Showing papers on "Particulates published in 1986"

Compositions and fluxes of particulate organic material in the Amazon River1

Abstract: Lignin, elemental, and stable carbon isotope compositions are reported for local plants and for coarse (>63 µm) and fine (<63 µm) suspended particulate materials collected along a 1,950-km reach of the lower Amazon River during four contrasting stages of the 1982–1983 hydrograph. Fluxes of chemically recognizable lignin in the two size classes generally parallel each other along the mainstem with the fine fraction usually predominating. Particulate organic matter transported in the coarse size fraction of the mainstem and its major tributaries is composed of recently formed and well preserved tree leaf debris along with some wood. Organic matter in the fine size fraction is comparatively old, degraded, and rich in immobilized nitrogen and derives primarily from soils. C-4 grasses, which are abundant in the mainstem floodplain (varzea), are not major components of either the coarse or fine particulate material in the river. Particulate organic matter in both size fractions is introduced largely from upstream sources within the Rio Solimoes and Rio Madeira drainage basins. Most of this organic matter is unreactive and is transported conservatively with mineral particles along the Amazon mainstem. However, some downstream compositional trends are seen in both size fractions which reflect the addition or exchange of highly degraded, 13C-depleted, and lignin-poor organic materials from lower basin sources.

Characteristics of atmospheric organic and elemental carbon particle concentrations in Los Angeles

Abstract: A fine particle air monitoring network was operated in the Los Angeles area during 1982. It was found that carbonaceous aerosols accounted for typically 40% of total fine particle mass loadings at most monitoring sites. The ratio of total carbon (TC) to elemental carbon (EC) in ambient samples and in primary source emissions was examined as an indicator of the extent of secondary organic aerosol formation. It was found that TC to EC ratios at all sites on average are no higher than recent estimates of the TC to EC ratio in primary source emissions. There is little evidence of the sustained summer peak in the ratio of TC to EC that one might expect if greatly enhanced secondary organics production occurs during the photochemical smog season. The TC to EC ratio does rise by the time that air masses reach the prevailing downwind edge of the air basin as would be expected if secondary organics are being formed during air parcel transport, but the extent of that increase is modest. These results suggest that primary particulate carbon emissions were the principal contributor to long-term average fine aerosol carbon concentrations in the Los Angeles area during 1982.

A model for Saharan dust transport

Abstract: In this paper the source strength and the deposition rate of the dust emerging from the Sahara are assessed. For this purpose a multichannel sunphotometer has been developed and a turbidity network covering 11 stations has been set up in the Sahara, in the Sahel region and the surrounding southern area for a duration of about two years. A correlation analysis connecting observed aerosol turbidity parameters and mineral dust mass concentration has been performed during a four-week field campaign in Agadez (Niger). An appropriate box model including the aerosol turbidity parameters, actual wind field data of the source regions, the general circulation pattern over Africa and dry and wet deposition reveals a total mass production of about 630 × 106 and 710 × 106 t yr−1 for all suspended particulate matter, 80 × 106 and 90 × 106 t yr−1 for aerosol particles smaller than 5 μm radius for the years 1981 and 1982 respectively. About 60% of the mass moves southward to the Gulf of Guinea, 28% westward to t...

Long‐range transport of continentally‐derived particulate carbon in the marine atmosphere: evidence from stable carbon isotope studies

Abstract: Since 1979, we have investigated marine and non-marine sources of particulate carbon in the marine atmosphere from measurements of carbon concentration and isotopic composition 13 C/ 12 C) Aerosol samples were collected, mostly during the Sea/Air Exchange (SEAREX) Program experiments, in the northern and southern hemispheres (Sargasso Sea, Enewetak Atoll, Peru upwelling, American Samoa, New Zealand, Amsterdam Island) The concentration and the isotopic composition of particulate carbon of marine origin are about the same in both hemispheres (C mean =OO7 μgC m -3 , δ 13 C mean C = -21‰) This component is primarily associated with large sea-salt particles (diameter > 3 μm) Particulate carbon of continental origin displays a variable isotopic composition (δ 13 C range: - 23 to - 28‰,) and is primarily found attached to the smallest aerosol particles (diameter < 1 μm) This continental component shows little temporal variability, but its concentration is much lower in the southern hemisphere (006 μgC m -3 ) than in the northern hemisphere (045 μgC m -3 ) Also, the northern hemisphere samples appear strongly depleted in 13 C compared to those from the southern hemisphere This can be explained on the basis of our isotopic data over various continental areas (Paris region, Ivory Coast, Congo) as due to the predominance in the northern hemisphere of carbonaceous aerosols of anthropogenic origin derived either from industrial combustion processes or from biomass burning On the other hand, our data set from the southern hemisphere appears to reflect primarily natural land-derived biogenic emissions DOI: 101111/j1600-08891986tb00184x

