PM2.5 source apportionment with organic markers in the Southeastern Aerosol Research and Characterization (SEARCH) study

Positive matrix factorization (PMF) and effective variance (EV) solutions to the chemical mass balance (CMB) were applied to PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) mass and chemically speciated measurements for samples taken from 2008 to 2010 at the Atlanta, Georgia, and Birmingham, Alabama, sites. Commonly measured PM_2.5 mass, elemental, ionic, and thermal carbon fraction concentrations were supplemented with detailed nonpolar organic speciation by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). Source contribution estimates were calculated for motor vehicle exhaust, biomass burning, cooking, coal-fired power plants, road dust, vegetative detritus, and secondary sulfates and nitrates for Atlanta. Similar sources were found for Birmingham, with the addition of an industrial source and the separation of biomass burning into open burning and residential wood combustion. EV-CMB results based on conventional species were qualitatively similar to those estimated by PMF-CMB. Secondary ammonium sulfate was the largest contributor, accounting for 27–38% of PM_2.5, followed by biomass burning (21–24%) and motor vehicle exhaust (9–24%) at both sites, with 4–6% of PM_2.5 attributed to coal-fired power plants by EV-CMB. Including organic compounds in the EV-CMB reduced the motor vehicle exhaust and biomass burning contributions at both sites, with a 13–23% deficit for PM_2.5 mass. The PMF-CMB solution showed mixing of sources within the derived factors, both with and without the addition of speciated organics, as is often the case with complex source mixtures such as those at these urban-scale sites. The nonpolar TD-GC/MS compounds can be obtained from existing filter samples and are a useful complement to the elements, ions, and carbon fractions. However, they should be supplemented with other methods, such as TD-GC/MS on derivitized samples, to obtain a wider range of polar compounds such as sterols, sugars, and organic acids. The PMF and EV solutions to the CMB equations are complementary to, rather than replacements for, each other, as comparisons of their results reveal uncertainties that are not otherwise evident.

Implications:?Organic markers can be measured on currently acquired PM_2.5 filter samples by thermal methods. These markers can complement element, ion, and carbon fraction measurements from long-term speciation networks. Applying the positive matrix factorization and effective variance solutions for the chemical mass balance equations provides useful information on the accuracy of the source contribution estimates. Nonpolar compounds need to be complemented with polar compounds to better apportion cooking and secondary organic aerosol contributors.     

Fingerprinting of High Boiling Hydrocarbon Fuels,Asphalts and Lubricants

Fingerprinting of hydrocarbon products requires high resolution differentiation of individual hydrocarbon compounds in any mixture. This requires the applications of various measuring techniques. In this paper, we have chosen the heavy hydrocarbons in fuels, lubricants and paving material as examples to discuss the methods for chemical characterization and differentiation. In the category most frequently termed "semi-volatile hydrocarbons" with boiling points from about 500°F to 1200°F or higher, there are several families of hydrocarbons, both natural and refined that are not easily distinguished by conventional EPA tests. Among the groups which we will use as examples are asphalts, hydraulic fluid, transmission oil, motor lubricating oils, heating oils, crude oil and coal. These hydrocarbon families are best studied using combined gas chromatography-mass spectrometry in full scan mode and characterizing various homologous series of hydrocarbons at known fragment ions. The hydrocarbon series providing the best information are: (1) N -alkanes; (2) iso-alkanes; (3) steranes; (4) terpanes; (5) polynuclear aromatic hydrocarbons; (6) aromatic steranes; and (7) specific polycyclic compounds.     

Simulating Land-Cover Change in Montane Mainland Southeast Asia

We used the conversion of land use and its effects (CLUE-s) model to simulate scenarios of land-cover change in Montane mainland southeast Asia (MMSEA), a region in the midst of transformation due to rapid intensification of agriculture and expansion of regional trade markets. Simulated changes affected approximately 10 % of the MMSEA landscape between 2001 and 2025 and 16 % between 2001 and 2050. Roughly 9 % of the current vegetation, which consists of native species of trees, shrubs, and grasses, is projected to be replaced by tree plantations, tea, and other evergreen shrubs during the 50 years period. Importantly, 4 % of this transition is expected to be due to the expansion of rubber (Hevea brasiliensis), a tree plantation crop that may have important implications for local-to-regional scale hydrology because of its potentially high water consumption in the dry season.     

