Influence Of Seawater Research Articles

Growth and feeding patterns of European anchovy ( Engraulis encrasicolus) early life stages in the Aegean Sea (NE Mediterranean)

The objective of this work was to describe inter- and intra-annual variations in the environmental characteristics of the North-eastern Aegean Sea and to relate these changes to the egg and larval distributions, growth and feeding of larval anchovy ( Engraulis encrasicolus). Four cruises, two in July and two in September in 2003 and 2004 were performed. The distributions of eggs and larvae were associated with i) salinity fronts related to the Black Sea Water and ii) shallow areas of high productivity over the continental shelf, some of them with high riverine influence. The first published description of the anchovy larval diet in the Eastern Mediterranean was conducted in individuals ranging from 2.2 to 17 mm standard length. The number of non-empty guts was relatively high (between 20% and 30%), and the diet was described through 15 main items. The mean size of the prey increased with larval size, and was generally dominated by prey widths smaller than 80 μm (mainly the nauplii and copepodite stages of copepods). Small larvae positively selected copepod nauplii. As larvae grew, they shifted to larger copepod stages. At all sizes, larvae rejected abundant taxa like cladocerans. The average trophic level calculated for anchovy of all size ranges was 2.98 ± 0.16 (SE). Growth rates varied from 0.41 to 0.75 mm d −1, with the highest growth rates generally observed in September. Variability in the Black Sea Water influence and the recorded inter- and intra-annual changes in primary and secondary production, combined with marked changes in temperature over the first 20 m depth, are used to frame the discussion regarding the observed significant differences in growth rates in terms of both length and weight.

Reply to Discussion by Kaya et al. on “Swelling characteristics of bentonite in artificial seawater”Appears in Canadian Geotechnical Journal, 46(10): 1236–1238.

The authors are extremely grateful to Drs. Kaya, YukselenAksoy, and Oren for their valuable and constructive discussion. We are aware that their discussion is as follows: (1) It is known that calcium-type bentonite has lower swelling potential than sodium-type bentonite. However, the swelling-pressure test results shown in Fig. 6 in Komine et al. (2009) contradict this. (2) The authors of the discussion believe that the reported swelling pressures of bentonites are a coupled function of the water and montmorillonite content of bentonites. For their evidence, they show new figures by using the experimental data in Komine et al. (2009). Thus, from the presented data, it is difficult to reach the conclusion that the ‘‘influence of artificial seawater on the swelling characteristics of sodium-type and artificial sodium-type bentonites is low’’ and ‘‘the influence of artificial seawater on the swelling characteristics of calcium-type bentonites is more slight than sodium-type and artificial sodium-type bentonites.’’

Discussion of “Swelling characteristics of bentonite in artificial seawater”Appears in Canadian Geotechnical Journal, 46(2): 177–189.

