Organic Suspended Particles Research Articles

The earliest record of a sclerobiont assemblage from a methane-seep ecosystem (upper Silurian, Morocco)

Sclerobionts colonizing brachiopod shells derived from the oldest-known methane seep deposit (upper Silurian, Moroccan Meseta) are reported for the first time. Despite a large number of the brachiopod shells collected, all representing the atrypide species Septatrypa lantenoisi Termier, very few showed the presence of sclerobionts. The majority of the shells were taphonomically altered: worn, exfoliated and corroded. The sclerobionts are represented by cornulitid tentaculitoids and less common auloporid tabulate corals and epibiontic brachiopods. Although the observed assemblage certainly does not reflect the original taxonomic composition of the sclerobiont assemblage, it provides the first insight into the Palaeozoic encrusters inhabiting methane-seep ecosystems. As implied by the moderately 13C-depleted carbon isotope composition and simple, micrite-dominated paragenetic succession of the associated seep carbonates, the investigated community most likely represents a period of slow, diffuse fluid seepage, an interpretation consistent with the common perception of the seep-related brachiopods as non-chemosymbiotic, perhaps opportunistic seep-dwellers unable to colonize sites with more vigorous fluid flow. Likewise, the studied encrusters most likely were non-obligate inhabitants of the seep ecosystem, using the brachiopod shells as firm attachment sites and elevation above the seafloor. This colonization pattern would have probably improved their access to the prolific suspended organic particles and potentially limited their exposure to the highest environmental toxicity. As in the case of geologically much younger serpulid polychaetes, also the cornulitid tubeworms colonized the methane seeps relatively shortly after their first, Middle Ordovician appearance in the fossil record.

Virioplankton and virus-induced mortality of prokaryotes in the Kara Sea (Arctic) in summer.

Among the Arctic seas, the largest volume of river runoff (~45% of the total river-water inflow into the Arctic Ocean) enters the Siberian Kara Sea. The viral communities of the Kara Sea are important for the functioning of the marine ecosystem. Studies of virus-prokaryote interactions on the Kara Sea shelf have been conducted only in spring and autumn. Here, we investigated the abundance of free viruses, viruses attached to prokaryotes, and pico-sized detrital particles; the morphology (shape and size) of the viruses, viral infection and virus-mediated mortality of prokaryotes in early summer, i.e., during a seasonal ice melting period and maximum inflow of river-water volumes with high concentrations of dissolved and suspended organic carbon. Seawater samples for microbial analyses were collected across the Kara Sea shelf zone on board the Norilskiy Nickel as a research platform from June 29 to July 15, 2018. Abundances of prokaryotes (range (0.6-25.3) × 105 cells mL-1) and free viruses (range (10-117) × 105 viruses mL-1) were correlated (r = 0.63, p = 0.005) with an average virus: prokaryote ratio of 23.9 ± 5.3. The abundance of free viruses and viral-mediated mortality of prokaryotes were significantly higher in early summer than in early spring and autumn. Free viruses with a capsid diameter of 16-304 nm were recorded in the examined water samples. Waters in the Kara Sea shelf contained high concentrations of suspended organic particles 0.25-4.0 µm in size (range (0.6-25.3) × 105 particles mL-1). The proportions of free viruses, viruses attached to prokaryotes, and viruses attached to pico-sized detrital particles were 89.8 ± 6.0%, 2.2 ± 0.6% and 8.0 ± 1.3%, respectively, of the total virioplankton abundance (on average (61.5 ± 6.2) × 105 viruses mL-1). Viruses smaller than 60 nm clearly dominated at all studied sites. The majority of free viruses were not tailed. We estimated that an average of 1.4% (range 0.4-3.5%) of the prokaryote community was visibly infected by viruses, suggesting that a significant proportion of prokaryotic secondary production, 11.4% on average (range 4.0-34.0%), was lost due to viral lysis. There was a negative correlation between the abundance of pico-sized detrital particles and the frequency of visibly infected prokaryotic cells: r = -0.67, p = 0.0008.