Reforestation Strategies Amid Social Instability: Lessons from Afghanistan

Foreign and domestic government agencies and other international organizations pursue reforestation programs in rural upper watershed areas of Afghanistan over the past decade to alleviate poverty, combat the insurgency and rehabilitate a depleted forest resource base. Popular programs incorporate cash-for-work to conduct hillside terracing, check dam construction and tree-planting for nut production, fuel wood, timber, dune stabilization, and erosion abatement. Programmatic approaches have varied as a function of accessibility, security and local objectives. Uncertain land tenure and use rights, weak local environmental management capacity, and a focus on agricultural production to meet immediate needs limit interest, nationally and locally. Unreliable security, a lack of high quality tree planting stock, limited technical knowledge and coordination among government agencies, and poor security hamper program expansion. Reforestation success would be most likely where these issues are least acute. The Afghan government should focus on supporting community based natural resource management, developing and disseminating improved conservation tree nursery strategies, and promoting watershed management schemes that incorporate forestry, range management and agronomic production. Reforestation practitioners could benefit from the human and material resources now present as part of the international war effort. Successes and failures encountered in Afghanistan should be considered in order to address similar problems in insecure regions elsewhere when reforestation may help reverse environmental degradation and contribute to broader social stabilization efforts.     

Low-disturbance manure incorporation effects on ammonia and nitrate loss

Low-disturbance manure application methods can provide the benefits of manure incorporation, including reducing ammonia (NH3) emissions, in production systems where tillage is not possible. However, incorporation can exacerbate nitrate (NO3?) leaching. We sought to assess the trade-offs in NH3 and NO3? losses caused by alternative manure application methods. Dairy slurry (2006-2007) and liquid swine manure (2008-2009) were applied to no-till corn by (i) shallow (<10 cm) disk injection, (ii) surface banding with soil aeration, (iii) broadcasting, and (iv) broadcasting with tillage incorporation. Ammonia emissions were monitored for 72 h after application using ventilated chambers and passive diffusion samplers, and NO3? leaching to 80 cm was monitored with buried column lysimeters. The greatest NH3 emissions occurred with broadcasting (35-63 kg NH3-N ha?), and the lowest emissions were from unamended soil (<1 kg NH-N ha?1). Injection decreased NH-N emissions by 91 to 99% compared with broadcasting and resulted in lower emissions than tillage incorporation 1 h after broadcasting. Ammonia-nitrogen emissions from banding manure with aeration were inconsistent between years, averaging 0 to 71% that of broadcasting. Annual NO3? leaching losses were small (<25 kg NO3-N ha?1) and similar between treatments, except for the first winter when NO3? leaching was fivefold greater with injection. Because NO3? leaching with injection was substantially lower over subsequent seasons, we hypothesize that the elevated losses during the first winter were through preferential flow paths inadvertently created during lysimeter installation. Overall, shallow disk injection yielded the lowest NH3 emissions without consistently increasing NO3? leaching, whereas manure banding with soil aeration conserved inconsistent amounts of N.     

Environmental Condition Assessment of US Military Installations Using GIS Based Spatial Multi-Criteria Decision Analysis

Environment functions in various aspects including soil and water conservation, biodiversity and habitats, and landscape aesthetics. Comprehensive assessment of environmental condition is thus a great challenge. The issues include how to assess individual environmental components such as landscape aesthetics and integrate them into an indicator that can comprehensively quantify environmental condition. In this study, a geographic information systems based spatial multi-criteria decision analysis was used to integrate environmental variables and create the indicator. This approach was applied to Fort Riley Military installation in which land condition and its dynamics due to military training activities were assessed. The indicator was derived by integrating soil erosion, water quality, landscape fragmentation, landscape aesthetics, and noise based on the weights from the experts by assessing and ranking the environmental variables in terms of their importance. The results showed that landscape level indicator well quantified the overall environmental condition and its dynamics, while the indicator at level of patch that is defined as a homogeneous area that is different from its surroundings detailed the spatiotemporal variability of environmental condition. The environmental condition was mostly determined by soil erosion, then landscape fragmentation, water quality, landscape aesthetics, and noise. Overall, environmental condition at both landscape and patch levels greatly varied depending on the degree of ground and canopy disturbance and their spatial patterns due to military training activities and being related to slope. It was also determined the environment itself could be recovered quickly once military training was halt or reduced. Thus, this study provided an effective tool for the army land managers to monitor environmental dynamics and plan military training activities. Its limitation lies at that the obtained values of the indicator vary and are subjective to the experts' knowledge and experience. Thus, further advancing this approach is needed by developing a scientific method to derive the weights of environmental variables.     

