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Sample records for acidified forested catchment

  1. Salt in the wound: The interfering effect of road salt on acidified forest catchments.

    PubMed

    Schweiger, Andreas H; Audorff, Volker; Beierkuhnlein, Carl

    2015-11-01

    Atmospheric acidic depositions have strongly altered the functioning and biodiversity of Central European forest ecosystems. Most impacts occurred until the end of the 20(th) century but the situation substantially improved thereafter caused by legal regulations in the late 1980's to reduce acidifying atmospheric pollution. Since then slow recovery from acidification has been observed in forested catchments and adjacent waters. However, trends of recovery are inconsistent and underlying mechanisms diminishing recovery are still poorly understood. We propose that the input of road salt can significantly affect acidity regime and acidification recovery of forest ecosystems. By comparing the discharge hydro-chemistry and plant community composition of springs fed by forested catchments with and without high levels of salt input over two decades we observed a significant suppression of recovery and elevated levels of nutrient leaching (K(+), Ca(2+) and Mg(2+)) in highly salt contaminated catchments. We show that the pollution of near-surface groundwater (interflow) by road salt application can have lasting effects on ecosystem processes over distances of several hundred metres apart from the salt emitting road. PMID:26115338

  2. SOLUBLE ALUMINUM IN ACIDIFIED ORGANIC HORIZONS OF FOREST SOILS

    EPA Science Inventory

    Concentrations of labile and total Al in soil extracts were measured as a function of equilibrium solution pH in six forest soil organic horizons acidified with HNO, (0-20 cmol H+.kg-1) under controlled conditions of ionic strength (0.05 M NaNO3), temperature (23 C), and solution...

  3. [Effect of flue gas desulfurization gypsum application on remediation of acidified forest soil].

    PubMed

    Luo, Yao; Kang, Rong-Hua; Yu, De-Xiang; Tan, Bing-Quan; Duan, Lei

    2012-06-01

    Effect of flue gas desulfurization gypsum (FGDG) application on remediation of a typical acidified forest soil was studied through field experiments at Tieshanping, Chongqing in southwest China for one year. To evaluate the effect and risk of FGDG application, pH value, major ions and heavy metal of soil water in different soil layers were observed dynamically, and heavy metal contained in soil and FGDG were measured. Results showed that Ca2+ and SO4(-2) concentration of soil water in FGDG plots increased with time, pH value was elevated slightly, and n(Ca)/n(Al) value of annual average increased from 2.16, 1.35 and 0.88 to 2.58, 1.52 and 1.12 compared with control plots. The concentration of As, Cu, Cr, Ni and Zn in soil water was not elevated significantly. However, slight enrichment of Cr, Ni and Zn in some upper soil layers was observed. Consequently, FGDG application can improve acidified forest soil, without obviously heavy metal increasing in soil water. However, risk for heavy metal enrichment still exists, which is need for further study. PMID:22946189

  4. [Effect of limestone and magnesite application on remediation of acidified forest soil in Chongqing, China].

    PubMed

    Yang, Yong-sen; Duan, Lei; Jin, Teng; Zhao, Da-wei; Zhang, Dong-bao; Hao, Ji-ming

    2006-09-01

    Effect of limestone and magnesite application on remediation of a typical acidified soil under a masson pine (Pinus massoniana) forest at Tieshanping, Chongqing in southwest China was studied through field experiments. The changes of soil water chemistry in different layers within one year after application of limestone or magnesite indicated that the remediation agents leaded to the recovery of acidified soil by significant increase of pH value and concentration of relative cation, i.e., Ca2+ or Mg2+, and notable decrease of inorganic monomeric aluminum (Ali). However, the accelerated leaching of NO3- and SO4(2-) might somewhat counteract the positive effects. Since the limestone powder applied was much finer and thus more soluble than the magnesite powder, it seemed that the addition of limestone was more effective than that of magnesite. However, the application of magnesite could probably improve the nutrient uptake and growth of plant, and thus limestone and magnesite should be used together. The change of soil water chemistry was much more notable in upper layer of soil than lower, which means that it will take long time to achieve the whole profile soil remediation. PMID:17117649

  5. Effects of calcite and magnesite application to a declining Masson pine forest on strongly acidified soil in Southwestern China.

    PubMed

    Huang, Yongmei; Kang, Ronghua; Ma, Xiaoxiao; Qi, Yu; Mulder, Jan; Duan, Lei

    2014-05-15

    Liming of strongly acidified soil under a Masson pine (Pinus massoniana Lamb.) forest was studied through a seven-year field manipulation experiment at Tieshanping, Chongqing in Southwestern China. To distinguish between the individual effects of Ca(2+) and Mg(2+) addition, we separately applied calcite (CaCO3) and magnesite (MgCO3), rather than using dolomite [CaMg(CO3)2]. Both calcite and magnesite additions caused a significant increase in pH and a decrease in dissolved inorganic monomeric aluminium (Ali) concentration of soil water. Ecological recovery included increases of herb biomass (both treatments) and Mg content in Masson pine needles (magnesite treatment only). However, the growth rate of Masson pine did not increase under either treatment, possibly because of nutrient imbalance due to phosphorus (P) deficiency or limited observation period. In China, acid deposition in forest ecosystems commonly coincides with large inputs of atmogenic Ca(2+), both enhancing Mg(2+) leaching. Calcite addition may further decrease the Mg(2+) availability in soil water, thereby exacerbating Mg(2+) deficiency in the acidified forest soils of southern and southwestern China. The effect of anthropogenic acidification of naturally acid forest soils on P availability needs further study. PMID:24631610

  6. Runoff Responses to Forest Thinning at Plot and Catchment Scales in a Headwater Catchment Draining Japanese Cypress Forest

    EPA Science Inventory

    We examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catc...

  7. Leaching of nitrogen from forested catchments in Finland

    NASA Astrophysics Data System (ADS)

    Kortelainen, Pirkko; Saukkonen, Sari; Mattsson, Tuija

    1997-12-01

    This study provides an assessment on the spatial variability of the long-term leaching (8-23 years) of nitrogen and organic carbon from 22 forested catchments (0.69-56 km2). The catchments are located throughout Finland excluding the northernmost regions. The Kruunuoja catchment is located in a national park; the other catchments represent typical Finnish forestry land. The leaching from the 21 forestry land catchments can be considered to represent average leaching from Finnish forestry land since the most important forestry practices (ditching, clear-cutting, scarification, and fertilization) since the 1960s have affected about 2.4% of the catchment area per year (compare 2.5% in the entire country in 1980 and 2% in 1991). Moreover, the mean annual runoff from the catchments, 230-420 mm yr-1, agree with the mean annual runoff from Finland (301 mm yr-1 from 1931 to 1990). The major part of the nitrogen transported from the catchments consisted of organic nitrogen (on average 79%). The average inorganic nitrogen proportion ((NO3-N + NH4-N)/Ntot) was lowest (7.3%) in the Kruunuoja catchment and was highest (54%) in the southernmost Teeressuonoja catchment located in the highest anthropogenic nitrogen deposition area. The median C/N ratio in the study streams was high, ranging from 34 to 66. Nitrate leaching from the catchments varied between 2.8 (Kruunuoja) and 100 kg km-2 yr-1 (Teeressuonoja) and was negatively related to C/N ratio in stream water and latitude. The stepwise multiple regression model selected C/N ratio and nitrogen deposition which together explained 72% of the variation in NO3-N leaching. Retention of NO3-N deposition (calculated as ((input-output)/input) was high in all catchments, ranging from 0.99 in Kruunuoja to 0.67 in Teeressuonoja.

  8. Sediment dynamics in an overland flow-prone forest catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, Alexander; Elsenbeer, Helmut

    2010-05-01

    Vegetation controls erosion in many respects, and it is assumed that forest cover is an effective control. Currently, most literature on erosion processes in forest ecosystems support this impression and estimates of sediment export from forested catchments serve as benchmarks to evaluate erosion processes under different land uses. Where soil properties favor near-surface flow paths, however, vegetation may not mitigate surface erosion. In the forested portion of the Panama Canal watershed overland flow is widespread and occurs frequently, and indications of active sediment transport are hard to overlook. In this area we selected a 9.7 ha catchment for a high-resolution study of suspended sediment dynamics. We equipped five nested catchments to elucidate sources, drivers, magnitude and timing of suspended sediment export by continuous monitoring of overland flow and stream flow and by simultaneous, event-based sediment sampling. The support program included monitoring throughfall, splash erosion, overland-flow connectivity and a survey of infiltrability, permeability, and aggregate stability. This dataset allowed a comprehensive view on erosion processes. We found that overland flow controls the suspended-sediment dynamics in channels. Particularly, rainfalls of high intensity at the end of the rainy season have a superior impact on the overall sediment export. During these events, overland flow occurs catchment-wide up to the divide and so does erosion. With our contribution we seek to provide evidence that forest cover and large sediment yields are no contradiction in terms even in the absence of mass movements.

  9. BIOLOGICAL SINKS FOR N ADDITIONS TO A FORESTED CATCHMENT

    EPA Science Inventory

    The goal of our research is to identify and quantify sinks for experimental Nitrogen (N) additions to a forested catchment at the Bear Brooks Watershed in Maine (BBWM) where background N deposition rates are low (< 4 kg ha-1 yr1). itrogen is added bimonthly to an experimental cat...

  10. Examining the effects of forest thinning on runoff responses at different catchments scales in forested headwaters

    NASA Astrophysics Data System (ADS)

    Dung, B. X.; Gomi, T.; Onda, Y.; Kato, H.; Hiraoka, M.

    2012-12-01

    We conducted field observation in nested headwater catchments draining Japanese cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) forests at Tochigi prefectures for examining the effects of forest thinning on runoff generation at different catchment scales. 50% of the stems was removed with line thinning in catchment K2 (treatment catchment), while catchment K3 remained untreated as a control. We also monitored nested catchments within K2-1 (17.1 ha) as K2-2 (10.2 ha), K2-3 (3.7 ha) and K2-4 (5.1 ha), and within K3-1 (8.9 ha) as K3-2 (3.0 ha). Runoff from the catchments was monitored during the pre-thinning (from April, 2010 to May 2011), and the post-thinning periods (from June 2011 to July 2012). Paired-catchment and hydrograph separation analysis were used to evaluate the effects of forest thinning on runoff generation at different catchment scales. We developed the pre-thinning calibration equation for predicting post-thinning responses. Paired-catchment analysis revealed that annual catchment runoff increased 648 mm in K2-1, 414 mm in K2-2, 517 mm in K2-3 and 487 mm in K2-4 after the thinning. Both quick and delayed runoff components only increased significantly in the larger catchments of K2-1 and K2-2, while only delayed runoff components of smaller catchments (K2-3 and K2-4) increased significantly during the post-thinning period. Increases of quick runoff in large catchments could be associated with quick runoff response to soil surface compaction by line thinning and skid trail installation. Increases of delayed runoff in small catchment may be associated with increase in net precipitation and decrease in evapotranspiration. Our finding showed that changes in internal hydrological flow pathways and associated changes in runoff components due to forest harvesting differ depending on the catchment sizes.

  11. Examining the effects of forest thinning on hydrological processes at different catchment scales in forested headwater

    NASA Astrophysics Data System (ADS)

    Dung, Bui Xuan; Gomi, Takashi; Onda, Yuichi; Kato, Hiroaki; Hiraoka, Marino

    2013-04-01

    We conducted field observation in nested headwater catchments draining Japanese cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) forests at Tochigi prefecture for examining the effects of forest thinning on hydrological processes at different catchment scales. 50% of the stems was removed with line thinning in catchment K2 (treatment catchment), while catchment K3 remained untreated as a control. We monitored nested catchment within K2-1 (17.1 ha) as K2-2 (10.2 ha), K2-3 (3.7 ha) and K2-4 (5.1 ha), and within K3-1 (8.9 ha) as K3-2 (3.0 ha). Runoff from the catchments was monitored during the pre-thinning (from April, 2010 to May 2011), and the post-thinning periods (from June 2011 to December 2012). Paired-catchment and hydrograph separation analysis were used to evaluate the effects of forest thinning on hydrological processes at different catchment scales. We developed the pre-thinning calibration equation for predicting post-thinning behaviors. Paired catchment analysis revealed that annual catchment runoff increased 648 mm in K2-1, 414 mm in K2-2, 528 mm in K2-3, and 566 mm in K2-4 during the post-thinning period. Greater increase of flow in largest catchment (K2-1) was be due to the contribution of increased delayed flow from infiltrated water, reappearing as surface flow (i.e., quick flow) in the lower parts of the catchment, caused by harvested activities (logging, road, skid trail). Because both quick and delayed flows increased significantly in the larger catchments of K2-1 and K2-2, while only delayed flow of smaller catchments (K2-3 and K2-4) increased significantly during the post-thinning period. Delayed flow also increased greater in K2-3 and K2-4, smaller in K2-2 but greatest in K2-1. Moreover, the increasing contributions to runoff from deeper groundwater sources that are recharged in upslope subcatchments caused increase amount of flow. This was explained when increase of annual base flow (i.e., bedrock flow) of zero-order catchments

  12. Factors controlling mercury transport in an upland forested catchment

    USGS Publications Warehouse

    Scherbatskoy, T.; Shanley, J.B.; Keeler, G.J.

    1998-01-01

    Total mercury (Hg) deposition and input/output relationships were investigated in an 11-ha deciduous forested catchment in northern Vermont as part of ongoing evaluations of rig cycling and transport in the Lake Champlain basin. Atmospheric Hg deposition (precipitation + modeled vapor phase downward flux) was 425 mg ha-1 during the one-year period March 1994 through February 1995 and 463 mg ha-1 from March 1995 through February 1996. In the same periods, stream export of total Hg was 32 mg ha-1 and 22 mg ha-1, respectively. Thus, there was a net retention of Hg by the catchment of 92% the first year and 95% the second year. In the first year, 16.9 mg ha-1 or about half of the annual stream export, occurred on the single day of peak spring snowmelt in April. In contrast, the maximum daily export in the second year, when peak stream flow was somewhat lower, was 3.5 mg ha-1 during a January thaw. The fate of file Hg retained by this forested catchment is not known. Dissolved (< 0.22 ??m) Hg concentrations in stream water ranged from 0.5-2.6 ng L-1, even when total (unfiltered) concentrations were greater than 10 ng L-1 during high flow events. Total Hg concentrations in stream water were correlated with the total organic fraction of suspended sediment, suggesting the importance of organic material in Hg transport within the catchment. High flow events and transport with organic material may be especially important mechanisms for the movement of Hg through forested ecosystems.

  13. Fate of organic contaminants in a boreal forest catchment

    NASA Astrophysics Data System (ADS)

    Bergknut, Magnus; Meijer, Sandra; Halsall, Crispin; Ågren, Anneli; Laudon, Hjalmar; Köhler, Stephan; Jones, Kevin; Tysklind, Mats; Wiberg, Karin

    2010-05-01

    The aim of the study was to investigate and predict the impact of hydrological and atmospheric processes on the mobilisation of contaminants in a remote catchment where the major input is related to diffuse pollution. The project included priory substances according to the European water framework directive (WFD), such as the persistent organic pollutants (POPs) HCB, PCBs and dioxins. The study was conducted at a well-characterised catchment system in northern Sweden dominated by two landscape types: forest and mire. Chemical analyses of POPs in forest soil and mire peat at various depths were performed. Evaluation of POP composition by principal component analysis (PCA) showed distinct differences between surface and deeper samples. This was attributed to vertical transport, degradation and/or shifting sources over time. The calculated net vertical transport differed between surface (0.3% of the pollutant reservoir) and deeper soils (8.0 %), suggesting that vertical transport conditions and processes differ in the deeper layers compared to the surface layers.The fate of POPs in soils and waters was explored through the development of a chemical fate model. The northerly location of the studied catchment enabled a study on the impact of spring snow melt and associated hydrological processes on contaminant mobilization. Input was based on bulk atmospheric deposition and was dominated by accumulation in the winter snowpack. The model considered air-soil exchange and accumulation in forest and mire soil as well as export of dissolved and particle-bound POPs from soil to catchment surface water. The predicted export of POPs to catchment surface waters was up to 40 times higher the during snow melt period (three week during April/May) compared to the snow covered period (approximately 4 months), highlighting the importance of the seasonal snow pack as a source of these chemicals. Release from soils was governed by the POP concentration in soil, the fraction of soil

  14. Export of arsenic from forested catchments under easing atmospheric pollution

    SciTech Connect

    Lucie Erbanova; Martin Novak; Daniela Fottova; Barbora Dousova

    2008-10-01

    Massive lignite burning in Central European power plants peaked in the 1980s. Dissolved arsenic in runoff from upland forest ecosystems is one of the ecotoxicological risks resulting from power plant emissions. Maxima in As concentrations in runoff from four forest catchments have increased 2-5 times between 1995 and 2006, and approach the drinking water limit (10 {mu}g L{sup -1}). To assess the fate of anthropogenic As, we constructed input/output mass balances for three polluted and one relatively unpolluted forest catchment in the Czech Republic, and evaluated the pool size of soil As. The observation period was 11 years, and the sites spanned a 6-fold As pollution gradient. Two of the polluted sites exhibit large net As export via runoff solutes (mean of 4-5 g As ha{sup -1} yr{sup -1} for the 11-year period; up to 28 g As ha{sup -1} yr{sup -1} in 2005). This contrasts with previous studies which concluded that forest catchments are a net sink for atmogenic arsenic both at times of increasing and decreasing pollution. The amount of exported As is not correlated with the total As soil pool size, which is over 78% geogenic in origin, but correlates closely with water fluxes via runoff. Net arsenic release is caused by an interplay of hydrological conditions and retreating acidification which may mobilize arsenic by competitive ligand exchange. The effects of droughts and other aspects of climate change on subsequent As release from soil were not investigated. Between-site comparisons indicate that most pollutant As may be released from humus. 24 refs., 7 figs., 1 tab.

  15. The hydrological regime of a forested tropical Andean catchment

    NASA Astrophysics Data System (ADS)

    Clark, K. E.; Torres, M. A.; West, A. J.; Hilton, R. G.; New, M.; Horwath, A. B.; Fisher, J. B.; Rapp, J. M.; Robles Caceres, A.; Malhi, Y.

    2014-12-01

    The hydrology of tropical mountain catchments plays a central role in ecological function, geochemical and biogeochemical cycles, erosion and sediment production, and water supply in globally important environments. There have been few studies quantifying the seasonal and annual water budgets in the montane tropics, particularly in cloud forests. We investigated the water balance and hydrologic regime of the Kosñipata catchment (basin area: 164.4 km2) over the period 2010-2011. The catchment spans over 2500 m in elevation in the eastern Peruvian Andes and is dominated by tropical montane cloud forest with some high-elevation puna grasslands. Catchment-wide rainfall was 3112 ± 414 mm yr-1, calculated by calibrating Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall with rainfall data from nine meteorological stations in the catchment. Cloud water input to streamflow was 316 ± 116 mm yr-1 (9.2% of total inputs), calculated from an isotopic mixing model using deuterium excess (Dxs) and δD of waters. Field streamflow was measured in 2010 by recording height and calibrating to discharge. River run-off was estimated to be 2796 ± 126 mm yr-1. Actual evapotranspiration (AET) was 688 ± 138 mm yr-1, determined using the Priestley and Taylor-Jet Propulsion Laboratory (PT-JPL) model. The overall water budget was balanced within 1.6 ± 13.7%. Relationships between monthly rainfall and river run-off follow an anticlockwise hysteresis through the year, with a persistence of high run-off after the end of the wet season. The size of the soil and shallow groundwater reservoir is most likely insufficient to explain sustained dry-season flow. Thus, the observed hysteresis in rainfall-run-off relationships is best explained by sustained groundwater flow in the dry season, which is consistent with the water isotope results that suggest persistent wet-season sources to streamflow throughout the year. These results demonstrate the importance of transient groundwater storage in

  16. Stormflow generation: A meta-analysis of field evidence from small, forested catchments

    NASA Astrophysics Data System (ADS)

    Barthold, Frauke K.; Woods, Ross A.

    2015-05-01

    Combinations of runoff characteristics are commonly used to represent distinct conceptual models of stormflow generation. In this study, three runoff characteristics: hydrograph response, time source of runoff water, and flow path are used to classify catchments. Published data from the scientific literature are used to provide evidence from small, forested catchments. Each catchment was assigned to one of the eight conceptual models, depending on the combination of quick/slow response, old/new water, and overland/subsurface flow. A standard procedure was developed to objectively diagnose the predominant conceptual model of stormflow generation for each catchment and assess its temporal and spatial support. The literature survey yielded 42 catchments, of which 30 catchments provide a complete set of qualitative runoff characteristics resulting in one of the eight conceptual models. The majority of these catchments classify as subsurface flow path dominated. No catchments were found for conceptual models representing combinations of quick response-new water-subsurface flow (SSF), slow-new-SSF, slow-old-overland flow (OF) nor new-slow-OF. Of the 30 qualitatively classified catchments, 24 provide a complete set of quantitative measures. In summary, the field support is strong for 19 subsurface-dominated catchments and is weak for 5 surface flow path dominated catchments (six catchments had insufficient quantitative data). Two alternative explanations exist for the imbalance of field support between the two flow path classes: (1) the selection of research catchments in past field studies was mainly to explain quick hydrograph response in subsurface dominated catchments; (2) catchments with prevailing subsurface flow paths are more common in nature. We conclude that the selection of research catchments needs to cover a wider variety of environmental conditions which should lead to a broader, and more widely applicable, spectrum of resulting conceptual models and process

  17. Effects of nitrogen with and without acidified sulphur on an ectomycorrhizal community in a Sitka spruce (Picea sitchensis Bong. Carr) forest.

    PubMed

    Carfrae, J A; Skene, K R; Sheppard, L J; Ingleby, K; Crossley, A

    2006-05-01

    This preliminary study investigated the effects of enhanced nitrogen (NH4NO3 at 48 kg ha(-1) y(-1)), sulphur (Na2SO4 at 50 kg ha(-1) y(-1)), acidified nitrogen and sulphur (H2SO4 + NH4NO3) at pre-stated doses (pH 2.5), and acidified nitrogen and sulphur deposition at double these doses on the ectomycorrhizal community associated with a 13-year-old Sitka spruce (Picea sitchensis) forest. Sulphur deposition had little impact on below ground ectomycorrhizal diversity, but stimulated sporocarp production. Nitrogen inputs increased below ground colonisation compared to acidified nitrogen and sulphur, largely due to an increase in Tylospora fibrillosa colonisation. Sporocarp production and ectomycorrhizal root colonisation by Lactarius rufus were reduced in the nitrogen treated plots. These observations suggest that nitrogen deposition to a young plantation may suppress ectomycorrhizal fungi producing large sporocarps. It is proposed that enhanced nitrogen deposition increases ectomycorrhizal nitrogen assimilation, consuming more carbon and leaving less for extrametrical mycelium and sporocarp development. PMID:16246472

  18. Peak Flow Responses and Recession Flow Characteristics After Thinning of Japanese Cypress Forest in a Headwater Catchment

    EPA Science Inventory

    We evaluated the effects of forest thinning on peak flow and recession characteristics of storm runoff in headwater catchments at Mie Prefecture, Japan. In catchment M5, 58.3% of stems were removed, whereas catchment M4 remained untreated as a control catchment. Storm precipitati...

  19. Effects of harvest on carbon and nitrogen dynamics in a Pacific Northwest forest catchment

    EPA Science Inventory

    We used a new ecohydrological model, Visualizing Ecosystems for Land Management Assessments (VELMA), to analyze the effects of forest harvest on catchment carbon and nitrogen dynamics. We applied the model to a 10 ha headwater catchment in the western Oregon Cascade Range where t...

  20. Quantifying soil and critical zone variability in a forested catchment through digital soil mapping

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying catchment scale soil property variation yields insights into critical zone evolution and function. The objective of this study was to quantify and predict the spatial distribution of soil properties within a high elevation forested catchment in southern AZ, USA using a combined set of di...

  1. Temporal variation of aqueous-extractable Ca, Mg and K in acidified forest mountainous soils under different vegetation cover

    NASA Astrophysics Data System (ADS)

    Tejnecky, V.; Bradová, M.; Boruvka, L.; Vasat, R.; Nemecek, K.; Ash, C.; Sebek, O.; Rejzek, J.; Drabek, O.

    2012-12-01

    Acidification of forest soils is a natural degradation process which can be significantly enhanced by anthropogenic activities. Inputs of basic cations (BC - Ca, Mg and K) via precipitation, litter and soil organic matter decomposition and also via inter-soil weathering may partially mitigate the consequences of this degradation process. The aim of this study is to assess the temporal variation of aqueous-extractable Ca, Mg and K in acidified forest mountainous soils under different vegetation cover. The Jizera Mountains region (Czech Republic, northern Bohemia) was chosen as a representative soil mountainous ecosystem strongly affected by acidification. Soil and precipitation samples were collected at monthly basis from April till October/ November during the years 2009-2011. Study spots were delimited under two contrasting vegetation covers - beech and spruce monoculture. Prevailing soil types were classified as Alumic Cambisols under beech and Entic Podzols under spruce stands (according to FAO classification). Soil samples were collected from surface fermentation (F) and humified (H) organic horizons and subsurface B horizons (cambic or spodic). The collected soil samples were analyzed immediately under laboratory condition in a "fresh" state. Unsieved fresh samples were extracted by deionised water. The content of main elements (Ca, Mg, K, Al and Fe) was determined by ICP-OES. The content of major anions (SO42-, NO3-, Cl- and F-) was determined by ion-exchange chromatography (IC). Content of major anions and main elements were determined in the precipitation samples (throughfall, stemflow and bulk) as well. Besides computing the basic statistical parameters (mean, median, variance, maximum, minimum, etc.) we also employed other statistical methods such as T-test and ANOVA to assess the differences between beech and spruce vegetation spots. To carry out the temporal variability in the data we used the time series analysis and short-term forecasting by Holt

  2. Effects of Sloped Terrain and Forest Stand Maturity on Evapotranspiration in a Boreal Forested Catchment

    NASA Astrophysics Data System (ADS)

    Isabelle, P. E.; Nadeau, D.; Parent, A. C.; Rousseau, A. N.; Jutras, S.; Anctil, F.

    2015-12-01

    The boreal forests are the predominant landscape of Canada, occupying 49% of its boreal zone or 27% of the country. Despite the tremendous amount of literature on such ecosystems, some gaps persist in our understanding of boreal forest evapotranspiration (ET), given that direct measurements are costly to obtain and therefore scarce in these remote territories. This is especially the case on sloped terrain, since the eddy covariance method is not traditionally used in such situations. These gaps lead to the implementation of the EVAP experimental project, which intends to produce a major leap in our understanding of the water and energy budgets of a sloped boreal forest. Starting in summer 2015, we heavily instrumented a watershed in the Montmorency Forest (47°17' N; 71°10' W), Quebec, Canada. Located in the Laurentian Mountains, the forest has a mean elevation of 750 m with peaks at 1000 m. The setup includes a 20-m flux tower with two separate sets of eddy correlation and net radiation measurements facing opposite directions, located over an almost mature boreal forest (logged ~20 years ago, 8-10 m trees). Eddy fluxes are also measured under the canopy with a similar setup, while a sub-watershed is instrumented with a 10-m flux tower using homologous instruments, this time on a much younger forest stand (logged ~10 years ago, 4-5 m trees). Both sites are characterized by a significant slope (~20%), facing northeast for the 20-m tower and west for the 10-m tower. With several other instruments, we are measuring every major components of both water and energy budgets, including the outgoing discharge of the watershed and subwatershed. The different slope orientations and local topography of both sites allow us to quantify the relationships between solar exposition, topographic shading and ET rates; these relationships being transposable to other mountainous forested catchments. We also investigate the presence of slope flows and assess their impact on local ET

  3. Evapotranspiration following wildfire in resprouting eucalypt forests: from leaf to catchment

    NASA Astrophysics Data System (ADS)

    Nolan, Rachael; Lane, Patrick; Benyon, Richard; Bradstock, Ross; Mitchell, Patrick

    2014-05-01

    Forests which recover from disturbance predominately via vegetative resprouting may be expected to have different catchment water balance dynamics following wildfire than forests recovering from seed. However, the impacts of wildfire on evapotranspiration (Et) are largely unknown in resprouting forest types. This is despite their dominance across the majority of southern Australia's forested catchments and the large areas burnt in recent years. Following wildfires in south-eastern Australia in 2006 and 2009, we monitored Et over two years using a combination of sapflow, rainfall interception and forest floor Et methods. We also measured changes in forest structure and leaf physiology. We found that fire initially reduced Et, but this recovered rapidly and even increased above rates observed in unburnt forest. Post-fire changes in Et were dependent on fire severity with higher rates only observed in forest burnt at moderate severity (<70% canopy scorch). Measurements of leaf physiology indicated higher rates of stomatal conductance in seedlings, and to a lesser extent in resprouting epicormic leaves, which may be driving higher rates of water use per unit leaf area in regenerating forest compared to unburnt forest. We also found higher leaf area index in burnt forest over 2-3 years post-fire. These results demonstrate that resprouting forest types have a relatively rapid recovery of Et due to both leaf-scale physiological processes and recovery of stand-scale leaf area. These plot-scale observations of Et were compared with changes in streamflow measured from a catchment burnt mostly at moderate severity in 2006. Time-trend analysis on pre- and post-fire streamflow found that mean annual water yield reduced by an average 197 mm over 1-4 years post-fire. This was attributed to both drought, which was estimated to account for 54% of reductions, and increased Et across the catchment following fire, which is consistent with plot-scale observations.

  4. Forest management effects on snow, runoff and evapotranspiration in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Ray, R. L.; Saksa, P. C.; Bales, R. C.; Conklin, M. H.

    2012-12-01

    We used intensive field measurements and data-intensive hydro-ecological modeling to investigate the impact of forest vegetation management on the sensitivity of snow accumulation, evapotranspiration and discharge at seven headwater catchments in the Sierra Nevada. Catchments are located in dense mixed-conifer forest, at elevations of 1500 - 2100 m, and receive a mix of rain and snow precipitation. Management scenarios for reducing forest density by uniform thinning and forest clearings were implemented in the Regional Hydro-ecological Simulation System (RHESSys). Results obtained using inherent model equations to separate total precipitation into snow and rain underestimated snow water content in some of the catchments, requiring manual input of snow and rain for accurate simulations. Modeling precipitation phase accurately was critical for the current forest condition, as the change in vegetation has differing effects on rain, snow and snowmelt. Results using RHESSys show that light, uniform thinning alone (<20% canopy) may not be enough to change water yield significantly, but this threshold of canopy reduction is lowered by creating gaps in the forest alone or in combination with uniform thinning, and has potential to measurably increase water yield beyond background variation. Clarifying these specific impacts of forest vegetation on snow processes and water yield is essential for simulating forest management in the Sierra Nevada and it shows the forest structure has significant influence on the catchment water balance. However, modifying forest canopy density and canopy cover to calculate average levels of snow water equivalent at a basin-scale may not be detailed enough to incorporate all the complex forest structure effects on snow processes in mountain watersheds.

  5. Water flow paths in a forested catchment of the East Asian monsoon region

    NASA Astrophysics Data System (ADS)

    Payeur-Poirier, Jean-Lionel; Hopp, Luisa; Peiffer, Stefan

    2015-04-01

    The climate of South Korea is strongly influenced by the East Asian summer monsoon. It is hypothesized that the high precipitation regime of the summer monsoon causes significant changes in the hydrological behaviour of forested catchments, namely in water quantity, quality and flow paths. We conducted high frequency hydrometric, isotopic, hydrochemical and meteorological measurements in a forested catchment before, during and after the 2013 summer monsoon season. The catchment is located within the Lake Soyang watershed, where recent trends of increasing eutrophication, sediment load and organic carbon load have been observed. We studied the temporal variability of catchment runoff and the spatial and temporal variability of water flow paths in relation with the hydrological conditions of the hillslope, toeslope and riparian elements of the catchment. For the summer monsoon season, the runoff coefficient approximated 68%. During this period, for the 16 monitored individual storm events ranging between 13 mm and 126 mm in precipitation, the runoff coefficient greatly varied and a threshold relationship with soil moisture was observed. Analyses of hysteresis loops of catchment runoff also revealed threshold relationships with precipitation and soil moisture, as water flow paths were activated or not in different parts of the catchment. The variation of the electrical conductivity of catchment runoff through the summer monsoon also revealed the occurrence of threshold relationships. A principal component analysis (PCA) and an end-member mixing analysis (EMMA) were performed in order to quantify the contribution of the different landscape elements to catchment runoff. The combination of the hydrometric, isotopic and hydrochemical approaches allowed us to test our hypothesis and to shed light on the threshold relationships observed at the catchment. The findings of this study could be useful for the estimation of the water balance of the Lake Soyang watershed as well

  6. Impact of bushfire and climate variability on streamflow from forested catchments in southeast Australia

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Zhang, Y.; Vaze, J.; Lane, P.; Xu, S.

    2013-04-01

    Most of the surface water for natural environmental and human water uses in southeast Australia is sourced from forested catchments located in the higher rainfall areas. Water yield of these catchments is mainly affected by climatic conditions, but it is also greatly affected by vegetation cover change. Bushfires are a major natural disturbance in forested catchments and potentially modify the water yield of the catchments through changes to evapotranspiration (ET), interception and soil moisture storage. This paper quantifies the impacts of bushfire and climate variability on streamflow from three southeast Australian catchments where Ash Wednesday bushfires occurred in February 1983. The hydrological models used here include AWRA-L, Xinanjiang and GR4J. The three models are first calibrated against streamflow data from the pre-bushfire period and they are used to simulate runoff for the post-bushfire period with the calibrated parameters. The difference between the observed and model simulated runoff for the post-bushfire period provides an estimate of the impact of bushfire on streamflow. The hydrological modelling results for the three catchments indicate that there is a substantial increase in streamflow in the first 15 yr after the 1983 bushfires. The increase in streamflow is attributed to initial decreases in ET and interception resulting from the fires, followed by logging activity. After 15 yr, streamflow dynamics are more heavily influenced by climate effects, although some impact from fire and logging regeneration may still occur. It is shown that hydrological models provide reasonable consistent estimates of forest disturbance and climate impacts on streamflow for the three catchments. The results might be used by forest managers to understand the relationship between forest disturbance and climate variability impacts on water yield in the context of climate change.

  7. Connectivity of overland flow by drainage network expansion in a rain forest catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, Beate; Zimmermann, Alexander; Turner, Benjamin L.; Francke, Till; Elsenbeer, Helmut

    2014-02-01

    Soils in various places of the Panama Canal Watershed feature a low saturated hydraulic conductivity (Ks) at shallow depth, which promotes overland-flow generation and associated flashy catchment responses. In undisturbed forests of these areas, overland flow is concentrated in flow lines that extend the channel network and provide hydrological connectivity between hillslopes and streams. To understand the dynamics of overland-flow connectivity, as well as the impact of connectivity on catchment response, we studied an undisturbed headwater catchment by monitoring overland-flow occurrence in all flow lines and discharge, suspended sediment, and total phosphorus at the catchment outlet. We find that connectivity is strongly influenced by seasonal variation in antecedent wetness and can develop even under light rainfall conditions. Connectivity increased rapidly as rainfall frequency increased, eventually leading to full connectivity and surficial drainage of entire hillslopes. Connectivity was nonlinearly related to catchment response. However, additional information on factors such as overland-flow volume would be required to constrain relationships between connectivity, stormflow, and the export of suspended sediment and phosphorus. The effort to monitor those factors would be substantial, so we advocate applying the established links between rain event characteristics, drainage network expansion by flow lines, and catchment response for predictive modeling and catchment classification in forests of the Panama Canal Watershed and in similar regions elsewhere.

  8. Flowpaths, source water contributions and water residence times in a Mexican tropical dry forest catchment

    NASA Astrophysics Data System (ADS)

    Farrick, Kegan K.; Branfireun, Brian A.

    2015-10-01

    Runoff in forested tropical catchments has been frequently described in the literature as dominated by the rapid translation of rainfall to runoff through surface and shallow subsurface pathways. However, studies examining runoff generation in tropical catchments with highly permeable soils have received little attention, particularly in tropical dry forests. We present a study focused on identifying the dominant flowpaths, water sources and stream water residence times in a tropical dry forest catchment near the Pacific coast of central Mexico. During the wet season, pre-event water contributions to stormflow ranged from 72% to 97%, with the concentrations of calcium, magnesium, sodium and potassium closely coupling the geochemistry of baseflow and groundwater from the narrow riparian/near-stream zone. Baseflow from the intermittent stream showed a strongly damped isotopic signature and a mean baseflow residence time of 52-110 days was estimated. These findings all suggest that instead of the surface and near-surface subsurface lateral pathways observed over many tropical catchments, runoff is generated through vertical flow processes and the displacement and discharge of stored water from the saturated zone. As the wet season progressed, contributions from the saturated zone persisted; however, the stormflow and baseflow geochemistry suggests that the contributing area of the catchment increased. Our results show that during the early part of the wet season, runoff originated primarily from the headwater portion of the catchment. As the wet season progressed and catchment wetness increased, connectivity among sub-basin was improved, resulting in runoff contributions from across the entire catchment.

  9. Multi-scale linkages between forest water use, catchment storage, and streamflow dynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Hale, C.; McDonnell, J. J.

    2010-12-01

    Forests exert an explicit control on streamflow dynamics through their use of water stored within the catchment. While the connection between stored water and stream discharge dynamics has been studied for decades, forest hydrologists continue to struggle to understand how trees modulate these fluxes on timescales of hours to years. Here we present new data from the Alsea experimental forest in Western Oregon that examines coupled ecohydrological processes from tree to headwater catchment scales. We combine experimental forest removal and water isotope (18O and 2H) analysis of tree source water with more traditional hydrometric measurements and analysis (stream gauging and groundwater hydrology) to probe forest-catchment coupling mechanisms. Preliminary results show that removal of riparian zone Douglas-fir and red alder forest from first-order channels had no discernable effect on diel fluctuations in stream discharge. In contrast to this tightly coupled behavior, analysis of precipitation and stream water isotope signals (weekly sampling) indicate that the mean transit time of our stream water is in excess of 2.5 years. In between the extremes of diel streamflow fluctuations and multi-annual particle flux through the subsurface, water levels in shallow (5-8 m depth) and deep (37 m) fractured bedrock groundwater systems show evidence of storm rainfall response, but only after a storage deficit has been met through the course of the Pacific Northwest’s seasonal wetting cycle. Once activated, event-based groundwater level response was as much as 0.5 m and typically lagged the precipitation center of mass on the order of minutes to hours. During the same wetting period, streamflow runoff ratios increased from 1-5% under dry catchment conditions and plateaued at 65-85% when events occurred during moderately wet to very wet catchment conditions. Overall, our results suggest that while forests modulate small daily fluctuations in summer baseflow, they also set the

  10. Catchment hydro-biogeochemical response to forest harvest intensity and spatial pattern

    EPA Science Inventory

    We apply a new model, Visualizing Ecosystems for Land Management Assessment (VELMA), to Watershed 10 (WS10) in the H.J. Andrews Experimental Forest to simulate the effects of harvest intensity and spatial pattern on catchment hydrological and biogeochemical processes. Specificall...

  11. Catchment hydrological responses to forest harvest amount and spatial pattern - 2011

    EPA Science Inventory

    We used an ecohydrological model, Visualizing Ecosystems for Land Management Assessments (VELMA), to analyze the effects of forest harvest location and amount on ecosystem carbon (C) and nitrogen (N) dynamics in an intensively studied headwater catchment (WS10) in western Oregon,...

  12. Controls on Mercury Transport from Forested Headwater Catchments in Shenandoah National Park and Beyond

    NASA Astrophysics Data System (ADS)

    Scanlon, T. M.; Riscassi, A.

    2012-12-01

    Mercury is exported from forested watersheds primarily during storms events, the consequence of hydrological transport through shallow subsurface and surface pathways and the mobilization of in-stream sediment. Our sampling efforts focused on high-flow events within three forested headwater catchments in Shenandoah National Park over the course of a full year using an automated sampling procedure. The dissolved and particulate forms of mercury exhibit distinct transport characteristics, with the former influenced primarily by dissolved organic carbon quantity and quality and the latter driven by suspended sediment concentrations, with more pronounced hysteresis. The amount of mercury export from the three forested catchments is compared with estimates from other systems, as is the "enrichment" factor of dissolved mercury per unit dissolved organic carbon. We speculate as to why this enrichment factor tends to be higher for systems with smaller pools of soil organic matter. Distributed measurements of soil mercury concentrations within a catchment show that elevation also plays a role in influencing the amount of mercury stored within the organic soil horizon. Continued efforts to quantify dry deposition are also presented, which has implications for better constraining the mercury budgets of forested catchments.

  13. Comparing Hydrologic Response Times Between a Forested and Mountaintop Mined Catchment

    NASA Astrophysics Data System (ADS)

    Miller, A. J.; Zegre, N.

    2012-12-01

    Mountaintop removal mining (MTR) represents the largest land cover/landuse change in the Central Appalachian region. By 2012, the U.S. EPA estimates that MTR will have impacted approximately 6.8% of the predominately forested Appalachian Coalfield region of West Virginia, Kentucky, Tennessee, and Virginia with nearly 4,000 miles of headwater streams buried under valley fills. In spite of the scale and extent of MTR, its hydrologic impacts are poorly understood. While MTR has a well-established pattern of downstream water quality degradation, its effect on the quantity and timing of catchment runoff is less clear. Several devastating floods in the region have been attributed to MTR, but there is little evidence to either confirm or refute this belief. Existing research has focused on statistical analysis of catchment outlet responses, but results from these studies only offer evidence of differences in hydrologic behavior, not process understanding of how the system is changing. This study begins to address that research gap by exploring differences in hydrologic response times, a fundamental hydraulic parameter that controls the conversion of rainfall to runoff. A simple rainfall-runoff model was used to quantify differences in response times for storm events in a mined and predominantly forested catchment. Results showed that the mountaintop mined catchment responded more quickly to storm events than the forested catchment. The mined catchment also showed more variability in response time than the forested catchment. These patterns repeated using multiple model structures. The more rapid response of the mined catchment is likely attributed to increased impervious surface, preferential flow paths within valley fills that rapidly route water to the stream, or rapid displacement of water stored in valley fills upon the onset of rain. However, further research using tools such as isotope tracers is needed to offer insight about the processes responsible for streamflow

  14. Geomorphic controls on the export of dissolved organic carbon from forested catchments in central Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Creed, I. F.; Lynch, M. D.; Sanford, S. E.; Beall, F. D.; Jeffries, D. S.

    2001-12-01

    Dissolved organic carbon (DOC) is a complex mixture of hydrophobic and hydrophilic compounds that has significant implications for the quality of surface water. In forests, wetlands have been shown to be a significant source of the natural variation in DOC export to streams; however, ephemeral wetlands (or surface saturated areas, SSAs) have not yet been considered as a potential source. For catchments in the Turkey Lakes Watershed (TLW) in central Ontario, Canada, the natural variation in DOC export was established and a statistical model to predict this natural variation was developed. For 12 catchments in the TLW, the natural variation in DOC export was significant, with annual averages ranging from 13.8 to 23.2 kg Chayr and catchment averages ranging from 11.9 to 31.5 kg Chayr. It was hypothesised that geomorphic controls on the distribution and organisation of SSAs within catchments influence DOC export. Three SSA indices were derived: (1) SSA size; (2) SSA connectivity to streams (reflecting the hydrologic efficiency of DOC transport); and (3) SSA curvature (reflecting the potential for hydrologic flushing into areas of replenished DOC sources). A multiple linear model indicated that the majority of the natural variation in DOC export was explained by a combination of the hydrologic efficiency and flushing potentials of the SSAs (R-sqr.=0.717, Adjusted R-sqr.4=0.654, p<0.05). To improve predictions of DOC export from forested catchments, the role of both permanent and ephemeral wetlands must be considered.

