Annual Average Basis Research Articles

Regional changes in nitrate loadings in the Upper Mississippi River Basin under predicted mid-century climate

The Upper Mississippi River Basin (UMRB) drains an area of 492,000 km2 primarily from five states in the central US. Alterations in climate variability and change will lead to changes in hydrologic behavior of the region with implications in the fate and transport of nutrient loadings. This impact assessment study evaluated the long-term changes in annual water yield and nitrogen loadings in the UMRB using the Soil and Water Assessment Tool (SWAT), with mid-century (2046–2065) climate change projections as predicted by the ensemble of ten general circulation models. Predicted precipitation change ranged from −1.6 to 6.3 % at the subwatershed level while the mean temperature was found to be more consistent over the entire basin with an average increase of 2.8 °C. The SWAT-predicted streamflow decreased by 5 % on an average annual basis at the watershed outlet (Grafton, Illinois) with significant monthly variation. Streamflow increased during the winter months of December, January, and February and decreased during the summer with up to a 41 % reduction in July. The nitrogen loading pattern was found to vary widely from a decrease of 3 kg/ha to an increase of 8 kg/ha at the subwatershed level, with an average increase of 1 kg/ha over the entire basin. Portions of the UMRB in Illinois are expected to shift toward adverse conditions for nitrogen loading (and thus greater potential for exporting), whereas portions of the UMRB in Iowa are expected to experience a decrease in nitrogen loads under predicted mid-century climatic conditions for the existing land and nutrient management.

Source apportionment and organic compound characterization of ambient ultrafine particulate matter (PM) in the Los Angeles Basin

In this study, quasi-UFP (PM0.25, dp < 0.25 μm) were collected for 24 h once per week from April 2008 to March 2009 at 10 different locations in the Los Angeles Basin. Samples were chemically analyzed and organic constituents of PM0.25 were grouped into polycyclic aromatic hydrocarbon (PAHs), hopanes and steranes, n-alkanes, and levoglucosan, with concentration levels ranging from 0.16 to 5.5, 0.09 to 2.2, 9.3 to 48, and 2.2 to 106.2 ng m−3 over all sites and seasons, respectively. A molecular marker-based chemical mass balance (MM-CMB) model was applied to estimate the relative contributions from the following primary sources: mobile sources (combined gasoline and diesel vehicles), wood smoke, natural gas combustion, vegetative detritus, and ship emissions. Secondary organic aerosol (SOA) tracers were not included in the model; however their contributions were estimated from non-biomass burning water soluble organic carbon (WSOCnb) and un-apportioned OC from MM-CMB model (“other OC”). High correlation (R2 = 0.8) between “other OC” and WSOCnb in summer suggests that “other OC” is highly impacted by SOA, however un-apportioned primary sources may contribute to “other OC” as well. Mobile sources were expectedly the major primary contributor to PM0.25, with seasonal average contributions of 31 ± 12% in summer and 57 ± 17% in winter. “Other organic matter” was the second largest contributor to PM0.25 in all seasons, across the basin, with substantially higher contribution during warmer spring and summer seasons (27%), while lowest during cold seasons (13%). Wood smoke was the third major contributor to PM0.25 in winter, whereas its contribution was lowest in summer. As expected, ship emissions displayed the highest contribution at the near-harbor HUD site, and their levels continually decreased as a function of distance from coast. Two other primary sources, vegetative detritus and natural gas combustion, collectively contributed to 1.3 ± 0.8% of PM0.25 on an annual average basis over all sites. Comparison of our results to PM2.5 OC apportionment, conducted at central LA, shows that contribution of mobile sources to PM0.25 OC is more than two times higher than PM2.5 (75% and 30%, respectively), while “other OC” contributed significantly higher to PM2.5 OC compared to PM0.25 (56% and 21%, respectively).