The authors have to be congratulated for presenting such interesting research. The results are important not only in terms of buffer material to fill disposal facilities, but also in terms of understanding the effect of rising seawater level and regression of seawater inland due to excessive fresh water withdrawal at coastal areas (Yukselen et al. 2008). Thus, the discussers are very interested in the results presented in this paper, and would like to offer the following comments on the authors’ interpretations. The experimental results reveal that the maximum swelling pressures of bentonites B–E are affected by artificial seawater to varying degrees. However, results are obscure for several reasons. For example, it is known that calciumtype bentonite has lower swelling potential than sodiumtype bentonite under the same testing conditions (Azam et al. 2000). However, the comparison of maximum swelling pressures shown in Fig. 6 indicates that the maximum swelling potential of calcium-type bentonite yields a larger swelling pressure than sodium-type bentonite. Furthermore, even though the other sodium-type bentonites (B, D, E) are affected by artificial seawater, bentonite A is not affected. These results from Fig. 6 are also in apparent contradiction with Figs. 9 and 12. For example, the maximum swelling strain difference between distilled water and artificial seawater is negligible for bentonite C. On the other hand, there are appreciable strain differences in bentonite A. We wonder if the presented maximum swelling pressures of the bentonites are merely a function of the water content of the samples. To this end, we plotted the maximum swelling pressure of bentonites as a function of their average water content (Fig. D1). We also plotted the maximum swelling pressure as a function of the montmorillonite content of bentonites (Fig. D2). As seen from Fig. D1, the swelling pressure of bentonites increases linearly with average water content, implying that the reported maximum swelling pressures are also a function of moisture content. In conclusion, the results show that the maximum swelling pressure of bentonites appears to increase concomitant with montmorillonite and water contents (Fig. D2). This should be expected as the listed average water content is a function of the montmorillonite content (Fig. D3). We believe that the reported swelling pressures of bentonites are a coupled function of their water and the montmorillonite content. Thus, from the presented data it is hard to reach the conclusion that the ‘‘influence of artificial seawater on the swelling characteristics of sodium-type and artificial sodium-type bentonites is low’’ and ‘‘the influence of artificial seawater on swelling characteristics of calcium-type bentonite is more slight than sodium-type and artificial sodium-type bentonites.’’ Further evidence of the above statements is the variation of maximum swelling pressures with liquid limit. As seen from Fig. D4, the swelling pressure decreases with an increase in the liquid limit of bentonites. This appears to contradict previous research that documents swelling pressures that increase (not decrease) with an increase in liquid limit of soils (Vijayvergiya and Ghazzaly 1973; Chen 1988; Issa 1997). Additional evidence of the above stated statement comes from the authors’ own data. For example, if we take the maximum swelling strain differences between distilled water and artificial seawater at 1.4 Mg/m3 of initial density under 10 kPa vertical pressure and plot them as a function of the liquid limit of bentonites, the maximum swelling differences increase with an increase in liquid limit (Fig. D5). We chose the initial dry density of 1.4 Mg/m3 as this density is the only initial density in all tested samples. We validate our observations by plotting the observed maximum swelling strains presented in Fig. 9 as a function of the liquid limit of samples at 1.65 Mg/m3. As seen from Fig. D6, the observed maximum swelling strain is a function of liquid limit. We would appreciate the authors’ comments on our interpretation of the reported results.

Investigation of the Sediment Movement along the Tenryu–Enshunada Fluvial System Based on Feldspar Thermoluminescence Properties

The thermoluminescence (TL) properties of feldspar were used to investigate the sediment movement processes in a fluvial–coastal system. Field samples were collected at various locations along the Tenryu River and the Enshunada Coast in Japan. After a series of pretests, an appropriate TL measuring sequence was proposed for this study. Applying this approach, the natural TL intensity of feldspar grains was measured. Owing to the young age of the research area, it was assumed that the natural TL difference was ascribed to the sample depositional environment under which different possibilities of sunlight exposure exist. Surface sediment particles in the target area were classified into three groups in terms of TL intensities, i.e., river sand with large TL signals, coastal sand with medium TL signals, and dune sand with small TL signals. Stratified configuration of the Nakatajima Coastal Dune was observed from the underground-sample TL glow curves with a top, windblown, dune-sand layer; a bottom, wave-induced, coastal sand layer; and a mixing layer in between. A rather complex sediment-movement pattern in front of the Tenryu River mouth was revealed after investigation of the underwater samples. Because of the seawater influence, acting as an ultraviolet filter to sunlight, underwater samples present a larger, high-temperature TL peak than the low-temperature peak; whereas these two are almost the same for ground samples.

Continental and marine contributions to formation of mangrove sediments in an Eastern Amazonian mudplain: The case of the Marapanim Estuary

The coastline of the state of Pará in the Eastern Amazon is formed by submerged valleys occupied partially with mangroves, such as the estuary of the Marapanim River. The sediments of these mangroves are silty-clays, composed of quartz, kaolinite, illite, smectite, K-feldspar, pyrite, hematite, jarosite and halite with accessory zircon, estaurolite, tourmaline, rarely kyanite, rutile, ilmenite, sillimanite, andaluzite, topaz and anatase. Quartz, kaolinite, hematite and most accessories like zircon, estaurolite, tourmaline, rutile, kyanite, topaz, anatase and opaque minerals are inherited from the surrounding rocks (source area). The smectite, K-feldspar, pyrite, halite and jarosite are authigenic (neoformed). Halite and jarosite are currently and locally formed by intense evaporation. The sediments are formed mainly of SiO2, Al2O3 and Fe2O3, which indicates that they were subjected to intense chemical weathering, like the sediments of the Barreiras Formation. This is reinforced by the trace elements, with concentration of residual elements Zr, Cr, V, Nb, among others, while other trace elements are impoverished. The formation of K-feldspar, illite, smectite, halite and pyrite were linked to the environment of sedimentation of the mangrove, rich in organic matter and under the influence of sea water which contributed SO42-, Cl, Na+, K+, Ca2+, and Mg2+ for the formation of these minerals. In conclusion the inherited minerals, chemical composition and concentration of residual trace elements show the Barreiras Formation to be the main source of the land-derived sediments of the Marapanim mangroves.