Estimation of the Sizes of Suspended Organic Particles from Light-Scattering Phase Functions and Their Relationship to the Water Trophic State

Average sizes of organic particles suspended in water are calculated from measurements of light-scattering phase functions. Their correlation with the sizes of phytoplankton cells, visually determined with the use of a microscope, is derived. The relationship between the size of suspended organic particles and the water trophic state is studied. It is ascertained that the average size of suspended organic particles increases with a decrease in the water productivity (trophic state). Taking into account the correlation between the average size of organic particles suspended in water and the average size of phytoplankton cells, it was concluded that the size of phytoplankton cells increased in oligotrophic waters (low trophic state) as compared to eutrophic waters (high trophic state).

Removal of seston by Crassostrea rhizophorae (Guilding, 1828) in the Vitória bay estuarine system, Brazil

ABSTRACT The clearance of organic suspended particles by bivalve mollusks in estuarine ecosystems has been considered a critical regulating service. In Neotropical estuaries and associated mangrove ecosystems, the mangrove oyster, Crassostrea rhizophorae, is a key species in such process. To evaluate C. rhizophorae clearance rates (CRbd), biodeposit experiments were carried out at dry (2015) and wet (2016) seasons, in three sites of the Vitoria Bay Estuarine System (VBES), southeastern Brazil. The average CRbd was 0.67 L.g−1.h−1, which can be regarded as low CR. Although organic fraction predominates in the particulate matter (>60%), high estuarine salinity caused by low river discharge during prolonged regional drought, impaired oyster feeder rates. When the CRbd take into account the estimate entire mangrove oyster biomass at the VBES (3.77 × 105 kg.km−2) it yields a rate of 6.51 × 106 m3.kg−1.day−1, corresponding to a mean daily capacity of organic seston removal of 26% of the total estuarine volume. Even conservative, this result highlights the importance of mangrove oyster for the estuarine regulation, emphasizing its ecological importance and the need to sustain the critical ecosystem services of regulating estuarine environmental quality.

Determination of the size of suspended organic particles from light scattering phase function and their relationship to the water trophic state

Determination of the size of suspended organic particles from light scattering phase function and their relationship to the water trophic state

Distribution of transparent exopolymer particles (TEP) in distinct regions of the Southern Ocean.

Transparent exopolymer particles (TEP) are an abundant class of suspended organic particles, mainly formed by polysaccharides, which play important roles in biogeochemical and ecological processes in the ocean. In this study we investigated horizontal and vertical TEP distributions (within the euphotic layer, including the upper surface) and their short-term variability along with a suite of environmental and biological variables in four distinct regions of the Southern Ocean. TEP concentrations in the surface (4 m) averaged 102.3 ± 40.4 μg XG eq. L-1 and typically decreased with depth. Chlorophyll a (Chl a) concentration was a better predictor of TEP variability across the horizontal (R2 = 0.66, p < 0.001) and vertical (R2 = 0.74, p < 0.001) scales than prokaryotic heterotrophic abundance and production. Incubation experiments further confirmed the main role of phytoplankton as TEP producers. The highest surface TEP concentrations were found north of the South Orkney Islands (144.4 ± 21.7 μg XG eq. L-1), where the phytoplankton was dominated by cryptophytes and haptophytes; however, the highest TEP:Chl a ratios were found south of these islands (153.4 ± 29.8 μg XG eq (μg Chl a)-1, compared to a mean of 79.3 ± 54.9 μg XG eq (μg Chl a)-1 in the whole cruise, in association with haptophyte dominance, proximity of sea ice and high exposure to solar radiation. TEP were generally enriched in the upper surface (10 cm) respect to 4 m, despite a lack of biomass enrichment, suggesting either upward transport by positive buoyancy or bubble scavenging, or higher production at the upper surface by light stress or aggregation. TEP concentrations did not present any significant cyclic diel pattern. Altogether, our results suggest that photobiological stress, sea ice melt and turbulence add to phytoplankton productivity in driving TEP distribution across the Antarctic Peninsula area and Atlantic sector of the Southern Ocean.

