Ivan Fernandez - Academia.edu (original) (raw)

Papers by Ivan Fernandez

Global change biology, Jan 29, 2016

A cross-site analysis was conducted on seven diverse, forested watersheds in the northeastern U.S... more A cross-site analysis was conducted on seven diverse, forested watersheds in the northeastern U.S. to evaluate hydrological responses (evapotranspiration, soil moisture, seasonal and annual streamflow, and water stress) to projections of future climate. We used output from four Atmosphere-Ocean General Circulation Models (AOGCMs) (CCSM4, HadGEM2-CC, MIROC5, and MRI-CGCM3) included in Phase 5 of the Coupled Model Intercomparison Project, coupled with two Representative Concentration Pathways (RCP 8.5 and 4.5). The coarse resolution AOGCMs outputs were statistically downscaled using an asynchronous regional regression model to provide finer resolution future climate projections as inputs to the deterministic dynamic ecosystem model PnET-BGC. Simulation results indicated that projected warmer temperatures and longer growing seasons in the northeastern U.S. are anticipated to increase evapotranspiration across all sites, although invoking CO2 effects on vegetation (growth enhancement an...

The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comment... more The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comments on this manuscript. Particular gratitude is extended to Stephen A. Norton for his efforts to help establish the Greenville NADP site at the beginning of the national network program. The authors are indebted to the Maine Agricultural and Forest Experiment Station for support of site operations and to the Moosehead Sanitary District for providing logistical support and personnel to the project. The senior author of this manuscript also wishes to express particular appreciation to his coauthor, who has worked tirelessly to assure the continuous operation of the Greenville NADP/NTN site since its establishment to the present.

Networks of perennial and intermittent streams and rivers cross Maine's private and public forest... more Networks of perennial and intermittent streams and rivers cross Maine's private and public forest land. Among the functions provided by these riparian forests, water quality has received considerable attention. Impacts of harvesting practices are an important concern and stringent water quality standards have been established. Preserving riparian forests is an essential part of compliance with those standards. However, changes in riparian function associated with various harvest intensities are poorly understood.

Water Air and Soil Pollution, Jan 31, 2002

Near-stream and upslope soil chemical properties were analyzed to infer linkages between soil and... more Near-stream and upslope soil chemical properties were analyzed to infer linkages between soil and surface water chemistry at the Bear Brook Watershed in Maine [BBWM]. Organic and mineral soil samples were collected along six 20 m transects perpendicular to the stream and one 200 m transect parallel to the stream. O horizon soils immediately adjacent to the stream had a significantly higher pH (4.20) and lower soil organic matter percentage (54%) than upslope O horizons (3.84 and 76%, respectively). Additionally, near-stream O horizon soils had significantly higher concentrations of water-soluble Al (2.7 ×), exchangeable Al (2.3 ×), and organically-bound Al (3.9 ×) and significantly lower concentrations of exchangeable Ca (0.4 ×) than O horizons upslope. These results suggest that Al can accumulate in non-hydric near-stream zone soils at this site. Mobilization of labile Al from near-stream zone soils during hydrologic events could play a key role in explaining controls on Al in stream water at BBWM.

The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comment... more The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comments on this manuscript. Particular gratitude is extended to Stephen A. Norton for his efforts to help establish the Greenville NADP site at the beginning of the national network program. The authors are indebted to the Maine Agricultural and Forest Experiment Station for support of site operations and to the Moosehead Sanitary District for providing logistical support and personnel to the project. The senior author of this manuscript also wishes to express particular appreciation to his coauthor, who has worked tirelessly to assure the continuous operation of the Greenville NADP/NTN site since its establishment to the present.

The Bear Brook Watershed in Maine (BBWM) is a long-term, whole-ecosystem chemical manipulation ex... more The Bear Brook Watershed in Maine (BBWM) is a long-term, whole-ecosystem chemical manipulation experiment. Treatments consist of bimonthly aerial applications of (NH4)2SO4 resulting in a 3X and 2X loading above ambient for N and S, respectively. The site consists of two adjacent ~10ha forested stream watersheds with distinct spruce and hardwood forest types. Stream chemistry responded rapidly to the treatments, including an approximately 6x increase in NO3 concentrations. Despite this increase, approximately 82 percent of the added N was retained within the system. In order to help elucidate mechanisms of N retention, soils were sampled quantitatively in 1998 following 9 years of treatment. Only small differences existed between watersheds in total soil N that largely reflected soil mass differences. This was not unexpected given that the total treatment N represented only ~2 percent of the total soil N. The total added N was ~ 20x greater than the combined pools of the more ephemeral exchangeable NH4-N + NO3-N, which were both greater in the treated watershed compared to the control. Potential net N mineralization and nitrification were also significantly greater in the treated watershed compared to the control. These differences were more evident in the softwood than the hardwood stands, due in part to anomalously high potential net N mineralization rates in one of the control hardwood soil types. These results underscore the importance of recognizing the varying contributions of different vegetation and soil types to whole watershed response to elevated N deposition.

