Volatile organotin compounds (butylmethyltin) in three European estuaries (Gironde, Rhine, Scheldt)

The occurrence of volatile organometallicspecies of tin was evidenced and investigatedin three major European estuaries, such as theGironde (F), the Rhine (NL) and the Scheldt(B/NL), along with the salinity gradient andfor all seasons. The most ubiquitous species,observed in surface water, were found to bemethylated forms of butyl-tin derivatives(Bu_nSnMe_4-n, n = 0–3), withconcentrations significantly higher in theScheldt (ca. 75–2000 fmol l^–1) than in theRhine (ca. 5–125 fmol l^–1) and the Gironde(ca. 5–90 fmol l^–1). Additionally,estuarine anoxic sediments were found tocontain large amount of such volatile tinspecies.The presence of volatile organic tin compoundsis then supposed to result from naturalmethylation processes of both inorganic metaland anthropogenic derivatives accumulated inthe sediments (i.e. tributyltin released fromship antifouling paintings and waste waterdischarges). These results suggest thatmicrobial mediated and/or chemical methylationmechanisms are likely to produce volatileorganotin species in anoxic estuarineenvironments. The production of volatileorganotin species is also mainly dependent onthe direct anthropogenic load of butyltincompounds within the estuary and on theresidence time of such compounds in the system.Estuarine profiles along with the salinitygradient demonstrate that all investigatedestuaries are continuous sources of volatiletin species, although these estuaries presentdifferent anthropogenic organotin discharges.In consequence, significant export of volatiletin species to the adjacent coastal waters werefound. Finally, the evaluation of the seasonalfluxes of volatile tin species to theatmosphere establishes that volatilisation is amajor sink for such compound in estuaries withlong water residence time (i.e. Scheldt, Gironde).     

The major ion chemistry of some southern African saline systems

Africa south of about 23° S has few natural athalassic lakes, saline or freshwater. South Africa, however, is rich in temporary pans, many of which are saline, while permanent saline springs occur along the coastal strip of the Namib Desert in Namibia. This paper examines the chemistry of the major ions in 67 Namibian waters, 47 of which have not previously been reported in the literature, and compares them with 66 South African waters, five of which have not previously been reported, and with saline lakes in East Africa.The highest value for total dissolved solids in South African waters was 276 g l^–1 (Koekiespan, south-western Cape) and the highest for Namibian waters were 160 g l^–1 (Hosabes, a small spring on a gypsous crust) and 302 g l^–1 (a salt pan at Oranjemund at the mouth of the Orange River). The dominant ions in fresh waters in the region are Ca²⁺ and HCO _inf3 ^– /CO _inf3 ^2– in the interior and in Namibia, and Na²⁺ and Cl⁺ on the south and east coasts. Regardless of the geochemistry of their substrata, the dominant ions in the saline waters throughout the region are Na⁺ and Cl^–. Thus differential precipitation of CaCO₃ and CaSO₄, as a result of evaporative concentration at high salinities, appears to be the determinant of the proportions of the major ions in these systems.The permanent springs on gypsous crusts along the coast of Namibia, although dominated by Na⁺ and Cl^– ions, contain considerable quantities of both Ca²⁺ and SO ₄ ^2– ions.     

Vegetative approach for improving the quality of water produced from soils in the westside of central California

Water reuse is a proposed strategy for utilizing or disposing of poor quality drainage water produced in the westside of central California. This 2-year field study evaluated the ability of two potential forage species to tolerate irrigation with water high in salinity, boron (B), and selenium (Se). The species used were: Sporobulus airoides var. salado (alkali sacaton) and Medicago sativa var. salado (alfalfa). After first year establishment with good quality water (<1 dS m^–1), the two species were furrow-irrigated with drainage effluent that had an average composition of sulfate-dominated salinity ((electrical conductivity (EC) of 6.2 dS m^–1)) B (5 mg l^–1), and Se (0.245 mg l^–1). Both crops were clipped monthly from June to October of each year. Total dry matter yields averaged between 11 and 12 mg ha^–1 for both crops irrigated with effluent for two growing seasons. Plant concentrations of Se ranged from a low of 1.3 mg kg^–1 in alkali sacaton to a high of 2.5 mg kg^–1 in alfalfa, while B concentrations ranged from a low of 60 mg kg^–1 in alkali sacaton to a high of 170 mg kg^–1 in alfalfa. Chemical composition of the soil changed as follows from preplant to post-irrigation after two seasons with drainage effluent: EC from 2.78 to 6.5 dS m^–1, extractable B from 1.9 to 5.6 mg l^–1, and no change in extractable Se at 0.012 mg l^–1 between 0 and 45 cm. Between 45 and 90 cm, EC values increased from 4.95 to 6.79 dS m^–1, extractable B from 2.5 to 4.8 mg l^–1, and no change in extractable Se at 0.016 mg l^–1. Increased salinity and extractable B levels in the soil indicate that management of soil salinity and B will be necessary over time to sustain long term reuse with poor quality water.     

