Fraction Of Suspended Particles Research Articles

Suspended particulate matter-associated environmental corticosteroids in the Pearl River, China: Occurrence, distribution, and partitioning

Suspended particulate matter (SPM) plays an important role in the geochemical behavior and fate of organic micropollutants in aquatic environments. However, the presence of trace emerging endocrine disruptors such as environmental corticosteroids (ECs) in SPM is less well understood. This study focused on the occurrence, distribution, and partitioning of SPM-associated ECs in the Pearl River system, China. Ubiquitous particulate ECs were found in the surface water of the rivers at average concentrations (dry weight) between 0.46 ng/g (flumethasone) and 8.83 ng/g (clobetasone butyrate). The total EC (∑ECs) concentrations of the 24 selected target compounds varied from <1.03 ng/g to 62.3 ng/g, with an average and median of 17.6 ng/g and 13.7 ng/g, respectively. Higher SPM-bound EC levels were commonly observed in winter (dry season), and spatially, their relatively high contamination in urban tributary networks decreased while flowing to mainstreams and then gradually attenuated from upstream to the estuary. Despite the approximately 90 % mass distribution of ∑ECs in the aqueous phase, approximately 50 % of their effect burden was derived from the suspended particulate fractions. For the first time, in situ SPM-water partitioning coefficients (Kp) and their organic carbon-normalized ones (Koc) of ECs were determined in surface waters, and a field-derived preliminary linear equation was proposed to estimate Koc for ECs using basic physicochemical parameters n-octanol/water partitioning coefficient (Kow), which is of importance with regard to the assessment of transport, fate, and risk of these emerging hazardous chemicals. Furthermore, the significant logKoc-logKow relationship for ECs reveals that nonspecific hydrophobic partitioning is a major association mechanism between SPM and ECs. Moreover, hydrogen bonding is suggested to be a prevailing specific binding mechanism and provides more contribution to nonhydrophobic interactions between ECs and particulate organic matter than environmental estrogens.

Clogging of Infiltration Basin and Its Impact on Suspended Particles Transport in Unconfined Sand Aquifer: Insights from a Laboratory Study

A laboratory study was undertaken to investigate the physical clogging of a sand medium by injecting suspended particles (SP), with diameters ranging from 0.03 to 63.41 μm, into an infiltration basin, which was installed in a sand tank under the condition of constant head. The hydraulic conductivity (K) of the saturated porous medium was found to have decreased by 27% because of re-arrangement over the seven days of self-filtration. A clogging layer was observed on the infiltration basin bottom, probably due to straining over the stormwater infiltration stage. Particle-size analyses also indicate that retention of bigger SP led to faster straining of smaller SP, despite the small fraction of bigger SP. The clogging layer weakened the hydraulic connection between the water level in the basin and the water table of the unconfined aquifer until nearly no water could infiltrate into the aquifer. The deposition of finer SP that entered into the aquifer are governed by the hydrodynamic forces. These finer SP caused non-uniform permeability reduction of the porous medium, with an estimated 35% of permeability reduction occurring beneath the infiltration basin. However, the reduction appears to be reversible, as the fine SP deposited on the pore surfaces of the porous medium can be released or detached by the continuous horizontal hydraulic gradient. Extended tailing of the outlet breakthrough curve (BTC) also strongly supported the detachment of SP. This study focused on the effects of particles’ polydispersity and hydrodynamic forces on the hydraulic characteristics of the porous medium.