Air pollution and acid rain in China

Abstract: Total annual energy consumption in China has risen by more than 550 million tons coal equivalent in the last thirty years; coal represents the single largest source of energy. Recent surveys have found evidence of coal-related air pollution in the form of airborne particulates and sulfur dioxide. While high levels of suspended particulates and SO/sub 2/ and rain acidity have been identified and though evidence of corrosion and damage to trees and agricultural crops has been gathered, the nature of the relationships between these phenomena has not yet been clearly established. 14 references.

Method of treating fluids

Abstract: A method for treating fluid to remove hydrogen sulfide and sulfur dioxide is disclosed. The method includes passing fluid containing the hydrogen sulfide and/or sulfur dioxide through a bed of metal particulate matter. The metal particulate matter is preferably chosen from metals having favorable redox potentials relative to the redox potentials of these undesirable constituents so as to establish conditions for spontaneous oxidation and reduction reactions between the undesirable constituents and the metal particles.

Detector for particulate density and filter with detector for particulate density

Abstract: A detector for particulate density and the filter for trapping particulates which includes the detector includes a heat resistant insulating member and a pair of electrodes disposed on or within the surface of the filter. When the conductive particulates are attached on the heat resistant insulating member, the resistance of the member is decreased, and reversely, when the particulates are burned away from the member, the resistance is increased. Therefore, by detecting the resistance variation, the particulate density can be measured accurately and the optimum timing to refresh the filter can be determined. The detector is heat resistive, and also can detect whether the filter is completely refreshed or not. The surface of the heat resistant insulating member may be formed to be irregular so that the particulates are easily attached to the member resulting in an increase in measurement precision. An electric heating means for heating particulates trapped on the filter, is mounted in the detector device in order to eliminate hydrocarbon and water content, thereby stabilizing the resistivity of the particulates. Consequently, detecting particulate density can be utilized more precisely. The controller employs a controlling unit for determining the timing to refresh the filter adequately, by receiving the signals of vehicle conditions such as the particulate density.

Particulate fluxes and major components of settling particles from sediment trap experiments in the Pacific Ocean

Abstract: Total particulate fluxes in the deep water column, as measured with sediment traps, were 6–82 mg m−2 day−1 in the subtropical central Pacific of Hawaii and the eastern Pacific off California, 300–420 mg m−2 day−1 in the western Pacific off Japan, and 790–1200 mg m−2 day−1 in the Antarctic Ocean. The fluxes of CaCO3 particles observed at the five stations did not vary widely from station to station. The opal contents, on the other hand, increased with the total particulate fluxes, with the highest observed opal content of the settling particles being 80% in the Antarctic Ocean. Assuming that the clay fraction in the settling particles is refractory, our results show that the regeneration of biogenic particles occurs mainly in the bottom water and at the sediment surface.

Flux of Particulate Matter in the Tidal Marshes and Subtidal Shallows of the Rhode River Estuary

Abstract: There was a net influx of suspended particulate matter to the uppermost part of the Rhode River estuary during the several years of this study. Most of the influx was due to episodic discharges of suspended sediment from the watershed during heavy rains. In contrast, tidal exchange of particulate matter was not related to rainstorms. Sediment composition data and historical records indicate that marsh accretion accounts for only 13% of the sediment trapping although marshes occupy 60% of the study area. Influx of particulate matter to the marshes is directly related to the amount of time they are submerged during tidal cycles.

