Influence of ship emissions on air quality and input of contaminants in southern Alaska National Parks and Wilderness Areas during the 2006 tourist season

The impact of ship emissions on air quality in Alaska National Parks and Wilderness Areas was investigated using the Weather Research and Forecasting model inline coupled with chemistry (WRF/Chem). The visibility and deposition of atmospheric contaminants was analyzed for the length of the 2006 tourist season. WRF/Chem reproduced the meteorological situation well. It seems to have captured the temporal behavior of aerosol concentrations when compared with the few data available. Air quality follows certain predetermined patterns associated with local meteorological conditions and ship emissions. Ship emissions have maximum impacts in Prince William Sound where topography and decaying lows trap pollutants. Along sea-lanes and adjacent coastal areas, NO_x, SO₂, O₃, PAN, HNO₃, and PM_2.5 increase up to 650 pptv, 325 pptv, 900 pptv, 18 pptv, 10 pptv, and 100 ng m^?3. Some of these increases are significant (95% confidence). Enhanced particulate matter concentrations from ship emissions reduce visibility up to 30% in Prince William Sound and 5–25% along sea-lanes.     

Comparison of real-time instruments used to monitor airborne particulate matter

Measurements collected using five real-time continuous airborne particle monitors were compared to measurements made using reference filter-based samplers at Bakersfield, CA, between December 2, 1998, and January 31, 1999. The purpose of this analysis was to evaluate the suitability of each instrument for use in a real-time continuous monitoring network designed to measure the mass of airborne particles with an aerodynamic diam less than 2.5 microns (PM2.5) under wintertime conditions in the southern San Joaquin Valley. Measurements of airborne particulate mass made with a beta attenuation monitor (BAM), an integrating nephelometer, and a continuous aerosol mass monitor (CAMM) were found to correlate well with reference measurements made with a filter-based sampler. A Dusttrak aerosol sampler overestimated airborne particle concentrations by a factor of approximately 3 throughout the study. Measurements of airborne particulate matter made with a tapered element oscillating microbalance (TEOM) were found to be lower than the reference filter-based measurements by an amount approximately equal to the concentration of NH4NO3 observed to be present in the airborne particles. The performance of the Dusttrak sampler and the integrating nephelometer was affected by the size distribution of airborne particulate matter. The performance of the BAM, the integrating nephelometer, the CAMM, the Dusttrak sampler, and the TEOM was not strongly affected by temperature, relative humidity, wind speed, or wind direction within the range of conditions encountered in the current study. Based on instrument performance, the BAM, the integrating nephelometer, and the CAMM appear to be suitable candidates for deployment in a real-time continuous PM2.5 monitoring network in central California for the range of winter conditions and aerosol composition encountered during the study.     

Benchmarking environmental audit programs: Best practices and biggest challenges

As Total Quality Management (TQM) has become an important concept in learning how to manage environmental, health, and safety audit programs more effectively, an especially useful. TQM tool has been competitive benchmarking. Companies are using benchmarking studies to identify “best practices” that could be incorporated into their programs. In conducting benchmarking studies, evaluators often also identify the biggest common challenges facing audit program managers. This article discusses these best practices and biggest challenges associated with environmental audit programs. The conclusions are based on a number of benchmarking studies and third-party evaluations of corporate audit programs. As the sources are necessarily limited to the author's own experiences, there are no doubt many other specific best practices that are not discussed in this article. These will surface over time.     

应用时间-活动模式估计儿童个体NOx暴露水平

将时间-活动模式与微环境空气污染物监测相结合估计儿童个体NO_x暴露水平. 分别在北京和青岛两市各选择3所学校监测校园环境污染物,并在每个学校选择10名儿童监测其家庭居室空气中ρ(NO_x)及个体24 h NO_x暴露水平,同时收集其时间-活动信息,采用时间-活动模式估计儿童的个体暴露水平. 交通工具中的NO_x暴露水平可通过校门口空气中ρ(NO_x)和交通工具的污染水平系数(λ)估计.结果表明:利用时间-活动模式模拟的儿童个体24 h NO_x暴露水平为0.041 mg/m3,与调整后的个体暴露实测水平相关性较好(R0.785,P<0.01),差值为(-0.002　6±0.013　0) mg/m3,二者的差异无统计学意义 (t0.139,P>0.05).表明采用时间-活动模式与微环境空气质量监测结果相结合方法估计的儿童NO_x暴露水平与个体实际暴露水平一致.      

Genetic structure in native and non-native populations of the direct-developing gastropod Crepidula convexa

In many marine invertebrate species, larval development plays an important role in population connectivity and gene flow: species with direct benthic development generally show more genetic structure than those with planktonic development. We used nuclear markers (microsatellites) to determine population genetic structure of the direct-developing snail Crepidula convexa (Gastropoda: Calyptraeidae) in seven populations with 15–85 individuals each within its native range of the northwest Atlantic and compared it to Crepidula fornicata, a congener with planktonic development. Our results are consistent with general expectations and previous work in these species with other markers: C. convexa had greater population structure and even at a regional scale shows significant isolation-by-distance, in contrast to C. fornicata. We also genotyped a single population of C. convexa introduced to the northeastern Pacific to investigate the prediction of reduced genetic diversity following introduction (founder effect). We did not find a reduction in genetic diversity, suggesting that this non-native population may be characterized by multiple introductions. This pattern is consistent with many other introduced populations of marine invertebrates, including C. fornicata.     

Aerosol chemical and optical properties during the Mt. Zirkel Visibility Study

Aerosol chemical and optical properties were measured near the Mt. Zirkel Wilderness Area in northwestern Colorado. Six-hour PM2.5 (particles with aerodynamic diameters less than 2.5 microm) mass concentrations and PM2.5 dry particle light scattering at 550 nm averaged 4.6 microg m(-3) and 8.6 Mm(-1), respectively. Sulfates, organic carbon, and geological material were the principle components of particle mass and light scattering. Hygroscopic growth was consistent with that expected for ammonium sulfate aerosols. Size distributions derived from three-wavelength (i.e., 450, 550, and 700 nm) nephelometer data were similar to those measured in other remote areas of the western USA. Quasi-dry chemical light scattering efficiencies derived using Mie theory were 3.6 m2 g(-1) for organic carbon, 2.5 m2 g(-1) for sulfates (ammonium sulfate and ammonium bisulfate), 2.6 m2 g(-1) for ammonium nitrate, and 1.76 m2 g(-1) for geological material. These values are lower than but consistent with previously reported results. Realistic efficiencies could not be derived using the multiple linear regression (MLR) approach.