Changes in hydrology and streamflow as predicted by a modelling experiment forced with climate models

Changes in precipitation and temperature have direct effects on crop water use, water stress, crop yield, evapotranspiration, water nutrient dynamics and other indicators. This study, built on a modelling framework with the Soil and Watershed Assessment Tool (SWAT) model for the Raccoon River Watershed in central Iowa, a typical US Midwestern agricultural watershed, examines the watershed response to changes in meteorological inputs from an ensemble of ten global climate models under the A1B scenario. Changes in climate were directly applied to observations (the delta change method) assuming that the estimates of climate change are reliable even if the simulated current climate may be biased. The ensemble average for the mid-century (1946–1965) predicted 0.7% increase in daily precipitation (monthly variation from −11.3% to +19.5%) and 2.78 °C increase in average temperature over the entire watershed. These predictions were translated through a well-calibrated SWAT modelling setup into 22% decrease in snowfall, 16% decrease in surface runoff, 18% decrease in baseflow, 8% increase in evapotranspiration and 17% decrease in total water yield. The spatial impact at the subwatershed level revealed a wide variation (but no defined trend) with decrease in water yield that ranged from 10% to 23%. Flow near the watershed outlet (Van Meter, Iowa) is expected to decline by 17% on an average annual basis with the highest impact occurring during summer months with a maximum 39% reduction in August. Changes in climate were found to have a clear and significant impact signal of decreasing streamflow at the watershed outlet with far-reaching implication for drinking water supplies for the central Iowa communities. Copyright © 2013 John Wiley & Sons, Ltd.

Fuel-based fine particulate and black carbon emission factors from a railyard area in Atlanta

Railyards have the potential to influence local fine particulate matter (aerodynamic diameter ≤2.5 μm; PM2.5) concentrations through emissions from diesel locomotives and supporting activities. This is of concern in urban regions where railyards are in proximity to residential areas. Northwest of Atlanta, Georgia, Inman and Tilford railyards are located beside residential neighborhoods, industries, and schools. The PM2.5 concentrations near the railyards is the highest measured amongst the state-run monitoring sites (Georgia Environmental Protection Division, 2012; http://www.georgiaair.org/amp/report.php). The authors estimated fuel-based black carbon (BC) and PM2.5 emission factors for these railyards in order to help determine the impact of railyard activities on PM2.5 concentrations, and for assessing the potential benefits of replacing current locomotive engines with cleaner technologies. High-time-resolution measurements of BC, PM2.5, CO2, and wind speed and direction were made at two locations, north and south of the railyards. Emissions factors (i.e., the mass of BC or PM2.5 per gallon of fuel burned) were estimated by using the downwind/upwind difference in concentrations, wavelet analysis, and an event-based approach. By the authors’ estimates, diesel-electric engines used in the railyards have average emission factors of 2.8 ± 0.2 g of BC and 6.0 ± 0.5 g of PM2.5 per gallon of diesel fuel burned. A broader mix of railyard supporting activities appear to lead to average emission factors of 0.7 ± 0.03 g of BC and 1.5 ± 0.1 g of PM2.5 per gallon of diesel fuel burned. Railyard emissions appear to lead to average enhancements of approximately 1.7 ± 0.1 µg/m3 of PM2.5 and approximately 0.8 ± 0.01 µg/m3 of BC in neighboring areas on an annual average basis. Uncertainty not quantified in these results could arise mainly from variability in downwind/upwind differences, differences in emissions of the diverse zones within the railyards, and the influence of on-road mobile source emissions. Implications: In-use fuel-based black carbon and fine particulate emission factors for railyard activities were quantified by novel approaches using near-source high-time-resolution monitoring of ambient concentrations at two sites. Results can reduce the uncertainty in railyard emission inventories and the approach can be replicated and extended to assess trends and evaluate emission reduction alternatives. Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for information on dates of photographic surveillance of Inman yard, the algorithm for wavelet analysis, histograms and time series plots of Downwind/Upwind data, and boxplots of BC emission factors.