Surface Water 234Th/238U Disequilibria: Spatial and Temporal Variations of Scavenging Rates within the Pacific Ocean

Abstract: Dissolved and particulate 234Th were determined on several surface transects within the Pacific Ocean. These transects, spanning major oceanographic regimes, ranged from oligotrophic subtropical gyres to eutrophic eastern boundary and equatorial divergence zones. Modeling of the disequilibria between 234Th and 238U within the surface waters provides estimates for the residence time of dissolved thorium with respect to particle scavenging, the residence time of particulate 234Th, and the particulate 234Th flux from the surface layer. The results provide a broad spatial view of the intensity and temporal variability of these scavenging processes. Within the oceanic surface waters dissolved 234Th residence times vary from 6 to 220 days and the scavenging rate of dissolved 234Th onto particles appears to be proportional to primary production. The scavenging intensity of dissolved 234Th is strongly correlated with particulate organic carbon flux throughout a wide range of marine environments ranging from estuaries to the deep sea. Including these environments, which represent end-members for 234Th scavenging intensity, the residence time for dissolved 234Th is shown to vary from 0.3 days to 2 years depending on the particle flux. Particulate 234Th residence times in oceanic surface waters are of the order of weeks and appear to be governed by the rate of zooplankton grazing. Model-derived particulate 234Th fluxes can be used to constrain estimates based upon surface sediment trap collections.

Method and apparatus for trapping and incinerating particulate matter found in diesel engine exhaust

Abstract: A method of removing solid particulate matter from the exhaust of a diesel engine, which comprises 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, interrupting the exhaust flow through at least said part of the filter means, at a time when the preceding period of exhaust flow therethrough is of sufficiently brief duration that the trapped particulate matter has not become resistant to subsequent combustion in the engine, during said interruption backflushing at least said part of the filter means thereby to dislodge from the filter means, and entrain, said solid particulate matter for the purpose of removing it from the filter means, and transporting said dislodged solid particulate matter to the intake of said engine so that said matter can be combusted in the engine; and apparatus for accomplishing same.

Measurements of Sulfur Oxides, Nitrogen Oxides, Haze and Fine Particles at a Rural Site on the Atlantic Coast

Abstract: During August, 1982 and January and February, 1983, General Motors Research Laboratories operated air monitoring sites on the Atlantic Coast near Lewes, Delaware and 1250 km to the east on the southwest coast of Bermuda. The overall purpose of this project was to study the transformations of the principal acid precipitation precursors, NO x and SO x species, as they transport under conditions not complicated by emissions from local sources. In this paper, the measurements of gas and particulate species from Lewes are described and the composition and sources of sulfate aerosol, which is the most important haze-producing species, are investigated. On the average, the total suspended particulate (TSP) concentration was 27.9 μg/m3 while the PM10 (mass of particles with a diameter less than or equal to 10 μm) concentration was 22.0 μg/m3 or 79 percent of the TSP. The PM10 consisted of 6.1 μg/m3 of coarse particles (CPM, diameter = 2.5 − 10μm) and 15.9 μg/m3 of fine particles (FPM, diameter < 2.5 μm). On a mas...

An experimental study of sulfur and NOx fluxes over grassland

Abstract: Three independent sulfur sensors were used in a study of sulfur eddy fluxes to a field of wheat stubble and mixed grasses, conducted in Southern Ohio in September, 1979. Two of these sensors were modified commercial instruments; one operated with a prefilter to measure gaseous sulfur compounds and the other with a denuder system to provide submicron particulate sulfur data. The third sensor was a prototype system, used to measure total sulfur fluxes. The data obtained indicated that the deposition velocity for gaseous sulfur almost always exceeded that for particulate sulfur; average surface conductances were about 1.0 cm s - ' for gaseous sulfur in the daytime and about 0.4 cm s - ' for particulate sulfur. The data indicate that nighttime values were probably much lower. The total sulfur sensor provided support for these conclusions. The boundary-layer quantity ln(z,/z,) was found to be 2.75 f 0.55, in close agreement with expectations and thus providing some assurance that the site was adequate for eddy flux studies. However, fluxes derived using a prototype NO, sensor were widely scattered, partially as a consequence of sensor noise but also possibly because of the effects of nearby sources of natural nitrogen compounds.