  15. Isotopic signals of summer denitrification in a northern hardwood forested catchment

    PubMed Central

    Wexler, Sarah K.; Goodale, Christine L.; Bailey, Scott W.; Groffman, Peter M.

    2014-01-01

    Despite decades of measurements, the nitrogen balance of temperate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ15NNO3 and δ18ONO3) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments. PMID:25368188

  16. Isotopic signals of summer denitrification in a northern hardwood forested catchment.

    PubMed

    Wexler, Sarah K; Goodale, Christine L; McGuire, Kevin J; Bailey, Scott W; Groffman, Peter M

    2014-11-18

    Despite decades of measurements, the nitrogen balance of temperate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ(15)NNO3 and δ(18)ONO3) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments. PMID:25368188

  17. Effects of a rainstorm high in sea-salts on labile inorganic aluminium in drainage from the acidified catchments of Lake Terjevann, southernmost Norway

    NASA Astrophysics Data System (ADS)

    Andersen, D. O.; Seip, H. M.

    1999-10-01

    The acidification of many streams and lakes that has occurred in southern Norway during several decades is to a large extent caused by acid deposition. However, in coastal areas deposition events with high loading of sea-salts may result in increased acidity and aluminium concentration in the discharge. Since such episodes are difficult to predict and usually of short duration, the aluminium chemistry during such episodes has so far not been evaluated in detail. In January 1993, during monitoring of streams in the Lake Terjevann catchment, the area was exposed to an extraordinary high sea-salt loading. The Cl - concentration in the stream water more than doubled (reaching about 900 μeq/l), the labile inorganic aluminium (Al i) concentration almost quadrupled (reaching about 33 and 18 μM in the two streams), and the relative increase in the Al 3+ concentration was even higher. It took 3-4 months until the Al i concentration and almost a year until the Cl - concentration returned to pre-event levels. Simple equilibria with minerals such as gibbsite, jurbanite, kaolinite/halloysite or imogolite do not control aluminium concentration in the discharge from these catchments. Retention of Na + more than compensated for the desorption of Al 3+. The results strongly indicate that cation exchange in the organic soil layers was essential in controlling the aluminium chemistry in the stream waters especially during high flow. Similar, but less pronounced, effects of the sea-salt episode were seen at the Birkenes catchment about 37 km inland from Lake Terjevann.

  18. The hydrological behaviour of a forested catchment during two contrasting summer monsoon seasons

    NASA Astrophysics Data System (ADS)

    Payeur-Poirier, Jean-Lionel; Hopp, Luisa; Peiffer, Stefan

    2015-04-01

    The climate of South Korea is strongly influenced by the East Asian summer monsoon. It is hypothesized that the high precipitation regime of the summer monsoon causes significant changes in the hydrological behaviour of forested catchments, namely in water quantity, quality and flow paths. We conducted high frequency hydrometric, isotopic, hydrochemical and meteorological measurements in a forested catchment before, during and after two contrasting summer monsoon seasons. The catchment is located within the Lake Soyang watershed, where recent trends of increasing eutrophication, sediment load and organic carbon load have been observed. We studied the temporal variability of catchment runoff in relation with the spatial and temporal variability of water flow paths. The 2013 and 2014 summer monsoon seasons were, respectively, the longest and shortest that occurred in this region since 1973 and accounted for 206% and 32% of the average precipitation for the summer monsoon since 1973. For the period from June through August, the precipitation of 2014 was the lowest on record since 1973. Catchment runoff for the summer monsoon totalled 559 mm and 12 mm for 2013 and 2014, respectively. The Q50 of the flow duration curve for 2014 was more than four times lower than that for 2013. A total of 18 storm events were monitored, ranging between 13 mm and 126 mm in precipitation. A principal component analysis (PCA) and an end-member mixing analysis (EMMA) were performed in order to quantify the contribution of different end-members to catchment runoff and highlight the differences between both years. The combination of the hydrometric, isotopic and hydrochemical approaches allowed us to test our hypothesis and to shed light on the hydrological behaviour of the catchment under contrasting environmental conditions. The findings of this study could be useful for the estimation of the water balance of the Lake Soyang watershed as well as for the management of Lake Soyang.

  19. Factors controlling nitrogen release from two forested catchments with contrasting hydrochemical responses

    USGS Publications Warehouse

    Christopher, S.F.; Mitchell, M.J.; McHale, M.R.; Boyer, E.W.; Burns, Douglas A.; Kendall, C.

    2008-01-01

    Quantifying biogeochemical cycles of nitrogen (N) and the associated fluxes to surface waters remains challenging, given the need to deal with spatial and temporal variability and to characterize complex and heterogeneous landscapes. We focused our study on catchments S14 and S15 located in the Adirondack Mountains of New York, USA, which have similar topographic and hydrologic characteristics but contrasting stream nitrate (NO3- ) concentrations. We characterized the mechanisms by which NO3- reaches the streams during hydrological events in these catchments, aiming to reconcile our field data with our conceptual model of factors that regulate nutrient exports from forested catchments. Combined hydrometric, chemical and isotopic (??18O-H2O) data showed that the relative contributions of both soil and ground water sources were similar between the two catchments. Temporal patterns of stream chemistry were markedly different between S14 and S15, however, because the water sources in the two catchments have different solute concentrations. During late summer/fall, the largest source of NO3- in S14 was till groundwater, whereas shallow soil was the largest NO3- source in S15. NO3- concentrations in surface water decreased in S14, whereas they increased in S15 because an increasing proportion of stream flow was derived from shallow soil sources. During snowmelt, the largest sources of NO3- were in the near-surface soil in both catchments. Concentrations of NO3- increased as stream discharge increased and usually peaked before peak discharge, when shallow soil water sources made the largest contribution to stream discharge. The timing of peaks in stream NO3- concentrations was affected by antecedent moisture conditions. By elucidating the factors that affect sources and transport of N, including differences in the soil nutrient cycling and hydrological characteristics of S14 and S15, this study contributes to the overall conceptualization of NO3- release from temperate

  20. Estimating the SCS runoff curve number in forest catchments of Korea

    NASA Astrophysics Data System (ADS)

    Choi, Hyung Tae; Kim, Jaehoon; Lim, Hong-geun

    2016-04-01

    To estimate flood runoff discharge is a very important work in design for many hydraulic structures in streams, rivers and lakes such as dams, bridges, culverts, and so on. So, many researchers have tried to develop better methods for estimating flood runoff discharge. The SCS runoff curve number is an empirical parameter determined by empirical analysis of runoff from small catchments and hillslope plots monitored by the USDA. This method is an efficient method for determining the approximate amount of runoff from a rainfall even in a particular area, and is very widely used all around the world. However, there is a quite difference between the conditions of Korea and USA in topography, geology and land use. Therefore, examinations in adaptability of the SCS runoff curve number need to raise the accuracy of runoff prediction using SCS runoff curve number method. The purpose of this study is to find the SCS runoff curve number based on the analysis of observed data from several experimental forest catchments monitored by the National Institute of Forest Science (NIFOS), as a pilot study to modify SCS runoff curve number for forest lands in Korea. Rainfall and runoff records observed in Gwangneung coniferous and broad leaves forests, Sinwol, Hwasoon, Gongju and Gyeongsan catchments were selected to analyze the variability of flood runoff coefficients during the last 5 years. This study shows that runoff curve numbers of the experimental forest catchments range from 55 to 65. SCS Runoff Curve number method is a widely used method for estimating design discharge for small ungauged watersheds. Therefore, this study can be helpful technically to estimate the discharge for forest watersheds in Korea with more accuracy.

  1. a Generic Framework for Water and Forest Management in Catchments Restoration in Latin America

    NASA Astrophysics Data System (ADS)

    Mintegui Aguirre, J. A.; Amezaga, J. M.; Robredo Sanchez, J. C.; Lopez Leiva, C.

    2007-05-01

    The document presents a generic framework for the analysis and development of a programme for catchment management and restoration that takes into account both the protection from the impact of extreme events and the sustainable use of land and water resources. The framework was originally developed for the restoration of mountain catchments in Europe between the end of the 19th century and the beginning of the 20th century and still provides the intellectual basis for the integrated assessment of hydraulic and land use factors in these countries. It is based on a thorough analysis of the behavior of a catchment in normal and extreme conditions. Recently, the authors have tested this generic framework in a number of catchments in Latin America, which present very different physical and socio-economic conditions. Fieldwork in Costa Rica, Ecuador, Chile and Argentina with particular catchments covering a whole range of climatological, geo-morphological and land used settings has provided new insights on the applicability of this generic framework. The paper discusses the role of vegetation, and in particular of forests, in catchment management taking a long-term view of cost and benefits under normal and extreme conditions. It also provides conclusions for the development of land use policies to optimize the practical use of vegetation of management purposes.

  2. Soil water storage, rainfall and runoff relationships in a tropical dry forest catchment

    NASA Astrophysics Data System (ADS)

    Farrick, Kegan K.; Branfireun, Brian A.

    2014-12-01

    In forested catchments, the exceedance of rainfall and antecedent water storage thresholds is often required for runoff generation, yet to our knowledge these threshold relationships remain undescribed in tropical dry forest catchments. We, therefore, identified the controls of streamflow activation and the timing and magnitude of runoff in a tropical dry forest catchment near the Pacific coast of central Mexico. During a 52 day transition phase from the dry to wet season, soil water movement was dominated by vertical flow which continued until a threshold soil moisture content of 26% was reached at 100 cm below the surface. This satisfied a 162 mm storage deficit and activated streamflow, likely through lateral subsurface flow pathways. High antecedent soil water conditions were maintained during the wet phase but had a weak influence on stormflow. We identified a threshold value of 289 mm of summed rainfall and antecedent soil water needed to generate >4 mm of stormflow per event. Above this threshold, stormflow response and magnitude was almost entirely governed by rainfall event characteristics and not antecedent soil moisture conditions. Our results show that over the course of the wet season in tropical dry forests the dominant controls on runoff generation changed from antecedent soil water and storage to the depth of rainfall.

  3. Effect of ditching operations on stream-water chemistry in a boreal forested catchment.

    PubMed

    Aström, M; Aaltonen, E K; Koivusaari, J

    2001-11-12

    The effects of ditching of boreal forest land on stream-water quality and quantity was assessed by comparing, over a 4-year-period, the physicochemical properties of the water in two small streams (western Finland), one whose catchment was ditched for forestry halfway through the sampling period and another nearby (control) stream whose catchment was not ditched ('paired catchment method'). While the artificial drainage did not have any significant effect on the hydrograph, it resulted in an increase in the aquatic concentrations of Mn, Ca, Mg, suspended material and alkalinity, a decrease in the concentrations of TOC and H3O+, while for Al and Fe there was a change in control mechanisms. The concentration and control changes after ditching are related to changes in hydrological pathways and to the exposure of both organic (peat) and inorganic (mineral soil) layers on the ditch slopes. PMID:11712589

  4. Predicting forested catchment evapotranspiration and streamflow from stand sapwood area and Aridity Index

    NASA Astrophysics Data System (ADS)

    Lane, Patrick

    2016-04-01

    Estimating the water balance of ungauged catchments has been the subject of decades of research. An extension of the fundamental problem of estimating the hydrology is then understanding how do changes in catchment attributes affect the water balance component? This is a particular issue in forest hydrology where vegetation exerts such a strong influence on evapotranspiration (ET), and consequent streamflow (Q). Given the primacy of trees in the water balance, and the potential for change to species and density through logging, fire, pests and diseases and drought, methods that directly relate ET/Q to vegetation structure, species, and stand density are very powerful. Plot studies on tree water use routinely use sapwood area (SA) to calculate transpiration and upscale to the stand/catchment scale. Recent work in south eastern Australian forests have found stand-wide SA to be linearly correlated (R2 = 0.89) with long term mean annual loss (P-Q), and hence, long term mean annual catchment streamflow. Robust relationships can be built between basal area (BA), tree density and stand SA. BA and density are common forest inventory measurements. Until now, no research has related the fundamental stand attribute of SA to streamflow. The data sets include catchments that have been thinned and with varying age classes. Thus far these analyses have been for energy limited systems in wetter forest types. SA has proven to be a more robust biometric than leaf area index which varies seasonally. That long term ET/Q is correlated with vegetation conforms to the Budyko framework. Use of a downscaled (20 m) Aridity Index (AI) has shown distinct correlations with stand SA, and therefore T. Structural patterns at a the hillslope scale not only correlate with SA and T, but also with interception (I) and forest floor evaporation (Es). These correlations between AI and I and Es have given R2 > 0.8. The result of these studies suggest an ability to estimate mean annual ET fluxes at sub

  5. Catchment hydrological responses to forest harvest amount and spatial pattern

    EPA Science Inventory

    Forest harvest effects on streamflow dynamics have been well described experimentally, but a clear understanding of process-level hydrological controls can be difficult to ascertain from data alone. We apply a new model, Visualizing Ecosystems for Land Management Assessments (VE...

  6. A simple model of stream nitrate concentrations in forested and deforested catchments in Mid-Wales

    NASA Astrophysics Data System (ADS)

    Sloan, William T.; Jenkins, Alan; Eatherall, Andrew

    1994-06-01

    A model is developed specifically for simulating the nitrate concentrations in a stream at approximately weekly intervals in an upland forested and a moorland catchment. It is constructed on the basis of observed nitrate concentrations in rain water and in two streams, the Hafren and the Hore, at Plynlimon, Mid-Wales, where long data records exist. The Hore catchment has recently undergone extensive deforestation. A simple regression model relating temperature to stream nitrate concentrations was capable of simulating the seasonal fluctuations in nitrate concentration observed in the Hafren. However, this ignores the influx of nitrate through wet deposition and is incapable of simulating land-use change. The regression model was developed into a simple dynamic model which includes a deposition term and a biomass indicator. The extended Kalman filter algorithm was used to estimate the optimum values of the parameters and to assess the model structure. The model was applied to both catchments, and the fit between observed and simulated nitrate concentrations at the Hafren was good. At the Hore, the model was able to capture the major changes in nitrate concentration through the deforestation and replanting phases although detailed short-term dynamics were not well represented. Finally, the model is related, speculatively, to processes which are known to occur in most catchments. This simple model is intended as a step towards the development of similar but more comprehensive catchment models of stream nitrogen dynamics.

  7. Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration

    NASA Astrophysics Data System (ADS)

    Stacy, E. M.; Hart, S. C.; Hunsaker, C. T.; Johnson, D. W.; Berhe, A. A.

    2015-08-01

    Lateral movement of organic matter (OM) due to erosion is now considered an important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet most published studies on the role of erosion focus on agricultural or grassland ecosystems. To date, little information is available on the rate and nature of OM eroded from forest ecosystems. We present annual sediment composition and yield, for water years 2005-2011, from eight catchments in the southern part of the Sierra Nevada, California. Sediment was compared to soil at three different landform positions from the source slopes to determine if there is selective transport of organic matter or different mineral particle size classes. Sediment export varied from 0.4 to 177 kg ha-1, while export of C in sediment was between 0.025 and 4.2 kg C ha-1 and export of N in sediment was between 0.001 and 0.04 kg N ha-1. Sediment yield and composition showed high interannual variation. In our study catchments, erosion laterally mobilized OM-rich litter material and topsoil, some of which enters streams owing to the catchment topography where steep slopes border stream channels. Annual lateral sediment export was positively and strongly correlated with stream discharge, while C and N concentrations were both negatively correlated with stream discharge; hence, C : N ratios were not strongly correlated to sediment yield. Our results suggest that stream discharge, more than sediment source, is a primary factor controlling the magnitude of C and N export from upland forest catchments. The OM-rich nature of eroded sediment raises important questions about the fate of the eroded OM. If a large fraction of the soil organic matter (SOM) eroded from forest ecosystems is lost during transport or after deposition, the contribution of forest ecosystems to the erosion-induced C sink is likely to be small (compared to croplands and grasslands).

  8. Modeling long-term suspended-sediment export from an undisturbed forest catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, Alexander; Francke, Till; Elsenbeer, Helmut

    2013-04-01

    Most estimates of suspended sediment yields from humid, undisturbed, and geologically stable forest environments fall within a range of 5 - 30 t km-2 a-1. These low natural erosion rates in small headwater catchments (≤ 1 km2) support the common impression that a well-developed forest cover prevents surface erosion. Interestingly, those estimates originate exclusively from areas with prevailing vertical hydrological flow paths. Forest environments dominated by (near-) surface flow paths (overland flow, pipe flow, and return flow) and a fast response to rainfall, however, are not an exceptional phenomenon, yet only very few sediment yields have been estimated for these areas. Not surprisingly, even fewer long-term (≥ 10 years) records exist. In this contribution we present our latest research which aims at quantifying long-term suspended-sediment export from an undisturbed rainforest catchment prone to frequent overland flow. A key aspect of our approach is the application of machine-learning techniques (Random Forest, Quantile Regression Forest) which allows not only the handling of non-Gaussian data, non-linear relations between predictors and response, and correlations between predictors, but also the assessment of prediction uncertainty. For the current study we provided the machine-learning algorithms exclusively with information from a high-resolution rainfall time series to reconstruct discharge and suspended sediment dynamics for a 21-year period. The significance of our results is threefold. First, our estimates clearly show that forest cover does not necessarily prevent erosion if wet antecedent conditions and large rainfalls coincide. During these situations, overland flow is widespread and sediment fluxes increase in a non-linear fashion due to the mobilization of new sediment sources. Second, our estimates indicate that annual suspended sediment yields of the undisturbed forest catchment show large fluctuations. Depending on the frequency of large

  9. Quantifying soil and critical zone variability in a forested catchment through digital soil mapping

    NASA Astrophysics Data System (ADS)

    Holleran, M.; Levi, M.; Rasmussen, C.

    2015-01-01

    Quantifying catchment-scale soil property variation yields insights into critical zone evolution and function. The objective of this study was to quantify and predict the spatial distribution of soil properties within a high-elevation forested catchment in southern Arizona, USA, using a combined set of digital soil mapping (DSM) and sampling design techniques to quantify catchment-scale soil spatial variability that would inform interpretation of soil-forming processes. The study focused on a 6 ha catchment on granitic parent materials under mixed-conifer forest, with a mean elevation of 2400 m a.s.l, mean annual temperature of 10 °C, and mean annual precipitation of ~ 85 cm yr-1. The sample design was developed using a unique combination of iterative principal component analysis (iPCA) of environmental covariates derived from remotely sensed imagery and topography, and a conditioned Latin hypercube sampling (cLHS) scheme. Samples were collected by genetic horizon from 24 soil profiles excavated to the depth of refusal and characterized for soil mineral assemblage, geochemical composition, and general soil physical and chemical properties. Soil properties were extrapolated across the entire catchment using a combination of least-squares linear regression between soil properties and selected environmental covariates, and spatial interpolation or regression residual using inverse distance weighting (IDW). Model results indicated that convergent portions of the landscape contained deeper soils, higher clay and carbon content, and greater Na mass loss relative to adjacent slopes and divergent ridgelines. The results of this study indicated that (i) the coupled application of iPCA and cLHS produced a sampling scheme that captured the greater part of catchment-scale soil variability; (ii) application of relatively simple regression models and IDW interpolation of residuals described well the variance in measured soil properties and predicted spatial correlation of soil

  10. Upland forest soils have a significant contribution to a catchment-scale CH4 balance in a wet year

    NASA Astrophysics Data System (ADS)

    Lohila, Annalea; Aalto, Tuula; Aurela, Mika; Hatakka, Juha; Tuovinen, Juha-Pekka; Kilkki, Juho; Penttilä, Timo; Vuorenmaa, Jussi; Hänninen, Pekka; Sutinen, Raimo; Viisanen, Yrjö; Laurila, Tuomas

    2016-04-01

    Upland forest soils affect the atmospheric methane (CH4) balance, not only through the soil sink, but also due to episodic high emissions in wet conditions. We measured methane fluxes in a northern boreal catchment and found that during a wet autumn the forest soil turned from a CH4 sink into a large source for several months, while the CH4 emissions from a nearby wetland did not increase. When upscaled to the whole catchment area with ca. 4/5 of the total area consisting of upland forests and the rest being wetlands, forests contributed 60% of the annual CH4 emission from the wetlands. In a normal year, the forest soil consumes 10% of the wetland emission. In a monthly scale, the autumn emissions from the upland forests were twice as high as those from wetlands within the same catchment. The period of unusually high upland soil emission was also captured by the nearby atmospheric concentration measurement station. Moreover, the monthly atmospheric CH4 anomalies in autumn were positively correlated with the water level of the lake collecting waters from the catchment. Since the land cover within our study catchment is representative of larger regions, our findings imply that upland forests in the boreal zone constitute an important part in the global CH4 cycle not previously accounted for.

  11. Soil Collembola communities within Plešné Lake and Čertovo Lake catchments, the Bohemian Forest

    NASA Astrophysics Data System (ADS)

    Čuchta, Peter

    2016-04-01

    The soil Collembola communities were studied for three years in disturbed spruce forest stands in the catchments areas of Čertovo and Plešné Lakes in the Bohemian Forest, Czech Republic. The study was focused on the impact of the windthrow, bark beetle outbreak damage and consecutive changes in the forest stands including soil environment. Four different treatments were selected for the study on both study areas: undamaged (control) forest stands, "dead" forest stands damaged by bark beetle, slightly managed windthrown forest stands left for the natural succession, and freshly harvested windthrown stands. After two years of research a total of 7,294 Collembola specimens were recorded belonging to 93 species. We recorded the highest collembolan abundance and species richness in the reference stands within catchments of both lakes, while both given parameters were considerably lower in harmed forest stands. To summarize, the disturbance led to a general decrease of Collembola communities.

  12. Importance of riparian forests in urban catchments contingent on sediment and hydrologic regimes

    USGS Publications Warehouse

    Roy, A.H.; Freeman, Mary C.; Freeman, B.J.; Wenger, S.J.; Meyer, J.L.; Ensign, W.E.

    2006-01-01

    Forested riparian corridors are thought to minimize impacts of landscape disturbance on stream ecosystems; yet, the effectiveness of streamside forests in mitigating disturbance in urbanizing catchments is unknown. We expected that riparian forests would provide minimal benefits for fish assemblages in streams that are highly impaired by sediment or hydrologic alteration. We tested this hypothesis in 30 small streams along a gradient of urban disturbance (1-65% urban land cover). Species expected to be sensitive to disturbance (i.e., fluvial specialists and "sensitive" species that respond negatively to urbanization) were best predicted by models including percent forest cover in the riparian corridor and a principal components axis describing sediment disturbance. Only sites with coarse bed sediment and low bed mobility (vs. sites with high amounts of fine sediment) had increased richness and abundances of sensitive species with higher percent riparian forests, supporting our hypothesis that response to riparian forests is contingent on the sediment regime. Abundances of Etheostoma scotti, the federally threatened Cherokee darter, were best predicted by models with single variables representing stormflow (r2 = 0.34) and sediment (r2 = 0.23) conditions. Lentic-tolerant species richness and abundance responded only to a variable representing prolonged duration of low-flow conditions. For these species, hydrologic alteration overwhelmed any influence of riparian forests on stream biota. These results suggest that, at a minimum, catchment management strategies must simultaneously address hydrologic, sediment, and riparian disturbance in order to protect all aspects of fish assemblage integrity. ?? 2006 Springer Science+Business Media, Inc.

  13. Origin of particulate organic matter exported during storm events in a forested headwater catchment.

    NASA Astrophysics Data System (ADS)

    Jeanneau, Laurent; Rowland, Richard D.; Inamdar, Shreeram P.

    2016-04-01

    Particulate organic matter (POM) plays an important biogeochemical role towards ecology, ecotoxicology and carbon cycle. Moreover POM within the fluvial suspended sediment load during infrequent high flows can comprise a larger portion of long-term flux than dissolved species. It is well documented that storm events that constituted only 10-20% of the year contributed to >80% of POC exports. But the origin and composition of POM transferred during those hot moments remained unclear. In order to improve our knowledge on this topic we explore the variability in storm event-transported sediments' POM content and source down a continuum of catchment drainage locations. Wetland, upland and forest O horizons, litter, river banks and bed sediments were analyzed for their content in organic C, isotopic (13C) and molecular (thermochemiolysis-gas chromatography-mass spectrometry) fingerprints. The isotopic and molecular fingerprints recorded in suspended and deposited (differentiated into fine, medium and coarse particles) sediments sampled during different storm events down a continuum of catchment drainage locations (12 and 79 ha). This study highlights compositional differences between the catchment size (12 versus 79 ha), the particle size of deposited sediment (fine versus medium versus coarse) and the sampling time during a storm event (rising limb versus peak flow versus falling limb). Two sampling strategies were used. Suspended sediments sampled at a specific time during flood events allow evaluating changes along the hydrograph, while deposited sediments that integrate the entire event allow making comparisons with drainage scale. For deposited sediments, the proportion of OM coming from the endmembers wetland, litter and Forest O horizon decreases from the 12ha to the 79ha catchment, which exhibited a higher proportion of OM coming from stream bed sediment and river banks. For both catchments, from fine to coarse particles, the influence of stream bed sediments

  14. One century of hydrological monitoring in two small catchments with different forest coverage.

    PubMed

    Stähli, Manfred; Badoux, Alexandre; Ludwig, Andreas; Steiner, Karl; Zappa, Massimiliano; Hegg, Christoph

    2011-03-01

    Long-term data on precipitation and runoff are essential to draw firm conclusions about the behavior and trends of hydrological catchments that may be influenced by land use and climate change. Here the longest continuous runoff records from small catchments (<1 km(2)) in Switzerland (and possibly worldwide) are reported. The history of the hydrological monitoring in the Sperbel- and Rappengraben (Emmental) is summarized, and inherent uncertainties in the data arising from the operation of the gauges are described. The runoff stations operated safely for more than 90% of the summer months when most of the major flood events occurred. Nevertheless, the absolute values of peak runoff during the largest flood events are subject to considerable uncertainty. The observed differences in average, base, and peak runoff can only partly be attributed to the substantial differences in forest coverage. This treasure trove of data can be used in various ways, exemplified here with an analysis of the generalized extreme value distributions of the two catchments. These distributions, and hence flood return periods, have varied greatly in the course of one century, influenced by the occurrence of single extreme events. The data will be made publicly available for the further analysis of the mechanisms governing the runoff behavior of small catchments, as well as for testing stochastic and deterministic models. PMID:21072587

  15. Evaluating the Impacts of Unexpected Forest Disturbances on Paired Catchment Calibrations of Sediment Yield and Turbidity

    NASA Astrophysics Data System (ADS)

    Herlein, K.; Silins, U.; Williams, C.; Wagner, M. J.; Martens, A. M.

    2015-12-01

    The paired catchment approach of studying the impacts of disturbance on catchment hydrology remains as perhaps the most powerful approach for direct verification of catchment scale impacts from disturbance. However, paired catchment studies are also dependent on the stability of the relationships between treated and reference catchments during calibration and evaluation periods. A long-term paired catchment study of forest harvest impacts on sediment yield and turbidity in the Rocky Mountains of southwestern Alberta, Canada has a robust 11-year pre-treatment data record. The study intends to evaluate three alternative logging practices: clear-cutting, strip-shelterwood, and partial cutting. 3 sub-catchments in Star Creek (1035 ha) underwent harvest treatments while North York Creek (865 Ha) serves as the reference. The objective of this particular study was to explore the potential effects of unplanned and unanticipated watershed changes in two watersheds during an 11-year calibration. Sediment yield (kg ha-1 d-1) and turbidity (NTU) were monitored throughout the calibration period (2004-2014) prior to the 2015 harvest in Star Creek. Two unanticipated disturbances including backcountry trail rehabilitation in North York (2010) followed by a >100 year storm event in both watersheds in June 2013 may have affected the sediment yield and turbidity calibration relationships. Analysis of covariance (ANCOVA) was used to evaluate the effects of this trail rehabilitation and flooding by comparing the calibration relationships before and after these disturbances. Despite qualitative field observations of periodically affected sediment regimes, no impact on pre- or post- calibration relationships was observed. Backcountry trail rehabilitation in North York (p=0.904 and 0.416 for sediment yield and turbidity, respectively) or flooding in both watersheds (p=0.364 and 0.204 for sediment yield and turbidity, respectively) did not produce significant changes to the calibrations

  16. Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration

    NASA Astrophysics Data System (ADS)

    Stacy, E.; Hart, S. C.; Hunsaker, C. T.; Johnson, D. W.; Berhe, A. A.

    2015-02-01

    Soil erosion plays important roles in organic matter (OM) storage and persistence in dynamic landscapes. The biogeochemical implication of soil erosion has been a focus of a growing number of studies over the last two decades. However, most of the available studies are conducted in agricultural systems or grasslands, and hence very little information is available on rate and nature of soil organic matter (SOM) eroded from forested upland ecosystems. In the southern parts of the Sierra Nevada Mountains in California, we determined the rate of carbon (C) and nitrogen (N) eroded from two sets of catchments under different climatic conditions to determine how the amount and distribution of precipitation affects lateral distribution of topsoil and associated SOM. We quantified sediment and SOM exported annually (for water years 2005-2011) from four low-order, snow-dominated catchments, and four low-order catchments that receive a mix of rain, and snow and compared it to soil at three different landform positions from the source slopes to determine if there is selective transport of some soil OM components. We found that the amount of sediment exported varied from 0.4 to 177 kg N ha-1, while export of particulate C was between 0.025 and 4.2 kg C ha-1, compared to export of particulate N that was between 0.001 and 0.04 kg ha-1. Sediment yield and composition showed high interannual variation, with higher C and N concentrations in sediment collected in drier years. In our study catchments, erosion laterally mobilized OM-rich topsoil and litter material, some of which readily enters streams owing to the topography in these catchments that includes steep slopes adjacent to stream channels. Annual lateral sediment mass, C, and N fluxes were positively and strongly correlated with stream flows. Our results suggest that variability in climate, represented by stream discharge, is a primary factor controlling the magnitude of C and N eroded from upland temperature forest

  17. Two water worlds in temperate forests? Partitioning of water sources in two forested headwater catchments in Germany

    NASA Astrophysics Data System (ADS)

    Schmid, Bettina; Dubbert, Maren; Werner, Christiane; Hopp, Luisa

    2016-04-01

    Recent ecohydrological studies using stable isotopes have suggested that water used by plants is largely separated from water that is returned to streams and groundwater. These observations have led to the postulation of a "two water worlds hypothesis" with distinct reservoirs of water in the subsurface that are not well mixed. This has major implications for our understanding of the water cycle and its conceptualization. Most of the studies to date have been conducted in forested catchments located in regions with a pronounced seasonal distribution of precipitation. Here we present findings from a study of the ecological separation of water in two forested headwater catchments in Germany where precipitation is distributed rather evenly throughout the year. Over the course of 18 months we sampled plant water, soil water, groundwater and stream runoff monthly to analyze isotope ratios of 18O and 2H. Plant and soil water were cryogenically extracted, and isotope ratios in the water samples were analyzed using cavity ring-down spectroscopy and isotope-ratio mass spectrometry. The isotope ratios of the different water sources were used to test the hypothesis that separate water worlds also exist in climates that do not exhibit a seasonal distribution of precipitation. First findings indicate distinct differences in isotope ratios between tree species, suggesting complex processes at the biosphere-hydrosphere interface, but otherwise little evidence for the existence of separate water reservoirs.

  18. Fluvial sediment inputs to upland gravel bed rivers draining forested catchments: potential ecological impacts

    NASA Astrophysics Data System (ADS)

    Marks, S. D.; Rutt, G. P.

    As identified by the detailed long-term monitoring networks at Plynlimon, increased sediment supply to upland fluvial systems is often associated with forestry land-use and practice. Literature is reviewed, in the light of recent results from Plynlimon sediment studies, to enable identification of the potential ecological impacts of fluvial particulate inputs to upland gravel bed rivers draining forested catchments similar to the headwaters of the River Severn. Both sediment transport and deposition can have significant impacts upon aquatic vertebrates, invertebrates and plants.

  19. Large contribution of boreal upland forest soils to a catchment-scale CH4 balance in a wet year

    NASA Astrophysics Data System (ADS)

    Lohila, Annalea; Aalto, Tuula; Aurela, Mika; Hatakka, Juha; Tuovinen, Juha-Pekka; Kilkki, Juho; Penttilä, Timo; Vuorenmaa, Jussi; Hänninen, Pekka; Sutinen, Raimo; Viisanen, Yrjö; Laurila, Tuomas

    2016-03-01

    Upland forest soils affect the atmospheric methane (CH4) balance, not only through the soil sink but also due to episodic high emissions in wet conditions. We measured methane fluxes and found that during a wet fall the forest soil turned from a CH4 sink into a large source for several months, while the CH4 emissions from a nearby wetland did not increase. When upscaled to the whole catchment area the contribution of forests amounted to 60% of the annual CH4 emission from the wetlands, while in a normal year the forest soil consumes 10% of the wetland emission. The period of high upland soil emission was also captured by the nearby atmospheric concentration measurement station. Since the land cover within the catchment is representative of larger regions, our findings imply that upland forests in the boreal zone constitute an important part in the global CH4 cycle not previously accounted for.

  20. Storm event exports of dissolved organic nitrogen (DON) across multiple catchments in a glaciated forested watershed

    NASA Astrophysics Data System (ADS)

    Inamdar, Shreeram P.; Mitchell, Myron J.

    2007-06-01

    Storm event patterns of dissolved organic nitrogen (DON) were studied for multiple events across four catchments (1.6-696 ha) in a forested, glaciated watershed in western New York State. Highest concentrations of DON in the watershed were recorded for litter leachate followed by throughfall. Storm event concentrations of DON consistently peaked at or before peak discharge while dissolved organic carbon (DOC) concentrations peaked on the hydrograph recession limbs. Concentrations of DON in stream water were derived from throughfall and litter layer while the DOC expression was attributed to throughfall, litter, and the flushing of the mineral soil by a rising water table. Temporal patterns of ammonium (NH4+) concentrations during events consistently matched those of DON indicating similar sources and flow paths. A previously validated end-member mixing analysis (EMMA) for NO3- failed to predict the DON concentrations observed in streamflow. DON concentrations and DON as % of total dissolved nitrogen (TDN) differed considerably between baseflow (% DON: 6 to 19%) and storm events (% DON: 6 to 64%). DON concentrations and % DON of TDN increased with catchment size and amount of saturated/wetland areas. A wetland catchment that consistently yielded high storm-event DOC concentrations produced variable amounts of DON, indicating a decoupling of DOC and DON dynamics in the wetland. Our study suggests that storm events and watershed characteristics, especially the proportion of saturated and wetland areas, may have a greater influence on DON exports than atmospheric N deposition.

  1. Soil water erosion processes in mountain forest catchment - analysis by using terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Dąbek, Paweł; Żmuda, Romuald; Szczepański, Jakub; Ćmielewski, Bartłomiej; Patrzałek, Ciechosław

    2013-04-01

    The paper presents the results of the analysis of the water erosion processes of soil occurring in forestry mountain catchment area in the region of West Sudetes Mountain in Poland. The research was carried out within the experimental area of skid trails (operational trails), which were used to the end of 2010 in obtaining wood and its mechanical transport to the place of storage. As a consequence of forestry works that were carried out it was changing the natural structure of ground and its surface on the wooded slopes, which, combined with the favorable hydro-meteorological conditions contributed to the intensification of the water erosion processes of soil on surface of trails. For the implementation of the research project of the analysis of water erosion processes in the forestry catchment area innovative was used terrestrial laser scanning. Using terrestrial laser scanning has enabled the analysis of the dynamics of erosion processes both in time, as well as in spatial and quantitative terms. Scanning was performed at a resolution of 4 mm, resulting in 62 500 points per 1 square meter. After filtering the data were interpolated to other resolution of 1 cm, which can identify even the smallest linear and surface effects of erosion. While installed on the experimental area, along the skid trails, anti-erosion barriers in order to reduce transport eroded material and allow its accumulation. Allowed to precisely determine the location of areas of accumulation, the rate and amount of accumulated material. The result of the analyses that was carried out is identification areas of denudation of the eroded material, and also determine the intensity of the erosion processes and their quantitative analysis. The long-term researches on hydrological conditions and forest complexes functioning show that forest effectively stores water, limits linear and surface flow and delays water outflow from a catchment. Carried out a research project using the terrestrial laser

  2. Runoff, sediment and nutrient dynamics at plot and catchment scale following fire in wet eucalypt forests

    NASA Astrophysics Data System (ADS)

    Lane, Patrick; Sheridan, Gary; Noske, Phillip; Sherwin, Chris

    2010-05-01

    Two small mountain research catchments in SE Victoria, Australia, vegetated with wet eucalaypt forests were burnt in a wildfire in 2003. The experimental design produced a high resolution data set at plot and catchment scale on runoff, sediment and nutrient generation and fluxes, and the processes driving changes. The key findings were: • Annual discharge increased by around 70%, after the fire, and persisted for at least three years. At the plot scale there were orders of magnitude increases in overland flow generation under rainfall simulation • Flow duration curve analysis showed there was no apparent change in the runoff processes delivering water to the stream network, despite the rainfall simulation results • Suspended and coarse sediment fluxes increased by 8-9 times in the first year post-fire, but relaxed to pre-fire levels by the end of the second year • Phosphorus and nitrogen fluxes increased by perhaps 5-6 times, and showed the same recovery rate as sediment, with the majority of both P and N transported in fine particulate form • P enrichment ratios from plot to catchment were around 2, and the data suggests a relatively even split between organic and mineral P • Water quality recovery was a function of the ground cover recovery • There were no debris flows observed in these catchments despite rainfall and soil conditions that has triggered them in drier forest types nearby • Hillslope process experiments revealed the importance of soil water repellency and the spatial arrangement of saturated hydraulic conductivity in pollutant pathway length, and these data suggested near-stream areas to be the pollutant source areas • These experiments demonstrated that existing erosion process models do not work in these environments • The results from this study are germane to a wet eucalypt environment under "average" rainfall conditions and good vegetation recovery • A probabilistic approach to modelling is recommended to deal with extreme

  3. Do physicochemical sediment variables and their soft sediment macrofauna differ among microsize coastal lagoons with forested and urbanised catchments?

    NASA Astrophysics Data System (ADS)

    Mikac, K. M.; Maher, W. A.; Jones, A. R.

    2007-03-01

    Microsize intermittently open and closed coastal lagoons are a common feature of the coast of southern New South Wales, in southeast Australia. Many of these lagoons are undergoing development and urbanisation of their catchments, leading to concern about their ecological health. Consequently, it was hypothesised that lagoons with urbanised catchments should hav e finer, more contaminated sediments and fewer macrofaunal taxa (represented by opportunistic taxa) than lagoons that have undeveloped, forested catchments. To test these hypotheses, five lagoons with catchments dominated by either native forest or urban development were compared with respect to their sediment composition (i.e. sediment grain size, trace metal concentrations, organic carbon and nutrients) and soft sediment macrofaunal assemblages in the Batemans Bay region of southeast Australia. Using a nested design without temporal replication, replicate core samples were taken from sampling stations nested within lagoons that were nested within catchment type. Univariate and multivariate statistical analyses were used to test for significant differences and dissimilarities between catchment types and among lagoons. Of all the abiotic and biotic variables measured, only total nitrogen showed a difference between the two catchment types. Thus providing support to refute the explanatory model that urbanisation had negatively affected the sedimentary environment and macrofaunal composition of these microsize coastal lagoons. In contrast, differences among lagoons were usually significant with differences between the two forested lagoons, North Head and Acheron lagoon, being particularly large for assemblage composition and the abundance of some taxa; this variation may, potentially, obscure any effects of urbanisation. In addition, the information collected in this study provides a basic understanding of the physicochemical and biological aspects of microsize coastal lagoons in southeast Australia. Such

  4. Post-fire water quality in forest catchments: a review with implications for potable water supply

    NASA Astrophysics Data System (ADS)

    Smith, Hugh; Sheridan, Gary; Lane, Patrick; Nyman, Petter; Haydon, Shane

    2010-05-01

    In many locations fire-prone forest catchments are utilised for the supply of potable water to small communities up to large cities. For example, in south-eastern Australia, wildfires have burned part or all of forest catchments supplying drinking water to Sydney (2001 wildfire), Canberra (2003), Adelaide (2007), Melbourne (2009), as well as various regional towns. Generally, undisturbed forest catchments are a source of high quality water. However, increases in erosion and sediment flux, runoff generation, and changes to the supply of key constituents after wildfire may result in contamination of water supplies. In this review, we present key physical and chemical constituents from a drinking water perspective that may be generated in burned forest catchments and examine post-fire changes to concentrations of these constituents in streams and reservoirs. The World Health Organisation (WHO) drinking water guideline values were used to assess reported post-fire constituent concentrations. Constituents examined include suspended sediment, ash, nutrients, trace metals, anions (Cl-, SO42-), cyanides, and polycyclic aromatic hydrocarbons (PAHs). Constituent concentrations in streams and reservoirs vary substantially following wildfire. In streams, maximum reported total suspended solid concentrations (SSC) in the first year after fire ranged from 11 to 143,000 mg L-1. SSC is often measured in studies of post-fire stream water quality, whereas turbidity is used in drinking water guidelines and more commonly monitored in water supply reservoirs. For burned catchment reservoirs in south-eastern Australia, peak turbidities increased over pre-fire conditions, as did the frequency of exceedance of the turbidity guideline. NO3-, NO2-, and NH4+ may increase after wildfire but maximum recorded concentrations have not exceeded WHO guideline values. Large post-fire increases in total N and total P concentrations in streams and reservoirs have been observed, although there are no

  5. Catchment conceptualisation for examining applicability of chloride mass balance method in an area of historical forest clearance

    NASA Astrophysics Data System (ADS)

    Guan, H.; Love, A.; Simmons, C. T.; Ding, Z.; Hutson, J.

    2009-11-01

    Among various approaches for estimating groundwater recharge, chloride mass balance (CMB) method is one of the most frequently used, in particular, for arid and semiarid regions. Widespread native vegetation clearance, common history in many areas globally, has changed land surface boundary condition, posing a question whether the current system has reached new chloride equilibrium for CMB application. To examine CMB applicability for catchments, conceptual catchment types of various chloride equilibrium conditions are defined. The conceptualization, combined with some local climate conditions, is demonstrated to be useful in examining whether a catchment has reached new chloride equilibrium. The six conceptual catchment types are tested with eleven selected catchments in the Mount Lofty Ranges (MLR), a coastal hilly area in South Australia having experienced historical widespread forest clearance. The results show that six of the eleven catchments match type VI chloride balance condition (chloride non-equilibrium with a gaining stream), with the ratio of stream chloride output over atmospheric chloride input (catchment chloride O/I) ranging from 2 to 4. Two catchments match type V chloride balance condition (chloride non-equilibrium with a losing stream), with catchment chloride O/I values about 0.5. For these catchments, the CMB method is not appropriate to apply. The results also suggest that neither a below-one chloride O/I value nor a low seasonal fluctuation of streamflow chloride concentration (a factor below 4) guarantees a chloride equilibrium condition in the study area. But a large chloride O/I value (above one) and a large fluctuation of streamflow chloride concentration (a factor of 10 and above) generally indicates either a chloride disequilibrium, or cross-catchment water transfer, or both, for which CMB is not applicable. Based on the regression between chloride O/I values and annual precipitation for type VI catchments, a catchment with annual

  6. Catchment conceptualisation for examining applicability of chloride mass balance method in an area with historical forest clearance

    NASA Astrophysics Data System (ADS)

    Guan, H.; Love, A. J.; Simmons, C. T.; Hutson, J.; Ding, Z.

