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• 1. [Article] Divergent trends in ecosystem services under different climate-management futures in a fire-prone forest landscape

  While ecosystem services and climate change are often examined independently, quantitative assessments integrating these fields are needed to inform future land management decisions. Using climate-informed ...

  Citation × Citation Citation Abstract Copy Title: Divergent trends in ecosystem services under different climate-management futures in a fire-prone forest landscape Author: Halofsky, Joshua S., Halofsky, Jessica E., Hemstrom, Miles A., Morzillo, Anita T., Zhou, Xiaoping, Donato, Daniel C. Year: 2017 While ecosystem services and climate change are often examined independently, quantitative assessments integrating these fields are needed to inform future land management decisions. Using climate-informed state-and-transition simulations, we examined projected trends and trade-offs for a suite of ecosystem services under four climate change scenarios and two management scenarios (active management emphasizing fuel treatments and no management other than fire suppression) in a fire-prone landscape of dry and moist mixed-conifer forests in central Oregon, USA. Focal ecosystem services included fire potential (regulating service), timber volume (provisioning service), and potential wildlife habitat (supporting service). Projections without climate change suggested active management in dry mixed-conifer forests would create more open forest structures, reduce crown fire potential, and maintain timber stocks, while in moist mixed-conifer forests, active management would reduce crown fire potential but at the expense of timber stocks. When climate change was considered, however, trends in most ecosystem services changed substantially, with large increases in wildfire area predominating broad-scale trends in outputs, regardless of management approach (e.g., strong declines in timber stocks and habitat for closed-forest wildlife species). Active management still had an influence under a changing climate, but as a moderator of the strong climate-driven trends rather than being a principal driver of ecosystem service outputs. These results suggest projections of future ecosystem services that do not consider climate change may result in unrealistic expectations of benefits. Title: Divergent trends in ecosystem services under different climate-management futures in a fire-prone forest landscape Author: Halofsky, Joshua S., Halofsky, Jessica E., Hemstrom, Miles A., Morzillo, Anita T., Zhou, Xiaoping, Donato, Daniel C. Year: 2017 While ecosystem services and climate change are often examined independently, quantitative assessments integrating these fields are needed to inform future land management decisions. Using climate-informed state-and-transition simulations, we examined projected trends and trade-offs for a suite of ecosystem services under four climate change scenarios and two management scenarios (active management emphasizing fuel treatments and no management other than fire suppression) in a fire-prone landscape of dry and moist mixed-conifer forests in central Oregon, USA. Focal ecosystem services included fire potential (regulating service), timber volume (provisioning service), and potential wildlife habitat (supporting service). Projections without climate change suggested active management in dry mixed-conifer forests would create more open forest structures, reduce crown fire potential, and maintain timber stocks, while in moist mixed-conifer forests, active management would reduce crown fire potential but at the expense of timber stocks. When climate change was considered, however, trends in most ecosystem services changed substantially, with large increases in wildfire area predominating broad-scale trends in outputs, regardless of management approach (e.g., strong declines in timber stocks and habitat for closed-forest wildlife species). Active management still had an influence under a changing climate, but as a moderator of the strong climate-driven trends rather than being a principal driver of ecosystem service outputs. These results suggest projections of future ecosystem services that do not consider climate change may result in unrealistic expectations of benefits. Close

• 2. [Article] A 30-Year Record of the Isotopic Composition of Atmospheric Methane

  Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year ...