Decreased sedimentation efficiency of petro- and non-petro-carbon caused by a dispersant for Macondo surrogate oil in a mesocosm simulating a coastal microbial community

Large amounts of mucous-rich oil-containing marine snow formed in surface waters adjacent to the Deepwater Horizon spill. This marine oil snow (MOS) was implicated in oil delivery to the seafloor. Whether the use of chemical dispersants increased or decreased MOS sedimentation remains controversial. We conducted mesocosm experiments testing the effects of oil and oil plus a dispersant on MOS formation and sedimentation, in coastal seawater. The four treatments used were a surrogate Macondo oil water accommodated fraction (“WAF”), two concentrations of chemically-enhanced WAF (“CEWAF” and diluted CEWAF, “DCEWAF”) containing a dispersant and oil, and Controls (no additions). Based on radiocarbon and 13C NMR results, the presence of dispersants enhanced the amounts of petro-carbon being incorporated into the sinking oil-carrying aggregates (aka MOS). However, most of the chemically-dispersed oil preferentially partitioned into the colloidal and suspended particulate fractions rather than into the rapidly forming MOS. Thus the oil and non-petro-carbon sedimentation efficiency in treatments with a dispersant was much lower, compared to those in the Control and WAF treatments, during the four-day mesocosm experiment. Formation of MOS and its subsequent sinking sequestered the oil in two stages: first via terrestrial-derived detritus containing humic compounds, and subsequently via freshly produced material, such as exopolymeric substances produced by phytoplankton and bacteria.

An investigation of stabilization and inhibition strength of the asphaltene inhibitors by viscometric method

ABSTRACT Using inhibitors is one of the methods to prevent asphaltene formation. In the present work, we investigated the effects of three types of inhibitors on the onset of asphaltene precipitation using the viscometric method. Also in this study, a new concept called “effective adsorption point” of the inhibitor was proposed in order to determine the stabilization (dispersion) strength, by measuring the shear effects of asphaltene aggregates. The results showed that the amount of adsorbed inhibitor on the surface of asphaltene micelles, together with stabilization strength, started to increase with increasing inhibitor concentration. The results also revealed that there is a strong agreement between the calculated volume fraction of suspended particles and the effective adsorption point.

Atmospheric Pollution Caused by Particulate Metals in Central Taiwan

Dividing measured fluxes by measured airborne concentrations for varying particle size range identified dry deposition velocities of various metals. This study attempts to identify the dry deposition flux and dry deposition velocity of metallic particulates among large inhalable particles (> 10 μ m [PM10]), coarse particles (10–2.5 μ m [PM2.5 − 10]), and fine particles (< 2.5 μ m [PM2.5) at the Taichung harbor (TH) and Taichung airport (TA) sampling sites in central Taiwan from September to December in 2004 and 2005, respectively. The results indicate that dust, vehicle emissions, and marine salts are the principal sources of coarse and fine particulates at the TH sampling site. The analytical results also suggest that the average concentrations of Fe, Mn, Cu, Zn, Cr, and Mg in the total suspended particulate fraction and in coarse particles are highest at the TH sampling site. Additionally, measurement data demonstrate that the average concentrations of Mn, Cu, Zn, Cr, and Mg are also high at the TH site for all particle sizes. Both Mn and Pb concentrations resemble each other throughout all particle sizes. Results of this study further demonstrate that average TSP or PM10 concentrations measured in this study were less than Taiwan Environmental Protection Agency standard.

Seasonal and spatial trends of suspended-particle associated polycyclic aromatic hydrocarbons in urban Shizuoka, Japan

We characterized the monthly variations of 21 polycyclic aromatic hydrocarbons (PAHs) associated with suspended particles in the city of Shizuoka, Japan, over 12 months during 2001 and 2002. The fraction of fine particles (less than 2.5 μm diameter (PM2.5)) ranged from 40 to 60% of total suspended particles over the 12 months of the study, and their concentrations ranged from 19.3 to 41.7 μg/m 3. Almost all the PAHs were found in the PM2.5 fraction, in which the summed concentration (∑PAH) of the 21 PAHs ranged from 1.0 to 8.4 ng/m 3. PAH concentrations were elevated in the colder seasons, but the concentrations of the PM2.5 fraction of suspended particles were not. The composition of PAHs associated with PM2.5 changed little during the year of our study, indicating that seasonal sources such as heating have little effect. Factor analysis showed that three factors explain little of the seasonal variations in the sources of PAHs. Contour maps showed high concentrations of indicator PAHs for gasoline and diesel engine sources distributed along major roads and near factories on the outskirts of the city. We concluded that the contribution of vehicle exhausts to particle-associated PAHs is significant not only in the central city, but also in outer areas associated with major ring roads, and suggest that air pollution in outskirts of urban area also is concerned for health risk associated with the exposure.