The Shatt al-Arab River: A nutrient salt and organic matter source to the Arabian Gulf

The distribution of dissolved reactive phosphate, nitrate and nitrite in the waters as well as total organic carbon, total phosphorus and Kjeldahl nitrogen in the sediments of the Shatt al-Arab Estuary and the NW Arabian Gulf were studied from November 1979 to April 1980. The Shatt al-Arab waters contain 0.18 to 0.70 µg-at P-PO _inf4 ^sup3– l^–1, 26.12 to 52.39 µg-at N-N0 _inf3 ^sup– l^–1 and 0.53 to 0.70 µg-at N-NO _inf2 ^sup– l^–1, indicating that this river should be considered a source of nutrients to the Arabian Gulf. It is concluded that most of the nitrate is supplied in dissolved form, while an appreciable amount of phosphate is absorbed to fine suspended particles and released at higher salinities. Total organic carbon in surficial sediments was found to vary between 0.14% and 0.96%. These rather low values are attributed to dilution by dust fallout, which is a major cource of sediments in this area.     

Active NaCl absorption across split lamellae of posterior gills of Chinese crabs (Eriocheir sinensis) adapted to different salinities

Split lamellae of posterior gills of Eriocheir sinensis adapted to fresh water, brackish waters (9 or 18‰) or seawater (36‰) were mounted in Ussing chambers, and transepithelial short-circuit currents and conductances were measured with salines, containing approximately in vivo-like NaCl concentrations. Active sodium and chloride absorption (I_Na and I_Cl), the transcellular conductances and the leak conductance were identified with external amiloride and/or DIDS. Split gill lamellae of crabs adapted to fresh water displayed similar magnitudes of I_Na and I_Cl with 10 mmol l⁻¹ NaCl in the external medium (internally haemolymph-like NaCl saline). Augmenting external NaCl (50 mmol l⁻¹) resulted in an increase of I_Cl, whereas I_Na decreased. Split gill lamellae of crabs adapted to brackish waters (external NaCl of 125 and 225 mmol l⁻¹, respectively) showed lower currents than preparations of freshwater crabs (50 mmol l⁻¹ external NaCl). With split gill lamellae of seawater crabs no currents were detected (450 mmol l⁻¹ NaCl on both sides). The transcellular conductances showed similar changes as the currents. The leak conductance of split gill lamellae of crabs adapted to fresh or brackish waters was low (0.3–0.8 mS cm⁻²), whereas it was much higher (7 mS cm⁻²) with preparations of seawater crabs.     

Isolation of Iodide-Oxidizing Bacteria from Iodide-Rich Natural Gas Brines and Seawaters

Iodide-oxidizing bacteria (IOB), which oxidize iodide (I⁻) to molecular iodine (I₂), were isolated from iodide-rich (63 μM to 1.2 mM) natural gas brine waters collected from several locations. Agar media containing iodide and starch were prepared, and brine waters were spread directly on the media. The IOB, which appeared as purple colonies, were obtained from 28 of the 44 brine waters. The population sizes of IOB in the brines were 10² to 10⁵ colony-forming units (CFU) mL⁻¹. However, IOB were not detected in natural seawaters and terrestrial soils (fewer than 10 CFU mL⁻¹ and 10² CFU g wet weight of soils⁻¹, respectively). Interestingly, after the enrichment with 1 mM iodide, IOB were found in 6 of the 8 seawaters with population sizes of 10³ to 10⁵ CFU mL⁻¹. 16S rDNA sequencing and phylogenetic analyses showed that the IOB strains are divided into two groups within the α-subclass of the Proteobacteria. One of the groups was phylogenetically most closely related to Roseovarius tolerans with sequence similarities between 94% and 98%. The other group was most closely related to Rhodothalassium salexigens, although the sequence similarities were relatively low (89% to 91%). The iodide-oxidizing reaction by IOB was mediated by an extracellular enzyme protein that requires oxygen. Radiotracer experiments showed that IOB produce not only I₂ but also volatile organic iodine, which were identified as diiodomethane (CH₂I₂) and chloroiodomethane (CH₂ClI). These results indicate that at least two types of IOB are distributed in the environment, and that they are preferentially isolated in environments in which iodide levels are very high. It is possible that IOB oxidize iodide in the natural environment, and they could significantly contribute to the biogeochemical cycling of iodine.     