  Citation × Citation Citation Abstract Copy Title: A 30-Year Record of the Isotopic Composition of Atmospheric Methane Author: Teama, Doaa Galal Mohammed Year: 2013 Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year time horizon). Its atmospheric concentration has more than doubled from the preindustrial era due to anthropogenic activities such as rice cultivation, biomass burning, and fossil fuel production. However, the rate of increase of atmospheric CH4 (or the growth rate) slowed from 1980 until present. The main reason for this trend is a slowdown in the trend of CH4 sources. Measuring stable isotopes of atmospheric CH4 can constrain changes of CH4 sources. The main goal of this work is to interpret the CH4 trend from 1978-2010 in terms of its sources using measurements of CH4 mixing ratio and its isotopes. The current work presents the measurements and analysis of CH4 and its isotopes (δ13C and δD) of four air archive sample sets collected by the Oregon Graduate Institute (OGI). CH4 isotope ratios (δ13C and δD) were measured by a continuous flow isotope ratio mass spectrometer technique developed at PSU. The first set is for Cape Meares, Oregon which is the oldest and longest set and spans 1977-1999. The integrity of this sample set was evaluated by comparing between our measured CH4 mixing ratio values with those measured values by OGI and was found to be stable. Resulting CH4 seasonal cycle was evaluated from the Cape Meares data. The CH4 seasonal cycle shows a broad maximum during October-April and a minimum between July and August. The seasonal cycles of δ13C and δD have maximum values in May for δ13C and in July for δD and minimum values between September-October for δ13C and in October for δD. These results indicate a CH4 source that is more enriched January-May (e.g. biomass burning) and a source that is more depleted August-October (e.g. microbial). In addition to Cape Meares, air archive sets were analyzed from: South Pole (SPO), Samoa (SMO), Mauna Loa (MLO) 1992-1996. The presented δD measurements are unique measured values during these time periods at these stations. To obtain the long-term in isotopic CH4 from 1978-2010, other datasets of Northern Hemisphere mid-latitude sites are included with Cape Meares. These sites are Olympic Peninsula, Washington; Montaña de Oro, California; and Niwot Ridge, Colorado. The seasonal cycles of CH4 and its isotopes from the composite dataset have the same phase and amplitudes as the Cape Meares site. CH4 growth rate shows a decrease over time 1978-2010 with three main spikes in 1992, 1998, and 2003 consistent with the literature from the global trend. CH4 lifetime is estimated to 9.7 yrs. The δ13C trend in the composite data shows a slow increase from 1978-1987, a more rapid rate of change 1987-2005, and a gradual depletion during 2005-2010. The δD trend in the composite data shows a gradual increase during 1978-2001 and decrease from 2001-2005. From these results, the global CH4 emissions are estimated and show a leveling off sources 1982-2010 with two large peak anomalies in 1998 and 2003. The global average δ13C and δD of CH4 sources are estimated from measured values. The results of these calculations indicate that there is more than one source which controls the decrease in the global CH4 trend. From 1982-2001, δ13C and δD of CH4 sources becomes more depleted due to a decrease in fossil and/or biomass burning sources relative to microbial sources. From 2005-2010, δ13C of CH4 sources returns to its 1981 value. There are two significant peaks in δ13C and δD of CH4 sources in 1998 and 2003 due to the wildfire emissions in boreal areas and in Europe. Title: A 30-Year Record of the Isotopic Composition of Atmospheric Methane Author: Teama, Doaa Galal Mohammed Year: 2013 Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year time horizon). Its atmospheric concentration has more than doubled from the preindustrial era due to anthropogenic activities such as rice cultivation, biomass burning, and fossil fuel production. However, the rate of increase of atmospheric CH4 (or the growth rate) slowed from 1980 until present. The main reason for this trend is a slowdown in the trend of CH4 sources. Measuring stable isotopes of atmospheric CH4 can constrain changes of CH4 sources. The main goal of this work is to interpret the CH4 trend from 1978-2010 in terms of its sources using measurements of CH4 mixing ratio and its isotopes. The current work presents the measurements and analysis of CH4 and its isotopes (δ13C and δD) of four air archive sample sets collected by the Oregon Graduate Institute (OGI). CH4 isotope ratios (δ13C and δD) were measured by a continuous flow isotope ratio mass spectrometer technique developed at PSU. The first set is for Cape Meares, Oregon which is the oldest and longest set and spans 1977-1999. The integrity of this sample set was evaluated by comparing between our measured CH4 mixing ratio values with those measured values by OGI and was found to be stable. Resulting CH4 seasonal cycle was evaluated from the Cape Meares data. The CH4 seasonal cycle shows a broad maximum during October-April and a minimum between July and August. The seasonal cycles of δ13C and δD have maximum values in May for δ13C and in July for δD and minimum values between September-October for δ13C and in October for δD. These results indicate a CH4 source that is more enriched January-May (e.g. biomass burning) and a source that is more depleted August-October (e.g. microbial). In addition to Cape Meares, air archive sets were analyzed from: South Pole (SPO), Samoa (SMO), Mauna Loa (MLO) 1992-1996. The presented δD measurements are unique measured values during these time periods at these stations. To obtain the long-term in isotopic CH4 from 1978-2010, other datasets of Northern Hemisphere mid-latitude sites are included with Cape Meares. These sites are Olympic Peninsula, Washington; Montaña de Oro, California; and Niwot Ridge, Colorado. The seasonal cycles of CH4 and its isotopes from the composite dataset have the same phase and amplitudes as the Cape Meares site. CH4 growth rate shows a decrease over time 1978-2010 with three main spikes in 1992, 1998, and 2003 consistent with the literature from the global trend. CH4 lifetime is estimated to 9.7 yrs. The δ13C trend in the composite data shows a slow increase from 1978-1987, a more rapid rate of change 1987-2005, and a gradual depletion during 2005-2010. The δD trend in the composite data shows a gradual increase during 1978-2001 and decrease from 2001-2005. From these results, the global CH4 emissions are estimated and show a leveling off sources 1982-2010 with two large peak anomalies in 1998 and 2003. The global average δ13C and δD of CH4 sources are estimated from measured values. The results of these calculations indicate that there is more than one source which controls the decrease in the global CH4 trend. From 1982-2001, δ13C and δD of CH4 sources becomes more depleted due to a decrease in fossil and/or biomass burning sources relative to microbial sources. From 2005-2010, δ13C of CH4 sources returns to its 1981 value. There are two significant peaks in δ13C and δD of CH4 sources in 1998 and 2003 due to the wildfire emissions in boreal areas and in Europe. Close

