Science.gov

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.

  2. 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

  3. Streamflow variation of forest covered catchments

    NASA Astrophysics Data System (ADS)

    Gribovszki, Z.; Kalicz, P.; Kucsara, M.

    2003-04-01

    Rainfall concentration and runoff, otherwise rainfall-runoff processes, which cause river water discharge fluctuation, is one of the basic questions of hydrology. Several social-economy demands have a strong connection with small or bigger rivers from the point of view both quantity and quality of the water. Gratification or consideration of these demands is complicated substantially that we have still poor knowledge about our stream-flow regime. Water resources mainly stem from upper watersheds. These upper watersheds are the basis of the water concentration process; therefore we have to improve our knowledge about hydrological processes coming up in these territories. In this article we present runoff regime of two small catchments on the basis of one year data. Both catchments have a similar magnitude 0.6 and 0.9 km^2. We have been analyzed in detail some hydrological elements: features of rainfall, discharge, rainfall induced flooding waves and basic discharge in rainless periods. Variances of these parameters have been analyzed in relation to catchments surface, vegetation coverage and forest management. Result data set well enforce our knowledge about small catchments hydrological processes. On the basis of these fundamentals we can plan more established the management of these lands (forest practices, civil engineering works, and usage of natural water resources).

  4. [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

  5. [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.

  6. [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.

  7. [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

  8. 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...

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Time series of long-term annual fluxes in the streamwater of nine forest catchments from the Swedish environmental monitoring program (PMK 5).

    PubMed

    Fölster, Jens; Bishop, Kevin; Krám, Pavel; Kvarnäs, Hans; Wilander, Anders

    2003-07-01

    International cooperation has contributed to major declines in SO(2) emission and S deposition during the last two decades in Europe. The chemical recovery from already anthropogenically acidified sites however, has been slow. In the present paper, long-term trends of chemical fluxes from nine selected forested reference catchments were studied, to detect recovery from acidification and leaching of S and base cations (BC). A decline in S deposition resulted in a decreased flux of non-marine sulfate (SO(4)*) in seven of nine streams, with statistically significant changes in four. The two cases with slight increases in SO(4)* flux resulted from increasing water flow. The SO(4)* decrease was followed by a recovery from acidification in terms of increased ANC flux in those sites in southern Sweden that were chronically acidified. The recovery was probably slowed down by leaching of SO(4) from the soil and a decrease in the flux of BC. A better understanding of the processes for leaching of SO(4) and BC is needed in order to quantify the need for further restrictions of sulfur emissions to allow a long term recovery of acidified catchments. The flux calculations available from small catchments such as those in this study, are of value for that understanding.

  14. 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

  15. 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.

  16. 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

  17. 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

  18. pH sensitivity of Swedish forest streams related to catchment characteristics and geographical location - Implications for forest bioenergy harvest and ash return

    NASA Astrophysics Data System (ADS)

    Ågren, Anneli; Löfgren, Stefan

    2013-04-01

    Whole-tree harvesting acidifies forest soils more than conventional harvest of stems. There is concern that this excess acidification will also affect surface waters and counteract the well-documented recovery from acid deposition in streams and lakes. Here we present a first attempt to identify the landscape types within Sweden where the streams are most sensitive to acidification and potentially in need of protection from excessive biomass harvest or countermeasures such as ash application. Conservative estimates indicate that forest slash must be harvested from >30 ha to produce the amount of ash needed to restore 1 ha acidified surface water. This highlights the need for careful planning of where ash should be distributed. Streams with a high pH are well buffered by the bicarbonate system and not sensitive to a potential pH decline. Streams with a low pH are also well buffered by dissolved organic carbon and aluminum and are not likely affected by bioenergy harvest. However, streams in the intermediate pH range (5-6.2) are potentially sensitive to acidification from excess base cation removal due to whole-tree harvesting. In such streams a small change in acid neutralizing capacity (ANC) can change pH dramatically. The pH sensitivity of 218 streams in different regions (northern, central, southern, and southwest Sweden) was defined from stream water pH and related to catchment characteristics and stream water acid-base chemistry. At the national level, catchments with till soils and a large proportion of forested wetlands formed the most pH sensitive areas. Because of regional variability in acidification history, amount and distribution of quaternary deposits, vegetation cover, etc. pH sensitivity was determined by different landscape elements in different regions. For example, in northern Sweden streams draining forest mires were the most pH sensitive streams. The patchy spatial distribution of this landscape type, makes it difficult from an administrative

  19. 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...

  20. 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...

  1. 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...

  2. Predicting export of dissolved organic carbon from forested catchments in glaciated landscapes with shallow soils

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Beall, F. D.; Clair, T. A.; Dillon, P. J.; Hesslein, R. H.

    2008-12-01

    This study presents a simple model of dissolved organic carbon (DOC) loading to surface waters that is applicable to headwater catchments in forested regions on glaciated landscapes. Average annual DOC export was highly variable among the 33 experimental catchments along an east-west transect, ranging from 0.90 to 13.74 g C/m2/a. It was hypothesized that the proportion of wetlands within the catchments would explain the majority of variation in average annual DOC export. To test this hypothesis, digital terrain analysis was used to derive wetlands automatically under both open and closed forest canopies by identifying the probability of a grid cell being a depression and/or flat. Using a 10 m digital elevation model (DEM) derived from readily available sources, the proportion of wetlands explained 63% of the variance in average annual DOC export among the 33 experimental catchments. Inclusion of regional climatic indicators, including the number of growing degree days (with a base of 10°C) and the runoff coefficient, increased explanation of variance from 63% to 89%, once catchments with lakes (>5% of catchment area) adjacent to the catchment outlets were removed. This study shows that DOC export can be predicted accurately from headwater catchments in forested regions on glaciated landscapes using a simple model based on the proportion of wetlands and easily calculated climatic variables.

  3. 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.

  4. 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

  5. Coupled forest growth-hydrology modelling as an instrument for the assessment of effects of forest management on hydrology in forested catchments

    NASA Astrophysics Data System (ADS)

    Sutmöller, J.; Hentschel, S.; Hansen, J.; Meesenburg, H.

    2011-03-01

    The type and intensity of forest management directly influences regional catchment hydrology. Future forest management must optimise the effects of its practices to achieve sustainable management. With scenario analysis of forestry practices, the effects of different forest utilisation strategies on the hydrology of forested catchments can be temporally and spatially quantified. The approach adopted in this study necessitated the development of an interactive system for the spatially distributed modelling of hydrology in relation to forest stand development. Consequently, a forest growth model was used to simulate stand development assuming various forest management activities. Selected simulated forest growth parameters were entered into the hydrological model to simulate water fluxes under different conditions of forest structure. The approach enables the spatially differentiated quantification of changes in the water regime (e.g. increased evapotranspiration). The results of hydrological simulations in the study area, the Oker catchment (northern Harz Mountains), show that forests contribute to the protection of water systems because they have a balancing effect on the hydrological regime. As scenario simulations also suggest, however, forestry practices can also lead to substantial changes in water budgets of forested catchments. The preservation of the hydrological services of forests requires a sustainable and long-term forest conversion on the basis of current management directives for near natural silviculture. Management strategies on basis of moderate harvesting regimes are preferred because of their limited impact on the water budget.

