Ambient Air Quality Monitoring Network Design for Assessing Human Health Impacts from Exposures to Airborne Contaminants

Existing methods of establishing ambientair quality monitoring networks typically evaluateonly parameters related to ambient concentrations ofthe contaminant(s) of interest such as emissionsource characteristics, atmospheric transport anddispersion, secondary reactions, depositioncharacteristics, and local topography. However,adverse health risks from exposures to airbornecontaminants are a function of the contaminant andthe anatomic and physiologic characteristics of theexposed population. Thus, ambient air qualitymonitoring networks designed for the protection ofpublic health or for epidemiological studiesevaluating adverse health impacts from exposures toambient air contaminants should account for bothcontaminant characteristics and human healthparameters. A methodology has been establishedwhich optimizes ambient air quality monitoringnetworks for assessments of adverse human healthimpacts from exposures to airborne contaminants byincorporating human health risk assessmenttechniques. The use of risk assessment techniquesas the basis for designing ambient air qualitymonitoring networks will help to target limitedfinancial and human resources to evaluate humanhealth risks from exposures to airbornecontaminants.     

Environmental monitoring of historical change in arsenic deposition with tree bark pockets

ICP-MS analysis recorded historical change (c. 1846 to 2002) in the arsenic concentration of bark included within the trunks (tree bark pockets) of two Japanese oak trees (Quercus crispula), collected at an elevated location approximately 10 km from the Ashio copper mine and smelter, Japan. The arsenic concentration of the bark pockets was 0.016 +/- 0.003 microg cm(-2) c. 1846 (n = 5) and rose 50-fold from c. 1875 to c. 1925, from approximately 0.01 to 0.5 microg cm(-2). The rise coincided with increased copper production in Ashio from local sulfide ores, from 46 tons per year in 1877 to 16,500 tons per year in 1929. Following a decline in arsenic concentration and copper production, in particular during the Second World War, a second peak was observed c. 1970, corresponding to high levels of production from both local (6,000 tons per year) and imported (30,000 tons per year) ores, smelted from 1954. Compared to the local ores, the contribution of arsenic from imported ores appeared relatively low. Arsenic concentrations declined from c. 1970 to the present following the closure of the mine in 1974 and smelter in 1989, recording 0.058 +/- 0.040 microg cm(-2) arsenic (n = 5) in surface bark collected in 2002. The coincident trends in arsenic concentration and copper production indicated that the bark pockets provided an effective record of historical change in atmospheric arsenic deposition.     

A Method of Predicting Point and Path- Averaged Ambient Air VOC Concentrations,Using Meteorological Data

A method of predicting point and path-averaged ambient air VOC concentrations is described. This method was developed for the case of a plume generated from a single point source, and is based on the relationship between wind directional frequency and concentration. One-minute means of wind direction and wind speed were used as inputs to a Gaussian dispersion model to develop this relationship.

Both FTIR spectrometry and a whole-air sampling method were used to monitor VOC plumes during simulated field tests. One test set was also conducted using only whole-air samplers deployed in a closely-spaced network, thus providing an evaluation of the prediction technique free of any bias that might exist between the two analytical methods.

Correlations between observed point concentrations and wind directional frequencies were significant at the 0.05 level in most cases. Predicted path-integrated concentrations, based on observed point concentrations and meteorological data, were strongly correlated with observed values. Predicted point concentrations, based on observed path-integrated concentrations and meteorological data, accurately reflected the location and magnitude of the highest concentrations from each test, as well as the shape of the concentration-versus-crosswind distance curve.     