    2010-07-01

    Of the various approaches for estimating groundwater recharge, the chloride mass balance (CMB) method is one of the most frequently used, especially for arid and semiarid regions. Widespread native vegetation clearance, common in many areas globally, has changed the land surface boundary condition, posing the question as to whether the current system has reached new chloride equilibrium, required for a CMB application. Although a one-dimensional CMB can be applied at a point where the water and chloride fluxes are locally in steady state, the CMB method is usually applied at a catchment scale owing to significant lateral flows in mountains. The applicability of the CMB method to several conceptual catchment types of various chloride equilibrium conditions is examined. The conceptualisation, combined with some local climate conditions, is shown to be useful in assessing whether or not a catchment has reached new chloride equilibrium. The six conceptual catchment types are tested with eleven selected catchments in the Mount Lofty Ranges (MLR), a coastal hilly area in South Australia having experienced widespread historical forest clearance. The results show that six of the eleven catchments match a type VI chloride balance condition (chloride non-equilibrium with a gaining stream), with the ratios of stream chloride output (O) over atmospheric chloride input (I), or catchment chloride O/I ratios, ranging from 2 to 4. Two catchments match a type V chloride balance condition (chloride non-equilibrium with a losing stream), with catchment chloride O/I ratios about 0.5. For these type V and type VI catchments, the CMB method is not applicable. The results also suggest that neither a chloride O/I ratio less than one nor a low seasonal fluctuation of streamflow chloride concentration (a factor below 4) guarantees a chloride equilibrium condition in the study area. A large chloride O/I value (above one) and a large fluctuation of streamflow chloride concentration (a factor

  7. Estimating the collapse of aggregated fine soil structure in a mountainous forested catchment.

    PubMed

    Mouri, Goro; Shinoda, Seirou; Golosov, Valentin; Chalov, Sergey; Shiiba, Michiharu; Hori, Tomoharu; Oki, Taikan

    2014-06-01

    This paper describes the relationship of forest soil dryness and antecedent rainfall with suspended sediment (SS) yield due to extreme rainfall events and how this relationship affects the survival of forest plants. Several phenomena contribute to this relationship: increasing evaporation (amount of water vapour discharged from soil) due to increasing air temperature, decreasing moisture content in the soil, the collapse of aggregates of fine soil particles, and the resulting effects on forest plants. To clarify the relationships among climate variation, the collapse of soil particle aggregates, and rainfall-runoff processes, a numerical model was developed to reproduce such aggregate collapse in detail. The validity of the numerical model was confirmed by its application to the granitic mountainous catchment of the Nagara River basin in Japan and by comparison with observational data. The simulation suggests that important problems, such as the collapse of forest plants in response to decreases in soil moisture content and antecedent rainfall, will arise if air temperature continues to increase. PMID:24055411

  8. Trends of precipitation and streamwater chemistry at a subtropical forested catchment, northeastern Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, Chung-Te; Huang, -Chuan, Jr.; Lin, Teng-Chiu

    2016-04-01

    The assessment of long-term input-output budgets has been widely used to examine the impacts of acidic deposition on temperature forest ecosystems, but rarely in subtropical forest ecosystem. In this study, we used weekly bulk precipitation and streamwater chemistry data collected between 1994 and 2013 in a small catchment in northeastern Taiwan. The long-term volume-weighted mean pH of precipitation and streamwater were 4.64 and 6.79 respectively which indicated that the stream was capable of neutralizing common acidic deposition. Precipitation revealed a significant decline trend in Ca2+, NH4+, and NO3‑ concentration and fluxes in the summer possibly due to decreases of local emissions in Taiwan. But the persistent high levels of NO3‑ and SO42‑ during winter period over the past 20 years could a potential threat to forest ecosystems in the region. Although the concentrations and fluxes of all elements in streamwater showed high intern-annual variation, there were no significant trends. The long-term nutrient budget indicates net loss for Na+, Mg2+, Ca2+, NO3‑ and SO42‑, net retention for NH4+ and Cl‑ and near balance for K+. The significant trend of net export of NO3‑ during the study period calls for further investigation to clarify if nitrogen saturation is occurring due to the high acid deposition or if other factors such as typhoon disturbance are driving its dynamics. From the comparisons between seasonal and annual budgets, it is clear that hydrological flux instead of biological activities dominated the biogeochemical processes and this is very different from the biotic control of biogeochemistry in temperate forest ecosystem (e.g. Hubbard Brook Experimental Forest). Our results also have important implications on the effects of climate change on biogeochemical cycles. Keywords: acid deposition, nutrient budget, biogeochemistry, forest ecosystem, subtropical mountainous island.

  9. Nitrogen and Carbon Cycling in Deforested and Pristine Upland (2400m) Forest Catchments in the Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Townsend-Small, A.; Haberer, J.; McClain, M.; Ramos, O.; Gardner, W.; McCarthy, M.; Brandes, J.

    2001-12-01

    Nitrogen and carbon cycling were examined within two upland (2400m) forest catchments in the Peruvian Andes. One catchment was partially deforested within the last 3 years, while the other has remained untouched. Tracer amended samples were analyzed to determine the pathways and rates of nitrogen cycling in streams draining each catchment. Both streams exhibited very low inorganic nitrogen levels, on the order of 1 to 2 uM. A large percentage (>1/3) of the total fixed nitrogen flux from these systems was in the form of particulates. Preliminary results suggest a very high rate of nitrogen cycling in these systems. Isotopic measurements of plant samples from both catchments also suggest that these forests are highly efficient in trapping and using atmospheric nitrogen sources. The partially deforested catchment had significantly more species using C4 and CAM carbon fixation pathways. Leaf litter from both streams and leaves from trees in the area were also analyzed for carbon and nitrogen isotopes to compare and contrast nitrogen and carbon cycling between the two sites. This and other data to be presented suggest that deforestation has subtle but significant effects upon the ability of tropical upland forests to retain and use nutrients.

  10. Redox properties of dissolved organic matter along redox gradients in two peatland-dominated forested catchments

    NASA Astrophysics Data System (ADS)

    Schmitt, Markus; Sander, Michael; Blodau, Christian; Peiffer, Stefan; Knorr, Klaus-Holger

    2015-04-01

    Dissolved organic matter (DOM) contributes significantly to the carbon cycle and influence the mobility of metals and contaminants. Water logged, riparian wetlands have been identified as an important source of DOM in catchments. As DOM export from wetlands often involves transitions in redox conditions, for a more mechanistic understanding of sources, mobilization processes and fate of DOM under different redox conditions additional analytical approaches are needed. In this study we combined established methods for DOM characterization, such as fluorescence spectroscopy and δ13CDOC, with mediated electrochemical reduction and oxidation of DOM for the determination the electron accepting and donating capacity (EAC/EDC). With this approach, we intended to test if the redox state of DOM can be used to identify and characterize its sources in catchments. To this end, we collected samples in two catchments - one dominated by fens and forest, the other by an ombrotrophic bog - from different hydrological compartments and from different source materials. EAC strongly decreased from oxic groundwater (6.4 ± 2.1 mmole- gC -1) to anoxic peat pore water (0.6 ± 0.5 mmole- gC -1). Contrarily, for EDC, there was no clear pattern to separate water compartments with different redox states. EDC seemed thus to depend mainly on the DOM source materials. Results of fluorescence spectroscopy and δ13CDOCconfirmed that changes in EDC were presumably due to changes in DOC quality rather than redox state. Moreover, comparing peat pore water and DOM in an adjacent erosion rill, EDC increased from 0.7 mmole- gC -1 in the anoxic pore water to 1.7 ± 0.2 mmole- gC -1 along the flow path in the oxic stream. This further suggested a different mobility of different DOM fractions, with higher EDC in more mobile DOM. This study indicates that combining electrochemical and spectroscopic methods for characterization of DOM quality and redox state can improve our understanding of source and fate

  11. The seasonal variation of streamwater chemistry in three forested Mediterranean catchments

    NASA Astrophysics Data System (ADS)

    Piñol, Josep; Ávila, Anna; Rodà, Ferran

    1992-12-01

    Streamwater chemistry is described for three streams draining undisturbed, evergreen broad-leaved forested catchments on phyllites in NE Spain: two streams with no or negligible flow in summer are located in the Prades massif, and one perennial stream is in the wetter Montseny mountains. Weekly data for a study period of 2-4 years are provided to (1) describe the seasonal variations in streamwater chemistry, (2) analyse the relationship between stream discharge and solute concentrations using a two-component mixing model and (3) search for patterns of temporal variation in stream solute concentrations after discounting the effects of discharge. At Prades, concentrations of all analysed ions, except NO -3, showed marked seasonal variations in stream water, whereas at Montseny only ions related to mineral weathering (HCO -3, Na +, Ca 2+ and Mg 2+) showed strong seasonality. Ion concentrations were more closely dependent on instantaneous discharge at Montseny than at Prades. The residuals of the relationship between solute concentrations and discharge retained a strong seasonality at Prades, but not at Montseny. These differences are related to the major hydrochemical processes that determine the streamwater chemistry at each site. The same processes are probably operative in the three catchments, but are of varying relative importance. At Montseny, the mixing of waters of different chemical composition seems to be the major process controlling streamwater chemistry, although the soilwater end-member composition predicted by the mixing model applied did not match the measured soilwater chemistry. In the drier Prades catchments, the two major hydrochemical processes determining the seasonal variation of streamwater chemistry are (1) the restart of flow after the summer drought, which flushes out the solutes accumulated during the dry period, and (2) the seasonal changes in groundwater chemistry that result from the interplay of water residence time, temperature and CO

  12. Incorporating preferential flow into a 3D model of a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Glaser, Barbara; Jackisch, Conrad; Hopp, Luisa; Pfister, Laurent; Klaus, Julian

    2016-04-01

    Preferential flow plays an important role for water flow and solute transport. The inclusion of preferential flow, for example with dual porosity or dual permeability approaches, is a common feature in transport simulations at the plot scale. But at hillslope and catchment scales, incorporation of macropore and fracture flow into distributed hydrologic 3D models is rare, often due to limited data availability for model parameterisation. In this study, we incorporated preferential flow into an existing 3D integrated surface subsurface hydrologic model (HydroGeoSphere) of a headwater region (6 ha) of the forested Weierbach catchment in western Luxembourg. Our model philosophy was a strong link between measured data and the model setup. The model setup we used previously had been parameterised and validated based on various field data. But existing macropores and fractures had not been considered in this initial model setup. The multi-criteria validation revealed a good model performance but also suggested potential for further improvement by incorporating preferential flow as additional process. In order to pursue the data driven model philosophy for the implementation of preferential flow, we analysed the results of plot scale bromide sprinkling and infiltration experiments carried out in the vicinity of the Weierbach catchment. Three 1 sqm plots were sprinkled for one hour and excavated one day later for bromide depth profile sampling. We simulated these sprinkling experiments at the soil column scale, using the parameterisation of the base headwater model extended by a second permeability domain. Representing the bromide depth profiles was successful without changing this initial parameterisation. Moreover, to explain the variability between the three bromide depth profiles it was sufficient to adapt the dual permeability properties, indicating the spatial heterogeneity of preferential flow. Subsequently, we incorporated the dual permeability simulation in the

  13. Examining responses of suspended sediment transports after intense thinning in a forested headwater catchment using nested monitoring

    NASA Astrophysics Data System (ADS)

    Nam, S.; Gomi, T.; Onda, Y.; Hiraoka, M.; Dung, B. X.; Kato, H.

    2014-12-01

    We examined responses of suspended sediment (SS) transports after 50% intense thinning in a 17 ha forested headwater catchment using nested 4 to 10 ha gauging stations. Strip thinning of 13- to 45-yr Japanese cedar (Cryptomeriajaponica) and cypress (Chamaecyparisobtusa) was conducted by cable dragging to skid trails in the entire watershed including nested sub-catchments. The skid trails density varied from 0 to 134 m/ha, followed by 4 m/ha. Peak SS yields monitored by turbidity sensor at the catchment outlet was 10-folds greater after the first year of thinning by comparing the pre-thinning conditions, while these values became 2-folds in the third year after thinning. This changes of peak SS concentrations suggested that recovery of vegetation cover on disturbed soil reduced peak concentrations of SS. We also confirmed changes in SS yields and recovery using paired-catchment analysis. Integrated SS yields including periods during thinning operation from August to October, 2011 varied from 0.03 to 0.06 kg. Integrated SS yields in the catchment outlet (0.05 kg) were corresponded to 5.0 kg/ha in SS yields. Organic matter content of integrated SS samples in one sub-catchment was low (0%), while the other catchments contained 0.08 and 0.13% of organic matter. 210Pbex activity in the sub-catchment (181 Bq/kg) with low organic matter content was the highest among the other nested catchments from 36 to 59 Bq/kg. Because mean 210Pbex activity from < 10 cm soil surface depth along hillslopes transects was 124 ± 83 Bq/kg, soil surface erosion from < 10 cm depth on the soil surface can be contributed to fine sediment supplies for the sub-catchments with high 210Pbex activity. In contrast, 210Pbex activity on the skid trails was low, because soil disturbance became deep with > 10 cm. Therefore, fine sediment with low 210Pbex activity on the skid trails can be transported to the catchment outlet. These characteristics were also confirmed by 137Cs activity with various

  14. Confidence interval in estimating solute loads from a small forested catchment

    NASA Astrophysics Data System (ADS)

    Tada, A.; Tanakamaru, H.

    2007-12-01

    The evaluation of uncertainty in estimating mass flux (load) from catchments plays the important role in the evaluation of chemical weathering, TMDLs implementation, and so on. Loads from catchments are estimated with many methods such as weighted average, rating curve, regression model, ratio estimator, and composite method, considering the appropriate sampling strategy. Total solute loads for 10 months from a small forested catchment were calculated based on the high-temporal resolution data and used in evaluating the validity of 95% confidence intervals (CIs) of estimated loads. The effect of employing random and flow-stratified sampling methods on 95% CIs was also evaluated. Water quality data of the small forested catchment (12.8 ha) in Japan was collected every 15 minutes during 10 months in 2004 to acquire the 'true values' of solute loads. Those data were measured by the monitoring equipment using FIP (flow injection potentiometry) method with ion-selective electrodes. Measured indices were sodium, potassium, and chloride ion in the stream water. Water quantity (discharge rate) data were measured continuously by the V-notch weir at the catchment outlet. The Beale ratio estimator was employed as the estimation method of solute loads because it was known as unbiased estimator. The bootstrap method was also used for calculating the 95% confidence intervals of solute loads with 2,000 bootstrap replications. Both flow-stratified and random sampling was adopted as sampling strategy which extracted sample data sets from the entire observations. Discharge rate seemed to be a dominant factor of solute concentration because the catchment was almost undisturbed. The validity of 95% CIs were evaluated using the number of inclusion of 'true value' inside CIs out of 1,000 estimations derived from independently and iteratively extracted sample data sets. The number of samples in each data set was set to 5,500, 950, 470, 230, 40, and 20, equivalent to hourly, 6-hourly, 12

  15. Understanding the spatial and temporal variability of water sources in a humid forested catchment

    NASA Astrophysics Data System (ADS)

    Pianezzola, Luisa; Zuecco, Giulia; Pozzoni, Santiago; Penna, Daniele; Borga, Marco

    2016-04-01

    The detailed understanding of the hydrological response of humid forested catchments is hampered by the marked spatial and temporal variability of water sources. In this work, we use environmental tracers (major ions, electrical conductivity and stable isotopes of water) coupled to hydrometric data to infer the main contributors to streamflow and their spatio-temporal variability during rainfall events in a small forested catchment in the Italian pre-Alps. Specifically, we aim to i) identify the main end-members for stream runoff; ii) evaluate their spatial and temporal variability, and iii) quantify the component fractions in stream runoff. Data collection took place in the 1.96-ha Ressi catchment between August 2012 and November 2015. Streamflow, precipitation, air temperature, shallow groundwater levels at six spatially-distributed locations and soil moisture at four locations along a riparian-hillslope transect were continuously measured. Monthly water samples were collected from precipitation, stream, shallow groundwater, soil water at 20 cm depth in two suction cups in the riparian and hillslope zone. Electrical conductivity was measured in the field by a portable meter, isotopic composition was determined by laser absorption spectroscopy and ionic concentrations by ion-chromatography. Samples for major ions were collected from September 2015 also during three rainfall-runoff events at high temporal frequency. End-member mixing analysis and tracer-based two- and three-component hydrograph separation techniques were employed, providing different scenarios of streamflow component fractions according to the use of isotopic data and of the three cations with largest concentrations (calcium, magnesium and sodium), and groundwater in different wells. Preliminary results reveal that precipitation, soil water in the riparian zone, and shallow groundwater are the main contributors to stream runoff. Riparian groundwater in the lower part of the catchment sustains

  16. Identifying the role of environmental drivers in organic carbon export from a forested peat catchment.

    PubMed

    Ryder, Elizabeth; de Eyto, Elvira; Dillane, Mary; Poole, Russell; Jennings, Eleanor

    2014-08-15

    Carbon export in streams draining peat catchments represents a potential loss of carbon from long-term stores to downstream aquatic systems and ultimately, through mineralisation, to the atmosphere. There is now a large body of evidence that dissolved organic carbon (DOC) export has increased significantly in recent decades at many sites, although there is still debate about the drivers of this increase. In this study, DOC export and particulate organic carbon (POC) export were quantified from a forested peatland catchment in the west of Ireland over two years at a fine temporal resolution. The principle drivers of change in stream DOC and POC concentrations were investigated using a general additive modelling (GAM) approach. The study period included drought conditions in the early summer of 2010 and clearfelling of some commercial forestry in early 2011. The results indicated that annual loads of 9.5 t DOC km(2) year(-1) and 6.2 t POC km(2) year(-1) were exported from the catchment in 2010. This combined annual load of 15.7 t C km(2) year(-1) would represent between 0.01% and 0.02% of typical estimates for peat soil carbon storage in the region. Soil temperature, river discharge and drought explained 59.7% the deviance in DOC concentrations, while soil temperature, river discharge, and rainfall were the significant drivers of variation in POC concentrations, explaining 58.3% of deviance. Although clearfelling was not a significant factor in either model, large spikes in POC export occurred in 2011 after the first forestry clearance. The results illustrate the complexity of the interactions between climate and land management in driving stream water carbon export. They also highlight the sensitivity of peatland carbon stores to changes in temperature and precipitation, which are projected to be more extreme and variable under future climate scenarios. PMID:24840277

  17. Stream and bed temperature response to partial-retention forest harvesting in a coastal headwater catchment

    NASA Astrophysics Data System (ADS)

    Moore, R. D.; Guenther, S.; Gomi, T.

    2012-12-01

    This study quantified the effects of partial-retention forest harvesting on stream and bed temperatures in a headwater catchment in coastal British Columbia, Canada. Stream temperature was recorded between 2002 and 2005 at four sites, three located within the harvested area and one upstream. Logging occurred in autumn 2004. Shallow groundwater temperatures, along with bed temperature profiles at depths of 1 to 30 cm, were recorded at 10-minute intervals in two hydrologically distinct reaches beginning in 2003 or 2004, depending on the site. The lower reach had smaller discharge contributions via lateral inflow from the hillslopes and fewer areas with upwelling and/or neutral flow across the stream bed compared to the middle reach. Based on a paired-catchment analysis, the logging treatment resulted in higher daily maximum stream and bed temperatures but smaller changes in daily minima. Changes in daily maximum stream temperature, averaged over July and August of the post-harvest year, ranged from 1.6 to 3 oC at different locations within the cut block. Post-harvest changes in bed temperature in the lower reach were lower than the changes in stream temperature, greater at sites with downwelling flow, and decreased with depth at both upwelling and downwelling sites, dropping to about 1 oC at a depth of 30 cm. In the middle reach, changes in daily maximum bed temperature, averaged over July and August, were generally about 1 oC and did not vary significantly with depth. The pre-harvest regression models for shallow groundwater were not suitable for applying the paired-catchment analysis to estimate the effects of harvesting.

  18. Analysis on DOC transformation in a forested catchment using stable carbon isotope values

    NASA Astrophysics Data System (ADS)

    Ohte, N.; Takahashi, Y.; Itoh, M.; Katsuyama, M.; Fujimoto, M.; Matsuo, N.; Tani, M.

    2009-12-01

    In order to elucidate the production, consumption and transformation mechanisms of dissolved organic carbon (DOC) in temperate forested catchment , time and spatial variations in several parameters which characterize the DOC quality were surveyed in various hydrological processes in a headwater catchment in central Japan. Rain, through fall, soil waters in various depths, groundwater and streamwater were sampled since June 2006 to November 2008. Concentration, δ13C, fluorescence spectrum and UV absorbance of DOC were measured. We measured the δ13C-DOC values using an IRMS with a CO2 purifying system connected to a TOC analyzer. Combined discussions on the profiles of concentration, δ13C and fluorescence characteristics provided following findings: 1) Microbial decomposition of DOC was commonly predominant for consumption in relatively shallower soil horizons (0 to 30 cm in depth) regardless of the soil moisture condition among the soil profiles at the different parts in hillslope, while adsorption was significant in the relatively dry soil profile. 2) During this process, persistent portions remained preferentially in the soil solution. 3) In the groundwater body, two different processes caused; protein-like dissolved organic carbon was added in the relatively oxygen rich part and the δ13C value decreased with the anoxic DOC decomposition in the oxygen poor part, suggesting the methanogenic activity related DOC production (Figure 1). Stream DOC characteristics were determined by relative contributions of subsurface water and groundwater. Then, it received fresh DOC with high fulvic fluorescence peak from bank side or riparian zones again. These indicated that the stream DOC characteristics were influenced not only by in stream and streamside organic supply, but also terrestrial DOC formation through the groundwater discharge. Figure 1. Relationship between UV/DOC and δ13C-DOC of soil water at three different soil profiles. G1, G34 and G27 were located in the

  19. Unravelling past flash flood activity in a forested mountain catchment of the Spanish Central System

    NASA Astrophysics Data System (ADS)

    Ballesteros-Cánovas, Juan A.; Rodríguez-Morata, Clara; Garófano-Gómez, Virginia; Rubiales, Juan M.; Sánchez-Salguero, Raúl; Stoffel, Markus

    2015-10-01

    Flash floods represent one of the most common natural hazards in mountain catchments, and are frequent in Mediterranean environments. As a result of the widespread lack of reliable data on past events, the understanding of their spatio-temporal occurrence and their climatic triggers remains rather limited. Here, we present a dendrogeomorphic reconstruction of past flash flood activity in the Arroyo de los Puentes stream (Sierra de Guadarrama, Spanish Central System). We analyze a total of 287 increment cores from 178 disturbed Scots pine trees (Pinus sylvestris L.) which yielded indications on 212 growth disturbances related to past flash flood impact. In combination with local archives, meteorological data, annual forest management records and highly-resolved terrestrial data (i.e., LiDAR data and aerial imagery), the dendrogeomorphic time series allowed dating 25 flash floods over the last three centuries, with a major event leaving an intense geomorphic footprint throughout the catchment in 1936. The analysis of meteorological records suggests that the rainfall thresholds of flash floods vary with the seasonality of events. Dated flash floods in the 20th century were primarily related with synoptic troughs owing to the arrival of air masses from north and west on the Iberian Peninsula during negative indices of the North Atlantic Oscillation. The results of this study contribute considerably to a better understanding of hazards related with hydrogeomorphic processes in central Spain in general and in the Sierra de Guadarrama National Park in particular.

  20. Biogeochemistry of organic and inorganic arsenic species in a forested catchment in Germany.

    PubMed

    Huang, Jen-How; Matzner, Egbert

    2007-03-01

    Little is known about the fate and behavior of diffuse inputs of arsenic (As) species in forested catchments which often are the sources of drinking water. The objective of this study was to investigate the mobility and transformation of different As species in forest ecosystems to assess the environmental risk related to the diffuse pollution of As. We determined concentrations and fluxes in precipitation, litterfall, soil solutions (Oa horizon and 20- and 90-cm depth), and runoff of organic and inorganic As species and Astotal in a forest ecosystem in NE-Bavaria, Germany. The concentrations of Astotal were mostly <1 microg As L(-1) in aqueous samples and were highest in forestfloor percolates (7.6 microg As L(-1)). In litterfall, the concentrations of As species never exceeded 0.1 microg As g(-1). Arsenate and arsenite were the prevalent As species in all samples. Organic As species, comprising monomethylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, arsenobetaine, and three unidentified organic As species, were mostly found in throughfall reaching up to 45% of Astotal. The total deposition of Astotal (calculated as throughfall + litterfall) was 5.6 g As ha(-1) yr(-1) with 16% contribution of litterfall. The annual Astotal fluxes were 30 g As ha(-1) yr(-1) for forest floor percolates, 8.0 g As ha(-1) yr(-1) at 20-cm soil depth, and 1.4 g As ha(-1) yr(-1) at 90-cm soil depth. The annual runoff of Astotal from the catchment amounted to 3.8 g As ha(-1) yr(-1). The annual fluxes of total organic As species was highest in total deposition (1.1 g As ha(-1) yr(-1)) and decreased largely with depth in the soil profile. The annual runoff of total organic As species was only 0.08 g As ha(-1) yr(-1). Significant correlations in soil solutions and runoff were found between Astotal and dissolved organic C and Fe. Correlations between Astotal concentrations in runoff and water fluxes were seasonally dependent and with a steeper slope in the growing season than in

  1. Soil processes drive seasonal variation in retention of 15N tracers in a deciduous forest catchment.

    PubMed

    Goodale, Christine L; Fredriksen, Guinevere; Weiss, Marissa S; McCalley, K; Sparks, Jed P; Thomas, Steven A

    2015-10-01

    Seasonal patterns of stream nitrate concentration have long been interpreted as demonstrating the central role of plant uptake in regulating stream nitrogen loss from forested catchments. Soil processes are rarely considered as important drivers of these patterns. We examined seasonal variation in N retention in a deciduous forest using three whole-ecosystem 15N tracer additions: in late April (post-snowmelt, pre-leaf-out), late July (mid-growing- season), and late October (end of leaf-fall). We expected that plant 15N uptake would peak in late spring and midsummer, that immobilization in surface litter and soil would peak the following autumn leaf-fall, and that leaching losses would vary inversely with 15N retention. Similar to most other 15N tracer studies, we found that litter and soils dominated ecosystem retention of added 15N. However, 15N recovery in detrital pools varied tremendously by season, with > 90% retention in spring and autumn and sharply reduced 15N retention in late summer. During spring, over half of the 15N retained in soil occurred within one day in the heavy (mineral-associated) soil fraction. During summer, a large decrease in 15N retention one week after addition coincided with increased losses of 15NO3- to soil leachate and seasonal increases in soil and stream NO3- concentrations, although leaching accounted for only a small fraction of the lost 15N (< 0.2%). Uptake of 15N into roots did not vary by season and accounted for < 4% of each tracer addition. Denitrification or other processes that lead to N gas loss may have consumed the rest. These measurements of 15N movement provide strong evidence for the dominant role of soil processes in regulating seasonal N retention and losses in this catchment and perhaps others with similar soils. PMID:26649387

  2. Identifying weathering processes by Si isotopes in two small catchments in the Black Forest (Germany)

    NASA Astrophysics Data System (ADS)

    Steinhoefel, G.; Breuer, J.; von Blanckenburg, F.; Horn, I.; Kaczorek, D.; Sommer, M.

    2013-12-01

    Stable Si isotopes are potentially an ideal proxy to investigate weathering as the release or precipitation of Si during abiotic or biotic processes causes significant shifts in the isotope signature depending on the weathering intensity. In this study, we determine the Si isotope signature of spring and stream waters and of the principle Si pools of typical soil profiles within two small catchments located on sandstone and paragneiss, respectively, in the cold, perhumid Black Forest (Germany). The Si isotope data were obtained on a Neptune MC-ICP-MS in solution for the water samples and in situ by coupling a UV femtosecond laser ablation system for solid samples, respectively. Bulk soils show a largely homogeneous Si isotope signature for different horizons and locations, which is close to those of bulk bedrocks with δ30Si value around -0.3‰. Soil clay formation is associated with limited Si mobility, which preserves initial Si isotope signatures of parental minerals. Biogenic mineral, i.e. phytoliths, exhibit negative Si isotope signature of about -0.4‰. An exception are the topsoil layers in the paragneiss catchment where the organic-rich environment promotes high Si mobility leading to a significant depletion of heavy Si isotopes. Springs and streams, sampled in spring and late summer, vary between -0.7 to 1.1‰ in δ30Si showing spatial and temporal variations dependent on the water pathways. Groundwater originated from sandstone and overlying periglacial debris layers reveals constant δ30Si values of 0.3 to 0.5‰, which is attributed to kaolinite formation. In contrast, water passing the soil zone shows very variable signatures. Low δ30Si values down to -0.7‰ most likely reflects dissolution processes of clay minerals and phytoliths during spring. In late summer, positive δ30Si values expose the impact of preferential uptake of light Si isotopes by plants. In the paragneiss catchment, this effect is likely increased by co-precipitation of

  3. Summer storms trigger soil N2O efflux episodes in forested catchments

    NASA Astrophysics Data System (ADS)

    Enanga, E. M.; Creed, I. F.; Casson, N. J.; Beall, F. D.

    2016-01-01

    Climate change and climate-driven feedbacks on catchment hydrology and biogeochemistry have the potential to alter the aquatic versus atmospheric fate of nitrogen (N) in forests. This study investigated the hypothesis that during the forest growth season, topography redistributes water and water-soluble precursors (i.e., dissolved organic carbon and nitrate) for the formation of gaseous N species. Soil nitrous oxide (N2O) and nitrogen (N2) efflux and soil physical and chemical properties were measured in a temperate forest in Central Ontario, Canada from 2005 to 2010. Hotspots and hot moments of soil N2O and N2 efflux were observed in topographic positions that accumulate precipitation, which likely triggered the formation of redox conditions and in turn intercepted the conversion of nitrate N flowing to the stream by transforming it to N2O and N2. There was a strong relationship between precipitation and N2O efflux (y = 0.44x1.22, r2 = 0.618, p < 0.001 in the inner wetland; y = 1.30x1.16 r2 = 0.72, p < 0.001 in the outer wetland) and significantly different N2:N2O ratios in different areas of the wetland (19.6 in the inner wetland and 10.1 in the outer wetland). Soil N2O + N2 efflux in response to precipitation events accounted for 16.1% of the annual N input. A consequence of the higher frequency of extreme precipitation events predicted under climate change scenarios is the shift from an aquatic to atmospheric fate for N, resulting in a significant forest N efflux. This in turn creates feedbacks for even warmer conditions due to increased effluxes of potent greenhouse gases.

  4. Catchment streamflow response to climate change conditioned by historic alterations of land-use: forest harvest, succession, and stand conversion.

    NASA Astrophysics Data System (ADS)

    Young, D. A., II; Zegre, N.; Edwards, P.; Strager, M.

    2014-12-01

    Headwater streams provide drinking water for millions of people and serve a significant nexus, contributing to the physical, chemical, and biological integrity of navigable waters. Long-term research sites, such as the Fernow Experimental Forest serve as the regions bellwether for ecological change. Nevertheless, few studies have quantified the long term impacts of forest treatment and climate change on streamflow for the catchments of the Fernow. This study serves this roll by accessing the change in water and energy balance of four catchments (WS-1, WS-4, WS-6, WS-7) subject to forest harvest, natural and suppressed regrowth, and stand conversion. We apply the Budyko framework to quantify the relative contributions of climate and land cover changes on annual streamflow between two time periods and over a five year interval spanning 1951-2011. Based on this analysis land-use, forest succession, and climate change-variability are differentially impacting streamflow. In the two-period analysis climate change is responsible for on average 3 % change in mean annual runoff (MAR). Forest harvest and/or succession caused changes in MAR of -0.8 % to -30.0 %. The Budyko decomposition method applied over five year intervals captured the influence of forest treatment on streamflow well. However, the reference (WS-4) is changing in ways that climate alone cannot describe. Overall, it is important to consider how climate, land-use disturbance, and forest succession corroborate by distinguishing their respective impacts.

  5. Impact of forest disturbance on the runoff response in headwater catchments. Case study: Sumava mountains, Czech republic

    NASA Astrophysics Data System (ADS)

    Langhammer, Jakub; Hais, Martin; Bartunkova, Kristyna; Su, Ye

    2013-04-01

    The forest disturbance and stream modifications are important phenomenon affecting the natural dynamics of erosion and sedimentation processes on montane and submontane streams. The changes in land use, land cover structure, forest cover and stream modifications, occurring in the cultural landscape have significant effect on the dynamics of fluvial processes, especially in relation to the extreme runoff events. The contribution discusses the relations between forest disturbance and fluvial dynamics, stemming from the research in Sumava Mountains, located at the border between Czech Republic and Germany, Central Europe. The study area is located in headwater region, affected by different types of forest disturbance in past three decades - bark beetle outbreak, repeated windstorms and clear-cut forest management. The streams in experimental catchments here displayed extensive dynamics of erosion and sedimentation after the extreme floods in 2002 and 2009 and were affected by artificial modifications. The analysis is based on the combination of different research techniques, including remote sensed data processing, network of automated high frequency rainfall-runoff monitoring or field survey of stream modifications and geomorphologic changes on riverbeds after extreme events. Using landsat satellite data and aerial photographs we created model of Bark beetle dispersion and clear-cutting between 1985 and 2007. This model enables to describe disturbance dynamic, which is needed for understanding of nature those processes. Next analysis of Landsat satellite data was used to detect the effect of forest disturbance on the wetness and temperature properties of land cover, affected by two significant different types of forest disturbance - bark beetle outbreak and clear cut. The rainfall-runoff analysis using multivariate geostatistical techniques was focused on experimental catchments with similar conditions of climate, physiography and topography but different type

  6. Forest Ecosystem Processes at the Watershed Scale: Ecosystem services, feedback and evolution in developing mountainous catchments

    NASA Astrophysics Data System (ADS)

    Band, Larry

    2010-05-01

    Mountain watersheds provide significant ecosystem services both locally and for surrounding regions, including the provision of freshwater, hydropower, carbon sequestration, habitat, forest products and recreational/aesthetic opportunities. The hydrologic connectivity along hillslopes in sloping terrain provides an upslope subsidy of water and nutrients to downslope ecosystem patches, producing characteristic ecosystem patterns of vegetation density and type, and soil biogeochemical cycling. Recent work suggests that optimal patterns of forest cover evolve along these flowpaths which maximize net primary productivity and carbon sequestration at the hillslope to catchment scale. These watersheds are under significant pressure from potential climate change, changes in forest management, increasing population and development, and increasing demand for water export. As water balance and flowpaths are altered by shifting weather patterns and new development, the spatial distribution and coupling of water, carbon and nutrient cycling will spur the evolution of different ecosystem patterns. These issues have both theoretical and practical implications for the coupling of water, carbon and nutrient cycling at the landscape level, and the potential to manage watersheds for bundled ecosystem services. If the spatial structure of the ecosystem spontaneously adjusts to maximize landscape level use of limiting resources, there may be trade-offs in the level of services provided. The well known carbon-for-water tradeoff reflects the growth of forests to maximize carbon uptake, but also transpiration which limits freshwater availability in many biomes. We provide examples of the response of bundled ecosystem services to climate and land use change in the Southern Appalachian Mountains of the United States. These mountains have very high net primary productivity, biodiversity and water yields, and provide significant freshwater resources to surrounding regions. There has been a

  7. Concentrations and fluxes of dissolved organic carbon in runoff from a forested catchment: insights from high frequency measurements

    NASA Astrophysics Data System (ADS)

    Strohmeier, S.; Knorr, K.-H.; Reichert, M.; Frei, S.; Fleckenstein, J. H.; Peiffer, S.; Matzner, E.

    2012-08-01

    Concentrations of dissolved organic carbon (DOC) in runoff from catchments are often subject to substantial short term variations. The aim of this study was to identify the spatial sources of DOC and the causes for short term variations in runoff from a forested catchment. Furthermore, we investigated the implication of short term variations for the calculation of annual runoff fluxes. High frequency measurements (30 min intervals) of DOC in runoff, of discharge and groundwater table were conducted for one year in the 4.2 km2 forested Lehstenbach catchment, Germany. Riparian wetland soils represent about 30% of the catchment area. The quality of DOC was investigated by three dimensional fluorescence excitation-emission matrices in samples taken from runoff, deep groundwater and shallow groundwater from the riparian wetland soils. The concentrations of DOC in runoff were highly variable at an hourly to daily time scale, ranging from 2.6 mg l-1 to 34 mg l-1 with an annual average of 9.2 mg l-1. The concentrations were positively related to discharge, with a pronounced, counter clockwise hysteresis. Relations of DOC to discharge were steeper in the summer/fall than in the winter/spring season. Dynamics of groundwater table, discharge, DOC concentrations and DOC quality parameters indicated that DOC in runoff originated mainly from the riparian wetland soils, both under low and high flow conditions. The annual export of DOC from the catchment was 84 kg C ha-1 yr-1 when calculated from the high frequency measurements. If the annual export was calculated by simulated random fortnightly samplings, the range was 47 to 124 kg C ha-1 yr-1. Calculations of DOC export fluxes might result in significant errors when based on infrequent (e.g. fortnightly) sampling intervals. Future changes in the precipitation and discharge patterns will influence the DOC dynamics in this catchment, with largest effects in the summer season.

  8. Concentrations and fluxes of dissolved organic carbon in runoff from a forested catchment: insights from high frequency measurements

    NASA Astrophysics Data System (ADS)

    Strohmeier, S.; Knorr, K.-H.; Reichert, M.; Frei, S.; Fleckenstein, J. H.; Peiffer, S.; Matzner, E.

    2013-02-01

    Concentrations of dissolved organic carbon (DOC) in runoff from catchments are often subject to substantial short-term variations. The aim of this study was to identify the compartmental sources of DOC in a forested catchment and the causes for short-term variations in runoff. Furthermore, we investigated the implication of short-term variations for the calculation of annual runoff fluxes. High frequency measurements (30 min intervals) of DOC in runoff, of discharge and groundwater table were conducted for one year in the 4.2 km2 forested Lehstenbach catchment, Germany. Riparian wetland soils represent about 30% of the catchment area. The quality of DOC was investigated by three dimensional fluorescence excitation-emission matrices in samples taken from runoff, deep groundwater and shallow groundwater from the riparian wetland soils. The concentrations of DOC in runoff were highly variable at an hourly to daily time scale, ranging from 2.6 mg L-1 to 34 mg L-1 with an annual average of 9.2 mg L-1. The concentrations were positively related to discharge, with a counter clockwise hysteresis. Relations of DOC to discharge were steeper and the degree of hysteresis larger in the summer/fall than in the winter/spring period. Dynamics of groundwater table, discharge, DOC concentrations and DOC quality parameters indicated that DOC in runoff originated mainly from the riparian wetland soils, both under low and high flow conditions. The annual export of DOC from the catchment was 84 kg C ha-1 yr-1 when calculated from the high frequency measurements. If the annual export was calculated by simulated samplings of >2 days intervals substantial deviations resulted. Predicted changes in precipitation and discharge patterns as well as generally increasing temperatures likely will cause raising DOC exports from this catchment.

  9. Effects of forest harvesting on summer stream temperatures in New Brunswick, Canada: an inter-catchment, multiple-year comparison

    NASA Astrophysics Data System (ADS)

    Bourque, C. P.-A.; Pomeroy, J. H.

    This paper presents a pre- and post-harvest comparison of stream temperatures collected in five neighbouring streams (sub-catchments) over a period of five years (1994-1998). The aim of the study was to determine whether land cover changes from clear cutting in areas outside forest buffer zones (applied to streams >0.5 m wide) might contribute to an increase in summer mean stream temperatures in buffered streams downslope by infusion of warmed surface and sub-surface water into the streams. Specific relationships were observed in all five forest streams investigated. To assist in the analysis, several spatially-relevant variables, such as land cover change, mid-summer potential solar radiation, flow accumulation, stream location and slope of the land were determined, in part, from existing aerial photographs, GIS-archived forest inventory data and a digital terrain model of the study area. Spatial calculations of insolation levels for July 15th were used as an index of mid-summer solar heating across sub-catchments. Analysis indicated that prior to the 1995 harvest, differences in stream temperature could be attributed to (i) topographic position and catchment-to-sun orientation, (ii) the level of cutting that occurred in the upper catchment prior to the start of the study, and (iii) the average slope within harvested areas. Compared to the pre-harvest mean stream temperatures in 1994, mean temperatures in the three streams downslope from the 1995 harvest areas increased by 0.3 to 0.7°C (representing a 4-8% increase; p-value of normalised temperatures <<0.05). The greatest temperature change occurred in the stream that had the greatest proportion of its upper catchment harvested (16.8%), which also had the highest calculated potential solar loading ( ~2749 MJ per stream cell). From the analysis it was determined that the thinning applied to the forest buffer of that stream, with a basal area removal of ~28%, was insufficient to cause significant change in the

  10. Measured and Modeled Water Balances For Three Snow Dominated Forested Catchments With Different Canopy Cover In The Inland Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Hubbart, J. A.; Link, T.; Du, E.

    2007-12-01

    There is a need to better understand the dominant components of the catchment water balance in complex vegetated terrain to advance our understanding of basic hydrological processes and develop effective land management practices. A lack of paired or other detailed watershed studies in the inland Pacific Northwest has limited our understanding of this hydroclimatically, biophysically, and topographically complex region. Empirical analyses of long term data sets, and results from detailed investigations were used to assess impacts of contemporary timber harvest practices on the water balance components of the Mica Creek Experimental Watershed (MCEW). Measurements at the MCEW include precipitation, rainfall interception, snow water equivalent, sap flux, soil moisture, and streamflow. Results were applied to annual averages for the 2002 through 2005 water years directly following canopy removal. Of total precipitation (1401 mm/wy), 755 mm, 628 mm, and 475 mm/yr resulted in streamflow from clearcut, partial cut, and fully forested catchments respectively. Study results showed that canopy interception of rain was 17.2 % of rainfall for a full canopy, and 13.3 % for a partial cut (i.e. 50 % harvest) canopy. Canopy interception of snow was calculated as 43 % and 60 % for partial cut and full forest respectively. Based on sap flow measurements, transpiration was calculated to be 1.5 mm/day for approximately 200 days per year, or 300 mm/year. Based on these findings, estimates of evaporation (including sublimation) were 161 mm, 361 mm, and 470 mm/yr, and estimates of transpiration were 148 mm, 221 mm, and 296 mm/yr, for clearcut, partial cut, and fully forested catchments respectively. This suggests that water yield increased 30 % following clearcut harvest, and 20 % following partial cut harvest, and evaporation dropped to nearly 30 % of pre-harvest evaporation following clearcut, and nearly 60 % of pre-harvest evaporation following partial cut harvest. Soil evaporation

  11. Denitrification and N2O emission in an N-saturated subtropical forest catchment, southwest China

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Mulder, Jan; Dörsch, Peter

    2010-05-01

    Increasing anthropogenic emissions of nitrogen have resulted in locally high deposition rates of reactive nitrogen in China (30-73 kg N ha-1 a-1; Zhang. et al., 2008), primarily as NOx (from fossil fuel combustion) and NH3 (from fertilizer production and animal husbandry). Due to the subtropical, monsoonal climate with high soil temperature and moisture in summer, forests in south China may be expected to show high nitrification and denitrification rates, both of which can cause high N2O emissions. To estimate the N2O source strength and to investigate N-turnover processes relevant for N removal in subtropical forest, we investigated spatiotemporal patterns of N2O emission along a hydrological flowpath from July to November of 2009 in the TSP catchment (Tieshanping), situated close to Chongqing, one of the biggest cities in southwest China. Results from the first study year revealed high N cycling rates and N2O emissions during the wet season, (June to September). Surprisingly, soils on the hill slopes showed higher denitrification potentials and N2O emission rates than the wetter groundwater discharge zone at the bottom of the hill slopes. This was probably due to higher soil bulk density and less organic carbon content in the groundwater discharge zone. Highest denitrification potential were found in the O and A layer (< 5cm) of the hillslopes, suggesting that the organic carbon is the limiting factor for N-removal by denitrification in this ecosystem. High N-removal on the hill slopes was confirmed by decreasing NO3- concentrations along the flowpath during hydrologically stable conditions. However, high NO3- concentrations found in stream water during rain events suggest that the retention time of N in the catchment is too short to allow complete removal by denitrification. N2O emission fluxes dropped by two orders of magnitude in the beginning of the dry season, reflecting lower N input and removal rates during winter. Our results show that denitrification and

  12. Sulfur Mass Balances of Forested Catchments: Improving Predictions of Stream Sulfate Concentrations Through Better Representation of Soil Storage and Release

    NASA Astrophysics Data System (ADS)

    Scanlon, T. M.; Rice, K. C.; Riscassi, A.; Cosby, B. J., Jr.