Particle and structure characterization of fulvic acids from agricultural soils

Structural studies on fulvic acids (FAs) are of significant importance since FAs are involved in many environmentally important processes, such as adsorption and transportation of nutrients, trace elements, and organic pollutants. Interactions between suspended and dissolved soil components are controlled by a variety of attractive and repulsive interparticle forces influenced partially by FA properties. The aim of this paper is a detailed characterization of FAs derived from agricultural soils varied with physicochemical properties. Forty topsoils (pHKCL = 3.8–7.8, clay content = 0–6%, and TOC = 7.0–187.2 g kg−1) were collected from rural area. Fulvic acids (FAs) were isolated according to the IHSS method. The overall FA solutions were purified by nonionic macroporous acrylic ester resin (DAX-8), and the organic carbon content in FA fraction (FA-OC) was determined by a liquid C–N analyzer. The particle size diameter (PSD) and polydispersity (PDI) were analyzed by a dynamic light scattering technique, while the zeta potential (ZP) was measured using an electrophoretic light scattering method. Spectroscopic properties of FAs, including occurrence and distribution of functional groups, were investigated by near-IR spectroscopy. Agricultural soils differed substantially, with FA-OC content ranging from 0.6 to 8.8 g kg−1 that accounted for 0.5 to 22.6% of TOC. The PSD exhibited wide range of particle size (0.2 to 69.6 nm) and was characterized by different polydispersity (14–183.1%). The ZP described the behavior, and surface charge of FA particles varied from − 1.7 to + 3.3 mV. Low ZP characterized 77% of FAs and indicated the ease of aggregate formation and intermolecular connections. The measured ZP also showed that suspended organic particles of FAs had both positive and negative charges, which was confirmed by the spectroscopic analysis. The presence of negative charges on FA particle surfaces was connected with the occurrence of phenol and carboxyl groups while positive charge with amine. Detailed characterization of FAs from agricultural soils confirms their heterogeneous and complex nature. The results indicate that FAs mainly exist as small molecules that form molecular aggregates or associations in solutions. FA in a solution of a similar ionic strength may be positively or negatively charged due to its chemical structure and aggregate behavior which affects their properties in the soil.

Fish culture in indoor-tank using green water technology

Green water indoor tank culture (GWT) of Tilapia with carp is an appropriate method for commercially producing of Tilapia in substitutional of different water bodies likes ponds, lakes, cages and reservoirs etc. that have environmental constraints such as land use conflicts, source of water, water quality and sub optimal temperatures, where a green house could be used to control temperature with minimizing the all possible constraints. This study showed that the high densities and feeding rates can be maintained through continual aeration and solid removal. Ammonia is removed by phytoplankton uptake and through nitrification on suspended organic particles within the water column. In the GWT the treatment process maintain good quality, reduce the need for water exchange and maximize water use efficiency. Phytoplankton (chlorophyta, rdodophyta, chrysophyta, cryptophyta etc.) and other organisms (Such as, zooplankton) within the water column are grazed on by fishes (tilapia, rui, catla, and common carp), thereby recycling waste nutrients and lowering feed conversion ratios. A Green Water technology (GWT) in indoor tank system for fish culture was developed in Jessore University of Science and Technology. The green water was produced and cultured in indoor tank using plant leaves, Joba (Hibiscus-rosa-sinensis), then Nile tilapia, rui, catla and common carp were stocked in indoor tank systems. Regular monitoring for health check, water quality check, temperature, siphoning and oxygenation with air-stone maintained adequately in indoor environment with available sunlight penetrations. The survival rate was 100%. No artificial feed was provided from stocking to harvest. Green water tank culture of tilapia with Indian major or exotic carps indicates that GWT has potential profit due to high productivity; average 150.99±0.5 gm/tilapia within 120 days and no fertilization and feeding costs, which makes green water tank culture appropriate for widespread application.

Quantity and biochemical composition of particulate organic matter in a highly trawled area (Thermaikos Gulf, Eastern Mediterranean Sea)