  6. Sulphate, nitrogen and base cation budgets at 21 forested catchments in Canada, the United States and Europe.

    PubMed

    Watmough, Shaun A; Aherne, Julian; Alewell, Christine; Arp, Paul; Bailey, Scott; Clair, Tom; Dillon, Peter; Duchesne, Louis; Eimers, Catherine; Fernandez, Ivan; Foster, Neil; Larssen, Thorjorn; Miller, Eric; Mitchell, Myron; Page, Stephen

    2005-10-01

    To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s average) for sulphate (SO(4)), inorganic nitrogen (NO(3)-N; NH(4)-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada, the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more than 9 years of data were available (14 regions, 17 sites). Annual average SO(4) deposition during the 1990s ranged between 7.3 and 28.4 kg ha(-1) per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha(-1) per year, of which 41-67% was nitrate (NO(3)-N). Over the period of record, SO(4) concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO(4) in runoff decreased at 14/17 catchments. In contrast, NO(3)-N concentrations in deposition decreased in only 1/14 regions, while NH(4)-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH(4)-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively, which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at 18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31-100%; median 94%) was retained in the catchments, although there was a tendency for greater NO(3)-N leaching at sites receiving higher (<7 kg ha(-1) per year) bulk inorganic N

  7. Sulphate, nitrogen and base cation budgets at 21 forested catchments in Canada, the United States and Europe.

    PubMed

    Watmough, Shaun A; Aherne, Julian; Alewell, Christine; Arp, Paul; Bailey, Scott; Clair, Tom; Dillon, Peter; Duchesne, Louis; Eimers, Catherine; Fernandez, Ivan; Foster, Neil; Larssen, Thorjorn; Miller, Eric; Mitchell, Myron; Page, Stephen

    2005-10-01

    To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s average) for sulphate (SO(4)), inorganic nitrogen (NO(3)-N; NH(4)-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada, the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more than 9 years of data were available (14 regions, 17 sites). Annual average SO(4) deposition during the 1990s ranged between 7.3 and 28.4 kg ha(-1) per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha(-1) per year, of which 41-67% was nitrate (NO(3)-N). Over the period of record, SO(4) concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO(4) in runoff decreased at 14/17 catchments. In contrast, NO(3)-N concentrations in deposition decreased in only 1/14 regions, while NH(4)-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH(4)-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively, which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at 18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31-100%; median 94%) was retained in the catchments, although there was a tendency for greater NO(3)-N leaching at sites receiving higher (<7 kg ha(-1) per year) bulk inorganic N

  8. 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

  9. Isotopic signals of denitrification in a northern hardwood forested catchment

    NASA Astrophysics Data System (ADS)

    Wexler, Sarah; Goodale, Christine

    2013-04-01

    significance and spatial variability of denitrification in environments with low levels of nitrate, represented by this northern hardwood forested catchment.

  10. Comparison of the characteristics of storm runoff and long-term discharge between a natural forest catchment and a complicated natural-artificial catchment in Japan

    NASA Astrophysics Data System (ADS)

    Hong, Lin

    2010-05-01

    Agricultural activities such as land reclamation, crop production, pesticide and fertilizer application, irrigation and drainage will cause impact on the hydrological cycle and water quality of the catchment. In this study, the hydrological characteristics during storm runoff and long-term discharges of a complicated natural-artificial terraced paddy field catchment, which is composed of natural forest (73% of the area) and terraced paddy field (27% of the area), are compared with those of a natural forest catchment. According to the theory of the rational formula, peak discharge is given as: Qp=fp rtpA/3.6 (1) where, Qp is peak discharge, in m3/s; fp is the runoff coefficient, for the natural forest catchment and the complicated natural-artificial Catchment, fp=0.60 and 0.55, respectively; rtp is the average intensity of actual rainfall during tp, in mm/h; tp is concentration time, in min; A is the area of the catchment, in km2. According to literature, tp is given as: tp=CA0.22(re)-0.35 (2) where, C is a coefficient depending on land use, for the natural forest catchment and the complicated natural-artificial catchment and natural forest catchment, C=107 and 175, respectively; re is effective rainfall intensity and it is equal to the specific peak discharge of a storm, mm/h. From the comprehensive effects of runoff coefficient and concentration time on peak discharge, we find that the peak discharge of the complicated natural-artificial catchment is about 1.5 times as much as that of the natural forest catchment. Analyses of the recession limbs for various storms in the 2 catchments reveals that the storm runoff decreases with an exponential decay constant of 0.024 h-1 from several hours after rainfall to one or two days later, and then continues to decay with a decay constant of 0.011 h-1. By analysis of the relationship between percolation and duration of percolation in the 2 catchments we find that a linear relationship between the percolation and the duration

  11. 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

  12. Sediment transport in steep forested catchments: the role of disturbance and scale

    NASA Astrophysics Data System (ADS)

    Hancock, Greg; Hugo, James; Webb, Ashley

    2016-04-01

    Sediment loads (both bedload and suspended sediment) are difficult to measure due to the time and equipment needed. However such data is needed to understand overall sediment transport rates, landscape evolution, effect of human disturbance as well as patterns and temporal response. There is a dearth of such data sets globally let along for Australia. Here we present the findings from 8 steep slope forested catchments dominated by headwater streams (size range 15-100 hectares) in south-eastern Australia where both bedload and suspended load have been measured over multiple years. The results demonstrate that suspended load is the dominant component. There appears to be no consistent suspended to bedload ratio for the catchments. The suspended sediment to bedload ratio appears to be catchment specific. There was no relationship between total load (or bedload/suspended load) and average catchment slope, stream length, shape or any geomorphic descriptor. Again this appears to be catchment specific. However catchment total load was found to be significantly related to catchment area and demonstrates strong log-log linear behaviour. Comparing these total loads with total load data from a nearby larger catchments (100km2 to 1000km2) demonstrates that there is a significant scaling relationship across all catchment sizes in this region. The scaling relationships found here are similar to those found globally and provide a unique insight into an understudied system. The data also provides the ability to assess sediment transport models and their reliability across different scales.

  13. Pools and fluxes of mercury and methylmercury in two forested catchments in Germany.

    PubMed

    Schwesig, D; Matzner, E

    2000-10-01

    Mercury (Hg) and methylmercury (CH3Hg+) are global pollutants, but little information is available on rates of atmospheric input, distribution and mobility in soils and catchments of central Europe. The objectives of this study were to investigate input and output fluxes of these compounds in a deciduous and a coniferous catchment in NE Bavaria (Germany), and to estimate pools and mobility of total Hg (Hgtot) and CH3Hg+ at the catchment scale. Bulk precipitation, throughfall, litterfall and runoff were collected biweekly from April 1998 to April 1999. Several soil profiles were sampled to estimate pools of Hg compounds in the catchments. In both catchments highest contents of Hgtot were found in the Oa layer of the forest floor (up to 500 ng g(-1)) and the soil storage of Hgtot calculated for a soil depth of 60 cm was approximately 890 g ha(-1) in the coniferous and 190 g ha(-1) in the deciduous catchment. Highest contents of CH3Hg+ in upland soils were observed in the Oi layer of the forest floor, and soil storage of CH3Hg+ was 4.35 g ha(-1) in the coniferous and 0.59 g ha(-1) in the deciduous catchment. The annual total deposition of Hgtot (total deposition not measured directly but calculated from throughfall and litterfall) was 541 mg ha(-1) year(-1) in the coniferous and 618 mg ha(-1) year(-1) in the deciduous catchment. Total deposition rates of CH3Hg+ were 3.5 and 2.6 mg ha(-1) year(-1). The contribution of litterfall to the total deposition of Hgtot and CH3Hg+ was 55% in the deciduous catchment. In the coniferous catchment, the contribution of litterfall to total deposition was only 29% for Hgtot, but 55% for CH3Hg+. By far the largest proportion of the deposited CH3Hg+ and Hgtot remained in the catchments (85% in the coniferous, 95% in the deciduous). As compared to remote Swedish catchments, deposition and output via runoff of Hgtot, were higher, but deposition and output of CH3Hg+ were lower in our catchments. In contrast to other studies, the annual

  14. Deposition and leaching of sulfur, nitrogen and calcium in four forested catchments in China: implications for acidification.