Geochemistry of acidic Rio Tinto headwaters and role of bacteria in solid phase metal partitioning

Mining operations in the Rio Tinto area, southwest Spain, have created a historical pollution problem in the river and estuary. The fate of metals along the Rio Tinto river and estuary has been previously characterized, but little is known about transport and behaviour of metals and other elements in the headwaters of the river. The headwaters are situated approximately 100 km (north east) from Huelva at the Mediterranean Sea, with three investigated sites in this area distributed over 100 m. Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) of aqueous and solid samples revealed Ca, Fe, Mg, Na, S, Si, and Al concentrations above 0.5 mM in the stream surface waters at all sites. Trace elements included K, Cu, Li, Mn, and Zn. Concentrations of particulate elements generally accounted for less than 10% of the total load. In deeper pools along the stream, brine water was found with notably higher levels of Fe, Mg, S, Si, and Al compared to the stream water. The brine had a pH of 1.9, while the surface stream waters had pH values of about 2.7. Groundwater from the seep on the bank of the stream was found to be chemically distinct from both surface stream water and the brine. Fe, S and Al were in the solid samples at 100 mmol/kg or more. K, Na, P, Si, As, Ba, Cu, Li, and Mn were characterized by intermediate concentrations, 1.0–100 mmol/kg. A progressive downstream increase in particulate elemental concentrations was observed for P, Ba, Mn, Pb, Sr, V and Zn. Scanning electron microscopy (SEM) showed a variety of bacterial-like forms among the suspended particulates. In some instances, the bacteria appeared to be closely associated with or mineralized by inorganic precipitates. Transmission electron microscopy (TEM) revealed extensively mineralized bacterial cells in the solid sediment samples. The chemical composition of the investigated stream is attributed to inputs from groundwater and brines that likely evolve in response to evaporation during prolonged periods of moisture deficit in the summer. Planktonic bacteria were prominent components of the suspended particulate fraction in the stream; however, pH sorption edges for dissolved metals on bacteria are generally above pH 4.0, and therefore, it is unlikely that bacterial cells are an important component for transport of dissolved metals in the stream. Bottom sediments contain abundant highly mineralized bacteria with coatings of poorly crystalline iron oxyhydroxides and hydroxysulfate precipitates. Such bacterial–mineral composites likely contribute to increased solid phase partitioning of dissolved metals in the Tinto river system.

Plutonium concentrations in waters from the southern Baltic Sea and their distribution in cod ( Gadus morhua) skin and gills

The concentrations of 238Pu and 239+240Pu in water samples and suspended particulate fractions, as well as in colloidal fraction from the southern Baltic Sea are presented. The 239+240Pu concentration in surface seawater samples fall within range from 5.2 mBq·m −3 for Gdańsk Bay to 150 mBq·m −3 for Pomeranian Bay, most of which (from 52 to 96%) constituted filterable forms (≤0.45 μm). Also the distribution of plutonium in parts of cod gills and skin are presented and discussed. Over 60% of the plutonium in cod gills is accumulated in the gill arch, which suggests its metabolic origin. Most of plutonium associated with skin is in mucus, which suggests its adsorption from water.