The interaction of tidal currents on a disturbed intertidal bottom with a resulting change in particulate matter quantity, texture and food quality

Abstract: The purpose of this investigation was to determine if clam digging had an effect on the suspended sediment texture and composition in the intertidal zone. Surface sediment and suspended particulate samples were collected prior to and after bottom perturbation similar to clam digging. The results indicated that the dug bottom sediments became coarser and contained lower amounts of organic matter. The coarser texture was due to increased winnowing on the ‘rough’ bottom created in the digging process. Suspended sediment concentrations also increased after perturbation, especially over finer-textured areas. The resuspended particulates were well sorted with relatively low organic content. Resuspended bottom sediments contributed virtually no protein to the particulates brought in by the estuarine waters. Recovery rate both of the bottom sediments and the suspended particulates was slow, and seemed dependent on the microtopographic relief which could take weeks to months to return to normal.

Process and system for the oxidation of engine emission particulates deposited in a particulate filter trap

Abstract: A process for the oxidation of a concentration of internal combustion engine emission particulates collected in a particulate filter trap by supplying secondary energy to the deposit at the inlet surface of the filter and/or to the particulate/exhaust gas mixture, includes adjusting the particulate concentration to a value which lies within the explosive range of the particulate/exhaust gas mixture by briefly adding, or recycling, combustible particulates to the exhaust gas flow in the filter, especially in front of the inlet face of the filter.

Control of Atmospheric Fine Primary Carbon Particle Concentrations

Abstract: The adverse health effects and urban visibility degradation associated with atmospheric carbon particle concentrations suggest that control of this class of air pollutants is desirable, especially in the event of an increase in the usage of diesel vehicles. In this study, procedures for the engineering design of fine carbonaceous particulate matter abatement strategies have been developed and tested in the Los Angeles area. Carbon particle abatement strategies are evaluated based on the results of an emissions to air quality model, the performance of which is verified by comparison to measurements of ambient aerosol concentrations taken in the South Coast Air Basin during 1982. As a result of this research, the long-term average behavior of fine aerosol carbon concentrations has been characterized in the Los Angeles area for the first time. The highest concentrations of fine particulate total carbon were observed in areas of heavy traffic density. The annual average fine total carbon concentration at downtown Los Angeles was 12.2 pg m^-3 during 1982, which constituted 37% of the fine aerosol (particle diameter < 2.1 [mu]m) mass collected at that location. Aerosol carbon concentrations were observed to decrease with distance inland from downtown Los Angeles. The 1982 annual average fine total carbon concentration at Rubidoux, which is about 80 km east of Los Angeles. was only 8.2 pg m^-3. There is a pronounced winter peak and summer minimum in carbonaceous aerosol concentrations in the western portion of the air basin. The monthly average fine total carbon concentration at downtown Los Angeles reached a high of 22.3 pg m^-3 during December 1982, and dropped to 7.4 pg m^-3 during June 1982. At eastern locations in the air basin, the seasonal trend becomes less significant, with monthly average fine total carbon concentrations at Rubidoux observed to be between 6.4 and 10.8 pg m^-3 during all months of 1982. Elemental carbon in the atmosphere is inert and is due solely to direct (primary) aerosol emissions from sources while organic carbon could be directly emitted as primary aerosol or could be formed in part from condensation of the low vapor pressure products of atmospheric chemical reactions (secondary formation). Examination of the spatial and temporal trends of the ratio of fine total carbon to fine elemental carbon concentration leads to the conclusion that secondary organic carbon aerosol formed in the atmosphere from hydrocarbon precursors was not the overwhelming contributor to overall long-term average total carbon levels in the Los Angeles area during the year 1982. At downwind locations, such as Azusa or Rubidoux, it was found that, at most, between 16% and 22% of the annual average total carbon concentration (or 27% to 38% of the organic carbon) may be due to secondary aerosol formation in excess of that found at Lennox (a nearcoastal site next to a heavily travelled freeway source of primary aerosol). Comparison of fine elemental and organic carbon particle concentrations against the ratio of those two aerosol species found in basin-wide source emissions farther indicates that, over long averaging times during 1982, primary aerosol carbon particle emissions are responsible for the majority of atmospheric carbon particle concentrations. The particulate air quality data collected during 1982 were used to verify the performance of a mathematical model for long-term average air quality. The Lagrangian particle-in-cell air quality model previously developed by Cass (1977, 1981) was improved to handle near-source dispersion from ground level sources. The model was tested against emissions, elemental carbon air quality, and meteorological data for 1982 in the Los Angeles area. It was found that the model adequately predicts the long-term average concentration of this primary pollutant. The predictions and observations of monthly average elemental carbon particle concentrations have a positive correlation coefficient of 0.78. The model also determines the source classes responsible for fine carbon particle air quality. Many source types: including highway vehicles, charcoal broilers; and fireplaces contribute to primary total carbon particle concentrations, while elemental carbon concentrations are due mostly to emissions from diesel engines. The source class contributions computed by the air quality model were used to determine the optimal emission control strategy for attaining any desired level of improved carbon particle air quality. Linear programming techniques were employed to solve for the least costly set of emission control measures which would enable an air quality goal to be met. Solutions indicate that application of a few control measures, aimed almost entirely at diesel engines, will reduce the basin-wide maximum annual average fine elemental carbon concentration approximately by half at an annual cost of about $69 million. The maximum annual average fine primary particulate total carbon concentration may be reduced by about 55% at a cost of $102 million per year. A control program for visibility improvement would preferentially require the reduction of atmospheric fine elemental carbon particle concentrations, whereas a program designed to control fine aerosol mass would benefit from total carbon particle concentration reductions. It was determined that a control strategy that is optimal for total carbon control may be near-optimal for elemental carbon control. However, an emissions control strategy designed to optimize for elemental carbon control may produce peak total carbon concentrations that exceed those which would result from a control strategy optimized for total carbon by as much as 8%. In summary, it has been demonstrated that the air quality model is useful both in predicting long-term average carbon particle air quality and in determining the sources responsible for that air quality outcome. It was found that emissions from diesel engines were responsible for a large portion of the atmospheric fine carbon particle concentrations in the Los Angeles area during 1982. Control of emissions from diesel engines is therefore important, and it was determined that the least costly set of emission control measures for reducing carbon particle concentrations includes diesel engine emission controls.

