Interlaboratory evaluation of trace element determination in workplace air filter samples by inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) is becoming more widely used for trace elemental analysis in the occupational hygiene field, and consequently new ICP-MS international standard procedures have been promulgated by ASTM International and ISO. However, there is a dearth of interlaboratory performance data for this analytical methodology. In an effort to fill this data void, an interlaboratory evaluation of ICP-MS for determining trace elements in workplace air samples was conducted, towards fulfillment of method validation requirements for international voluntary consensus standard test methods. The study was performed in accordance with applicable statistical procedures for investigating interlaboratory precision. The evaluation was carried out using certified 37-mm diameter mixed-cellulose ester (MCE) filters that were fortified with 21 elements of concern in occupational hygiene. Elements were spiked at levels ranging from 0.025 to 10 μg filter(-1), with three different filter loadings denoted "Low", "Medium" and "High". Participating laboratories were recruited from a pool of over fifty invitees; ultimately twenty laboratories from Europe, North America and Asia submitted results. Triplicates of each certified filter with elemental contents at three different levels, plus media blanks spiked with reagent, were conveyed to each volunteer laboratory. Each participant was also provided a copy of the test method which each participant was asked to follow; spiking levels were unknown to the participants. The laboratories were requested to prepare the filters by one of three sample preparation procedures, i.e., hotplate digestion, microwave digestion or hot block extraction, which were described in the test method. Participants were then asked to analyze aliquots of the prepared samples by ICP-MS, and to report their data in units of μg filter(-1). Most interlaboratory precision estimates were acceptable for medium- and high-level spikes (RSD <25%), but generally yielded greater uncertainties than were anticipated at the outset of the study.     

Demonstrations of coal-fired oxy-fuel technology for carbon capture and storage and issues with commercial deployment

As one of the three major carbon capture technologies associated with carbon capture and storage (CCS), oxy-fuel technology is currently undergoing rapid development with a number of international demonstration projects of scale 10–30 MW_e having commenced and units with a scale of 250–300 MW_e emerging in the progression towards commercialisation. Industrial scale testing of coal combustion and burners is also being conducted by technology vendors.The paper details the current international status of the technology; the contributions of current demonstrations; and a roadmap for commercial deployment.At its current state of maturity oxy-fuel technology may be considered semi-commercial, in that even if a unit was economically viable and could be provided by a vendor, the generator and vendor would need to share the technical risk. This is because guarantees could not at present be provided for operating characteristics associated with mature technologies such as reliability, emissions, ramp rate and spray control. This is due to the maturity of the technology associated with the capability of vendors and associated design and operational uncertainties, associated with a lack of plant experience at scale.The projected development of oxy-fuel technology for first-generation plant is provided, using an ASU for oxygen supply, standard furnace designs with externally recirculated flue gas, and limited thermal integration of the ASU and compression plant with the power plant. Potential features of second generation technology are listed.Listed issues delaying deployment indicate that market, economic, legal and issues of public acceptance are more significant than technical barriers.     

WATER YIELD AUGMENTATION THROUGH FOREST AND RANGE MANAGEMENT - ISSUES FOR THE FUTURE1

The demand for more water is increasing throughout the country. Research on upland watersheds clearly demonstrates that water yield can be increased using forest and range management practices. Based on the experience of the past several decades and a review of six papers in a recent AWRA series on water yield augmentation through vegetation management, the following issues and concerns are discussed: predicting increased yields from large basins; economic evaluation of additional flows; court acceptance and need for system models; the legal question of ownership and transferability of increased yields; and management emphasis on private and federal lands. The immediate potential for water yield augmentation is on carefully selected watersheds that have the bio-physical potential to produce high value water under environmentally acceptable multiple use management. We predict water yield management on a broader scale will result from increased pressures to solve the legal and economic issues involved.     

PRECIPITATION CHANGES FROM 1956 TO 1996 ON THE WALNUT GULCH EXPERIMENTAL WATERSHED1

ABSTRACT: The climate of Southern Arizona is dominated by summer precipitation, which accounts for over 60 percent of the annual total. Summer and non‐summer precipitation data from the USDA‐ARS Walnut Gulch Experimental Watershed are analyzed to identify trends in precipitation characteristics from 1956 to 1996. During this period, annual precipitation increased. The annual precipitation increase can be attributed to an increase in precipitation during non‐summer months, and is paralleled by an increase in the proportion of annual precipitation contributed during non‐summer months. This finding is consistent with previously reported increases in non‐summer precipitation in the southwestern United States. Detailed event data were analyzed to provide insight into the characteristics of precipitation events during this time period. Precipitation event data were characterized based on the number of events, event precipitation amount, 30‐minute event intensity, and event duration. The trend in non‐summer precipitation appears to be a result of increased event frequency since the number of events increased during nonsummer months, although the average amount per event, average event intensity, and average event duration did not. During the summer “monsoon” season, the frequency of recorded precipitation events increased but the average precipitation amount per event decreased. Knowledge of precipitation trends and the characteristics of events that make up a precipitation time series is a critical first step in understanding and managing water resources in semiarid ecosystems.     

