Fine Particulate Organic Material Research Articles

Evaluation of Fish Farm Effluent Contamination Using Bio-Indicators Based on Macroinvertebrate Communities

The progress of the aquaculture industry in Iran as an environmental and economical maintainable process needs an efficient and low-cost tool for regular checking of adjacent environments. Biological monitoring by macroinvertebrate is operative for assessment of water quality. Sampling operation was carried out to investigate the influence of aquaculture wastewater on macroinvertebrate communities at 4 stations over one year (spring, summer, autum and winter) in the Chehel Chai River. 2040 (19% spring, 18% summer, 25% autumn and 38% winter) macroinvertebrate specimens belonging to 6 orders and 14 families were recognized. The most abundance among the stations belonged to the Diptera and Chironomidae. Two groups of macroinvertebrate assemblages (sensitive to tolerance) and three groups of stations (upstream, outfall and down1 and down2) were identified with Heat map analysis. The study was showed that rainbow trout farm most often significantly increase in the influence of fine particulate organic material (FPOM %), NO3 and PO4. According to HFBI results, organic water pollution at different stations was classified as good (upstream), appropriate, relatively poor and poor (outfall). The combined results of the biomarkers were showed that the outfall station had more organic contamination than its predecessor station (relatively poor water quality) which required more efficient management based on the self-purification capacity of the Chehel Chai River.

Macroinvertebrados acuáticos de la quebrada Los Alisos, Firavitoba - Boyacá

Se presenta la composición y algunas implicaciones funcionales de los macroinvertebrados acuáticos existentes en la cabecera de la quebrada Los Alisos, ubicada al occidente del municipio de Firavitoba en el departamento de Boyacá. Se realizaron dos muestreos durante los meses de agosto y septiembre de 2016. Se determinaron los grupos funcionales alimenticios y algunos rasgos biológicos a partir información bibliográfica, se encontraron siete mecanismos de alimentación y 19 rasgos biológicos. Se recolectaron 2688 individuos pertenecientes a tres filos, seis clases, 11 órdenes 21 familias y 14 géneros, en donde la mayor abundancia relativa correspondió al género Hyalella (Amphipoda, 20,3 %). El grupo trófico de los detritívoros-colectores o consumidores de depósito (C2), fue el más frecuente en el sistema (68,2 %), el cual sugiere que predomina la materia orgánica particulada fina (MOPF). La respiración branquial es la forma de más frecuente ya que se presenta en 12 de los 22 grupos taxonómicos con el 54,5 %. La mayoría de los organismos (54,5 %) presentan ganchos tarsales (GT), que pueden ser usados eventualmente como una forma de resistencia al contraflujo. Casi todos los organismos estudiados caminan o se arrastran (AR, 68,2 %), utilizando variedad de hábitats como sustratos. La flexibilidad de las historias de vida y movilidad que muestran las características de los grupos taxonómicos encontrados en la quebrada Los Alisos pueden influenciar la forma como obtienen su alimento.

Broadening the Regulated‐River Management Paradigm: A Case Study of the Forgotten Dead Zone Hindering Pallid Sturgeon Recovery

The global proliferation of dams within the last half century has prompted ecologists to understand the effects of regulated rivers on large‐river fishes. Currently, much of the effort to mitigate the influence of dams on large‐river fishes has been focused on downriver effects, and little attention has been given to upriver effects. Through a combination of field observations and laboratory experiments, we tested the hypothesis that abiotic conditions upriver of the dam are the mechanism for the lack of recruitment in Pallid Sturgeon (Scaphirhynchus albus), an iconic large‐river endangered species. Here we show for the first time that anoxic upriver habitat in reservoirs (i.e., the transition zone between the river and reservoir) is responsible for the lack of recruitment in Pallid Sturgeon. The anoxic condition in the transition zone is a function of reduced river velocities and the concentration of fine particulate organic material with high microbial respiration. As predicted, the river upstream of the transition zone was oxic at all sampling locations. Our results indicate that transition zones are an ecological sink for Pallid Sturgeon. We argue that ecologists, engineers, and policy makers need to broaden the regulated‐river paradigm to consider upriver and downriver effects of dams equally to comprehensively mitigate altered ecosystems for the benefit of large‐river fishes, especially for the Pallid Sturgeon.