• 3. [Article] Decreasing Emissions of Methane from Rice Agriculture

  Methane emissions from rice fields are controlled by several key factors. The most important are the application of organic soil amendments and water management: whether the fields are flooded intermittently ...

  Citation × Citation Citation Abstract Copy Title: Decreasing Emissions of Methane from Rice Agriculture Author: Khalil, M. A. K., Shearer, Martha J. Year: 2006 Methane emissions from rice fields are controlled by several key factors. The most important are the application of organic soil amendments and water management: whether the fields are flooded intermittently or continuously. The total annual emissions from any country or the world are thus affected by the area of rice harvested, and a composite emission factor that takes into account how the various agricultural practices are distributed in terms of fertilizer use and water management, as well as other less important variables. Over decades the area of rice harvested changes but so does the composite emission factor. The product therefore, may change substantially over decadal time scales. We will argue that for China at least, there are downward trends of both area and emission factor leading to a substantial reduction of annual emissions over the last two decades from some 30 Tg/yr to perhaps less than 10 Tg/yr. The changes that cause these reductions would increase nitrous oxide emissions from rice fields as organic fertilizers are replaced with nitrogen based fertilizers. Similar changes are likely to be occurring world-wide. These trends of emissions are probably represented in the observed slowdown of methane trend in the atmosphere and the continuing steady increase of nitrous oxide. Title: Decreasing Emissions of Methane from Rice Agriculture Author: Khalil, M. A. K., Shearer, Martha J. Year: 2006 Methane emissions from rice fields are controlled by several key factors. The most important are the application of organic soil amendments and water management: whether the fields are flooded intermittently or continuously. The total annual emissions from any country or the world are thus affected by the area of rice harvested, and a composite emission factor that takes into account how the various agricultural practices are distributed in terms of fertilizer use and water management, as well as other less important variables. Over decades the area of rice harvested changes but so does the composite emission factor. The product therefore, may change substantially over decadal time scales. We will argue that for China at least, there are downward trends of both area and emission factor leading to a substantial reduction of annual emissions over the last two decades from some 30 Tg/yr to perhaps less than 10 Tg/yr. The changes that cause these reductions would increase nitrous oxide emissions from rice fields as organic fertilizers are replaced with nitrogen based fertilizers. Similar changes are likely to be occurring world-wide. These trends of emissions are probably represented in the observed slowdown of methane trend in the atmosphere and the continuing steady increase of nitrous oxide. Close

• 4. [Article] Variability in Winter Mass Balance of Northern Hemisphere Glaciers and Relations with Atmospheric Circulation

  An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. ...