    PubMed

    Larssen, Thorjørn; Duan, Lei; Mulder, Jan

    2011-02-15

    Here we present the first detailed study on fluxes of sulfur (S), nitrogen (N), and major cations in Chinese subtropical forest catchments. Data are from four study sites, differing in inputs of atmospheric pollutants and sensitivity to acidification. Results show important differences from most sites in North America and Europe. Dry deposition of S, N, and calcium (Ca) is considerably larger than wet deposition in most cases causing deposition fluxes ranging from moderate to very high, both for acidifying compounds (S deposition 1.5-10.5 kiloequivalents per hectare and year (keq ha(-1) yr(-1)); N deposition 0.4 to 2.5 keq ha(-1) yr(-1)) and for alkaline compounds (Ca deposition 0.8 to 5.7 keq ha(-1) yr(-1)). More than half of the input of acidity is neutralized by alkalinity associated with Ca deposition. Furthermore, the retention of incoming S and N is small in the soil root zone, but considerable in the deeper soils or riparian zone. Drainage water from the root zone of the soils at the two sites with the highest deposition show pronounced acidification. For the two sites with moderate deposition inputs, the root zones are retaining some of the incoming S and buffer some of the incoming acidity. The subsoils and the riparian zonesare strong sinks for N, S, and Ca. This is associated with substantial acid neutralization at all sites. These features are of major importance for the understanding of the long-term effects of acidification in China.

  15. 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.

  16. 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.

  17. [Research progress on unsaturated and saturated soil water movement in forest catchments].

    PubMed

    Yang, Hong; Pei, Tiefan

    2005-09-01

    This paper reviewed the studies on the movement ways, i. e., infiltration, phreatic evaporation, ground water recharge and interflow, of unsaturated and saturated soil water in forest catchments, and introduced the present advances in soil hydraulic parameters, including soil water characteristic curve, and unsaturated and saturated soil hydraulic conductivity. Research directions in the future were also proposed.

  18. 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,...

  19. 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...

  20. Natural inactivation of phosphorus by aluminum in atmospherically acidified water bodies.

    PubMed

    Kopácek, J; Ulrich, K U; Hejzlar, J; Borovec, J; Stuchlik, E

    2001-11-01

    Atmospheric acidification of catchment-lake ecosystems may provide natural conditions for the in-lake control of P cycling. This process is based on the elevated transport of aluminum from acidified soils and its subsequent precipitation in the water body and is described for strongly acidified forest lakes, acidified and circumneutral reservoirs, and a moderately acidified alpine lake. In water bodies with episodically or permanently acidified inflows a pH gradient develops between lake water and tributaries due to: (i) neutralization of acidic inflows after mixing with waters with undepleted carbonate buffering system, and/or (ii) the in-lake alkalinity generation dominated by biochemical removal of NO3- and SO4(2-). With the pH increasing towards neutrality, ionic Al species hydrolyze and form colloidal Al hydroxides (Al(part)) with large specific surfaces and strong ability to bind orthophosphate from the liquid phase. Moreover, Alpart settles and increases the P sorption capacity of the sediment. The presence of Al(part) on the bottom reduces orthophosphate release from sediments after its liberation from ferric oxyhydroxides during anoxia because Al(part) is not sensitive to redox changes. Consequently, the natural in-lake P inactivation may be expected in any water body with elevated Al input and a pH gradient between its inlet and outlet.

  1. Fluxes and reservoirs of trichloroacetic acid at a forest and moorland catchment.

    PubMed

    Stidson, R T; Dickey, C A; Cape, J N; Heal, K V; Heal, M R

    2004-03-15

    The concentrations and input/output fluxes of trichloroacetic acid (TCA) were measured in all relevant media for one year at a 0.86 km2 upland conifer plantation and moorland catchment in SW Scotland (n > 380 separate samples analyzed). Annual wet precipitation to the catchment was 2.5 and 0.4 m for rain and cloud, respectively. TCA input to the catchment for the year was 2100 g, predominantly in rainwater (86%), with additional input via cloudwater (13%) and gas plus particle dry deposition (1%). There were no seasonal trends in TCA deposition, and cloudwater concentration was not enhanced over rainwater. TCA in precipitation exceeded concentrations estimated using currently accepted routes of gas-phase oxidation from anthropogenic chlorinated hydrocarbon precursors, in agreement with previous studies. Export of TCA from the catchment in streamwater totalled 1970 g for the year of study. The TCA concentration in streamwater at outflow (median 1.2 microg L(-1)) was significantly greater than that before the stream had passed through the conifer plantation. To well-within measurement uncertainties, the catchment is currently at steady-state with respect to TCA input/output. The catchment reservoir of TCA was dominated by soils (approximately 90%), with the remainder distributed in forest litter (approximately 9%), forest branchwood and stemwood (approximately 0.7%), forest foliage (approximately 0.5%), and moorland foliage (approximately 0.1%). Although TCA is clearly taken up into foliage, which consequently may be important for the vegetation, this was a relatively minor process for TCA at the catchment scale. If it is assumed, on the basis of laboratory extraction experiments, that only approximately 20% of "whole soil" TCA measured in this work was water extractable, then total mass of TCA in the catchment is reduced from approximately 13 to approximately 3.5 kg. Comparing the latter value with the annual flux yields an average steady-state residence time for

  2. Fluxes and reservoirs of trichloroacetic acid at a forest and moorland catchment.

    PubMed

    Stidson, R T; Dickey, C A; Cape, J N; Heal, K V; Heal, M R

    2004-03-15

    The concentrations and input/output fluxes of trichloroacetic acid (TCA) were measured in all relevant media for one year at a 0.86 km2 upland conifer plantation and moorland catchment in SW Scotland (n > 380 separate samples analyzed). Annual wet precipitation to the catchment was 2.5 and 0.4 m for rain and cloud, respectively. TCA input to the catchment for the year was 2100 g, predominantly in rainwater (86%), with additional input via cloudwater (13%) and gas plus particle dry deposition (1%). There were no seasonal trends in TCA deposition, and cloudwater concentration was not enhanced over rainwater. TCA in precipitation exceeded concentrations estimated using currently accepted routes of gas-phase oxidation from anthropogenic chlorinated hydrocarbon precursors, in agreement with previous studies. Export of TCA from the catchment in streamwater totalled 1970 g for the year of study. The TCA concentration in streamwater at outflow (median 1.2 microg L(-1)) was significantly greater than that before the stream had passed through the conifer plantation. To well-within measurement uncertainties, the catchment is currently at steady-state with respect to TCA input/output. The catchment reservoir of TCA was dominated by soils (approximately 90%), with the remainder distributed in forest litter (approximately 9%), forest branchwood and stemwood (approximately 0.7%), forest foliage (approximately 0.5%), and moorland foliage (approximately 0.1%). Although TCA is clearly taken up into foliage, which consequently may be important for the vegetation, this was a relatively minor process for TCA at the catchment scale. If it is assumed, on the basis of laboratory extraction experiments, that only approximately 20% of "whole soil" TCA measured in this work was water extractable, then total mass of TCA in the catchment is reduced from approximately 13 to approximately 3.5 kg. Comparing the latter value with the annual flux yields an average steady-state residence time for

  3. 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

  4. 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

  5. A Comparison of Runoff Pathways and Nutrient Export in Small Tropical Forest Catchments

    NASA Astrophysics Data System (ADS)

    Hamann, H. B.; Stallard, R. F.; Pullen, N. H.

