Heavy metal accumulation in algae and sediments of the Black Sea coast of Turkey

The paper reports heavy metal accumulation in algae collected at four stations and in sediments at three stations on the Black Sea coast of Turkey. The metals analysed are Cd, Co, Cr, Cu, Fe, Pb, Sb and Zn. The metal content of algae increased generally (with some exceptions) from 1991 till 1993 in ?ile and Sinop. In the sediments Sb in ?ile, As in Riva, Fe, Zn in Sinop are high. According to these findings the metal pollution increased in Turkish area of the Black Sea during the years investigated.     

Preliminary environmental study of New Karvali Bay (Kavala Gulf,North Greece)

In this presentation the results of an environmental study of New Karvali bay, in Kavala Gulf, North Greece, are announced. In the studied bay the main industrial activity is a Factory of Chemical Fertilizers (FCF) and its wastes have been discharged, practically without any treatment, to the sea. The study has shown that the concentrations of phosphates and nitrates in the area around the place of the waste ejection from the factory are relatively high. Other remarkable points of the study are the presence of fluoride anions in higher level than normal and the low concentration of heavy metals (Cu, Pb and Zn).     

Vertical and spatial distribution of biogenic silica in the sediment of the gulf of Riga,Baltic Sea

The vertical and spatial concentration trends of biogenic silica (BSi) were investigated in a variety of sediment types from the Gulf of Riga. These trends were compared with the concentration of organic carbon to examine how variations in the mass sedimentation and the dissolution rate of BSi versus bacterially mediated oxidation of organic matter affect the distribution of BSi in different environments. The effects of important physical and biogeochemical factors on the distribution of BSi have also been examined.

The concentration of BSi in the surface sediment at accumulation bottoms ranges between 0.8–1.5 mmol/g with an average concentration of 1.1 mmol/g. This is about two times the concentration that has been reported in similar sediments in the open Baltic proper. Much lower concentrations were measured in erosion and transitional areas; on average around 0.2 and 0.6 mmol/g, respectively.

A comparison between recent sedimentation rate measurements (²¹⁰Pb) and concentrations of BSi within different accumulation bottoms suggests an approximate inverse relationship with each other. The importance of variation in the sedimentation rate on the surface BSi concentration is supported by the fact that higher C_org/BSi ratios are found in periphery accumulation zones close to transition areas (larger supply of carbon rich allochthonous material that dilutes settled amounts of BSi) than at accumulation bottoms in the central part of the Gulf. The C_org/BSi ratio in the sediment is always lower than in living siliceous algae which shows that the microbial degradation of organic carbon is always greater than the inorganic dissolution of BSi, irrespective of the assemblage of silica and non‐silica species.

The general vertical concentration pattern at accumulation sites showed a decreased concentration with increased depth down to 2–6 cm below seafloor where the concentration gradually equalizes. The concentration in the equalizing zone is on average about 20% lower than in the uppermost centimeter. This implies that the main part of the BSi entering the accumulation bottoms is permanently buried and that a great amount of silica already has been released during halmyrolysis. The spatial and vertical BSi trends at sites in transitional and erosional areas reflects prevailing sedimentation conditions with a low concentration in sections with a dominance of sand and gravel (no deposition of fine material) and a higher concentration in the sections containing stiff glacial clay (former accumulation area).

The average annual burial amount of BSi in the Gulf has been estimated to be around 50 000 tons of which most is buried in accumulation bottoms outside the central muddy part of the Gulf. The buried amount is about 60% of the annual river load of silica.     

Stability of a Coal Waste Artificial Reef

The feasibility of using U.K. coal-fired power station waste materials for artificial reef production is being examined. in June, 1989, an experimental artificial reef was constructed in Poole Bay, off the central south coast of the U.K., using three different mixtures of pulverised fuel ash (PFA), flue gas desulphurisation (FGD) gypsum and slurry, stabilized with cement and formed into blocks. Fifty tonnes of 40 × 20 × 20 cm blocks were formed into eight conical reef units replicating three different PFA/gypsum mixtures and one concrete control. the reef structure is 10m below chart datum on a flat sandy sea-bed.

