Submicron Aerosol Composition and Source Contribution across the Kathmandu Valley, Nepal, in Winter

The Kathmandu valley experiences an average wintertime PM1 concentration of ∼100 μg m–3 and daily peaks over 200 μg m–3. We present ambient nonrefractory PM1 chemical composition, and concentration measured by a mini aerosol mass spectrometer (mAMS) sequentially at Dhulikhel (on the valley exterior), then urban Ratnapark, and finally suburban Lalitpur in winter 2018. At all sites, organic aerosol (OA) was the largest contributor to combined PM1 (C-PM1) (49%) and black carbon (BC) was the second largest contributor (21%). The average background C-PM1 at Dhulikhel was 48 μg m–3; the urban enhancement was 120% (58 μg m–3). BC had an average of 6.1 μg m–3 at Dhulikhel, an urban enhancement of 17.4 μg m–3. Sulfate (SO4) was 3.6 μg m–3 at Dhulikhel, then 7.5 μg m–3 at Ratnapark, and 12.0 μg m–3 at Lalitpur in the brick kiln region. Chloride (Chl) increased by 330 and 250% from Dhulikhel to Ratnapark and Lalitpur on average. Positive matrix factorization (PMF) identified seven OA sources, four primary OA sources, hydrocarbon-like (HOA), biomass burning (BBOA), trash burning (TBOA), a sulfate-containing local OA source (sLOA), and three secondary oxygenated organic aerosols (OOA). OOA was the largest fraction of OA, over 50% outside the valley and 36% within. HOA (traffic) was the most prominent primary source, contributing 21% of all OA and 44% of BC. Brick kilns were the second largest contributor to C-PM1, 12% of OA, 33% of BC, and a primary emitter of aerosol sulfate. These results, though successive, indicate the importance of multisite measurements to understand ambient particulate matter concentration heterogeneity across urban regions

Atmospheric Emission Characterization of Marcellus Shale Natural Gas Development Sites

Limited direct measurements of criteria pollutants emissions and precursors, as well as natural gas constituents, from Marcellus shale gas development activities contribute to uncertainty about their atmospheric impact. Real-time measurements were made with the Aerodyne Research Inc. Mobile Laboratory to characterize emission rates of atmospheric pollutants. Sites investigated include production well pads, a well pad with a drill rig, a well completion, and compressor stations. Tracer release ratio methods were used to estimate emission rates. A first-order correction factor was developed to account for errors introduced by fenceline tracer release. In contrast to observations from other shale plays, elevated volatile organic compounds, other than CH₄ and C₂H₆, were generally not observed at the investigated sites. Elevated submicrometer particle mass concentrations were also generally not observed. Emission rates from compressor stations ranged from 0.006 to 0.162 tons per day (tpd) for NO_<i>x</i>, 0.029 to 0.426 tpd for CO, and 67.9 to 371 tpd for CO₂. CH₄ and C₂H₆ emission rates from compressor stations ranged from 0.411 to 4.936 tpd and 0.023 to 0.062 tpd, respectively. Although limited in sample size, this study provides emission rate estimates for some processes in a newly developed natural gas resource and contributes valuable comparisons to other shale gas studies

Goetz_etal_2017_data

The zip file holds six tab delimited text files that contain 1 Hz mobile lab data and accompanying local background estimates from 2012 measurements in SW PA and NE PA and 2015 measurements in NE PA. See publication for more details. The provided local background data is derived from 20 minute 35th percentile smoothing. All time information is in military format. Date information is in mm/dd/yy. Concentration data is in units of ppbv. GPS data is in units of decimal degrees and in datum WGS84. Please contact authors if additional information is needed. All use of the provided data should be accompanied by the proper citations