An automated method for the analysis of ‘particulate’ carbon and nitrogen in natural waters

Abstract: A method is described for the measurement of the carbon and nitrogen content of particulate material in natural waters. Particulate material is separated by filtration through GF/C filters. The dried filter is encapsulated in silver foil using a purpose made press. Analysis is carried out using high temperature combustion with thermal conductivity detection of emission gasses. Analytical performance characteristics obtained with both standards and natural materials are given.

Seasonal and vertical variations in the elemental composition of suspended and settling particulate matter in Puget Sound, Washington

Abstract: The distributions of C, Al, Si, P, Cr, Mn, Fe, Ni, Cu, Zn and Pb in suspended and settling particulate matter from Puget Sound were studied to investigate the processes affecting the uptake of trace metals by particulate phases. Particulate material was collected by water filtration procedures and sequentially-sampling sediment traps during approximately bimonthly surveys from December 1980 through December 1981 at a station located in the center of the main basin of Puget Sound. The samples were selectively extracted for trace metals associated with oxide, organic, and residual phases and analysed by graphite furnace atomic absorption spectrophotometry and X-ray energy spectrometry. The results show that for Mn, Fe, Zn and Pb, residual and oxide phases were the most important phases controlling the vertical flux; whereas residual and organic phases controlled the vertical flux of Cu. The average annual flux data were used along with dissolved metal profiles to compute scavenging residence times for several trace metals in Puget Sound. Relatively short scavenging residence times (i.e. 100 days) were calculated for metals enriched in organic phases, such as Cu.

Settling Flux and Sinking Velocities of Particulate Phosphorus (PP) and Particulate Organic Carbon (POC) in Lake Zug, Switzerland

Abstract: Model predictions about the restoration of Lake Zug require the use of terms to express removal of particulate phosphorus (PP) to the sediment. Sediment traps were used to measure sedimentation rates, and particulate concentrations were measured in the overlying water column. Mean sinking velocities were used in a dynamic model of the lake, instead of the net P sedimentation. Differences between calculated and predicted sinking velocities may be balanced by using a lake-specific constant. The constant varies seasonally, locally, and with depth/time of settlement, as the size and composition of particles change.