HEAVY RAINSTORMS IN CHICAGO: INCREASING FREQUENCY,ALTERED IMPACTS,AND FUTURE IMPLICATIONS1

ABSTRACT: Operations of a dense raingage network in the Chicago area since 1989 provided data to assess the temporal and spatial distributions of heavy rainstorms. The 12‐year average was 4.4 storms per year, 40 percent more than in the 1948 to 1980 period, reflecting an ongoing Midwestern increase in heavy rains. The total rainfall from the 53 heavy rainstorms maximized over the city, reflecting previous observations that the influence of the city and Lake Michigan on the atmosphere causes an increase in heavy rains. Impacts from the record high number of eight storms in 2001 revealed that efforts to control flooding including the Deep Tunnel system, had reduced street and basement flooding in the moderate intensity storms, but the two most intense storms, each with 100‐year rainfall values, led to excessive flooding and a need to release flood waters into Lake Michigan. Results suggest continuing increases in the number of heavy rainstorms in future years, which has major implications for water managers in Chicago and elsewhere.     

TEODORO ARDEMANS PIONEER WATER-SUPPLY ENGINEER OF SPAIN1

ABSTRACT: Teodoro Ardemans, first post-Renaissance water expert of Spain, recognized problems of ground-water contamination, influence of minerals on water quality, and mutual interference between closely spaced wells. He is also noted for his achievements in architecture and the writing of the first comprehensive building code for Madrid.     

POTENTIAL EFFECTS OF CHANGED CLIMATES ON HEAVY RAINFALL FREQUENCIES IN TIlE MIDWEST1

ABSTRACT: An important question posed by potential future shifts in climate relates to possible shifts in heavy rainfall events (intensity and/or frequency) used to design hydraulic structures. Heavy rain events were defined as those producing amounts having average recurrence intervals of two years or longer for a specific storm period at a given location. Estimates of such heavy rainfall shifts in the humid continental climate of the midwest were derived by using spatial and temporal analogs. Comparisons in areas of relatively warm, wet conditions were made with those having measurably cooler, drier average conditions. The spatial-temporal analogs provided comparative differences in precipitation and temperature similar to the magnitude of changes obtained from GCM estimates. Spatial analogs/analyses indicated 10 to 15 percent increases in the frequency distribution of rain events having recurrence intervals of 5 to 50 years. Two periods of notably drier and warmer conditions during the past 90 years revealed 5 to 15 percent decreases in the number of 2- to 10-year heavy rain events. The suppression percentages showed a strong tendency to increase with increasing recurrence interval from 2 to 10 years.     

Effectiveness of primary enforcement safety belt laws and enhanced enforcement of safety belt laws: a summary of the Guide to Community Preventive Services systematic reviews

BACKGROUND: The use of safety belts is the single most effective means of reducing fatal and nonfatal injuries in motor-vehicle crashes. This paper summarizes the systematic reviews of two interventions to increase safety belt use: primary enforcement safety belt laws and enhanced enforcement of safety belt laws. The reviews were previously published in the American Journal of Preventive Medicine. METHODS: We conducted the systematic reviews using the methodology developed for the Guide to Community Preventive Services. RESULTS: These reviews provide strong evidence that primary laws are more effective than secondary laws in increasing safety belt use and decreasing fatalities and that enhanced enforcement is effective in increasing safety belt use. Increases in belt use are generally highest in states with low baseline rates of belt use. DISCUSSION: Primary safety belt laws and enhanced enforcement programs tend to result in greater increases in usage rates for target groups with lower baseline rates. Concerns regarding public opposition to these interventions may impede their implementation in some jurisdictions. However, surveys indicate that a substantial majority of the public supports implementation of both primary laws and enhanced enforcement programs. CONCLUSION: Based on the strong evidence for effectiveness of primary safety belt laws and enhanced enforcement programs, the Task Force on Community Preventive Services recommended that all states enact primary safety belt laws and that communities implement enhanced enforcement programs.     

Biosorption of copper (II) from chemical mechanical planarization wastewaters

Copper Chemical Mechanical Planarization (Cu-CMP) is a critical step in integrated circuit (IC) device manufacturing. CMP and post-CMP cleaning processes are projected to account for 30-40% of the water consumed by IC manufacturers in 2003. CMP wastewater is expected to contain increasing amounts of copper as the industry switches from Al-CMP to Cu-CMP causing some IC manufacturers to run the risk of violating discharge regulations. There are a variety of treatment schemes currently available for the removal of heavy metals from CMP wastewater, however, many introduce additional chemicals to the wastewater, have large space requirements, or are expensive. This work explores the use of microorganisms for waste treatment. A Staphylococcus sp. of bacteria was isolated and studied to determine the feasibility for use in removing copper from Cu-CMP wastewater. A model Cu-CMP wastewater was developed and tested, as well as actual Cu-CMP wastes. Continuous-flow packed column experiments were performed to obtain adsorption data and show copper recovery from the waste. A predictive, empirical model was used to accurately describe Cu removal. Additionally, the immobilized cells were regenerated, allowing for the concentration and potential recovery of copper from the wastewater.     

Implications of fluoride--an endless uncertainty

Fluorosis has become pandemic and it has assumed global status in the public health point of view. The paper deals with the health issues pertaining to fluorosis with special emphasis in the Indian context. It explains the equivocal evidences of fluoride-related problems and discusses the control measures of fluorosis. In general, it reveals how fluoride is useful at very low concentrations and at the same time brings forth manifestation of clinical abnormalities at higher concentrations that are the basis of the principles of toxicology.