Modifications to the Sunset Laboratory Carbon Aerosol Monitor for the Simultaneous Measurement of PM2.5 Nonvolatile and Semi-Volatile Carbonaceous Material

Semi-volatile organic carbonaceous material (SVOC) in fine particles is not reliably measured with conventional semicontinuous carbon monitors because semi-volatile carbonaceous material is lost from the collection media during sample collection. Two modifications of a Sunset Laboratory carbon aerosol monitor allowing for the determination of semi-volatile fine particulate organic material are described. Collocated conventional and modified instruments were operated simultaneously using a common inlet. Comparisons were made with integrated PC-BOSS data for quartz filter retained nonvolatile organic carbon (NVOC) and elemental carbon (EC), SVOC, and total carbon (TC = SVOC + NVOC + EC) and good agreement was observed between TC concentrations during studies conducted in Rubidoux, CA. Precision of the comparison was σ=±1.5 μg-C/m3 (±8%). On the basis of experiments performed with the modified Sunset monitor, a dual-oven Sunset monitor was developed and extensively tested in Lindon, UT; Riverside, CA; and in environmental exposure chambers. The precision for the measurement of TC with the dual-oven instrument was σ = ±1.4 μg-C/m3 (±13%).

Comparison of Speciation Sampler and PC-BOSS Fine Particulate Matter Organic Material Results Obtained in Lindon, Utah, during Winter 2001–2002

The Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) has been previously verified as being capable of measuring total fine particulate matter (PM2.5), including semi-volatile species. The present study was conducted to determine if the simple modification of a commercial speciation sampler with a charcoal denuder followed by a filter pack containing a quartz filter and a charcoal-impregnated glass (CIG) fiber filter would allow for the measurement of total PM2.5, including semi-volatile organic material. Data were collected using an R&P (Rupprecht and Pastasnik Co., Inc.) Partisol Model 2300 speciation sampler; an R&P Partisol speciation sampler modified with a BOSS denuder, followed by a filter pack with a quartz and a CIG filter; a Met One spiral aerosol speciation sampler (SASS); and the PC-BOSS from November 2001 to March 2002 at a U.S. Environmental Protection Agency (EPA) Science to Achieve Results (STAR) sampling site in Lindon, UT. Total PM2.5 mass, ammonium nitrate (both nonvolatile and semi-volatile), ammonium sulfate, organic carbon (both non-volatile and semi-volatile), and elemental carbon were determined on a 24-hr basis. Results obtained with the individual samplers were compared to determine the capability of the modified R&P speciation sampler for measuring total PM2.5, including semi-volatile components. Data obtained with the modified speciation sampler agreed with the PC-BOSS results. Data obtained with the two unmodified speciation samplers were low by an average of 26% because of the loss of semi-volatile organic material from the quartz filter during sample collection.

Fine Particulate Chemical Composition and Light Extinction at Meadview, AZ

The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr day-night samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was ±0.6 μg/m3 organic material, ±0.3 μg/m3 ammonium sulfate, and ±0.07 μg/m3 ammonium nitrate. Data were also available on fine particulate crustal material, fine and coarse particulate mass from the Interagency Monitoring of Protected Visual Environments sampling system, and relative humidity (RH), light absorption, particle scattering, and light extinction measurements from Project MOHAVE. An extinction budget was obtained using mass scattering coefficients estimated from particle size distribution data. Literature data were used to estimate the change in the mass scattering coefficients for the measured species as a function of RH and for the absorption of light by elemental carbon. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. During periods of highest light extinction, contributions from fine particulate organic material, sulfate, and light-absorbing carbon dominated the extinction of light by particles. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction.

Flood-borne sediment analysis of the Hoanib River, northwestern Namibia

The suspended sediment contained in six flood events in the Hoanib River catchment during the wet season of 1999/2000 were analysed for volatile (or low molecular weight) fine particulate organic material (FPOM), higher molecular weight FPOM and the total organic carbon (TOC). Samples were evaporated to dryness at 80 °C, then heated in a high temperature oven to 250, 550 and 850 °C. The results show that the amount of sediment carried during the flood events varied between 1.54 and 31.27 g/L, with an average of 14.62 g/L. The amount of suspended sediment in the flood-waters (2.789–616.359×10 6 kg) was found to be dependent on the timing and duration of the flood event. The largest percentage of organic material was found in the volatile FPOM fraction (5.77±6.26%), with lesser amounts being found in the higher molecular weight FPOM (3.36±0.62%) and TOC (4.93±1.86%) fractions.