    2015-12-01

    Sulfur dioxide (SO2) emissions in the eastern United States have declined by more than 80% since 1970, when the Clean Air Act first established limits on emissions from stationary and mobile sources. In many areas throughout the northeastern U.S., the resulting declines in sulfate (SO42-) deposition have been accompanied by declines in stream SO42- concentrations. In the southeastern U.S., however, declines in stream SO42- concentrations have not been observed on a widespread basis. In fact, SO42- concentrations continue to increase in many southeastern streams despite decades of declining deposition. This difference in behavior between northeastern and southeastern streams, owing to the distinct geological histories of their catchment soils, was anticipated by the Direct/Delayed Response Project initiated by the U.S. EPA during the early 1980s. At that time, understanding of how catchments store and release SO42- was mostly grounded in theory. Now, with the accumulation of long-term stream chemistry and hydrological datasets in forested catchments, we may develop an empirical basis for characterizing catchment storage and release of SO42-. In particular, are whole-catchment isotherms that described the partitioning between adsorbed and dissolved SO42- (1) linear or non-linear and (2) reversible or irreversible? How do these isotherms vary on a geographical basis? We apply mass balance combined with a simple theoretical framework to infer whole-catchment SO42- isotherms in Virginia and New England. Knowledge of this key soil geochemical property is needed to improve predictions of how catchments will store and export SO42- under changing levels of atmospheric deposition.

  13. Biogeochemistry of organotin compounds and tin in a forested catchment in Germany.

    PubMed

    Huang, Jen-How; Matzner, Egbert

    2004-10-01

    Organotin compounds (OTC) are highly toxic pollutants that have been shown to affect many aquatic ecosystems. Little is known about the input and fate of OTC in terrestrial ecosystems. Here, soil pools, concentrations and fluxes in bulk precipitation, throughfall, fog, litterfall and runoff of OTC and Sntotal were investigated in a forested ecosystem (Picea abies, Karst.) in NE Bavaria, Germany. The concentrations of OTC and Sntotal were generally in the order fog>throughfall>bulk precipitation. Average concentrations of OTCtotal ranged from 57 ng Sn l(-1) in fog to 5.8 ng Sn l(-1) in bulk precipitation. Concentrations of Sntotal were in the same order but between 490 ng Sn l(-1) in fog and 140 ng Sn l(-1) in bulk precipitation, on average. Average OTCtotal concentrations in litterfall were 12.9 ng Sn g(-1) and those of Sntotal in litterfall 38 ng Sn g(-1). All OTC concentrations in runoff were lower than in bulk precipitation, while those of Sntotal were similar to the concentrations in bulk precipitation. Monobutyltin was the dominating OTC in bulk precipitation, throughfall, fog and litterfall, but was seldom detected in the runoff. The annual total deposition of OTCtotal (calculated as throughfall + litterfall) was 172 mg Sn ha(-1) year(-1), with 45 mg Sn ha(-1) year(-1) represented by litterfall. The annual runoff from the catchment of OTCtotal amounted to 25 mg Sn ha(-1) year(-1). The total deposition of Sntotal was 4.9 g Sn ha(-1) year(-1), of which 0.2 g Sn ha(-1) year(-1) was litterfall. The annual runoff of Sntotal was 2.4 g Sn ha(-1) year(-1). The mass balance showed a high retention of OTC and Sntotal in the catchment. The forest soils act as a strong sink for OTC and Sntotal. Only small amounts of deposited OTC are released to runoff. The ratio of soil pools to annual accumulation for total OTC (46 years) indicates that OTC inputs have been occurring already for many decades or have been substantially higher in the past than today. PMID:15336905

  14. Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Mulder, J.; Wu, L. P.; Meng, X. X.; Wang, Y. H.; Dörsch, P.

    2013-03-01

    Subtropical forests in southern China have received chronically large amounts of atmogenic nitrogen (N), causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O). We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4) at Tieshanping (Chongqing, SW China) and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hillslope (HS) and a hydrologically connected, terraced groundwater discharge zone (GDZ) in the valley bottom. High emission rates of up to 1800 μg N2O-N m-2 h-1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than on HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature (ST) and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3-) in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3- decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.54 and 0.43 g N2O-N m-2 yr-1 for a year with a wet and a dry summer, respectively) are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8-10% of the annual atmogenic N deposition, suggesting that forests on acid soils in southern China are an important, hitherto overlooked component of the anthropogenic N2O budget.

  15. Rainfall-runoff models vs paired catchment models - on comparing two approaches to identify the hydrological impact of forest cover changes

    NASA Astrophysics Data System (ADS)

    Andreassian, V.

    2013-12-01

    There are two basic approaches for analyzing the hydrological impact of forest cover changes: . the oldest is based on the comparison of the so-called 'paired catchments'; . the second is based on the use of a hydrological rainfall-runoff model. In both cases, a model (nature-made in the case of the paired catchments or man-made in the case of the rainfall-runoff approach) is used, and requires calibration on a reference period. Here, we compare both approaches on several well-known experimental forested catchments, in order to identify the limits of each method. Our conclusion is extremely clear: wherever an appropriate paired catchment can be found, the paired-catchment model should be preferred, because it allows avoiding the many uncertanties linked with the non-linear complexities of the rainfall-runoff transformation.

  16. Spatially distributed soil water content in a small forested catchment and its relation to the catchment water budget on various timescales

    NASA Astrophysics Data System (ADS)

    Graf, Alexander; Bogena, Heye R.; Hardelauf, Horst; Pütz, Thomas; Drüe, Clemens; Heinemann, Günther; Vereecken, Harry

    2014-05-01

    In the framework of the TERENO project, terrestrial observatories have been implemented in order to observe hydrological phenomena at several scales, from small highly instrumented headwater catchments to mesoscale watersheds. At the headwater catchment scale, field experiments are conducted in which the effects of land use change are monitored to provide empirical data describing hydrological processes and responses. The TERENO test site Wüstebach is a 38.5 ha small forested headwater catchment located in a low mountain range in Germany. For a period of 3 years prior to a partial deforestation in 2013, the catchment hydrology has been characterized by continuous measurements of runoff (R), actual evapotranspiration based on the eddy-covariance method (ET), and soil water content at 3 depths in 109 locations (θ). With nearby measurements of precipitation (P), as well as potential evapotranspiration (PET) for regression-based gap filling of ET, it was possible to analyse the water budget without relying on process-based models. The long-term water budget P-ET-R was closed with a residual of less than 3% of annual precipitation. On the daily timescale, the increasing residual of the water budget was explained to a moderate extent by soil water content (R² = 0.40). Wavelet coherence analysis revealed timescales of about 4 days and less, which were presumably dominated by unaccounted fast-turnover storage terms such as interception, as a major source of uncertainty. At weekly resolution, soil water storage explained more than half (R² = 0.62) of the water budget residual. By means of a combined empirical orthogonal function and cluster analysis, differences in the spatial pattern of soil water content between wet and dry state (above and below 0.35 cm³/cm³ spatially averaged soil water content) of the catchment could be identified. Various analyses confirmed that ET was predominantly energy-limited, but gradually lost coherence with PET and thus energy supply

  17. Headwater thermal response to partial-retention forest harvesting: a process-based paired-catchment experiment

    NASA Astrophysics Data System (ADS)

    Moore, R. D.; Guenther, S. M.; Gomi, T.

    2008-12-01

    Paired-catchment experiments are the most rigorous empirical research design for estimating the effects of land use on aquatic systems. However, they have recently come under increasing criticism, in part because past studies typically treated catchments as black boxes. As a result, investigators could only speculate about the factors responsible for any observed effects, limiting their ability to generalize the experimental results in space and time. This study used a paired-catchment approach to investigate the effects of partial- retention forest harvesting with no riparian buffer on the thermal regime of a headwater stream in coastal British Columbia. In addition to monitoring stream temperature at three locations within the treatment reach, we monitored above-stream microclimate, water surface evaporation, bed temperature profiles, groundwater temperature, and reach-scale surface-subsurface interaction. Daily maximum stream temperatures increased after harvesting by over 5 °C during summer, with little effect in winter. The major driver of post- harvest warming was an increase in solar radiation, which was partially moderated by the increased effects of hyporheic exchange, bed heat conduction and evaporation. Incorporating process-based measurements into paired-catchment experiments not only allows the causes of treatment response to be assessed, but they provide a valuable data set for testing predictive models.

  18. Investigating Runoff Generation in a Headwater Forested Catchment Using a Typology of Nonlinear Storage-Discharge Relationships

    NASA Astrophysics Data System (ADS)

    L'Heureux, C.; Ali, G. A.; Roy, A. G.; Turmel, M.; Courchesne, F.

    2011-12-01

    We investigated the "switching on and off" of runoff generation in a small forested catchment, the Hermine, characterized by moderately steep surface topography and an extensive but discontinuous fragipan-like horizon at an average depth of 0.75 m within the soil mantle. A water table dataset (94 wells, 50 sampling campaigns) was used to derive point-scale perched groundwater (PGW) storage variables illustrating the presence or absence of surface water, the soil deficit to saturation, the location of dry, filling and spilling subsurface hollows, and the water table elevation above an underlying filled subsurface hollow. A typology of storage-discharge relationships was also built to differentiate locations driven by threshold-crossing between two extreme states from other locations experiencing a continuum of hydrologic states. We found that spatial patterns of PGW storage were initially important during a rainstorm to trigger a response at the catchment outlet but then remained unchanged even though streamflows continued to increase up to an order of magnitude higher. While discontinuous storage-discharge relationships were observed at the point-scale, continuous relationships were rather observed at the aggregated catchment-scale, thus implying that the emergent catchment behaviour could be described as a continuum of hydrological states. At the point-scale, storage-discharge relationships were used to assess the spatial heterogeneity of runoff processes as their associated shapes and thresholds indicated the timing of either preferential flow activation or subsurface connectivity enhancement. At the catchment scale, a critical outflow parameter of 1 L.s-1 was found to transcend small-scale process heterogeneity as it signalled the triggering of the catchment internal stormflow generation mechanisms. Our typology of nonlinear relationships was especially useful for grouping similar runoff responses both in space and time. We therefore make a plea for cross

  19. Annual Dynamics of Green House Gases in a Swedish Boreal Forested Catchment

    NASA Astrophysics Data System (ADS)

    Oquist, M. G.; Klemedtsson, L.; Bishop, K.; Grip, H.; Laudon, H.; Nilsson, M.

    2003-04-01

    We investigated the spatial and temporal variation of CO_2, CH_4 and N_2O in a boreal forested catchment with respect to their atmospheric exchange and their below-ground concentration dynamics. The measurements were carried out at three sites distributed along a gently sloping 22 m transect draining into a small creek. Vegetation was dominated by a 95 year old Norway spruce stand and soil types ranged from organic (a riparian zone histosol) to mineral (podzol on sandy till). Soil gas concentrations (at 5, 10, 20, 40 and 60 cm depth) were measured weekly for 18 months, while gas fluxes were measured weekly during the snow-free season and at 4 campaigns during the winter season. During the growing season average CO_2 efflux from the three sites ranged from 0.7--1.8 g m-2 d-1, while CH_4 displayed a net uptake rate of 0.1--0.3 mg m-2 d-1. Detectable amounts of N_2O emissions appeared sporadically, but never exceeded 0.04 mg m-2 d-1. The variation in CO_2 flux had the same temporal pattern as the variation in soil temperature (5--25 cm depth; r^2 = 0.6--0.85), while ca 40% of the differences in CH_4 consumption could be accounted for by the variations in soil moisture in the top 20 cm. During winter, fluxes of CO_2 and CH_4 were of the same order of magnitude as during summer, but the N_2O emissions were considerably higher, averaging around 0.4 mg m-2 d-1. Furthermore, soil gas concentrations of N_2O during winter showed a strong positive temperature correlation with a ca10-fold increase in concentration per ^oC (r^2 = 0.93). Our results stress the importance of the winter season for the greenhouse gas dynamics of the boreal landscape, and also that both N_2O and CH_4 exchange have the potential to influence how these ecosystems interact with the Earth's radiative balance. Moreover, the strength of atmospheric CH_4 consumption rates in these systems appears to be indifferent to season, which has implications for regional estimates of CH_4 budgets. The temperature

  20. The transformations and fates of deposited N in an N saturated subtropical forested catchment, SW China

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Mulder, Jan; Dörsch, Peter

    2015-04-01

    Subtropical forests in south China are receiving long-term elevated nitrogen (N) deposition. Previous field observations in the N-saturated forested headwater catchment at Tieshanping (TSP), Chongqing, SW China, found apparent fast NH4+ disappearance in the top soil on the hillslope, but lab incubation for nitrification potentials did not support such disappearance. Meanwhile, large unaccounted N sinks were suggested by fast NO3- disappearance along the flow path in the groundwater discharge zone (GDZ), possibly due to denitrification and subsequent N2 emission. In this study, we investigated the fates of deposited N (mainly in the forms of NH4+ and NO3-) and the nature of the N transformations using isotopic tracer approach. 15N-labeled NH4+ or NO3- (99 atom% 15N) were amended to repacked surface soil columns from the hillslope and GDZ of TSP. The changes of the N forms of NH4+, NO3-, dissolved organic N, microbial biomass N and bulk N in soil were traced in a period of 15 days, representing transient (0.5 hr, 6 hr and 1 day) and mid-term (5 days and 15 days) N transformations. The soil moistures were kept at the typical field conditions (55% and 95% WFPS for hillslope soil and GDZ soil, respectively). Opposite to the field observations, the amount of added NH4+ decreased gradually on hillslope. 85% and 30% of the added 15N-NH4+ kept in the form of NH4+ after 1 day and 15 days. 15N-NO3- was produced gradually on hillslope, up to 26% of added 15N-NH4+ after 15 days incubation. About half of the added 15N-NH4+ was incorporated to organic N. The added 15N-NO3- showed a similar picture, with 55% left in the soil of hillslope after the whole incubation. Interestingly, although soil in GDZ had much higher WFPS, the nitrification rate of it was much higher than that on hillslope. Apparently the added 15N-NH4+ was incorporated immediately into organic matter in GDZ soil and being denitrified gradually along the time. The incorporation of the added 15N-NO3- into soil

  1. Radioactive Cs-137 discharge from Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    NASA Astrophysics Data System (ADS)

    Iwagami, S.; Onda, Y.; Tsujimura, M.; Sakakibara, K.; Konuma, R.

    2015-12-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, Cs-137 concentration of dissolved water, suspended sediment and coarse organic matter such as leaf and branch were monitored. Discharge amount of stream water, suspended sediment and coarse organic matter were measured to investigate the discharge amount of radiocesium and composition of radiocesium discharge form through the headwater stream. Observation were conducted at stream site in four headwater catchments in Yamakiya district, located ~35 km north west of FDNPP from June 2011 (suspended sediment and coarse organic matter: August 2012) to December 2014.The Cs-137 concentration of dissolved water was around 1Bq/l at June 2011. Then declined to 0.1 Bq/l at December 2011. And in December 2014, it declined to 0.01 Bq/l order. Declining trend of Cs-137 concentration in dissolved water was expressed in double exponential model. Also temporary increase was observed in dissolved Cs-137 during the rainfall event. The Cs-137 concentration of suspended sediment and coarse organic matter were 170-49000 Bq/kg and 350-14000 Bq/kg respectably. The Cs-137 concentration of suspended sediment showed good correlation with average deposition density of catchment. The effect of decontamination works appeared in declining of Cs-137 concentration in suspended sediment. Contribution rate of Cs-137 discharge by suspended sediment was 96-99% during a year. Total annual Cs-137 discharge from the catchment were 0.02-0.3% of the deposition.

  2. 45 years of non-stationary hydrology over a forest plantation growth cycle, Coalburn catchment, Northern England

    NASA Astrophysics Data System (ADS)

    Birkinshaw, Stephen J.; Bathurst, James C.; Robinson, Mark

    2014-11-01

    The Coalburn research catchment (1.5 km2) in Kielder Forest, Northern England, is a long-term project to study the effect of upland afforestation on hydrology. There is now a unique 45-year record; making it Britain's longest running forest hydrology research catchment. The site was instrumented in 1967, ploughed and planted in 1972/73 and the trees have now reached maturity. Hourly meteorological data have been measured since 1993 and these have enabled hydrological simulations to be carried out using the Shetran model for the period 1993-2011. The results from this work show that after ploughing there was an increase of around 50-100 mm in annual streamflow compared with the original upland grassland vegetation. However, the mature trees now show a decrease of around 250-300 mm in the annual streamflow compared with the original vegetation and a decrease of around 350 mm in the annual streamflow compared with when the site was ploughed. The simulation results show very clearly the non-stationary nature of the catchment during 1993-2011 with an annual increase in intercepted evaporation and a decrease in discharge as the trees grow. Simulation results also show that peak discharges are higher for a cover of smaller trees compared with taller trees. However, the results suggest that the bigger the event the smaller is the difference, i.e. there is absolute convergence for the two different tree scenarios at higher discharges. The study shows how modelling can compensate for data deficiencies, to maximise outcomes. As a rare example of long-term analysis of non-stationary catchment behaviour it also provides real evidence of change that would otherwise have had to be inferred theoretically.

  3. Terrestrial and in-stream influences on the spatial variability of nitrate in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Scanlon, Todd M.; Ingram, Spencer M.; Riscassi, Ami L.

    2010-06-01

    A vast majority of monitoring programs designed to assess nutrient fluxes from headwater systems rely upon temporally intensive sampling at a single position within the stream network, essentially measuring the integrated response of the catchment. Missing from such an approach is spatial information related to how nutrient availability varies throughout the network, where freshwater biota live and where biogeochemical processes ultimately shape the downstream water chemistry. Here, we examine the spatial distribution of nitrate (NO3-) concentrations within the Paine Run catchment, a forested headwater catchment in Shenandoah National Park, Virginia. Nitrate concentrations throughout the stream network were measured as part of synoptic surveys conducted in 1992-1994, in the aftermath of region-wide gypsy moth defoliation that caused dramatic increases in stream water NO3- concentrations. A follow-up synoptic survey was conducted in 2007, when the stream water NO3- concentrations had returned to predefoliation levels. Common to each of the eight synoptic surveys were observations of multiple-fold declines in NO3- concentration along the main stem of the stream network from the headwaters to the catchment outlet. A portion of this decline was caused by dilution, as water input by tributaries at the lower elevations of the catchment tended to have lower NO3- concentrations. A stream network model was applied to determine the relative contributions of terrestrial versus in-stream processes to the spatial variability of the NO3- concentrations. Model results suggest that even though nitrate removal within the stream network can be substantial, terrestrial factors that determine the NO3- inputs to streams account for the vast majority of the spatial variability in stream water NO3- concentrations.

  4. Hydrological Controls on Nitrogen and DOC Transport at the Plot, Hillslope and Catchment Scale, HJ Andrews Experimental Forest.

    NASA Astrophysics Data System (ADS)

    van Verseveld, W. J.; McDonnell, J. J.; Lajtha, K.

    2005-12-01

    While the flushing of nutrients at the catchment scale has been described in many forested environments during the last decade, the flushing mechanisms, flowpaths and geographic sources of different N species (DON, NO3- and NH4+) and DOC are still poorly resolved, especially during different storm size and antecedent wetness conditions. We characterized flowpaths of N and DOC at the hillslope scale during and between storm events in WS10, H.J. Andrews, Oregon, USA, for five storms over the period Fall 2004 until Spring 2005. This catchment is dominated by hillslopes with negligible riparian water storage due to 1986 and 1996 debris flows that evacuated the valley bottom. This enabled us to study the hydrological and biogeochemical coupling between the hillslope and catchment in a way unimpeded by riparian zone groundwater dynamics.Through a combination of hydrometric and chemistry data from groundwater wells, tension and zero tension lysimeters at different depths, tensiometers, soil moisture probes and hillslope runoff from a 10 meter wide trench at the hillslope, we were able to resolve the dominant flowpaths. Fluorescence (a proxy for DOC) of hillslope and catchment runoff was monitored continuously with a fluorometer during storms. Preliminary data analysis showed a significant relationship between DOC concentrations and fluorescence values suggesting that fluorescence can be used to characterize DOC dynamics at small time scales. Our high frequency DOC characterization showed a clockwise hystersis pattern of DOC and total N against discharge for both hillslope and catchment runoff. This suggests flushing of nutrients in near and/ or in stream zones during the initial part of the storm. Total N and DOC concentrations in groundwater wells and lysimeters at shallow soil depths were high compared to other potential sources during storms. Our interpretation is that vertical preferential flow of high concentration water drives the groundwater contribution to

  5. Seasonal changes in streamwater concentration and pathways of phosphorus in a forested catchment under a temperate climate

    NASA Astrophysics Data System (ADS)

    Verheyen, Dries; Van Gaelen, Nele; Ronchi, Benedicta; Govers, Gerard; Merckx, Roel; Batelaan, Okke; Struyf, Eric; Diels, Jan

    2014-05-01

    In forest ecosystems phosphorus (P) is regarded to be among the most limiting nutrients. Therefore, P is cycled in an almost closed system, so that losses of P are minimal. Litterfall and leaf decomposition are key processes that control nutrient dynamics between forest and river systems and can cause losses of P. It is important to understand the dynamics and seasonal variations of P because P input-output balances can have an effect on sustainability of forest ecosystems. A forested headwater catchment (230 ha) has been monitored for different fractions of dissolved (<0.45 µm) P concentration in the river and in soil- and groundwater from January 2011 until December 2013. The P measurements consisted of dissolved reactive P with colorimetry and total dissolved P with ICP-OES. Base flow samples were taken twice a week and when discharge events occurred, samples were taken flow proportional with an ISCO sampler. Leaf decomposition was measured in a column test under different fluxes of water to assess P fluxes out of the decomposition of the litter layer. The yearly flux of P out of the catchment was on average 0.2 kg P.ha-1.y-1. There was a clear difference in total P concentration between summer and winter in the river water. In winter, the concentrations were low (<0.2 mg P/l), even when a rainfall event occurred. In summer, concentrations of total P rose up to 0.6 mg P/l in the base flow. In the peak flow they lowered due to dilution effects. The rise in P concentration in the base flow in summer could only be attributed to in-river processes, because no hydrologic pathway of P reaching the river could explain this particular rise in concentration. Concentrations of P remained low in groundwater (0.035 ± 0.039 mg P/l) and soil water (0.021 ± 0.14 mg P/l) during the 3 years of measurements. A hypothesis is that the breakdown of leaf litter aided by temperature driven microbial activity can be accounted for this rise and can deliver up to half of the flux of P

  6. Spatial pattern of dissolved organic matter (DOM) along a stream drainage in a forested, Piedmont catchment

    NASA Astrophysics Data System (ADS)

    Inamdar, S. P.; Singh, S.

    2013-12-01

    Understanding how dissolved organic matter (DOM) varies spatially in catchments and the processes and mechanisms that regulate this variation is critical for developing accurate and reliable models of DOM. We determined the concentrations and composition of DOM at multiple locations along a stream drainage network in a 79 ha forested, Piedmont, watershed in Maryland, USA. DOM concentrations and composition was compared for five stream locations during baseflow (drainage areas - 0.62, 3.5, 4.5, 12 and 79 ha) and three locations (3.5, 12, 79 ha) for storm flow. Sampling was conducted by manual grab samples and automated ISCO samplers. DOM composition was characterized using a suite of spectrofluorometric indices which included - HIX, a254, and FI. A site-specific PARAFAC model was also developed for DOM fluorescence to determine the humic-, fulvic-, and protein-like DOM constituents. Hydrologic flow paths during baseflow and stormflow were characterized for all stream locations using an end-member mixing model (EMMA). DOM varied notably across the sampled positions for baseflow and stormflow. During baseflow, mean DOC concentrations for the sampled locations ranged between 0.99-3.1 mg/L whereas for stormflow the range was 5.22-8.11 mg/L. Not surprisingly, DOM was more humic and aromatic during stormflow versus baseflow. The 3.5 ha stream drainage location that contained a large wetland yielded the highest DOC concentration as well as the most humic and aromatic DOM, during both, baseflow and stormflow. In contrast, a headwater stream location (0.62 ha) that received runoff from a groundwater seep registered the highest mean value for % protein-like DOM (30%) and the lowest index for aromaticity (mean a254 = 6.52) during baseflow. During stormflow, the mean % protein-like DOM was highest at the largest 79 ha drainage location (mean = 11.8%) and this site also registered the lowest mean value for a254 (46.3). Stream drainage locations that received a larger proportion

  7. Hydrological controls on denitrification in riparian zone of forested headwater catchment: Soil physical properties make difference in reduced environment

    NASA Astrophysics Data System (ADS)

    Ohte, N.; Watanabe, Y.; Oda, T.; Osaka, K.

    2010-12-01

    Riparian zone near stream plays important roles to control the solute discharge from hillslope to stream. Supply of inorganic nitrogen as an essential nutrient of aquatic primary producers is generally regulated by hydrological and biogeochemical processes such as denitrification in this unique landscape unit in headwaters. To elucidate how the denitrification is controlled by hydrological properties of riparian groundwater aquifer, we investigated two similar scaled forested headwater catchments with different soil physical properties in Japan. The Kiryu- Matsuzawa catchment (KEW, 0.6 ha) has weathered granitic bedrock, and its soils in riparian zones are sandy, while the Fukuroyama-sawa catchment (FEW, 1.1 ha) has Tertiary sedimentary bedrock, and has clayey soils. Concentrations, δ15N and δ18O of NO3- in soil water, groundwater and streamwater were monitored during 2007 - 2009. Enrichment in δ15N-NO3- was found in the perennial groundwater bodies both in KEW and FEW, indicating active denitrification occurred (Fig 1). In the same time, however, increase in δ18O-NO3- of KEW groundwater was unclear, while that of FEW was found clearly indicating the denitrification under a closed system without significant dissolved O2 (DO) and new NO3- supply. It was also suggested that the denitrification in the KEW groundwater occurred under condition with relatively high DO, and new NO3- recharge by lateral groundwater movement. These differences were explainable by hydrological features of soils holding groundwater: The mean residence time (MRT) of the groundwater in FEW was estimated as three times longer (>1000 days) than that in KEW (<300 days). Moreover, this difference in MRT of groundwater aquifer is essentially caused by difference in the soil water retention characteristics between sandy soil in KEW and clayey soil in FEW. Those indicated the possibility that the difference of soil physical properties can be reflected strongly on inorganic nitrogen discharge from

  8. Temporal variation in end-member chemistry and its influence on runoff mixing patterns in a forested, Piedmont catchment

    NASA Astrophysics Data System (ADS)

    Inamdar, Shreeram; Dhillon, Gurbir; Singh, Shatrughan; Dutta, Sudarshan; Levia, Delphis; Scott, Durelle; Mitchell, Myron; Stan, John; McHale, Patrick

    2013-04-01

    Runoff mixing patterns for base flow and 42 storm events were investigated for a 3 year period (2008-2010) in a 12 ha forested catchment in the mid-Atlantic, Piedmont region of the USA. Eleven distinct runoff sources were sampled independently and included: precipitation, throughfall, stemflow, litter leachate, wetland soil water, tension soil water, shallow groundwater, groundwater seeps, hyporheic water, riparian groundwater, and deep groundwater. A rigorous end-member mixing analysis (EMMA) was implemented and all base flow, storm-flow, and end-member chemistries were evaluated in a two-dimensional mixing space. End-members enclosed stream water chemistry and displayed a systematic continuum in EMMA space. Base-flow chemistry of stream waters was similar to groundwater seeps. Storm-event runoff was attributed to contributions from surficial sources (precipitation, throughfall, stemflow, and litter leachate) on the rising limb of the discharge hydrograph that was followed by soil and shallow groundwater sources on the recession limb of the hydrograph. The shapes of the storm-event hysteresis loops (wide versus tight, linear patterns) varied with hydrologic conditions from wet, hydrologically well-connected conditions to a dry, disconnected state. Detailed temporal data on end-member chemistry allowed us to explain the changes in stream water hysteresis patterns and runoff mixing space to shifts in end-member chemistry that occurred as the catchment became hydrologically disconnected. These results highlight the need to recognize the temporal variation in end-member chemistry as a function of catchment wetness and the need to collect high-frequency data on both--stream water as well as potential runoff end-members to better characterize catchment flow paths and mixing responses.

  9. Chemical Composition of Aquatic Dissolved Organic Matter in Five Boreal Forest Catchments Sampled in Spring and Fall Seasons

    SciTech Connect

    Schumacher,M.; Christl, I.; Vogt, R.; Barmettler, K.; Jacobsen, C.; Kretzschmar, R.

    2006-01-01

    The chemical composition and carbon isotope signature of aquatic dissolved organic matter (DOM) in five boreal forest catchments in Scandinavia were investigated. The DOM was isolated during spring and fall seasons using a reverse osmosis technique. The DOM samples were analyzed by elemental analysis, FT-IR, solid-state CP-MAS {sup 13}C-NMR, and C-1s NEXAFS spectroscopy. In addition, the relative abundance of carbon isotopes ({sup 12}C, {sup 13}C, {sup 14}C) in the samples was measured. There were no significant differences in the chemical composition or carbon isotope signature of the DOM sampled in spring and fall seasons. Also, differences in DOM composition between the five catchments were minor. Compared to reference peat fulvic and humic acids, all DOM samples were richer in O-alkyl carbon and contained less aromatic and phenolic carbon, as shown by FT-IR, {sup 13}C-NMR, and C-1s NEXAFS spectroscopy. The DOM was clearly enriched in {sup 14}C relative to the NBS oxalic acid standard of 1950, indicating that the aquatic DOM contained considerable amounts of organic carbon younger than about 50 years. The weight-based C:N ratios of 31 {+-} 6 and the {delta}{sup 13}Cvalues of -29 {+-} 2{per_thousand}indicate that the isolated DOM is of terrestrial rather than aquatic origin. We conclude that young, hydrophilic carbon compounds of terrestrial origin are predominant in the samples investigated, and that the composition of the aquatic DOM in the studied boreal forest catchments is rather stable during low to intermediate flow conditions.

  10. Denitrification potential of organic, forest and grassland soils in the Ribble-Wyre and Conwy River catchments, UK.

    PubMed

    Sgouridis, Fotis; Ullah, Sami

    2014-07-01

    Soil denitrification activity can be highly variable due to the effects of varied land use management practices within catchments on the biogeochemical regulators of denitrification. To test this assumption in the context of mixed-use rural catchments, it was hypothesised that the relative magnitude of denitrification activity may be regulated, among others, by a gradient of soil nitrate (low to high) between organic (peat bog, heathland, and acid grassland), forest (coniferous and deciduous), and grassland (improved and semi-improved) rural land use types. The denitrification potential (DP) of organic, forest and grassland soils, in two UK catchments was measured in the laboratory. Land use type significantly (p < 0.05) influenced the DP, which ranged between 0.02 and 63.3 mg N m(-2) h(-1). The averaged DP of organic and forest soils (1.08 mg N m(-2) h(-1)) was 3 and 10 times less than the DP of semi-improved (4.06 mg N m(-2) h(-1)) and improved (12.09 mg N m(-2) h(-1)) grassland soils, respectively; and among others, nitrate correlated positively (p < 0.05) with the DP. The results indicated that the difference in soil nitrate concentration between organic (naturally low in nitrate availability) and grassland soils (nitrate enriched due to land management) partially regulated the extent of DP. In the absence of N fertilisation, except for the atmospheric N deposition, the relatively low net nitrification potential (as a source of nitrate for denitrifiers) of organic and forest soils alone seem to have resulted in lower denitrifier's activity compared to grassland soils. Moreover, the interactions between soil organic carbon, pH, bulk density, water filled pore space, and texture, as these are influenced by the relative degree of land management, exerted additional controls on the DP. The results suggest that land management can have significant effects on denitrification, and thus needs to be considered when modelling and/or predicting the response of

  11. The effect of nitrate addition on abundance of nirK, nirS and gln genes in acidified Norway spruce forest soil

    NASA Astrophysics Data System (ADS)

    Bárta, Jiří; Tahovská, Karolina; Kaåa, Jiří; Antrå¯Čková, Hana Å.

    2010-05-01

    The denitrification is the main biotic process leading to loses of fixed nitrogen as well as removal of excess of nitrate (NO3-) from the soil environment. The reduction of NO2- to nitric oxide (NO) distinguishes the 'true' denitrifiers from other nitrate-respiring bacteria. This reaction is catalyzed by two different types of nitrite reductases, either a cytochrome cd1 encoded by nirS gene (nirS denitrifiers) or a Cu-containing enzyme encoded by nirK gene (nirK denitrifiers). The nirS denitrifiers are located mostly in rhizosphere, while the nirK denitrifiers are more abundant in bulk soil. These two groups can be also classified as markers of denitrification. Glutamine synthetase is one of the main bacterial NH4+ assimilating enzymes; it is coded by glnI gene. Glutamine synthetase is mostly active when N is the limiting factor for bacterial growth. There is recent evidence that the activity may be affected by the presence of alternative N source (i.e. NO3-). However, in anaerobic condition NO3- can be used also by the denitrifying bacteria so there may be strong competition for this nutrient. The laboratory experiment was performed to evaluate the effect of nitrates (NO3-) on abundance of nirK, nirS and gln gene copy numbers. The amount of NO3- corresponded to the actual atmospheric depositions on experimental sites in the Bohemian Forest. Litter organic layer (0-5cm of soil) was used for laboratory incubation experiment. Four replicates of control (no addition of NO3-), and NO3-addition were incubated anaerobically for one month. After the incubation DNA was extracted and the number of nirK, nirS and gln gene copies was determined using qPCR (SYBRGreen methodology). Results showed that the addition of NO3- significantly increased the number of nirK and nirS denitrifiers from 5.9x106 to 1.1x107 and from not detectable amount to 1.4x106, respectively. The gln gene copy number was also higher after NO3-addition. However, the difference was not statistically

  12. Influence of climate, fire severity and forest mortality on predictions of long term streamflow: Potential effect of the 2009 wildfire on Melbourne's water supply catchments

    NASA Astrophysics Data System (ADS)

    Feikema, Paul M.; Sherwin, Christopher B.; Lane, Patrick N. J.

    2013-04-01

    SummaryIn February 2009, wildfire affected nine catchments, or approximately 28% of forested catchment area that supplies water to the city of Melbourne, Australia. This has potential to significantly affect the long term water use of these Eucalyptus forests and the consequential water yield because of the ecohydrologic response of some eucalypt species. Approximately 11% of the catchment area was severely burnt by intense fire, where vegetation mortality is higher. Catchment scale models using a physically-based approach were developed for the fire-affected water supply catchments. Different inputs of climate and forest mortality after fire were used to examine the relative contributions of rainfall, fire severity, forest type and forest age on post-fire streamflow. Simulations show the effect of fire on long term streamflow is likely to depend on a number of factors, the relative influence of which changes as rainfall becomes more limiting. Under average rainfall conditions, total reduction in post-fire streamflow after 100 years estimated to be between 1.4% (˜12 GL year-1) and 2.8% (˜24 GL year-1) are an order of magnitude lower than reductions in total catchment inflow during the period of low rainfall between 1997 and 2009, in which reservoir inflow was reduced by nearly 37%. The main reasons for the lower than expected changes in water yield are that a lower proportion of the catchments were affected by severe fire, and so mortality within the fire area was relatively low, and that the average age of the forest canopy (93 years) is younger than what is generally considered old growth forest. This means that the baseline (no-fire) streamflow used for reference is lower than would be expected with older, mature forest. The greatest post-fire affect on total water yield was predicted for the O'Shannassy catchment. This is due to the average forest age, which is the oldest of any of the catchments, that it has the highest average rainfall (1680 mm year-1), and

  13. Element export from a small catchment in the tropical montane forest of Ecuador responds to climate change

    NASA Astrophysics Data System (ADS)

    Leimer, Sophia; Willimann, Elias; Alaoui, Abdallah; Trachte, Katja; Wilcke, Wolfgang

    2015-04-01

    In a very remote tropical montane rain forest in the Ecuadorian Andes on the rim of the Amazon basin, increasing temperatures, longer dry spells, and an associated reduction in soil moisture were observed in the past 15 years. In the study ecosystem, element exports from a 9-ha large catchment with stream water are linked to the depth of water flow through soil because of vertical variations in soil chemical properties. The further increase in temperature and precipitation, as predicted by climate models, will have an impact on the water flow paths in soil and therefore alter element exports. Hence, we investigated how future element exports from this catchment in Ecuador will develop under the emission scenarios A1B and B1 for the decades 2050-2059 and 2090-2099 compared to current element exports. Discharge from the study catchment was measured in 1998-2013, partly in high resolution. Element concentrations in stream water (total organic carbon, NO3-N, NH4-N, dissolved organic nitrogen, PO4-P, total dissolved phosphorus, S, Cl, K, Ca, Mg, Na, Zn, Al, Mn) were measured in 1998-2012 in weekly resolution. Based on catchment properties, measured climate, and water flow data, discharge in 1998-2013 was simulated in daily resolution with the hydrological model WaSiM. From the hydrograph of surface flow, three flow classes (baseflow, intermediate, storm) were separated and linked with stream chemical properties. Element concentrations in stream water were grouped according to the flow classes and mean concentrations per flow class were calculated. Subsequently, the mean element concentration was multiplied with the mean of the annual discharge sums per flow class resulting in current element exports. For estimations of future element exports with stream water, discharge was simulated under the emission scenarios A1B and B1 for the decades 2050-2059 and 2090-2099 and separated into the three flow classes. Future element exports per scenario were calculated according to

  14. The Seasonal Evolution of Hillslope-Channel Connectivity in a Flashy Forest Catchment

    NASA Astrophysics Data System (ADS)

    Elsenbeer, H.; Zimmermann, A.

    2008-12-01

    Fast, near-surface flowpaths are a trait of soilscapes with high rainfalls amounts and intensities and with an abrupt decrease of permeability with depth. The Lutz Creek catchment in Panama is a prime example of such an environment, in which overland flow generated at the soil surface proper and return flow (RF) connect hillslopes with its stream channels. Return flow- and saturation overland flow (SOF)-mediated connectivity is, however, not arranged randomly, but follows a topography-controlled pattern. This pattern, in turn, determines a temporal pattern of connectivity: RF-prone parts of the catchment connect hillslopes and channels earlier in the wet season than do SOF-prone parts, and regardless of season, the former establish connectivity in response to low-intensity rainfall, whereas the latter require high-intensity rain, all else being equal. Increasing catchment wetness towards the end of the wet season, however, blurs the distinction between RF- and SOF-controlled parts of the catchment, and this is when maximal connectivity is achieved.

  15. Solute Dynamics in a Near-Surface Flowpath-Dominated Forest Catchment

    NASA Astrophysics Data System (ADS)

    Zimmermann, A.; Turner, B. L.; Elsenbeer, H.

    2008-12-01

    Near-surface flowpaths are common in soilscapes that show a pronounced decrease in permeability and that are subject to high rainfall amounts and intensities; Lutz Creek catchment in tropical Panama is no exception. In this catchment, landscape position and antecedent wetness dictate whether overland flow is generated by saturation excess (SOF) or by return flow (RF). In an ongoing study we explore the consequences of these topography-controlled modes of overland flow generation for solute dynamics at different scales: catchment scale and nested subcatchment scale. Total dissolved nitrogen, for example, is higher in RF-dominated than in SOF-dominated subcatchments. Potassium, in contrast, shows higher concentrations in SOF than in RF, and SOF resembles throughfall in this respect, whereas RF does not. Calcium is equally suitable to distinguish between SOF and throughfall on the one hand, and RF on the other. Accordingly, RF-dominated subcatchments show a dynamic within-event response whereas the calcium signal is nearly flat in SOF- controlled subcatchments. We conclude that the topography-controlled and flowpath-mediated hydrochemical signals persist over the extent of our research catchment.

  16. THE DOWNSLOPE PROPAGATION OF A DISTURBANCE IN A FORESTED CATCHMENT: AN ECO-HYDROLOGIC SIMULATION STUDY

    EPA Science Inventory

    We developed and applied a spatially-explicit, eco-hydrologic model to examine how a landscape disturbance affects hydrologic processes, ecosystem cycling of C and N, and ecosystem structure. We simulated how the pattern and magnitude of tree removal in a catchment influences fo...

  17. Synchronicity of long-term nitrate patterns in forested catchments across the northeastern U.S.

    EPA Science Inventory

    Nitrogen movement through minimally-disturbed catchments can be affected by a variety of biogeochemical processes, climatic effects, hydrology and in-stream or in-lake processes. These combine to create dizzying complexity in long-term and seasonal nitrate patterns, with adjacen...

  18. Spatial Distribution of Surface Soil Moisture in a Small Forested Catchment

    EPA Science Inventory

    Predicting the spatial distribution of soil moisture is an important hydrological question. We measured the spatial distribution of surface soil moisture (upper 6 cm) using an Amplitude Domain Reflectometry sensor at the plot scale (2 × 2 m) and small catchment scale (0.84 ha) in...

  19. Ecosystem processes at the watershed scale: Geomorphic patterns and stability of forest catchment water, energy and nitrogen use efficiency in the southern Appalachians

    NASA Astrophysics Data System (ADS)

    Band, L. E.; Hwang, T.; Hales, T. C.; Ford, C. R.

    2012-12-01

    Since the classic work by Hack in Goodlett in 1960, it has been recognized that there is a close coupling of geomorphic, forest ecosystem and soil development in humid mountainous catchments, with the magnitude and frequency of mass wasting events. In the southern Appalachians of the southeast United States, dense forest cover limits erosion and sediment transport during moderate events in undisturbed catchments, with most sediment delivery to streams by mass wasting processes, including the interaction of diffusive processes (soil creep) and debris avalanches. We hypothesize that debris avalanches are frequently triggered in a zone with moderate concavity at the head or just above hollows where a critical combination of sufficient gradient, colluvial soil accumulation, storm throughflow convergence and canopy root strength are achieved. The forest ecosystem adjusts patterns of foliar and root biomass in response to accessible light, water and nutrient resources, which are in turn conditioned by hydroclimate and geomorphically mediated flowpath and transport dynamics. Long term adjustment of drainage network form and density by colluvial and fluvial transport mass budgets provide slowly varying boundary conditions to hillslope hydrologic and geomorphic dynamics. We use a combination of detailed empirical observations and simulation modeling of coupled ecosystem, hydroclimate and geomorphic systems to derive the co-evolution of patterns of forest catchment water, energy and nutrient use efficiency, and the stability and response catchment form to long and short term climate perturbations.

  20. Spatial and temporal occurrence of preferential flow in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Wiekenkamp, I.; Huisman, J. A.; Bogena, H. R.; Lin, H. S.; Vereecken, H.

