Showing papers on "Particulates published in 1987"

Modulation of the particulate organic carbon flux to the ocean by a macrotidal estuary: Evidence from measurements of carbon isotopes in organic matter from the Gironde system

Abstract: The isotopic composition of the organic carbon of the suspended particulate matter in the Gironde estuary and the Biscay shelf has been measured on a seasonal basis from 1977 to 1982. The δ13C values show a progressive change along the estuary and permit an estimate of the proportion of terrestrial carbon in each sample. It is estimated from these data that up to 80% of the continental POC is mineralized in the estuary and 3–16% of the riverborne flux is exported to the shelf.

Fuel sulfur reduction for control of diesel particulate emissions

Abstract: The impact of diesel fuel sulfur reduction on directly-emitted and secondary atmospheric particulate is evaluated by experiment and analysis. Experimental evidence shows that fuel sulfur conversion rate to particulate sulfate is linear down to zero sulfur level. Analysis shows that sulfur-derived particulate accounts for the vast majority of atmospheric particulate from diesel engines. Consequently, fuel sulfur reduction would have a far greater impact in reducing atmospheric particulate burden than any other diesel engine particulate control strategy.

Nitrogen and sulfur emissions from the burning of forest products near large urban areas

Abstract: Airborne measuremens of trace gases and particles in the smoke from a prescribed burn of forest products in the Los Angeles basin show significantly higher emissions of NOx, SO2, and particulate NO3 than do measurements in smokes from the burning of biomass in rural areas. It is postulated that the high emissions are due to the revolatilization of previously deposited pollutants. Implications for pollutant source inventories and the nuclear winter hypothesis are briefly discussed.

Method and apparatus to dispose of particulates separated-off via an exhaust gas filter of an internal combustion engine

Abstract: A method and apparatus for disposing of particulate matter retained in an exhaust gas filter of an internal combustion engine, using an electric current source. For the purpose of good auxiliary energy utilization and minimization of equipment complexity, ignition and combustion of the particulates are initiated by the flow of current through the particulate matter itself (the particulates themselves serving as an electrical heating conductor). A suitable electrode configuration is provided to supply the ignition energy to the filter element. The electric input for the combustion of the particulates is applied via an impressed power supply.

Ammonia, the dominant base in the remote marine troposphere: a review

Abstract: Ammonia appears to be the dominant base in the remote marine troposphere, yet its role inatmospheric acid-base chemistry is not well understood. The physical and chemical interactionsof ammonia with acidic species is complicated by its presence in the gas and particlephases and in cloud-, rain- and seawater. This review summarizes the reported ammoniaconcentration data in these 5 phases as well as existing sampling and analysis methods. Anattempt is made to compare these data using equilibrium and scavenging calculations. Thelowest measured ammonia gas phase concentrations appear to be consistent with reportedsulfate and ammonium concentrations in the particulate phase. The high gas phase concentrationsof ammonia found in older data appear to be a result of sampling artifacts. Reportedammonium particle and rainwater data also appear to be consistent with each other. Calculations suggest that ammonia may be in equilibrium between the gas phase and theOcean surface. To confirm or refute these conclusions, the simultaneous measurement ofammonia and relevant acidic species in all 5 phases is needed. DOI: 10.1111/j.1600-0889.1987.tb00203.x

Organic matter fluxes and the sites of oxygen consumption in deep water

Abstract: Sediment trap experiments at various stations in the Pacific and Antarctic Ocean compare observed particulate organic carbon fluxes with those obtained indirectly from vertical profiles of dissolved oxygen in the Pacific deep water. The observed carbon fluxes are characterized by large spatial variation and small vertical variation. The organic carbon fluxes at the 1000 m level ranged from 2 mg C m −2 d −1 in the subtropical ocean to more than 100 mg C m −2 d −1 in the highly productive subpolar sea, and decreased by 25 ± 10% at intervals 1000 m in depth. These results suggest that much particulate matter is transferred rapidly to the bottom of comparatively small areas of the polar, subpolar, hemipelagic and coastal seas and degraded there, and that the bottom water imprint resulting from the effects of degradation of particulate matter is transported fairly quickly to the pelagic ocean by isopycnal mixing and advection. Many unsolved phenomena occurring in the deep ocean can be explained by this suggestion.