Macroinvertebrate community responses to selection logging in riparian and upland areas of headwater catchments in a northern hardwood forest

Aquatic insect communities were examined in 2 streams at different selection logging intensities in headwater catchments of a northern hardwood forest. Insect communities of these streams were compared to those of a nearby reference stream (no harvesting) over a 2-y pre- and 3- y post-logging period. The experimental catchments were logged by a mechanical harvester and cable skidders, one at a low-intensity (29% basal area removal) and the other at a moderate-intensity (42% basal area removal) harvesting rate. There were no riparian reserves or buffer zones, but logging was conducted in compliance with a riparian code of practice (3-m setback from stream edges) and other best management practices. Changes in community structure, community metrics, or relative abun- dance of discriminatory taxa attributable to logging impacts were not detected at the low-intensity site. Some deviations from reference and pre-logging trends in community structure, multivariate dispersion, and population levels of discriminatory taxa were detected at the moderate-intensity site after the logging. These deviations were mainly driven by small, but usually significant, increases in abundance of 5 gatherer taxa. The increases in abundance of gatherer taxa appeared to be a response to a significant increase (;2.53) in streambed deposition of fine particulate organic material at that site. However, the shifts in community structure and changes in abundance of these taxa at the moderate-intensity site were not larger than some natural changes in abundance among other taxa at the reference site over the 5-y study. The increases in abundance of some taxa at the moderate- intensity site may indicate a logging impact, but the changes were small and there were no indications of reciprocal declines among other taxa. It appears that selection logging at up to 42% basal area removal in compliance with the riparian code of practice and other good management practices largely mitigated harmful alterations to stream habitat and insect communities in these northern hardwood forest catchments.

Trophic position and potential food sources of 2 species of unionid bivalves (Mollusca:Unionidae) in 2 small Ohio streams

We determined the trophic positions of 2 species of freshwater mussels, Elliptio dilatata and Ptychobranchus fasciolaris, from 2 small streams in central Ohio by measuring stable C and N isotope ratios and digestive fluid enzyme activities. We also examined stable C and N isotopes, microbial biomass, microbial community structure, nutrient (i.e., C, N, and P) concentrations, and contribution of microbial C to total fine particulate organic C (FPOC). We hypothesized that 1) allochthonous inputs compose most of FPOC, 2) mussels use fine particulate organic material (FPOM) as a food source, and 3) mussels respond to the low-protein content of FPOM by showing high protease activity. Microbial C composed 35 to 86% of total FPOC during the autumn sampling period. FPOM stable isotope values varied seasonally, whereas δ13C and δ15N content in mussel tissue was spatially (i.e., among sites) and temporally similar. Mussels were 2 to 4‰ more depleted in δ13C than seasonal FPOM. Digestive fluid enzymes were spatially and temporally stable across species, with activity of esterase > protease > lipase > glucosidase. Lipase:protease of digestive fluids from mussels were <1, indicating a low-protein diet. Our results suggest that microbial biomass in FPOM constitutes a large portion of mussel diet and that mussels assimilate significant amounts of C from this source.

Trends in PM 2.5 composition at the Department of Energy OST NETL fine particle characterization site in Pittsburgh, PA, USA

This paper reports on the results from the first 6 months (from November 1999 to April 2000) of an ongoing monitoring study of fine particulate air pollutants at the Department of Energy's Office of Science and Technology (OST) NETL sampling site, 30 km southwest of Pittsburgh city center, Pennsylvania. This study is part of a 2-year sampling program for PM characterization, under the auspices of The University Coal Research Program of the National Energy Technology Laboratory (NETL), US Department of Energy in Pittsburgh, PA, USA. Samples were collected daily with a Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) to determine PM 2.3 composition, including the semi-volatile organic compounds (SVOC) and ammonium nitrate lost from particles during sampling. Average fine particulate composition during the 6-month period was: constructed PM 2.3, 19.4 μg m −3; ammonium sulfate 4.3 μg m −3; non-volatile organic material, 6.9 μg m −3; elemental carbon, 0.4 μg m −3; SVOC lost from particles during sampling, 6.1 μg m −3; retained ammonium nitrate, 1.4 μg m −3; lost ammonium nitrate, 0.3 μg m −3. Results from the PC-BOSS sampler are also compared with those obtained from a Federal Reference Method PM 2.5 sampler, and a Tapered Element Oscillating Microbalance monitor, both of which tended to not measure the semi-volatile particulate matter. SVOC concentrations were highest in the spring. Episodes of fine particulate non-volatile organic material occurred throughout the 6-month period. Average ammonium sulfate concentrations were higher in November and January than the other months for the study period.