A New Reactor Concept for Efficient Solar-Thermochemical Fuel Production

We describe and analyze the efficiency of a new solar-thermochemical reactor concept, which employs a moving packed bed of reactive particles produce of H2 or CO from solar energy and H2O or CO2. The packed bed reactor incorporates several features essential to achieving high efficiency: spatial separation of pressures, temperature, and reaction products in the reactor; solid–solid sensible heat recovery between reaction steps; continuous on-sun operation; and direct solar illumination of the working material. Our efficiency analysis includes material thermodynamics and a detailed accounting of energy losses, and demonstrates that vacuum pumping, made possible by the innovative pressure separation approach in our reactor, has a decisive efficiency advantage over inert gas sweeping. We show that in a fully developed system, using CeO2 as a reactive material, the conversion efficiency of solar energy into H2 and CO at the design point can exceed 30%. The reactor operational flexibility makes it suitable for a wide range of operating conditions, allowing for high efficiency on an annual average basis. The mixture of H2 and CO, known as synthesis gas, is not only usable as a fuel but is also a universal starting point for the production of synthetic fuels compatible with the existing energy infrastructure. This would make it possible to replace petroleum derivatives used in transportation in the U.S., by using less than 0.7% of the U.S. land area, a roughly two orders of magnitude improvement over mature biofuel approaches. In addition, the packed bed reactor design is flexible and can be adapted to new, better performing reactive materials.

A Monitoring and Modeling Study to Investigate Regional Transport and Characteristics of PM2.5 Pollution

In this study, the regional transport and characteristics of PM2.5 pollution were examined through a case study in Beijing, China. The results from an intensive monitoring program indicate that the inorganic particles (sulfate, nitrate, and ammonium), organic carbons, and the elements accounted for 35.5, 24.2, and 15.3% of the total PM2.5 on an annual average basis, respectively. The proportions of such PM2.5 components also showed clear seasonal variations. An integrated MM5-CMAQ modeling system was then developed to examine the regional transport of PM2.5 and its components in Beijing within four typical months of 2010. The results indicate that the annual average total trans-boundary contribution ratio (TBCR) is 42.2, 46.3, 77.4, and 61.6% for the concentrations of PM2.5, sulfate, nitrate, and ammonium, respectively. A logarithmic relationship was found between the total TBCR and the PM2.5 concentrations in Beijing for different seasons. Further investigations showed that trans-boundary transport played a major role in Beijing’s PM2.5 concentrations during the period of high pollution levels, with an annual average TBCR of 54.6%. As a result, the control of PM2.5 pollution in Beijing needs effective cooperation between Beijing and its surrounding regions, especially during periods of heavy pollution.

How does afforestation affect the hydrology of a blanket peatland? A modelling study

AbstractOver the last century, afforestation in Ireland has increased from 1% of the land area to 10%, with most plantations on upland drained blanket peatlands. This land use change is considered to have altered the hydrological response and water balance of upland catchments with implications for water resources. Because of the difficulty of observing these long‐term changes in the field, the aim of this study was to utilize a hydrological model to simulate the rainfall runoff processes of an existing pristine blanket peatland and then to simulate the hydrology of the peatland if it were drained and afforested. The hydrological rainfall runoff model (GEOtop) was calibrated and validated for an existing small (76 ha) pristine blanket peatland in the southwest of Ireland for the 2‐year period, 2007–2008. The current hydrological response of the pristine blanket peatland catchment with regard to streamflow and water table (WT) levels was captured well in the simulations. Two land use change scenarios of afforestation were also examined, (A) a young 10‐year‐old and (B) a semi‐mature 15‐year‐old Sitka Spruce forest. Scenario A produced similar streamflow dynamics to the pristine peatland, whereas total annual streamflow from Scenario B was 20% lower. For Scenarios A and B, on an annual average basis, the WT was drawn down by 16 and 20 cm below that observed in the pristine peatland, respectively. The maximum WT draw down in Scenario B was 61 cm and occurred in the summer months, resulting in a significant decrease in summer streamflow. Occasionally in the winter (following rainfall), the WT for Scenario B was just 2 cm lower than the pristine peatland, which when coupled with the drainage networks associated with afforestation led to higher peak streamflows. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Nutrient cycling in Casuarina (Casuarina equisetifolia) based agroforestry system