Bottom trawling represents nowadays one of the most severe anthropogenic disturbances at sea, and determines large impacts on benthic communities and processes. Bottom trawling determines also local sediment resuspension and the effects of the injection of large amounts of surface sediments into the water column have been repeatedly investigated. Few studies have assessed the consequences of sediment resuspension caused by bottom trawling on the quantity, biochemical composition and bioavailability of suspended organic particles and how these eventually rival those exerted by natural storms. To provide insights on this poorly addressed issue, we investigated concentrations and biochemical composition of total and enzymatically digestible pools of particulate organic matter (POM) in the Thermaikos Gulf (Mediterranean Sea) under calm sea conditions, during intensive trawling activities, and after a severe storm. We show here that sediment resuspension caused by trawling can cause large effects on POM quantity, biochemical composition and bioavailability. Both during trawling and after the storm, the relative importance of the carbohydrate pools increased (in the upper water column) and the total lipid concentrations decreased (in the intermediate and bottom layers) when compared to values measured during calm conditions. These results would suggest that bottom trawling could inject in the upper water column POM pools more refractory in nature (&lt;em&gt;e.g&lt;/em&gt;., carbohydrates) than those present in calm or after-storm conditions. By contrast, we show also that the bioavailable fraction of biopolymeric C increased significantly during trawling in the upper water column of the shallowest stations and in the bottom water column layer of the deepest ones. These results provide evidence that bottom trawling can influence the overall trophic status of coastal waters, exerting effects similar or stronger than those caused by natural storms, though of variable amplitude depending on the water depth. Since bottom trawling is carried out worldwide and natural storms at sea can be frequent and intense, we claim for the need of assessing new adapting management strategies of bottom trawling in order to mitigate the synergistic impacts of anthropogenic and natural sediment resuspension on coastal biogeochemical cycles.

Effects of food supplies and water temperature on growth rates of two species of freshwater tropical shrimps

Summary Growth rates of individual freshwater shrimp of the species Atya lanipes and Xiphocaris elongata were measured in a second‐order stream in the Luquillo Experimental Forest in Puerto Rico over 10 years (1997–2007). Shrimp living at lower altitudes in warmer water and wider stream channels with more algal and detrital foods were predicted to grow and reproduce more rapidly. Shrimp were marked and recaptured periodically in pools located at three altitudes to determine whether temperature affected growth rates among individual A. lanipes and X. elongata. Mean annual water temperatures ranged from 20 to 24 °C with the uppermost pool being cooler than the lower pools. Mean annual growth rates for Atya and Xiphocaris were 0.27 and 0.1 mm carapace length, respectively, for all three populations. Differences in growth were partially influenced by how each species obtains its food. Atya is a filter feeder and scraper and has continuous access to suspended organic particles and biofilms. The slower growth rate for Xiphocaris elongata is most likely a result of the wider range in quality and accessibility of food resources. Differences in pool morphology and depths probably affected differences in food availability. Increased leaf litter retention in the deeper upper and lower pools probably increased shrimp growth rates, while washout of leaf litter from the relatively shallow, elongate mid‐altitude pool decreased Atya lanipes growth rates. These long‐lived, slow‐growing shrimp species transform a wide range of organic materials into their biomass. Because of the slow growth rates of these detritivores shrimp, tropical storms, hurricanes, droughts or other disturbances could have persistent, long‐term impacts on detrital processing and on the populations of their predators.

Exceptional preservation of a novel gill grade in large Cretaceous inoceramids: systematic and palaeobiological implications

AbstractOrganised mineralised structures observed in large inoceramids (valves on a metre scale) from the Late Albian, Toolebuc Formation, Australia (Inoceramus sutherlandi McCoy, 1865), and the Santonian, Niobrara Formation, USA (Platyceramus sp.), were investigated using variable pressure scanning electron microscope (SEM) with energy‐dispersive X‐ray spectroscopy (EDX), X‐ray microcomputed tomography (micro‐CT) and X‐ray diffraction (XRD) analyses. These indicate that the structures comprised a phosphate framework of aligned tubes and shallow troughs overlain perpendicularly by evenly spaced structures. In the Toolebuc Inoceramus, these are U‐shaped cross‐structures, whilst in the Niobrara Platyceramus, they comprise bundled fibre elements. Comparison with modern bivalves indicates that the observed phosphatised structures represent soft‐tissue preservation of the gills, as suggested in earlier publications. The tubes and troughs are remnants of a filamental support framework comprising ordinary and primary filaments, whilst the U‐shaped cross‐structures (I. sutherlandi) and fibrous bands (Platyceramus) represent preserved longitudinal gill musculature. Internal perforate and strand‐like fabric observed on the internal surface of some Platyceramus tubular structures suggests that the framework comprised collagen. The presence of primary and ordinary filaments in numerous unusually large plicae, in at least two lamellae, indicates that the gill structures were heterorhabdic. Each plica has at least 40 ordinary filaments, an exceptional number when compared with the maximum of 20 present in modern heterorhabdic gills. The absence of incontrovertible interfilament junctions makes it difficult to say whether inoceramids were filibranch, pseudolamellibranch or eulamellibranch. However, structures that are best attributed to intraplical junctions between filaments suggest the Inoceramidae had gills akin to those of pseudolamellibranch bivalves, although their unusually large number of filaments per plica is more reminiscent of homorhabdic eulamellibranch gills. The general form of the gill is similar to that described in some other pteriomorphs, most specifically Pteria. However, it has more complex junctions and interconnections, although these are not as intricate or pervasive as those observed in the pseudolamellibranch Ostreidae. The connections and well‐developed filament framework allowed the gill to reach its unusually large size, supporting the large size of these inoceramid species. The unusually large size of the gill and its components indicate that the organism fed on the larger suspended organic particles in the water column. It would also have been capable of processing large volumes of water quickly, leading to greater potential for food accumulation and with likely implications for respiratory efficiency. This may help explain the common association of inoceramids with oxygen‐deficient palaeoenvironments, particularly as the general structure of the inoceramid gill is very different to that observed in the commonest extant chemosymbiotic bivalves.