Hydrology and Earth System Sciences, 2001

As atmospheric emissions of S have declined in the Northern Hemisphere, there has been an expecta... more As atmospheric emissions of S have declined in the Northern Hemisphere, there has been an expectation of increased pH and alkalinity in streams believed to have been acidified by excess S and N. Many streams and lakes have not recovered. Evidence from East Bear Brook in Maine, USA and modelling with the groundwater acid-base model MAGIC (Cosby et al. 1985a,b) indicate that seasonal and yearly variations in soil PCO2 are adequate to enhance or even reverse acid-base (alkalinity) changes anticipated from modest decreases of SO4 in surface waters. Alkalinity is generated in the soil by exchange of H+ from dissociation of H2CO3, which in turn is derived from the dissolving of soil CO2. The variation in soil PCO2 produces an alkalinity variation of up to 15 meq L-1 in stream water. Detecting and relating increases in alkalinity to decreases in stream SO4 are significantly more difficult in the short term because of this effect. For example, modelled alkalinity recovery at Bear Brook due to a decline of 20 meq SO4 L-1 in soil solution is compensated by a decline from 0.4 to 0.2% for soil air PCO2. This compensation ability decays over time as base saturation declines. Variable PCO2 has less effect in more acidic soils. Short-term decreases of PCO2 below the long-term average value produce short-term decreases in alkalinity, whereas short-term increases in PCO2 produce short-term alkalization. Trend analysis for detecting recovery of streams and lakes from acidification after reduced atmospheric emissions will require a longer monitoring period for statistical significance than previously appreciated.

Environmental Monitoring and Assessment, Mar 1, 1999

Environmental Monitoring and Assessment, Apr 1, 2007

Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in... more Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition would be higher at Hadlock Brook (the reference watershed, 10.2 μg/m 2 / year) than Cadillac (9.4 μg/m 2 /year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 μg/m 2 /year) than from Hadlock Brook watershed (1.3 μg/m 2 /year). DIN export from Cadillac Brook (11.5 eq/ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that ∼50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower soil pools, and greater ecosystem retention for both Hg and DIN.

Soil Science Society of America Journal, 1993

AGRIS record. Record number, US9430816. Titles, Soil carbon dioxide characteristics under differe... more AGRIS record. Record number, US9430816. Titles, Soil carbon dioxide characteristics under different forest types and after harvest. Personal Authors, Fernandez, IJ,Son, Y.,Kraske, CR,Rustad, LE,David, MB. Publication Date, (Jul-Aug 1993). AGRIS Subj. Cat. ...

Technical Bulletin Maine Agricultural Experiment Station, 1990

Environmental Geology, 2005

On 25 April 1998 the tailings dam of the Aznalcóllar mine burst, a great quantity of pyrite waste... more On 25 April 1998 the tailings dam of the Aznalcóllar mine burst, a great quantity of pyrite waste sludge and acid water was spilled reaching the vicinity of the Doñana National Park. In surface and ground water samples taken a week after dam breaking, metals, trace elements and Pb isotopic ratios ( 206 Pb/ 207 Pb and 208 Pb/ 206 Pb) were analysed. In September 1998 a second sampling survey was carried out. The surface waters have a similar isotopic composition as the lead contained in the pyrite from the Aznalcóllar mine. The polluted groundwater of the Guadiamar aquifer also shows the influence of the mining origin of the lead. Lead isotope ratios ( 206 Pb/ 207 Pb and 208 Pb/ 206 Pb) in the groundwater of the Almonte-Marismas are very low and they differ clearly from the rest of groundwater samples. A further group of wells has a lead isotope composition intermediate between the Aznalcóllar mine and the atmospheric aerosols of the Iberian Peninsula.