Dolomite limits acidification of a biofilter degrading dimethyl sulphide

The applicability of dolomite particlesto control acidificationin a Hyphomicrobium MS3inoculated biofilter removingdimethyl sulphide (Me₂S) wasstudied. While direct inoculationof the dolomite particles with theliquid microbial culture was notsuccessful, start-up ofMe₂S-degradation in thebiofilter was observed when thedolomite particles were mixed with33% (wt/wt) of Hyphomicrobium MS3-inoculatedcompost or wood bark material.Under optimal conditions, anelimination capacity (EC) of 1680~g Me₂S m^-3 d^-1 wasobtained for the compost/dolomitebiofilter. Contrary to a wood barkor compost biofilter, no reductionin activity due to acidificationwas observed in these biofiltersover a 235 day period because ofthe micro environmentneutralisation of the microbialmetabolite H₂SO₄ with thecarbonate in the dolomite material.However, performance of thebiofilter decreased when themoisture content of the mixedcompost/dolomite material droppedbelow 15%. Next to this, nutrientlimitation resulted in a gradualdecrease of the EC andsupplementation of a nitrogensource was a prerequisite to obtaina long-term high EC (> 250 gMe₂S m^-3 d^-1) forMe₂S. In relation to thisnitrogen supplementation, it wasobserved that stable ECs forMe₂S were obtained when thisnutrient was dosed to the biofilterat a Me₂S-C/NH₄Cl-Nratio of about 10.Abbreviations:DW – dry weight,EC – elimination capacity,Me₂S – dimethyl sulphide,OL – organic loading rate,VS - volatile solids     

Induced accumulation of triterpenoids in Scutellaria baicalensis suspension cultures using a yeast elicitor

When growth-phase cell suspension cultures of Scutellaria baicalensis were treated with 50 g of yeast elicitor preparation ml^–1, both oleanolic acid and ursolic acid transiently increased in the culture medium rather than in the cells. The maximal triterpenoid concentration was 13.7 mg l^–1 media approx. 35 h after treatment, whereas the maximum concentration was 2.1 mg l^–1 media after about 20 h following treatment with methyl jasmonate. Elicitor treatment also doubled phospholipase A₂ activity (25 pmol mg^–1 min) and the simultaneous treatment of aristolochic acid, a phospholipase A₂ inhibitor, inhibited triterpenoids accumulation as well as phospholipase A₂ activity.     

Denitrification kinetics of simulated fish processing wastewater at different ratios of nitrate to biomass

Denitrification was studied in anoxic batch cultures of a simulated fish processing wastewater at 37 r C and pH 7.5, using a denitrifying enrichment culture from fishery wastewater. Different initial nitrate to biomass ratios (So/Xo) were used: nitrate and biomass varied from 7.5 to 94.7 mg NO₃-N l^–1, and from 20 to 4300 mg volatile suspended solids l^–1, respectively. The specific maximum denitrification rate (r _m) and the cell yield (Y _{X / S}) depended on the So/Xo ratio under anoxic conditions: r _m increased from 1.2 to 1584 mg NO₃-N g^–1 VSS h^–1 and Y _{X / S} decreased from 42 to 0.03 mg VSS mg^–1 NO₃-N when So/Xo varied from 5.5 10^{– 3} to 9.3 mg NO₃-N/mg VSS. Nomenclature C_{NO3 – N} nitrate concentration, mg NO₃-N l^–1 K _S saturation constant, mg NO₃-N l^–1 r _m specific maximum denitrification rate, mg NO₃-N g^–1 VSS h^–1 So initial substrate concentration, mg l^–1 t time, h TOC total organic carbon VSS volatile suspended solids x biomass concentration, g VSS l^–1 Xo initial biomass concentration, g VSS l^–1 Y _X/S substrate to biomass cell yield, mg VSS/mg N Greek symbols: _m maximum specific growth rate of the anoxic microbial population, 1 h^–1     

Protein production from whey usingPenicillium cyclopium; growth parameters and cellular composition