  Citation × Citation Citation Abstract Copy Title: Variability in Winter Mass Balance of Northern Hemisphere Glaciers and Relations with Atmospheric Circulation Author: McCabe, Gregory J., Fountain, Andrew G., Dyurgerov, Mark Year: 2000 An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. The first mode of variability characterizes WMB variability in Northern and Central Europe and the second mode primarily represents WMB variability in northwestern North America, but also is related to variability in WMB of one glacier in Europe and one in Central Asia. These two modes of WMB variability are explained by variations in mesoscale atmospheric circulation which are driving forces of variations in surface temperature and precipitation. The first mode is highly correlated with the Arctic Oscillation Index, whereas the second mode is highly correlated with the Southern Oscillation Index. In addition, the second mode of WMB variability is highly correlated with variability in global winter temperatures. This result suggests some connection between global temperature trends and WMB for some glaciers. Title: Variability in Winter Mass Balance of Northern Hemisphere Glaciers and Relations with Atmospheric Circulation Author: McCabe, Gregory J., Fountain, Andrew G., Dyurgerov, Mark Year: 2000 An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. The first mode of variability characterizes WMB variability in Northern and Central Europe and the second mode primarily represents WMB variability in northwestern North America, but also is related to variability in WMB of one glacier in Europe and one in Central Asia. These two modes of WMB variability are explained by variations in mesoscale atmospheric circulation which are driving forces of variations in surface temperature and precipitation. The first mode is highly correlated with the Arctic Oscillation Index, whereas the second mode is highly correlated with the Southern Oscillation Index. In addition, the second mode of WMB variability is highly correlated with variability in global winter temperatures. This result suggests some connection between global temperature trends and WMB for some glaciers. Close

• 5. [Article] Spatial and Temporal Patterns in the Influence of Land Use on Water Quality in Five Portland Area Creeks Representing Differing Levels of Urbanization

  While the negative effects of urban development on freshwater systems are well documented, impacts of human disturbance on water quality vary depending on land cover, local climate, and temporal and spatial ...

  Citation × Citation Citation Abstract Copy Title: Spatial and Temporal Patterns in the Influence of Land Use on Water Quality in Five Portland Area Creeks Representing Differing Levels of Urbanization Author: Chang, Heejun, Steele, Madeline, Bonak, Zoe Year: 2011 While the negative effects of urban development on freshwater systems are well documented, impacts of human disturbance on water quality vary depending on land cover, local climate, and temporal and spatial scales of analysis. To better understand this variation, we analyzed water quality data for a total of 15 sites from six Portland, Oregon area creeks at multiple spatial and temporal scales. The creeks are characterized by differing levels of urban development, from relatively pristine to highly developed. More than ten years of monthly data gathered by the Portland Bureau of Environmental Services were used to analyze temporal trends, and five years of these data were used to analyze spatial patterns. Analytes of interest were specific conductivity, dissolved oxygen, nitrate, phosphorus, total suspended solids, and temperature. These variables were compared to contributing area land use metrics at three scales: full contributing sub-basin, 100-meter riparian corridor, and 50-meter riparian corridor. We calculated seven land use metrics: population density, street density, Green Streets density, percent low density development, percent high density development, percent forested area, and percent agriculture. We found Spearman?s Rank Correlation Coefficient between the water quality parameters for annual, wet, and dry seasons and the land use metrics at each spatial scale for each parameter. The same water quality data were also analyzed for correlations to same day as well as 3-, 5-, and 7-day antecedent precipitation to examine relationships between water quality and environmental moisture conditions. Additionally, we used a Seasonal Kendall test to search for temporal trends. For each site included in the temporal analysis, changes in population density and street density metrics from 2000 to 2010 were compared to changes in water quality. Results vary across space, but generally confirm that urban development has negatively impacted the creeks. Specific conductivity, total suspended solids and nitrate are particularly sensitive to the level of urban development, especially following rain events. This work will help to better understand and mitigate urbanization impacts on freshwater systems. Title: Spatial and Temporal Patterns in the Influence of Land Use on Water Quality in Five Portland Area Creeks Representing Differing Levels of Urbanization Author: Chang, Heejun, Steele, Madeline, Bonak, Zoe Year: 2011 While the negative effects of urban development on freshwater systems are well documented, impacts of human disturbance on water quality vary depending on land cover, local climate, and temporal and spatial scales of analysis. To better understand this variation, we analyzed water quality data for a total of 15 sites from six Portland, Oregon area creeks at multiple spatial and temporal scales. The creeks are characterized by differing levels of urban development, from relatively pristine to highly developed. More than ten years of monthly data gathered by the Portland Bureau of Environmental Services were used to analyze temporal trends, and five years of these data were used to analyze spatial patterns. Analytes of interest were specific conductivity, dissolved oxygen, nitrate, phosphorus, total suspended solids, and temperature. These variables were compared to contributing area land use metrics at three scales: full contributing sub-basin, 100-meter riparian corridor, and 50-meter riparian corridor. We calculated seven land use metrics: population density, street density, Green Streets density, percent low density development, percent high density development, percent forested area, and percent agriculture. We found Spearman?s Rank Correlation Coefficient between the water quality parameters for annual, wet, and dry seasons and the land use metrics at each spatial scale for each parameter. The same water quality data were also analyzed for correlations to same day as well as 3-, 5-, and 7-day antecedent precipitation to examine relationships between water quality and environmental moisture conditions. Additionally, we used a Seasonal Kendall test to search for temporal trends. For each site included in the temporal analysis, changes in population density and street density metrics from 2000 to 2010 were compared to changes in water quality. Results vary across space, but generally confirm that urban development has negatively impacted the creeks. Specific conductivity, total suspended solids and nitrate are particularly sensitive to the level of urban development, especially following rain events. This work will help to better understand and mitigate urbanization impacts on freshwater systems. Close

