Macrofauna diversity in<Emphasis Type="Italic"> Posidonia oceanica</Emphasis> detritus: distribution and diversity of mobile macrofauna in shallow sublittoral accumulations of<Emphasis Type="Italic"> Posidonia oceanica</Emphasis> detritus

The mobile macrofauna in submerged detritus accumulations (SDAs) of the seagrass Posidonia oceanica was investigated in the Bay of Calvi, Corsica, Mediterranean Sea. The distribution of the macrofauna was related to the exposure of the habitat and to the degree of packing and decomposition of the SDAs. In the less decomposed, younger SDAs, the number of individuals per species, but also species richness, was relatively low. In the more decomposed, older SDAs, the abundance and number of species increased, showing predominance of a few crustacean taxa such as gammaridean amphipods, shrimps and the leptostracan Nebalia bipes. Many of the macrofaunal species in the SDAs are members of the animal communities of surrounding seagrass meadows or adjacent hard or soft bottoms, while others, like N. bipes, apparently live in closer association with the SDAs.Communicated by O. Kinne, Oldendorf/Luhe     

Methane oxidation in a landfill cover with capillary barrier

The methane oxidation potential of a landfill cover with capillary barrier was investigated in an experimental plant (4.8 m x 0.8 m x 2.1m). The cover soil consisted of two layers, a mixture of compost plus sand (0.3 m) over a layer of loamy sand (0.9 m). Four different climatic conditions (summer, winter, spring and fall) were simulated. In and outgoing fluxes were measured. Gas composition, temperature, humidity, matrix potential and gas pressure were monitored in two profiles. CH4 oxidation rate within the investigated top cover ranged from 98% to 57%. The minimum was observed for a short time after irrigation. Temperature distribution, gas concentration profiles and lab-scaled batch experiments indicate that before irrigation the highest oxidising activity took place in a depth of about 30 cm. After irrigation the oxidising horizon seemed to migrate upwards since methanotrophic bacteria develop better there due to an adequate supply with oxygen. It can be assumed that the absence of oxygen is one of the most important limiting factors for the CH4 oxidation process. Abrupt cross-overs between horizons of different soil material may lead to zones of increased water saturation and decreased soil respiration.     

Predicting particulate (PM10) personal exposure distributions using a random component superposition statistical model

This paper presents a new statistical model designed to extend our understanding from prior personal exposure field measurements of urban populations to other cities where ambient monitoring data, but no personal exposure measurements, exist. The model partitions personal exposure into two distinct components: ambient concentration and nonambient concentration. It is assumed the ambient and nonambient concentration components are uncorrelated and add together; therefore, the model is called a random component superposition (RCS) model. The 24-hr ambient outdoor concentration is multiplied by a dimensionless "attenuation factor" between 0 and 1 to account for deposition of particles as the ambient air infiltrates indoors. The RCS model is applied to field PM10 measurement data from three large-scale personal exposure field studies: THEES (Total Human Environmental Exposure Study) in Phillipsburg, NJ; PTEAM (Particle Total Exposure Assessment Methodology) in Riverside, CA; and the Ethyl Corporation study in Toronto, Canada. Because indoor sources and activities (smoking, cooking, cleaning, the personal cloud, etc.) may be similar in similar populations, it was hypothesized that the statistical distribution of nonambient personal exposure is invariant across cities. Using a fixed 24-hr attenuation factor as a first approximation derived from regression analysis for the respondents, the distributions of nonambient PM10 personal exposures were obtained for each city. Although the mean ambient PM10 concentrations in the three cities varied from 27.9 micrograms/m3 in Toronto to 60.9 micrograms/m3 in Phillipsburg to 94.1 micrograms/m3 in Riverside, the mean nonambient components of personal exposures were found to be closer: 52.6 micrograms/m3 in Toronto; 52.4 micrograms/m3 in Phillipsburg; and 59.2 micrograms/m3 in Riverside. The three frequency distributions of the nonambient components of exposure also were similar in shape, giving support to the hypothesis that nonambient concentrations are similar across different cities and populations. These results indicate that, if the ambient concentrations were completely controlled and set to zero in all three cities, the median of the remaining personal exposures to PM10 would range from 32.0 micrograms/m3 (Toronto) to 34.4 micrograms/m3 (Phillipsburg) to 48.8 micrograms/m3 (Riverside). The highest-exposed 30% of the population in the three cities would still be exposed to 24-hr average PM10 concentrations of 47-74 micrograms/m3; the highest 20% would be exposed to concentrations of 56-92 micrograms/m3; the highest 10% to concentrations of 88-131 micrograms/m3; and the highest 5% to 133-175 micrograms/m3, due only to indoor sources and activities. The distribution for the difference between personal exposures and indoor concentrations, or the "personal cloud," also was similar in the three cities, with a mean of 30-35 micrograms/m3, suggesting that the personal cloud accounts for more than half of the nonambient component of PM10 personal exposure in the three cities. Using only the ambient measurements in Toronto, the nonambient data from THEES in Phillipsburg was used to predict the entire personal exposure distribution in Toronto. The PM10 exposure distribution predicted by the model showed reasonable agreement with the PM10 personal exposure distribution measured in Toronto. These initial results suggest that the RCS model may be a powerful tool for predicting personal exposure distributions and statistics in other cities where only ambient particle data are available.     