    2016-03-01

    The highly dynamic nature of preferential flow in time and space makes it challenging to identify and analyze its occurrence at the catchment scale. Novel analysis methods using soil moisture sensor response times offer an opportunity to investigate catchment-wide controls on preferential flow. The aim of this study was to identify factors that control preferential flow occurrence based on 3-year soil moisture monitoring using a wireless sensor network in the Wüstebach catchment, Germany. At 101 locations, the sensor response times at three depths (5, 20, and 50 cm) were classified into one of four classes: (1) non-sequential preferential flow, (2) velocity-based preferential flow, (3) sequential flow, and (4) no response. A conceptual model, postulating that preferential flow in the Wüstebach catchment is dominated by differences in soil type, landscape position, and rainfall input, was proposed for hypothesis testing. To test the conceptual model, the classification results were combined with spatial and event-based data to understand and identify controlling factors. Spatial parameters consisted of hydrological, topographical, and soil physical and chemical parameters. Temporal factors included precipitation characteristics and antecedent soil moisture conditions. The conceptual model as proposed could only be partly confirmed. Event-based occurrence of preferential flow was highly affected by precipitation amount, with a nearly catchment-wide preferential response during large storm events. During intermediate events, preferential flow was controlled by small-scale heterogeneity, instead of showing catchment-wide patterns. The effect of antecedent catchment wetness on the occurrence of preferential flow was generally less profound, although a clear negative relationship was found for precipitation events with more than 25 mm. It was found that spatial occurrence of preferential flow was however governed by small-scale soil and biological features and local

  1. Nitrate Variability in Hydrological Flowpaths for a Mid-Appalachian Forested Catchment Following a Large-Scale Defoliation

    NASA Astrophysics Data System (ADS)

    Riscassi, A. L.; Scanlon, T. M.

    2007-12-01

    Nitrogen (N) leakage from forested watersheds due to disturbance is a well-documented, but not well understood process that contributes to the degradation of receiving waters through eutrophication. Several studies have shown that large scale defoliation events in small forested watersheds in the Eastern U.S. cause immediate and dramatic increases in N flux to streams. Recovery times can differ dramatically depending upon location. Reasons for these differences are not well understood, however, because N transport and transformation processes are difficult to track over these long recovery timescales. This research focuses on a large-scale gypsy moth defoliation event that impacted Shenandoah National Park (SNP) in the late 1980s to early 1990s. Water chemistry and discharge have been monitored at a number of catchments within SNP over the timeframe since the defoliation. Recovery of these systems to pre-defoliation N levels has been observed to be unusually slow, lasting over a decade. Availability of high-frequency (i.e. hourly) stream chemistry and discharge data during storm events throughout the period of recovery allows us to investigate short- and long-term mechanisms for N "leaks" from forested watersheds. Through geochemical hydrograph separation techniques, we can determine how nitrate concentrations vary between event, soil, and groundwater during and in the years following a disturbance. Analyses focus on Paine Run, a 12.4 km2 catchment where over 50 storms have been characterized since the 1990-1992 defoliation. Standard geochemical hydrograph separation is performed using conservative tracers to determine the relative flow contributions from the three flow components for each measurement time step. Computed discharge components, along with measured steam nitrate concentrations (NO3 -) at each time-step, were used to solve for the relative concentration of NO3 - in each of the hydrologic zones for storms by solving the over-determined set of mixing

  2. Surface resistance calibration for a hydrological model using evapotranspiration retrieved from remote sensing data in Nahe catchment forest area

    NASA Astrophysics Data System (ADS)

    Bie, W.; Casper, M. C.; Reiter, P.; Vohland, M.

    2015-05-01

    In this paper, a method combining graphical and statistical techniques is proposed for surface resistance calibration in a distributed hydrological model, WaSiM-ETH, by comparing daily evapotranspiration simulated by model WaSiM-ETH with corresponding daily evapotranspiration retrieved from remote sensing images. The study area locates in Nahe catchment (Rhineland-Palatinate, Germany, 4065 km2) forest regions. The remote sensing based observations are available for a very limited number of days but representative for most soil moisture conditions. By setting canopy resistance (rc) at 150 s/m, soil surface resistance (rse) at 250 s/m or at 300 s/m for deciduous forest and setting rc at 300 s/m, rse at 600 s/m or at 650 s/m for pine forest, the model exhibits its best overall performance in space and time. It is also found that with sufficient soil moisture, the model exhibits its best performance in space scale.

  3. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Quality Specifications for Raw Material § 58.720 Acidifying agents. Acidifying agents if used shall be those permitted by the Food...

  4. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Quality Specifications for Raw Material § 58.720 Acidifying agents. Acidifying agents if used shall be those permitted by the Food...

  5. Hydrologic monitoring in 1-km2 headwater catchments in Sierra Nevada forests for predictive modeling of hydrologic response to forest treatments across 140-km2 firesheds

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Bales, R. C.; Conklin, M. H.; Martin, S. E.; Rice, R.

    2010-12-01

    As part of the Sierra Nevada Adaptive Management Project, an eight-year study designed to measure the impacts of forest treatments (thinning, mastication, controlled burns) on multiple forest attributes, four headwater catchments were established to provide data on hydrologic response to treatments. These 1-km2 study catchments are each sited within 40-100 km2 firesheds, which in this case largely follow watershed boundaries, and which are the larger study areas for informing adaptive management of approximately 3,000 km2 of mixed-conifer forest in California’s central and southern Sierra Nevada. The aim of the hydrologic design was to put in place a ground-based monitoring network that would measure hydrologic attributes at representative locations, and when combined with remotely sensed data, provide a basis for predictive modeling of the larger study area. The selected locations employ instrument clusters, or groupings of instruments in a compact arrangement, to maximize the number of measurements possible and accessibility to the monitoring sites. The two study firesheds , located in the Tahoe and Sierra National Forests, cover a total of about 140-km2. Within each fireshed, two meteorological stations were placed near 1650-m and 2150-m, spanning the precipitation gradient from lower-elevation rain-dominated to higher-elevation snow-dominated systems. Two headwater streams draining approximately 1-km2 are monitored for stage, discharge, electrical conductivity, and sediment movement. Additionally, instrument nodes to monitor temperature, snow depth and soil moisture are installed within 0.5-1 km of the outlet and meterological stations. These nodes were placed to monitor end members of aspect, slope, elevation and canopy cover, which set the boundaries for the model outputs. High-resolution LiDAR provides the topographic and distributed vegetation characteristics, which are combined with field surveys and standard soils information to define the modeling

  6. The role of the forest cover on the definition of runoff coefficient in a regional flood frequency analysis applied to Mediterranean catchments

    NASA Astrophysics Data System (ADS)

    Battista Chirico, Giovanni; Forzieri, Giovanni; Preti, Federico

    2014-05-01

    Flood frequency is fundamental for planning and design structural and non-structural mitigation strategies against land degradation. Flood frequency analysis aims at estimating the probability distributions of flood peaks, so that the flood magnitude for any design return period can be easily determined. The approach commonly employed in engineering hydrology in ungauged catchments is the regional analysis, which exploits the hydrological similarities among catchments and the scaling properties of flood statistics for exporting the information available in gauged catchments to ungauged catchments. One of method most widely applied by hydrologists and engineers is the index flood method, based on the identification of homogeneous regions, where the probability distributions of the annual maximum floods are assumed invariant except for a site-specific scale parameter known as the index flood. The index flood is generally assumed coincident with the mean of annual maximum of flood peaks and is estimated by indirect methods. An indirect estimation method largely applied is based on a conceptual model structured according to the well-known rational formula. A key parameter of the rational formula is the runoff coefficient, which can be interpreted as a probabilistic factor controlling not only the position but also the slope and the curvature of the flood frequency curve. Provided that vegetation patterns can have a significant influence on the catchment antecedent conditions as well as on other rainfall runoff processes in rural catchments, in this study we explore to what extent forest cover can be employed to predict the runoff coefficient, in the framework of a regional flood frequency analysis based on the rational formula coupled with a regional analysis of annual maximum rainfall depths. The results of a k-means cluster analysis applied to a data set of 75 catchments distributed from South to Central Italy, evidenced that the second component of the runoff

  7. Processes affecting oxygen isotope ratios of atmospheric and ecosystem sulfate in two contrasting forest catchments in Central Europe

    SciTech Connect

    Martin Novak; Myron J. Mitchell; Iva Jackova; Frantisek Buzek; Jana Schweigstillova; Lucie Erbanova; Richard Prikryl; Daniela Fottova

    2007-02-15

    Sulfate aerosols are harmful as respirable particles. They also play a role as cloud condensation nuclei and have radiative effects on global climate. A combination of {delta}{sup 18}O-SO{sub 4} data with catchment sulfur mass balances was used to constrain processes affecting S cycling in the atmosphere and spruce forests of the Czech Republic. Extremely high S fluxes via spruce throughfall and runoff were measured at Jezeri (49 and 80 kg S ha{sup -1} yr{sup -1}, respectively). The second catchment, Na Lizu, was 10 times less polluted. In both catchments, {delta}{sup 18}O-SO{sub 4} decreased in the following order: open-area precipitation {gt} throughfall {gt} runoff. The 180-SO{sub 4} values of throughfall exhibited a seasonal pattern at both sites, with maxima in summer and minima in winter. This seasonal pattern paralleled {delta}{sup 18}O-H{sub 2}O values, which were offset by -18{per_thousand}. Sulfate in throughfall was predominantly formed by heterogeneous (aqueous) oxidation of SO{sub 2}. Wet-deposited sulfate in an open area did not show systematic {delta}{sup 18}O-SO{sub 4} trends, suggesting formation by homogeneous (gaseous) oxidation and/or transport from large distances. The percentage of incoming S that is organically cycled in soil was similar under the high and the low pollution. High-temperature {sup 18}O-rich sulfate was not detected, which contrasts with North American industrial sites. 29 refs., 4 figs., 3 tabs.

  8. Integration of Volterra model with artificial neural networks for rainfall-runoff simulation in forested catchment of northern Iran

    NASA Astrophysics Data System (ADS)

    Kashani, Mahsa H.; Ghorbani, Mohammad Ali; Dinpashoh, Yagob; Shahmorad, Sedaghat

    2016-09-01

    Rainfall-runoff simulation is an important task in water resources management. In this study, an integrated Volterra model with artificial neural networks (IVANN) was presented to simulate the rainfall-runoff process. The proposed integrated model includes the semi-distributed forms of the Volterra and ANN models which can explore spatial variation in rainfall-runoff process without requiring physical characteristic parameters of the catchments, while taking advantage of the potential of Volterra and ANNs models in nonlinear mapping. The IVANN model was developed using hourly rainfall and runoff data pertaining to thirteen storms to study short-term responses of a forest catchment in northern Iran; and its performance was compared with that of semi-distributed integrated ANN (IANN) model and lumped Volterra model. The Volterra model was applied as a nonlinear model (second-order Volterra (SOV) model) and solved using the ordinary least square (OLS) method. The models performance were evaluated and compared using five performance criteria namely coefficient of efficiency, root mean square error, error of total volume, relative error of peak discharge and error of time for peak to arrive. Results showed that the IVANN model performs well than the other semi-distributed and lumped models to simulate the rainfall-runoff process. Comparing to the integrated models, the lumped SOV model has lower precision to simulate the rainfall-runoff process.

  9. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Acidified milk. 131.111 Section 131.111 Food and... CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.111 Acidified milk. (a) Description. Acidified milk is the food produced by souring one or more of the optional dairy...

  10. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Acidified milk. 131.111 Section 131.111 Food and... CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.111 Acidified milk. (a) Description. Acidified milk is the food produced by souring one or more of the optional dairy...

  11. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Acidified milk. 131.111 Section 131.111 Food and... CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.111 Acidified milk. (a) Description. Acidified milk is the food produced by souring one or more of the optional dairy...

  12. Shallow subsurface storm flow in a forested headwater catchment: Observations and modeling using a modified TOPMODEL

    NASA Astrophysics Data System (ADS)

    Scanlon, Todd M.; Raffensperger, Jeff P.; Hornberger, George M.; Clapp, Roger B.

    2000-09-01

    Transient, perched water tables in the shallow subsurface are observed at the South Fork Brokenback Run catchment in Shenandoah National Park, Virginia. Crest piezometers installed along a hillslope transect show that the development of saturated conditions in the upper 1.5 m of the subsurface is controlled by total precipitation and antecedent conditions, not precipitation intensity, although soil heterogeneities strongly influence local response. The macroporous subsurface storm flow zone provides a hydrological pathway for rapid runoff generation apart from the underlying groundwater zone, a conceptualization supported by the two-storage system exhibited by hydrograph recession analysis. A modified version of TOPMODEL is used to simulate the observed catchment dynamics. In this model, generalized topographic index theory is applied to the subsurface storm flow zone to account for logarithmic storm flow recessions, indicative of linearly decreasing transmissivity with depth. Vertical drainage to the groundwater zone is required, and both subsurface reservoirs are considered to contribute to surface saturation.

  13. Shallow subsurface storm flow in a forested headwater catchment: Observations and modeling using a modified TOPMODEL

    USGS Publications Warehouse

    Scanlon, T.M.; Raffensperger, J.P.; Hornberger, G.M.; Clapp, R.B.

    2000-01-01

    Transient, perched water tables in the shallow subsurface are observed at the South Fork Brokenback Run catchment in Shenandoah National Park, Virginia. Crest piezometers installed along a hillslope transect show that the development of saturated conditions in the upper 1.5 m of the subsurface is controlled by total precipitation and antecedent conditions, not precipitation intensity, although soil heterogeneities strongly influence local response. The macroporous subsurface storm flow zone provides a hydrological pathway for rapid runoff generation apart from the underlying groundwater zone, a conceptualization supported by the two-storage system exhibited by hydrograph recession analysis. A modified version of TOPMODEL is used to simulate the observed catchment dynamics. In this model, generalized topographic index theory is applied to the subsurface storm flow zone to account for logarithmic storm flow recessions, indicative of linearly decreasing transmissivity with depth. Vertical drainage to the groundwater zone is required, and both subsurface reservoirs are considered to contribute to surface saturation.

  14. Determining Solute Sources and Water Flowpaths in a Forested Headwater Catchment: Advances With the Ca-Sr-Ba Multi-tracer

    NASA Astrophysics Data System (ADS)

    Bullen, T. D.; Bailey, S. W.; McGuire, K. J.; Zimmer, M. A.; Ross, D. S.

    2011-12-01

    Determining solute sources and water flowpaths in catchments is of critical importance to development of models that effectively describe catchment function. For solutes in soil water and stream water, simple mass balance models that compare precipitation input to catchment outlet compositions can predict average mineral weathering contributions for the catchment as a whole, but fail to provide information about either variability of contributions from different portions of the catchment and different soil depths or processes such as ion exchange and biological cycling. In order to better understand how forested headwater catchments function, we are interpreting concentration and isotope ratios of the alkaline earth elements Ca, Sr and Ba in streamwater, groundwater, the soil ion exchange pool and plants in a hydropedologic context at the 41 hectare hydrologic reference catchment (Watershed 3) at the Hubbard Brook Experimental Forest, New Hampshire, USA. This forested headwater catchment consists of a beech-birch-maple-spruce forest growing on vertically- and laterally-developed Spodosols and Inceptisols formed on granitoid glacial till that mantles Paleozoic metamorphic bedrock. Across the watershed in terms of the soil ion exchange pool, the forest floor has high Sr/Ba and Ca/Sr ratios, mineral soils have intermediate Sr/Ba and low Ca/Sr, and relatively unweathered till in the C horizon has low Sr/Ba and high Ca/Sr. Waters moving through these various compartments will obtain Sr/Ba and Ca/Sr ratios reflecting these characteristics, and thus variations of Sr/Ba and Ca/Sr of streamwater provide evidence of the depth of water flowpaths feeding the streams. 87Sr/86Sr of exchangeable Sr spans a broad range from 0.715 to 0.725, with highest values along the mid-to upper flanks of the catchment and lowest values in a broad zone along the central axis of the catchment associated with numerous groundwater seeps. Thus, variations of 87Sr/86Sr in streamwater provide

  15. Impacts of forest thinning and climate change on transpiration and runoff rates in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Ray, R. L.; Bales, R. C.; Conklin, M. H.

    2013-12-01

    Using a spatially explicit hydro-ecological model, impacts from forest thinning and climate change on snowpack, evapotranspiration (ET) rates, soil moisture storage, and runoff were investigated in Sierra Nevada headwater catchments spanning elevations of 1,500 to 2,000-m. Along this elevation gradient, precipitation changes from rain-dominated to snow-dominated, so precipitation phase will be strongly impacted by increases in temperature. Mixed-conifer forests in the Sierra Nevada near the 2,000-m elevation band also transpire at a high rate relative to upper elevation forests that are more restricted by colder winter temperatures and lower elevation forests that are more restricted by lower summer soil moisture, increasing the potential of reduced transpiration with vegetation thinning. Forest treatment and climate change scenarios were modeled using the Regional Hydro-Ecological Simulation System (RHESSys), calibrated with two years of snow, soil moisture, and streamflow observations. Simulations of forest thinning at moderate (66% of current vegetation density) and restoration (33% density) levels were combined with precipitation changes up to 20% and temperature increases up to 6οC for projecting impacts on ET and runoff rates. Model results indicated that moderate thinning alone could increase runoff by 3%, but additional temperature increases of 2-4οC could increase runoff rates another 6% - similar to a restoration level thinning. Modifying temperature and precipitation separately showed that the two methods of climate forcing both led to fluctuations in soil moisture, caused by changes in precipitation phase (snow/rain) and final day of snowpack melt. The snowmelt timing affected runoff rates by causing changes in the spring soil moisture recession, and showed that it may be one of the critical processes that affects annual runoff rates, not just runoff timing. Simulations of precipitation and temperature changes together showed that precipitation would

  16. Interpretation of concentration-discharge patterns in acid-neutralizing capacity during storm flow in three small, forested catchments in Shenandoah National Park, Virginia

    USGS Publications Warehouse

    Rice, K.C.; Chanat, J.G.; Hornberger, G.M.; Webb, J.R.

    2004-01-01

    Episodic concentration-discharge (c-Q) plots are a popular tool for interpreting the hydrochemical response of small, forested catchments. Application of the method involves assuming an underlying conceptual model of runoff processes and comparing observed c-Q looping patterns with those predicted by the model. We analyzed and interpreted c-Q plots of acid-neutralizing capacity (ANC) for 133 storms collected over a 7-year period from three catchments in Shenandoah National Park, Virginia. Because of their underlying lithologies the catchments represent a gradient in both hydrologic and geochemical behavior, ranging from a flashy, acidic, poorly buffered catchment to a moderate, neutral, well-buffered catchment. The relative frequency of observed anticlockwise c-Q loops in each catchment decreased along this gradient. Discriminant function analysis indicated that prestorm base flow ANC was an important predictor of loop rotation direction; however, the strength of the predictive relationship decreased along the same gradient. The trends were consistent with several equally plausible three-component mixing models. Uncertainty regarding end-member timing and relative volume and possible time variation in end-member concentrations were key factors precluding identification of a unique model. The inconclusive results obtained on this large data set suggest that identification of underlying runoff mechanisms on the basis of a small number of c-Q plots without additional supporting evidence is likely to be misleading.

  17. Flow simulation and erosion assessment in a ditch network of a drained peatland forest catchment in Eastern Finland

    NASA Astrophysics Data System (ADS)

    Haahti, Kersti; Koivusalo, Harri; Younis, Bassam; Stenberg, Leena

    2014-05-01

    One third of the land area in Finland is covered by peatlands and today 4.5 million ha of peatlands are drained for forestry purposes. In order to sustain forest productivity, ditch networks are maintained annually on an area of approximately 60 000 ha. The suspended solid (SS) load from drained peatland forest sites after ditch network maintenance causes one of the largest strains on the water system by forestry in Finland. Understanding the hydraulic processes in newly maintained ditch networks is necessary for quantifying the SS load generation and transport in the source areas. In this study we developed a hydraulic unsteady-flow model to predict the behavior of flow in a drainage network in a boreal forested peatland site. The input to this model was in the form of a discharge hydrograph that was produced by a hydrological model (FEMMA). The simulations were performed using the algorithm of Zhu et al. (2011) for unsteady flows in a network of channels. In this iterative procedure, the Saint-Venant equations that govern the flow in each of the network channels were solved separately, and the flow depths at the junction-points were corrected using the method of characteristics. The algorithm was programmed using the numeric computing environment MATLAB by MathWorks. Based on the hydraulic conditions produced by the model, erosion risk within the network was evaluated. The model was applied to a peatland catchment drained for forestry in Koivupuro in Eastern Finland (63°53' N, 28°40' E). In August 2011, most of the Koivupuro catchment ditch network was maintained creating simultaneously a smaller nested catchment (area 5.2 ha) which was the focus of this study. The ditch network consisted of 15 branches, altogether 1.6 km in length, and 8 junctions. The model performance was evaluated against flow depth measurements at 5 locations in the network. The simulations in the small ditches of Koivupuro with mostly very low flow rate (< 0.05 m3/s) introduced its

  18. Using (137)Cs and (210)Pbex and other sediment source fingerprints to document suspended sediment sources in small forested catchments in south-central Chile.

    PubMed

    Schuller, P; Walling, D E; Iroumé, A; Quilodrán, C; Castillo, A; Navas, A

    2013-10-01

    A study of the impact of forest harvesting operations on sediment mobilization from forested catchments has been undertaken in south-central Chile. The study focused on two sets of small paired catchments (treatment and control), with similar soil type, but contrasting mean annual rainfall, located about 400 km apart at Nacimiento (1200 mm yr(-1)) and Los Ulmos (2500 mm yr(-1)). The objective was to study the changes in the relative contribution of the primary sources of fine sediment caused by forestry operations. Attention focused on the pre-harvest and post-harvest periods and the post-replanting period was included for the Nacimiento treatment catchment. The sediment source fingerprinting technique was used to document the contributions of the potential sources. Emphasis was placed on discriminating between the forest slopes, forest roads and channel erosion as potential sources of fine sediment and on assessing the relative contributions of these three sources to the sediment yield from the catchments. The fallout radionuclides (FRNs) (137)Cs and excess lead-210, the environmental radionuclides (226)Ra and (40)K and soil organic matter (SOM) were tested as possible fingerprints for discriminating between potential sediment sources. The Kruskal-Wallis test and discriminant function analysis were used to guide the selection of the optimum fingerprint set for each catchment and observation period. Either one or both of the FRNs were selected for inclusion in the optimum fingerprint for all datasets. The relative contribution of each sediment source to the target sediment load was estimated using the selected fingerprint properties, and a mixing model coupled with a Monte Carlo simulation technique that takes account of uncertainty in characterizing sediment source properties. The goodness of fit of the mixing model was tested by comparing the measured and simulated fingerprint properties for the target sediment samples. In the Nacimiento treatment catchment

  19. Tracing Nitrogen Sources in Forested Catchments Under Varying Flow Conditions: Seasonal and Event Scale Patterns

    NASA Astrophysics Data System (ADS)

    Sebestyen, S. D.; Shanley, J. B.; Boyer, E. W.; Kendall, C.

    2004-12-01

    Our ability to assess how stream nutrient concentrations respond to biogeochemical transformations and stream flow dynamics is often limited by datasets that do not include all flow conditions that occur over event, monthly, seasonal, and yearly time scales. At the Sleepers River Research Watershed in northeastern Vermont, USA, nitrate, DOC (dissolved organic carbon), and major ion concentrations were measured on samples collected over a wide range of flow conditions from summer 2002 through summer 2004. Nutrient flushing occurred at the W-9 catchment and high-frequency sampling revealed critical insights into seasonal and event-scale controls on nutrient concentrations. In this seasonally snow-covered catchment, the earliest stage of snowmelt introduced nitrogen directly to the stream from the snowpack. As snowmelt progressed, the source of stream nitrate shifted to flushing of soil nitrate along shallow subsurface flow paths. In the growing season, nitrogen flushing to streams varied with antecedent moisture conditions. More nitrogen was available to flush to streams when antecedent moisture was lowest, and mobile nitrogen stores in the landscape regenerated under baseflow conditions on times scales as short as 7 days. Leaf fall was another critical time when coupled hydrological and biogeochemical processes controlled nutrient fluxes. With the input of labile organic carbon from freshly decomposing leaves, nitrate concentrations declined sharply in response to in-stream immobilization or denitrification. These high-resolution hydrochemical data from multiple flow regimes are identifying "hot spots" and "hot moments" of biogeochemical and hydrological processes that control nutrient fluxes in streams.

  20. Observations and modeling of hillslope throughflow temperatures in a coastal forested catchment

    NASA Astrophysics Data System (ADS)

    Leach, J. A.; Moore, R. D.

    2015-05-01

    A growing body of research on stream thermal regimes has highlighted the importance of heat advection associated with surface water and groundwater interactions, such as hyporheic exchange, groundwater discharge, and hillslope throughflow inputs. Existing catchment models that predict stream temperature use a variety of approaches to estimate throughflow temperatures, but none has been evaluated against field measurements of throughflow temperature. In this study, throughflow temperatures were monitored over two winters at 50 locations adjacent to a headwater stream (11 ha catchment area) located in the rain-on-snow zone of the Pacific Northwest. Existing approaches to estimate throughflow temperature under or overpredicted throughflow temperatures by up to 5°C, or were unable to represent the influence of transient snow cover. Therefore, a conceptual-parametric model that is computationally efficient was developed that simulates hillslope hydrology and throughflow temperatures. The model structure includes an upslope reservoir that drains into a downslope reservoir that, in turn, drains into the stream. Vertical and lateral energy and water fluxes are simulated using simplified process representations. The model successfully predicts throughflow temperatures and highlights the dominant role of throughflow advection and the influence of snow cover on stream thermal regimes during high flow periods and rain-on-snow events.

  1. Analysis of runoff sources and water uptake by trees using isotopic data in a small forested catchment

    NASA Astrophysics Data System (ADS)

    Mantese, N.; Penna, D.; Zuecco, G.; Borga, M.; Anfodillo, T.; Carraro, V.; Dalla Fontana, G.

    2012-04-01

    Plant transpiration is an important component of the hydrological cycle. Particularly, in densely vegetated areas, climatic and land-use changes might have significant hydrological (and ecological) implications. This leads to the need to identify the main water sources for tree transpiration and to evaluate how the flux exchanges between soil, vegetation and atmosphere possibly affect the runoff response of forested watersheds. Specifically, this study took advantage of the natural presence of water stable isotopes in the hydrological cycle to assess: i) the sources of water uptake by trees, and ii) the origin of water contributing to runoff in a small and densely forested catchment in the Italian Pre-Alps. Field surveys were carried out during late summer and early autumn of 2011 in the Ressi catchment (1.9 ha, North-Eastern Italy, mean elevation of 660 m a.s.l.). Beeches, chestnuts, maples and hazels represent the main tree species in the area, with sparse presence of hornbeams and ashes. Stream water stage, soil moisture at 0-30 cm depth at four locations, and water table level at three locations were continuously recorded. Bulk precipitation was collected from plastic bottles sealed with mineral oil and weekly manual sampling of stream water, soil water (by means of suction cups), groundwater and water in the xylem conduits (sap) from six beeches was performed for isotopic analyses. Sap was extracted in situ from beech twigs by using a pressure bomb. The isotopic composition of liquid samples (δ2H and δ18O) was determined by laser absorption spectroscopy. Additionally, water electrical conductivity was measured in the field (only for stream water, groundwater and rainfall) by a portable conductivity meter. Preliminary results showed a marked difference in the tracer concentration among the various water components in the catchment. Particularly, the average isotopic signal of tree water (-38.1 per mil δ2H and -5.95 δ18O) was statistically similar to soil

  2. Spatial distributions of forest stand condition, vegetation ground cover, and soil erosion for evaluating the linkages of sediment transport from hillslopes to streams in headwater catchments

    NASA Astrophysics Data System (ADS)

    Gomi, T.; Kumakura, A.; Mizugaki, S.; Takahisa, F.; Ishikawa, Y.; Uchiyama, Y.

    2011-12-01

    We investigated soil erosion and resultant fine sediment transport in headwater catchments with heterogeneous spatial patterns of forest stand condition and vegetation ground cover. The study was conducted in 7 and 5 ha headwater catchments (Watersheds No.3 and No.4, respectively) in Tanzawa mountains area, 60 km of southwest of Tokyo, Japan. We selected 53 points located within catchments including near stream channels to the ridge line. A 0.5 x 0.5 m plot (1m x 1m) were selected in each point for investigating vegetation biomass, litter cover, soil erosion (e.g., soil pedestal), overstory vegetation condition (type of forest and canopy openness), and soil physical properties (e.g., soil bulk density and particle size). We assumed that high of soil pedestal indicated short term soil erosions by soil splash and related down slope soil movement. Percentages of bare soil in No. 3 tend to greater than ones in No.4. In addition, bare soil slope tended to distributed lower part of hillslopes with > 45° in gradient, where the soil can be transported to streams. Because of the high soil erosion rate in No.3 catchment, suspended sediment and bedload transport in No.3 tended to be greater ones in No.4 catchment. Fingerprinting approach using activities of fallout radionuclides (caesium-137 and excess lead-210) confirmed that some of the fine sediment transport at associated with hillslope soil surface erosion. Findings of this study suggested that processes of catchment scale fine sediment depending on the linkages between hillslope and channels.

  3. Community structures and activity of denitrifying microbes in a forested catchment in central Japan: survey using nitrite reductase genes

    NASA Astrophysics Data System (ADS)

    Ohte, N.; Aoki, M.; Katsuyama, C.; Suwa, Y.; Tange, T.

    2012-12-01

    To elucidate the mechanisms of denitrification processes in the forested catchment, microbial ecological approaches have been applied in an experimental watershed that has previously investigated its hydrological processes. The study catchment is located in the Chiba prefecture in central Japan under the temperate Asian monsoon climate. Potential activities of denitrification of soil samples were measured by incubation experiments under anoxic condition associated with Na15NO3 addition. Existence and variety of microbes having nitrite reductase genes were investigated by PCR amplification, cloning and sequencings of nirK and nirS fragments after DNA extraction. Contrary to our early expectation that the potential denitrification activity was higher at deeper soil horizon with consistent groundwater residence than that in the surface soil, denitrification potential was higher in shallower soil horizons than deeper soils. This suggested that the deficiency of NO3- as a respiratory substrate for denitrifier occurred in deeper soils especially in the summer. However, high denitrification activity and presence of microbes having nirK and nirS in surface soils usually under aerobic condition was explainable by the fact that the majority of denitrifying bacteria have been recognized as a facultative anaerobic bacterium. This also suggests the possibility of that denitrification occurs even in the surface soils if the wet condition is provided by rainwater during and after a storm event. Community structures of microbes having nirK were different between near surface and deeper soil horizons, and ones having nirS was different between saturated zone (under groundwater table) and unsaturated soil horizons. These imply that microbial communities with nisK are sensitive to the concentration of soil organic matters and ones with nirS is sensitive to soil moisture contents.

  4. Hydrological and erosion response at micro-plot to -catchment scale following forest wildfire, north-central Portugal

    NASA Astrophysics Data System (ADS)

    Vieira, Diana; Keizer, Jan Jacob; Nunes, João. Pedro; Fernandes, Isabel; Ferreira, Raquel; Pereira, Luísa; Prats, Sergio; Ermitas Rial, María.; Eufemia Varela, María.

    2010-05-01

    Wildfires can have important impacts on hydrological and soil erosion processes, due to the destruction of vegetation cover and changes to soil properties. According to Shakesby and Doerr (2006), these wildfire effects are: i) much better known at small spatial scales (especially erosion plots) than at the scale of catchments; ii) much better studied with respect to overland flow and streamflow (and, then, especially peak discharges) than to soil erosion. Following up on a precursor project studying runoff generation and the associated soil losses from micro-plot to slope-scale in Portuguese eucalypt forests, the EROSFIRE-II project addresses the connectivity of these processes across hillslopes as well as within the channel network. This is done in the Colmeal study area in central Portugal, where the outlet of an entirely burnt catchment of roughly 10 ha was instrumented with a gauging station continuously recording water level and tubidity, and five slopes were each equipped with 4 runoff plots of < 0,5 m2 ("micro-plot") and 4 slope-scale plots as well as 1 slope-scale sediment fence. Starting one month after the August 2008 wildfire, the plots were monitored at 1- to 2-weekly intervals, depending on the occurrence of rainfall. The gauging station became operational at the end of November 2008, since the in-situ construction of an H-flume required several weeks. A preliminary analysis of the data collected till the end of 2008, focusing on two slopes with contrasting slope lengths as well as the gauging station: revealed clear differences in runoff and erosion between: (i) the micro-plot and slope-scale plots on the same hillslope; (ii) the two slopes; (iii) an initial dry period and a subsequent much wetter period; (iv) the slopes and the catchment-scale, also depending on the sampling period. These results suggest that the different processes govern the hydrological and erosion response at different spatial scales as well as for different periods, with soil

  5. Searching for Similarity in Catchment Controls on Complex C, N, and P Export Patterns from Forests to Surface Waters across Continental Scale Gradients (Invited)

    NASA Astrophysics Data System (ADS)

    Creed, I. F.

    2010-12-01

    Inter-catchment comparison of solute export from terrestrial to aquatic ecosystems is challenging due in part to natural sources of variation caused by topographic controls on processes that affect solute movement. Recent advances in digital elevation models (DEMs) enable more precise characterization of the topographic features that define source areas of carbon (C), nitrogen (N), and phosphorus (P) as well as the movement of these elements to the sink areas where they are stored, converted to gaseous forms, and/or exported to aquatic systems. This is particularly true in catchments with dense forest canopies that conceal these topographic features from aerial views. A conceptual model developed from a forested catchment in central Ontario, Canada presented here details the topographically controlled processes regulating source areas of solutes, their movement, and their fate. Statistical models relating topographic attributes representing these processes using digital terrain analysis on a 5 x 5 m LiDAR DEM explained the majority of the natural sources of variation in solute exports for forested catchments within the geographic region. Topographic attributes representing hydrologic flushing areas and the potential rate of expansion of these flushing areas were important in controlling nitrate-N export (explaining 85% of the natural variation in export). In contrast, hydrologically saturated areas that were contiguous and connected to the stream were important in controlling dissolved organic nutrient export (65% dissolved organic N, 90% dissolved organic C, and 87% total dissolved phosphorus). Based on the success from this geographic region, the topographic attributes were applied to forested catchments along an E-W gradient across eastern Canada (from dry to wet climatic conditions, with shallow soils) and along a N-S gradient along eastern North America (from snow to snow-free seasons, with shallow to deep soils), and across forest regions ranging from

  6. Climate response of the soil nitrogen cycle in three forest types of a headwater Mediterranean catchment

    NASA Astrophysics Data System (ADS)

    Lupon, Anna; Gerber, Stefan; Sabater, Francesc; Bernal, Susana

    2015-05-01

    Future changes in climate may affect soil nitrogen (N) transformations, and consequently, plant nutrition and N losses from terrestrial to stream ecosystems. We investigated the response of soil N cycling to changes in soil moisture, soil temperature, and precipitation across three Mediterranean forest types (evergreen oak, beech, and riparian) by fusing a simple process-based model (which included climate modifiers for key soil N processes) with measurements of soil organic N content, mineralization, nitrification, and concentration of ammonium and nitrate. The model describes sources (atmospheric deposition and net N mineralization) and sinks (plant uptake and hydrological losses) of inorganic N from and to the 0-10 cm soil pool as well as net nitrification. For the three forest types, the model successfully recreated the magnitude and temporal pattern of soil N processes and N concentrations (Nash-Sutcliffe coefficient = 0.49-0.96). Changes in soil water availability drove net N mineralization and net nitrification at the oak and beech forests, while temperature and precipitation were the strongest climatic factors for riparian soil N processes. In most cases, net N mineralization and net nitrification showed a different sensitivity to climatic drivers (temperature, soil moisture, and precipitation). Our model suggests that future climate change may have a minimal effect on the soil N cycle of these forests (<10% change in mean annual rates) because positive warming and negative drying effects on the soil N cycle may counterbalance each other.

  7. Erosion process contribution to sediment yield before and after the establishment of exotic forest: Waipaoa catchment, New Zealand

    NASA Astrophysics Data System (ADS)

    Marden, M.; Herzig, A.; Basher, L.

    2014-12-01

    The East Coast region of the North Island, New Zealand, is well known for its severe erosion, high sediment yields, flooding, and sedimentation following extensive deforestation of its indigenous forest during the late 19th and early 20th centuries. For six decades thereafter, extensive grazing (cattle and sheep) left a legacy of highly degraded hill country, much of which has since been retired and planted in exotic forest, primarily to control erosion. Previous studies have documented the extent of gully erosion, calculated erosion rates and sediment delivery from gullies to the channel load within the study basin, but this has not been quantified for the more extensive mass movement processes including slump, earthflow, and shallow landslides. Additionally, the magnitude of the effect of reforestation on sediment load at subcatchment level and, ultimately on sediment yield at catchment scale, for this combination of erosion processes and, over the time frame of a rotation of exotic forest (~ 28 years), is unknown. For a 140-km2 study basin located in the headwaters of the 2150 km2 Waipaoa River catchment, we establish the contribution to basin sediment load by each of these erosion processes, spanning a ~ 50-year period that includes a ~ 28-year reforestation effort. We quantified the effectiveness of exotic reforestation as an erosion control strategy by using the mapped extent of each of the erosion processes before planting (i.e. 1939-59), as the benchmark against which any subsequent change in eroded area (km2) was measured. Based on this, process-based erosion load was calculated for the pre-planting period (1939-59), for the period 10 years after planting commenced (1960-69), and again for the period 1970-88, which marked the completion of planting within the study basin. The study basin sediment load is then expressed as a proportion (percentage) of the measured sediment yield (Mt y- 1) of the wider Waipaoa River catchment. The net area affected by

  8. Investigating the applicability of end-member mixing analysis (EMMA) across scale: A study of eight small, nested catchments in a temperate forested watershed

    NASA Astrophysics Data System (ADS)

    James, April L.; Roulet, Nigel T.

    2006-08-01

    Current interest in multicatchment hydrologic studies challenges the use of geochemical mixing models across scale, where changes in stream water chemistry from catchment to catchment may indicate (1) changes in the proportional contributions of end-members, (2) changes in the geochemical signatures of end-members in space, or (3) changes in the geochemical signatures of end-members in time. In this study we examine stream water chemistry from a series of eight nested catchments in a 1.47 km2 temperate forest watershed in southern Quebec for evidence of contributing end-members. We use eigenvector and residual analysis (Hooper, 2003) of the multivariate stream water chemistry records to estimate the dimensionality of the mixing space for each individual catchment, indicating the number of contributing end-members. Using the mixing space of the largest, highest-order catchment (1.47 km2), we evaluate its ability to predict stream water chemistry in the seven upstream catchments, representing progressively smaller areas. We observe significant spatial variation in ionic mixing ratios within the 147 ha watershed. Only spatial testing across catchments allowed us to identify appropriate conservative tracers most compatible with the application of a single mixing model across scale. On the seasonal timescale, groundwater geochemistry changes significantly due to the recharge from spring snowmelt, indicating a mixture of two groundwater end-members of varying age. On the timescale of storm events, shallow perched water and throughfall provide geochemical signatures consistent with physical mixing while unsaturated zone soil water sampled from local pockets of glacial till does not. Our results suggest cautious application of end-member mixing analysis (EMMA) for multicatchment studies.

  9. Transplanted aquatic mosses for monitoring trace metal mobilization in acidified streams of the Vosges Mountains, France

    SciTech Connect

    Mersch, J.; Guerold, F.; Rousselle, P.; Pihan, J.C. )

    1993-08-01

    As a result of acid depositions, trace metals are mobilized from the soils to the aquatic environment. Especially in poorly mineralized waters, elevated metal concentrations may rapidly have adverse effects on aquatic organisms. In particular, it has been shown that aluminium, a key element in the acidification process, is a toxic cofactor for fish and other biota. An accurate assessment of this specific form of water pollution may not be possible when only based on analyses of single water samples. On the one hand, water metal concentrations are often close to the detection limit of usual analytical techniques, and on the other hand, levels in acidified streams undergo strong temporal variations caused by acid pulses following meteorological events such as heavy rainfall and snowmelt. Compared to water analyses, indirect monitoring methods provide undeniable advantages for assessing water contamination. Aquatic bryophytes, in particular, have been regarded as interesting indicator organisms for trace metal pollution. However, their use has mainly been restricted to the lower course of streams for evaluating the impact of industrial discharges. The purpose of this study was to test the suitability of transplanted aquatic mosses for monitoring aluminium and four other trace metals (copper, iron, lead and zinc) in the particular context of acidifed streams draining a forested headwater catchment. 15 refs., 2 figs., 2 tabs.

  10. Modelling the fate of hydrophobic organic contaminants in a boreal forest catchment: a cross disciplinary approach to assessing diffuse pollution to surface waters.

    PubMed

    Bergknut, Magnus; Meijer, Sandra; Halsall, Crispin; Agren, Anneli; Laudon, Hjalmar; Köhler, Stephan; Jones, Kevin C; Tysklind, Mats; Wiberg, Karin

    2010-09-01

    The fate of hydrophobic organic compounds (HOCs) in soils and waters in a northern boreal catchment was explored through the development of a chemical fate model in a well-characterised catchment system dominated by two land types: forest and mire. Input was based solely on atmospheric deposition, dominated by accumulation in the winter snowpack. Release from soils was governed by the HOC concentration in soil, the soil organic carbon fraction and soil-water DOC content. The modelled export of selected HOCs in surface waters ranged between 11 and 250 ng day(-1) during the snow covered period, compared to 200 and 9600 ng/d during snow-melt; highlighting the importance of the snow pack as a source of these chemicals. The predicted levels of HOCs in surface water were in reasonable agreement to a limited set of measured values, although the model tended to over predict concentrations of HOCs for the forested sub-catchment, by over an order of magnitude in the case of hexachlorobenzene and PCB 180. This possibly reflects both the heterogeneity of the forest soils and the complicated and changing hydrology experienced between the different seasons. PMID:20619517

  11. Sulphate leaching from diffuse agricultural and forest sources in a large central European catchment during 1900-2010.

    PubMed

    Kopáček, Jiří; Hejzlar, Josef; Porcal, Petr; Posch, Maximilian

    2014-02-01

    Using dynamic, mass budget, and empirical models, we quantified sulphate-sulphur (SO4-S) leaching from soils in a large central European catchment (upper Vltava river, Czech Republic) over a 110-year period (1900-2010). SO4-S inputs to soils with synthetic fertilisers and atmospheric deposition increased in the 1950s-1980s, then rapidly decreased (~80%), and remained low since the middle 1990s. The proportion of drained agricultural land rapidly increased from 4 to 43% between the 1950s and 1990s; then the draining ability of the system slowly decreased due to its ageing. Sulphate concentrations in the Vltava exhibited similar trends as the external SO4-S inputs, suggesting that they could be explained by changes in atmospheric and fertiliser S inputs. The available data and modelling, however, showed that (i) internal SO4-S sources (mineralization of soil organic S in the drained agricultural land), (ii) a hysteresis in SO4-S leaching from forest soils (a net S retention at the high S inputs and then a net release at the lowered inputs), and (iii) hydrology must be taken into account. An empirical model was then employed, based on parameters representing hydrology (discharge), external SO4-S sources (inputs by synthetic fertilisers and atmospheric deposition), and internal SO4-S sources (mineralization related to soil drainage). The model explained 84% of the observed variability in annual SO4-S concentrations in the Vltava river during 1900-2010 and showed that forest soils were a net sink (105 kg ha(-1)) while agricultural land was a net source (55 kg ha(-1)) of SO4-S during 1960-2010. In the late 1980s, forest soils changed from a sink to a source of S, and the present release of SO4-S accumulated in forest soils thus delays recovery of surface waters from acidification, while S losses from agricultural soils increase the risk of future S deficiency in S-demanding crops. PMID:24176702

  12. Paired tree and soil instrumentation: what can we learn from two instrumented sites across various gradients in a forested catchment

    NASA Astrophysics Data System (ADS)

    Hartsough, P. C.; Roudneva, E.; Malazian, A. I.; Meadows, M. W.; Bales, R. C.; Hopmans, J. W.

