A comparison of portable XRF and ICP-OES analysis for lead on air filter samples from a lead ore concentrator mill and a lead-acid battery recycler

Personal and area samples for airborne lead were taken at a lead mine concentrator mill, and at a lead-acid battery recycler. Lead is mined as its sulfidic ore, galena, which is often associated with zinc and silver. The ore typically is concentrated, and partially separated, on site by crushing and differential froth flotation of the ore minerals before being sent to a primary smelter. Besides lead, zinc and iron are also present in the airborne dusts, together with insignificant levels of copper and silver, and, in one area, manganese. The disposal of used lead-acid batteries presents environmental issues, and is also a waste of recoverable materials. Recycling operations allow for the recovery of lead, which can then be sold back to battery manufacturers to form a closed loop. At the recycling facility lead is the chief airborne metal, together with minor antimony and tin, but several other metals are generally present in much smaller quantities, including copper, chromium, manganese and cadmium. Samplers used in these studies included the closed-face 37 mm filter cassette (the current US standard method for lead sampling), the 37 mm GSP or "cone" sampler, the 25 mm Institute of Occupational Medicine (IOM) inhalable sampler, the 25 mm Button sampler, and the open-face 25 mm cassette. Mixed cellulose-ester filters were used in all samplers. The filters were analyzed after sampling for their content of the various metals, particularly lead, that could be analyzed by the specific portable X-ray fluorescence (XRF) analyzer under study, and then were extracted with acid and analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The 25 mm filters were analyzed using a single XRF reading, while three readings on different parts of the filter were taken from the 37 mm filters. For lead at the mine concentrate mill, all five samplers gave good correlations (r2 > 0.96) between the two analytical methods over the entire range of found lead mass, which encompassed the permissible exposure limit of 150 mg m(-3) enforced in the USA by the Mine Safety and Health Administration (MSHA). Linear regression on the results from most samplers gave almost 1 ratio 1 correlations without additional correction, indicating an absence of matrix effects from the presence of iron and zinc in the samples. An approximately 10% negative bias was found for the slope of the Button sampler regression, in line with other studies, but it did not significantly affect the accuracy as all XRF results from this sampler were within 20% of the corresponding ICP values. As in previous studies, the best results were obtained with the GSP sampler using the average of three readings, with all XRF results within 20% of the corresponding ICP values and a slope close to 1 (0.99). Greater than 95% of XRF results were within 20% of the corresponding ICP values for the closed-face 37 mm cassette using the OSHA algorithm, and the IOM sampler using a sample area of 3.46 cm2. As in previous studies, considerable material was found on the interior walls of all samplers that possess an internal surface for deposition, at approximately the same proportion for all samplers. At the lead-acid battery recycler all five samplers in their optimal configurations gave good correlations (r2 > 0.92) between the two analytical methods over the entire range of found lead mass, which included the permissible exposure limit enforced in the USA by the Occupational Safety and Health Administration (OSHA). Linear regression on the results from most samplers gave almost 1 ratio 1 correlations (except for the Button sampler), indicating an absence of matrix effects from the presence of the smaller quantities of the other metals in the samples. A negative bias was found for the slope of the button sampler regression, in line with other studies. Even though very high concentrations of lead were encountered (up to almost 6 mg m(-3)) no saturation of the detector was observed. Most samplers performed well, with >90% of XRF results within +/- 25% of the corresponding ICP results for the optimum configurations. The OSHA algorithm for the CFC worked best without including the back-up pad with the filter.     

EFFECTIVENESS OF BIOPHYSICAL CRITERIA IN THE HIERARCHICAL CLASSIFICATION OF DRMNAGE BASINS1

ABSTRACT: A subwatershed base map of 84 hydrologic subregions within the Columbia River Basin (approximately 58,361,000 ha) was developed following hierarchical principles of ecological unit mapping. Our primary objectives were to inspect the relations between direct and indirect biophysical variables in the prediction of valley bottom and stream type patterns, and to identify hydrologic subregions (based on these results) that had similar aquatic patterns for which consistent management practices could be applied. Realization of these objectives required: (1) stratified subsampling of valley bottom and stream type composition within selected sub‐watersheds, (2) identification of direct and indirect biophysical variables that were mappable across the basin and that exerted primary control on the distribution of sampled aquatic patterns, and (3) development of hydrologic subregion maps based on the primary biophysical variables identified. Canonical correspondence analysis indicated that a core set of 15 direct variables (e.g., average watershed slope, drainage density, ten‐year peak flow) and 19 indirect variables (i.e., nine subsection groups, four lithology groups, and six potential vegetation settings) accounted for 31 and 30 percent (respectively) of valley bottom/stream type composition variability and 84 and 80 percent (respectively) of valley bottom/stream type environmental variability within subsamples. The 19 indirect biophysical variables identified were used to produce an ecological unit classification of 7,462 subwatersheds within the basin by a hierarchical agglomerative clustering technique (i.e., hydrologic subregions were identified). Discriminant analysis indicated that 13 direct biophysical variables could correctly assign 80 percent of the subwatersheds to their indirect biophysical classification, thus demonstrating the strong relation that exists between indirect biophysical based classifications (ecological units) and the direct biophysical variables that determine finer‐level aquatic patterns. Our hydrologic subregion classifications were also effective in explaining observed differences in management hazard ratings across all subwatersheds of the basin. Results of this research indicate that ecological units can be effectively used to produce watershed classifications that integrate the effects of direct biophysical variables on finer‐level aquatic patterns, and predict opportunities and limitations for management.     