• 6. [Article] A Dynamic Physical Model for Soil Temperature and Water in Taylor Valley, Antarctica

  We developed a simulation model for terrestrial sites including sensible heat exchange between the atmosphere and ground surface, inter- and intra-layer heat conduction by rock and soil, and shortwave ...

  Citation × Citation Citation Abstract Copy Title: A Dynamic Physical Model for Soil Temperature and Water in Taylor Valley, Antarctica Author: Hunt, H. W., Fountain, Andrew G., Doran, Peter T., Basagic, Hassan J. Year: 2010 We developed a simulation model for terrestrial sites including sensible heat exchange between the atmosphere and ground surface, inter- and intra-layer heat conduction by rock and soil, and shortwave and longwave radiation. Water fluxes included snowmelt, freezing/thawing of soil water, soil capillary flow, and vapour flows among atmosphere, soil, and snow. The model accounted for 96-99% of variation in soil temperature data. No long-term temporal trends in soil temperature were apparent. Soil water vapour concentration in thawed surface soil in summer often was higher than in frozen deeper soils, leading to downward vapour fluxes. Katabatic winds caused a reversal of the usual winter pattern of upward vapour fluxes. The model exhibited a steady state depth distribution of soil water due to vapour flows and in the absence of capillary flows below the top 0.5 cm soil layer. Beginning with a completely saturated soil profile, soil water was lost rapidly, and within a few hundred years approached a steady state characterized by dry soil (,0.5% gravimetric) down to one metre depth and saturated soil below that. In contrast, it took 42,000 years to approach steady state beginning from a completely dry initial condition. Title: A Dynamic Physical Model for Soil Temperature and Water in Taylor Valley, Antarctica Author: Hunt, H. W., Fountain, Andrew G., Doran, Peter T., Basagic, Hassan J. Year: 2010 We developed a simulation model for terrestrial sites including sensible heat exchange between the atmosphere and ground surface, inter- and intra-layer heat conduction by rock and soil, and shortwave and longwave radiation. Water fluxes included snowmelt, freezing/thawing of soil water, soil capillary flow, and vapour flows among atmosphere, soil, and snow. The model accounted for 96-99% of variation in soil temperature data. No long-term temporal trends in soil temperature were apparent. Soil water vapour concentration in thawed surface soil in summer often was higher than in frozen deeper soils, leading to downward vapour fluxes. Katabatic winds caused a reversal of the usual winter pattern of upward vapour fluxes. The model exhibited a steady state depth distribution of soil water due to vapour flows and in the absence of capillary flows below the top 0.5 cm soil layer. Beginning with a completely saturated soil profile, soil water was lost rapidly, and within a few hundred years approached a steady state characterized by dry soil (,0.5% gravimetric) down to one metre depth and saturated soil below that. In contrast, it took 42,000 years to approach steady state beginning from a completely dry initial condition. Close

• 7. [Article] Predicted Effects of Gypsy Moth Defoliation and Climate Change on Forest Carbon Dynamics in the New Jersey Pine Barrens

  Disturbance regimes within temperate forests can significantly impact carbon cycling. Additionally, projected climate change in combination with multiple, interacting disturbance effects may disrupt the ...