Characterization of organic matter and depositional environment of Tertiary mudstones from the Sylhet Basin, Bangladesh

The Sylhet Basin of Bangladesh is a sub-basin of the Bengal Basin. It contains a very thick (up to 22 km) Tertiary stratigraphic succession consisting mainly of sandstones and mudstones. The Sylhet succession is divided into the Jaintia (Paleocene–late Eocene), Barail (late Eocene–early Miocene), Surma (middle–late Miocene), Tipam (late Miocene–Pliocene) and Dupitila Groups (Pliocene–Pleistocene), in ascending order. The origin of the organic matter (OM) and paleoenvironment of deposition have been evaluated on the basis of C, N, S elemental analysis, Rock-Eval pyrolysis and gas chromatography–mass spectrometry (GC–MS) analysis of 60 mudstone samples collected from drill core and surface outcrops. Total organic carbon (TOC) content ranges from 0.11% to 1.56%. Sulfur content is low in most samples. TOC content in the Sylhet succession varies systematically with sedimentation rate, with low TOC caused by clastic dilution produced by high sedimentation rates arising from rapid uplift and erosion of the Himalaya. The OM in the succession is characterized by systematic variations in pristane/phytane (Pr/Ph), oleanane/C 30 hopane, n-C 29/ n-C 19 alkane, Tm/Ts [17α(H)-22,29,30-trisnorhopane/18α(H)-22,29,30-trisnorhopane] and sterane C 29/(C 27 + C 28 + C 29) ratios during the middle Eocene to Pleistocene. Based on biomarker proxies, the depositional environment of the Sylhet succession can be divided into three phases. In the first (middle Eocene to early Miocene), deposition occurred completely in seawater-dominated oxic conditions, with abundant input of terrestrial higher plants, including angiosperms. The second phase (middle to late Miocene) consisted of mainly freshwater anoxic conditions along with a small seawater influence according to eustasic sea level change, with diluted OM derived from phytoplankton and a lesser influence from terrestrial higher plants. Oxygen-poor freshwater conditions prevailed in the third phase (post-late Miocene). Planktonic OM was relatively abundant in this stage, while a high angiosperm influx prevailed at times. T max values of ca. 450 °C, vitrinite reflectance ( R o) of ca. 0.66% and methylphenanthrene index (MPI 3) of ca. 1 indicate the OM to be mature. The lower part (middle Eocene to early Miocene) of the succession with moderate TOC content and predominantly terrestrial OM could have generated some condensates and oils in and around the study area.

The environment of the Neolithic archaeological sites in Šventoji, Western Lithuania

Geological–geomorphological, palaeobotanical (pollen and diatoms) and palaeozoological (bone) studies have been carried out in relation to archaeological excavations in Šventoji, on the coast of western Lithuania. Here, several Neolithic settlement sites existed in an area of wetlands and lake systems, which is today the Pajūris bog. Investigations show minor influence of sea water after the maximum Litorina Sea regression in the Early Neolithic, and habitats for a range of fresh/brackish water fishes existed in the area. During the Neolithic, mixed forest vegetation and wetland communities dominated the area, and development of the fauna followed this pattern, with a dominance of open woodland mammals and wetland birds which were exploited by people. Four seal species present in the region were probably decisive for the settlements in Šventoji during the Neolithic. Indications of agriculture in the area are few, but include anthropogenic species such as Plantago lanceolata from ca. 4000 cal. BC, scattered finds of cereals from ca. 3600 cal. BC, and a few bones of domesticated animals in Neolithic contexts. These indicate that some agricultural activity took place in the region, but not within the settlement area of the Pajūris bog.