“First Flush,” Power Law and Particle Separation Diagrams for Urban Storm-Water Suspended Particulates

Commensurate with development of in situ storm-water control and treatment is the need to quantify the delivery and granulometry of the suspended particulate fraction in storm water. Consistent with this need, this study examined the so-called “first flush” phenomenon for suspended particles with a measured range from 2 to 75 μm (typically <50 μm), the appropriateness of a single- versus multiple-power-law model of particle-number density (PND), and the application of process selection diagrams for particle separation. In comparison to a defined concentration “first flush” during the early portion of the examined rainfall-runoff events, results indicate that a disproportionately high and in some cases a continuous suspended particle delivery phenomenon that followed the hydrology of the event occurred. Such results suggest that the entire event may require treatment, not solely the commonly designated “first flush” based on indices such as suspended solids. While a single-power law reasonably represented granulometric characteristics of suspended storm-water particulates, and in theory a continuously size-based power law is the most accurate representation; within the given suspended particle-size range a multiple-power law provided reasonable simplicity and accuracy for total PND, surface area, and particulate volume. Despite a wide range of hydrologic conditions for a series of nine rainfall-runoff events examined, process selection diagrams based on the number-volume mean size (lnv) and total PND led to a similar conclusion. Based on the combination of lnv and PND in the urban catchment sedimentation in a typical transportation land use drainage facility is capable of removing 90% of particulate matter by mass within a detention time of 120 min.

Trace metal distributions in shelf waters of the northwestern Black Sea

Measurements of dissolved and leachable particulate trace metals (Mn, Fe, Co, Pb, Cd, Zn, Cu and Ni) and total particulate Mn and Fe were made on seawater samples collected from the northwestern Black Sea during the EROS 2000 expedition conducted in July–August 1995. The investigation concentrated on waters of the shelf and shelf edge, but included one deeper water (1440 m) station. In the oxic layer of the deep station, the suspended particulate fractions of Mn and Fe were a major part of the total metal mass, consistent with the presence of the “Fine Particle Layer” which forms on the shelf and spreads all over the Black Sea with intensities decreasing from the coast. Dissolved and total particulate concentrations were, respectively, Mn, 0.69–9.6, 1.2–29; Fe, 0.79–3.03, 2.3–7.4 nM. Dissolved Cu and Ni concentrations were relatively high (1–8 and 8–12 nM, respectively), and did not show any depletion in surface oxic waters, possibly as a result of strong organic complexation. Dissolved Pb concentrations (100–200 pM) were higher than were generally found on the shelf. This was attributed to atmospheric inputs combined with less efficient scavenging of metals in these low SPM waters. The distribution of dissolved Co closely resembled that of dissolved Mn reflecting coupling through oxidation of Mn. Concentrations of dissolved Cd and Zn were low in surface water (0.07–0.09 and 0.9–2.0 nM, respectively), and increases in concentrations with depth were sharply reversed around the top of the redoxcline. For most metals (Mn, Fe, Co, Pb, Cu, Cd, Zn) dissolved concentrations were low in the anoxic layers as a result of solubility by formation of, or association with, solid sulphide phases. Dissolved Ni was not affected by sulphide precipitation. At most of the shelf stations there were clear enhancements of dissolved Mn and Fe in the deepest waters, consistent with other evidence that significant benthic fluxes of these metals arise through the redox conditions in the region of the sediment-water interface. In the shelf water column, dissolved Mn and Fe concentrations ranged between 1.2 and 1350 and between 0.4 and 181 nM, respectively; the highest concentrations were found near the bottom. Particulate concentrations of Mn and Fe were high, implying high oxidation rates of Mn(II) and Fe(II) and/or high supply rates from rivers. Total particulate concentrations of Mn and Fe were 0.7–1050 and 2.3–2650 nM, respectively; the highest concentrations were found in surface and bottom waters. The distributions of particulate Mn and Fe were consistent with the isopycnal transport of Mn and Fe oxyhydroxides from the shelf by the coastal circulation. Distributions of other trace metals (Co, Pb, Cu, Ni, Cd, Zn) were considerably influenced by riverine inputs. Relatively high dissolved and available particulate metal concentrations were generally found in surface waters at stations directly influenced by the Danube River. Some trace metals (Co, Ni, Cd and Zn) were influenced by Mn and Fe cycling and increases in their dissolved concentrations occurred at a number of stations near the sediment–water interface. Dissolved and available particulate metal concentrations (nM) at stations on the shelf were, respectively: 0.171–1.80, 0.003–0.437 (Co); 0.014–0.614, 0.010–1.48 (Pb); 7.6–28.8, 0.048–3.75 (Cu); 11.0–17.5, 0.018–2.10 (Ni); 0.033–0.161, 0.003–0.063 (Cd); 1.01–8.33, 0.135–7.58 (Zn).

