beryllium and lithium, which are present in highly anomalous concentrations in the opaline sinter deposited by geothermal leakage, do not have an expression in the overlying soils or the surface micro-layer. Computer manipulation of the multi-element data using R-mode factor analysis provided the optimum method of interpretation of the surface micro-layer data. A single factor in which the principal contributors were arsenic, antimony and cesium provided the best indication of the leakage of geothermal solutions within the KGRA. Anomalies in the Escalante Desert to the west of the geothermal field are associated with the trace of a fault zone, and may, therefore, be an activity. Trend surface analysis of the soil mercury data has indicated a regional high in this element in the Mineral Mountains to the east of the KGRA, which may indicate the position of a dry heat source at depth. These data demonstrate that surface micro-layer sampling on a regional scale can serve as a prospecting tool for geothermal resource areas. However, it is possible that the optimum pathfinder elements may vary with the nature of heat source, the geochemistry of the local rocks and the local surficial environment. It is therefore recommended that a multi-element approach should be adopted, with subsequent computer processing of the data.

Dissolved organic materials in surface microlayers: Temporal and spatial variability and relation to sea state

Microlayer samples were collected to assess the temporal and spatial variability of their dissolved organic materials (DOM). Dissolved organic carbon (DOC) was often enriched in microlayers but concentration differences between microlayers and bulkwaters were generally small. Ranges of DOC enrichments were large in oceanic samples. Enrichments diminished with increasing bulkwater DOC concentrations in coastal waters and were not influenced by wave states from Beaufort 0 to 4. Microlayer depletions of DOC occurred, but the removal processes responsible for them are unknown. UV‐absorbing phenolic fractions of microlayer DOM were consistently enriched, with the enrichments described by a partitioning relationship, and showed evidence of decreasing enrichment with increasing wave states. In general, over the temporal and spatial scales considered, microlayer DOM variabilities in clean surfaces were not greater than equivalent bulkwater variabilities.

Stratification of microorganisms and nutrients in the surface microlayer of small freshwater ponds

Using two different surface microlayer sampling devices (the Harvey and Burzell glass plate and the Garrett screen), two microlayer fractions could be distinguished. The first was from 0 to 50 µm and the second was from 51 to 320 µm. Significantly different (p < 0.05) concentrations of dissolved nutrients between the two microlayer fractions strongly suggests stratification within the surface microlayer. This apparent stratification is also examined for phototrophs, bacteria and other material found within the surface microlayer.

Phytoplankton in marine surface microlayers

Surface microlayer phytoplankton populations were monitored to assess natural temporal and spatial variability. Microlayer samples (collected using glass plates) were compared with reference bulkwater samples over hourly, diel, and seasonal time periods on spatial scales of ~0.5 to 20 km. Microlayers were consistently depleted in chlorophyll a relative to bulkwaters in diurnal samples. Depletions had no seasonal patterns and were not influenced by dissolved nutrients or organic materials or by varying wave states. A diel pattern, with nocturnal enrichments, indicated photoinhibition of microlayer microbiota. Exceptions to these patterns occurred in naturally slicked surfaces which generally had large chlorophyll a enrichments. Disparate descriptions of microlayer phytoplankton populations in previous work probably resulted from (1) use of different sampling methods, (2) geographic variations in bulkwater phytoplankton biomass, (3) low numbers of samples, and (4) uncertain identification or definition of slick conditions.

A field evaluation of plate and screen microlayer sampling techniques

Field studies of surface microlayer sampling methods involving simultaneous use of glass plates and two depths of screens have been conducted. Intercomparisons of the two methods are based upon thicknesses of sample and amounts of dissolved organic carbon, dissolved UV-absorbing phenolic materials, chlorophyll a, ATP and particulate organic carbon and nitrogen collected. Plate samples are always thinnest, and are influenced by wave state and bulkwater temperature. Amounts of materials collected generally follow sample thicknesses. Biases toward fractions of microlayer materials are not evident in either method. It was concluded that intercomparisons of data collected separately by the two methods is inadvisable.

The application of ac polarography to the determination of surface‐active substances in seawater1

An electrochemical method based on the measurement of the capacity current at the hanging mercury drop electrode by alternating‐current polarography was developed and applied to the analysis of surface‐active substances in seawater and in sea‐surface microlayer samples. Surfactant activities of natural samples collected in the Adriatic Sea in 1978–1980 are compared with different model surfactants (Triton‐X‐100, albumin, fatty acid, humic acid, polysaccharide) and with parallel measurements by the polarographic maximum method. The shape of the capacity current‐potential curves of natural samples indicates that the adsorption effect at the electrode is produced predominantly by high molecular weight compounds. The surfactant activity corresponds to about 0.01–0.5 mg·liter−1 for bulk seawater and 0.1–2 mg·liter−1 for sea‐surface microlayer samples, relative to Triton‐X‐100. Seasonal variations in surfactant activity values at offshore stations were related to biological activity.