    2004-12-01

    The Center for Tropical Forest Research (CTFS), a program of the Smithsonian Tropical Research Institute (STRI), has coordinated a global network of 17 tropical forest dynamics plots of approximately 50 hectares in order to collect baseline information and to monitor forest changes. Missing from most past studies of these plots is an integrated soil hydrology and water chemistry component. To fill this gap, we have developed and are testing rapid assessment methods to measure soil and hydrological properties for tropical forest catchments. This assessment includes gaging and sampling first to third order headwater streams with high frequency over several storm events within a 2-4 week period. Detailed flow separations enable us to test Elsenbeer's (2001) functional classification continuum for tropical soils and allow us to test the hypothesis that forest sites with greater overland flow experience greater nutrient loss during storm events. Data from a storm event for the steep Lutz Creek Catchment on Barro Colorado Island, Panama in September 1990 demonstrate that Na+ and Si, typical of most solutes, decrease in concentration with increasing discharge. In contrast, the nutrients, K+ and NO3- increase in concentration with increasing discharge. Results from a 20 ha catchment in Yasuni National Park, Ecuador from November 2003 show a similar pattern during several small events on relatively impermeable soils. Data collected from a more permeable 20 ha catchment in Lambir Hills National Park, Malaysia in July 2004 also show nutrient export, but suggest that rainfall amount, intensity and duration may play a large role in the magnitude of nutrient concentrations. Elsenbeer, H., 2001. Hydrological flowpaths in tropical rain forest soilscapes-a review. Hydrological Processes, 15: 1751-1759.

  6. 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.

  7. Estimating Catchment-Scale Snowpack Variability in Complex Forested Terrain, Valles Caldera National Preserve, NM

    NASA Astrophysics Data System (ADS)

    Harpold, A. A.; Brooks, P. D.; Biederman, J. A.; Swetnam, T.

    2011-12-01

    Difficulty estimating snowpack variability across complex forested terrain currently hinders the prediction of water resources in the semi-arid Southwestern U.S. Catchment-scale estimates of snowpack variability are necessary for addressing ecological, hydrological, and water resources issues, but are often interpolated from a small number of point-scale observations. In this study, we used LiDAR-derived distributed datasets to investigate how elevation, aspect, topography, and vegetation interact to control catchment-scale snowpack variability. The study area is the Redondo massif in the Valles Caldera National Preserve, NM, a resurgent dome that varies from 2500 to 3430 m and drains from all aspects. Mean LiDAR-derived snow depths from four catchments (2.2 to 3.4 km^2) draining different aspects of the Redondo massif varied by 30%, despite similar mean elevations and mixed conifer forest cover. To better quantify this variability in snow depths we performed a multiple linear regression (MLR) at a 7.3 by 7.3 km study area (5 x 106 snow depth measurements) comprising the four catchments. The MLR showed that elevation explained 45% of the variability in snow depths across the study area, aspect explained 18% (dominated by N-S aspect), and vegetation 2% (canopy density and height). This linear relationship was not transferable to the catchment-scale however, where additional MLR analyses showed the influence of aspect and elevation differed between the catchments. The strong influence of North-South aspect in most catchments indicated that the solar radiation is an important control on snow depth variability. To explore the role of solar radiation, a model was used to generate winter solar forcing index (SFI) values based on the local and remote topography. The SFI was able to explain a large amount of snow depth variability in areas with similar elevation and aspect. Finally, the SFI was modified to include the effects of shading from vegetation (in and out of

  8. Deposition and leaching of sulfur, nitrogen and calcium in four forested catchments in China: implications for acidification.

    PubMed

    Larssen, Thorjørn; Duan, Lei; Mulder, Jan

    2011-02-15

    Here we present the first detailed study on fluxes of sulfur (S), nitrogen (N), and major cations in Chinese subtropical forest catchments. Data are from four study sites, differing in inputs of atmospheric pollutants and sensitivity to acidification. Results show important differences from most sites in North America and Europe. Dry deposition of S, N, and calcium (Ca) is considerably larger than wet deposition in most cases causing deposition fluxes ranging from moderate to very high, both for acidifying compounds (S deposition 1.5-10.5 kiloequivalents per hectare and year (keq ha(-1) yr(-1)); N deposition 0.4 to 2.5 keq ha(-1) yr(-1)) and for alkaline compounds (Ca deposition 0.8 to 5.7 keq ha(-1) yr(-1)). More than half of the input of acidity is neutralized by alkalinity associated with Ca deposition. Furthermore, the retention of incoming S and N is small in the soil root zone, but considerable in the deeper soils or riparian zone. Drainage water from the root zone of the soils at the two sites with the highest deposition show pronounced acidification. For the two sites with moderate deposition inputs, the root zones are retaining some of the incoming S and buffer some of the incoming acidity. The subsoils and the riparian zonesare strong sinks for N, S, and Ca. This is associated with substantial acid neutralization at all sites. These features are of major importance for the understanding of the long-term effects of acidification in China. PMID:21250675

  9. 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.

  10. Chlorine And Chloroform Transport In A Small Forested Catchment

    NASA Astrophysics Data System (ADS)

    Svensson, T.

    2006-12-01

    It is generally known that chlorine compounds are ubiquitous in the environment. In recent years, researchers have concluded that chlorine is part of a biogeochemical cycle in soil involving an interaction between chloride and organic-matter-bound chlorine. Even though there is indisputable evidence that organochlorines are formed naturally, there are actually few simultaneous field measurements of organochlorines and chloride. Previously stipulated conclusions with respect to underlying processes and transport estimates have thus been deduced from rather few concentration measurements. The on-site variation organic-matter-bound chlorine, chloroform and chloride runoff water were observed and input and output fluxes estimated over a 2-yr period in a small coniferous catchment (0.22 km2) in southeast Sweden. The results show that the transport is dominated by chloride whereas the storage in soil is dominated by organic-matter-bound chlorine and that the storage is far much larger than the transport. Still, input and output is nearly in balance for all investigated chlorine species. It is interesting to note that these observations resemble observations made for carbon, nitrogen and sulphur; i.e. a large storage, small transport, complex biogeochemical cycling processes at hand but still close to steady state conditions with respect to output- input balances. It appears as if topsoil acts as a sink for chloride, while deeper soil acts as a source of chloride. Furthermore, to the best of our knowledge, neither flux estimates nor mass balances have previously been made for chloroform on a catchment scale, nor have data regarding natural runoff variation with time been gathered. Concentrations of chloroform in runoff were found to be generally high during wet periods, such as spring, but also peaked during summer rain events. The observed pattern suggests that chloroform is formed in surface soil layers and transported to the outlet under high-flow conditions and during

  11. [Research advances in dynamic mechanism and its simulation of eco-hydrological process in forest catchment].