Semi-volatile secondary organic aerosol in urban atmospheres: meeting a measurement challenge

Ammonium nitrate and semi-volatile organic compounds are significant components of fine particles in urban atmospheres. These components, however, are not properly determined with current US EPA accepted methods such as the PM 2.5 FRM or other single filter samplers due to significant losses of semi-volatile material (SVM) from particles collected on the filter during sampling. Continuous PM 2.5 mass measurements are attempted using methods such as the R&P TEOM monitor. This method, however, heats the sample to remove particle-bound water which also results in evaporation of SVM. Research at Brigham Young University has resulted in samplers for both the integrated and continuous measurement of total PM 2.5, including the SVM. The PC-BOSS is a charcoal diffusion denuder based sampler for the determination of fine particulate chemical composition including the semi-volatile organic material. The RAMS is a modified TEOM monitor which includes diffusion denuders and Nafion dryers to remove gas phase material which can be absorbed by a charcoal sorbent filter. The RAMS then uses a “sandwich filter” consisting of a conventional particle collecting Teflon coated TX40 filter, followed by an activated charcoal sorbent filter which retains any semi-volatile ammonium nitrate or organic material lost from the particles collected on the TEOM monitor Teflon coated filter, thus allowing for determination of total PM 2.5 mass including the SVM. Recent research conducted by Brigham Young University using these two samplers has indicated the following about semi-volatile organic aerosol: • The majority of semi-volatile fine particulate organic material is secondary organic aerosol. • This semi-volatile organic aerosol is not retained on the heated filter of a regular TEOM monitor and hence is not measured by this sampling technique. In addition, secondary ammonium nitrate is also lost. • Much of the semi-volatile organic aerosol is also lost during sampling from single filter samplers such as the PM 2.5 FRM sampler. • The amount of semi-volatile organic aerosol lost from single filter samplers can vary from less than 1 3 that lost from heated TEOM filters during cold winter conditions to essentially all during warm summer conditions. • Semi-volatile organic aerosol can only be reliably collected using an appropriate denuder sampler. • Either a PM 2.5 FRM sampler or the IMPROVE sampler can be easily modified to a denuder sampler with filters which can be analyzed for semi-volatile OC, nonvolatile OC and EC using existing OC/EC analytical techniques. The research upon which these statements are based is summarized in this document.

The influence of temperature and food on size and weight of adult Chaetopteryx villosa (Fabricius) (Insecta: Trichoptera) along a stream gradient

Adults of Chaetopteryx villosa (FABRICIUS) (Trichoptera, Limnephilidae) show marked differences in size and weight between sexes at individual stream sites. Size and weight of females increase with distance from the source of the Breitenbach. By rearing specimens from individual egg masses, differences between sexes were attributed to distinct life histories. Males remained longer in larval instars I to III; females spent a greater proportion of the life cycle in instars IV and V. As a result, females were almost twice the size of males. An in-stream enclosure experiment demonstrated that sex, food quality (fine or coarse particulate organic material; FPOM, CPOM), water temperature and, to a smaller extent, origin of specimens determined the size and weight of the developing adults. However, the percent fat content of males and females was unaffected by these factors. Because FPOM and CPOM in the stream were not limiting, size of the adults was determined predominantly by water temperature. Results of the in-stream experiment agreed well with the size and weight patterns observed over a ten-year period in the stream under investigation (Breitenbach). The amount of nutrients invested in the growth of two males was almost identical to that invested in the growth of one female. Maximum size and weight of C. villosa females occurred at sites with the lowest population densities. This pattern reflected the accumulation of degree days rather than a limitation by increased competition for food.