Bioaccumulation of Toxic Organic Compounds and Their Isomers into the Organism of Seals in West-Estonian Archipelago Biosphere Reserve

The Estonian coastal waters serve as the south-eastern boundary of the regular distribution of the grey (Halichoerus grypus and ringed Phoca hispida) seal in the Baltic Sea. During the annual molt period in May–June (in the Estonian coastal waters), the stock size is estimated to be 1200–1500 grey seal individuals – that is, roughly 25% of the whole Baltic population. If we compare the chlororganic contents of seals in different areas the Baltic Sea, we can see that the northern part of the Gulf of Riga and Väinameri Sea is the reference area of the Baltic Sea.     

A Survey Technique for Determining The Representativeness of Urban Air Monitoring Stations With Respect to Carbon Monoxide

An air quality survey technique for measuring the horizontal spatial variation of carbon monoxide concentrations in urban areas is described; it was used to determine how representative an urban air monitoring station is of concentrations throughout the city.

The survey technique was applied in San Jose, Calif., where 1128 samples were collected over a six-month period and were compared with the values recorded simultaneously at the urban air monitoring station. All samples were collected at “breathing height” within a 13-square-mile grid which included the downtown area as well as surrounding residential and industrial locations. Three basic sampling strategies were employed to answer specific questions about the distribution of carbon monoxide concentration: (7) walking sampling, in which samples were obtained while walking along the sidewalks of congested downtown streets, (2) random spatial sampling, in which samples were collected at randomly selected points in the urban grid, and (3) specialized sampling in the immediate vicinity of the air monitoring station.

The results indicate that pedestrians on downtown streets in San Jose can be exposed to concentrations above the federal air quality standards without these values being observed at the air monitoring station. There also is evidence that, at any instant of time, similar values of carbon monoxide exist throughout this city (within a 13-square mile area), provided that measurements are not made in close proximity to streets. Furthermore, the higher concentrations observed in the immediate vicinity of streets decrease quite rapidly with increasing horizontal distance from these streets.

These findings, in the view of the authors, raise serious doubts as to whether it is possible to determine if air quality standards as currently defined are actually being met in urban areas using data from present-day air monitoring stations.     

Determination of response of real-time SidePak AM510 monitor to secondhand smoke, other common indoor aerosols, and outdoor aerosol

The amount of light scattered by airborne particles inside an aerosol photometer will vary not only with the mass concentration, but also with particle properties such as size, shape, and composition. This study conducted controlled experiments to compare the measurements of a real-time photometer, the SidePak AM510 monitor (SidePak), with gravimetric mass. PM sources tested were outdoor aerosols, and four indoor combustion sources: cigarettes, incense, wood chips, and toasting bread. The calibration factor for rescaling the SidePak measurements to agree with gravimetric mass was similar for the cigarette and incense sources, but different for burning wood chips and toasting bread. The calibration factors for ambient urban aerosols differed substantially from day to day, due to variations in the sources and composition of outdoor PM. A field evaluation inside a casino with active smokers yielded calibration factors consistent with those obtained in the controlled experiments with cigarette smoke.     

The effect of opening windows on air change rates in two homes

More than 300 air change rate experiments were completed in two occupied residences: a two-story detached house in Redwood City, CA, and a three-story townhouse in Reston, VA. A continuous monitor was used to measure the decay of SF6 tracer gas over periods of 1-18 hr. Each experiment first included a measurement of the air change rate with all exterior doors and windows closed (State 0), then a measurement with the single change from State 0 conditions of opening one or more windows. The overall average State 0 air change rate was 0.37 air changes per hour (hr(-1)) (SD = 0.10 hr(-1); n = 112) for the California house and 0.41 hr(-1) (SD = 0.19 hr(-1); n = 203) for the Virginia house. Indoor/outdoor temperature differences appeared to be responsible for the variation at the Virginia house of 0.15-0.85 hr(-1) when windows were closed. Opening a single window increased the State 0 air change rate by an amount roughly proportional to the width of the opening, reaching increments as high as 0.80 hr(-1) in the California house and 1.3 hr(-1) in the Virginia house. Multiple window openings increased the air change rate by amounts ranging from 0.10 to 2.8 hr(-1) in the California house and from 0.49 to 1.7 hr(-1) in the Virginia house. Compared with temperature differences and wind effects, opening windows produced the greatest increase in the air change rates measured in both homes. Results of this study indicate the importance of occupant window-opening behavior on a home's air change rate and the consequent need to incorporate this factor when estimating human exposure to indoor air pollutants.     

Progress Toward a Uniform Air Pollution Index

Recently, various authors^1–4 have indicated that a need exists to establish a uniform air pollution index for communities throughout the nation.Although the literature reveals several attempts to develop air pollution indices,^5–7 none of these indices has received widespread acceptance by state and local air pollution control agencies, probably because none has received the active support or endorsement of the federal government. We now wish to report that significant progress has been made at the federal level toward the goal of a recommended national air pollution index.