  Citation × Citation Citation Abstract Copy Title: Predicted Effects of Gypsy Moth Defoliation and Climate Change on Forest Carbon Dynamics in the New Jersey Pine Barrens Author: Kretchun, Alec M., Scheller, Robert M., Lucash, Melissa S., Clark, Kenneth L., Hom, John, Van Tuyl, Steve Year: 2014 Disturbance regimes within temperate forests can significantly impact carbon cycling. Additionally, projected climate change in combination with multiple, interacting disturbance effects may disrupt the capacity of forests to act as carbon sinks at large spatial and temporal scales. We used a spatially explicit forest succession and disturbance model, LANDIS-II, to model the effects of climate change, gypsy moth (Lymantria dispar L.) defoliation, and wildfire on the C dynamics of the forests of the New Jersey Pine Barrens over the next century. Climate scenarios were simulated using current climate conditions (baseline), as well as a high emissions scenario (HadCM3 A2 emissions scenario). Our results suggest that long-term changes in C cycling will be driven more by climate change than by fire or gypsy moths over the next century. We also found that simulated disturbances will affect species composition more than tree growth or C sequestration rates at the landscape level. Projected changes in tree species biomass indicate a potential increase in oaks with climate change and gypsy moth defoliation over the course of the 100-year simulation, exacerbating current successional trends towards increased oak abundance. Our research suggests that defoliation under climate change may play a critical role in increasing the variability of tree growth rates and in determining landscape species composition over the next 100 years. Title: Predicted Effects of Gypsy Moth Defoliation and Climate Change on Forest Carbon Dynamics in the New Jersey Pine Barrens Author: Kretchun, Alec M., Scheller, Robert M., Lucash, Melissa S., Clark, Kenneth L., Hom, John, Van Tuyl, Steve Year: 2014 Disturbance regimes within temperate forests can significantly impact carbon cycling. Additionally, projected climate change in combination with multiple, interacting disturbance effects may disrupt the capacity of forests to act as carbon sinks at large spatial and temporal scales. We used a spatially explicit forest succession and disturbance model, LANDIS-II, to model the effects of climate change, gypsy moth (Lymantria dispar L.) defoliation, and wildfire on the C dynamics of the forests of the New Jersey Pine Barrens over the next century. Climate scenarios were simulated using current climate conditions (baseline), as well as a high emissions scenario (HadCM3 A2 emissions scenario). Our results suggest that long-term changes in C cycling will be driven more by climate change than by fire or gypsy moths over the next century. We also found that simulated disturbances will affect species composition more than tree growth or C sequestration rates at the landscape level. Projected changes in tree species biomass indicate a potential increase in oaks with climate change and gypsy moth defoliation over the course of the 100-year simulation, exacerbating current successional trends towards increased oak abundance. Our research suggests that defoliation under climate change may play a critical role in increasing the variability of tree growth rates and in determining landscape species composition over the next 100 years. Close

• 8. [Article] The Production of Organic Nitrates in Portland Oregon and the Columbia River Gorge

  This work studied the production of aerosol-phase organic nitrates in both Portland and the Columbia River Gorge (CRG). Ozone and NOx species were investigated for correlation with organic nitrate aerosol, ...