    2012-12-01

    Extensive instrumentation both below and above ground across a forested catchment in the Southern Sierra Critical Zone Observatory (SSCZO) within the Kings River Experimental Watershed (KREW) begins to untangle the complex relationship between precipitation, water storage and transpiration as it relates to water availability from deeper sources. The first instrumented site (CZT-1) includes a White Fir (Abies concolor) situated on a flat ridge with access to deep soil moisture. Monitoring and modeling of shallow and deep soil regions confirm that there is significant soil water available from 100-400cm as the tree exhausts water from shallower depths. A root excavation and limited drilling show roots distributed from 30-150cm with limited roots available to access deeper soil water and water stored in the saprolite. At a second instrumented site, CZT-2, a Ponderosa Pine (Pinus ponderosa) was instrumented with a similar suite of sap flow and soil sensors. The CZT-2 site is on a slight slope and is characterized by shallow soils (<90cm) with extensive cobbles and bedrock outcrops with limited access to deeper soil or saprolite water. The second site also sits in the open while the first site is more protected in a closed forest. The two sites show different responses to changes in rain and snow loading from above as well as soil drainage and water depletion from below across a wet to dry transition. They also have different thresholds for transpiration shut down both due to late season water deficit and also during winter periods where air temperatures are high enough to permit photosynthesis. Sap flux and extensive soil water content and water potential measurements around both trees as well as evapotranspiration measurements from a 50m flux tower located adjacent to the two instrumented trees, show little water limitation during wet years and only moderate water limitation during a drought year. Access to deeper water storage pools is confirmed by modeling results

  13. Effects of plantation forest clearfelling on stream temperatures in the Plynlimon experimental catchments, mid-Wales

    NASA Astrophysics Data System (ADS)

    Stott, T.; Marks, S.

    Hourly stream temperatures monitored over 28 months, which spanned a 3 month period of environmentally sensitive plot-scale harvesting of 20 ha. (20%) of the Nant Tanllwyth catchment (0.89 km2) on the south side of the main stream in early 1996, resulted in a 0.58°C (p< 0.001) increase in monthly mean stream temperature. Over the same 28 month experimental period, there was no significant increase in the monthly mean air temperature recorded at a nearby automatic weather station. Monthly mean temperatures are highest in July and August in the year before and the year after the clearfelling, and one of the main effects of the clearfelling was to decrease the difference between the monthly mean stream and air temperatures. Despite the air temperatures being cooler in the post-clearfelling year, the stream temperatures still showed an increase in the summer months. Monthly mean maximum stream temperatures, also highest in July and August in the year before and the year after the clearfelling, showed a marked increase of 7.0°C: in July and 5.3°C in August from the pre- to the post-clearfelling years, while monthly mean minimum air temperatures actually showed a slight decrease for the same months. The likely effects on stream fauna are discussed, as are suggestions for, and likely effects of, buffer strips alongside the streams.

  14. Geochemical investigation of weathering processes in a forested headwater catchment: Mass-balance weathering fluxes

    USGS Publications Warehouse

    Jones, B.F.; Herman, J.S.

    2008-01-01

    Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basic hydrology. O'Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile. ?? 2008 The Mineralogical Society.

  15. Long-term and short-term erosion rates in river catchments of the Rhenish Massif and the Black Forest, Germany

    NASA Astrophysics Data System (ADS)

    Meyer, H.; Hetzel, R.; Strauss, H.

    2007-12-01

    We constrained long-term erosion rates from the concentration of cosmogenic 10Be in stream sediments in order to quantify the Late Quaternary denudation history of mountain ranges in central Europe. Four different catchments in Germany, ranging in size from 8 to 379 km2 were investigated. Two of them, the Aabach and Möhne catchments drain predominantly low-grade Paleozoic metasediments. The other two, the Gutach and Acher catchments in the Black Forest are situated in Late Paleozoic granites. Erosion rates derived from the 10Be concentrations range from 29 to 86 mm/ka in the Rhenish Massif and from 26 to 91 mm/ka in the Black Forest. These spatially-averaged erosion rates integrate over the past 7 to 23 ka. Central to our investigation are questions concerning the relative importance of lithology and catchment relief on long-term erosion rates. Short-term erosion rates for all catchments were quantified by combining the amounts of suspended and dissolved loads in water samples with water discharge data and basin area. By analyzing the stable isotope signatures δ18O of river water and δ13C of dissolved anorganic carbon and by taking into account the precipitation and evaporation we corrected the dissolved load for organic, atmospheric and anthropogenic inputs. The preliminary short-term erosion rates vary between 9 and 33 mm/ka and are only about one third of the erosion rates derived from 10Be. The short-term erosion rates are complemented by erosion rates derived from the volume of sediment stored behind reservoirs of known age. These erosion rates range from 2 to 13 mm/ka and are lower than the erosion rates derived from river loads, as they do not take into account the dissolved load. Furthermore, we focused on dependence of lithology and land use on short-term erosion rates.

  16. Difference of Ecosystem and Hydrological control on Long-term water quality between adjacent subcatchments in a forested catchment in central Japan

    NASA Astrophysics Data System (ADS)

    Katsuyama, M.; Iwasaki, K.; Nagano, R.; Takaki, K.; Tanaka, Y.

    2014-12-01

    We have been monitoring the water quality in the Kiryu Experimental Watershed (KEW; 5.99 ha), Japan, and four subcatchments for more than 20 years. The climate of KEW is warm temperate. The artificially planted Japanese Cypress around 1960 covers whole of the KEW. The geology of KEW is weathered granite. The concentrations of SiO2 and Na, which are mainly supplied from weathering processes, in streamwater were different between the catchments, and the difference was controlled by hydrological conditions in each catchment; in the catchment where shallow groundwater contribution to the streamflow is large, the concentrations were lower. Conversely, in the catchment where deep, bedrock groundwater contribution is large, these concentrations were higher. The K+ concentration which cycles between soil and plants showed clear seasonal variations and the differences between the catchments were small. Considering the long-term trend of streamwater chemistry, the electric conductivity (EC), Cl-, and SO42- concentrations have been gradually decreasing during recent 10 years in all catchments. On the other hand, the NO3- concentration has been commonly increasing in recent 5 years in all catchment. The difference of concentrations between the catchments were depending on the difference of the redox condition caused by soil sediment. One of the subcatchments experienced the disturbance in early 90's and subsequent increase of NO3- concentration, and the residence tine distribution shows the effects of the disturbance is still remaining. Recently, the disturbance is expanding in another subcatchment, and one of the reason of the disturbance is soil erosion. Moreover, the streamwater NO3- concentrations are also gradually increasing even in undisturbed catchments. These facts imply that this 50-year-old unmanaged artificial forest may start degrading, and the biogeochemical cycle may start changing. The long-term dynamics of streamwater chemistry is a good diagnosis tool of the

  17. What do spatio-temporal signals in stream nutrient export from naturally forested landscapes teach us about catchment form and function? (Invited)

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Mengistu, S. G.; Lutz, B. D.

    2013-12-01

    Statistical deconstruction of stream solute signals can provide a window into underlying catchment form and function on natural landscapes. Our conceptual model is that stream nutrient export signals reflect catchment form and by extension catchment function related to water table dynamics that influence the timing, size, configuration and redox conditions of saturated and inundated areas within catchments. When the water table is low, nutrients accumulate; when the water table rises towards the surface, nutrients are flushed to the stream; and when the water table resides near or at the ground surface, the redox conditions can change, altering the fate of nutrients. We test the hypothesis that stream water and solute signals show statistically significant differences from each other due to differences in catchment form and/or function. We selected catchments in an old growth tolerant hardwood forest in the Great Lakes-St. Lawrence Forest Region that represent a gradient in catchment form, which has previously been shown to influence the size, configuration and connectivity (permanent vs. transient connections) of surface saturated and inundated conditions. For each catchment along this gradient, we examined both conservative solute signals (e.g., Na and Cl because they are not influenced by changing redox conditions) and non-conservative solute signals (e.g., C, N, P and Fe because they are reactive to changing redox conditions). We used statistical techniques (both regression and wavelet analyses) on the time series to show that (1) conservative solutes had strong positive associations with discharge (i.e., were not reactive) and non-conservative solutes did not (i.e., were reactive). This suggests that non-conservative solutes are not simply linked to the amount of water flowing from the catchment, but to the partitioning (surface, shallow subsurface, or deep subsurface) and pathways of water flow that are related specifically to the magnitude, timing, frequency

  18. Prior exposure influences the behavioural avoidance by an intertidal gastropod, Bembicium auratum, of acidified waters

    NASA Astrophysics Data System (ADS)

    Amaral, Valter; Cabral, Henrique N.; Bishop, Melanie J.

    2014-01-01

    Phenotypic plasticity may be critical to the maintenance of viable populations under future environmental change. Here we examined the role of behavioural avoidance of sub-optimal conditions in enabling the intertidal gastropod, Bembicium auratum, to persist in mangrove forests affected by the low pH runoff from acid sulphate soils (ASS). Behaviourally, the gastropod may be able to avoid periods of particularly high acidity by using pneumatophores and/or mangrove trunks to vertically migrate above the water line or by retreating into its shell. We hypothesised that (1) B. auratum would display greater and more rapid vertical migration out of acidified than reference estuarine waters, and (2) responses would be more pronounced in gastropods collected from acidified than reference sites. Gastropods from acidified sites showed significantly higher activity in and more rapid migration out of acidified waters of pH 6.2-7.0, than reference waters or waters of pH < 5.0. Gastropods from reference locations showed a significantly weaker response to acidified water than those from acidified waters, and which did not significantly differ from their response to reference water. At extremely low pHs, <5.0, a higher proportion of both acidified and reference gastropods retreated into their shell than at higher pHs. Both the migration of gastropods out of acidified waters and retraction into their shells serves to reduce exposure time to acidified waters and may reduce the impact of this stressor on their populations. The stronger response to acidification of gastropods from populations previously exposed to this stressor suggests that the response may be learned, inherited or induced over multiple exposures. Our study adds to growing evidence that estuarine organisms may exhibit considerable physiological and behaviour adaptive capacity to acidification. The potential for such adaptive capacity should be incorporated into studies seeking to forecast impacts to marine organisms

  19. Forest management for water: a hydro-ecological modeling exercise of headwater catchments in the mixed-conifer belt of the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Bales, R. C.; Ray, R. L.

    2011-12-01

    Hydro-ecological modeling provides a cost-effective method for evaluating the effects of vegetation change on water cycling within a catchment. In mountain watersheds, change in forest vegetation not only has direct effects on transpiration rates, but also energy exchanges that influence patterns of snow ablation. In this study, treatment scenarios were implemented using the Regional Hydro-Ecological Simulation System (RHESSys) to estimate impacts on key elements of the hydrologic cycle affected by forest harvesting - snowpack accumulation, ablation, transpiration, and streamflow. Twelve headwater catchments (0.5 - 2.6 km2, 1460 - 2450m) in the mixed-conifer zone of the central Sierra Nevada, within the Sierra and Tahoe National Forests, were included for analysis. These research sites are part of the Sierra Nevada Adaptive Management Project (SNAMP), located in the headwaters of the American and Merced Rivers, and the Southern Sierra Critical Zone Observatory (CZO) in the Kings River basin. Two methods of forest harvesting were simulated in the study watersheds: 1) uniform canopy thinning, through reduction of Leaf Area Index (LAI) values and 2) strip-cut treatments, suggested as the best method for retaining snowpack. Results from this study compare the influence of vegetation on water cycle dynamics through the two harvesting treatments, initial vegetation densities, and individual catchment size. Model simulations for pre-treatment snow depth, soil moisture, and streamflow were validated with SNAMP and CZO in-situ measurements. Preliminary results show that a linear reduction of forest canopy reduces transpiration accordingly, but produces a non-linear increase in streamflow. Peak discharges also increased, occurring earlier in the spring and having more pronounced effects in the smaller catchments. Based on these results, harvesting thresholds required for obtaining increases in water yield are evaluated. Investigating the impact of forest management on these

  20. Controls on denitrification in riparian soils in headwater catchments of a hardwood forest in the Catskill Mountains, U.S.A.

    USGS Publications Warehouse

    Ashby, J.A.; Bowden, W.B.; Murdoch, Peter S.

    1998-01-01

    Denitrification in riparian soils is thought to be an important factor that reduces hydrologic export of nitrate from forested and agricultural catchments. A 2-y study to identify the soil factors most closely associated with denitrification in riparian soils in headwater catchments within the Catskill Mountains of New York, included field surveys of surface and subsurface denitrification rates, and an amendment experiment to assess the relative effects of increases in available carbon and substrate NO-/3 on denitrification rates. Denitrification rates were measured by acetylene inhibition during incubation of intact soil cores from eight soil types representing a range of drainage classes. Soil cores were analyzed for organic matter, total P, extractable NO-/3-N and NH+/4-N, organic N, pH, moisture, porosity, and water-filled pore space, to determine which of these factors were most closely associated with denitrification. The distribution of denitrification rates found during the field surveys was highly skewed, with many low or zero values and few high values. Denitrification rates were positively associated with high soil organic matter, total P, and water-filled pore space, and were highest in seep (poorly-drained) soils, toeslope (seasonally-drained) soils, and stream-edge (poorly- to moderately well-drained) soils in which these three soil characteristics were typically high. Denitrification rates in these wet locations were also positively associated with soil NH+/4-N concentration and pH, but not with NO-/3-N concentration, suggesting that the rate of NO-/3 supply (via nitrification or hydrologic transport) was more important than the instantaneous concentration of NO-/3-N in the soils. The amendment experiment indicated that denitrification in soil types studied was most responsive to added glucose alone or with NO-/3. Thus, in these soils, a combination of slow rates of NO-/3 supply and low available carbon appears to limit denitrification. Annual

  1. Analysis and Model Based Assessment of Water Quality in European Mesoscale Forest Catchments with Different Management Strategies (a Climatic Gradient Approach)

    NASA Astrophysics Data System (ADS)

    Tavares, Filipa; Schwaerzel, Kai; Nunes, João. Pedro; Feger, Karl-Heinz

    2010-05-01

    Forestry activities affect the environmental conditions of river basins by modifying soil properties and vegetation cover, leading to changes in e.g. runoff generation and routing, water yield or the trophic status of water bodies. Climate change is directly linked to forestry, since site-adapted sustainable forest management can buffer negative climate change impacts in river basins, while practices leading to over-harvesting or increasing wildfires can exacerbate these impacts. While studies relating hydrological processes with forestry practices or climate change have already been conducted, the combined impacts of both are rarely discussed. The main objective of the proposed work is to study the interactions between forest management and climate change and the effects of these upon water fluxes and water quality at the catchment scale, over medium to long-term periods and following an East-West climate gradient. Additional objectives are to increase knowledge about the relations between forest, water quality and soil conservation/degradation; and to improve the modelling of hydrological and matter transport processes in managed forests. The present poster shows a conceptual approach to understand this combined interaction by analysing an East-West climatic gradient (Ukraine-Germany-Portugal), with contrasting forestry practices and climate vulnerabilities. The activities within this workplan, to take place during the period 2010 - 2014, will be developed in close collaboration with several ongoing research projects in the host institution at the Dresden University of Technology (TUD) and in the University of Aveiro (UA). The Institute of Soil Science and Site-Ecology (ISSE) at TUD has an internationally renowned research tradition in forest hydrological topics using methods and findings from various (sub)disciplines in a multidisplinary approach. The measurement and simulation of forest catchments has also been a point of research at the Centre for

  2. [Study the restoration technology of concentrated application-natural diffusion about amendments of acidified soil of hilly woodland].

    PubMed

    Fang, Xiong; Liu, Ju-Xiu; Yin, Guang-Cai; Zhao, Liang; Liu, Shi-Zhong; Chu, Guo-Wei; Li, Yi-Yong

    2013-01-01

    Through concentrated application of lime, sewage sludge and lime + sewage sludge on the sloping top of the hilly woodlands, the restoration effects of the three soil amendments on the acidified soil of hilly woodland were studied. The results showed that: (1) Joint application of sewage sludge + lime can significantly (P < 0.05) decrease soil acidity, promote the rapid increase in soil organic matter and nitrogen content, increase soil cation exchange capacity, and effectively improve acidified soil. (2) Through natural diffusion mechanisms of surface and subsurface runoff, a large area of acidified soil of hilly woodlands can be restored by concentrated application of soil amendments on the sloping top of the hilly woodlands. (3) It is conducive to solve the pollution problems of the urban sewage sludge by using municipal sewage sludge to restore acidified soil, but only for the restoration of acidified soil of timber forest. PMID:23487954

  3. Comparison of hydrochemical tracers to estimate source contributions to peak flow in a small, forested, headwater catchment

    USGS Publications Warehouse

    Rice, K.C.; Hornberger, G.M.

    1998-01-01

    Three-component (throughfall, soil water, groundwater) hydrograph separations at peak flow were performed on 10 storms over a 2-year period in a small forested catchment in north-central Maryland using an iterative and an exact solution. Seven pairs of tracers (deuterium and oxygen 18, deuterium and chloride, deuterium and sodium, deuterium and silica, chloride and silica, chloride and sodium, and sodium and silica) were used for three-component hydrograph separation for each storm at peak flow to determine whether or not the assumptions of hydrograph separation routinely can be met, to assess the adequacy of some commonly used tracers, to identify patterns in hydrograph-separation results, and to develop conceptual models for the patterns observed. Results of the three-component separations were not always physically meaningful, suggesting that assumptions of hydrograph separation had been violated. Uncertainties in solutions to equations for hydrograph separations were large, partly as a result of violations of assumptions used in deriving the separation equations and partly as a result of improper identification of chemical compositions of end-members. Results of three-component separations using commonly used tracers were widely variable. Consistent patterns in the amount of subsurface water contributing to peak flow (45-100%) were observed, no matter which separation method or combination of tracers was used. A general conceptual model for the sequence of contributions from the three end-members could be developed for 9 of the 10 storms. Overall results indicated that hydrochemical and hydrometric measurements need to be coupled in order to perform meaningful hydrograph separations.

  4. Understanding mean transit times in Andean tropical montane cloud forest catchments: combining tracer data, lumped parameter models and uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Timbe, E.; Windhorst, D.; Crespo, P.; Frede, H.-G.; Feyen, J.; Breuer, L.

    2013-12-01

    Weekly samples from surface waters, springs, soil water and rainfall were collected in a 76.9 km2 mountain rain forest catchment and its tributaries in southern Ecuador. Time series of the stable water isotopes δ18O and δ2H were used to calculate mean transit times (MTTs) and the transit time distribution functions (TTDs) solving the convolution method for seven lumped parameter models. For each model setup, the Generalized Likelihood Uncertainty Estimation (GLUE) methodology was applied to find the best predictions, behavioral solutions and parameter identifiability. For the study basin, TTDs based on model types such as the Linear-Piston Flow for soil waters and the Exponential-Piston Flow for surface waters and springs performed better than more versatile equations such as the Gamma and the Two Parallel Linear Reservoirs. Notwithstanding both approaches yielded a better goodness of fit for most sites, but with considerable larger uncertainty shown by GLUE. Among the tested models, corresponding results were obtained for soil waters with short MTTs (ranging from 3 to 12 weeks). For waters with longer MTTs differences were found, suggesting that for those cases the MTT should be based at least on an intercomparison of several models. Under dominant baseflow conditions long MTTs for stream water ≥2 yr were detected, a phenomenon also observed for shallow springs. Short MTTs for water in the top soil layer indicate a rapid exchange of surface waters with deeper soil horizons. Differences in travel times between soils suggest that there is evidence of a land use effect on flow generation.

  5. Highly Resolved Long-term 3D Hydrological Simulation of a Forested Catchment with Litter Layer and Fractured Bedrock

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Bogena, H. R.; Kollet, S. J.; Vereecken, H.

    2014-12-01

    Soil water content plays a key role in the water and energy balance in soil, vegetation and atmosphere systems. According to Wood et al. (2011) there is a grand need to increase global-scale hyper-resolution water-energy-biogeochemistry land surface modelling capabilities. However, such a model scheme should also recognize the epistemic uncertainties, as well as the nonlinearity and hysteresis in its dynamics. Unfortunately, it is not clear how to parameterize hydrological processes as a function of scale and how to test deterministic models with regard to epistemic uncertainties. In this study, high resolution long-term simulations were conducted in the highly instrumented TERENO hydrological observatory, the Wüstebach catchment. Soil hydraulic parameters were derived using inverse modeling with the Hydrus-1D model using the global optimization scheme SCE-UA and soil moisture data from a wireless soil moisture sensor network. The estimated parameters were then used for 3D simulations using the integrated parallel simulation platform ParFlow-CLM. The simulated soil water content, as well as evapotranspiration and runoff, were compared with long-term field observations to illustrate how well the model was able to reproduce the water budget dynamics. With variable model setup scenarios in boundary conditions and anisotropy of hydraulic conductivity, we investigated how lateral flow processes above the underlying fractured bedrock affects the simulation results. Furthermore, we explored the importance of the litter layer and the heterogeneity of the forest soil in the simulation of flow processes and model performance. For the analysis of spatial patterns of simulated and observed soil water content we applied the method of empirical orthogonal function (EOF). The results suggest that strong anisotropy in the hydraulic conductivity may be the reason for the fast lateral flow observed in Wüstebach. Introduction of heterogeneity in the hydraulic properties in the

  6. Quantitative importance of denitrification and N2O emission in an N-saturated subtropical forest catchment, southwest China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Dörsch, P.; Mulder, J.

    2009-04-01

    Anthropogenic emission of nitrogen in the environment has increased rapidly, due to fast economic growth. This has resulted in increased deposition rates of reactive nitrogen, primarily as NOx (from fossil fuel combustion) and NH3 (from fertilizer production and animal husbandry). In response, temperate and boreal forests may develop nitrogen saturation, characterized by increased leaching of nitrate. In addition, elevated emission of N2 and N2O, due to nitrification and denitrification, may occur. To date, few studies exist quantifying the nitrogen balance, including N2 and N2O production, in nitrogen-saturated, monsoonal, sub-tropical forest ecosystems in south-west China. Since nitrate contributes to the eutrophication of stream water, and N2O is a potent greenhouse gas, it is important to quantitatively understand the role of nitrification and denitrification in the nitrogen cycle. Several subtropical forests in southwest China, receiving elevated nitrogen deposition (30-73 kg N ha-1 a-1; Zhang. et al., 2008), are characterized by high temperature and soil moisture content in much of the growing season. This may cause a much stronger intensity of denitrification compared with that in temperate and boreal forests. In turn this may lead to decreased nitrate leaching and a higher potential of N2O emission. In my PhD project, I will investigate the nitrogen cycle in a forest catchment (TieShanPing; TSP), which is near one of the biggest cities, Chongqing, in southwest China. Previous research suggests high nitrogen deposition (3.52 gN m-2 a-1), but low nitrogen flux (0.57 gN m-2 a-1) in runoff (Chen & Mulder, 2007). Tree growth, and thus plant N uptake, is limited and nitrate fluxes below the root zone are relatively large, suggesting ‘N-saturation'. Based on this, we hypothesize that significant amounts of nitrogen are emitted as gases, with denitrification playing an important role, and N2 and N2O (especially N2) being major components of the emitted gases

  7. Hydro-meteorological functioning of the Eastern Andean Tropical Montane Cloud Forests: Insight from a paired catchment study in the Orinoco river basin highlands

    NASA Astrophysics Data System (ADS)

    Ramirez, Beatriz; Teuling, Adriaan J.; Ganzeveld, Laurens; Leemans, Rik

    2016-04-01

    Tropical forests regulate large scale precipitation patterns and catchment-scale streamflow, while tropical mountains influence runoff by orographic effects and snowmelt. Along tropical elevation gradients, these climate/ecosystem/hydrological interactions are specific and heterogeneous. These interactions are poorly understood and represented in hydro-meteorological monitoring networks and regional or global earth system models. A typical case are the South American Tropical Montane Cloud Forests (TMCF), whose water balance is strongly driven by fog persistence. This also depends on local and up wind temperature and moisture, and changes in this balance alter the impacts of changes in land use and climate on hydrology. These TMCFs were until 2010 only investigated up to 350km from the coast. Continental TMCFs are largely ignored. This gap is covered by our study area, which is part of the Orinoco river basin highlands and located on the northern Eastern Andes at an altitudinal range of 1550 to 2300m a.s.l. The upwind part of our study area is dominated by lowland savannahs that are flooded seasonally. Because meteorological stations are absent in our study area, we first describe the spatial and seasonal meteorological variability and analyse the corresponding catchment hydrology. Our hydro-meteorological data set is collected at three gauged neighbouring catchments with contrasting TMCF/grassland cover from June 2013 to May 2014 and includes hourly solar radiation, temperature, relative humidity, wind speed, precipitation, soil moisture and runoff measurements. We compare our results with recent TCMF studies in the eastern Andean highlands in the Amazon basin. The studied elevational range always shows wetter conditions at higher elevations. This indicates a positive relation between elevation and fog or rainfall persistence. Lower elevations are more seasonally variable. Soil moisture data indicate that TMCFs do not use persistently more water than grasslands

  8. Effects of biogeochemical processes on magnesium isotope variations in a forested catchment in the Vosges Mountains (France)

    NASA Astrophysics Data System (ADS)

    Bolou-Bi, Emile B.; Vigier, Nathalie; Poszwa, Anne; Boudot, Jean-Pierre; Dambrine, Etienne

    2012-06-01

    This study investigates the potential of Mg isotopes as tracers of biogeochemical processes in a small-forested catchment located on sandstones extremely poor in Mg-bearing minerals. The average δ26Mg is -0.63 ± 0.12‰ and 0 ± 0.14‰ for local rainwater and bedrock, respectively. From the C horizon to the upper eluvial (E) horizon, soil δ26Mg (from 0.0 ± 0.14‰ to 0.25 ± 0.14‰) is close to the bedrock value, while more than 70% of Mg is lost, suggesting a small isotopic shift during illite dissolution. The surface soil horizon (Ah) δ26Mg is close to plant δ26Mg, and especially to the grass δ26Mg value (-0.49‰). The bulk δ26Mg of trees and grass (-0.32‰ and -0.41‰, respectively) are higher than the average δ26Mg values of the soil exchangeable fraction (-0.92‰ to -0.42‰), and of rainwater (-0.65‰). Within plants, roots are enriched in heavy isotopes, whereas light isotopes are preferentially translocated and stored in the above ground parts. In Norway spruce, the older needles, forming the annual litterfall, are isotopically lighter and strongly depleted in Mg compared to more recent needles. Soil solution δ26Mg shifts seasonally, from low values, lower than rainwater and close to litterfall during a high rainfall period in spring, to higher values, close to soil δ26Mg in dryer periods of winter or summer. At the watershed scale, streamwater δ26Mg varies between -0.85 ± 0.14‰ and -0.08 ± 0.14‰ and δ26Mg values decrease linearly with discharge. The high streamwater δ26Mg at low flow, close to bedrock δ26Mg, most likely reflects dissolution processes in the deep saprolite in relation to the very long water residence time. Conversely, we suggest that low stream level δ26Mg values are at least partly related to the contribution of surface flows from wet areas. Using a simple mass and isotopic balance approach, we compute that mineral dissolution rates in the soil (0.35 kg Mg ha-1 year-1) presently compensate for Mg losses from

  9. Microbiological Spoilage of Acidified Specialty Products

    NASA Astrophysics Data System (ADS)

    Sperber, William H.

    Acidified specialty products or condiments are among the most microbiologically stable and safe food products. Often formulated, packaged, and distributed without heat treatments, they are microbiologically stable indefinitely at ambient temperatures in unopened containers. The packaged, acidified products are often intended for multiple uses, exposing them at the points of consumption to numerous opportunities for contamination with microorganisms. Nonetheless, they remain resistant to microbiological spoilage for many months, often under refrigerated conditions that are used to retard chemical reactions, flavor changes, and yeast growth.

  10. Coupled soil respiration and transpiration dynamics from tree-scale to catchment scale in dry Rocky Mountain pine forests and the role of snowpack

    NASA Astrophysics Data System (ADS)

    Berryman, E.; Barnard, H. R.; Brooks, P. D.; Adams, H.; Burns, M. A.; Wilson, W.; Stielstra, C. M.

    2013-12-01

    A current ecohydrological challenge is quantifying the exact nature of carbon (C) and water couplings across landscapes. An emerging framework of understanding places plant physiological processes as a central control over soil respiration, the largest source of CO2 to the atmosphere. In dry montane forests, spatial and temporal variability in forest physiological processes are governed by hydrological patterns. Critical feedbacks involving respiration, moisture supply and tree physiology are poorly understood and must be quantified at the landscape level to better predict carbon cycle implications of regional drought under future climate change. We present data from an experiment designed to capture landscape variability in key coupled hydrological and C processes in forests of Colorado's Front Range. Sites encompass three catchments within the Boulder Creek watershed, range from 1480 m to 3021 m above sea level and are co-located with the DOE Niwot Ridge Ameriflux site and the Boulder Creek Critical Zone Observatory. Key hydrological measurements (soil moisture, transpiration) are coupled with soil respiration measurements within each catchment at different landscape positions. This three-dimensional study design also allows for the examination of the role of water subsidies from uplands to lowlands in controlling respiration. Initial findings from 2012 reveal a moisture threshold response of the sensitivity of soil respiration to temperature. This threshold may derive from tree physiological responses to variation in moisture availability, which in turn is controlled by the persistence of snowpack. Using data collected in 2013, first, we determine whether respiration moisture thresholds represent triggers for transpiration at the individual tree level. Next, using stable isotope ratios of soil respiration and xylem and soil water, we compare the depths of respiration to depths of water uptake to assign tree vs. understory sources of respiration. This will help

  11. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... continuous inspection of the meat and poultry inspection program of the Food Safety and Inspection Service of... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Acidified foods. 108.25 Section 108.25 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR...

  12. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Acidified foods. 108.25 Section 108.25 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION EMERGENCY PERMIT CONTROL Specific Requirements and Conditions for Exemption From or Compliance With an Emergency Permit §...

  13. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... continuous inspection of the meat and poultry inspection program of the Food Safety and Inspection Service of... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Acidified foods. 108.25 Section 108.25 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR...

  14. Chemical behavior of acidified chromium (3) solutions

    SciTech Connect

    Terman, D.K.

    1981-05-01

    A unique energy-storage system has been developed at NASA's Lewis Research Center called REDOX. This NASA-REDOX system is an electrochemical storage device that utilized the oxidation and reduction of two fully soluble redox couples for charging and discharging. The redox couples now being investigated are acidified chloride solutions of chromium (Cr(+2)/Cr(+3)) and iron (Fe(+2)/Fe(+3)).

  15. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Acidified foods. 108.25 Section 108.25 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... after these foods have entered into interstate commerce. The Commissioner of Food and Drugs...

  16. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Acidified foods. 108.25 Section 108.25 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION EMERGENCY PERMIT CONTROL Specific Requirements and Conditions for Exemption From or Compliance With an Emergency Permit §...

  17. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... with safe and suitable acidifiers, with or without addition of lactic acid producing bacteria.... Acidified sour cream has a titratable acidity of not less than 0.5 percent, calculated as lactic acid....

  18. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... with safe and suitable acidifiers, with or without addition of lactic acid producing bacteria.... Acidified sour cream has a titratable acidity of not less than 0.5 percent, calculated as lactic acid....

  19. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... with safe and suitable acidifiers, with or without addition of lactic acid producing bacteria.... Acidified sour cream has a titratable acidity of not less than 0.5 percent, calculated as lactic acid....

  20. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... with safe and suitable acidifiers, with or without addition of lactic acid producing bacteria.... Acidified sour cream has a titratable acidity of not less than 0.5 percent, calculated as lactic acid....

  1. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... with safe and suitable acidifiers, with or without addition of lactic acid producing bacteria.... Acidified sour cream has a titratable acidity of not less than 0.5 percent, calculated as lactic acid....

  2. Use of a (137)Cs re-sampling technique to investigate temporal changes in soil erosion and sediment mobilisation for a small forested catchment in southern Italy.

    PubMed

    Porto, Paolo; Walling, Des E; Alewell, Christine; Callegari, Giovanni; Mabit, Lionel; Mallimo, Nicola; Meusburger, Katrin; Zehringer, Markus

    2014-12-01

    Soil erosion and both its on-site and off-site impacts are increasingly seen as a serious environmental problem across the world. The need for an improved evidence base on soil loss and soil redistribution rates has directed attention to the use of fallout radionuclides, and particularly (137)Cs, for documenting soil redistribution rates. This approach possesses important advantages over more traditional means of documenting soil erosion and soil redistribution. However, one key limitation of the approach is the time-averaged or lumped nature of the estimated erosion rates. In nearly all cases, these will relate to the period extending from the main period of bomb fallout to the time of sampling. Increasing concern for the impact of global change, particularly that related to changing land use and climate change, has frequently directed attention to the need to document changes in soil redistribution rates within this period. Re-sampling techniques, which should be distinguished from repeat-sampling techniques, have the potential to meet this requirement. As an example, the use of a re-sampling technique to derive estimates of the mean annual net soil loss from a small (1.38 ha) forested catchment in southern Italy is reported. The catchment was originally sampled in 1998 and samples were collected from points very close to the original sampling points again in 2013. This made it possible to compare the estimate of mean annual erosion for the period 1954-1998 with that for the period 1999-2013. The availability of measurements of sediment yield from the catchment for parts of the overall period made it possible to compare the results provided by the (137)Cs re-sampling study with the estimates of sediment yield for the same periods. In order to compare the estimates of soil loss and sediment yield for the two different periods, it was necessary to establish the uncertainty associated with the individual estimates. In the absence of a generally accepted procedure

  3. In Vitro Killing of Mycobacterium ulcerans by Acidified Nitrite

    PubMed Central

    Phillips, R.; Kuijper, S.; Benjamin, N.; Wansbrough-Jones, M.; Wilks, M.; Kolk, A. H. J.

    2004-01-01

    Mycobacterium ulcerans, which causes Buruli ulcer, was exposed to acidified nitrite or to acid alone for 10 or 20 min. Killing was rapid, and viable counts were reduced below detectable limits within 10 min of exposure to 40 mM acidified nitrite. M. ulcerans is highly susceptible to acidified nitrite in vitro. PMID:15273132

  4. Examining the linkages between forest water use, hydrology, and climate using dual-isotope approaches: insights and challenges in headwater catchments (Invited)

    NASA Astrophysics Data System (ADS)

    Barnard, H. R.; Brooks, J. R.; Pypker, T. G.; McDonnell, J. J.; Bond, B. J.; Williams, D. G.

    2010-12-01

    The amount of biologically available water is arguably the central driver in plant processes. While many studies have examined the hydrological components of biologically available water, the role that vegetation water use plays within the forested ecosystem water balance is poorly understood. Fundamental questions of forests' effect on the hydrologic cycle remain unanswered. Stable isotope observations play an important role in studies that explore the interface between plant physiological function and watershed flowpaths, flow sources, and residence times. We use multiple approaches, including stable isotopes to mechanistically assess the inter-relationships between vegetation water use, hydrology, and climate. We measured deuterium and 18O of xylem water and soil water to track changes in the depth of transpiration source water throughout the summers in a headwater catchment in western Oregon. Additionally, we measured transpiration, soil moisture, and foliar pre-dawn water potential. Forest transpiration and soil evaporation are often not separately measured, and yet respond to environmental drivers in fundamentally different ways. A promising approach for partitioning the evapotranspiration into its component fluxes involves measurement of the stable isotope composition (2H and 18O) of water vapor exchanged between vegetation and atmosphere. We present some preliminary data examining changes in ET partitioning in response to bark beetles outbreaks in the Rocky Mountains. Last, to examine the linkages between vegetation function and micro-climate, we applied a dual isotope (13C and 18O) approach to infer physiological response of trees to changing environmental conditions. We found that stable isotopes of oxygen were directly related to stomatal conductance and inversely related to relative humidity; however, the relationship with relative humidity was more apparent. The correlation of stable isotopes in tree rings with environmental variables can be

  5. Three-dimensional prediction of soil physical, chemical, and hydrological properties in a forested catchment of the Santa Catalina CZO

    NASA Astrophysics Data System (ADS)

    Shepard, C.; Holleran, M.; Lybrand, R. A.; Rasmussen, C.

    2014-12-01

    Understanding critical zone evolution and function requires an accurate assessment of local soil properties. Two-dimensional (2D) digital soil mapping provides a general assessment of soil characteristics across a sampled landscape, but lacks the ability to predict soil properties with depth. The utilization of mass-preserving spline functions enable the extrapolation of soil properties with depth, extending predictive functions to three-dimensions (3D). The present study was completed in the Marshall Gulch (MG) catchment, located in the Santa Catalina Mountains, 30 km northwest of Tucson, Arizona, as part of the Santa Catalina-Jemez Mountains Critical Zone Observatory. Twenty-four soil pits were excavated and described following standard procedures. Mass-preserving splines were used to extrapolate mass carbon (kg C m-2); percent clay, silt, and sand (%); sodium mass flux (kg Na m-2); and pH for 24 sampled soil pits in 1-cm depth increments. Saturated volumetric water content (θs) and volumetric water content at 10 kPa (θ10) were predicted using ROSETTA and established empirical relationships. The described profiles were all sampled to differing depths; to compensate for the unevenness of the profile descriptions, the soil depths were standardized from 0.0 to 1.0 and then split into five equal standard depth sections. A logit-transformation was used to normalize the target variables. Step-wise regressions were calculated using available environmental covariates to predict the properties of each variable across the catchment in each depth section, and interpolated model residuals added back to the predicted layers to generate the final soil maps. Logit-transformed R2 for the predictive functions varied widely, ranging from 0.20 to 0.79, with logit-transformed RMSE ranging from 0.15 to 2.77. The MG catchment was further classified into clusters with similar properties based on the environmental covariates, and representative depth functions for each target variable

  6. Climate and Landuse Change Impacts on hydrological processes and soil erosion in a dry Mediterranean agro-forested catchment, southern Portugal

    NASA Astrophysics Data System (ADS)

    Santos, Juliana; Nunes, João Pedro; Sampaio, Elsa; Moreira, Madalena; Lima, Júlio; Jacinto, Rita; Corte-Real, João

    2014-05-01

    Climate change is expected to increase aridity in the Mediterranean rim of Europe, due to decreasing rainfall and increasing temperatures. This could lead to impacts on soil erosion, since the lower rainfall could nevertheless become concentrated in higher intensity events during the wet season, while the more arid conditions could reduce vegetation cover, also due to climate-induced land-use changes. In consequence, there is an interest in understanding how climate change will affect the interaction between the timing of extreme rainfall events, hydrological processes, vegetation growth, soil cover and soil erosion. To study this issue, the SWAT eco-hydrological model was applied to Guadalupe, an agro-forested catchment (446 ha) located close to the city of Évora, with a Mediterranean inland climate. The landcover is a mix of dispersed cork oak forests ("montado"), annual crops, and agroforesty regions where the cork oaks are associated with crops or pasture; this land cover is representative of the dry regions of southern Portugal and Spain. The catchment has been instrumented since 2011 with a hydrometric station (water discharge and suspended sediment concentration data) and a soil moisture measurement station. There is also observed data of actual evapotranspiration, LAI and biomass production (in pasture; from 1999 and 2008) and runoff data and sediment yield measured in six 16m2 plots. Water balance, vegetation growth, soil erosion and sediment yield in SWAT was calibrated with this dataset. This work will present the dataset, modeling process, results for impacts of climate and land-use change scenarios for vegetation growth, soil erosion and sediment export, considering the climate and socio-economic scenarios A1b and B1 (based on SRES storylines). Climate scenarios were created by statistical downscaling from Global Circulation Models (GCMs) for the period 2071-2100 (30 years). The reference period was 1971-2000 (30 years). The SWAT model was used to

  7. Soil Microbial Nitrogen Cycling Responses to Wildfire in a High Elevation Forested Catchment in Jemez Mountains, NM

    NASA Astrophysics Data System (ADS)

    Murphy, M. A.; Fairbanks, D.; Chorover, J.; Rich, V. I.; Gallery, R. E.; Boyer, J. C.

    2015-12-01

    Microbial communities mediate major ecosystem processes such as nutrient cycling, and their recovery after disturbances plays a substantial role in overall ecosystem recovery and resilience. Disturbances directly shift microbial communities and their related processes, and the severity of impact typically varies significantly with landscape position, depth, and hydrological conditions such that different conditions indicate that a specific process will be dominant. Wildfires in the southwest US are a major source of landscape-scale disturbance, and are predicted to continue increasing in size and intensity under climate change. This study investigates changing nitrogen cycling across a post-wildfire catchment within the Jemez River Basin Critical Zone Observatory. This site experienced a mixed (intermediate to high) burn severity wildfire in June 2013. Nitrogen cycling was investigated by profiling via qPCR the abundance of five key genes involved in microbial nitrogen cycling (nifH, amoA, nirS, nirK, nosZ), at points along and within the catchment. These results are being analyzed in the context of broader microbial community data (enzyme assays, microbial cell counts and biomass, and 16S rRNA gene amplicons surveys) and biogeochemical data (total organic carbon, total nitrogen, pH, graviametric water content, etc). W 22 sites along the sides of the basin (planar zones) and within the hollow (convergent zone) were sampled at 13 days, one, and two years post-fire, at six discrete depth increments from 0 to 40 cm from the surface. We attribute significance of variation in gene abundance in planar versus convergent zones, and among depths, to the strong correlation of nitrogen cycling processes (i.e., nitrification and denitrification) with specific C:N ratios, total organic carbon content, and other biogeochemical and soil edaphic parameters that vary with landscape position and wildfire. Data were also interrogated for evidence of multi-year patterns in nutrient

  8. Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    NASA Astrophysics Data System (ADS)

    Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro

    2016-04-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected

  9. Forest runoff increase mercury output from subtropical forest catchments: an example from an alpine reservoir in a national nature reserve (southwestern China).

    PubMed

    Ma, Ming; Wang, Dingyong; Sun, Tao; Zhao, Zheng; Du, Hongxia

    2015-02-01

    For a typical alpine forest reservoir that does not have other obvious mercury pollution sources, mercury levels in its downstream water can reflect the characteristics of mercury inputs and risks of a remote forest. To confirm this proposal, eight sampling campaigns were carried out in 2012 and 2013 to investigate the distribution patterns of Hg species in the water column and sediment profiles at four sampling stations in an alpine forest reservoir, southwestern China. The concentrations of total Hg (THg) and methylmercury (MeHg) in water samples of DaHong Reservoir varied from 2.8 to 8.2 ng L(-1) and 0.06 to 2.9 ng L(-1), respectively. The concentrations of these Hg species in the wet seasons (summer and fall) were significantly higher than those in the dry season (winter and spring). Forest field runoff and diffusion of Hg from sediments could be the reasons for elevated concentrations of these Hg species in the wet season. Elevated MeHg concentrations in water samples from the bottom water and water-sediment interface demonstrated an active net Hg methylation in the downstream of DaHong (DH) Reservoir. Dissolved MeHg levels in the pore water of surface sediments and the bottom of downstream were apparently higher than those in the upstream, which indicated that MeHg sources of sediment pore water varied in space. MeHg diffusive fluxes from sediment to overlying water were higher in the wet season than those in the dry season, demonstrating that high temperatures favor Hg methylation processes in sediment. PMID:25205157

  10. Comparisons of Aquatic Invertebrate Assemblages in Small, Old Growth and Second Growth Forested Catchments of the H.J. Andrews Experimental Forest, Oregon

    NASA Astrophysics Data System (ADS)

    Frady, C. H.; Johnson, S. L.; Li, J. L.

    2005-05-01

    In small streams, riparian vegetation often composes the food base for many aquatic invertebrates. Forest harvest can result in major changes to riparian vegetation. If abundance, richness, or community structure of invertebrate assemblages is affected by removal of riparian vegetation, are legacies of these practices evident 20-40 years post-harvest? If so, are these differences uniform through time, or are they temporally dependant? We investigated stream invertebrate assemblage dynamics between old growth and second growth forest types and across seasons in six small-basins in the H.J. Andrews Experimental Forest. Individual basins range from 500m to 1000m in elevation and 12.4ha to 98.1ha in area. Six benthic samples and four, 1-week emergence samples were collected in each basin each season (June 2003 through May 2004). Preliminary results from benthic samples suggest strong changes in community structure between seasons as additional taxa not found in summer (i.e. Agathon, Anagapetus, Chernokrilus, and Rhyacophila "angelita group") were collected in autumn and winter samples. However, results from summer comparisons demonstrate no differences in benthic and emergence abundance (p = 0.47, and p = 0.98, respectively) or benthic richness (p = 0.41) between old growth and second growth invertebrate assemblages.