Combustion of coal concentrates the heavy metal content in the resultant ash. the purpose of stabilization of the ash as blocks is twofold: to immobilize heavy metals (or other components) and to provide hard substratum for the attachment of organisms. to examine the effectiveness of this stabilization and hence the environmental compatibility of the block materials, heavy metal (Cd, Cr, Cu, Pb, Mn, Ni, Zn) content of the blocks has been monitored routinely over two years, to determine leaching rates. Sectional profiles indicate partial replacement of calcium content by magnesium. Associated with this there has also been some redistribution of heavy metals. Only in the case of cadmium has there been a detectable loss from the surface of blocks. Chromium and manganese concentrations appear to have increased. the metal content of the reef epibiota (including ascidians, Ascidia mentula; hydroids, Halecium spp.; bryozoans, Bugula spp. and red algae) growing on the ash blocks has been compared to that of epibiota attached to the concrete controls and surrounding sea-bed. to date no evidence of excess bioaccumulation of metals has been detected.

The physical integrity of the ash reef blocks has been maintained. There is evidence that the blocks are increasing in compressive strength.

An indication of the fishery enhancement potential of the experimental structure is given by the presence of eight commercially fished species (crustaceans and molluscs) including lobsters (Homarus gammarus).     

Sedimentary records of anthropogenic contribution to heavy metal content in Oum Er Bia estuary (Morocco)

Levels of heavy metals (Cd, Hg, Cr, Cu, Fe, Mn, Ni, Pb and Zn), organic carbon content and textural characteristics in the superficial and cored sediments of Oum Er Bia estuary have been studied. The anthropogenic fluxes of heavy metals were determined in two sediment cores collected in the estuary, facing urban sewages. A dated estuarine core from the inter-tidal area was assessed using ²¹⁰Pb and ¹³⁷Cs data. These data indicate that the mean sedimentation rates are 0.38–68 cm year^?1. The analytical results and the radio-dating of sediment cores show extremely high concentrations of Zn, Pb and Cu in the sediments that can be ascribed mostly to the discharge of the liquid effluent from the sewage since the late 1960s, decreasing towards the present day. The pollution intensity of the estuary is determined by the enrichment factors, which show that the Oum Er Bia estuary is moderately polluted to polluted.     

Effect of Pb,Cd and Cu on survival and development of Culex quinquefasciatus (Diptera: Culicidae)

ABSTRACT

The present research aimed to determine the lowest levels of three heavy metals (Pb, Cd and Cu) to which the larvae of Southern House Mosquito, Culex quinquefasciatus are susceptible in water. The study also aimed to investigate the effects of these heavy metals on the development of Cx. quinquefasciatus at concentrations set by Pakistan Environmental Protection Agency (Pak-EPA) as permissible levels for liquid industrial effluents. The 2nd instar larvae of Cx. quinquefasciatus were exposed to different concentrations of Pb, Cd and Cu and their effects on oviposition preference, egg hatching rate and larval development were studied. The LC₅₀ values of Pb, Cd and Cu were 12.6, 6.3 and 2.6?ppm, respectively. Gravid female mosquito adults deposited a significantly lower number of egg rafts in containers containing 0.50?ppm Pb or 1.0?ppm Cu in water. Each of the heavy metals in water resulted in significantly (p?<?0.05) lower egg hatching rate, prolonged time to pupation, lower pupation rate, prolonged time to adult emergence, lower adult emergence rate and higher female to male ratio. It is concluded that the 2nd instar larvae of Cx. quinquefasciatus are susceptible to Pak-EPA permissible levels of Pb, Cd and Cu in municipal and liquid industrial effluents.     

Sustainability of agricultural and wild cereals to aerotechnogenic exposure

In recent decades, the problem of the constantly increasin level of anthropogenic load on the environment is becoming more and more acute. Some of the most dangerous pollutants entering the environment from industrial emissions are heavy metals. These pollutants are not susceptible to biodegradation over time, which leads to their accumulation in the environment in dangerous concentrations. The purpose of this work is to study the sustainability of cultivated and wild plants of the Poaceae family to aerotechnogenic pollution in the soil. The content of heavy metals in couch grass (Elytrigia repens (L.) Nevski), meadow bluegrass (Poa pratensis L.) and soft wheat (Triticum aestivum) plants grown in the impact zone of Novocherkassk Power Station has been analyzed. Contamination of cultivated and wild cereals with Pb, Zn, Ni and Cd has been established. It has been shown that the accumulation of heavy metals is individual for each plant species. An average and close correlation have been established between the total HM content and the content of their mobile forms in the soil and their content in plants. For the plants studied, the translocation factor (TF) and the distribution coefficient (DC) of HM have been calculated. The TF is formed by the ratio of the concentration of an element in the root plant dry weight to the content of its mobile compounds in the soil. The DC value makes it possible to estimate the capacity of the aboveground parts of plants to absorb and accumulate elements under soil pollution conditions and is determined as the ratio of the metal content in the aboveground biomass to its concentration in the roots. TF and DC values have shown a significant accumulation of elements by plants from the soil, as well as their translocation from the root system to the aboveground part. It has been revealed that even within the same Poaceae family, cultural species are more sensitive to man-made pollution than wild-growing ones.