Monitoring of Vegetation Impact Due to Trampling on Cadillac Mountain Summit Using High Spatial Resolution Remote Sensing Data Sets

Cadillac Mountain—the highest peak along the eastern seaboard of the United States—is a major tourist destination in Acadia National Park, Maine. Managing vegetation impact due to trampling on the Cadillac Mountain summit is extremely challenging because of the large number of visitors and the general open nature of landscape in this fragile subalpine environmental setting. Since 2000, more intensive management strategies—based on placing physical barriers and educational messages for visitors—have been employed to protect threatened vegetation, decrease vegetation impact, and enhance vegetation recovery in the vicinity of the summit loop trail. The primary purpose of this study was to evaluate the effect of the management strategies employed. For this purpose, vegetation cover changes between 2001 and 2007 were detected using multispectral high spatial resolution remote sensing data sets. A normalized difference vegetation index was employed to identify the rates of increase and decrease in the vegetation areas. Three buffering distances (30, 60, and 90?m) from the edges of the trail were used to define multiple spatial extents of the site, and the same spatial extents were employed at a nearby control site that had no visitors. No significant differences were detected between the mean rates of vegetation increase and decrease at the experimental site compared with a nearby control site in the case of a small spatial scale (≤30?m) comparison (in all cases P?>?0.05). However, in the medium (≤60?m) and large (≤90?m) spatial scales, the rates of increased vegetation were significantly greater and rates of decreased vegetation significantly lower at the experimental site compared with the control site (in all cases P?<?0.001). Research implications are explored that relate to the spatial extent of the radial patterns of impact of trampling on vegetation at the site level. Management implications are explored in terms of the spatial strategies used to decrease the impact of trampling on vegetation.     

Can Volunteers Collect Data that are Comparable to Professional Scientists? A Study of Variables Used in Monitoring the Outcomes of Ecosystem Rehabilitation

Having volunteers collect data can be a cost-effective strategy to complement or replace those collected by scientists. The quality of these data is essential where field-collected data are used to monitor progress against predetermined standards because they provide decision makers with confidence that choices they make will not cause more harm than good. The integrity of volunteer-collected data is often doubted. In this study, we made estimates of seven vegetation attributes and a composite measure of six of those seven, to simulate benchmark values. These attributes are routinely recorded as part of rehabilitation projects in Australia and elsewhere in the world. The degree of agreement in data collected by volunteers was compared with those recorded by professional scientists. Combined results showed that scientists collected data that was in closer agreement with benchmarks than those of volunteers, but when data collected by individuals were analyzed, some volunteers collected data that were in similar or closer agreement, than scientists. Both groups’ estimates were in closer agreement for particular attributes than others, suggesting that some attributes are more difficult to estimate than others, or that some are more subjective than others. There are a number of ways in which higher degrees of agreement could be achieved and introducing these will no doubt result in better, more effective programs, to monitor rehabilitation activities. Alternatively, less subjective measures should be sought when developing monitoring protocols. Quality assurance should be part of developing monitoring methods and explicitly budgeted for in project planning to prevent misleading declarations of rehabilitation success.     

Mixed-Grass Prairie Canopy Structure and Spectral Reflectance Vary with Topographic Position

Managers of the nearly 0.5 million ha of public lands in North and South Dakota, USA rely heavily on manual measurements of canopy height in autumn to ensure conservation of grassland structure for wildlife and forage for livestock. However, more comprehensive assessment of vegetation structure could be achieved for mixed-grass prairie by integrating field survey, topographic position (summit, mid and toeslope) and spectral reflectance data. Thus, we examined the variation of mixed-grass prairie structural attributes (canopy leaf area, standing crop mass, canopy height, nitrogen, and water content) and spectral vegetation indices (VIs) with variation in topographic position at the Grand River National Grassland (GRNG), South Dakota. We conducted the study on a 36,000-ha herbaceous area within the GRNG, where randomly selected plots (1?km² in size) were geolocated and included summit, mid and toeslope positions. We tested for effects of topographic position on measured vegetation attributes and VIs calculated from Landsat TM and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data collected in July 2010. Leaf area, standing crop mass, canopy height, nitrogen, and water content were lower at summits than at toeslopes. The simple ratio of Landsat Band 7/Band 1 (SR71) was the VI most highly correlated with canopy standing crop and height at plot and landscape scales. Results suggest field and remote sensing-based grassland assessment techniques could more comprehensively target low structure areas at minimal expense by layering modeled imagery over a landscape stratified into topographic position groups.