Summary The growth parameters ofPenicillium cyclopium have been evaluated in a continuous culture system for the production of fungal protein from whey. Dilution rates varied from 0.05 to 0.20 h^–1 under constant conditions of temperature (28°C) and pH (3.5). The saturation coefficients in the Monod equation were 0.74 g l^–1 for lactose and 0.14 mg l^–1 for oxygen, respectively. For a wide range of dilution rates, the yield was 0.68 g g^–1 biomass per lactose and the maintenance coefficient 0.005 g g^–1 h^–1 lactose per biomass, respectively. The maximum biomass productivity achieved was 2 g l^–1 h^–1 biomass at dilution rates of 0.16–0.17 h^–1 with a lactose concentration of 20 g l^–1 in the feed. The crude protein and total nucleic acid contents increased with a dilution rate, crude protein content varied from 43% to 54% and total nucleic acids from 6 to 9% in the range of dilution rates from 0.05 to 0.2 h^–1, while the Lowry protein content was almost constant at approximately 37.5% of dry matter.Nomenclature (mg l^–1) C_o initial concentration of dissolved oxygen - (h^–1) D dilution rate - (mg l^–1) K₀₂ saturation coefficient for oxygen - (g l^–1) K_s saturation coefficient for substrate - (g g^–1 h^–1) lactose per biomass) m maintenance energy coefficient - (mM g^–1 h^–1O₂ per biomass) Q₀₂ specific oxygen uptake rate - (g l^–1) S residual substrate concentration at steady state - (g l^–1) S_o initial substrate concentration in feed - (min) t_1/2 time when C_o is equal to C_o/2 - (g l^–1) X biomass concentration - (g l^–1) X biomass concentration at steady state - (g g^–1 biomass per lactose) Y_G yield coefficient for cell growth - (g g^–1 biomass per lactose) Y_x/s overall yield coefficient - (h^–1) specific growth rate     

Development of dependence on aerial respiration in Polypterus senegalus (Cuvier)

The respiratory behaviour and partitioning of O₂ uptake between air and water were investigated in Polypterus genegalus using continuous-flow and two-phase respirometers and lung gas replacement techniques P. senegalus rarely resorts to aerial respiration under normal conditions. Partitioning of O₂ consumption depends on the activity and age of fish and the availability of aquatic oxygen. Immature fish (12–22 g) cannot utilize aerial O₂ but older fish exhibit age-dependent reliance on aerial respiration in hypoxic and hypercarbic waters. Pulmonary respiration accounts for 50% of the total requirement at aquatic O₂ concentrations of about 3.5 mg · l^–1 (or CO₂ of about 5%) and fish rely exclusively on aerial respiration at O₂ concentrations of less than 2.5 mg · l^–1. Branchial respiration is initially stimulated by hypercarbia (CO₂: 0.5–0.8%) but increased hypercarbia (CO₂ – 1%) greatly depresses (by over 90%) brancial respiration and initiates (CO₂: 0.5%) and sustains pulmonary respiration.     

By-product formation by a novel glycerol-producing yeast,Candida glycerinogenes,with different O2 supplies

Candida glycerinogenes is an aerobe which does not depend on sulphite for production of glycerol. With a sufficient O₂ supply, up to 130 g glycerol l^–1 was produced with 2.6 g acetic acid l^–1 as by-product. However, with an insufficient O₂ supply – with higher volumes of medium or at higher corn steep liquid concentrations – the glycerol concentration was lower because the by-products, ethanol, pyruvate and lactic acid, were produced in greater amounts, up to 45 g l^–1, 4.3 g l^–1, 1.6 g l^–1, respectively, whereas, less acetic acid (0.6 g l^–1) was produced. In addition, ethanol decreased to 0.4 g l^–1 and the glycerol yield improved from 34 to 50% (w/w) by adding 50 g sulphite l^–1, nevertheless, acetic acid increased to 7.8 g l^–1.     