    PubMed

    Diao, Yiwei; Pei, Tiefan

    2004-12-01

    Hydrological process is the key link between climatic fluctuations and ecologic dynamics of forests at spatial and temporal scales. To some extent, global climate change and large-scale human's activities will impact the spatial-temporal changes of eco-hydrological process in forest catchments in the future. Therefore, researches on the dynamic mechanism of eco-hydrological processes in forest catchments play a crucial role in understanding and controlling the rational use of ecological resources, resuming regional ecology, and sustainable development in economy. This paper described the interception, evapotranspiration and rainfall-runoff of forest ecological system and their effects on hydrological process. The spatial structure of soil moisture and its evolution with time were also the cause and consequence of forest. The spatial-temporal interaction between hydrologic and ecologic dynamics, the application of distributed hydrological model, and the eco-hydrological dynamics and cybernetics of forest would be the most exciting frontiers of the relative researches in the future. PMID:15825459

  12. 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

  13. 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...

  14. 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).

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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

  3. Export of nitrogen from catchments within a temperate forest: Evidence for a unifying mechanism regulated by variable source area dynamics

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Band, L. E.

    1998-11-01

    Considerable variation in the export of dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON) was observed among catchments located within an old-growth sugar maple forest in central Ontario. Although discharge was a strong predictor of N-export, rates of export were variable for each catchment, ranging from -50% to +50% from the catchment-average response for DIN and -25% to +25% from the catchment-average response for DON. Among the catchments, a unifying flushing behavior was apparent for NO3--N, the dominant form of DIN in the discharge waters, providing a basis for explaining the variation in the export of DIN. Flushing occurs when a water table rises to the soil surface with subsequent mobilization of nutrients stored near or at the soil surface to surface waters. Catchment-specific flushing behaviors were captured in "flushing" characteristic time constants, defined as the time interval required for a decline in N concentrations in discharge waters toe-l (37%) of their initial concentration. Variation in flushing behavior was linked to variation in N export; catchments with short flushing times (interpreted as catchments with source areas that are less variable) were observed to export less N than catchments with long flushing times (source areas that are more variable). A hypothesis was formulated in which catchment topography and its influence on variable source area dynamics accounts for variation in flushing behavior, hence variation in the export of NO3--N among the catchments. The implication of this hypothesis is that to predict accurately the export of NO3--N from catchments within a landscape, we need first to consider the influence of the topographic complexity of the catchments. Our understanding of the mechanisms of processing and export of DON is not sufficient for accurate prediction at this point, highlighting the need for additional research on DON.

  4. The hydrochemistry of plantation spruce forest catchments with brown earth soils, Vyrnwy in mid-Wales

    NASA Astrophysics Data System (ADS)

    Neal, C.; Reynolds, B.; Neal, M.; Williams, B.

    At Vyrnwy, in mid-Wales, a study of the hydrogeochemistry of two small spruce forested catchments, one a control and one felled midway through the study, shows a classic picture of rainfall inputs damped by the catchment and stream waters the chemistry of which varies as functions of flow and particularly of the supply of more acidic and aluminium-bearing soil water and of more basic and calcic ground waters from the zone where weathering reactions with the bedrock are high. The ground waters are most alkaline although pH may be depressed due to high dissolved carbon dioxide pressures. Nitrate concentrations increase in the first year after felling and decrease thereafter below those of the control. Water quality changes due to the dominant hydrogeochemical processes show that harvesting raises no significant water quality management issues.

  5. Nutrient export from catchments on forested landscapes reveals complex nonstationary and stationary climate signals

    NASA Astrophysics Data System (ADS)

    Mengistu, Samson G.; Quick, Christopher G.; Creed, Irena F.

    2013-06-01

    Headwater catchment hydrology and biogeochemistry are influenced by climate, including linear trends (nonstationary signals) and climate oscillations (stationary signals). We used an analytical framework to detect nonstationary and stationary signals in yearly time series of nutrient export [dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate (NO3--N), and total dissolved phosphorus (TDP)] in forested headwater catchments with differential water loading and water storage potential at the Turkey Lakes Watershed in Ontario, Canada. We tested the hypotheses that (1) climate has nonstationary and stationary effects on nutrient export, the combination of which explains most of the variation in nutrient export; (2) more metabolically active nutrients (e.g., DON, NO3--N, and TDP) are more sensitive to these signals; and (3) catchments with relatively low water loading and water storage capacity are more sensitive to these signals. Both nonstationary and stationary signals were identified, and the combination of both explained the majority of the variation in nutrient export data. More variation was explained in more labile nutrients (DON, NO3--N, and TDP), which were also more sensitive to climate signals. The catchment with low-water storage potential and low water loading was most sensitive to nonstationary and stationary climatic oscillations, suggesting that these hydrologic features are characteristic of the most effective sentinels of climate change. The observed complex links between climate change, climatic oscillations, and water nutrient fluxes in headwater catchments suggest that climate may have considerable influence on the productivity and biodiversity of surface waters, in addition to other drivers such as atmospheric pollution.

  6. 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

  7. Sediment source fingerprinting to quantify fine sediment sources in forested catchments, Chile.

    NASA Astrophysics Data System (ADS)

    Schuller, P.; Walling, D. E.; Iroume, A.; Castillo, A.; Quilodran, C.

    2012-04-01

    A study to improve the understanding of the primary sediment sources and transfer pathways in catchments disturbed following forest plantation harvesting is being undertaken in South-Central Chile. The study focuses on two sets of paired experimental catchments (treatment and control), located about 400 km apart, with similar soil type but contrasting mean annual rainfall: Nacimiento (1,200 mm year-1) and Los Ulmos (2,500 mm year-1). Sediment source fingerprinting techniques are being used to document the primary fine sediment sources. In each catchment, three potential sediment sources were defined: clearcut slopes (Z1), forest roads (Z2) and the stream channel (Z3). In each catchment, multiple representative composite samples of the different potential source materials were collected before harvest operations from the upper 1 cm layer in Z1, Z2, and from the channel bank and bed for Z3. A time-integrating trap sampler installed in the discharge monitoring station constructed at the outlet of each catchment has been used to collect samples of the suspended sediment and these have been supplemented by sediment collected from the weir pools. Total suspended sediment load is been quantified in the monitoring stations using discharge records and integrated water sampling. Caesium-137 (137Cs), excess lead-210 (210Pbex) and other sediment properties are being used as fingerprints. After air-drying, oven-drying at 40°C and disaggregation, both the source material samples and the sediment samples collected in the discharge monitoring stations were sieved through a 63-μm sieve and the <63-μm fractions were used for subsequent analyses. For radionuclide assay, the samples were sealed in Petri dishes and after 4 weeks the mass activity density (activity concentration) of 137Cs and 210Pbex was determined by gamma analysis, using an ORTEC extended range Ge detector of 53% relative efficiency. The 137Cs and 210Pbex activity and organic carbon (Corg) concentration associated

  8. 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.

  9. 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.

  10. Early Water Yield Effects of Conversion of Slopes of a Eucalypt Forest Catchment to Radiata Pine Plantation

    NASA Astrophysics Data System (ADS)

    Bren, L. J.; Papworth, M.