Temporal variations in the fractionation of the rare earth elements in a boreal river; the role of colloidal particles.

Rare earth element (REE) data from weekly sampling of the filtered (<0.45 μm) and suspended particulate phase during 18 months in the Kalix River, Northern Sweden, are presented together with data on colloidal particles and the solution fraction (<3 kDa). The filtered REE concentration show large seasonal and temporal variations in the river. Lanthanum varied between approximately 300 and 2100 pM. High REE concentration in the filter-passing fraction is related to increased water discharge and there is a strong correlation between the REE concentration, organic carbon, Al and Fe. Physical erosion of detrital particles plays a minor role for the yearly transport of particulate REE in this boreal river system. The suspended particulate fraction, which is dominated by non-detrital fractions, accounted for only 35% of the yearly total transport of La in the river. Approximately 10% of the REE were transported in detrital particles during winter. At spring-flood in May, about 30% of the LREE and up to 60% of the HREE where hosted in detrital particles. Ultrafiltration of river water during spring-flood shows that colloidal particles dominate the transport of filter-passing REE. Less than 5% of the filtered REE are found in the fraction smaller than 3 kDa. The colloidal fraction shows a flat to slightly LREE enriched pattern whereas the solution fraction (<3 kDa) show an HREE enriched pattern, compared with till in the catchment. Suspended particles show a LREE enriched pattern. Data indicate that the REE are associated with two phases in the colloidal (and particulate) fraction, an organic-rich phase (with associated Al–Fe) and an Fe-rich (Fe–oxyhydroxide) inorganic phase. The Ce-anomaly in the suspended particulate fraction in the river shows systematic variations, and can be used to interpret fractionation processes of the REE during weathering and transport. There was no anomaly at maximum spring-flood but during the ice-covered period the anomaly became more and more negative. The temporal and seasonal variations of the Ce-anomaly in the suspended particulate phase reflect transport of REE–C–Al–Fe-enriched colloids from the upper section of the till (and/or from mires) to the river at storm events.

A two-parameter Weibull function to describe airborne dust particle size distributions

A number of mathematical distributions have been proposed for the description of the particle size distribution of unconsolidated sediments. However, few studies have mathematically described aeolian dust particle size distributions. Recent work has shown mathematically how the sequential fragmentation of materials leads to a Weibull distribution. Since the breakage of aggregates by saltating grains is a primary mode of aeolian dust production, we test the hypothesis that the Weibull distribution may be used to describe airborne soil grains. Surface samples were collected from 52 sites including soils, dirt roads and roadside ditches in the Southern High Plains of west Texas. The samples were tumbled in the Lubbock dust generation, sampling and analysis system to generate a dust cloud. The particle size distribution of the dust was measured in situ by laser diffraction and PM10 concentration was determined gravimetrically (PM10 = airborne particulate matter with diameter ≤10 µm). This study demonstrated that the Weibull cumulative distribution function (c.d.f.) is an excellent choice to describe the particle size distribution of dust suspended from mineral sediment. A Weibull c.d.f. used to describe the dust cloud size distribution, accounted for 94 per cent of the variation in estimates of particles ≤50 µm diameter. The fraction of dust particles ≤10 µm diameter, as estimated using the Weibull, was not correlated to suspended PM10 concentration. However, the fraction of particles ≤10 µm was correlated with properties of the sediment from which the airborne dust was derived. As clay content increased, the total amount of suspended dust increased and the fraction of suspended particles ≤10 µm in the dust cloud decreased. Analyses of variance showed no significant differences (P < 0·05) among sampling locations (roads vs ditches vs soils) for cumulative fraction values for ≤2·5, ≤10, ≤25, ≤30 and ≤50 µm diameter particles. However, the PM10 concentration values were significantly different among dust generated from these locations. The road samples produced about twice the amount of PM10 (490 mg m−3) as the soil or ditch samples (235 mg m−3). Published in 1999 by John Wiley & Sons, Ltd.