Treatise on Geochemistry, 2014

Global change biology, Jan 29, 2016

A cross-site analysis was conducted on seven diverse, forested watersheds in the northeastern U.S... more A cross-site analysis was conducted on seven diverse, forested watersheds in the northeastern U.S. to evaluate hydrological responses (evapotranspiration, soil moisture, seasonal and annual streamflow, and water stress) to projections of future climate. We used output from four Atmosphere-Ocean General Circulation Models (AOGCMs) (CCSM4, HadGEM2-CC, MIROC5, and MRI-CGCM3) included in Phase 5 of the Coupled Model Intercomparison Project, coupled with two Representative Concentration Pathways (RCP 8.5 and 4.5). The coarse resolution AOGCMs outputs were statistically downscaled using an asynchronous regional regression model to provide finer resolution future climate projections as inputs to the deterministic dynamic ecosystem model PnET-BGC. Simulation results indicated that projected warmer temperatures and longer growing seasons in the northeastern U.S. are anticipated to increase evapotranspiration across all sites, although invoking CO2 effects on vegetation (growth enhancement an...

The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comment... more The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comments on this manuscript. Particular gratitude is extended to Stephen A. Norton for his efforts to help establish the Greenville NADP site at the beginning of the national network program. The authors are indebted to the Maine Agricultural and Forest Experiment Station for support of site operations and to the Moosehead Sanitary District for providing logistical support and personnel to the project. The senior author of this manuscript also wishes to express particular appreciation to his coauthor, who has worked tirelessly to assure the continuous operation of the Greenville NADP/NTN site since its establishment to the present.

Networks of perennial and intermittent streams and rivers cross Maine's private and public forest... more Networks of perennial and intermittent streams and rivers cross Maine's private and public forest land. Among the functions provided by these riparian forests, water quality has received considerable attention. Impacts of harvesting practices are an important concern and stringent water quality standards have been established. Preserving riparian forests is an essential part of compliance with those standards. However, changes in riparian function associated with various harvest intensities are poorly understood.

Water Air and Soil Pollution, Jan 31, 2002

Near-stream and upslope soil chemical properties were analyzed to infer linkages between soil and... more Near-stream and upslope soil chemical properties were analyzed to infer linkages between soil and surface water chemistry at the Bear Brook Watershed in Maine [BBWM]. Organic and mineral soil samples were collected along six 20 m transects perpendicular to the stream and one 200 m transect parallel to the stream. O horizon soils immediately adjacent to the stream had a significantly higher pH (4.20) and lower soil organic matter percentage (54%) than upslope O horizons (3.84 and 76%, respectively). Additionally, near-stream O horizon soils had significantly higher concentrations of water-soluble Al (2.7 ×), exchangeable Al (2.3 ×), and organically-bound Al (3.9 ×) and significantly lower concentrations of exchangeable Ca (0.4 ×) than O horizons upslope. These results suggest that Al can accumulate in non-hydric near-stream zone soils at this site. Mobilization of labile Al from near-stream zone soils during hydrologic events could play a key role in explaining controls on Al in stream water at BBWM.

The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comment... more The authors wish to acknowledge John C. Brissette and Stephen A. Norton for their helpful comments on this manuscript. Particular gratitude is extended to Stephen A. Norton for his efforts to help establish the Greenville NADP site at the beginning of the national network program. The authors are indebted to the Maine Agricultural and Forest Experiment Station for support of site operations and to the Moosehead Sanitary District for providing logistical support and personnel to the project. The senior author of this manuscript also wishes to express particular appreciation to his coauthor, who has worked tirelessly to assure the continuous operation of the Greenville NADP/NTN site since its establishment to the present.

The Bear Brook Watershed in Maine (BBWM) is a long-term, whole-ecosystem chemical manipulation ex... more The Bear Brook Watershed in Maine (BBWM) is a long-term, whole-ecosystem chemical manipulation experiment. Treatments consist of bimonthly aerial applications of (NH4)2SO4 resulting in a 3X and 2X loading above ambient for N and S, respectively. The site consists of two adjacent ~10ha forested stream watersheds with distinct spruce and hardwood forest types. Stream chemistry responded rapidly to the treatments, including an approximately 6x increase in NO3 concentrations. Despite this increase, approximately 82 percent of the added N was retained within the system. In order to help elucidate mechanisms of N retention, soils were sampled quantitatively in 1998 following 9 years of treatment. Only small differences existed between watersheds in total soil N that largely reflected soil mass differences. This was not unexpected given that the total treatment N represented only ~2 percent of the total soil N. The total added N was ~ 20x greater than the combined pools of the more ephemeral exchangeable NH4-N + NO3-N, which were both greater in the treated watershed compared to the control. Potential net N mineralization and nitrification were also significantly greater in the treated watershed compared to the control. These differences were more evident in the softwood than the hardwood stands, due in part to anomalously high potential net N mineralization rates in one of the control hardwood soil types. These results underscore the importance of recognizing the varying contributions of different vegetation and soil types to whole watershed response to elevated N deposition.