  11. Scale dependent parameterization of soil hydraulic conductivity in 3D simulation of hydrological processes in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Fang, Zhufeng; Bogena, Heye; Kollet, Stefan; Vereecken, Harry

    2016-05-01

    In distributed hydrological modelling one often faces the problem that input data need to be aggregated to match the model resolution. However, aggregated data may be too coarse for the parametrization of the processes represented. This dilemma can be circumvented by the adjustment of certain model parameters. For instance, the reduction of local hydraulic gradients due to spatial aggregation can be partially compensated by increasing soil hydraulic conductivity. In this study, we employed the information entropy concept for the scale dependent parameterization of soil hydraulic conductivity. The loss of information content of terrain curvature as consequence of spatial aggregation was used to determine an amplification factor for soil hydraulic conductivity to compensate the resulting retardation of water flow. To test the usefulness of this approach, continuous 3D hydrological simulations were conducted with different spatial resolutions in the highly instrumented Wüstebach catchment, Germany. Our results indicated that the introduction of an amplification factor can effectively improve model performances both in terms of soil moisture and runoff simulation. However, comparing simulated soil moisture pattern with observation indicated that uniform application of an amplification factor can lead to local overcorrection of soil hydraulic conductivity. This problem could be circumvented by applying the amplification factor only to model grid cells that suffer from high information loss. To this end, we tested two schemes to define appropriate location-specific correction factors. Both schemes led to improved model performance both in terms of soil water content and runoff simulation. Thus, we anticipate that our proposed scaling approach is useful for the application of next-generation hyper-resolution global land surface models.

  12. Ecosystem Services Derived from Headwater Catchments

    EPA Science Inventory

    We used data from the USEPA’s wadeable streams assessment (WSA), US Forest Service’s forest inventory and analysis (FIA), and select USFS experimental forests (EF) to investigate potential ecosystems services derived from headwater catchments. C, N, and P inputs to these catchmen...

  13. Global investigation of vegetation impact on mean annual catchment evapotranspiration

    NASA Astrophysics Data System (ADS)

    Peel, Murray C.; McMahon, Thomas A.; Finlayson, Brian L.

    2010-05-01

    Historically, relationships between catchment vegetation type, evapotranspiration and runoff have been assessed primarily through paired catchment studies. The literature contains results from over 200 of these studies from around the world but two factors limit the applicability of the results to the wider domain. Firstly, catchment areas are generally small (<10 km2). Secondly, the range of climate types is narrow, with temperate (Köppen C) and cold (Köppen D) climate types in the majority. Here we present results from a global assessment of the impact of vegetation type on mean annual catchment evapotranspiration for a large, spatially and climatically diverse dataset of 699 catchments. This assessment is based on analysis of areal precipitation, temperature, runoff, and land cover information from each catchment, which differs from the paired catchment methodology where streamflow responses to a controlled land cover change are assessed. When catchments are grouped by vegetation type, any evidence of differing vegetation impact on actual evapotranspiration will be observed through differences in mean annual actual evapotranspiration, defined as precipitation minus runoff. Stratifying catchments by climate type was observed to be important when assessing the vegetation impact on evapotranspiration. Tropical and temperate forested catchments had significantly higher median evapotranspiration (~170mm and ~130mm, respectively) than non-forested catchments. Cold forested catchments unexpectedly had significantly lower median evapotranspiration (~90mm) than non-forested catchments. No significant difference in median evapotranspiration was found between temperate evergreen and deciduous forested catchments, though sample sizes were small. Temperate evergreen needleleaf forested catchments had significantly higher median evapotranspiration than evergreen broadleaf forested catchments, though again sample sizes were small. The significant difference in median

  14. Transformations of DOM in forested catchments: the pathways of DOM from litter and soil to river export

    NASA Astrophysics Data System (ADS)

    Lajtha, K.; Yano, Y.; Crow, S.; Kaushal, S.

    2006-12-01

    Although the quality and quantity of DOM ultimately derives from plant detritus and soils in watersheds, three is substantial alteration of DOM as it passes from litter through the terrestrial landscape. As DOM is generated from plant and microbial detritus and processing, different fractions may be lost via respiration, form quasi-stable soil organic matter, or be temporarily sorbed to soil minerals. We followed the fate of DOC and DON from forested plots with experimentally altered detritus loads to determine the relative roles of original plant litter chemistry and soil transformations. Our study site was the DIRT (Detrital Input and Removal Treatment) plots at the H.J. Andrews Experimental Forest in Oregon, where treatments include detrital additions (wood vs. needle litter), litter exclusion, and root exclusions. Fractionation of detritus leachate solutions demonstrated significant differences in DOC chemistry from different detrital sources. Root leachates produced high quantities of hydrophilic neutral DOC, a fraction rich in labile sugars and polysaccharides; young wood extracts produced higher quantities of weak hydrophobic acids and hydrophobic neutrals (longer chain hydrocarbons); older wood had lower quantities of most labile constituents but was rich in strong hydrophobic acids. Although laboratory extracts of different litter types showed differences in DOM chemistry, soil solutions collected just below the forest floor from the differing detrital treatments were remarkably uniform and poor in labile constituents, suggesting microbial equalization of DOM leachate in the field. DOM quality and concentrations changed significantly with passage through soil profiles. DOC concentrations decreased through the soil profile in all plots to a greater degree than did dissolved organic nitrogen (DON), most likely due to preferential sorption of high C:N hydrophobic dissolved organic matter (DOM) in upper horizons. Percent hydrophobic DOM decreased significantly

  15. Characteristics of the water and dissolved matter circulation in the young-glacial catchment of the Czechowskie lake (Tuchola Pinewood Forest, Poland)

    NASA Astrophysics Data System (ADS)

    Brykala, Dariusz; Gierszewski, Piotr; Kaszubski, Michal

    2014-05-01

    The studies on the conditions of the water and dissolved matter circulation in the young-glacial catchment of the Czechowskie lake (Tuchola Pinewood Forest) have been conducted since 2012. They are implemented on the basis of an organised network monitoring surface water and groundwater. An important aim of the study is to assess the impact of both modern and fossil lakes on the regime of the outflow and the transformation of the water chemical properties. A high stability of the first groundwater table was recorded. During the study period the range of the groundwater level ranged from 0.17 to 0.92 m. In comparison with the small fluctuations in the groundwater level within the sandy outwash areas, a relatively high instability was shown by the shallow waters of the lake terraces. The measurements of the discharge showed that its average value at the outflow from the Czechowskie lake is 30 dm3s-1. It almost equals the total amount of water flowing into the lake through watercourses. The average specific runoff from the basin of the Czechowskie lake was 3 dm3s-1km-2. The total water mineralisation expressed as the sum of the ions is in the range from 70 to 750 mg dm-3. Both surface water, i.e. the water in streams and lakes, and underground water from different depths represent the bicarbonate-calcium-sulphate type characteristic of the young- glacial environment. The results of hydrochemical mapping and the analysis of the ionic composition of the water showed large spatial variability of the physico-chemical properties of the tested waters and, at the same time, high stability of their ionic composition. At the present stage of the research it is possible to identify the water enrichment zones in salts, which are basins of paleolakes filled with the organic-carbonate sediment, and the zones of salt precipitation within the contemporary lakes. The situation described above creates a specific, cascade model of the transformation of chemical properties of water

  16. Relationships Between Long-term Atmospheric Wet Deposition and Stream Chemistry in Mid-Appalachian Forest Catchments

    NASA Astrophysics Data System (ADS)

    DeWalle, D. R.; Boyer, E. W.; Buda, A. R.

    2014-12-01

    Improved understanding of the link between atmospheric deposition and surface water quality is critical to assessing the degree to which forested watersheds have recovered from acidification. This presentation draws upon long-term (1982-2013) atmospheric wet deposition and stream chemistry time series to study how changes in atmospheric chemical inputs have been propagated to stream waters. We used autocorrelation and lagged cross-correlation techniques to analyze monthly time series describing variations of chloride, sulfate and inorganic nitrogen concentrations for four pairs of stream/deposition monitoring sites. Autocorrelation analysis revealed that individual atmospheric input time series of sulfate and inorganic nitrogen were strongly seasonal, while chloride inputs exhibited little seasonality. Stream chemistry time series exhibited gradually declining autocorrelation trends with increasing lag times suggesting that atmospheric input signals were variably damped by the forest ecosystems . Lagged cross-correlation between raw atmospheric and stream chemistry time series indicated gradual decreases in correlation within superimposed regular annual cycles of correlation over 10- 15 years of lag time. Pre-whitening of each atmospheric and stream time series using regression or ARIMA models removed the influence of long-term trends, seasonal cycles and other factors and revealed occurrence of relatively few and highly variable lag times with significant correlations. While lagged cross-correlation of raw time series data provided some useful insights into the long-term trend and seasonal nature of the linkages between atmospheric deposition and stream chemistry, cross-correlation of shorter-term residual variations after prewhitening did not produce a consistent pattern of lag times with significant correlations in our monthly time series data.

  17. Understanding uncertainties when inferring mean transit times of water trough tracer-based lumped-parameter models in Andean tropical montane cloud forest catchments

    NASA Astrophysics Data System (ADS)

    Timbe, E.; Windhorst, D.; Crespo, P.; Frede, H.-G.; Feyen, J.; Breuer, L.

    2014-04-01

    Weekly samples from surface waters, springs, soil water and rainfall were collected in a 76.9 km2 mountain rain forest catchment and its tributaries in southern Ecuador. Time series of the stable water isotopes δ18O and δ2H were used to calculate mean transit times (MTTs) and the transit time distribution functions (TTDs) solving the convolution method for seven lumped-parameter models. For each model setup, the generalized likelihood uncertainty estimation (GLUE) methodology was applied to find the best predictions, behavioral solutions and parameter identifiability. For the study basin, TTDs based on model types such as the linear-piston flow for soil waters and the exponential-piston flow for surface waters and springs performed better than more versatile equations such as the gamma and the two parallel linear reservoirs. Notwithstanding both approaches yielded a better goodness of fit for most sites, but with considerable larger uncertainty shown by GLUE. Among the tested models, corresponding results were obtained for soil waters with short MTTs (ranging from 2 to 9 weeks). For waters with longer MTTs differences were found, suggesting that for those cases the MTT should be based at least on an intercomparison of several models. Under dominant baseflow conditions long MTTs for stream water ≥ 2 yr were detected, a phenomenon also observed for shallow springs. Short MTTs for water in the top soil layer indicate a rapid exchange of surface waters with deeper soil horizons. Differences in travel times between soils suggest that there is evidence of a land use effect on flow generation.

  18. Comparison of sap flux data from two instrumented tree species in a forested catchment with different levels of water stress

    NASA Astrophysics Data System (ADS)

    Hartsough, P. C.; Roudneva, E.; Malazian, A. I.; Meadows, M. W.; Kelly, A. E.; Bales, R. C.; Goulden, M.; Hopmans, J. W.

    2011-12-01

    Two trees were instrumented with heat pulse sapflux sensors in the Southern Sierra Critical Zone Observatory (SSCZO) within the Kings River Experimental Watershed (KREW) to better understand transpiration as it relates to water availability from deeper sources. At the first instrumented site, CZT-1, a White Fir (Abies concolor) was instrumented on a flat ridge with access to deep soil moisture. Extensive monitoring of shallow and deep soil regions confirm that there is significant soil water available from 100-400cm as the tree exhausts water from shallower depths. A root excavation of an adjacent tree shows the roots distributed from 30-150cm with limited roots available to access deeper soil water and water stored in the saprolite. At the second instrumented site, CZT-2, a Ponderosa Pine (Pinus Ponderosa) was instrumented with a similar suite of sap flow and soil sensors. The CZT-2 site is on a slight slope and is characterized by shallow soils (<90cm) with extensive cobbles and bedrock outcrops with limited access to deeper soil or saprolite water. The second site also sits in the open while the first site is more protected in a closed forest. The two sites show different responses to changes in rain and snow loading from above as well as soil drainage and water depletion from below. They also have different thresholds for transpiration shut down both due to late season water deficit and also during winter periods where air temperatures are high enough to permit photosynthesis. Sap flux data are supplemented by extensive soil water content and potential measurements around both trees as well as evapotranspiration measurements from a 50m flux tower located between the two instrumented trees.

  19. Disinfection of Bacillus spores with acidified nitrite.

    PubMed

    Szabo, Jeffrey G; Adcock, Noreen J; Rice, Eugene W

    2014-10-01

    Disinfecting water generated from a bioterrorism contamination event will require large amounts of disinfectant since the volume of water flushed from a drinking water distribution system or wash water collected from a contaminated outdoor area can accumulate quickly. Commonly used disinfectants may be unavailable in the necessary amounts, so evaluation of alternative disinfectants is needed. This study focuses on disinfection of Bacillus spores in water using acidified nitrite. The effect of varying pH (2 or 3), temperature (5°C or 24°C), nitrite concentration (0.01 or 0.1M), buffer (Butterfields or Phosphate Buffered Saline, PBS) and Bacillus species (B. globigii and B. anthracis Sterne) was evaluated. B. globigii was more resistant to disinfection under all water quality conditions. Disinfection was more effective for B. globigii and B. anthracis Sterne at 0.1M nitrite, pH 2, and 24°C. Disinfection of B. anthracis Sterne was enhanced in low ionic strength Butterfields buffer compared to PBS. PMID:25065806

  20. Evaluation of High-Temporal-Resolution Bedload Sensors for Tracking Channel Bed Movement and Transport Thresholds in Forested Mountain Headwater Catchments.

    NASA Astrophysics Data System (ADS)

    Martin, S.; Conklin, M. H.; Bales, R. C.

    2014-12-01

    High temporal resolution data is required to take channel bed movement data beyond time integrated changes between measurements where many of the subtleties of bedload movement patterns are often missed. This study used continuous bedload scour sensors (flexible, fluid-filled pans connected to a pressure transducer) to collect high temporal resolution, long term bedload movement data for 4 high elevation (1500-1800 m) Sierra Nevada headwater streams draining 1 km2 catchments and to investigate the physical channel characteristics under which they perform best. Data collected by the scour sensors were used to investigate the disturbance and recovery patterns of these streams, to relate the observed patterns to channel bed stability, and to evaluate whether the channel bed is acting as a sediment source, sink, or storage across various temporal scales. Finally, attempts are made to identify discharge thresholds for bed movement from scour sensor and discharge data and to compare these threshold values to observed changes in the channel bed. Bedload scour data, turbidity data, and stream discharge data were collected at 15 minute intervals for (WY 2011 to WY 2014), including both above average (2011) and below average (2012, 2013, 2014) water years. Bedload scour sensors were found to have a relatively high (60%) failure rate in these systems. In addition, they required in situ calibrations as the factory and laboratory calibrations did not translate well to the field deployments. Data from the working sensors, showed patterns of abrupt channel bed disturbance (scour and/or fill) on an hour to day temporal scale followed by gradual recovery on a day to month scale back to a stable equilibrium bed surface elevation. These observed patterns suggest the bed acts as a short term source or sink for sediment, but is roughly sediment neutral over longer time periods implying the changes in bed elevation are reflective of fluctuations in storage rather than a true source or

  1. Late Pleistocene to early Holocene aeolian and flash-flood sedimentation and soil formation in a small hilly catchment in SW-Germany (Palatinate forest)

    NASA Astrophysics Data System (ADS)

    Dotterweich, M.; Kühn, P.; Tolksdorf, J. F.; Müller, S.; Nelle, O.

    2012-04-01

    This paper focuses on the dynamics of sedimentation processes and soil development in a steep slope 0-order catchment in the sandy Lower Bunter of the south-western mid-range mountains in Germany during the transition period from the late Glacial to the early Holocene. Italso discusses how late Palaeolithic gatherers and hunters may have influenced these processes by sedentary land occupation. The investigated dry valley covers an area of around 16.6 ha and is characterized by short and steep slopes of 30° to 60°. A significant amount of the sediments from the adjacent slopes had been captured along the wide and rather flat valley bottom and at the small outlet. Several exposures, pits, and percussion liner drillings revealed a weak to highly weathered reddish sandy material at the base and eight subsequent layers of incoherent sandy and charcoal (from pines) enriched sediments with different colours ranging from olive-brown to dull reddish brown. By stratigraphical means, the lowermost sediment can be ascribed to the early Lateglacial when the deposition of aeolian sands under cold conditions with scarce vegetation cover was a widespread phenomenon. The subsequent layer contains a higher amount of silt and dates into the Allerød as suggested by radiocarbon dating. This is corroborated by the occurrence of LST that indicate that these sediments have been near to the surface around 12,900 yr BP. It shows characteristics of a palaeosol with Bwb and BwAhb horizons (Brunic Arenosols dystric) and with greyish Ahb and Eb horizons (Albic Arenosols dystric) similar to the Usselo/Finow soils in north-eastern Germany. In the material above, many remnants of roots and organic particles and rounded bone fragments were revealed by micromorphological analyses. Then, an alternation of reddish brown coarse to fine sands and small, partly rounded stones with some small intercalate aggregations of humic material rich in charcoal which dates to around 10,000 yr BP were deposited

  2. Temporal variation of transit time of rainfall-runoff water and groundwater flow dynamics inferred by noble gasses concentration (SF6, CFCs) in a forested small catchment (Fukushima, Japan)

    NASA Astrophysics Data System (ADS)

    Sakakibara, Koichi; Tsujimura, Maki; Onda, Yuichi; Iwagami, Sho; Konuma, Ryohei; Sato, Yutaro

    2016-04-01

    Time variant transit time of water in catchments can fundamentally describe catchment function, controlling rainfall-runoff generation, groundwater flow pathway and water storage. Though rainstorm event has been recognized as active phase on catchment hydrology, accurate and precise time variance of water transit time and related water dynamics during rainstorm have not been well clarified yet. Here, in order to reveal temporal variation of mean transit time of groundwater and related hydrological processes in a forested small catchment during rainstorm event, periodic and intensive field observations (15 - 17th July 2015, rainfall of 100.8 mm in total) were conducted in Yamakiya district (Fukushima, Japan) from September 2014 to December 2015. Discharge volume, groundwater table and precipitation amount were measured in 10 minutes interval. Water samples were taken from groundwater, discharge water, soil water and precipitation for determination of stable isotopic compositions (δ18O, δ2H), inorganic solutes concentration and dissolved noble gasses concentration (CFC11, CFC12, CFC113, SF6) in water. Storm hydrograph and groundwater table clearly responded to rainfall event especially with more than 30 mm per day throughout monitoring period. According to SF6 concentration in water, the mean transit time of discharge water (perennial spring) showed 3 - 6.5 years in the no-rainfall period (steady state), but fluctuated from zero to 12.5 years in the rainstorm event with totally 100.8 mm (unsteady state). The mean transit time of discharge water dramatically altered from zero to 12.5 years from before to after the tentative hydrograph peak in the rising limb, indicating new water components were dominant before tentative hydrograph peak, whereas deep groundwater component with longer residence time contributed much to discharge after the tentative hydrograph peak. On the other hand, mean residence time of groundwater (water in 5 m well) ranged from 0.5 to 11.5 years

  3. Growth and blood chemistry of ducklings reared on acidified wetlands

    USGS Publications Warehouse

    Rattner, B.A.; Haramis, G.; Linder, G.; Chu, D.

    1985-01-01

    Acid deposition is one factor that may be responsible for the decline of some waterfowl populations. Growth and physiological condition were monitored in captive-reared black ducks (Anas rubripes) exposed for 10-day trials (day 11-20 of life) on control (pH 6.8) and acidified (pH 5.0) man-made emergent wetlands. Impaired growth (body weight, culmen and tarsus length) and increased mortality (50%) were apparent in broods (hen + 4 ducklings) reared on acidified wetIands. Ducklings exbibiting poor growth had reduced hematocrit, plasma protein and cholesterol levels. This subset of birds had elevated plasma uric acid concentration and creatine kinase activity (perhaps due to enhanced protein and nucleotide catabolism). and elevated pIasma K+ levels. Based upon overt appearance, growth and blood chemistry, ducklings exposed to acidified wetlands were concluded to be in poorer condittion than those exposed on circumneutral pH wetlands.

  4. Stress Response of Salmonella enterica Serovar Typhimurium to Acidified Nitrite

    PubMed Central

    Mühlig, Anna; Behr, Jürgen; Scherer, Siegfried

    2014-01-01

    The antimicrobial action of the curing agent sodium nitrite (NaNO2), which is added as a preservative to raw meat products, depends on its conversion to nitric oxide and other reactive nitrogen species under acidic conditions. In this study, we used RNA sequencing to analyze the acidified-NaNO2 shock and adaptive responses of Salmonella enterica serovar Typhimurium, a frequent contaminant in raw meat, considering parameters relevant for the production of raw-cured sausages. Upon a 10-min exposure to 150 mg/liter NaNO2 in LB (pH 5.5) acidified with lactic acid, genes involved in nitrosative-stress protection, together with several other stress-related genes, were induced. In contrast, genes involved in translation, transcription, replication, and motility were downregulated. The induction of stress tolerance and the reduction of cell proliferation obviously promote survival under harsh acidified-NaNO2 stress. The subsequent adaptive response was characterized by upregulation of NsrR-regulated genes and iron uptake systems and by downregulation of genes involved in anaerobic respiratory pathways. Strikingly, amino acid decarboxylase systems, which contribute to acid tolerance, displayed increased transcript levels in response to acidified NaNO2. The induction of systems known to be involved in acid resistance indicates a nitrite-mediated increase in the level of acid stress. Deletion of cadA, which encodes lysine decarboxylase, resulted in increased sensitivity to acidified NaNO2. Intracellular pH measurements using a pH-sensitive green fluorescent protein (GFP) variant showed that the cytoplasmic pH of S. Typhimurium in LB medium (pH 5.5) is decreased upon the addition of NaNO2. This study provides the first evidence that intracellular acidification is an additional antibacterial mode of action of acidified NaNO2. PMID:25107963

  5. Considerations of acidifying water samples for 99Tc analysis.

    PubMed

    Blanchard, R L; Lieberman, R; Richardson, W S; Wakamo, C L

    1993-08-01

    Environmental water samples are routinely acidified before radionuclide analysis to prevent adsorption of radionuclides on the container walls. This study addresses the concern for volatilizing 99Tc from acid solutions during evaporation before beta analysis has been addressed. Water samples can be acidified to pH 1.7 with nitric acid and evaporated to dryness on planchets without significant losses of technetium due to volatilization. However, the planchets should not be flamed unless a detergent is used, and control samples should be flamed to determine the loss of activity under the conditions used. PMID:8392504

  6. Inter-comparison of three distributed hydrological models with respect to seasonal variability of soil moisture patterns at a small forested catchment.

    NASA Astrophysics Data System (ADS)

    Koch, Julian; Cornelissen, Thomas; Fang, Zhufeng; Bogena, Heye; Diekkrüger, Bernd; Kollet, Stefan; Stisen, Simon

    2016-04-01

    The objective of this study is to inter-compare three spatially distributed hydrological models (HydroGeoSphere, MIKE SHE and ParFlow-CLM) by means of their ability to simulate soil moisture patterns. This study pools the catchment modelling efforts which have been undertaken at the Wüstebach catchment; one of TERENO's hydrological observatories. The catchment is densely instrumented with a wireless sensor network (SoilNET) which allows continuous measurements of the spatio-temporal soil moisture dynamics. This unique dataset is ideal to benchmark hydrological models as it poses distinct challenges like seasonality and spatial heterogeneity. Two scenarios of soil parametrization assess the modelling implications of moving from homogeneous to heterogeneous porosity. The three given models perform well in terms of discharge and accumulated water balance components. However, their ability to predict soil moisture is found to be more diverging. Interpretations are ambiguous and depend on what performance metric and what level of spatial aggregation is chosen. In comparison to the other models, ParFlow-CLM performs more accurate at predicting the temporal dynamics and the heterogeneity aggregated to catchment scale. Nevertheless, at local scale HydroGeoSphere and MIKE SHE provide more detailed soil moisture predictions. Overall, a clear increase in performance can be attested to the scenario that includes heterogeneous porosity. Next to soil parametrization, topography is among the main drivers of soil moisture variability which was found to have an overemphasized feedback in ParFlow-CLM compared to the other models. This study stresses that further efforts toward spatially distributed input data need to emerge alongside a more suitable soil parametrization that can account for the observed heterogeneity and seasonality of soil moisture.

  7. Inter-comparison of three distributed hydrological models with respect to seasonal variability of soil moisture patterns at a small forested catchment

    NASA Astrophysics Data System (ADS)

    Koch, Julian; Cornelissen, Thomas; Fang, Zhufeng; Bogena, Heye; Diekkrüger, Bernd; Kollet, Stefan; Stisen, Simon

    2016-02-01

    The objective of this study is to inter-compare three spatially distributed hydrological models (HydroGeoSphere, MIKE SHE and ParFlow-CLM) by means of their ability to simulate soil moisture patterns. This study pools the catchment modeling efforts which have been undertaken at the Wüstebach catchment; one of TERENO's hydrological observatories. The catchment is densely instrumented with a wireless sensor network (SoilNET) which allows continuous measurements of the spatio-temporal soil moisture dynamics. This unique dataset is ideal to benchmark hydrological models as it poses distinct challenges like seasonality and spatial heterogeneity. Two scenarios of soil parametrization assess the modeling implications of moving from homogeneous to heterogeneous porosity. The three given models perform well in terms of discharge and accumulated water balance components. However, their ability to predict soil moisture is found to be more diverging. Interpretations are ambiguous and depend on what performance metric and what level of spatial aggregation is chosen. In comparison to the other models, ParFlow-CLM performs more accurate at predicting the temporal dynamics and the heterogeneity aggregated to catchment scale. Nevertheless, at local scale HydroGeoSphere and MIKE SHE provide more detailed soil moisture predictions. Overall, a clear increase in performance can be attested to the scenario that includes heterogeneous porosity. Next to soil parametrization, topography is among the main drivers of soil moisture variability which was found to have an overemphasized feedback in ParFlow-CLM compared to the other models. This study stresses that further efforts toward spatially distributed input data need to emerge alongside a more suitable soil parametrization that can account for the observed heterogeneity and seasonality of soil moisture.

  8. Use of Linear Models for Thermal Processing Acidified Foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acidified vegetable products with a pH above 3.3 must be pasteurized to assure the destruction of acid resistant pathogenic bacteria. The times and temperatures needed to assure a five log reduction by pasteurization have previously been determined using a non-linear (Weibull) model. Recently, the F...

  9. Transfer of 137Cs and 134Cs from litter into soil's of Japanese cypress forest after Fukushima nuclear accident in Karasawayama catchment, Tochigi prefecture

    NASA Astrophysics Data System (ADS)

    Mengistu, T. T.; Onda, Y.; Kato, H.; Gomi, T.

    2011-12-01

    The mega earthquake that rampaged north-east Japan on March 11, 2011 and the triggered subsequent tsunami hit the Fukushima Daiichi Nuclear power plant and resulted the discharge of about 770,000 terabecquerel radionuclide materials to the atmosphere. The distribution and deposition of the radionucides are then governed by the wind and rain following the release. When the cloud of radionuclide material by-pass the forest ecosystem (as radiodust-sinker), radionuclides are trapped and deposited to the forest floor through dry, litter, wet depositions. Litter-fall, as a key process of nutrient cycling in forest ecosystem, plays a great role in transferring canopy-trapped radionuclides to the forest soil. And so, we are monitoring the of Fukushima derived 137Cs deposition rate through litter to forest soil's of Japanese cypress(Chamaecyparis obutsa Sieb.et Zucc.) forests located approximately 160 km from the crippled nuclear power plant. For this purpose, five litter traps (1m2 areas each) were set up at one meter above the ground in the forest stand at the end of March 2011. Fukushima-derived 137Cs is then estimated from 134Cs:137Cs ratio as all 134Cs is originated from Fukushima. Within the two months of the accident, mean 134Cs:137Cs ratio was 0.8 in cypress litter. The inventories of both 137Cs and 134Cs in the upper 2cm forest soil were found 5089 Bq m-2 and 3571 Bq m-2, respectively. As a result, the amount of Fukushima-derived 137Cs deposition in upper 2cm soil layer by cypress litter is 4464 Bq m-2. This value account 88% of the total inventories of 137Cs in the upper 2cm soils and the other depositional paths (dry and wet fall) including old 137Cs cover only 12%. The transfer rate of 137Cs and 134Cs from canopy-litter to soil could be depend on litter's radionuclide adsorption strength (canopy and leaves architecture), the rate, amount of litter fall and its residence time in the canopy and forest floor. However, the results strongly confirmed that litter is

  10. The impact of integrating WorldView-2 sensor and environmental variables in estimating plantation forest species aboveground biomass and carbon stocks in uMgeni Catchment, South Africa

    NASA Astrophysics Data System (ADS)

    Dube, Timothy; Mutanga, Onisimo

    2016-09-01

    Reliable and accurate mapping and extraction of key forest indicators of ecosystem development and health, such as aboveground biomass (AGB) and aboveground carbon stocks (AGCS) is critical in understanding forests contribution to the local, regional and global carbon cycle. This information is critical in assessing forest contribution towards ecosystem functioning and services, as well as their conservation status. This work aimed at assessing the applicability of the high resolution 8-band WorldView-2 multispectral dataset together with environmental variables in quantifying AGB and aboveground carbon stocks for three forest plantation species i.e. Eucalyptus dunii (ED), Eucalyptus grandis (EG) and Pinus taeda (PT) in uMgeni Catchment, South Africa. Specifically, the strength of the Worldview-2 sensor in terms of its improved imaging agilities is examined as an independent dataset and in conjunction with selected environmental variables. The results have demonstrated that the integration of high resolution 8-band Worldview-2 multispectral data with environmental variables provide improved AGB and AGCS estimates, when compared to the use of spectral data as an independent dataset. The use of integrated datasets yielded a high R2 value of 0.88 and RMSEs of 10.05 t ha-1 and 5.03 t C ha-1 for E. dunii AGB and carbon stocks; whereas the use of spectral data as an independent dataset yielded slightly weaker results, producing an R2 value of 0.73 and an RMSE of 18.57 t ha-1 and 09.29 t C ha-1. Similarly, high accurate results (R2 value of 0.73 and RMSE values of 27.30 t ha-1 and 13.65 t C ha-1) were observed from the estimation of inter-species AGB and carbon stocks. Overall, the findings of this work have shown that the integration of new generation multispectral datasets with environmental variables provide a robust toolset required for the accurate and reliable retrieval of forest aboveground biomass and carbon stocks in densely forested terrestrial ecosystems.

  11. Thermophilic treatment of acidified and partially acidified wastewater using an anaerobic submerged MBR: Factors affecting long-term operational flux.

    PubMed

    Jeison, D; van Lier, J B

    2007-09-01

    The long-term operation of two thermophilic anaerobic submerged membrane bioreactors (AnSMBRs) was studied using acidified and partially acidified synthetic wastewaters. In both reactors, cake formation was identified as the key factor governing critical flux. Even though cake formation was observed to be mostly reversible, particle deposition proceeds fast once the critical flux is exceeded. Very little irreversible fouling was observed during long-term operation, irrespective of the substrate. Critical flux values at the end of the reactors operation were 7 and 3L/m(2)h for the AnSMBRs fed with acidified and partially acidified wastewaters, respectively, at a gas superficial velocity of 70m/h. Small particle size was identified as the responsible parameter for the low observed critical flux values. The degree of wastewater acidification significantly affected the physical properties of the sludge, determining the attainable flux. Based on the fluxes observed in this research, the membrane costs would be in the range of 0.5euro/m(3) of treated wastewater. Gas sparging was ineffective in increasing the critical flux values. However, preliminary tests showed that cross-flow operation may be a feasible alternative to reduce particle deposition. PMID:17644148

  12. Runoff generation mechanism at two distinct headwater catchments - isotopic evidence

    NASA Astrophysics Data System (ADS)

    Dohnal, Michal; Votrubová, Jana; Šanda, Martin; Tesař, Miroslav; Vogel, Tomáš; Dušek, Jaromír

    2016-04-01

    Data from two headwater catchments indicate considerably different runoff formation mechanisms. The contributions of different surface and subsurface runoff mechanisms to the catchment discharge formation at these two small forested headwater catchments are studied with help of the natural isotopic signatures of the observed fluxes. The Uhlirska catchment (1.78 sq. km, Jizera Mts., Czech Republic) is situated in headwater area of Cerna Nisa stream. Deluviofluvial granitic sediments in the valley bottom areas (riparian zones/wetlands) are surrounded by gentle hillslopes with shallow soils developed on crystalline bedrock. The Liz catchment (0.99 sq. km, Bohemian Forest, Czech Republic) belongs to hillslope-type catchments without riparian zones situated in headwater area of Volynka River. The soil at Liz is developed on biotite paragneiss bedrock. Autocorrelation analysis of the measured catchment discharge rates reveals different hydrograph characteristics for each of the two catchments. Estimated autocorrelation lengths differ by an order of magnitude. Variations of oxygen-18 isotope concentrations in precipitation, groundwater and streamflow were analyzed. Several significant rainfall-runoff events at each of the two catchments were analyzed in detail. These events exhibit substantial difference in isotopic compositions of event and pre-event water, which facilitates hydrograph separation. Clockwise and counterclockwise hysteretic relationships between the stream discharge and its isotope concentration were identified. Results were confronted with the previously published concepts of the runoff formation at the catchments under study. The research was funded by the Czech Science Foundation, project No. 14-15201J.

  13. Changes in runoff generation due to conversion of catchment vegetation

    NASA Astrophysics Data System (ADS)

    Vilhar, Urša; Kestnar, Klemen; Šraj, Mojca

    2015-04-01

    In Central Europe, many pure Norway spruce stands, established on primary beech sites, were converted into mixed stands over the last 60 years. The conversion of forest management from Norway spruce monocultures into mixed deciduous-coniferous forests changed the forest structure dramatically. This changes could influence the hydrological processes on the catchment scale, associated with changes in runoff generation. In this study, the effect of forest management on the runoff in mixed deciduous-coniferous stands on Pohorje mountains in NE Slovenia were investigated. Two small forested experimental catchments of Oplotnica River on Pohorje were compared with similar size and shape but different share of Norway spruce Picea abies (L. Karst) and European beech Fagus sylvatica (L.). Measured stream flows, throughfall, stemflow and the mixture of forests were compared in the period 2008 till 2013 for both catchments. Hydrological models in the HEC-HMS program were built for both catchmenta, calibrated and validated using measured data. Precipitation losses were estimated by the Soil Conservation Service (SCS) method, while precipitation was converted into surface runoff using the SCS synthetic unit hydrograph procedure. The measured seasonal throughfall and stream flow was lower in the catchment with higher share of spruce in the mixed spruce-beech forest. Modeled precipitation losses in the river basins were 92% and 95% of total precipitation, respectively. The results indicate higher interception, infiltration and accumulation of precipitation in the catchment with higher share of spruce in the mixed spruce-beech forest. Forest management practices should aim towards decreased surface runoff in alpine catchments. Therefore implementation of hydrology-oriented sylvicultural measures via a more accurate prediction of the impacts of tree species conversion on runoff generation in this type of alpine catchments is discussed.

  14. Acidified Litter Benefits the Intestinal Flora Balance of Broiler Chickens

    PubMed Central

    Garrido, Margarita Novoa; Skjervheim, Magne; Oppegaard, Hanne; Sørum, Henning

    2004-01-01

    The alterations in the balance of the normal intestinal bacterial flora of chickens exposed to acidified wood-derived litter were analyzed and compared to those of a control group exposed to nonacidified litter. A total of 1,728 broilers were divided into two groups, with six replicates in each. One group was exposed to dry wood-derived litter, and the other was exposed to dry wood-derived litter sprayed with a mixture of sodium lignosulfonate, formic acid, and propionic acid. At five different times, five chickens from each pen were killed and the intestinal contents from ileum and caeca were collected. The samples were diluted and plated onto selective media to identify coliforms, Lactobacillus spp., Clostridium perfringens, and Enterococcus spp. Covariance analysis of bacterial counts showed significantly lower counts for C. perfringens in the caeca and the ileum and for Enterococcus spp. and Lactobacillus spp. in the ileum in chickens exposed to the acidified litter. Lactobacillus spp. showed significantly higher counts in the caeca in chickens exposed to acidified litter. There was no difference between the two litters with regard to coliforms in the ileum and the caeca or to Enterococcus spp. in the caeca. The study shows that exposing the chickens to acidified litter lowers the intestinal bacterial number, especially in the ileum, without negative consequences for the chicken's health or performance. Of special interest are the lower counts of C. perfringens and Enterococcus spp. that might reduce the risk of developing clinical or subclinical necrotic enteritis and growth depression. PMID:15345401

  15. Does road salting confound the recovery of the microcrustacean community in an acidified lake?

    PubMed

    Jensen, Thomas Correll; Meland, Sondre; Schartau, Ann Kristin; Walseng, Bjørn

    2014-04-15

    Numerous boreal lakes across the Northern Hemisphere recovering from acidification are experiencing a simultaneous increase in chloride (Cl) concentrations from road salting. Increasing Cl may have profound effects on the lake ecosystem. We examine if an increase in Cl from road salting has modified the recovery of the microcrustacean community in an acidified boreal lake undergoing chemical recovery (study lake). Results from the study lake were compared with an acidified "reference lake". The community changed during the study period in the study lake mainly driven by the reduction in acidification pressure. Despite the community changes and an increase in species richness, the absence of several acid sensitive species, previously occurring in the lake, indicates a delayed biological recovery relative to the chemical recovery. Moreover, changes in occurrence of acid sensitive and acid tolerant species indicated that the biological recovery was slower in the study lake compared to the "reference". Although recurrent episodes of high aluminum and low pH and decreasing Ca are likely important factors for the delay, these do not explain, for instance, the shift from Cyclops scutifer to Bosmina longispina in the study lake. Although the contribution of Cl was not significant, the correlation between Cl and the variation in microcrustacean community was twice as high in the study lake compared to the "reference". We argue that small, sheltered forest lakes may be especially sensitive to increased Cl levels, through changes in pattern of stratification, thus providing a mechanism for the shift from C. scutifer to B. longispina. The reduction of the acidification pressure seems to override the Cl effects on microcrustaceans at low Cl levels in salt-affected lakes recovering from acidification. However, prognoses for growing traffic and increasing road salting raise concern for many recovering lakes located in proximity to roads and urbanized areas. PMID:24530583

  16. Effect of the Resolution and Accuracy of DTM produced with Aerial Photogrammetry and Terrestrial Laser Scanning on Slope- and Catchment-scale Erosion Assessment in a Recently Burnt Forest Area: a Case Study

    NASA Astrophysics Data System (ADS)

    Cambra, Sílvia; Pereira, Luísa; Keizer, Jan Jacob

    2010-05-01

    Wildfires are a common phenomenon in Portugal, affecting on average 100.000 ha of rural areas per year and up to 400.000 ha in dramatic years like 2003 and 2005. Wildfires can strongly enhance the hydrological response and associated sediment losses in recently burnt forest catchments and, thereby, negatively affect land-use sustainability of the affected terrains as well as ecosystem functioning of downstream aquatic habitats. Therefore, the EROSFIRE-I and -II projects aim at developing a GIS-tool for predicting soil erosion hazard following wildfire and, ultimately, for assessing the implications of alternative post-fire land management practices. Assessment of runoff and soil erosion rates critically depends on accurate estimates of the corresponding runoff areas. In the case of catchments as well as unbounded erosion plots (arguably, the only practical solution for slope-scale measurements), delineation of runoff area requires a Digital Terrain Model (DTM) with an adequate resolution and accuracy. The DTM that was available for the Colmeal study area, localized in the mountain range of Lousã, in the central part of Portugal, of EROSFIRE-II project is that of the 1:25.000 topographic map produced by the Military Geographic Institute. Since the Colmeal area involves a rather small experimental catchment of roughly 10 ha and relatively short study slopes of less than 100 m long, two different data acquisition techniques were used to produce high-resolution and high-accuracy DTM. One of the data acquisition techniques is aerial photogrammetry whilst the other is terrestrial laser scanning. In order to produce a DTM by photogrammetric means, a dedicated digital aerial photography mission was carried out. The images have a pixel size of 10 cm. Manual measurements permitted to measure breaklines and were complemented by automatic measurements. In this way, a DTM in a TIN format was produced. This was further converted to grid format using the ArcGIS software system

  17. Catchment scale afforestation for mitigating flooding

    NASA Astrophysics Data System (ADS)

    Barnes, Mhari; Quinn, Paul; Bathurst, James; Birkinshaw, Stephen

    2016-04-01

    After the 2013-14 floods in the UK there were calls to 'forest the uplands' as a solution to reducing flood risk across the nation. At present, 1 in 6 homes in Britain are at risk of flooding and current EU legislation demands a sustainable, 'nature-based solution'. However, the role of forests as a natural flood management technique remains highly controversial, due to a distinct lack of robust evidence into its effectiveness in reducing flood risk during extreme events. SHETRAN, physically-based spatially-distributed hydrological models of the Irthing catchment and Wark forest sub-catchments (northern England) have been developed in order to test the hypothesis of the effect trees have on flood magnitude. The advanced physically-based models have been designed to model scale-related responses from 1, through 10, to 100km2, a first study of the extent to which afforestation and woody debris runoff attenuation features (RAFs) may help to mitigate floods at the full catchment scale (100-1000 km2) and on a national basis. Furthermore, there is a need to analyse the extent to which land management practices, and the installation of nature-based RAFs, such as woody debris dams, in headwater catchments can attenuate flood-wave movement, and potentially reduce downstream flood risk. The impacts of riparian planting and the benefits of adding large woody debris of several designs and on differing sizes of channels has also been simulated using advanced hydrodynamic (HiPIMS) and hydrological modelling (SHETRAN). With the aim of determining the effect forestry may have on flood frequency, 1000 years of generated rainfall data representative of current conditions has been used to determine the difference between current land-cover, different distributions of forest cover and the defining scenarios - complete forest removal and complete afforestation of the catchment. The simulations show the percentage of forestry required to have a significant impact on mitigating

  18. Spatio-temporal validation of long-term 3D hydrological simulations of a forested catchment using empirical orthogonal functions and wavelet coherence analysis

    NASA Astrophysics Data System (ADS)

    Fang, Zhufeng; Bogena, Heye; Kollet, Stefan; Koch, Julian; Vereecken, Harry

    2015-10-01

    Soil moisture plays a key role in the water and energy balance in soil, vegetation and atmosphere systems. According to Wood et al. (2011) there is a grand need to increase global-scale hyper-resolution water-energy-biogeochemistry land surface modelling capabilities. These modelling capabilities should also recognize epistemic uncertainties, as well as the nonlinearity and hysteresis in its dynamics. Unfortunately, it is not clear how to parameterize hydrological processes as a function of scale, and how to test deterministic models with regard to epistemic uncertainties. In this study, high resolution long-term simulations were conducted in the highly instrumented TERENO hydrological observatory of the Wüstebach catchment. Soil hydraulic parameters were derived using inverse modelling with the Hydrus-1D model using the global optimization scheme SCE-UA and soil moisture data from a wireless soil moisture sensor network. The estimated parameters were then used for 3D simulations of water transport using the integrated parallel simulation platform ParFlow-CLM. The simulated soil moisture dynamics, as well as evapotranspiration (ET) and runoff, were compared with long-term field observations to illustrate how well the model was able to reproduce the water budget dynamics. We investigated different anisotropies of hydraulic conductivity to analyze how fast lateral flow processes above the underlying bedrock affect the simulation results. For a detail investigation of the model results we applied the empirical orthogonal function (EOF) and wavelet coherence methods. The EOF analysis of temporal-spatial patterns of simulated and observed soil moisture revealed that introduction of heterogeneity in the soil porosity effectively improves estimates of soil moisture patterns. Our wavelet coherence analysis indicates that wet and dry seasons have significant effect on temporal correlation between observed and simulated soil moisture and ET. Our study demonstrates the

  19. Study of Spectral Modifications in Acidified Ignitable Liquids by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy.