Characterization of the suspended organic particles released from salmon farms and their potential as a food supply for the suspension feeder, Mytilus edulis in integrated multi-trophic aquaculture (IMTA) systems

The successful utilization of aquaculture-generated organic particles as a food source for marine bivalves cultured in an integrated multi-trophic aquaculture (IMTA) system depends both on the occurrence of sufficient particles within the edible size range for the species, and determining the distribution and rate of particle dispersal around the farms. In this study we characterize the distribution of organic particulate enrichment at and around Atlantic salmon (Salmo salar) aquaculture farms in the Bay of Fundy to assess its availability to the blue mussel (Mytilus edulis) on spatial and temporal scales. Long-term temporal cycles indicate overall increases in particulate organic matter (POM) at aquaculture cage locations compared to reference locations independent of time of year. Spatially, POM levels increase 2 to 4 times over ambient levels adjacent to cages, but drop to ambient levels after distances of 10m from the cage. Daily POM levels are higher at salmon farm cages than reference locations and often correlate strongly with daily fish feeding regimes. The majority of particles from the aquaculture cages are small (1–10μm), within the utilizable size range for the blue mussel and of very high quality (up to 90% organic content). Pulses of organic enrichment from salmon aquaculture farms are a dependable and bioavailable food source for the blue mussel when grown directly within the particle plume generated from the farm.

Review of the application of the traditional Chinese medicinal herb, Ranunculus sceleratus Linn.

Ranunculus sceleratus Linn. is a wetland plant and a widely used traditional Chinese medicinal herb that has been researched intensively. It has many pharmacological effects, such as antibiosis, antiphlogosis, and the relief of articular effusion. R. sceleratus also has water purifying effects because it can adsorb large amounts of nitrogen and phosphorus, decompose suspended organic particles, and accumulate heavy metals such as Fe and Zn, while it may also be used to monitor any variation in these levels. These activities of R. sceleratus are attributable to its secondary metabolites including alkaloids, sterols, tannins, flavonoids, and tryptamine derivatives. The functional chemicals produce by R. sceleratusmight be applied to the control of harmful algae in the future. Key words: Environmental restoration, functional metabolites, potential application,Ranunculus sceleratus, traditional Chinese medicinal herb.

Microbial activity and accumulation of organic matter in the burrow of the mud shrimp, Upogebia major (Crustacea: Thalassinidea)

Microbial activity and accumulation of organic matter in the burrow of the thalassinidean mud shrimp, Upogebia major, were studied on a tidal flat along the northern coast of Tokyo Bay, Japan. The burrow of U. major is Y-shaped with an upper U-shaped part plus a lower I-shaped part. Its lower part can extend to a depth of 2 m. In the present study, we compare electron transport system activity (ETSA), bacterial abundance and organic matter content [total organic carbon (TOC), total nitrogen (TN) and chlorophyll a (chl. a)] of the burrow wall sediment with the tidal flat surface and non-burrow sediments. We also compared the U- and I-shaped part in terms of these parameters. ETSA in the burrow wall was higher than at the tidal flat surface in the warmer season, and was always higher than at surrounding non-burrow sediments. Bacterial abundance in the burrow wall was higher than at the tidal flat surface and surrounding sediment. TOC and TN contents in the burrow wall were two to three times higher than those at the tidal flat surface and non-burrow sediments, regardless of season. However, there was no significant difference in chl. a content between burrow wall and tidal flat surface. These results suggest that organic enrichment of the burrow wall is a result of organic matter particles such as phytodebris accumulation along the burrow wall. For all parameters of the burrow walls, no statistical differences were found between the two parts. Present results indicate that U. major actively transports the water containing suspended organic particles not only through the U-part but also into the deeper I-part. These indicate that burrow of the mud shrimp provides a dynamic environment for microbial community in tidal flat sediment.