Volatile organic compounds concentrations in residential indoor and outdoor and its personal exposure in Korea

To date, personal volatile organic compounds (VOCs) exposure and residential indoor and outdoor VOCs levels have not been characterized in Korea. In this study, residential indoor and outdoor VOCs concentrations were measured and compared simultaneously with the personal exposure for each of 30 participants in a medium city, Asan, and in a metropolitan city, Seoul. Factors that influence personal VOCs exposures were assessed in relation to house characteristics and time activity information. All VOC concentrations were measured using passive samplers during a 24-h period and analyzed using GC-MS. Ten target VOCs were benzene, trichloroethylene, toluene, o-xylene, p-xylene, ethylbenzene, MIBK, n-octane, styrene, and 1,2-dichlorobenzene. Residential indoor and outdoor VOCs concentrations measured in Seoul were significantly higher than those in Asan. Indoor/outdoor (I/O) ratios for all target compounds ranged from 0.94 to 1.51 and I/O ratios of Asan were a little higher than those of Seoul. Results indicate that time activity information can be used to predict personal exposures, although such predictions will result in an over estimation compared to measured exposures. Factors which influence the indoor VOCs level and its personal exposure in relation to house characteristics included house age, indoor smoking, and house type.     

Anti-predatory vigilance and the limits to collective detection: visual and spatial separation between foragers

Collective detection concerns the idea that all members of a socially feeding group are alerted to an attack as long as at least one group member detects it. We found that collective detection in mixed flocks of emberizid sparrows is limited markedly by relatively small degrees of visual and spatial separation between foragers. These limits on collective detection appear to influence the degree to which flock members lower their vigilance with increasing group size (the group size effect). Specifically, the decrease in collective detection with increasing visual and spatial isolation between foragers is accompanied by a concomitant decrease in the strength of the vigilance group size effect. Explanations for the vigilance-related effects of such separation based upon a bird’s ability to monitor the vigilance behavior of flockmates can be ruled out for our experimental system. Our results also shed light on the issue of whether the vigilance group size effect is influenced more by collective detection or the simple dilution of risk with increasing group size. We argue that collective detection is not only an important determinant of the group size effect, but also that the phenomena of collective detection and risk dilution are interdependent. Received: 25 July 1995/Accepted after revision: 17 December 1995     

Some of the Nineteenth Century Origins of the Sustainability Concept

Interpreting and applying the concept of sustainable development is increasingly viewed as being the way to promulgate just and practicable economic, environmental and social policy. It is thus important that there be increased public and political awareness concerning the origins of economic theory, and its early relationship to sustainability concepts. While the term 'sustainable development' was popularised by the World Commission on Environment and Development report Our Common Future in 1987, it is generally recognised that notions of sustainability were promoted in `limits to growth' and 'green' discourses in the early 1970s (Meadows et al.: 1974, The Limits to Growth: A Report for the Club of Rome, Potomac Associates and Pan Books, London and Sydney). However, there is little acknowledgement of the way in which nineteenth century intellectuals, from a range of disciplines, conceptualised the importance of balancing economic, social and environmental sustainability in their quest for justice and the conservation of nature.There was a considerable exchange of ideas on `political economy' and nature across Europe, and later the Americas, from the middle of the eighteenth century. This discourse reached its intellectual peak in the nineteenth century. During that era there was a proliferation of literature that was aimed at improving the human condition and recognising humanity's dependence upon nature. In Europe and the USA the participants in the debate included Cantillon, Quesnay, Condorcet, Galiani, Von Hayek, Marx and George. Due to the breadth of this influential body of work, we focus here on the British Victorian thinkers such as Darwin, Malthus, Martineau and Mill. These thinkers influenced each other in developing their theories and ideas in science, politics, economics and philosophy, and were influenced in turn by an earlier generation of intellectuals, such as Adam Smith. For the Victorian thinkers, conserving nature while trying to improve the distribution of wealth was a not a paradox, but a moral duty, and for them Smith's `rational' pursuit of self-interest could only be followed if it did not interfere with 'the rules of justice'. We argue that the manner in which these thinkers conceptualised their theories and ideas represents the nineteenth century origins of sustainability concepts.     