    1991-09-01

    Between 1975 and 1987 the water yield from three small, contiguous, forested catchments carrying similar vegetation in southeastern Australia was measured. These were located in humid, steep foothill areas subject to a major plantation program. At the project start all catchments carried mature, natural eucalypt forest. In their natural state the catchments exhibited similar annual hydrologic variation and water yields, with a pronounced low-flow period in summer and autumn, and high flows in winter and spring. One catchment was converted from native eucalypt forest to radiata pine by clearing, burning, and planting in December 1979. A 30-m buffer was retained along the stream. The treatment increased the water yield of the catchment by up to 3.5 ML ha-1, a 47% increase on average. The actual yield increase varied from year to year, and appeared to decline slowly with time from the conversion. Most of the increase was as increased storm flow in the early part of winter. The relation between the storm flow, causal rainfall, and antecedent flow did not appear to be changed by the treatment, suggesting that most of the storm flow response is attributable to increased catchment wetness at the end of the dry summer period.

  11. 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.

  12. 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

  13. Multifaceted value profiles of forest owner categories in south Sweden: the River Helge å catchment as a case study.

    PubMed

    Richnau, Gustav; Angelstam, Per; Valasiuk, Sviataslau; Zahvoyska, Lyudmyla; Axelsson, Robert; Elbakidze, Marine; Farley, Joshua; Jönsson, Ingemar; Soloviy, Ihor

    2013-03-01

    Forest landscapes provide benefits from a wide range of goods, function and intangible values. But what are different forest owner categories' profiles of economic use and non-use values? This study focuses on the complex forest ownership pattern of the River Helge å catchment including the Kristianstad Vattenrike Biosphere Reserve in southern Sweden. We made 89 telephone interviews with informants representing the four main forest owner categories. Our mapping included consumptive and non-consumptive direct use values, indirect use values, and non-use values such as natural and cultural heritage. While the value profiles of non-industrial forest land owners and municipalities included all value categories, the forest companies focused on wood production, and the Swedish Environmental Protection Agency on nature protection. We discuss the challenges of communicating different forest owners' economic value profiles among stakeholders, the need for a broader suite of forest management systems, and fora for collaborative planning.

  14. 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

  15. 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

  16. Aluminium concentrations in Swedish forest streams and co-variations with catchment characteristics.

    PubMed

    Löfgren, Stefan; Cory, Neil; Zetterberg, Therese

    2010-07-01

    The negative effects of elevated concentrations of inorganic aluminium on aquatic organisms are well documented. Acid deposition is often cited as a main driver behind the mobilisation and speciation of aluminium in soils and surface waters. In the study, we tested the hypothesis that sulphur deposition is the main driver for elevated concentrations of inorganic aluminium in 114 base poor, boreal Swedish streams. However, the deposition of anthropogenic sulphate has decreased substantially since it peaked in the 1970s, and at the current deposition levels, we hypothesise that local site parameters play an important role in determining vulnerability to elevated concentrations of inorganic aluminium in boreal stream waters. Presented here are the results of a principal components analysis of stream water chemistry, acid deposition data and local site variables, including forest composition and stem volume. It is shown that the concentrations of both organic and inorganic aluminium are not explained by either historical or current acid deposition, but are instead explained by a combination of local site characteristics. Sites with elevated concentrations of inorganic aluminium were characterised by small catchments (<500 ha) dominated by mature stands of Norway spruce with high stem volume. Using data from the Swedish National Forest Inventory the area of productive forest land in Sweden with a higher vulnerability for elevated inorganic aluminium concentrations in forests streams is approximately 1.5 million hectares or 7% of the total productive forest area; this is higher in the south of Sweden (10%) and lower in the north (2%). A better understanding of the effects of natural processes and forest management in controlling aquatic inorganic aluminium concentrations is therefore important in future discussions about measures against surface water acidification.

  17. 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.

  18. Aluminium concentrations in Swedish forest streams and co-variations with catchment characteristics.

    PubMed

    Löfgren, Stefan; Cory, Neil; Zetterberg, Therese

    2010-07-01

    The negative effects of elevated concentrations of inorganic aluminium on aquatic organisms are well documented. Acid deposition is often cited as a main driver behind the mobilisation and speciation of aluminium in soils and surface waters. In the study, we tested the hypothesis that sulphur deposition is the main driver for elevated concentrations of inorganic aluminium in 114 base poor, boreal Swedish streams. However, the deposition of anthropogenic sulphate has decreased substantially since it peaked in the 1970s, and at the current deposition levels, we hypothesise that local site parameters play an important role in determining vulnerability to elevated concentrations of inorganic aluminium in boreal stream waters. Presented here are the results of a principal components analysis of stream water chemistry, acid deposition data and local site variables, including forest composition and stem volume. It is shown that the concentrations of both organic and inorganic aluminium are not explained by either historical or current acid deposition, but are instead explained by a combination of local site characteristics. Sites with elevated concentrations of inorganic aluminium were characterised by small catchments (<500 ha) dominated by mature stands of Norway spruce with high stem volume. Using data from the Swedish National Forest Inventory the area of productive forest land in Sweden with a higher vulnerability for elevated inorganic aluminium concentrations in forests streams is approximately 1.5 million hectares or 7% of the total productive forest area; this is higher in the south of Sweden (10%) and lower in the north (2%). A better understanding of the effects of natural processes and forest management in controlling aquatic inorganic aluminium concentrations is therefore important in future discussions about measures against surface water acidification. PMID:19543997

  19. 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.

  20. Comparing erosion rates in burnt forests and agricultural fields for a mountain catchment in NW Iberia

    NASA Astrophysics Data System (ADS)

    Nunes, João Pedro; Marisa Santos, Juliana; Bernard-Jannin, Léonard; Keizer, Jan Jacob

    2013-04-01

    A large part of northwestern Iberia is nowadays covered by commercial forest plantations of eucalypts and maritime pines, which have partly replaced traditional agricultural land-uses. The humid Mediterranean climate, with mild wet winters and warm dry summers, creates favorable conditions for the occurrence of frequent and recurrent forest fires. Erosion rates in recently burnt areas have been the subject of numerous studies; however, there is still a lack of information on their relevance when compared with agricultural erosion rates, impairing a comprehensive assessment of the role of forests for soil protection. This study focuses on Macieira de Alcoba, head-water catchment in the Caramulo Mountain Range, north-central Portugal, with a mixture of agricultural fields (mostly a rotation between winter pastures and summer cereals) on the lower slopes and forest plantations (mostly eucalypts) on the upper slopes. Agricultural erosion in this catchment has been monitored since 2010; a forest fire in 2011 presented an opportunity to compare post-fire and agricultural erosion rates at nearby sites with comparable soil and climatic conditions. Erosion rates were monitored between 2010 and 2013 by repeated surveys of visible erosion features and, in particular, by mapping and measuring rills and gullies after important rainfall events. During the 2011/2012 hydrological year, erosion rates in the burnt forest were two orders of magnitude above those in agricultural fields, amounting to 17.6 and. 0.1 Mg ha-1, respectively. Rills were widespread in the burnt area, while in the agricultural area they were limited to a small number of fields with higher slope; these particular fields experienced an erosion rate of 2.3 Mg ha-1, still one order of magnitude lower than at the burnt forest site. The timing of the erosion features was also quite distinct for the burnt area and the agricultural fields. During the first nine months after the fire, rill formation was not observed in

  1. 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

  2. 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

  3. The role of forest in runoff generation in a suburban catchment

    NASA Astrophysics Data System (ADS)

    Ferreira, C. S. S.; Soares, D.; Soares, A. J. D.; Coelho, C. O. A.; Steenhuis, T. S.; Keizer, J. J.; Walsh, R. P. D.