     

Acute and chronic toxic effect of lead (Pb) and zinc (Zn) on biomarker response in post larvae of Penaeus monodon (Fabricus, 1798)

Metal pollution produces damage to marine organisms at the cellular level possibly leading to ecological imbalance. The present investigation focused on the acute and chronic toxicity of lead (Pb) and zinc (Zn) by examining the effects of biomarker enzymes in post-larvae of Penaeus monodon (Tiger prawn). Antioxidant biomarker responses such as lipid peroxidation (LPO) and catalase (CAT) activity for Pb and Zn were determined following chronic exposure. Acute Lethal Concentration ₅₀ (LC₅₀) values observed in the study at 96?h for Pb and Zn at 5.77?±?0.32?mg?L^?1 and 3.02?±?0.82?mg?L^?1, respectively. The estimated No Observed Effect Concentration and Lowest Observed Effect Concentration values for Pb were 0.014 and 0.029?mg?L^?1 and that recorded for Zn was 0.011 and 0.022?mg?L^?1, respectively. Among the two metals studied, toxicity of Zn was found to be greater to P. monodon than Pb. The activities of antioxidant defense enzymes and total protein content differed significantly from control following exposure to both metals. Overall, the biomarker studies demonstrated that alterations in antioxidant enzymes and induction of LPO reflect the consequences of heavy metal exposure in P. monodon.     

Biomagnification of trace elements in a benthic food web: the case study of Deer Island (Northern Yellow Sea)

In this study, we investigated the concentrations of ten trace elements (Cu, Zn, Mn, Se, Ni, Cd, Cr, Pb, Hg, and As) and their trophodynamics in a benthic food chain of Deer Island, Northern Yellow Sea. The concentrations of Cu, Zn, Mn, Se, Ni, Cd, Cr, Pb, Hg, and As in the food chain ranged from 3.2 to 23.2, from 71 to 227, from 7.4 to 45.6, from 0.44 to 5.80, from 0.73 to 7.60, from 0.14 to 1.65, from 0.68 to 6.70, from 0.08 to 1.86, from 0.08 to 1.18, and from 0.24 to 3.92 mg kg^?1 dry weight, respectively. Among these trace elements, the linear regression between the log-transformed concentrations of Hg and Cd and δ¹⁵N values showed statistically significant increase (p<0.05) with the slopes of 0.134 and 0.144, indicating biomagnification of Hg and Cd occurred in the benthic food chain of Deer Island. While the linear regression for other eight trace elements (Cu, Zn, Mn, Se, Ni, Cr, Pb and As) were characterised by extensive scatter with non-significant correlation coefficients (R ²=0.002–0.235) and slopes (p=0.079–0.875), indicating there were not biomagnified or biodiluted of these trace elements.     

The effects of soil properties and temperature on the adsorption isotherms of lead on some temperate and semiarid surface soils of Iran

Sorption of metal ions by soil and clay minerals is a complex process involving different mechanisms, and controlled by different variables that can interact. The aim of this work was to study the retention mechanisms of Pb ions on different soil samples. Surface soils were sampled from Guilan and Hamadan provinces in north and northwest of Iran with temperate and semiarid climates. The adsorption isotherms of Pb on the soils have been studied at 15, 27 and 37°C. The adsorption data for different soils were fitted into Langmuir and Freundlich models. Temperate soil samples had higher clay content, cation exchange capacity, dichromate (oxidable) organic carbon, total Kjeldahl-nitrogen, biological activity, amorphous and crystalline Fe and Al, but semiarid soil samples had higher sand content, pH, equivalent calcium carbonate, available P and K. Lead adsorption data obtained from semiarid soils against those obtained from temperate soils were better fitted in both Langmuir and Freundlich models. Langmuir constants Q ₀ for Pb adsorption in semiarid soils were considerably lower than those for Pb adsorption in temperate soils. However, the binding energy (K _L) of Pb and Freundlich constant n were higher for data of semiarid soils. The effect of temperature on the Pb adsorption was positive especially in temperate soils; however, soil properties had higher effects on Pb adsorption.     