N-nitrosodimethylamine and trihalomethane formation and minimisation in Southeast Queensland drinking water

This study assesses the prevalence of disinfection by-product (DBP) precursors in some Southeast Queensland drinking water sources by conducting formation potential experiments for the four regulated trihalomethanes (THMs), and the potent carcinogen, N-nitrosodimethylamine (NDMA). NDMA formation potentials were consistently low (<5-21 ng/L), and total THM (tTHM) formation potentials were consistently below the Australian Drinking Water Guideline (250 μg/L). NDMA concentration of finished drinking waters was also monitored and found to be <5 ng/L in all cases. The effect of coagulation and advanced oxidation on the formation of NDMA and THMs is also reported. UV/H(2)O(2) pre-treatment was effective in producing water with very low THMs concentrations, and UV irradiation was an effective method for NDMA degradation. H(2)O(2) was not required for the observed NDMA degradation to occur. Coagulation using alum, ferric chloride or poly(diallyldimethylammonium chloride) (polyDADMAC) was ineffective in removing DBPs precursors from the source water studied, irrespective of the low dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) attained. Rather, coagulation with polyDADMAC caused an increase in NDMA formation potential upon chloramination, and all coagulants led to an increased tTHM formation potential upon chlorination due to the high bromide concentration of the source water studied.     

Accuracy assessment of land surface temperature retrievals from Landsat 7 ETM + in the Dry Valleys of Antarctica using iButton temperature loggers and weather station data

The McMurdo Dry Valleys of Antarctica are the largest snow/ice-free regions on this vast continent, comprising 1 % of the land mass. Due to harsh environmental conditions, the valleys are bereft of any vegetation. Land surface temperature is a key determinate of microclimate and a driver for sensible and latent heat fluxes of the surface. The Dry Valleys have been the focus of ecological studies as they arguably provide the simplest trophic structure suitable for modelling. In this paper, we employ a validation method for land surface temperatures obtained from Landsat 7 ETM + imagery and compared with in situ land surface temperature data collected from four transects totalling 45 iButtons. A single meteorological station was used to obtain a better understanding of daily and seasonal cycles in land surface temperatures. Results show a good agreement between the iButton and the Landsat 7 ETM + product for clear sky cases. We conclude that Landsat 7 ETM + derived land surface temperatures can be used at broad spatial scales for ecological and meteorological research.     

Conservation Opportunities for Securing In-Stream Flows in the Platte River Basin: A Case Study Drawing on Casper,Wyoming’s MunicipalWater Strategy

The Platte River Basin consists of tributaries largely in Wyoming, Colorado and Western Nebraska, with the main stem in Central Nebraska. Critical wildlife habitat on the main stem requires additional in-stream flows. The watershed is one hosting multiple resources, a variety of users, and managed by an array of state and federal agencies. This study proposes a basis for securing in-stream flows for the Platte River. Candidate water supply mechanisms are suggested based on the way in which Casper, Wyoming secured water for its municipal needs. Canal lining is compared to a dam project, increasing reservoir storage, and purchasing water rights, with consideration also made for water pricing to reduce municipal use. Comparisons are based on economic efficiency, potential water conservation, and property rights criteria. Canal lining, coupled with demand management, is shown to conserve water best, given the set of efficiency and cost criteria for in-stream flow enhancement. The approach offers an opportunity to organize the water supply choice context in a transboundary watershed when quantitative information is limited.     

A MANGANESE OXIDATION MODEL FOR RIVERS1

ABSTRACT: The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.     

TREE RING RECONSTRUCTIONS OF STREAMFLOW FOR THREE CANADIAN PRAIRIE RIVERS1

ABSTRACT: Information regarding long term hydrological variability is critical for the effective management of surface water resources. In the Canadian Prairie region, growing dependence on major river systems for irrigation and other consumptive uses has resulted in an increasing vulnerability to hydrological drought and growing interprovincial tension. This study presents the first dendrochronological records of streamflow for Canadian Prairie rivers. We present 1,113‐year, 522‐year, and 325‐year reconstructions of total water year (October to September) streamflow for the North Saskatchewan, South Saskatchewan, and Saskatchewan Rivers, respectively. The reconstructions indicate relatively high flows during the 20th Century and provide evidence of past prolonged droughts. Low flows during the 1840s correspond with aridity that extended over much of the western United States. Similarly, an exceptional period of prolonged low flow conditions, approximately 900 A.D. to 1300 A.D., is coincident with evidence of sustained drought across central and western North America. The 16th Century megadrought of the western United States and Mexico, however, does not appear to have had a major impact on the Canadian rivers. The dendrohydrological records illustrate the risks involved if future water policy and infrastructure development in the Canadian Prairies are based solely on records of streamflow variability over the historical record.