The influence of sea water in oil emulsion on bearing performance

The lubricant in the bearings of ships can be easily polluted by sea water. Too much sea water may deteriorate the bearing performance and result in catastrophic failure; therefore, the lubricant should be changed regularly to prevent this. It is important to investigate the effect of adding sea water to mineral oil on the tribological performance of these bearings. In the present study, different amounts of sea water of 1, 2, and 3 per cent (by mass) were mixed with a typical mineral oil with a viscosity of 46 mm2/s at 40 °C and tested in 12 identical journal bearings under different operation conditions of rotational speed and load. For each case, the temperature within the oil film, the loci of the shaft centre, the power consumption, and the viscosity of the emulsion were measured. In parallel to these measurements, a CFD simulation was performed for the test bearings to estimate the friction force and load capacity. The experimental measurements and the computational predictions were compared. A maximum amount of sea water that can be tole-rated in the mineral oil was established for the normal working conditions of the journal bearing.

Swelling characteristics of bentonites in artificial seawater

Bentonite is currently designated for use as a buffer material for the repository of high-level radioactive waste because such a material requires swelling characteristics to seal the waste. A high-level radioactive waste disposal facility may be built in a coastal area of Japan because transportation of this waste by ships is feasible. Therefore, it is important to investigate the effects of seawater on a bentonite-based buffer. This study is intended to investigate the influence of seawater on the swelling pressure and swelling deformation characteristics of five common types of bentonite. The experiments described herein clarify the relations between the influence of seawater grade and compaction density, type of exchangeable cation, montmorillonite content of the bentonite, and vertical pressure condition. Based on experimental results, suitable specifications have been defined for a bentonite-based buffer that can withstand the effects of seawater.

Sr isotopes of the shells of the euryhaline gastropod Potamides lamarcki from the Oligocene of the French Massif Central and Paris Basin — A clue to its habitats

Euryhaline mollusks are adapted to large ranges of salinities in their life environment but are not reliable indicators of the marine or non-marine origin of dissolved ions. Many palaeogeographical controversies based on such ambiguous organisms are long lasting questions. This is the case for the some Rupelian deposits of the French Massif Central. In these deposits, the presence of a gastropod, Potamides lamarcki, has been considered to reflect various palaeoenvironments, from marine or marginal (lagoons or marine ingressions) to continental (brackish to saline lakes). As a marginal or marine fossil, it was used to reconstruct Oligocene seaways in the European Cenozoic rift system. The application of Sr isotope ratio of well preserved aragonitic fossils of P. lamarcki from Rupelian deposits in the Massif Central and in the Paris Basin is tested as a method of solving this problem. These data confirm the reliability of Sr isotopes in discriminating between euryhaline gastropods of marine origin in the Paris Basin and of continental origin in the French Massif Central. The Potamides lamarcki shells of the Paris Basin Rupelian gulf have 87Sr/ 86Sr ratios from 0.707744 ± 18 to 0.707949 ± 11, i.e. close to the Oligocene seawater range (0.70780–0.70820, McArthur et al., 2001). In contrast, the P. lamarcki shells collected in the Oligocene deposits of the French Massif Central have high 87Sr/ 86Sr ratios ranging from 0.713231 ± 16 in the Limagne basin to 0.715205 ± 13 in the Aurillac basin. These are very distinct from contemporaneous seawater and reflect the Sr isotopic compositions of local continental waters in these basins during the Rupelian. It is suggested that the Potamides lamarcki of the French Massif Central basins lived in intracontinental saline lakes rather than in lagoons with connection to seawater. Accordingly, the presence of P. lamarcki and of other euryhaline fossils cannot be taken as evidence of seawater influence in the distinct grabens of this region during the Oligocene and palaeogeographical reconstructions of the western part of the European Rift System should be reviewed.