  Citation × Citation Citation Abstract Copy Title: The Production of Organic Nitrates in Portland Oregon and the Columbia River Gorge Author: Neill, Holly Ann Year: 2013 This work studied the production of aerosol-phase organic nitrates in both Portland and the Columbia River Gorge (CRG). Ozone and NOx species were investigated for correlation with organic nitrate aerosol, as they function as precursors to the production of organic nitrates. These ambient gas-phase measurements were collected in the same locations as high-volume (Hi-Vol) filters samples, in an urban and rural gorge setting to investigate correlations at the origin of the pollution plume and downwind. A novel Soxhlet extraction method for Hi-Vol filters was developed based on literature and EPA standard methods. Analysis for nitrate production was done by segregating data based on times when the wind blew out of Portland and down the CRG versus times when flow was not westerly. Filters were then compared to ambient gas-phase measurements and derived NO3 radical production rates to look for trends. Wind direction had a strong influence on the concentrations of precursor molecules in the CRG. On days with a westerly wind direction into the gorge, concentrations of the measure aerosol organic nitrates were similar at both sides. This suggests some contribution of a broader regional production of organic nitrates. There was some correlation between the production rate of NO3 radicals and the measured organic nitrate aerosol, suggesting a role for NO3 + VOC production of organic nitrates that later partition to the aerosol phase. This information will better illuminate the fate of nitrogen downwind of pollution sources. The information will also help to create a better understanding of the way topography and meteorological conditions can influence the flow of pollution. Understanding the downwind oxidative chemistry that happens in the CRG would better support both pollution prevention and mitigation efforts. Title: The Production of Organic Nitrates in Portland Oregon and the Columbia River Gorge Author: Neill, Holly Ann Year: 2013 This work studied the production of aerosol-phase organic nitrates in both Portland and the Columbia River Gorge (CRG). Ozone and NOx species were investigated for correlation with organic nitrate aerosol, as they function as precursors to the production of organic nitrates. These ambient gas-phase measurements were collected in the same locations as high-volume (Hi-Vol) filters samples, in an urban and rural gorge setting to investigate correlations at the origin of the pollution plume and downwind. A novel Soxhlet extraction method for Hi-Vol filters was developed based on literature and EPA standard methods. Analysis for nitrate production was done by segregating data based on times when the wind blew out of Portland and down the CRG versus times when flow was not westerly. Filters were then compared to ambient gas-phase measurements and derived NO3 radical production rates to look for trends. Wind direction had a strong influence on the concentrations of precursor molecules in the CRG. On days with a westerly wind direction into the gorge, concentrations of the measure aerosol organic nitrates were similar at both sides. This suggests some contribution of a broader regional production of organic nitrates. There was some correlation between the production rate of NO3 radicals and the measured organic nitrate aerosol, suggesting a role for NO3 + VOC production of organic nitrates that later partition to the aerosol phase. This information will better illuminate the fate of nitrogen downwind of pollution sources. The information will also help to create a better understanding of the way topography and meteorological conditions can influence the flow of pollution. Understanding the downwind oxidative chemistry that happens in the CRG would better support both pollution prevention and mitigation efforts. Close

• 9. [Article] Effects of Runoff Sensitivity and Catchment Characteristics on Regional Actual Evapotranspiration Trends in the Conterminous US

  An understanding of the role of hydro-climatic and geographic regimes on regional actual evapotranspiration (AET) change is essential to improving our knowledge on predicting water availability in a changing ...

  Citation × Citation Citation Abstract Copy Title: Effects of Runoff Sensitivity and Catchment Characteristics on Regional Actual Evapotranspiration Trends in the Conterminous US Author: Jung, Il-Won, Chang, Heejun, Risley, John Year: 2013 An understanding of the role of hydro-climatic and geographic regimes on regional actual evapotranspiration (AET) change is essential to improving our knowledge on predicting water availability in a changing climate. This study investigates the relationship between AET change for a 60 year period (1951–2010) and the runoff sensitivity in 255 undisturbed catchments over the US. The runoff sensitivity to climate change is simply defined as the relative magnitude between runoff and precipitation changes with time. Runoff sensitivity can readily explain the conflicting directions of AET changes under similar precipitation change. Under increasing precipitation, AET decreases when runoff is increasing more rapidly than precipitation based on the water balance. Conversely, AET increases when runoff is decreasing more rapidly than precipitation. This result indicates that runoff sensitivity to climate change is a key factor for understanding regional water availability change at the catchment scale. In addition, a stepwise multiple regression analysis and a geographically weighted regression analysis show that the portion of evergreen forest and the mean elevation of a catchment may play a secondary role in the spatial pattern of the AET change, and the relative importance of such explanatory variables may change over space. Title: Effects of Runoff Sensitivity and Catchment Characteristics on Regional Actual Evapotranspiration Trends in the Conterminous US Author: Jung, Il-Won, Chang, Heejun, Risley, John Year: 2013 An understanding of the role of hydro-climatic and geographic regimes on regional actual evapotranspiration (AET) change is essential to improving our knowledge on predicting water availability in a changing climate. This study investigates the relationship between AET change for a 60 year period (1951–2010) and the runoff sensitivity in 255 undisturbed catchments over the US. The runoff sensitivity to climate change is simply defined as the relative magnitude between runoff and precipitation changes with time. Runoff sensitivity can readily explain the conflicting directions of AET changes under similar precipitation change. Under increasing precipitation, AET decreases when runoff is increasing more rapidly than precipitation based on the water balance. Conversely, AET increases when runoff is decreasing more rapidly than precipitation. This result indicates that runoff sensitivity to climate change is a key factor for understanding regional water availability change at the catchment scale. In addition, a stepwise multiple regression analysis and a geographically weighted regression analysis show that the portion of evergreen forest and the mean elevation of a catchment may play a secondary role in the spatial pattern of the AET change, and the relative importance of such explanatory variables may change over space. Close