The Role of Lubricating Oil in Diesel Particulate and Particulate PAH Emissions

Abstract: The role of lubricating oil in total particulate emissions and in terms of polycyclic aromatic compounds (PAC) associated with the solvent organic fraction (SOF) of the particulate are investigated. Analysis of unused lubricating oil shows negligible concentrations of PAC. Used lubricating oil from a modified Perkins 4.236 Diesel engine, showed significant concentrations of PAC had accumulated in the oil in the form of PAC from unburnt fuel. Analysis of the oil was by gas chromatography using simultaneous parallel triple detection, allowing analysis of polycyclic aromatic hydrocarbons (PAH), nitrogen containing PAH (PANH) and sulphur containing PAH (PASH). Motoring the engine in the absence of fuel enable the contribution of lubricating oil to the exhaust particulate and particulate PAC emission to be determined. At high load and high speed the results indicated that the contribution of lubricating oil to the total exhaust particulate is over 40% and at low load and high speed reaches 70%. Analysis of the solvent organic fraction from the particulates using simultaneous parallel triple detection gas chromatography, revealed the presence of certain PAH which are also present in the lubricating oil. Thus the PAC content of the used oil acts as a source of PAC in particulate PACmore » emissions.« less

Small-scale variability of new production and particulate fluxes in the ocean

Abstract: Particulate carbon losses from the surface waters of the ocean can be estimated from short-term () determinations of the contribution of nitrate to total nitrogen uptake (f(t)), under the assumptio...

Method and apparatus for filtering solid particulate matter from diesel engine exhaust

Abstract: An improved method for removing solid particulate matter from the exhaust of a diesel engine, having the steps of passing the engine's exhaust flow through at least a part of filter means to trap solid particulate matter contained initially in the exhaust, thereby to remove said matter from said exhaust flow, periodically interrupting the exhaust flow through at least said part of the filter means, passing, during said interruption, at least one backflush fluid pulse through at least said part of the filter means thereby to dislodge from the filter means, and entrain, said solid particulate matter, and transporting said dislodged solid particulate matter to the intake of said engine so that said matter can be combusted in the engine, wherein the improvement comprises purge means advantageously positioned so as to allow the discharge of noncombustible particulate matter from the engine before it accumulates to a harmful level.

Direct analysis of diesel particulate-bound hydrocarbons by gas chromatography with solid sample injection

Abstract: Particulate-bound hydrocarbons emitted by diesel engines have been analysed using a rapid new technique. The method involves directly loading filter-borne particulate into a modified injection port of a gas chromatograph. Hydrocarbons are vaporized in this solid sample injection system and subsequently become adsorbed on to a chromatogaphy column. The merits of this procedure are demonstrated by comparing results with those obtained using conventional gas chromatography (with liquid injection) and thermogravimetry. The contribution of unburned engine oil to diesel particulate emissions has been investigated using the new method. For a DI truck diesel engine operated over the U.S. Federal Heavy Duty Transient Cycle it is shown that 40% of the particulate appears to be derived from unburned oil. For a comparable IDI truck diesel engine this value was 28%.

Characterization of mutagenic subfractions of diesel exhaust modified by ceramic particulate traps.

Abstract: Protocols were developed for collection and characterization of heavy-duty diesel exhaust hydrocarbons. Dichloromethane extracts of particulate and gaseous-phase samples were partitioned between hexane and methanol, and the highly mutagenic (Ames TA98) methanolic fractions were further separated with reverse-phase HPLC. Twenty-eight polycyclic aromatic hydrocarbons (PAH), including 4-nitro- and 13 oxy-PAH derivatives, were tentatively identified in the active (moderately polar) HPLC fractions with GC/MS. In terms of raw exhaust emissions (milligrams per cubic meter), the use of the ceramic traps caused reduced levels of particulate and associated organic compounds. Total mutagenic activity also decreased with the traps,but to a lesser extent than the decrease in particulate. Many of the identified PAH were common to both the particulate and gaseous-phase samples collected under the same conditions. Calculated hydrocarbon balances showed that more hydrocarbons passed through the samplers when the ceramic traps were used. 46 references, 5 figures, 5 tables.

Distribution of particulate matter in the Southeastern Beaufort Sea in late summer

Abstract: This paper presents preliminary results describing general features of particulate distributions and dynamics in the open water season

Environmental Impacts of an Old Mine Tailings Deposit — Metal Adsorption by Particulate Matter

Abstract: The distribution of metals (aluminum, manganese, iron, copper, zinc, cadmium and lead) between suspended particles and solution phase has been studied by analysis of time series data in a stream receiving leachates from a mine tailings deposit. A precipitation of aluminum and iron takes place when the acidic effluents are neutralized by unpolluted groundwater, while the other dissolved elements never reach saturation. The particulate fraction is largely amorphous. A transfer of dissolved elements from the solution phase to the particle phase, increasing in the order zinc < cadmium < copper < lead with increasing pH, is observed. This removal of metals from the aqueous phase appears to be due to sorption processes rather than to coprecipitation. The formation of a particulate metal fraction could be the means for long-range transportation and redistribution of metals in environmental water systems.