Organic Carbon and Nitrogen Content Associated with Colloids and Suspended Particulates from the Mississippi River and Some of Its Tributaries

Suspended material samples were collected at 16 sites along the Mississippi River and some of its tributaries during July−August 1991, October−November 1991, and April−May 1992, and separated into colloid and particulate fractions to determine the organic carbon content of these two fractions of suspended material. Sample collection involved centrifugation to isolate the suspended particulate fraction and ultrafiltration to isolate the colloid fraction. For the first time, particulate and colloid concentrations and organic carbon and nitrogen content were investigated along the entire reach of the Mississippi River from above Minneapolis, Minnesota, to below New Orleans, Louisiana. Organic carbon content of the colloid (15.2 percent) was much higher than organic carbon content of the particulate material (4.8 percent). Carbon/nitrogen ratios of colloid and particulate phases were more similar to ratios for microorganisms than to ratios for soils, humic materials, or plants.

Rare-earth elements in groundwaters from the Osamu Utsumi mine and Morro do Ferro analogue study sites, Poços de Caldas, Brazil

Data are presented on rare-earth elements (REE) in prefiltered (<450 nm) near-surface and deeper groundwaters and in corresponding particulate matter (>450 nm) from the Osamu Utsumi uranium mine and the Morro do Ferro thorium-REE-deposit. Groundwaters from both sites typically contain between 1–50 μg/l of total REE, but can reach values of up to 160 μg/l in the deepest borehole F4 (U-Mine: 150–415 m). Even higher REE concentrations of up to 29 mg/l were measured in acidic, sulfate-rich near-surface waters of the same site. The chondrite-normalized REE patterns in deeper, more reducing groundwaters and in their corresponding suspended particle fractions are similar to those observed in the bedrock (phonolites), indicating that bedrock leaching and secondary mineral sorption occurred without significant fractionation between these elements, in accordance with the only small variations in the stability constants of the expected REE-sulfate complexes in these waters. Groundwaters from the unsaturated zone of both sites show a very characteristic cerium depletion (less pronounced than that observed in the corresponding suspended particulate fractions), which is most probably related to the oxidation of Ce (III) under the prevailing E h-conditions of these waters (600 to 800 mV), and to sorption/precipitation reactions of the much less soluble Ce(IV) species. Coarse particulate matter (>450 nm), composed mainly of amorphous ferric hydrous oxides, has a strong capacity for sorption of REE. This is shown by its very high REE concentrations, in some boreholes > 8,000 μg/g (total REE), and by the calculated association ratios R a (ml/g), which are in the order of 10 5 to 10 6. The implications of these findings for the migration behavior of REE in both environments are discussed.

The composition of lignin in estuarine suspended particulates and the distribution of particulate lignin in estuaries as determined by capillary gas chromatography of cupric oxide oxidation products

The contribution of lignin to the estuarine suspended particulate fraction is described in terms of its distribution over a spring tide and a neap tide in the Tamar Estuary, Southwest England and the Mersey Estuary, Northwest England. Suspended particulate samples are treated with CuONaOH at 170°C to yield simple, lignin-derived phenolic compounds, which are separated, derived and quantified by capillary gas chromatography with flame ionization detection (GC-FID). Estuarine distributions of particulate lignin are described and the sources and compositional changes of the lignin identified. Comparison of the lignin concentrations in the suspended material with those in the underlying sediment reveals that lignin is preferentially enriched in the suspended material.