The present report gives an account of the results of research carried out on litter production, accumulation and nutrient return through rainfall, stem flow, throughfall and interception to soil litter fall, under Casuarina-Black Gram Agroforestry Models (age 4 years, density 650 trees/ha). It was found that of the total rainfall (497.9 mm) 1.2% was recorded as stem flow and 80% as throughfall while the interception accounted for 19 %. It is found that on an average annual basis, of the total uptake of various nutrients was retained in the non-photosynthetic biomass and the rest returned to soil. These results show that among the nutrients, maximum annual retention was accounted for potassium while, the minimum for nitrogen. This paper deals the nutrient accumulation in standing crop, nutrient concentration and return, rainfall interception, nutrient concentration in rain wash, nutrient return through rain wash and Nutrient retained, returned and uptake (kg/ha/yr) in Casuarina under Agroforestry System in detail.

Economic and employment implications of a carbon market for industrial plantation forestry

Industrial plantation forestry has the potential to make a significant contribution to carbon sequestration, subject to eligibility in carbon markets and other accounting rules. We considered the sequestration potential and economic viability of industrial forestry in four case studies across Australia: softwood sawlog production in regions of high and low rainfall, and hardwood pulpwood production in regions of high and medium rainfall. We considered both the establishment of new plantations on cleared agricultural land and increases in rotation length of existing forests to increase carbon sequestration. Our study found that establishment of new plantations in cleared agricultural land is generally not economically viable with current costs of establishment (including land value) and returns for wood products. On average, for scenarios of hardwoods and softwoods, a payment for carbon sequestration of about $10 and $30 per tonne of CO2-e is required, respectively, for expansion of the estate to be economically viable (AU$2011). With the exception of softwoods grown in high rainfall, even higher payments for carbon sequestration are required to make increasing rotation lengths of existing forests economically viable, with a break even carbon price for hardwoods and softwoods of about $10 and $40 per tonne of CO2-e, respectively. Although crediting carbon stored in soil and wood products can significantly increase economic viability in some regions, more work is required to verify these predictions and to develop cost-effective measurement methodologies. In contrast, our analysis showed that there was little impact on economic viability of debiting emissions associated with forestry operations and harvesting, as these are a small proportion of the overall carbon balance. On an average annual basis, employment in industrial plantations was found to be comparable to alternative land uses, suggesting forestry does not result in a net loss of regional jobs. We conclude that there is considerable sequestration potential through industrial plantation management if the price on carbon is sufficiently high (e.g. $50 per tonne of CO2-e) and there are no limiting institutional factors (e.g. policies that restrict expansion of plantations onto agricultural land).

Les banques américaines après la crise financière?: adaptations sous contraintes

Les banques américaines avaient abordé le xxie siècle avec des taux de rentabilité financière élevés, mais l’éclatement de la crise des subprimes à l’été 2007 a, en moyenne annuelle, réduit ces taux de moitié. Moins de quatre ans après le paroxysme de la crise financière, les banques américaines ont renoué avec les profits plus rapidement qu’escompté, surtout au regard de la profondeur de la crise. Le redressement a toutefois largement résulté de la décrue du coût du risque, par nature non reproductible, tandis que les revenus devraient être durablement pénalisés par le contexte de désendettement du secteur non financier, une configuration des taux moins favorable et un cadre réglementaire renforcé. Profondément marqué du sceau de la crise financière, le nouveau contexte économique, financier et réglementaire qui se dessine pourrait peser durablement sur les performances financières des banques américaines et redéfinir, au moins partiellement, les contours des modèles bancaires qui coexistaient avant la crise.Classification JEL?: G01, G21, G28.