Levels of heavy metals in blue whiting caught from the eastern Black Sea area of Turkey

This paper presents data on the concentrations of 5 metals, copper (Cu), cadmium (Cd), iron (Fe), zinc (Zn) and lead (Pb) in Blue Whiting sampled from the Eastern Black Sea coast of Turkey. The highest metal concentrations of Cu, Cd, Fe, Zn and Pb were recorded in Blue Whiting with the values of 2.71, 0.601, 14.137, 15.322 and 1.078 μg g^‐1 dry weight, respectively. On average the metal concentrations in Blue Whiting followed the order of Zn > Fe > Cu > Pb > Cd. Temporal differences of concentrations of these metals were significant (p < 0.05). Spatial fluctuations of Cu, Cd, Fe, Zn and Pb concentrations in Blue Whiting were also significant (p < 0.01). It was found that the concentrations of Cu, Cd, Fe, Zn and Pb in the muscle in Blue Whiting were below the limit of Public Health Regulation in Turkey.     

Storm-induced transfer of particulate trace metals to the deep-sea in the Gulf of Lion (NW Mediterranean Sea)

In order to calculate budgets of particulate matter and sediment-bound contaminants leaving the continental shelf of the Gulf of Lion (GoL), settling particles were collected in March 2011 during a major storm, using sediment traps. The collecting devices were deployed in the Cap de Creus submarine canyon, which represents the main export route. Particulate matter samples were analyzed to obtain mass fluxes and contents in organic carbon, Al, Cr, Co, Ni, Cu, Zn, Cd, Pb and La, Nd and Sm. The natural or anthropogenic origin of trace metals was assessed using enrichment factors (EFs). Results are that Zn, Cu and Pb appeared to be of anthropogenic origin, whereas Ni, Co and Cr appeared to be strictly natural. The anthropogenic contribution of all elements (except Cd) was refined by acid-leaching (HCl 1 N) techniques, confirming that Zn, Cu and Pb are the elements that are the most enriched. However, although those elements are highly labile (59–77 %), they do not reflect severe enrichment (EFs <4). Most particles originate from the Rhone River. This has been confirmed by two different tracing procedures using rare earth elements ratios and concentrations of acid-leaching residual trace metals. Our results hence indicate that even in this western extremity of the GoL, storm events mainly export Rhone-derived particles via the Cap de Creus submarine canyons to the deep-sea environments. This export of material is significant as it represents about a third of the annual PTM input from the Rhone River.     

Bioaccumulation of heavy metals by bivalves from Lim Fjord (North Adriatic Sea)

Trace metal concentrations (Zn, Cd, Pb and Cu) were studied in two different bivalve species of the same age, the mussel Mytilus galloprovincialis, Lmk., and the oyster Ostrea edulis, Linnaeus, which had been grown in the water of Lim Fjord, North West Yugoslavia (Peninsula Istria), i.e. under the same physicochemical conditions. The study offers a realistic view on the metal accumulation ability of oysters and mussels. The distribution of trace metals over the different organs and the edible parts of the mussels and oysters, collected in June 1979, was determined and is discussed in detail. The results are supported by the determination of the trace metal levels in the dissolved state and in the suspended material in the ambient sea water of the bivalves. Concentration factors for zinc, cadmium, lead and copper in the mussels of: 95 000, 9 100, 1 500 and 4 000; and in the oysters of: 95 500, 30 400, 3 400 and 64 500 were found, respectively. The values were evaluated comparing the metal concentration in the bivalve soft part and the dissolved trace metal levels in the adjacent water.     

Polychlorinated Biphenyls (Pcbs) Pollution in Sea of Japan

Abstract

Deep waters of the Sea of Japan and surface waters of the Pacific Coast of Honshu and the northeast Sea of Japan were analysed for polychlorinated biphenyls (PCBs) pollution. the ΣPCB concentrations in solution in the Sea of Japan (50–3000 m) were between 140 and 1230 fg dm_?3. the space-integrated surface water concentration near the Pacific coast of northern Honshu was 140 fg dm_?3and for the surface water of the Sea of Japan was 230 fg dm_?3. Based on these analyses four water masses were deduced in the Sea of Japan during the summer months. It is shown for the first time in the Sea of Japan that polychlorinated biphenyls are excellent chemical indicators of not only the anthropogenic pollution, but also water masses.     