High-Volume Diffusion Denuder Sampler for the Routine Monitoring of Fine Particulate Matter: II. Field Evaluation of the PC-BOSS

The high-volume Brigham Young University organic sampling system with a particle concentrator (PC-BOSS) has been field evaluated for the determination of airborne fine particulate matter including semivolatile chemical species during 3 intensive sampling programs in 1997: Tennessee Valley Authority (TVA), Lawrence County, TN; Riverside, CA; and Provo, UT. The PC-BOSS precision was tested using 2 collocated PC-BOSS samplers. In addition, the PC-BOSS results were compared with results from a prototype PM 2.5 U.S. EPA federal reference method (FRM sampler), a filter pack sampler (quartz and charcoal sorbent filters), the BIG BOSS, an annular denuder sampler, and the ChemSpec sampler for the determination of major fine particulate species. Fine particulate mass, sulfate, nitrate, and organic carbonaceous material (OC) determined by 2 PC-BOSS samplers agreed within - 10%. Possibly due to absorption of SO 2 by a quartz filter, the sulfate concentrations determined by the filter pack sampler and the BIG BOSS wer...

Effect of Semivolatile Material on PM 2.5 Measurement by the PM 2.5 Federal Reference Method Sampler at Bakersfield, California

The chemical composition of fine particulate material was determined for samples collected in Bakersfield, CA, during February-March, 1998 using several diffusion denuder samplers, including the PC-BOSS, which measures both semivolatile fine particulate nitrate and organic material. An average of 56% of the fine particulate carbonaceous material was lost from the filters of the Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS). A comparable amount of fine particulate semivolatile organic material was also lost from collected particles with single filter samplers, such as the PM 2.5 Federal Reference Method. The fraction of nitrate lost from collected particles was a function of temperature and humidity, with the biggest effect being due to temperature. The fraction of nitrate lost was comparable for conventional annular denuder samplers and the PM 2.5 FRM, averaging 33%. The nitrate loss from particles for the PC-BOSS was smaller, averaging 11%, possibly due to the concentration of particulate material prior to collection with this sampler. The loss of nitrate and semivolatile organic material during sample collection resulted in the PM 2.5 FRM sampler giving PM 2.5 mass that was an average of 30% (7.3 w g/m 3 ) lower than the true value and different from the true value from negligible to 20 w g/m 3 .

Composition of particulate and dissolved organic matter in a disturbed watershed of southeast Brazil (Piracicaba River basin)

The elemental and isotopic composition of particulate and dissolved organic matter was investigated in the Piracicaba River basin, São Paulo State, Brazil. Comparison of riverine organic matter from the Piracicaba River basin, a region where rivers and streams receive urban sewage and industrial effluents, with data reported for the pristine Amazon system revealed significant differences associated with anthropogenic impacts. One important difference was N enrichment in the particulate organic material of the Piracicaba basin rivers, due to (a) urban and industrial effluents, and (b) enhanced phytoplankton growth, which results from the combination of nutrient enrichment and damming of sections of the rivers. Radiocarbon concentrations were overall more depleted (older 14C age) in the Piracicaba basin rivers than in the Amazon, which may reflect the importance of soil erosion in the former. Analyses of stable and radioactive carbon isotopes and lignin-derived compounds indicated that coarse particulate organic material is composed of a mixture of soil particles and degraded organic matter from C3 and C4 vascular plants. Fine particulate organic material was composed mainly of soil particles and phytoplankton cell remains, the latter especially during low water. Ultrafiltered dissolved organic matter was the most degraded fraction according to its lignin oxidation products, and showed the greatest influence of C4 plant sources.