    2012-04-01

    Forests play an important role in the water cycle, particularly through their influence on infiltration and evapotranspiration processes. Removing forest for urban growth will affect the hydrological cycle, but to what degree is not known. To improve the knowledge about the role of forest areas in the catchment surface runoff, a total of nine runoff plots (16m2) was installed in the three predominant woodland types found in the small Ribeira dos Covões catchment (620ha), located in a rapid urbanizing area in central Portugal. The three representative study sites comprised: (i) a dense eucalyptus stand on a sandy-loam soil overlying sandstone; (ii) a open eucalyptus stand dominated by dense shrub vegetation, also on a sandy-loam soil overlying sandstone; (iii) a Mediterranean oak stand on a loamy soil overlying limestone. The three plots at each site were bounded by metal sheets and their outlets were connected to a modified Gerlach through for sediments retention and, subsequently, a tipping-bucket device and a tank for recording and collecting the runoff. The overland flow generated by the plots was monitored for almost one year. In addition, soil moisture content was measured automatically at 0-2, 5-10 and 15-20cm soil depth using 5 sensors per plot. Furthermore, soil water repellency was repeatedly measured on the field, through ethanol percentage method. In the dense eucalyptus forest the soil is hydrophobic during most of the year, just vanished after severe rainfall events. This reflects on low soil moisture content that reached 37% during wet periods. In this area, with an average slope of 20°±5°, the runoff coefficient ranged between 0.0% (for a 3mm rainfall event) and 2.2% (for a 23mm rainfall during hydrophobic conditions). In general, the runoff was higher when the soil was extremely repellent, but it also increased with soil moisture rise when the repellence was absent (reaching 0.6%). In the open eucalyptus forest, hydrophobicity is also presented

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Long-term changes in precipitation and stream water chemistry in small forest and moorland catchments at Beddgelert Forest, north Wales

    NASA Astrophysics Data System (ADS)

    Reynolds, B.; Stevens, P. A.; Brittain, S. A.; Norris, D. A.; Hughes, S.; Woods, C.

    Changes in the chemistry of bulk precipitation and stream water between 1982 and 2000 are described for small moorland and forest catchments located within Beddgelert Forest in north Wales. Two forest catchments were partially clearfelled in 1984 (D2; 68% and D4; 28%) whilst a third (D3) remained as an unfelled control until autumn / winter 1998/99 when partial felling took place in the headwaters. Over the monitoring period, the annual mean pH of bulk precipitation increased from 4.6 to 5.1 whilst the annual mean non-seasalt sulphate concentration decreased from 0.53 mg S l-1 in 1985 to 0.24 mg S l-1 in 2000. Since 1985, the annual wet deposition flux of non-seasalt sulphur decreased by 50% to 8.4 kg S ha-1 yr-1 in 2000. Annual mean inorganic nitrogen concentrations and annual wet deposition fluxes have remained relatively unchanged since 1982. The decrease in atmospheric sulphur deposition is reflected by decreased annual mean concentrations of non-seasalt sulphur, acidity, aluminium and calcium in all four streams irrespective of clearfelling activities. Annual variations in nitrate-N and potassium concentrations in the forest streams, largely determined by pulses of leaching following forest clearance, had no effect on stream acidity. In common with UK upland catchments, annual mean concentrations of dissolved organic carbon have increased from about 1 mg C l-1 in 1985 to between 1.5 and 2 mg C l-1 in 2000, although there is considerable year to year variability. Two boreholes drilled adjacent to catchments D3 and D4 have confirmed the presence of alkaline, base rich groundwater at Beddgelert. Although the boreholes are only 150 m apart, there are large differences in chemistry suggesting that different groundwater reservoirs have been intercepted providing further evidence of the complexity and heterogeneity of groundwater systems in upland catchments.

  12. 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

  13. 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.

  14. 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

  15. Wildfire effects on water quality in forest catchments: A review with implications for water supply

    NASA Astrophysics Data System (ADS)

    Smith, Hugh G.; Sheridan, Gary J.; Lane, Patrick N. J.; Nyman, Petter; Haydon, Shane

    2011-01-01

    SummaryWildfires burn extensive forest areas around the world each year. In many locations, fire-prone forest catchments are utilised for the supply of potable water to small communities up to large cities. Following wildfire, increased erosion rates and changes to runoff generation and pollutant sources may greatly increase fluxes of sediment, nutrients and other water quality constituents, potentially contaminating water supplies. Most research to date has focused on suspended sediment exports and concentrations after wildfire. Reported first year post-fire suspended sediment exports varied from 0.017 to 50 t ha -1 year -1 across a large range of catchment sizes (0.021-1655 km 2). This represented an estimated increase of 1-1459 times unburned exports. Maximum reported concentrations of total suspended solids in streams for the first year after fire ranged from 11 to ˜500,000 mg L -1. Similarly, there was a large range in first year post-fire stream exports of total N (1.1-27 kg ha -1 year -1) and total P (0.03-3.2 kg ha -1 year -1), representing a multiple change of 0.3-431 times unburned, while NO3- exports of 0.04-13.0 kg ha -1 year -1 (3-250 times unburned) have been reported. NO3-, NO2-, and NH 3/ NH4+ concentrations in streams and lakes or reservoirs may increase after wildfire but appear to present a generally low risk of exceeding drinking water guidelines. Few studies have examined post-fire exports of trace elements. The limited observations of trace element concentrations in streams after wildfire found high levels (well over guidelines) of Fe, Mn, As, Cr, Al, Ba, and Pb, which were associated with highly elevated sediment concentrations. In contrast, Cu, Zn, and Hg were below or only slightly above guideline values. Elevated Na +, Cl - and SO42- solute yields have been recorded soon after fire, while reports of concentrations of these constituents were mostly confined to coniferous forest areas in North America, where maximum sampled values were well

  16. Bedload exports in a forest catchment following wildfire and terracing, north-central Portugal

    NASA Astrophysics Data System (ADS)

    Martins, Martinho A. S.; Machado, Ana I.; Serpa, Dalila; Prats, Sergio A.; Faria, Sílvia R.; Varela, María E. T.; González-Pelayo, Óscar; Keizer, J. Jacob

    2014-05-01

    In Portugal, the occurrences of wildfires are frequently, on average, affects some 100.000 ha of rural lands each year, but in extreme years such as 2003 and 2005 the burnt areas can go over 300.000 ha. Studies in various parts of the world, including Portugal, have well-documented a strong and sometimes extreme response in overland flow generation and associated soil losses following wildfire. Over the last two decades, the construction of terraces in preparation of a new eucalypt plantation has become increasingly common in the mountain areas of north-central Portugal, including in recently burnt areas. Terraces are traditionally viewed as a soil conservation technique, however, the present authors have measured high splash and inter-rill erosion on recent terraces and have frequently observed gully formation connecting the terraces over the full hill slope length, as well as within the adjacent unsealed roads. The present study was carried out in a forest catchment in the north-central Portugal that was burnt by a wildfire during the summer of 2010 and logged and then terraced with a bulldozer during the winter 2010. The burnt catchment of roughly 25 ha was instrumented with two subsequent flumes with maximum discharge capacities of 120 and 1700 l sec-1. The bed load that deposited in the smallest flume was removed and weighted in the field at regular intervals during the subsequent three years. The records are being now analyzed, nonetheless preliminary results suggested that, besides the wildfire effects, also post-fire land management played an important role on bedload exports.