Response of roselle (Hibiscus sabdariffa) to heavy metals contamination in soils with different organic fertilisations

The response of green roselle (Hibiscus sabdariffa) to Cu/Pb contamination and manure application in soil was investigated using pot experiments. Subsamples of a mineral soil were treated with increasing doses (0–500 mg kg^?1) of Cu/Pb only and/or amended (at 10% w/w) with poultry or swine manure. Roselle plants were grown, monitored for changes in growth rate and post-harvest aboveground dry biomass and tissue Cu/Pb concentrations were determined. The plants were typically greenish with linear growth profiles at all metal doses, indicating some level of tolerance. Dry biomass yields decreased as metal dose increased. Poultry manure enhanced roselle biomass yields better than swine manure. Tissue Cu/Pb concentrations increased linearly as metal doses increased in unamended soils; whereas nonlinear responses were observed in manure-amended soils. Soil-to-plant transfer factors, T _f (%) indicated that Cu (13≤T _f (% )≤60) was more phytoavailable to roselle than Pb (11≤T _f (% )≤20). Tissue metal concentrations were modelled from soil pH, organic matter, plant available and pseudototal metal; but the models appeared more reliable with plant available metal as a covariate than with pseudototal metal content. These observations may become useful whenever phytoextraction is the remedial option for soils moderately contaminated by toxic metals.     

The lead content and isotopic composition of british coals and their implications for past and present releases of lead to the UK environment

More than 60 coal samples, predominantly from the principal coalfields of England and Wales (25) and Scotland (30), were analysed for lead by AAS and for stable lead isotopes by ICPMS. While the average lead content of Scottish coal, 23.9mg kg^–1, was more than double that of coal from England and Wales, 11.0mg kg^–1, the corresponding mean ²⁰⁶Pb/²⁰⁷Pb ratios (± 1 s.d.) were nearly identical, at 1.181±0.011 and 1.184±0.006, respectively. In the light of the lead isotopic signatures of British coals and of both indigenous (²⁰⁶Pb/²⁰⁷Pb 1.17) and imported Australian (²⁰⁶Pb/²⁰⁷Pb 1.04) lead ores, an approach based on estimated lead emissions from these sources and the deconvolution of the historical lead and ²⁰⁶Pb/²⁰⁷Pb records preserved in lake sediments, peat bogs and archival herbage material indicates that coal combustion became an increasingly significant contributor to atmospheric lead deposition in the UK during the period 1830–1930, especially after the onset of Englands decline as a major location of lead mining and smelting in the late19th Century. Since 1930 and the introduction of leaded petrol, the atmospheric ²⁰⁶Pb/²⁰⁷Pb ratio in the UK has been strongly influenced by carexhaust emissions of comparatively ²⁰⁶Pbdepleted lead of predominantly Australian origin, counterbalanced to some extent by coalcombustion emissions of lead, although these have fallen dramatically since the mid1950s. Nevertheless, with the introduction and substantial uptake of unleaded petrol in the UK during the last decade, even the declining releases from coal, along with contributions from other sources, are continuing to affect the atmospheric lead content and ²⁰⁶Pb/²⁰⁷Pb ratio.     

Changes in chemical forms of lead in temperate and semiarid soils in sterile and unsterile conditions

Sequential extraction has been used as a suitable method for fractionation of chemical forms of trace elements and study of their plant availability. Surface soils were sampled from Guilan and Hamadan provinces in north and northwest of Iran with temperate and semiarid climates. The chemical forms of Pb in the Pb(NO₃)₂-treated (400 μg Pb g⁻¹) soils have been studied in solid state incubation (FC) at 27°C in sterile and unsterile conditions. After 20 min and 3600 h a sequential extraction scheme was also used to fractionate Pb of incubated samples into soluble-exchangeable (Sol-Exch), carbonates associated (ACar), organic matter associated (AOM), Mn oxide associated (AMnOx), Fe oxide associated (AFeOx), and residual (Res) forms. Temperate soil samples had higher clay content, cation exchange capacity (CEC), dichromate oxidable organic carbon (OC), total Kjeldahl-nitrogen (TN), biological activity, amorphous and crystalline Fe and Al, but semiarid soil samples had higher sand content, pH, equivalent calcium carbonate (ECC), available P and K. Soil lead fractionation revealed that in both groups of soils Pb largely changed to exchangeable, carbonates associated and organic associated forms after 20 min. The chemical forms of Pb differed widely among soils after 3600-h incubation. The conversion rate of Pb from more available forms to less available forms was higher in temperate soils with higher Fe–Mn oxides and OM contents compared to semiarid soils. In temperate soils after 3600-h incubation, greater content of Pb was observed in Res (68%), AOM (14%), ACar (7%), and AMnOx (5%) fractions. However, in semiarid soils greater content of Pb was observed in Res (61%), ACar (16%), Sol-Exch (8%), and AOM (8%) fractions. The sum of AMnOx and AFeOx chemical forms for Pb in semiarid soils compared to temperate soils was lower. It was only 7% against 9% in temperate soils. Soil microorganisms in unsterile soils had significant effect on AOM, AFeOx and Res fractions of Pb. They not only increased AOM and AFeOx fractions of Pb in soils but also decreased Res fraction of Pb significantly.     