Determination of Fine Particulate Semi-Volatile Organic Material at Three Eastern U.S. Sampling Sites

ABSTRACT Correct assessment of fine particulate carbonaceous material as a function of particle size is, in part, dependent on the determination of semi-volatile compounds, which can be lost from particles during sampling. This study gives results obtained for the collection of fine particulate carbonaceous material at three eastern U.S. sampling sites [Philadelphia, PA; Shenandoah National Park, VA; and Research Triangle Park (RTP), NC] using diffusion denuder technology. The diffusion denuder samplers allow for the determination of fine particulate organic material with no artifacts, due to the loss of semi-volatile organic particulate compounds, or collection of gas-phase organic compounds by the quartz filter during sampling. The results show that an average of 41, 43, and 59% of fine particulate organic material was lost as volatilized semi-volatile organic material during collection of particles on a filter at Philadelphia, RTP, and Shenandoah, respectively. The particle size distribution of carbonaceous material retained by a filter and lost from a filter during sampling was obtained for the samples collected at Philadelphia and Shenandoah. The carbonaceous material retained by the particles during sampling was found predominantly in particles smaller than 0.4 μm in aerodynamic diameter. In contrast, the semi-volatile organic material lost from the particles during sampling had a mass median diameter of ~0.5 μm.

Impacts of an inter-basin water transfer: distribution and abundance ofMicronecta poweri (Insecta: Corixidae) in the River Wear, north-east England

1. Micronecta poweri (Insecta: Corixidae) is potentially sensitive to changes in river flow. A field experiment was designed to assess the impact of an inter-basin water transfer on the distribution and abundance of M. poweri in the receiving River Wear, north-east England. 2. The transfer increased river discharge threefold for a period of 1 h; the transfer discharge was then reduced to a rate equivalent to double the receiving flow. Velocity changes were variable: some parts of the river channel were subjected to order of magnitude increases in near-bed velocity, others suffered no perceptible change. Losses of fine particulate organic material were associated with the areas of greatest velocity increase. 3. Downstream of the transfer outlet, average total M. poweri abundance in replicate samples was reduced by approximately 50% during the transfer. Losses were variable within the 250 m reach monitored, with some areas gaining and some losing animals. Differences could not be explained simply as a function of proximity to the transfer outlet. 4. Results suggest that transfer impacts are location specific, varying greatly even over short (250 m) distances. For flow sensitive taxa, even relatively minor flow changes (increasing discharge to the 50 percentile flow value) may be considered as disturbance events when viewed at the patch or reach scales. 5. Despite the impacts identified for M. poweri, transfers are generally viewed as having a beneficial effect on the conservation of aquatic habitat in the River Wear. They ensure that water abstractions for potable and industrial supply can continue during the summer months without reducing the availability of suitable salmonid habitat. However, there remains a need to assess the possible transfer of biological material from the donor River Tyne to the receiving River Wear. Copyright © 2000 John Wiley & Sons, Ltd.

LINKING SPECIES AND ECOSYSTEMS: DIFFERENT BIOTIC ASSEMBLAGES CAUSE INTERSTREAM DIFFERENCES IN ORGANIC MATTER

Here we test the hypothesis that differences in macrobiotic assemblages can lead to differences in the quantity and quality of organic matter in benthic depositional environments among streams in montane Puerto Rico. We experimentally manipulated biota over a 30–40 d period in two streams with distinctly different macrobiotic assemblages: one characterized by high densities of omnivorous shrimps (Decapoda: Atyidae and Xiphocarididae) and no predaceous fishes, and one characterized by low densities of shrimps and the presence of predaceous fishes. To incorporate the natural hydrologic regime and to avoid confounding artifacts associated with cage enclosures/exclosures (e.g., high sedimentation), we used electricity as a mechanism for experimental exclusion, in situ. In each stream, shrimps and/or fishes were excluded from specific areas of rock substrata in four pools using electric “fences” attached to solar-powered fence chargers. In the stream lacking predaceous fishes (Sonadora), the unelectrified control treatment was almost exclusively dominated by high densities of omnivorous shrimps that constantly ingested fine particulate material from rock surfaces. Consequently, the control had significantly lower levels of inorganic sediments, organic material, carbon, and nitrogen than the exclusion treatment, as well as less variability in these parameters. Tenfold more organic material (as ash-free dry mass, AFDM) and fivefold more nitrogen accrued in shrimp exclosures (10.6 g AFDM/m2, 0.2 g N/m2) than in controls (1.1 g AFDM/m2, 0.04 g N/m2). By reducing the quantity of fine particulate organic material and associated nitrogen in benthic environments, omnivorous shrimps potentially affect the supply of this important resource to other trophic levels. The small amount of fine particulate organic matter (FPOM) that remained in control treatments (composed of sparse algal cells) was of higher quality than that in shrimp exclosures. This is evidenced by the significantly lower carbon-to-nitrogen (C/N) ratio (an indicator of food quality, with relatively low C/N indicating higher food quality) in the control relative to the shrimp exclosure treatment. In contrast, the stream with predaceous fishes (Bisley) was characterized by very low numbers of shrimps, and macrobiota had no significant effect on benthic sediments, organic matter, C, N, and C/N. All parameters were highly variable through time, with levels and ranges in variability similar to the shrimp exclusion treatment in the Sonadora. Our experimental results are consistent with findings of an independent survey of six streams in four different drainages. Four streams that had an abundance of omnivorous shrimps, but lacked predaceous fishes, had extremely low levels of fine benthic organic and inorganic material. In contrast, two streams that had low densities of shrimps and contained predaceous fishes had significantly higher levels. Results show a strong linkage between species and ecosystem characteristics: interstream differences in the quantity and quality of fine benthic organic matter resources were determined by the nature of the macrobiotic assemblage. Furthermore, patterns in the distribution of shrimp assemblages reflected landscape patterns in the benthic depositional environment among streams.