• 10. [Article] Engaging Recreational Fishers in Management and Conservation: Global Case Studies

  Globally, the number of recreational fishers is sizeable and increasing in many countries. Associated with this trend is the potential for negative impacts on fish stocks through exploitation or management ...

  Citation × Citation Citation Abstract Copy Title: Engaging Recreational Fishers in Management and Conservation: Global Case Studies Author: Granek, Elise F., Madin, Elizabeth M.P., Brown, M. A., Figueira, Will F., Cameron, Darren S., Hogan, Zeb, Kristianson, Gerry, de Villiers, Pierre, Williams, Jack E., Post, John R., Zahn, S., Arlinghaus, R. Year: 2008 Globally, the number of recreational fishers is sizeable and increasing in many countries. Associated with this trend is the potential for negative impacts on fish stocks through exploitation or management measures such as stocking and introduction of non-native fishes. Nevertheless, recreational fishers can be instrumental in successful fisheries conservation through active involvement in, or initiation of, conservation projects to reduce both direct and external stressors contributing to fishery declines. Understanding fishers’ concerns for sustained access to the resource and developing methods for their meaningful participation can have positive impacts on conservation efforts. We examined a suite of case studies that demonstrate successful involvement of recreational fishers in conservation and management activities that span developed and developing countries, temperate and tropical regions, marine and freshwater systems, and open- and closedaccess fisheries. To illustrate potential benefits and challenges of involving recreational fishers in fisheries management and conservation, we examined the socioeconomic and ecological contexts of each case study. We devised a conceptual framework for the engagement of recreational fishers that targets particular types of involvement (enforcement, advocacy, conservation, management design [type and location], research, and monitoring) on the basis of degree of stakeholder stewardship, scale of the fishery, and source of impacts (internal or external). These activities can be enhanced by incorporating local knowledge and traditions, taking advantage of leadership and regional networks, and creating collaborations among various stakeholder groups, scientists, and agencies to maximize the probability of recreational fisher involvement and project success. Title: Engaging Recreational Fishers in Management and Conservation: Global Case Studies Author: Granek, Elise F., Madin, Elizabeth M.P., Brown, M. A., Figueira, Will F., Cameron, Darren S., Hogan, Zeb, Kristianson, Gerry, de Villiers, Pierre, Williams, Jack E., Post, John R., Zahn, S., Arlinghaus, R. Year: 2008 Globally, the number of recreational fishers is sizeable and increasing in many countries. Associated with this trend is the potential for negative impacts on fish stocks through exploitation or management measures such as stocking and introduction of non-native fishes. Nevertheless, recreational fishers can be instrumental in successful fisheries conservation through active involvement in, or initiation of, conservation projects to reduce both direct and external stressors contributing to fishery declines. Understanding fishers’ concerns for sustained access to the resource and developing methods for their meaningful participation can have positive impacts on conservation efforts. We examined a suite of case studies that demonstrate successful involvement of recreational fishers in conservation and management activities that span developed and developing countries, temperate and tropical regions, marine and freshwater systems, and open- and closedaccess fisheries. To illustrate potential benefits and challenges of involving recreational fishers in fisheries management and conservation, we examined the socioeconomic and ecological contexts of each case study. We devised a conceptual framework for the engagement of recreational fishers that targets particular types of involvement (enforcement, advocacy, conservation, management design [type and location], research, and monitoring) on the basis of degree of stakeholder stewardship, scale of the fishery, and source of impacts (internal or external). These activities can be enhanced by incorporating local knowledge and traditions, taking advantage of leadership and regional networks, and creating collaborations among various stakeholder groups, scientists, and agencies to maximize the probability of recreational fisher involvement and project success. Close