Size variations of the amphipod crustacean Melita palmata in two Adriatic lagoons: Goro and Lesina

1 - Body length of the peracarid crustacean Melita palmata (Montagu, 1804) was measured in two Adriatic lagoons, Goro and Lesina, in order to verify the relationships between body size and ecological conditions. 2 - The size class distribution was unequal in the two lagoons. Two distinct generations were observed at Goro, one including small or medium sized juveniles and the other medium or large sized adults; most of the Lesina specimens, instead, had medium-sized bodies and the population size dispersion was lower. 3 - Mean adult sizes were significantly different among stations and between lagoons. 4 - Larger sizes were observed in stations at higher salinity, under direct seawater influence, whereas adult individuals of smaller size were present in more confined stations.

Determination of heavy metal in seawater and macroalgae of shorelines of Naples and Ischia Island, Italy

In order to develop monitoring of heavy metals (Cd2+,Cu2+,Pb2+) contamination in marine environment as well as macroalgae we have carried out this work in the Gulf of Naples and in the coastal region of Ischia island. Heavy metals were measured using the ASV (Anodic Stripping Voltammetry) analytical method. This work has given us the chance to underline the link between the state of seawater influences and the state of sessile species on the collected samples. The analyses have highlighted the bioconcentration of metals in sessile organisms.

Use of Deep Seawater for Rearing Japanese Scampi Lobster (Metanephrops japonica) Broodstock

This study investigated the influence of deep seawater on survival, larval hatching, and molting of Metanephrops japonicus broodstock. Wild caught ovigerous female lobsters were reared in a laboratory at ∼ 15°C in both deep seawater (DSW) and surface seawater (SSW). The number of females with larvae that hatched was significantly higher (χ 2 = 3.96, p < 0.05) for those reared in DSW than in SSW mainly due to excessive egg loss in females reared in SSW. The number of days from hatching to molting was significantly shorter (t = 2.22, p < 0.05) and the post-molt survival was significantly higher (χ 2 = 5.86, p < 0.05) for females reared in DSW than in SSW. Deep seawater is suitable for rearing and hatching lobsters used as broodstock.

Plume-related stable isotope compositions and fluid–rock interaction processes in the Basal Complex of La Palma, Canary Islands, Spain

Abstract Chemical and isotopic compositions of amphiboles, biotites, pyroxenes and feldspars from gabbros and basalts of La Palma, Canary Islands, were studied to determine primary, plume-related compositions and effects of late-stage water–rock interactions. All the studied amphiboles have Sr isotope ratios close to those typical for the mantle, excluding the possibility of significant seawater influence. The pyroxenes and amphiboles also have stable isotope compositions that are typical for mantle-derived phases, whereas biotites and feldspars show signs of interaction with meteoric water. On the basis of the oxygen isotopic compositions, the infiltrating meteoric water derived from precipitation at an approximate elevation of 3500 m above sea level, indicating that La Palma reached this height when the gabbro complexes were formed. The unaltered hydrogen and oxygen isotope compositions of amphiboles show a trend from normal mantle ranges to −90‰ and 5.1‰, respectively; these values are very close to compositions found in other Canary Island complexes by earlier studies, and support the theory that these compositions reflect a plume component originating from depth, rather than local phenomena.

Geochemistry of a sediment push-core from the Lucky Strike hydrothermal field, Mid-Atlantic Ridge

Hydrothermal sediment mineralogy and geochemistry can provide insights into seafloor mineralization processes and changes through time. We report a geochemical investigation of a short (22 cm) near-vent hydrothermal metalliferous sediment core from the Lucky Strike site (LS), on the Mid-Atlantic Ridge (MAR). The sediment was collected from the base of an active white smoker vent and comprises pure hydrothermal precipitates, mainly chalcopyrite, sphalerite, pyrite and barite, with negligible detrital and biogenic inputs. Geochemically, the core is enriched in elements derived from high-temperature hydrothermalism (Fe, Cu, Zn and Ba) and depleted in elements derived from low-temperature hydrothermalism (Mn), and metasomatism (Mg). The U/Fe content ratio is elevated, particularly in the deeper parts of the core, consistent with uptake from seawater associated with sulphide alteration. Rare earth elements (REE) concentrations are low and chondrite-normalized patterns are characteristic of high-temperature vent fluids with an enrichment in light REE and a pronounced positive Eu anomaly. A stronger positive Eu anomaly associated with higher La n /Sm n at the core top is controlled by barite precipitation. The hydrothermal influence on the REE decreases downcore with some evidence for a stronger seawater influence at depth. Nd isotopes also exhibit an increased detrital/seawater influence downcore. Pb isotope ratios are uniform and plot on the Northern Hemisphere Reference Line in a small domain defined by LS basalts and exhibit no detrital or seawater influence. Lucky Strike sediments are derived from high-temperature mineralization and are overprinted by a weak seawater–sediment interaction when compared with other Atlantic hydrothermal sites such as TAG. The larger seawater input and/or a larger detrital contribution in deeper layers can be explained by variable hydrothermal activity during sediment formation, suggesting different pulses in activity of the LS hydrothermal system.