Heavy metals in water and suspended particulates from an urban basin impacting Lake Ontario

Heavy metal data from routine river monitoring, storm runoff, suspended particulate (SP) and bottom sediment surveys were analyzed to assess conditions in the Don River and the potential impacts on Toronto Harbour and Lake Ontario. Metals delivery to the harbour is dominated by runoff events and metals concentrations on SP tend to decrease as suspended solids concentrations and flow increase. River particulate is significantly enriched with Cu, Hg, Pb and Zn and generally comparable to surficial Toronto Harbour bottom material and Toronto area soils. For Cu the SP fraction tends to 80–90+% during peak flows, while at low flows the operationally dissolved fraction tends to 80–90%, which may pose a hazard to river organisms at the ambient concentrations observed in water samples.

Heavy metal pollution in the Paraiba do sul River, Brazil

The methodology of critical pathway analysis successfully employed to assess the impact of the nuclear industry has been applied to evaluate the stable metal pollution in the Paraíba do sul River (PSR), Brazil. Results show that concentrations of four metals (Pb, Cu, Cr and Zn) out of eight released by an industrial park are critical. Bottom sediment and suspended particles are the most contaminated abiotic compartments. Suspended particles are the main compartment for metal transport downstream. The metal concentrations are significantly higher in the surface coatings, which are considered to be the available fraction of suspended particles and bottom sediments, than in the residual fraction. Eichornia azure and Eichornia crassipes, common aquatic plants in the area, can be employed as biological monitors for the critical heavy metals discharged into the PSR.

Dissolved and particulate phthalate esters in the River Mersey Estuary

The results of two surveys of the distributions of dissolved and suspended particulate phthalate esters in the River Mersey Estuary are reported. Significant contamination of both the water and the suspended particulate fraction with phthalate esters has been measured. Statistical analysis of the results indicates that dissolved phthalate esters behave relatively conservatively within the estuary and that their probable source is the numerous wastewater discharges in the upper estuary. Particulate associated phthalate esters show few consistent trends and it is suggested that they may be associated with specific fractions within the suspended particulate material.

Electronic measurement of single-domain magnetic particle concentration

A radio frequency oscillator with the coil of the resonant circuit wound around a tube containing a suspension of single-domain magnetic particles was employed to study the effect of the volume fraction of suspended particles on the bulk permeability with two types of suspending fluid and three different types of magnetic oxides. For a given particle and suspending fluid the permeability (measured as the inverse square oscillator frequency) of the suspension was linearly proportional to the volume fraction of particles in suspension. Volume fraction was maintained less than 10%. The level of the permeability was shifted by the suspending fluid, and the fractional increase in permeability with volume fraction was determined by the difference between the specific contribution of the particles and that of the suspending fluid to the permeability. Temperature effects on the oscillator frequency from 20 to 35 C were found to contribute less than 0.03% error in particle volume measurement by this method.

Microbial response to crude oil and Corexit 9527: SEAFLUXES enclosure study

The response of marine bacteria to Corexit 9527, with and without Prudhoe Bay crude oil labeled withn-(1-(14)C)hexadecane, in a temperate pelagic environment was monitored over 22 days using controlled ecosystem enclosures. The results indicated that Corexit and Corexit-dispersed crude oil stimulated bacterial production by serving as substrates and/or by inducing the release of organic compounds from the indigenous phytoplankton population. Highest bacterial standing stock was observed in the enclosure treated with a mixture of Corexit and crude oil, in which a large fraction of the predominant bacterivores were eliminated. Biodegradation appeared to be more significant than abiotic processes in contributing to the loss of low volatility n-alkanes in Corexit-dispersed oil. Twenty-two days following its addition, 50% of the radiotracer was recovered: 3% in the suspended particulate fraction, 10% in sedimentary material, 36% as CO2, and less than 1% in the dissolved organic pool.