Characterization of microparticles in raw, treated, and distributed waters by means of elemental and particle size analyses

The elemental composition and particle size distribution of suspended particles in raw water, treated water, and distributed water were determined to understand the behavior of particles during the water treatment-distribution process. The weight of suspended particles collected on a 0.6-microm filter was 1.1 times (raw water), 1.4 times (treated water), and 1.5 times (distributed water) that collected on a 2.7-microm filter, suggesting that smaller particles may remain after conventional water treatment. Organic suspended particles were removed less efficiently than inorganic suspended particles. After sand filtration, the Al content in the fixed suspended solids (FSS) markedly increased, indicating that either a small percentage of aluminium floc passed through during sand filtration or dissolved aluminum precipitated after sand filtration. The Mn and Fe concentrations increased after chlorination. The percentages of carbon and nitrogen in the volatile suspended solids (VSS) were roughly the same in the raw, treated, and distributed waters. The carbon/nitrogen/phosphate/VSS ratios indicated that the VSS of the suspended particles consisted of organic matter originating from microorganisms. The major constituents of the FSS in the treated and distributed waters were compounds of Fe, Al, Ca, Mg, and Mn, but these compounds accounted for only 16% or less of the FSS in raw water, indicating the existence of Si compounds. In distribution pipes, the total suspended solids concentration, especially the FSS concentration, was higher than that of water just after treatment. The Fe concentration in distributed water increased, probably due to oxidation and rusting of iron pipes.

Cladoceran body length and Secchi disk transparency in northeastern U.S. lakes

Mean cladoceran body length of 59 northeastern U.S. lakes was estimated from functional groups that broadly define taxonomic, body size, and grazing potential. Multiple regression of body length, color, and chlorophyll a or total phosphorus against Secchi disk transparency explained 72% and 83% of the variation across lakes, respectively. Analysis that included body length, color, and particulate carbon, a proxy for light backscattering and absorption by suspended organic particles, explained 85% of the variance in transparency. Body length was as important a predictor of water clarity as chemical factors. Furthermore, body length was significantly correlated to temporal variation in transparency within lakes. Because cladocerans primarily filter organic particles in size ranges having high light attenuation efficiencies, body length was consistently more strongly correlated to transparency than to chlorophyll a. Monitoring cladoceran body length should help to distinguish changes in lake transparency due to nutrient loading from changes that reflect fish population size structure and predation intensity on zooplankton. This simple size index can greatly increase the interpretative value of Secchi transparency observations to lake managers.

Bioflocculation production from lower-molecular fatty acids as a novel strategy for utilization of sludge digestion liquor

We propose the bioproduction of a bioflocculant from lower-molecular fatty acids as an innovative strategy for utilizing waste sludge digestion liquor. Fundamental studies on the production, characterization and application of a novel bioflocculant were performed. Citrobactersp. TKF04 was screened out of 1,564 natural isolates as a bacterial strain capable of a bioflocculant from acetic and propionic acids. TKF04 produced the bioflocculant during the logarithmic growth in the batch cultivation, and it could be recovered from the culture supernatant by ethanol precipitation. The fed-batch cultivation with feeding of acetic acid: ammonium 10;1 (mole) to maintain pH 8.5 led to the hyper-production of the bioflocculant. The bioflocculant was found to be effective for flocculating a kaolin suspension, when added at a final concentration of 1-10 mg/l, over a wide range of pHs (2-8) and temperatures (3-95 degrees C), while the addition of cations was not required. It could flocculate a variety of inorganic and organic suspended particles including kaolin, diatomite, bentonite, activated carbon, soil and activated sludge. These indicated that the bioflocculant possesses flocculating activity comparable or superior to that of synthetic flocculants. The bioflocculation was identified as a chitosan-like biopolymer.