A chemiluminescence biochemical oxygen demand measuring method

A new chemiluminescence biochemical oxygen demand (BOD CL) determining method was studied by employing redox reaction between quinone and Baker's yeast. The measurement was carried out by utilizing luminol chemiluminescence (CL) reaction catalyzed by ferricyanide with oxidized quinone of menadione, and Saccharomyces cerevisiae using a batch-type luminometer. In this study, dimethyl sulfoxide was used as a solvent for menadione. After optimization of the measuring conditions, the CL response to hydrogen peroxide in the incubation mixture had a linear response between 0.1 and 100 μM H 2O 2 ( r 2 = 0.9999, 8 points, n = 3, average of relative standard deviation; R.S.D. av = 4.22%). Next, a practical relationship between the BOD CL response and the glucose glutamic acid concentration was obtained over a range of 11–220 mg O 2 L −1 (6 points, n = 3, R.S.D. av 3.71%) with a detection limit of 5.5 mg O 2 L −1 when using a reaction mixture and incubating for only 5 min. Subsequently, the characterization of this method was studied. First, the BOD CL responses to 16 pure organic substances were examined. Second, the influences of chloride ions, artificial seawater, and heavy metal ions on the BOD CL response were investigated. Real sample measurements using river water were performed. Finally, BOD CL responses were obtained for at least 8 days when the S. cerevisiae suspension was stored at 4 °C (response reduction, 69.9%; R.S.D. for 5 testing days, 18.7%). BOD CL responses after 8 days and 24 days were decreased to 69.9% and 35.8%, respectively, from their original values (R.S.D. for 8 days involving 5 testing days, 18.7%).

Groundwater chemistry and ionic ratios in a western coastal aquifer of Buan, Korea: implication for seawater intrusion

Seawater intrusion was studied in a monitoring well field, located in western coastal area of Buan, Korea using groundwater chemistry and ionic ratios. Most of the study area is paddy fields apart from 200–2,500 m from the coast. The groundwaters affected by the seawater intrusion featured high levels of C1 and TDS, which are the simplest common indicators for the seawater influence. The TDS showed highly positive correlation with the other major parameters except for nitrate. High levels of NO3 at some monitoring wells indicated nitrate pollution of groundwaters due to anthropogenic origin such as septic effluents or chemical fertilizers. Based on the piper plot, it was inferred that the groundwater salinization occurred via mixing and cation exchange reaction between two end members (fresh or less affected groundwater and the seawater). Beside of the major chemical compositions, it was demonstrated that ionic ratios would be useful to delineate seawater intrusion and they include HCO3/Cl Na/Ca, Ca/Cl, Mg/Cl and Ca/SO4. Cluster analysis based on these ratios produced an equivalent result to that of using the major chemical compositions. Finally, to differentiate causes of the high salinity in groundwaters between anthropogenic origin (excessive groundwater use) and natural phenomenon (seawater intrusion wedge), consecutive monitoring of groundwater is required for multi-years.