Sources and seasonality of atmospheric methanol based on tall tower measurements in the US Upper Midwest

Abstract. We present over one year (January 2010–February 2011) of continuous atmospheric methanol measurements from the University of Minnesota tall tower Trace Gas Observatory (KCMP tall tower; 244 m a.g.l.), and interpret the dataset in terms of constraints on regional methanol sources and seasonality. The seasonal cycle of methanol concentrations observed at the KCMP tall tower is generally similar to that simulated by a global 3-D chemical transport model (GEOS-Chem, driven with MEGANv2.0 biogenic emissions) except the seasonal peak occurs ~1 month earlier in the observations, apparently reflecting a model underestimate of emission rates for younger versus older leaves. Based on a source tracer approach, which we evaluate using GEOS-Chem and with multiple tracers, we estimate that anthropogenic emissions account for approximately 40% of ambient methanol abundance during winter and 10% during summer. During daytime in summer, methanol concentrations increase exponentially with temperature, reflecting the temperature sensitivity of the biogenic source, and the observed temperature dependence is statistically consistent with that in the model. Nevertheless, summertime concentrations are underestimated by on average 35% in the model for this region. The seasonal importance of methanol as a source of formaldehyde (HCHO) and carbon monoxide (CO) is highest in spring through early summer, when biogenic methanol emissions are high but isoprene emissions are still relatively low. During that time observed methanol concentrations account for on average 20% of the total CO and HCHO production rates as simulated by GEOS-Chem, compared to 12% later in the summer and 12% on an annual average basis. The biased seasonality in the model means that the photochemical role for methanol early in the growing season is presently underestimated.

Development of a coupled soil erosion and large‐scale hydrology modeling system

Soil erosion models are usually limited in their application to the field scale; however, the management of land resources requires information at the regional scale. Large‐scale physically based land surface schemes (LSS) provide estimates of regional scale hydrologic processes that contribute to erosion. If scaling issues are adequately addressed, coupling an LSS to a physically based erosion model can provide a tool to study the regional impact of soil erosion. A coupling scheme was developed using the Variable Infiltration Capacity (VIC) model to produce hydrologic inputs for the stand‐alone Water Erosion Prediction Project‐Hillslope Erosion (WEPP‐HE) program, accounting for both temporal and spatial scaling issues. Precipitation events were disaggregated from daily to hourly and used with the VIC model to generate hydrologic fluxes. Slope profiles were downscaled from 30 arc second to 30 m hillslopes. Additionally, soil texture and erodibility were adjusted with simplified assumptions based on the full WEPP model. Soil erosion at the large scale was represented on a VIC model grid cell basis by applying WEPP‐HE to subsamples of 30 m hillslopes. On an average annual basis, results showed that the coupled model was comparable with full WEPP model predictions. On an event basis, the coupled model system captured more small erosion events, with erodibility adjustments of the same magnitude as from the full WEPP model simulations. Differences in results can be attributed to discrepancies in hydrologic data calculations and simplified assumptions in vegetation and soil erodibility. Overall, the coupled model demonstrated the feasibility of erosion prediction for large river basins.

Source characterization for aerosol constituents and changing roles of calcium and ammonium aerosols in the neutralization of aerosol acidity at a semi-urban site in SW India

Atmospheric aerosols were collected at a semi-urban site in Pune city, located in the southwestern part of India, during the year 2007–08 covering different seasons. Anthropogenically derived particles (Non seasalt and non crustal fractions of SO4, Cl, K, Ca and Mg together with NO3, NH4, Cu, Zn and black carbon) contributed about 73% of the total measured TSP. Natural sources like sea (16%) and soil (11%) contributed about 27% to the total measured composition of TSP on annual basis. Surprisingly, Ca which is generally observed from crustal source, showed equal contribution from crustal and anthropogenic sources and was the major neutralizer of aerosol acidity in summer and monsoon seasons. NH4 was the most abundant component on annual average basis among the measured chemical components and also it was the leading neutralizer of aerosol acidity during post-monsoon and winter seasons. Aerosols showed alkaline nature (mean annual pH 6.51 and Neutralization Potential/Acidic Potential ratio 1.45) due to the neutralizing effect of Ca and NH4.

