Partitioning gas tracer tests for measurement of water in municipal solid waste

A key component in the operation of almost all bioreactor landfills is the addition of water to maintain optimal moisture conditions. To determine how much water is needed and where to add it, in situ methods are required to measure water within solid waste. Existing technologies often result in measurements of unknown accuracy, because of the variability of solid waste materials and time-dependent changes in packing density, both of which influence most measurement methods. To overcome these problems, a new technology recently developed by hydrologists for measuring water in the vadose zone--the partitioning gas tracer test--was tested. In this technology, the transport behavior of two gas tracers within solid waste is used to measure the fraction of the void space filled with water. One tracer is conservative and does not react with solids or liquids, while a second tracer partitions into the water and is separated from the conservative tracer during transport. This technology was tested in four different solid waste packings and was capable of determining the volumetric water content to within 48% of actual values, with most measurement errors less than 15%. This technology and the factors that affect its applicability to landfills are discussed in this paper.     

In situ experimental study of carbon monoxide generation by gasoline-powered electric generator in an enclosed space

On the basis of currently available data, approximately 97% of generator-related carbon monoxide (CO) fatalities are caused by operating currently marketed, carbureted spark-ignited gasoline-powered generators (not equipped with emission controls) in enclosed spaces. To better understand and to reduce the occurrence of these fatalities, research is needed to quantify CO generation rates, develop and test CO emission control devices, and evaluate CO transport and exposure when operating a generator in an enclosed space. As a first step in these efforts, this paper presents measured CO generation rates from a generator without any emission control devices operating in an enclosed space under real weather conditions. This study expands on previously published information from the U.S. Consumer Product Safety Commission. Thirteen separate tests were conducted under different weather conditions at half and full generator load settings. It was found that the CO level in the shed reached a maximum value of 29,300 +/- 580 mg/m3, whereas the oxygen (O2) was depleted to a minimum level of 16.2 +/- 0.02% by volume. For the test conditions of real weather and generator operation, the CO generation and the O2 consumption could be expressed as time-averaged generation/consumption rates. It was also found that the CO generation and O2 consumption rates can be correlated to the O2 levels in the space and the actual load output from the generator. These correlations are shown to agree well with the measurements.     

Honorary Memberships

Honorary Memberships are conferred by the Air Pollution Control Association on persons of widely recognized eminence in some part of the field of air pollution control or who have rendered especially meritorious service to the Association. Honorary Memberships were awarded this year to Dr. Leonard Greenburg and Mr. Milton Reizenstein, both past presidents of APCA.     

Quality of roof runoff waters from an urban region (Gda sk, Poland)

The paper presents the results of testing of roof runoff waters from buildings in the city of Gda sk (Poland), carried out as a part of a broader research project aimed at the determination of pollutant levels in precipitation. The analytes determined included volatile organohalogen compounds, petroleum hydrocarbons, Na⁺, K⁺, NH₄⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, NO₂⁻, NO₃⁻, PO₄³⁻, SO₄²⁻ ions, as well as organonitrogen, organophosphorus and organochlorine pesticides. In addition, the toxicity and pH of the samples were examined. The samples were collected over a period of six months, during or immediately following precipitation events. More than half of the samples (25) were found to be toxic, with inhibition exceeding 20%. The toxicity was weakly correlated to the levels of organonitrogen and organophosphorus pesticides in runoff waters. It was established that at least in some cases the roofing material affected the levels of the pollutants found in the samples.     

Levels of organochlorine compounds in spotted dolphins from the Coiba archipelago, Panama

Blubber and skin samples from 63 spotted dolphins (Stenella attenuata) (18 males, 40 females and 5 of unknown sex) were collected by biopsy techniques in the waters of the Coiba archipelago. Blubber was analyzed for organochlorine compounds and skin for gender determination. Mean levels of HCB (hexachlorobenzene), tPCB (polychlorinated biphenyls) and tDDT (dichlorodiphenyltrichloroethane) were 0.064, 2.30 and 6.4 mgkg(-1), respectively. These levels are low and are not considered to represent a threat to the S. attenuata population. No significant differences either in concentrations of HCB, tPCB and tDDT or in PCB profiles were observed between males and females. The ratio tDDT/tPCB was 2.69, indicating predominantly agrarian versus industrial activities in the area. The ratio ppDDE/tDDT was 0.83, a high figure that suggests both a local reduction of DDT inputs and a high rate of DDT degradation. Significant quantitative and qualitative differences were observed between two schools, suggesting intra-population heterogeneity in organochlorine exposure possibly due to demographic segregation.     

Dioxins in adipose tissue of women in Southern Spain

Seventeen polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were quantified in adipose tissue samples of non-occupationally exposed women living in Southern Spain. Geometric mean levels of sum of congeners and WHO(PCDD/F)-TEQ(2005) were 410 and 17.9pgg(-1) fat, respectively. Among PCDDs, octachlorodibenzo-p-dioxin (OCDD) showed the highest concentration with a mean value of 265pgg(-1) fat, followed by 1,2,3,6,7,8-HxCDD (49.3pgg(-1) fat) and 1,2,3,4,6,7,8-HpCDD (45.2pgg(-1) fat). These three congeners were responsible for around 90% of the sum of all PCDD/F congeners in adipose tissue. The geometric mean 2,3,7,8-TCDD value was 1.87pgg(-1) fat. 2,3,4,7,8-PeCDF (8.43pgg(-1) fat) showed the highest concentration among the PCDFs, followed by 1,2,3,4,7,8-HxCDF (4.17pgg(-1) fat) and 1,2,3,6,7,8-HxCDF (3.28pgg(-1) fat), and these three congeners were responsible for 4% of the sum of all studied PCDD/F congeners in adipose tissue and 76% of the sum of ten PCDFs. 1,2,3,7,8,9-HxCDF was the only congener not quantified in any sample, while 1,2,3,4,7,8,9-HpCDF, 1,2,3,7,8-PeCDF, OCDF and 2,3,7,8-TCDF were found in 5, 16, 16 and 19 samples, respectively. All other congeners were quantifiable in all 20 samples. Congeners contributing most to the WHO(PCDD/F)-TEQ(2005) were 1,2,3,7,8-PeCDD (31.6%), 1,2,3,6,7,8-HxCDD (28.3%) and 2,3,4,7,8-PeCDF (14.6%). The body burden of log-transformed WHO(PCDD/F)-TEQ(2005) levels increased with age (B=0.02; 95% CI=0.01, 0.03; p=0.02). Although these adipose tissue PCDD/F levels are similar to previously published findings in Spain and other European countries, further research is needed to determine trends in the exposure of women to these chemical residues.