Progression in sulfur isotopic compositions from coal to fly ash: Examples from single-source combustion in Indiana

Abstract Sulfur occurs in multiple mineral forms in coals, and its fate in coal combustion is still not well understood. The sulfur isotopic composition of coal from two coal mines in Indiana and fly ash from two power plants that use these coals were studied using geological and geochemical methods. The two coal beds are Middle Pennsylvanian in age; one seam is the low-sulfur ( 5%) Springfield Coal Member of the Petersburg Formation. Both seams have ash contents of approximately 11%. Fly-ash samples were collected at various points in the ash-collection system in the two plants. The results show notable difference in δ34S for sulfur species within and between the low-sulfur and high-sulfur coal. The δ34S values for all sulfur species are exclusively positive in the low-sulfur Danville coal, whereas the δ34S values for sulfate, pyritic, and organic sulfur are both positive and negative in the high-sulfur Springfield coal. Each coal exhibits a distinct pattern of stratigraphic variation in sulfur isotopic composition. Overall, the δ34S for sulfur species values increase up the section in the low-sulfur Danville coal, whereas they show a decrease up the vertical section in the high-sulfur Springfield coal. Based on the evolution of δ34S for sulfur species, it is suggested that there was influence of seawater on peat swamp, with two marine incursions occurring during peat accumulation of the high-sulfur Springfield coal. Therefore, bacterial sulfate reduction played a key role in converting sulfate into hydrogen sulfide, sulfide minerals, and elemental sulfur. The differences in δ34S between sulfate sulfur and pyritic sulfur is very small between individual benches of both coals, implying that some oxidation occurred during deposition or postdeposition. The δ34S values for fly ash from the high-sulfur Springfield coal (averaging 9.7‰) are greatly enriched in 34S relative to those in the parent coal (averaging 2.2‰). This indicates a fractionation of sulfur isotopes during high-sulfur coal combustion. By contrast, the δ34S values for fly-ash samples from the low-sulfur Danville coal average 10.2‰, only slightly enriched in 34S relative to those from the parent coal (average 7.5‰). The δ34S values for bulk S determined directly from the fly-ash samples show close correspondence with the δ34S values for SO4− 2 leached from the fly ash in the low-sulfur coal, suggesting that the transition from pyrite to sulfate occurred via high-temperature oxidation during coal combustion.

A spectrophotometric biochemical oxygen demand determination method using 2,6-dichlorophenolindophenol as the redox color indicator and the eukaryote Saccharomyces cerevisiae

A method to determine the spectrophotometric biochemical oxygen demand (BOD sp) was studied with high sensitivity and reproducibility by employing 2,6-dichlorophenolindophenol (DCIP) as a redox color indicator, the yeast Saccharomyces cerevisiae, and a temperature-controlling system providing a three-consecutive-stir unit. The absorbance of DCIP decreased due to the metabolism of organic substances in aqueous samples by S. cerevisiae. Under optimum conditions, a calibration curve for glucose glutamic acid concentration between 1.1 and 22 mg O 2 L −1 ( r = 0.988, six points, n = 3) was obtained when the incubation mixture was incubated for 10 min at 30 °C. The reproducibility of the optical responses in the calibration curve was 1.77% (average of relative standard deviations; RSD av). Subsequently, the characterization of this method was studied. The optical responses to pure organic substances and the influence of chloride ions, artificial seawater, and heavy metal ions on the sensor response were investigated before use with real samples. Measurements of real samples using river water were performed and compared with those obtained using the BOD 5 method. Finally, stable responses were obtained for 36 days when the yeast cell suspension was stored at 4 °C (response reduction, 89%; RSD av value for 9 testing days, 8.4%).

Phytoplankton production and community respiration in different zones of the Curonian lagoon during the midsummer vegetation period

1 - Phytoplankton structure, primary production, extracellular release of dissolved organic carbon and pelagic community respiration were investigated in different zones of the Curonian Lagoon in July 2002-2004. 2 - Phytoplankton biomass and primary production rates in different zones varied from 10.3 to 30.2 mg 1 -1 and from 530 to 2300 mg C m -3 d -1 , respectively. Photosynthetic activity during the period of investigation on average was 2 times lower in the zone of seawater influence (Klaipeda Strait) than in the central part. 3 - The greatest differences in phytoplankton biomass and the rate of primary production in the investigated areas were registered during an intensive Aphanizomenon bloom. Total phytoplankton exudation ranged from 5 to 24% (on average 12%) of the total organic carbon production. 4 - The rates of production processes exceeded decomposition processes, thus stimulating the accumulation of autochthonic organic matter in the Curonian Lagoon during the midsummer vegetation period.