Study of high and low amplitude wave trains of cosmic ray diurnal variation during solar cycle 23

A detailed study has been conducted on the long-term changes in the diurnal variation of cosmic rays in terms of high and low amplitude wave trains event (HAEs/LAEs) during the period 1996–2008 (solar cycle 23), using the neutron monitor data from Kiel neutron monitoring station. As such, 17 HAE and 48 LAE cases have been detected and analyzed. These HAEs appear quite dominantly during the declining phase as well as near the maximum of the solar activity cycle 23. In contrast, the low amplitude events (LAEs) are inversely correlated with solar activity cycle. In fact, LAEs appear quite dominantly during the minimum phase of the solar activity. When we compare our results for diurnal phase with that observed on an annual average basis, we notice no significant diurnal phase shift for HAEs as well as for LAEs. Moreover, we find that the high-speed solar wind streams (HSSWS) do not play any significant role in causing these variations. These results are discussed on the basis of that observed in earlier cycles.

A modelling assessment of contaminant distributions in the Severn Estuary

The regulatory requirements imposed by the Habitats Directive (EU 93/43/EEC) require the Environment Agency for England and Wales (EA) to review consented discharges and determine whether they are compliant with Environmental Quality Standards (EQS). Since the EQS are annual averages, model predictions, and sample comparisons, should be made on an annual average basis. Advection and dispersion of metal contaminants in the Severn Estuary were computed using a coupled 1-D and 2-D hydrodynamic-water quality model. The external inputs of dissolved copper, arsenic, mercury and chromium to the model were from 66 industrial discharges and sewage treatment works and 30 rivers. The annual average predicted concentrations were compared with the annual average dissolved metal concentrations from the 2004 and 2005 monitoring programme, and any discrepancy used to identify the role of additional processes, mainly involving the sediments. This ability to separate anthropogenic inputs from internal estuarine processes contributes to a better understanding of the functioning of the estuary and hence an improved management capability. The paper discusses the approach in designing scenarios and characterising uncertainty, when decision-making in the regulatory context.

Partitioning phosphorus concentrations and loads in tributaries of a recovering urban lake*

The partitioning of phosphorus (P) loading to culturally eutrophic lakes according to sources is fundamental information to guide rehabilitation programs and support mathematical models. Patterns of concentrations and loading rates of forms of P are documented for the major tributaries of Onondaga Lake, New York, United States, an urban lake that has recently demonstrated marked recovery from extreme cultural eutrophy as a result of decreased P loading from a domestic wastewater treatment plant (WWTP). This analysis is based on long-term (19 yr) biweekly monitoring of total, dissolved, and soluble reactive forms of P at the mouths of the three largest tributaries, and shorter-term higher frequency monitoring of one of the streams at two sites to resolve rural versus urban contributions. Signatures of anthropogenic sources were identified, including: (1) combined sewer overflows, (2) leaky sewers or other dry weather discharges, and (3) hydrogeologic sediment sources. On an annual average basis, the prevailing tributary and WWTP contributions to the total P load are approximately 70 and 30%, respectively. However, in terms of effective P loading, that which can be used to support primary production during the critical summer months, the tributaries contributed substantially less (∼35%) of the P load. Under the prevailing WWTP loading rate, reductions in tributary loading from aggressive tributary loading management efforts (e.g., 20–30% decrease) would not be expected to yield conspicuous improvements in related features of lake water quality. However, noteworthy improvements are a reasonable expectation from such tributary management efforts following the mandated further reductions in WWTP loading.