Eclogites with a short-lived granulite facies overprint in the Moldanubian Zone, Czech Republic: petrology, geochemistry and diffusion modelling of garnet zoning

The petrology and geochemistry of a newly discovered suite of high-pressure garnet + clinopyroxene-bearing rocks from the Monotonous Series of the Moldanubian Zone of the Bohemian Massif, southwest Czech Republic have been investigated. Three types [common eclogites, quartz ± kyanite ± (clino)zoisite eclogites and garnet-hornblende-clinopyroxenites] are distinguished by petrography and geochemistry. All underwent a significant degree of partial breakdown under granulite and amphibolite facies conditions during exhumation. Important features include the growth of orthopyroxene in breakdown domains after garnet and omphacite and anorthite + spinel ± corundum ± exceedingly peraluminous sapphirine replacing kyanite. Garnet zoning and inclusion patterns support a prograde evolution from low pressures for at least some of the samples. The post-eclogite stage granulite facies overprint indicates that high temperatures prevailed during exhumation, but preservation of zoning in some garnets and the results of diffusion modelling suggest that this overprint took place over a very short time-scale. The geochemical and petrological results allow characteristic differences to be recognized between these eclogites and metabasites found in other tectonic units of South Bohemia and consequently the assigning of all high-pressure rocks to a single, now disrupted, tectonic unit is a gross simplification that seriously misrepresents the tectono-metamorphic history of the region.     

EFFECT OF pH ON PHOSPHORUS RELEASE DURING MACROPHYTE (ELEOCHARIS sp.) DECOMPOSITION1

ABSTRACT: Laboratory microcosms were used to evaluate the effect of pH on release of soluble reactive phosphorus (SRP) during aerobic decomposition of the aquatic macrophyte Eleocharis sp., which is common in oligotrophic Florida lakes. The total amount of SRP released during a 227-day incubation in the dark was independent of pH over the range 3.7 to 5.5, but initial rates of release were faster at the lowest pH. The results indicate that the low total phosphorus concentrations observed in many acidic lakes are not necessarily attributable to reduced rates of decomposition and nutrient mineralization at low pH, as some researchers have suggested.     

Application of nutrient loading models to the analysis of trophic conditions in Lake Okeechobee,Florida

Lake Okeechobee (surface area = 1830 km², mean depth = 3.5 m), the largest lake in Florida, is eutrophic and has nitrogen and phosphorus loading rates in excess of nearly all established criteria. The lake is not homogeneous regarding trophic conditions, and spatial and temporal variations occur regarding nutrient limitation. Nonetheless, phosphorus loading rate and trophic state data fit reasonably well to various input-output models developed for temperate lakes. Modification of the models by regression analysis to fit data for Florida lakes resulted in improved predictions for most parameters. Analysis of nutrient management alternatives for the lake indicates that a 75% reduction of phosphorus loading from the largest source (the Taylor Creek-Nubbins Slough watershed) would reduce the average chlorophyll a concentration by less than 20%. Complete elimination of inputs from the largest nitrogen source (the Everglades Agricultural Area) would decrease the average nitrogen concentration in the lake by about 20%. Limitations of nutrient inputoutput models regarding analysis of trophic conditions and management alternatives for the lake are discussed.     

Assessing the Impact of Carbon Tax Differentiation in the European Union

To what extent do the welfare costs associated with the implementation of the Burden Sharing Agreement in the European Union depend on sectoral allocation of emissions rights? What are the prospects for strategic climate policy to favor domestic production? This paper attempts to answer those questions using a CGE model featuring a detailed representation of the European economies. First, numerical simulations show that equalizing marginal abatement costs across domestic sectors greatly reduces the burden of the emissions constraint but also that other allocations may be preferable for some countries because of pre-existing tax distortions. Second, we show that the effect of a single country's attempt to undertake a strategic policy to limit impacts on its domestic energy-intensive industries has mixed effects. Exempting energy-intensive industries from the reduction program is a costly solution to maintain the international competitiveness of these industries; a tax-cum-subsidy approach is shown to be better than exemption policy to sustain exports. The welfare impact either policy – exemption or subsidy – on other European countries is likely to be small because of general equilibrium effects.