Thermal, mixing, and oxygen regimes of the Salton Sea, California, 1997–1999

The Salton Sea is a shallow (mean depth = 8 m; maximum depth = 15 m), saline (41–45 g l^–1), intermittently mixing, 57 km long, 980 km² lake located in the arid southwestern United States. The Sea is a wind driven system, with predominant winds paralleling the long axis of the lake, being strongest in spring and weakest in summer and fall. The Sea mixed daily or nearly daily between September and January. During this cooling period, moderate to high levels of dissolved oxygen (3–11 mg l^–1) were found throughout the water column. Mean water column temperature ranged from a minimum of 13–14 °C in early January to a maximum of 30–34 °C in July–September. During most of this warming period, the Sea was thermally stratified but subject to periodic wind driven mixing events. Winds were stronger in spring 1998 than in 1997 or 1999, causing more rapid heating of the lake that year and also delaying onset of anoxic conditions in bottom waters. During summer months, mid-lake surface waters were sometimes supersatured with oxygen, and bottom waters were hypoxic or anoxic with sulfide concentrations > 5 mg l^–1. Oxic conditions (> 1 mg O₂ l^–1) often extended a few meters deeper nearshore than they did well offshore as a consequence of greater mixing nearshore. Mixing events in late summer deoxygenated the entire water column for a period of days. Consumption of oxygen by sulfide oxidation likely was the principal mechanism for these deoxygenation events. Sulfide concentrations in surface waters were 0.5–1 mg l^–1 approximately 3 days after one mixing event in mid-August 1999. These mixing events were associated with population crashes of phytoplankters and zooplankters and with large fish kills. In the southern basin, freshwater inflows tended to move out over the surface of the Sea mixing with saline lake water as a function of wind conditions. Salinity gradients often contributed more to water column stability than did thermal gradients in the southeasternmost portion of the lake.     

Limitations in substrate utilization efficiency by Zymomonas mobilis

Summary Optimal growth conditions for Zymomonas mobilis have been established using continuous cultivation methods. Optimal substrate utilization efficiency occurs with 2.5 g l^–1 yeast extract, 2.0 g l^–1 ammonium sulfate and 6.0 g l^–1 magnesium sulfate in the media. Catabolic activity is at its maximum with glucose uptake rates of 16–18 g l^–1 h^–1 and ethanol production rates of 8–9 g l^–1 h^–1, Q_g values of 22–26 and Q_p values between 11 and 13, which results in 40 g l^–1 h^–1 ethanol yields using a 100 g l^–1 substrate feed. Any increase in these parameters goes on cost of substrate utilization efficiency. Calcium pantothenate can not substitute yeast extract.Abbreviations G Glucose (%) - Pant Calcium pantothenate (mg l^–1) - D Dilution rate (h^–1) - NH₄ Ammonium sulfate (%) - M_g Magnesium sulfate (%) - S₁ Residual glucose in the fermenter (g l^–1) - S₀ Glucose feed (g l^–1) - Eth Ethanol concentration (g l^–1) - GUR Glucose uptake rate (g l^–1 h^–1) - Q_g Specific glucose uptake rate (g g^–1 h^–1) - Q_p Specific ethanol production rate (g g^–1 h^–1) - EPR Ethanol production rate (g l^–1 h^–1) - Y_g Yield coefficient for glucose (g g^–1) - Y_p Conversion efficiency (%) - C Biomass concentration (g l^–1) Present address: (Until June 1982) Institut für Mikrobiologie, TH Darmstadt, 6100 Darmstdt, Federal Republic of Germany     

Effects of tissue culture conditions and explant characteristics on direct somatic embryogenesis in Oncidium `Gower Ramsey'

The effects of tissue culture conditions and explant characteristics on direct somatic embryogenesis were studied on Oncidium `Gower Ramsey'. Embryo formation was significantly affected by explant position. Leaf tip segments had a significantly higher embryogenic response than other segments of leaves. Adaxial-side-up orientation significantly promoted embryogenesis in comparison with abaxial-side-up orientation. There was no significant effect of sucrose in a range of concentrations (10–60 g l^–1). Modified 1/2-MS medium (containing 85 mg l^–1 KH₂PO₄) supplemented with 170 mg l^–1 NaH₂PO₄ significantly promoted direct somatic embryogenesis. Peptone at 0.5 mg l^–1 gave significantly higher emrbyogenic response (80%) on leaf tips than control treatment (50%). The best response on direct embryo formation was obtained on the modified 1/2-MS medium supplemented with 10–20 g l^–1 sucrose, 170 mg l^–1 NaH₂PO₄ and 0.5 g l^–1 peptone.     