Hydrographic and biological aspects of algal bloom in the Adriatic Sea in 1988

The interaction of hydrological, chemical and biological factors in a defined time may cause an excess bloom of phytoplankton in an ecosystem, which can persist over a long period or occur from time to time.

This phenomenon has been recorded from the northern Adriatic and coastal enclosed basins along the eastern Adriatic coast (Ka?tela Bay, Split) for a long time now.

During 1988 this phenomenon of increased production was recorded from almost the entire northern and middle Adriatic with some traces even in its southern part. Some preliminary results for that period point to the fact that this was caused very likely by exceptionally warm and dry weather, with no significant precipitations and wind. Such conditions affect horizontal and vertical stratification of water masses.

High photosynthetic radiation, increased quantities of alochthonous organic matter, either in the form of particulate or dissolved organic matter, either in the form of particulate or dissolved organic carbon (POC or DOC), influx of nutrients (via rivers, municipal sewage or upwelling) are the main causes of sudden bloom and rapid reproduction rate of phytoplankton species (Diatoms) to the large quantities to which the pollution of the entire coastal area is due.     

Arbuscular mycorrhiza confers lead tolerance and uptake in Miscanthus sacchariflorus

The effects of an arbuscular mycorrhizal fungi (AMF) association on the growth, survival capabilities, nutrients and lead (Pb) uptake of Miscanthus sacchariflorus under different Pb concentrations were studied in the form of pot cultures. The treatments comprised inoculation or non-inoculation of the AMF, Gigaspora margarita, and the addition of three Pb concentrations to the soil (0, 100 and 1000?mg?kg^?1). The addition of Pb significantly decreased mycorrhizal colonisation. The inoculation of AMF with Pb increased chlorophyll content, Fv/Fm, total dry mass, indole-3-acetic acid (IAA), total nitrogen, and total phosphorus, whereas H₂O₂ level, indole-3-acetic acid oxidase (IAAO) activity, and peroxidase (POD) activity were low compared to those in the non-inoculated treatments. Moreover, the application of AMF together with Pb doses induces concentrations of Pb in the plant, where the higher dose of Pb (1000?mg?kg^?1) induces a lower content of Pb in the aerial part of the plant but a higher content in the root. G. margarita enhanced the tolerance of M. sacchariflorus against Pb toxicity, and facilitated the accumulation of Pb in the plant roots, whereas translocation to the shoots was inhibited at the highest dose Pb (1000?mg?kg^?1). However, in contaminated soil, the Pb removal capability of M. sacchariflorus with AMF was remarkable.     

Phaeocystis pouchetii blooms in the East Frisian coastal waters (German Bight,North Sea)

In 1982 and 1983, blooms of the planktonic alga Phaeocystis pouchetii were studied in the East Frisian coastal waters off Norderney, FRG. Morphological variability of the colonies, population development, effects on inorganic nutrient and oxygen budget, and the role in the seasonal plankton bloom sequence were investigated. in both years two separate Ph. pouchetii blooms occurred in late spring and early summer that were formed by the globosa-type exclusively. The pouchetii-type was only present during the interval between the first and second blooms in 1982. Growth conditions for Ph. pouchetii seem to be most favourable after a breakdown of a diatom bloom when the silicate reserves have been exhausted, phosphate concentrations are relatively low, but a rich supply of dissolved inorganic nitrogen is available. Contrary to diatom blooms, Ph. pouchetii blooms result in a high production of particulate organic carbon (POC). Another characteristic is the release of great amounts of dissolved organic substances, which cause extensive sea foam formation during the peaks and the subsequent breakdown of the blooms. Due to increased assimilation during mass development and intense disintegration after the breakdown, variations of the oxygen content of the water are significant. Presumably the intensity of blooms has increased in the past decade as indicated by sea foam formation which has actually been excessive in some years.