Effects of photosynthesis on the accumulation of Mn and Fe by Phaeocystis colonies

The significance of Mn and Fe accumulation by Phaeocystis colonies and its control by photosynthesis were investigated by performing incubation assays with radiotracers (54Mn, 59Fe and 14C). Experiments were conducted on pure cultures of Phaeocystis globosa and on natural communities collected during a P. pouchetii bloom in the Balsfjord (subarctic Norwegian fjord) and a P. globosa bloom in the Southern Bight of the North Sea. Results indicate significant accumulation of Mn and Fe in the cultured colonies, as previously shown for Mn. Most of the Mn and Fe accumulation occurred in the mucilaginous matrix of the colonies, and the intracellular assimilation represented only ~10% of the total uptake of these trace elements. These experiments demonstrated that photosynthesis largely governed the uptake of Mn by the colonies but only slightly affected the accumulation of Fe. The positive linear relationships observed for the Balsfjord samples between the Mn uptake and the C fixation in the light suggests photosynthetic control of dissolved Mn removal to the Phaeocystis colonies. As had been predicted in earlier studies, the increase in pH and dissolved oxygen observed around and inside the colonies during the photosynthetic activity of the cells could significantly decrease Mn solubility and enhance Mn oxidation rate. However, these changes would not affect significantly the precipitation of Fe according to the thermodynamic considerations. In the highly turbid waters of the North Sea, the removal of Mn and Fe is increased by both inorganic and organic suspended particles, with no significant effect of photosynthesis on the overall uptake.

Characterization of a bioflocculant produced by Citrobacter sp. TKF04 from acetic and propionic acids

A bacterial strain, TKF04, capable of producing a bioflocculant from acetic and/or propionic acids was isolated from a biofilm formed in inside a kitchen drain. It was identified as a Citrobacter based on its morphological and physiological characteristics and the partial sequences of its 16S rRNA. TKF04 produced the bioflocculant during the logarithmic phase of growth, and the optimum temperature and pH for the bioflocculant production were 30°C and 7.2–10.0, respectively. It could utilize some organic acids and sugars for its growth as the sole carbon sources when yeast extract was supplemented; however, only acetate and propionate were found to be good substrates for the bioflocculant production. The crude bioflocculant could be recovered from the supernatant of the culture broth by ethanol precipitation and dialysis against deionized water. It was found to be effective for flocculation of a kaolin suspension, when added at a final concentration of 1–10 mg/ l, over a wide range of pHs (2–8) and temperatures (approximately 3–95°C), while the co-presence of cations (Na +, K +, Ca 2+, Mg 2+, Fe 2+, Al 3+ or Fe 3+) did not enhance the flocculating activity. It could efficiently flocculate a variety of inorganic and organic suspended particles, including kaolin, diatomite, bentonite, activated carbon, soil and activated sludge. It contained glucosamine as the major component, and the molecular weight was estimated to be between 232 and 440 kDa by gel filtration. The observation that the flocculating activity was completely lost following chitinase treatment and its analysis with a Fourier transform infrared spectrometer suggested that the bioflocculant is a biopolymer structurally—similar to chitin or chitosan.

Performance of hybrid small wastewater treatment system consisting of jet mixed separator and rotating biological contactor

This paper describes a pilot plant study on the performance of a hybrid small municipal wastewater treatment system consisting of a jet mixed separator(JMS) and upgraded RBC. The JMS was used as a pre-treatment of the RBC instead of the primary clarifier. The treatment capacity of the system was fixed at 100 m3/d, corresponding to the hydraulic loading to the RBC of 117 L/m2/d. The effluent from the grid chamber at a municipal wastewater treatment plant was fed into the hybrid system. The RBC was operated using the electric power produced by a solar electric generation panel with a surface area of 8 m2 under enough sunlight. In order to reduce the organic loading to the RBC, polyaluminium chloride(PAC) was added to the JMS influent to remove the colloidal and suspended organic particles. At the operational condition where the A1 dosage and hydraulic retention time of the JMS were fixed at 5 g/m3 and 45 min., respectively, the average effluent water quality of hybrid system was as follows: TOC=8 g/m3, Total BOD=8 g/m3, SS=8 g/m3, Turbidity=6 TU, NH4-N=7 g/m3, T-P=0.5 g/m3. In this operating condition, electric power consumption of the RBC for treating unit volume of wastewater is only 0.07 KWH/m3.