    PubMed

    Martín-Alberca, Carlos; Ojeda, Fernando Ernesto Ortega; García-Ruiz, Carmen

    2016-03-01

    In this work, the spectral characteristics of two types of acidified gasoline and acidified diesel fuel are discussed. Neat and acidified ignitable liquids (ILs) infrared absorption spectra obtained by attenuated total reflection Fourier transform infrared spectroscopy were compared in order to identify the modifications produced by the reaction of the ILs with sulfuric acid. Several bands crucial for gasoline identification were modified, and new bands appeared over the reaction time. In the case of acidified diesel fuel, no significant modifications were observed. Additionally, the neat and acidified ILs spectra were used to perform a principal components analysis in order to confirm objectively the results. The complete discrimination among samples was successfully achieved, including the complete differentiation among gasoline types. Taking into account the results obtained in this work, it is possible to propose spectral fingerprints for the identification of non-burned acidified ILs in forensic investigations related with arson or the use of improvised incendiary devices (IIDs). PMID:26810182

  20. Anaerobic digestion of acidified slurry fractions derived from different solid-liquid separation methods.

    PubMed

    Sutaryo, Sutaryo; Ward, Alastair James; Møller, Henrik Bjarne

    2013-02-01

    Batch assays investigating the ultimate methane yields (B(0)) of acidified slurry fractions produced with different solid-liquid slurry separation techniques were done. The result showed that the anaerobic digestion (AD) process was inhibited when raw and liquid fractions of sow, pig and dairy cow acidified slurry are digested, but AD treating solid fractions (SF) acidified slurry showed no sulphide inhibition. The B(0) of SF acidified sow slurry increased significantly with increasing screen size in the screw press. No significant effect of acidification processes on B(0) of SF dairy cow slurry (DCS) was observed. The ultimate methane yields of SF acidified DCS and SF non acidified DCS were 278±13 and 289±1LkgVS(-1), while in term of fresh weigh substrate were 59±2.8 and 59±0.3Lkgsubstrate(-1), respectively. PMID:23313767

  1. Long-term forest management effects on streamflow and evapotranspiration: modeling the interaction of vegetation and climate at the catchment scale

    NASA Astrophysics Data System (ADS)

    Ford, C. R.; Vose, J.

    2011-12-01

    Forested watersheds, an important provider of ecosystems services related to water supply, can have their structure, function, and resulting streamflow substantially altered by land use and land cover. Using a retrospective analysis and synthesis of long-term climate and streamflow data (75 years) from six watersheds differing in management histories we explored whether streamflow, and thus evapotranspiration, responded differently to variation in annual temperature and extreme precipitation than unmanaged watersheds. We used a hybrid modeling approach that incorporated terms for the classic paired watershed regression, the response of the vegetation regrowth, and the interaction of vegetation regrowth and precipitation. We show significant increases in temperature and the frequency of extreme wet and dry years since the 1980s. Response models explained almost all streamflow variability (R2adj > 0.99). In all cases, changing land use altered streamflow. Observed watershed responses differed significantly in wet and dry extreme years in all but a stand managed as a coppice forest. Converting deciduous stands to pine altered the streamflow response to extreme annual precipitation the most; the apparent frequency of observed extreme wet years decreased on average by 7-fold. This effect was attributable partially to increased interception, but also to increased transpiration in the pine stand compared to the unmanaged, deciduous hardwood stand as indicated by sap flow studies on individual species. This increased soil water storage may reduce flood risk in wet years, but create conditions that could exacerbate drought. Forest management can potentially mitigate extreme annual precipitation associated with climate change; however, offsetting effects suggest the need for spatially-explicit analyses of risk and vulnerability, as well as an increased understanding of the relative contributions of interception and transpiration across species and community types. To address

  2. Vegetation impact on mean annual evapotranspiration at a global catchment scale

    NASA Astrophysics Data System (ADS)

    Peel, Murray C.; McMahon, Thomas A.; Finlayson, Brian L.

    2010-09-01

    Research into the role of catchment vegetation within the hydrologic cycle has a long history in the hydrologic literature. Relationships between vegetation type and catchment evapotranspiration and runoff were primarily assessed through paired catchment studies during the 20th century. Results from over 200 paired catchment studies from around the world have been reported in the literature. Two constraints on utilizing the results from paired catchment studies in the wider domain have been that the catchment areas studied are generally (1) small (<10 km2) and (2) from a narrow range of climate types. The majority of reported paired catchment studies are located in the USA (˜47%) and Australia (˜27%) and experience mainly temperate (Köppen C) and cold (Köppen D) climate types. In this paper we assess the impact of vegetation type on mean annual evapotranspiration through a large, spatially, and climatically diverse data set of 699 catchments from around the world. These catchments are a subset of 861 unregulated catchments considered for the analysis. Spatially averaged precipitation and temperature data, in conjunction with runoff and land cover information, are analyzed to draw broad conclusions about the vegetation impact on mean annual evapotranspiration. In this analysis any vegetation impact signal is assessed through differences in long-term catchment average actual evapotranspiration, defined as precipitation minus runoff, between catchments grouped by vegetation type. This methodology differs from paired catchment studies where vegetation impact is assessed through streamflow responses to a controlled, within catchment, land cover change. The importance of taking the climate type experienced by the catchments into account when assessing the vegetation impact on evapotranspiration is demonstrated. Tropical and temperate forested catchments are found to have statistically significant higher median evapotranspiration, by about 170 mm and 130 mm

  3. Effects of acidifying reagents on microwave treatment of dairy manure.

    PubMed

    Srinivasan, Asha; Nkansah-Boadu, Frank; Liao, Ping H; Lo, Kwang V

    2014-01-01

    Dairy manure, acidified using organic acids (acetic, oxalic, and citric acid) were treated with microwave enhanced advanced oxidation process (MW/H2O2-AOP). The effect of a mixture of oxalic acid and commonly used mineral acids (sulfuric and hydrochloric acid) on MW/H2O2-AOP was also examined. Substantial amounts of phosphorus were released under MW/H2O2-AOP, regardless of organic acid or mineral acid used. All three organic acids were good acidifying reagents; however, only oxalic acid could remove free calcium ion in the solution, and improve settleability of dairy manure. The MW/H2O2-AOP and calcium removal process could be combined into a single-stage process, which could release phosphate, solubilize solids and remove calcium from dairy manure at the same time. A mixture of oxalic acid and mineral acid produced the maximum volume of clear supernatant and had an ideal molar ratio of calcium to magnesium for effective struvite (magnesium ammonium phosphate) crystallization process. A single-stage MW/H2O2-AOP would simplify the process and reduce mineral acid consumption compared to a two-stage operation. The results of a pilot scale study demonstrate that MW/H2O2-AOP is effective in treating manure and recovering resource from dairy farms. PMID:24813989

  4. Modelling hydrological management for the restoration of acidified floating fens

    NASA Astrophysics Data System (ADS)

    Dekker, Stefan C.; Barendregt, Aat; Bootsma, Margien C.; Schot, Paul P.

    2005-12-01

    Wetlands show a large decline in biodiversity. To protect and restore this biodiversity, many restoration projects are carried out. Hydrology in wetlands controls the chemical and biological processes and may be the most important factor regulating wetland function and development. Hydrological models may be used to simulate these processes and to evaluate management scenarios for restoration. HYDRUS2D, a combined saturated-unsaturated groundwater flow and transport model, is presented. This simulates near-surface hydrological processes in an acidified floating fen, with the aim to evaluate the effect of hydrological restoration in terms of conditions for biodiversity. In the acidified floating fen in the nature reserve Ilperveld (The Netherlands), a trench system was dug for the purpose of creating a runoff channel for acid rainwater in wet periods and to enable circum-neutral surface water to enter the fen in dry periods. The model is calibrated against measured conductivity values for a 5 year period. From the model simulations, it was found that lateral flow in the floating raft is limited. Furthermore, the model shows that the best management option is a combination of trenches and inundation, which gave the best soil water quality in the root zone. It is concluded that hydrological models can be used for the calculation of management scenarios in restoration projects. The combined saturated-unsaturated model concept used in this paper is able to incorporate the governing hydrological processes in the wetland root zones. Copyright

  5. History of forest hydrology

    NASA Astrophysics Data System (ADS)

    McCulloch, James S. G.; Robinson, Mark

    1993-10-01

    Hydrology as a science and a technology is examined, as are some of the myths on the role of forests in hydrology and water resources. The history of catchment area research is traced, in Europe, in the USA and in East Africa, with particular reference to forest hydrology and, in the earlier years, to water quantity rather than water quality. The importance of associating physical process studies with hydrological systems' investigations, to enhance understanding of why particular catchments behave as they do, is stressed. Recent advances in hydrochemistry have been exploited to elucidate water flow paths within experimental catchments. Stimulated by requirements for research into acidification of surface waters, research catchments have proved to be valuable outdoor laboratories from which a much improved understanding of the flow processes has been achieved. Conflicting claims about the impacts of forestry are described and discussed.

  6. Physiological ecology of Mougeotia (Zygnemataceae) from an experimentally acidified lake

    SciTech Connect

    Arancibia-Avila, P.E.

    1994-01-01

    Filamentous green algae were collected in July, 1989, from metaphytic blooms that occurred in the acidified (pH 5.2) basin, but not an unacidified reference basin (pH 6.1) of Little Rock Lake, Vilas Co., WI. Isolates of a Mougeotia species and Spirogyra reflexa were cultured at pH 5.5, with aeration. Measurements Of O[sub 2] production in a factorial experiment revealed optimal irradiance and temperature for photosynthesis in Mougeotia were 2500 [mu]E[center dot]m[sup [minus]2][center dot]s[sup [minus]l] and 25[degrees]C. Additional O[sub 2] evolution measurements showed that the optimal pH for Mougeotia photosynthesis was 8, but that net photosynthesis was positive from pH 8 to 3. Further studies indicated that Mougeotia was tolerant to concentrations of zinc and aluminum that were greater than levels observed in the acidified basin of the lake. Since inorganic carbon (C[sub i]) is known to limit Mougeotia photosynthesis and growth in acidified lakes, the occurrence of carbonic anhydrase (CA) as a mechanism for uptake and concentration of C[sub i] was investigated. No CA activity was detected in S. reflexa. In contrast, both external and internal CA were measured in Mougeotia at pH 3.7 and at pH 8. By comparison to pH 8, at pH 3.7 external CA activity increased by a factor of about 2. An antibody to Chlamydomonas external CA was used to localize CA in the plasma membrane and cell wall of both Chlamydomonas and Mougeotia. When unaerated (DIC-limited) Mougeotia was grown in SD11 medium supplemented with 1% glucose, chlorophyll a levels were significantly higher than for cultures grown without sugar. Chloroplast morphology was also judged superior for sugar-supplemented cultures. The data suggest that Mougeotia possesses a DIC-concentrating system, and may also be able to import DOC (glucose).

  7. Soil wettability in forested catchments in South Africa; as measured by different methods and as affected by vegetation cover and soil characteristics

    NASA Astrophysics Data System (ADS)

    Scott, D. F.

    2000-05-01

    Earlier studies in South Africa had shown that water repellency in the soils of timber plantations was associated with a greater risk of overland flow and soil erosion on mountain slopes. This paper reports on a follow-up study to determine how prevalent water repellent soils are in the forestry areas of South Africa, and to what extent this phenomenon is associated with specific vegetation types. Soils from a representative series of forestry sites around South Africa were sampled from beneath each genus or plantation type and the range of local vegetation types. These soils were dried at low oven temperatures and then subjected to a series of tests of soil wettability, namely, water drop penetration time, infiltration rate, critical surface tension and apparent advancing contact angle as determined by the equilibrium capillary rise test. Water repellency is common in dried soils from timber plantations. The dominant variation in repellency is explained by the different vegetation types: soils beneath eucalypts are most repellent, followed by those beneath wattle ( Acacia species), indigenous forest and pine. Soils beneath grassland and fynbos scrub were least likely to show repellency, perhaps because regular fires remove plant litter and thus the potential for hydrophobic substances to develop. Soil characteristics explained very little of the variation in repellency. Organic carbon content was weakly correlated with higher repellency, but organic carbon content and soil texture added little explanation to models that first accounted for variation in vegetation type and point of origin. These results are broadly the same regardless of which method of measuring repellency was used. However, the critical surface tension test was far superior to the others in terms of information gained, speed, efficiency and statistical utility of the resultant scores.

  8. Can the eastern red-backed salamander (Plethodon cinereus) persist in an acidified landscape?

    USGS Publications Warehouse

    Bondi, Cheryl A; Beier, Colin M.; Ducey, Peter K; Lawrence, Gregory B.; Bailey, Scott W.

    2016-01-01

    Hardwood forests of eastern North America have experienced decades of acidic deposition, leading to soil acidification where base cation supply was insufficient to neutralize acid inputs. Negative impacts of soil acidity on amphibians include disrupted embryonic development, lower growth rates, and habitat loss. However, some amphibians exhibit intraspecific variation in acid tolerance, suggesting the potential for local adaptation in areas where soils are naturally acidic. The eastern red-backed salamander (Plethodon cinereus) is a highly abundant top predator of the northern hardwood forest floor. Early research found that P. cinereus was sensitive to acidic soils, avoiding substrates with pH < 3.8 and experiencing decreased growth rates in acidic habitats. However, recent studies have documented P. cinereus populations in lower pH conditions than previously observed, suggesting some populations may persist in acidic conditions. Here, we evaluated relationships between organic horizon soil pH and P. cinereus abundance, adult health (body size and condition), and microhabitat selection, based on surveys of 34 hardwood forests in northeastern United States that encompass a regional soil pH gradient. We found no associations between soil pH and P. cinereus abundance or health, and observed that this salamander used substrates with pH similar to that available, suggesting that pH does not mediate their fine-scale distributions. The strongest negative predictor of P. cinereus abundance was the presence of dusky salamanders (Desmognathus spp.), which were most abundant in the western Adirondacks. Our results indicate that P. cinereus occupies a wider range of soil pH than has been previously thought, which has implications for their functional role in forest food webs and nutrient cycles in acid-impaired ecosystems. Tolerance of P. cinereus for more acidic habitats, including anthropogenically acidified forests, may be due to local adaptation in

  9. Improvement of heating uniformity in packaged acidified vegetables pasteurized with a 915 MHz continuous microwave system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Continuous microwave processing to produce shelf-stable acidified vegetables with moderate to high salt contents poses challenges in pasteurization due to reduced microwave penetration depths and non-uniform heating. Cups of sweetpotato, red bell pepper, and broccoli acidified to pH 3.8 with citric...

  10. Growth potential of Clostridium perfringens from spores in acidified beef, pork and poultry products during chilling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of C. perfringens to germinate and grow in acidified ground beef as well as in ten commercially prepared acidified beef, pork and poultry products was assessed. The pH of ground beef was adjusted using organic vinegar to achieve various pH values between 5.0 and 5.6; the pH of the commer...

  11. Nitrogen isotopes as indicators of streamflow generation processes in a headwater forested catchment: Focusing on atmospheric NO3- contribution using δ 18O signature

    NASA Astrophysics Data System (ADS)

    Ohte, N.; Sebestyen, S. D.; Doctor, D. H.; Wankel, S. D.; Shanley, J. B.; Kendall, C.; Boyer, E. W.

    2003-12-01

    were enabled by the dual-isotope analysis of NO3-. The fine resolution isotope analysis of NO3- in our experiment can provide advantages for elucidating the discharge mechanisms of nitrogen in forested watersheds with high atmospheric nitrogen depositions.

  12. Geochemical and isotopic evolution of soil solutions over the last 25 years in a forested granitic catchment (the experimental Strengbach watershed case, France).

    NASA Astrophysics Data System (ADS)

    Pierret, M.-C.; Prunier, J.; Stille, P.; Chabaux, F.

    2009-04-01

    that the annual dry and wet atmospheric inputs in Ca, Na, K, Mg, Si remain constant since 1986. Then the decrease of the Ca concentration with time, in the two profiles, cannot be related to diminution of dissolution processes nor to declining of atmospheric inputs. At the same time, the evolution of the Sr isotopic ratios in soil solutions in depth below 30 cm, which become more radiogenic, shows that the source of elements also changed. Apatite, which is the main source of Ca in this system almost has disappeared from the upper most levels of soils. The contribution to the flux of Ca from secondary minerals such as clays or of exchangeable fraction increases. At the present time, these phases represent a new main source of Ca, more radiogenic in Sr. All our results lead us to propose that the source of Ca in soils decreased for the past 20 years which raises the problems of the present-day nutrient availability in forested soils, such as those developed in acid granitic bedrock.

  13. Comparison of a Powdered, Acidified Liquid, and Non-Acidified Liquid Human Milk Fortifier on Clinical Outcomes in Premature Infants

    PubMed Central

    Thoene, Melissa; Lyden, Elizabeth; Weishaar, Kara; Elliott, Elizabeth; Wu, Ruomei; White, Katelyn; Timm, Hayley; Anderson-Berry, Ann

    2016-01-01

    We previously compared infant outcomes between a powdered human milk fortifier (P-HMF) vs. acidified liquid HMF (AL-HMF). A non-acidified liquid HMF (NAL-HMF) is now commercially available. The purpose of this study is to compare growth and outcomes of premature infants receiving P-HMF, AL-HMF or NAL-HMF. An Institutional Review Board (IRB) approved retrospective chart review compared infant outcomes (born < 2000 g) who received one of three HMF. Growth, enteral nutrition, laboratory and demographic data were compared. 120 infants were included (P-HMF = 46, AL-HMF = 23, NAL-HMF = 51). AL-HMF infants grew slower in g/day (median 23.66 vs. P-HMF 31.27, NAL-HMF 31.74 (p < 0.05)) and in g/kg/day, median 10.59 vs. 15.37, 14.03 (p < 0.0001). AL-HMF vs. NAL-HMF infants were smaller at 36 weeks gestational age (median 2046 vs. 2404 g, p < 0.05). However AL-HMF infants received more daily calories (p = 0.21) and protein (p < 0.0001), mean 129 cal/kg, 4.2 g protein/kg vs. P-HMF 117 cal/kg, 3.7 g protein/kg , NAL-HMF 120 cal/kg, 4.0 g protein/kg. AL-HMF infants exhibited lower carbon dioxide levels after day of life 14 and 30 (p < 0.0001, p = 0.0038). Three AL-HMF infants (13%) developed necrotizing enterocolitis (NEC) vs. no infants in the remaining groups (p = 0.0056). A NAL-HMF is the most optimal choice for premature human milk-fed infants in a high acuity neonatal intensive care unit (NICU). PMID:27472359

  14. Comparison of a Powdered, Acidified Liquid, and Non-Acidified Liquid Human Milk Fortifier on Clinical Outcomes in Premature Infants.

    PubMed

    Thoene, Melissa; Lyden, Elizabeth; Weishaar, Kara; Elliott, Elizabeth; Wu, Ruomei; White, Katelyn; Timm, Hayley; Anderson-Berry, Ann

    2016-01-01

    We previously compared infant outcomes between a powdered human milk fortifier (P-HMF) vs. acidified liquid HMF (AL-HMF). A non-acidified liquid HMF (NAL-HMF) is now commercially available. The purpose of this study is to compare growth and outcomes of premature infants receiving P-HMF, AL-HMF or NAL-HMF. An Institutional Review Board (IRB) approved retrospective chart review compared infant outcomes (born < 2000 g) who received one of three HMF. Growth, enteral nutrition, laboratory and demographic data were compared. 120 infants were included (P-HMF = 46, AL-HMF = 23, NAL-HMF = 51). AL-HMF infants grew slower in g/day (median 23.66 vs. P-HMF 31.27, NAL-HMF 31.74 (p < 0.05)) and in g/kg/day, median 10.59 vs. 15.37, 14.03 (p < 0.0001). AL-HMF vs. NAL-HMF infants were smaller at 36 weeks gestational age (median 2046 vs. 2404 g, p < 0.05). However AL-HMF infants received more daily calories (p = 0.21) and protein (p < 0.0001), mean 129 cal/kg, 4.2 g protein/kg vs. P-HMF 117 cal/kg, 3.7 g protein/kg , NAL-HMF 120 cal/kg, 4.0 g protein/kg. AL-HMF infants exhibited lower carbon dioxide levels after day of life 14 and 30 (p < 0.0001, p = 0.0038). Three AL-HMF infants (13%) developed necrotizing enterocolitis (NEC) vs. no infants in the remaining groups (p = 0.0056). A NAL-HMF is the most optimal choice for premature human milk-fed infants in a high acuity neonatal intensive care unit (NICU). PMID:27472359

  15. Reduction of hexavalent chromium in water samples acidified for preservation

    USGS Publications Warehouse

    Stollenwerk, K.G.; Grove, D.B.

    1985-01-01

    Reduction of hexavalent chromium, Cr(VI), in water samples, preserved by standard techniques, was investigated. The standard preservation technique for water samples that are to be analyzed for Cr(VI) consists of filtration through a 0.45-??m membrane, acidification to a pH < 2, and storage in plastic bottles. Batch experiments were conducted to evaluate the effect of H+ concentration, NO2, temperature, and dissolved organic carbon (DOC) on the reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) to Cr(III) increased with increasing NO2, DOC, H+, and temperature. Reduction of Cr(VI) by organic matter occurred in some samples even though the samples were unacidified. Reduction of Cr(VI) is inhibited to an extent by storing the sample at 4??C. Stability of Cr(VI) in water is variable and depends on the other constituents present in the sample. Water samples collected for the determination of Cr(VI) should be filtered (0.45-??m membrane), refrigerated, and analyzed as quickly as possible. Water samples should not be acidified. Measurement of total Cr in addition to Cr(VI) can serve as a check for Cr(VI) reduction. If total Cr is greater than Cr(VI), the possibility that Cr(VI) reduction has occurred needs to be considered.The rate of reduction of Cr(VI) to Cr(III) increased with increasing NO//2, DOC, H** plus , and temperature. Reduction of Cr(VI) by organic matter occurred in some samples even though the samples were unacidified. Reduction of Cr(VI) is inhibited to an extent by storing the sample at 4 degree C. Stability of Cr(VI) in water is variable and depends on the other constituents present in the sample. Water samples collected for the determination of Cr(VI) should be filtered (0. 45- mu m membrane), refrigerated, and analyzed as quickly as possible. Water samples should not be acidified. Measurement of total Cr in addition to Cr(VI) can serve as a check for Cr(VI) reduction. If total Cr is greater than Cr(VI), the possibility that Cr

  16. Enhancing toxic metal removal from acidified sludge with nitrite addition.

    PubMed

    Du, Fangzhou; Freguia, Stefano; Yuan, Zhiguo; Keller, Jürg; Pikaar, Ilje

    2015-05-19

    The production of sludge (biosolids) during wastewater treatment is a major issue for water utilities. A main issue limiting its beneficial reuse on agricultural lands is the presence of toxic metals. The currently used metal reduction technologies achieve insufficient removal of metals that are bound to the organic fraction of the sludge. In this study, we propose and demonstrate a novel method that involves the addition of nitrite during sludge acidification to enhance metal removal. Using waste activated sludge collected from three full-scale wastewater treatment plants, we found that acidification to pH 2.0 achieved good Zn solubilization of around 70%, but only 3-7% of Cu was being dissolved. Nitrite addition to the acidified sludge at a concentration of 20 mg NO2(-)-N/L (equals to 19.2 mg HNO2-N/L), substantially enhanced Cu removal to 45-64%, while Zn removal was also increased to over 81%. Metal distribution analysis using sequential chemical extraction revealed that the improvement of Cu and Zn removal was mainly due to the release of the organically bound metal fraction. We hypothesize that free nitrous acid (HNO2, FNA) may assist in the (partial) disruption of extracellular polymeric substances (EPS) and the subsequent release and solubilization of fixed metals. PMID:25872418

  17. A Reacidification Model for Acidified Lakes Neutralized With Calcite

    NASA Astrophysics Data System (ADS)

    Sverdrup, Harald; Warfvinge, Per

    1985-09-01

    In lake liming operations in Sweden, acidified lakes are reclaimed by neutralization with calcite powder. The amount added is intended to neutralize the water column as well as to delay the reacidification. The reacidification of limed lakes is dependent on the dilution of the dissolved calcium carbonate with time and, for a limited period of time, the dissolution of calcite from the lake sediments. Calcite on the lake bottom will, in addition to being covered by sedimentation, become inactivated by precipitates of humus and clay minerals clogging the calcite surfaces. A model has been developed to calculate the reacidification of a limed lake which includes the following mechanisms: (1) the dissolution of calcite and a subsequent neutralization of acid water, (2) owing to the increase inpH value, occurrence of precipitation of humus and dissolved metals onto the calcite surface and inhibition of the dissolution of calcite (3) reversible sorbtion of calcium from the water column by sediments not covered with calcite, and (4) diffusive transport through a boundary bottom layer to the water column. In a first approach the lake was modeled as a continuously stirred tank. The equations were derived from a mass balance and the dissolution kinetics for calcite to describe the long-term development ofpH, alkalinity, and calcium concentration in the lake. The differential equations describing the mechanisms were solved with the help of a computer code. The model accurately describes the reacidification and the mass balances observed in several limed lakes.

  18. Factors controlling inter-catchment variation of mean transit time with consideration of temporal variability

    NASA Astrophysics Data System (ADS)

    Ma, Wenchao; Yamanaka, Tsutomu

    2016-03-01

    The catchment transit time, a lumped descriptor reflecting both time scale and spatial structure of catchment hydrology can provide useful insights into chemical/nuclear pollution risks within a catchment. Despite its importance, factors controlling spatial variation of mean transit time (MTT) are not yet well understood. In this study, we estimated time-variant MTTs for about ten years (2003-2012) in five mesoscale sub-catchments of the Fuji River catchment, central Japan, to establish the factors controlling their inter-catchment variation with consideration of temporal variability. For this purpose, we employed a lumped hydrological model that was calibrated and validated by hydrometric and isotopic tracer observations. Temporal variation patterns of estimated MTT were similar in all sub-catchments, but with differing amplitudes. Inter-catchment variation of MTT was greater in dry periods than wet periods, suggesting spatial variation of MTT is controlled by water 'stock' rather than by 'flow'. Although the long-term average MTT (LAMTT) in each catchment was correlated with mean slope, coverage of forest (or conversely, other land use types), coverage of sand-shale conglomerate, and groundwater storage, the multiple linear regression revealed that inter-catchment variation of LAMTT is principally controlled by the amount of groundwater storage. This is smaller in mountainous areas covered mostly by forests and greater in plain areas with less forest coverage and smaller slope. This study highlights the topographic control of MTT via groundwater storage, which might be a more important factor in mesoscale catchments, including both mountains and plains, rather than in smaller catchments dominated by mountainous topography.

  19. The Hydrologic Response of a Small Catchment to Clear Cutting

    NASA Astrophysics Data System (ADS)

    Abdelnour, A.; Stieglitz, M.; Pan, F.; McKane, R. B.

    2006-12-01

    We simulated how a landscape disturbance (i.e., fire or clear-cutting) alters hillslope and catchment hydrologic processes. Specifically, we simulated how the pattern and magnitude of tree removal in a catchment increases downslope transport of water and alters catchment soil moisture and discharge. The study site is the WS10 catchment of the HJ Andrews LTER, located in the Pacific NorthWest, USA. We used a spatially- explicit hydrologic model comprised of connected landscape units. We implicitly model biomass removal and the subsequent forest re-growth by manipulating evapotranspiration. We allow potential evapotranspiration to increase exponentially from zero at the onset of the disturbance to pre-disturbance values within a 40 years period. Simulations show that while soil moisture in the uplands increased in post-disturbance period, downslope flow increased only minimally. In this catchment, upland soil moisture stayed well below field capacity, and therefore, downslope lateral flow was not initiated. As such, midland and lowland soil moisture, as well as catchment discharge, remained near pre-disturbance values throughout the re-growth period. This behavior in catchment dynamics resulted primarily from the fact that seasonal temperatures and precipitations are out of phase in this region of the US.

  20. The fate of sulfate in acidified pig slurry during storage and following application to cropped soil.

    PubMed

    Eriksen, Jørgen; Sørensen, Peter; Elsgaard, Lars

    2008-01-01

    Acidification of slurry with sulfuric acid is a recent agricultural practice that may serve a double purpose: reducing ammonia emission and ensuring crop sulfur sufficiency. We investigated S transformations in untreated and acidified pig slurry stored for up to 11 mo at 2, 10, or 20 degrees C. Furthermore, the fertilizer efficiency of sulfuric acid in acidified slurry was investigated in a pot experiment with spring barley. The sulfate content from acidification with sulfuric acid was relatively stable and even after 11 mo of storage the majority was in the plant-available sulfate form. Microbial sulfate reduction during storage of acidified pig slurry was limited, presumably due to initial pH effects and a limitation in the availability of easily degradable organic matter. Sulfide accumulation was observed during storage but the sulfide levels in acidified slurry did not exceed those of the untreated slurry for several months after addition. The S fertilizer value of the acidified slurry was considerable as a result of the stable sulfate pool during storage. The high content of inorganic S in the acidified slurry may potentially lead to development of odorous volatile sulfur-containing compounds and investigations are needed into the relationship between odor development and the C and S composition of the slurry. PMID:18178902

  1. Release of Nitrogen and Phosphorus from Poultry Litter Amended with Acidified Biochar

    PubMed Central

    Doydora, Sarah A.; Cabrera, Miguel L.; Das, Keshav C.; Gaskin, Julia W.; Sonon, Leticia S.; Miller, William P.

    2011-01-01

    Application of poultry litter (PL) to soil may lead to nitrogen (N) losses through ammonia (NH3) volatilization and to potential contamination of surface runoff with PL-derived phosphorus (P). Amending litter with acidified biochar may minimize these problems by decreasing litter pH and by retaining litter-derived P, respectively. This study evaluated the effect of acidified biochars from pine chips (PC) and peanut hulls (PH) on NH3 losses and inorganic N and P released from surface-applied or incorporated PL. Poultry litter with or without acidified biochars was surface-applied or incorporated into the soil and incubated for 21 d. Volatilized NH3 was determined by trapping it in acid. Inorganic N and P were determined by leaching the soil with 0.01 M of CaCl2 during the study and by extracting it with 1 M KCl after incubation. Acidified biochars reduced NH3 losses by 58 to 63% with surface-applied PL, and by 56 to 60% with incorporated PL. Except for PH biochar, which caused a small increase in leached NH4 +-N with incorporated PL, acidified biochars had no effect on leached or KCl-extractable inorganic N and P from surface-applied or incorporated PL. These results suggest that acidified biochars may decrease NH3 losses from PL but may not reduce the potential for P loss in surface runoff from soils receiving PL. PMID:21655132

  2. Elevated Colonization of Microborers at a Volcanically Acidified Coral Reef

    PubMed Central

    Enochs, Ian C.; Manzello, Derek P.; Tribollet, Aline; Valentino, Lauren; Kolodziej, Graham; Donham, Emily M.; Fitchett, Mark D.; Carlton, Renee; Price, Nichole N.

    2016-01-01

    Experiments have demonstrated that ocean acidification (OA) conditions projected to occur by the end of the century will slow the calcification of numerous coral species and accelerate the biological erosion of reef habitats (bioerosion). Microborers, which bore holes less than 100 μm diameter, are one of the most pervasive agents of bioerosion and are present throughout all calcium carbonate substrates within the reef environment. The response of diverse reef functional groups to OA is known from real-world ecosystems, but to date our understanding of the relationship between ocean pH and carbonate dissolution by microborers is limited to controlled laboratory experiments. Here we examine the settlement of microborers to pure mineral calcium carbonate substrates (calcite) along a natural pH gradient at a volcanically acidified reef at Maug, Commonwealth of the Northern Mariana Islands (CNMI). Colonization of pioneer microborers was higher in the lower pH waters near the vent field. Depth of microborer penetration was highly variable both among and within sites (4.2–195.5 μm) over the short duration of the study (3 mo.) and no clear relationship to increasing CO2 was observed. Calculated rates of biogenic dissolution, however, were highest at the two sites closer to the vent and were not significantly different from each other. These data represent the first evidence of OA-enhancement of microboring flora colonization in newly available substrates and provide further evidence that microborers, especially bioeroding chlorophytes, respond positively to low pH. The accelerated breakdown and dissolution of reef framework structures with OA will likely lead to declines in structural complexity and integrity, as well as possible loss of essential habitat. PMID:27467570

  3. Elevated Colonization of Microborers at a Volcanically Acidified Coral Reef.

    PubMed

    Enochs, Ian C; Manzello, Derek P; Tribollet, Aline; Valentino, Lauren; Kolodziej, Graham; Donham, Emily M; Fitchett, Mark D; Carlton, Renee; Price, Nichole N

    2016-01-01

    Experiments have demonstrated that ocean acidification (OA) conditions projected to occur by the end of the century will slow the calcification of numerous coral species and accelerate the biological erosion of reef habitats (bioerosion). Microborers, which bore holes less than 100 μm diameter, are one of the most pervasive agents of bioerosion and are present throughout all calcium carbonate substrates within the reef environment. The response of diverse reef functional groups to OA is known from real-world ecosystems, but to date our understanding of the relationship between ocean pH and carbonate dissolution by microborers is limited to controlled laboratory experiments. Here we examine the settlement of microborers to pure mineral calcium carbonate substrates (calcite) along a natural pH gradient at a volcanically acidified reef at Maug, Commonwealth of the Northern Mariana Islands (CNMI). Colonization of pioneer microborers was higher in the lower pH waters near the vent field. Depth of microborer penetration was highly variable both among and within sites (4.2-195.5 μm) over the short duration of the study (3 mo.) and no clear relationship to increasing CO2 was observed. Calculated rates of biogenic dissolution, however, were highest at the two sites closer to the vent and were not significantly different from each other. These data represent the first evidence of OA-enhancement of microboring flora colonization in newly available substrates and provide further evidence that microborers, especially bioeroding chlorophytes, respond positively to low pH. The accelerated breakdown and dissolution of reef framework structures with OA will likely lead to declines in structural complexity and integrity, as well as possible loss of essential habitat. PMID:27467570

  4. Hydrograph separation in headwater catchments of the Andes using water isotope composition

    NASA Astrophysics Data System (ADS)

    Roa Garcia, C.; Weiler, M.

    2009-04-01

    Water isotopes have been used in hydrology for two purposes: 1) identify the age of water when it leaves a catchment, both for baseflow and for individual storms; and 2) identify the source of water that leaves the catchment during and after a precipitation event, (e.g. whether it comes from rain or from particular water reservoirs within the catchment). This knowledge has been used to understand the interactions between precipitation and catchments and as a proxy for the capacity of a catchment to store water and regulate its flow, which is particularly relevant for water managers. This study has taken three small neighboring catchments and one sub-catchment in each of them containing a wetland, to analyze their baseflow and discharge response to rain events using TRANSEP. The objectives of this study are: 1) to compare the hydrological response of the six units to test the hypothesis that connected units of the landscape e.g. wetlands have a large influence on catchment yield; 2) to analyze the effect of land use on water yield during rain events; and 3) to analyze the effects of land use on baseflow. Results indicate that for B1, the catchment with 68% of area in forest, discharge is predominantly quickflow (70%), whereas for the other two catchments, it comes from around 50% of both the quickflow reservoir and the persistent reservoir. The big influence from wetlands is seen in two results: 1) the higher proportion of baseflow discharge for BB, the catchment with a 6% of total area in wetlands, since wetlands could be contributing to groundwater recharge; 2) the mean transit time of water in BB, 172 days compared with 97 days for B1 (the forested catchment) and 28 days for B2 (the catchment with 69% in grasslands) influenced by the longer transit time for BBW and B2W. The larger proportion of discharge coming from the slow quickflow in wetlands B2 and BB, and their mean transit times, indicate that the water stored in wetlands, despite constituting surface

  5. Influence of vegetation on water isotope partitioning across different northern headwater catchments

    NASA Astrophysics Data System (ADS)

    Gabor, R. S.; Tetzlaff, D.; Buttle, J. M.; Carey, S. K.; Laudon, H.; Mitchell, C. P. J.; McNamara, J. P.; Soulsby, C.

    2014-12-01

    The hydrology of high latitude catchments is sensitive to small changes in temperature, and likely to be impacted by changes in climate. Vegetation water usage can play a large role in catchment hydrologic pathways, affecting how water is stored, released, and partitioned within a landscape. Thus a better understanding of how vegetation impacts water partitioning in northern catchments can help us understand how climate change will impact high-latitude hydrology. As part of the VeWa project, five catchments were chosen between 44oN and 64oN in Europe and North America, to compare the role of vegetation in the movement of water across northern landscapes. These catchments vary in aspect as well as extent of snowpack and their vegetative landscapes include heather moorland, coniferous and deciduous forests, mixed grass, and tundra landscapes. Importantly, all the catchments have records of stable isotopes in different waters of the system. An initial comparison of the water isotopes in these catchments demonstrates variation between the catchments, with the lower latitude sites showing more fractionation suggestive of evapotranspiration. While all catchments show a depletion of heavy isotopes in the spring, the depletion is most evident in catchments with a heavier snowpack. The vegetative growing season during the summer months shows the greatest impact of evapotranspiration on isotopes, indicating that an increased summer in a warmer climate would likely alter water partitioning and storage dynamics in these regions.

  6. Modeling relationships between catchment attributes and river water quality in southern catchments of the Caspian Sea.

    PubMed

    Hasani Sangani, Mohammad; Jabbarian Amiri, Bahman; Alizadeh Shabani, Afshin; Sakieh, Yousef; Ashrafi, Sohrab

    2015-04-01

    Increasing land utilization through diverse forms of human activities, such as agriculture, forestry, urban growth, and industrial development, has led to negative impacts on the water quality of rivers. To find out how catchment attributes, such as land use, hydrologic soil groups, and lithology, can affect water quality variables (Ca(2+), Mg(2+), Na(+), Cl(-), HCO 3 (-) , pH, TDS, EC, SAR), a spatio-statistical approach was applied to 23 catchments in southern basins of the Caspian Sea. All input data layers (digital maps of land use, soil, and lithology) were prepared using geographic information system (GIS) and spatial analysis. Relationships between water quality variables and catchment attributes were then examined by Spearman rank correlation tests and multiple linear regression. Stepwise approach-based multiple linear regressions were developed to examine the relationship between catchment attributes and water quality variables. The areas (%) of marl, tuff, or diorite, as well as those of good-quality rangeland and bare land had negative effects on all water quality variables, while those of basalt, forest land cover were found to contribute to improved river water quality. Moreover, lithological variables showed the greatest most potential for predicting the mean concentration values of water quality variables, and noting that measure of EC and TDS have inversely associated with area (%) of urban land use. PMID:25395322

  7. Changes in catchment hydrology in relation to vegetation recovery: a comparative modelling experiment

    NASA Astrophysics Data System (ADS)

    Lana-Renault, Noemí; Karssenberg, Derek; Latron, Jérôme; Serrano, Mā Pilar; Regüés, David; Bierkens, Marc F. P.

    2010-05-01

    Mediterranean mountains have been largely affected by land abandonment and subsequent vegetation recovery, with a general expansion of shrubs and forests. Such a large scale land-cover change has modified the hydrological behavior of these areas, with significant impact on runoff production. Forecasting the trend of water resources under future re-vegetation scenarios is of paramount importance in Mediterranean basins, where water management relies on runoff generated in these areas. With this purpose, a modelling experiment was designed based on the information collected in two neighbouring research catchments with a different history of land use in the central Spanish Pyrenees. One (2.84 km2) is an abandoned agricultural catchment subjected to plant colonization and at present mainly covered by shrubs. The other (0.92 km2) is a catchment covered by dense natural forest, representative of undisturbed environments. Here we present the results of the analysis of the hydrological differences between the two catchments, and a description of the approach and results of the modelling experiment. In a statistical analysis of the field data, significant differences were observed in the streamflow response of the two catchments. The forested catchment recorded fewer floods per year compared to the old agricultural catchment, and its hydrological response was characterised by a marked seasonality, with autumn and spring as the only high flow periods. Stormflow was generally higher in the old agricultural catchment, especially for low to intermediate size events; only for large events the stormflow in the forested catchment was sometimes greater. Under drier conditions, the relative differences in the stormflow between the two catchments tended to increase whereas under wet conditions they tended to be similar. The forested catchment always reacted more slowly to rainfall, with lower peakflows (generally one order of magnitude lower) and longer recession limbs. The modelling

  8. Leaf breakdown in streams differing in catchment land use

    USGS Publications Warehouse

    Paul, M.J.; Meyer, J.L.; Couch, C.A.

    2006-01-01

    1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runoff was significantly higher in urban and suburban catchments that had higher impervious surface cover than forested or agricultural catchments. 4. We propose that processes accelerating leaf breakdown in agricultural and urban streams were not the same: faster breakdown in agricultural streams was due to increased biological activity as a result of nutrient enrichment, whereas faster breakdown in urban streams was a result of physical fragmentation resulting from higher storm runoff. ?? 2006 The Authors.

  9. Virtual Forest Clearcutting: Modeling the Effects of Forest Harvest on Streamflow through Parameter Regionalization

    NASA Astrophysics Data System (ADS)

    Teutschbein, Claudia; Grabs, Thomas; Karlsen, Reinert; Laudon, Hjalmar; Bishop, Kevin

    2015-04-01

    Forests provide a number of important water-related ecosystem services and play an important role as controllers of the hydrologic cycle. Catchment experiments have found evidence that changes in forest cover can alter streamflow regimes. But can effects of forest harvest on streamflow regimes also be predicted with help of a modeling approach? In this contribution we demonstrate that parameter regionalization of a hydrological model is a promising method to perform virtual forest clearcutting, because it relates the calibrated model parameters to a catchment's physical properties. We analyzed the hydrological behavior of 14 partially-nested catchments in Northern Sweden with slightly different topography, land cover, size and geology. For each catchment, the conceptual hydrological HBV light model was calibrated and parameters sensitive to forest cover percentage were identified. By modifying these parameters according to their statistical relationships with forest cover, we seek to virtually harvest the forest in each catchment and to simulate the consequences for streamflow. This approach can be easily applied to other regions or up-scaled to larger areas and, thus, theoretically allows the prediction of forest clearcutting effects on streamflow.

  10. Empirical relations between catchment characteristics and discharge patterns in Sweden

    NASA Astrophysics Data System (ADS)

    Lindström, G.; Dahné, J.; Arheimer, B.

    2012-04-01

    In hydrological modelling it is often assumed that catchment characteristics, such as soil type, vegetation, land-use, slope, altitude and climate influence both the magnitude and dynamics of the water discharge characteristics. This presentation demonstrates an inter-site comparison on similarities and dissimilarities in hydrological response from Swedish unregulated catchments with an area less than 2000 km2. Observed daily time-series for about 20 years from 198 sites were analysed to search for and quantify statistical relationships between catchment characteristics and flow characteristics. A number of flow characteristics were calculated, such as the mean, mean annual maximum, peakiness, skewness and percentiles. The catchments were grouped dependent on catchment characteristics (for example >80% forest). The differences between the discharges from different catchment types were analysed both graphically and statistically. A T-test was performed to see if the mean value for the flow characteristics was significantly different from the rest of the catchments. Following the t-test, a set of box-whisker diagrams were made for visual inspection of the results. The results showed that lake percentage is the most important catchment characteristic for most of the flow characteristics. The effect of lakes was therefore treated separately. For lake-free basins soil type was in general more important than land-use. For instance, coarse soils exhibit a sustained base flow, whereas thin soils and bare rock are characterised by peak flows with short duration. Finally, the presentation will give some examples on how the retrieved empirical information was included in a national modelling approach to simulate spatial variability in Swedish water discharge patterns.