Characterization of the PAC profile in settling particulates from the urban waters of Stockholm.

Abstract: Polynuclear aromatic compounds (PAC) that enter the aquatic environment either are, or quickly become, adsorbed to particulate matter of anthropogenic and natural origin, and a useful technique for sampling these settling particulates is the use of sediment traps. These vertically-transported particulates which are collected, correspond to the bulk material of the surface bottom sediments. The sampling area in this investigation is located in the waters of central Stockholm. This area is affected by one of the most densely populated urban districts in the Baltic region, inhabited by more than one and a half million people. The total import of petroleum products for consumption to the area in 1985 was 2.5 x 10/sup 6/m/sup 3/. Several power plants and municipal incinerators are situated in the region and several ports and oil terminals are located in the immediate vicinity of the sampling site.

Big Soda Lake (Nevada). 4. Vertical fluxes of particulate matter: Seasonality and variations across the chemocline

Abstract: Vertical fluxes of particulate organic matter were measured with sediment traps above and below the chcmocline of Big Soda Lake to dcfinc the seasonality of sinking losses from the mixolimnion and dctcrmine the effectiveness of the chcmocline (pycnocline) as a barrier to the sinking of biogenic particles. Seasonality of sedimentation rates reflected seasonal changes in the community of autotrophs. During summer-autumn, when production is dominated by autotrophic bacteria, vertical fluxes were small: z 100 mg C m-* d-l and ~0.5 mg Chl a m-* d-r. Following the winter diatom bloom, vertical fluxes increased markedly: ~570 mg C m-* d-l and 23 mg Chl a m-* d-r. The bulk of the seston (> 80%) and particulate carbon (= 65%) sinking to the chemocline passed through it, showing that this very sharp density discontinuity dots not effectively retard the sinking of particulate matter. However sinking losses of particulate carbon were generally small (= 10%) relative to previous measures of primary productivity, indicating that the mixolimnion is a zone of efficient carbon cycling. Exceptions occurred following the winter bloom when sinking losses were a larger fraction (= 40%) of productivity.

The role of suspended matter in the biogeochemical cycles in the Adige River estuary (Northern Adriatic Sea)

Abstract: Suspended matter and sediments from the Adige River mouth were analysed in an attempt to elucidate the transfer of heavy metals from the river to the sea. The vertical profile of grain-size spectra of suspended matter in front of the river mouth has shown that the riverine particles are limited to the upper brackish layer. Particulate matter was found to have a large specific surface area, up to 20 m 2 g −1 in the estuarine sample. High quantities of quartz and phyllosilicates (micas and clay minerals) were found in the riverine suspended matter. The quartz content of the suspended matter from the brackish layer was found to be diminishing and with the organic matter becoming the essential component (22%). Higher levels of trace metals were usually detected in suspended matter samples (40 ppm Ni, 200 ppm Cr, 60 ppm Pb, 100 ppm Cu, 320 ppm Zn, and 0·9 ppm Cd) than in sediments. The observed similarity of physico-chemical, mineralogical and geochemical characteristics of riverine suspended matter and recent marine sediments, indicates that most of the riverborne particulate matter is deposited in the proximity of the Adige River mouth. The peculiar characteristics of the chromium level (high bulk concentration and its abundance in the organic fraction of the particular matter) when compared to the other trace metals, indicates the anthropogenic influence on its biogeocycle.

Wetting of ceramic particulates with liquid aluminum alloys

Abstract: An experimental technique for evaluation of wettability of solid particulates with liquid metal was developed. Uniformly packed powder specimens were prepared with a tamping device specially made for the present experiment, and wetting tests were conducted by pressure infiltration of liquid Al-alloys into the powder specimens. The threshold pressure for infiltration was used as a measure of wettability. With this technique, wettabilities were measured for 10 μm diameter SiC and B4C particulates by several Al-based alloys. Threshold pressures obtained from this technique showed reproducibility to approximately ±7 kPa. Microstructures of infiltrated powder specimens indicated planar front infiltration with no disruption of powder compact during infiltration test and virtually no porosity.

Hydraulic transport of particulate solids

Abstract: (1987). HYDRAULIC TRANSPORT OF PARTICULATE SOLIDS. Chemical Engineering Communications: Vol. 62, No. 1-6, pp. 233-249.