Particulate organic compounds emitted from motor vehicle exhaust and in the urban atmosphere

The emission rate of particle-phase petroleum biomarkers in vehicular exhaust compared to the concentrations of these biomarkers in ambient air is used to determine the particulate organic compound concentration due to primary particle emissions from motor vehicles in the southern California atmosphere. A material balance on the organic particulate matter emitted from motor vehicle traffic in a Los Angeles highway tunnel first is constructed to show the proportion which is solvent-extractable and which will elute from a GC column, the ratio of resolved to unresolved compound mass, the portion of the resolved material that can be identified as single organic compounds, and the contribution of different classes of organic compounds to the overall identified fraction. It is shown that the outdoor ambient concentrations of the petroleum biomarkers track primary emissions measured in the highway tunnel, confirming that direct emissions of these compounds from vehicles govern the observed ambient petroleum biomarker concentrations. Using organic chemical tracer techniques, the portion of fine organic particulate matter in the Los Angeles atmosphere which is attributable to direct particle emissions from vehicle exhaust is calculated to vary from 7.5 to 18.3% at different sites throughout the air basin during a summertime severe photochemical smog episode. A similar level of variation in the contribution of primary motor vehicle exhaust to fine particulate organic matter concentrations during different times of day is seen. While peak atmospheric concentrations of fine particulate organic carbon are observed during the 1200–1600 PDT afternoon sampling period, only 6.3% of that material is apportioned to the directly emitted particles from vehicle exhaust. During the morning traffic peak between 0600–1000 PDT, 19.1% of the fine particulate organic material is traced to primary emissions from motor vehicles.

Fine Particulate Organic Material in the Los Angeles Basin - I: Assessment of the High-Volume Brigham Young University Organic Sampling System, BIG BOSS

ABSTRACT A multi-system, high-volume, parallel plate diffusion dénuder Brigham Young University Organic Sampling System (BIG BOSS) was tested using collocated samplers at the Pico Rivera Monitoring Station of the South Coast Air Quality Management District, South Coast Air Basin, in September 1994. Six-hr daytime and 9-hr nighttime samples were collected with a flow of about 200 L/min through each of the three systems designed to collect particles smaller than 2.5, 0.8, and 0.4 mm in a diffusion denuder sampler. Efficiency for the removal of gas phase organic compounds by the diffusion denuder was evaluated using both theoretical predictions and field measurements. Both measured and calculated data indicate high denuder efficiency for the removal of gas phase aromatic and paraffinic compounds. The precision of the BIG BOSS was evaluated using collocated samplers. The precision of determination of total carbon and elemental carbon retained by a quartz filter or of semi-volatile carbonaceous material lost from particles during sampling averaged ±7%. The precision of determination of individual organic compounds averaged ±10%. An average of 42 and 62% of the particulate organic material was semi-volatile organic compounds (SVOCs) lost from particles during sampling for daytime and nighttime samples, respectively. This “negative” sampling artifact was an order of magnitude larger than the “positive” quartz filter artifact due to adsorption of gas phase organic material. Daytime concentrations of fine particulate elemental carbon and nonvolatile organic carbon were higher than nighttime concentrations, but nighttime fine particles contained more semi-volatile organic material than daytime.