In with the New A Look at the Metro Wastewater Reclamation District's (MWRD) GIS Biosolids Land Application Operation

In with the New A Look at the Metro Wastewater Reclamation District's (MWRD) GIS Biosolids Land Application OperationThe Metro Wastewater Reclamation District (District) in Denver, Colorado is the largest wastewater treatment facility between the Mississippi river and the west coast. The District treats approximately 130 million gallons of wastewater and produces an average of 80 dry tons of Class B biosolids per day. On an annual average basis, 88 percent of the biosolids are transported from the Robert W. Hite...Author(s)Arlisa L. MichaelSourceProceedings of the Water Environment FederationSubjectSession 17 - Land ApplicationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2009ISSN1938-6478SICI1938-6478(20090101)2009:3L.1112;1-DOI10.2175/193864709793846187Volume / Issue2009 / 3Content sourceResiduals and Biosolids ConferenceFirst / last page(s)1112 - 1117Copyright2009Word count275Subject keywordsGISFarm WorksBiosolids

Developing a decision support tool for China's re-vegetation program: Simulating regional impacts of afforestation on average annual streamflow in the Loess Plateau

China is facing increased environmental pressures as its economy rapidly develops, with shortages of water potentially limiting development—especially in its dryer north and west. The highly erodible Loess Plateau in the Yellow River Basin is the main source of high sediment loads resulting in poor water quality. Engineering and re-vegetation measures have been (and are being) widely implemented to reduce these environmental problems, but it has since been found that re-vegetation activities result in a decrease of streamflow. Given that water resources are currently over allocated in the Yellow River Basin (as seen by the river increasingly not reaching the sea), the external hydrological impacts from current and planned re-vegetation activities need to be taken into account by a wide range of natural resources managers and policy makers. To increase the awareness of the hydrology-landuse change implications in the region, a decision support tool called Re-Vegetation Impacts on Hydrology (ReVegIH) has been developed. To maximize use of the tool, the design of ReVegIH has been participatory with the final design of the functionality actively taking account of user requirements and needs. ReVegIH provides a means for users to: (1) determine where priority (and target) re-vegetation activities should be undertaken; (2) ascertain what species are suitable for a specific location; (3) simulate the related hydrological impact on an average annual basis. The spatial resolution of the first two functions is provided at 100 m, while the third is at the catchment (or county) level for the 113,000 km 2 study site, called the Coarse Sandy Hilly Catchment, which drains the main south flowing branch of the Yellow River. ReVegIH assesses afforestation impacts on average annual streamflow via application of an aerial-weighted evapotranspiration model operating at steady-state forced by long-term (21-year) annual average meteorological data and landuse scenarios. ReVegIH does not consider the changes in annual streamflow following observed 21-year trends of annual precipitation and pan evaporation data, nor as a function of time since afforestation, and the ability to simulate the hydrological impact due to establishing plantations in different areas in the landscape through time is not included.

Coarse particle speciation at selected locations in the rural continental United States

A few short-term special studies at National Parks have shown that coarse mass (CM) (2.5– 10 μ m ) may not be just crustal minerals but may consist of a substantial amount ( ≈ 40 –50%) of carbonaceous material and inorganic salts such as calcium nitrate and sodium nitrate. To more fully investigate the composition of coarse particles, a program of coarse particle sampling and speciation analysis at nine of the Interagency Monitoring of Protected Visual Environments (IMPROVE) sites was initiated 19 March 2003 and operated through the year 2004. Only the data for 2004 are reported here. Sites were selected to be representative of the continental United States and were operated according to IMPROVE protocol analytical procedures. Crustal minerals (soil) are the single largest contributor to CM at all but one monitoring location. The average fractional contributions range from a high of 76% at Grand Canyon National Park to a low of 34% at Mount Rainier National Park. The second largest contributor to CM is organic mass, which on an average annual fractional basis is highest at Mount Rainier at 59%. At Great Smoky Mountains National Park, organic mass contributes 40% on average, while at four sites organic mass concentrations contribute between 20% and 30% of the CM. Nitrates are on average the third largest contributor to CM concentrations. The highest fractional contributions of nitrates to CM are at Brigantine National Wildlife Refuge, Great Smoky Mountains, and San Gorgonio wilderness area at 10–12%. Sulfates contribute less than about 5% at all sites.

Source apportionment of airborne particulate matter using organic compounds as tracers

A chemical mass balance receptor model based on organic compounds has been developed that relates source contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.