Nutrients in pore waters from Dead Sea sediments

Pore waters were separated from 50 cm-long cores of Dead Sea sediments raised from waters depths of 25, 30 and 318 m. The salinity of the pore water is close to that of the overlying water at 225–230 g l^–1 chloride. The titration alkalinity of the pore water is about 60 % of the overlying water, and sulfate is also depleted. Ammonia and phosphate concentrations are higher than those of the water column with up to 50 mg l^–1 N-NH₃ (ten times increase) and 350 µg l^–1 P-PO _inf4 ^sup3– (four to eight times increase). Early diagenetic reactions are a result of decomposition of organic matter and of water-sediment interactions, resulting in aragonite precipitation, phosphate removal to the sediments, probably by absorption on iron-oxyhydroxides followed by remobilization, reduction of sulfate and formation of iron sulfides and accumulation of ammonia. Mass balance calculations show that pore water contribute about 80% of the ammonia and 30% of the phosphate input into the Dead Sea water column. On the other hand, the sediments act as a sink for carbonate and sulfate.     

Oxidation of Methyl Halides by the Facultative Methylotroph Strain IMB-1

Washed cell suspensions of the facultative methylotroph strain IMB-1 grown on methyl bromide (MeBr) were able to consume methyl chloride (MeCl) and methyl iodide (MeI) as well as MeBr. Consumption of >100 μM MeBr by cells grown on glucose, acetate, or monomethylamine required induction. Induction was inhibited by chloramphenicol. However, cells had a constitutive ability to consume low concentrations (<20 nM) of MeBr. Glucose-grown cells were able to readily oxidize [¹⁴C]formaldehyde to ¹⁴CO₂ but had only a small capacity for oxidation of [¹⁴C]methanol. Preincubation of cells with MeBr did not affect either activity, but MeBr-induced cells had a greater capacity for [¹⁴C]MeBr oxidation than did cells without preincubation. Consumption of MeBr was inhibited by MeI, and MeCl consumption was inhibited by MeBr. No inhibition of MeBr consumption occurred with methyl fluoride, propyl iodide, dibromomethane, dichloromethane, or difluoromethane, and in addition cells did not oxidize any of these compounds. Cells displayed Michaelis-Menten kinetics for the various methyl halides, with apparent K_s values of 190, 280, and 6,100 nM for MeBr, MeI, and MeCl, respectively. These results suggest the presence of a single oxidation enzyme system specific for methyl halides (other than methyl fluoride) which runs through formaldehyde to CO₂. The ease of induction of methyl halide oxidation in strain IMB-1 should facilitate its mass culture for the purpose of reducing MeBr emissions to the atmosphere from fumigated soils.     

Thermophilic H2 production from a cellulose-containing wastewater

Cellulose in wastewater was converted into H₂ by a mixed culture in batch experiments at 55°C with various wastewaters pH (5.5–8.5) and cellulose concentrations (10–40 g l^–1). At the optimal pH of 6.5, the maximum H₂ yield was 102 ml g^–1 cellulose and the maximum production rate was 287 ml d^–1 for each gram of volatile suspended solids (VSS). Analysis of 16S rDNA sequences showed that the cellulose-degrading mixed culture was composed of microbes closely affiliated to genus Thermoanaerobacterium.     

Role of planktonic bacteria in productivity and cycling of organic matter in the Eastern Pacific Ocean

Total number, biomass, production, and respiration of bacterioplankton were measured in oligotrophic, mesotrophic and eutrophic waters of the Eastern Pacific. Total number of bacteria in the upper mixed layer and in the upper thermocline boundary layers varied from 30–60.10³ ml^-1 in oligotrophic waters to 100–400.10³ ml^-1 in mesotrophic waters of fronts and divergences, and to 1–2,5.10⁶ ml^-1 in eutrophic waters of coastal upwellings. Wet biomass varied from 5–10 mg l^-1 in oligotrophic waters, to 50–200 mg l^-1 in mesotrophic waters, and to 1–2 g m^-3 in eutrophic waters. Below the layer of maximum temperature gradient i.e. below 35–50 m, bacterioplankton density decreased 5–10 times. P/B coefficients per day were highest in the oligotrophic surface water ( 1), and lowest in the eutrophic ones (0.2–0.4). In mesotrophic waters they were intermediate (0.4–1.0). the stock of labile organic matter (LOM) accessible to microbial action varied from 0.3 to 1.6 mg Cl^-1. Its highest value occurred in the upwelling area. The stock of LOM does not noticeably decrease from the euphotic zone to a depth of 2 000 m. Its turnover time varied from 5 to 45 days in surface waters, and 30–50 years in deep oceanic waters. The role of bacterioplankton in productivity and in cycling of organic matter in surface — and deep oceanic waters is discussed.