Hydrology and Earth System Sciences, 2001

As atmospheric emissions of S have declined in the Northern Hemisphere, there has been an expecta... more As atmospheric emissions of S have declined in the Northern Hemisphere, there has been an expectation of increased pH and alkalinity in streams believed to have been acidified by excess S and N. Many streams and lakes have not recovered. Evidence from East Bear Brook in Maine, USA and modelling with the groundwater acid-base model MAGIC (Cosby et al. 1985a,b) indicate that seasonal and yearly variations in soil PCO2 are adequate to enhance or even reverse acid-base (alkalinity) changes anticipated from modest decreases of SO4 in surface waters. Alkalinity is generated in the soil by exchange of H+ from dissociation of H2CO3, which in turn is derived from the dissolving of soil CO2. The variation in soil PCO2 produces an alkalinity variation of up to 15 meq L-1 in stream water. Detecting and relating increases in alkalinity to decreases in stream SO4 are significantly more difficult in the short term because of this effect. For example, modelled alkalinity recovery at Bear Brook due to a decline of 20 meq SO4 L-1 in soil solution is compensated by a decline from 0.4 to 0.2% for soil air PCO2. This compensation ability decays over time as base saturation declines. Variable PCO2 has less effect in more acidic soils. Short-term decreases of PCO2 below the long-term average value produce short-term decreases in alkalinity, whereas short-term increases in PCO2 produce short-term alkalization. Trend analysis for detecting recovery of streams and lakes from acidification after reduced atmospheric emissions will require a longer monitoring period for statistical significance than previously appreciated.

Environmental Monitoring and Assessment, Mar 1, 1999

Environmental Monitoring and Assessment, Apr 1, 2007

Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in... more Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition would be higher at Hadlock Brook (the reference watershed, 10.2 μg/m 2 / year) than Cadillac (9.4 μg/m 2 /year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 μg/m 2 /year) than from Hadlock Brook watershed (1.3 μg/m 2 /year). DIN export from Cadillac Brook (11.5 eq/ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that ∼50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower soil pools, and greater ecosystem retention for both Hg and DIN.

Soil Science Society of America Journal, 1993

AGRIS record. Record number, US9430816. Titles, Soil carbon dioxide characteristics under differe... more AGRIS record. Record number, US9430816. Titles, Soil carbon dioxide characteristics under different forest types and after harvest. Personal Authors, Fernandez, IJ,Son, Y.,Kraske, CR,Rustad, LE,David, MB. Publication Date, (Jul-Aug 1993). AGRIS Subj. Cat. ...

Technical Bulletin Maine Agricultural Experiment Station, 1990

Environmental Geology, 2005

On 25 April 1998 the tailings dam of the Aznalcóllar mine burst, a great quantity of pyrite waste... more On 25 April 1998 the tailings dam of the Aznalcóllar mine burst, a great quantity of pyrite waste sludge and acid water was spilled reaching the vicinity of the Doñana National Park. In surface and ground water samples taken a week after dam breaking, metals, trace elements and Pb isotopic ratios ( 206 Pb/ 207 Pb and 208 Pb/ 206 Pb) were analysed. In September 1998 a second sampling survey was carried out. The surface waters have a similar isotopic composition as the lead contained in the pyrite from the Aznalcóllar mine. The polluted groundwater of the Guadiamar aquifer also shows the influence of the mining origin of the lead. Lead isotope ratios ( 206 Pb/ 207 Pb and 208 Pb/ 206 Pb) in the groundwater of the Almonte-Marismas are very low and they differ clearly from the rest of groundwater samples. A further group of wells has a lead isotope composition intermediate between the Aznalcóllar mine and the atmospheric aerosols of the Iberian Peninsula.

Treatise on Geochemistry, 2014