  17. 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

  18. 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

  19. 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.

  20. Lithium isotope systematics in a forested granitic catchment (Strengbach, Vosges Mountains, France)

    NASA Astrophysics Data System (ADS)

    Lemarchand, Emmanuel; Chabaux, François; Vigier, Nathalie; Millot, Romain; Pierret, Marie-Claire

    2010-08-01

    Over the last decade it has become apparent that Li isotopes may be a good proxy to trace silicate weathering. However, the exact mechanisms which drive the behaviour of Li isotopes in surface environments are not totally understood and there is a need to better calibrate and characterize this proxy. In this study, we analysed the Li concentrations and isotopic compositions in the various surface reservoirs (soils, rocks, waters and plants) of a small forested granitic catchment located in the Vosges Mountains (Strengbach catchment, France, OHGE http://ohge.u-strasbg.fr). Li fluxes were calculated in both soil profiles and at the basin scale and it was found that even in this forested basin, atmospheric inputs and litter fall represented a minor flux compared to input derived from the weathering of rocks and soil minerals (which together represent a minimum of 70% of dissolved Li). Li isotope ratios in soil pore waters show large depth dependent variations. Average dissolved δ 7Li decreases from -1.1‰ to -14.4‰ between 0 and -30 cm, but is +30.7‰ at -60 cm. This range of Li isotopic compositions is very large and it encompasses almost the entire range of terrestrial Li isotope compositions that have been previously reported. We interpret these variations to result from both the dissolution and precipitation of secondary phases. Large isotopic variations were also measured in the springs and stream waters, with δ 7Li varying from +5.3‰ to +19.6‰. δ 7Li increases from the top to the bottom of the basin and also covaries with discharge at the outlet. These variations are interpreted to reflect isotopic fractionations occurring during secondary phase precipitation along the water pathway through the rocks. We suggest that the dissolved δ 7Li increases with increasing residence time of waters through the rocks, and so with increasing time of interaction between waters and solids. A dissolution precipitation model was used to fit the dissolved Li isotopic

  1. 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.

    2012-10-01

    Subtropical forests in South 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 hill slope (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 in 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 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 (0.50 and 0.41 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 South China are an important, hitherto overlooked component of the anthropogenic N2O budget.

  2. 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.

  3. 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

  4. Calcium losses from a forested catchment in south-central Ontario, Canada.

    PubMed

    Watmough, Shaun A; Dillon, Peter J

    2003-07-15

    Mass balance studies at a number of calibrated watersheds in eastern North America suggest that large losses of Ca from soil have occurred due to acid deposition. However, there is considerable controversy over whether losses have occurred from the exchangeable pool or whether there are other sources of Ca that have not been considered. Mass balance calculations at a small, calibrated catchment (PC1) in south-central Ontario also indicate that large losses of Ca have occurred over the past 2 decades. If the exchangeable Ca pool has declined by approximately 40% between 1983/1984 and 1998/1999 but the exchangeable Mg pool has remained relatively stable, these changes should be evident in streamwater chemistry. The slope of the buffer curve relating Ca to (sigma)acid anions (F(Ca)) decreased significantly over the study period. We estimate that F(Ca) decreased by 12-24% between 1983 and 1999, although the level of decrease is affected by changes in hydrology. During the same period, there was no significant change in F(Mg), and the annual volume-weighted Ca:Mg (equiv/equiv) ratio in streamwater decreased from approximately 2.8 to approximately 2.1. Measured changes in streamwater chemistry translate into Ca losses from the exchangeable pool of approximately 250-570 mequiv/m2 over the study period, which is similar to estimated losses based on soil measurements (approximately 425 mequiv/m2) and mass balance calculations (approximately 380-430 mequiv/m2). The magnitude of Ca loss cannot be explained by decreases in Ca deposition or decreased Ca weathering. Large Ca losses from the soil exchangeable pool have serious implications for future forest health and the recovery of streamwater from acid deposition.

  5. 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

  6. 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.

  7. 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.

  8. Composition and mean residence time of soil organic matter eroded from temperate, forested catchments: implications for erosion-induced carbon sequestration

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Topsoil and associated soil organic matter are continuously laterally distributed on the landscape by the process of soil erosion. The role of soil erosion on terrestrial carbon sequestration has been gaining a lot of attention over the last two decades. Soil erosion has been shown to lead to a sink of atmospheric carbon dioxide in soil if at least some of the eroded carbon is replaced by production of new photosynthate and/or some of the eroded carbon is stabilized in downslope depositional landform positions. However, until recently most of the work in this area has been focused on agricultural or grassland systems. Here, we present results from temperate forested catchments in the southern part of the Sierra Nevada Mountains. We found that most of the soil organic matter eroded from low-order catchments in the western slope of the Sierra Nevada Mountains is composed of forest floor material that has high concentrations of carbon. The steep slopes of these catchments also contribute to export of large proportion of the eroded forest floor material out of the catchments. Our radiocarbon analyses showed that the soil organic matter in the eroded material is composed of modern (post-1950) carbon with fraction modern values at or above 1. We also found that neither elevation, nor climate (across six years that we investigated) leads to significant changes in the composition and mean residence times of the eroded material, despite considerable differences in mean residence time of soil organic mater in soil profiles of the contributing hillslopes in the high vs. low elevation (low elevation: 1800 m, high elevation: 2300 m) catchments we studied. Our findings show that soil organic matter eroded from upland forested catchments is a lot more susceptible to decomposition, compared to organic matter eroded from agricultural or grassland systems likely leading to a less significant role of soil erosion on terrestrial carbon sequestration in forested catchments.

  9. Sediment and solute yield in forest ecosystems affected by fire and rip-ploughing techniques, central portugal: A plot and catchment analysis approach

    NASA Astrophysics Data System (ADS)

    Ferreira, A. J. D.; Coelho, C. O. A.; Shakesby, R. A.; Walsh, R. P. D.

    In the last two decades, Portuguese forests have undergone important changes in land use and management practices, some of which are posing significant problems as regards long-term sustainability of forestry. This paper examines the degradation processes associated with two events: deep ploughing prior to planting (termed ‘ripploughing’) and forest fire. The research design comprised plot and catchment approaches in which fluxes of water, sediment and solutes for rip-ploughed and burnt pine forest were monitored for the first year after ploughing and fire respectively. Although rip-ploughed areas experienced very high erosion rates at the plot scale (up to 51 t ha -1 yr -1) and enhanced catchment runoff due to increased overland flow (up to 50% of rainfall), catchment sediment yield was small because of sediment storage at the bases of slopes and in channel heads. For burned pine, the destruction of the vegetation and litter layer led to sharp increases in catchment runoff and nutrient losses both as dissolved and suspended sediments. Despite sediment loss at the plot scale being below 3 t ha -1 in the first year after the fire, the catchment suspended sediment loss in storm events was several orders of magnitude higher than for the partly rip-ploughed catchment.

  10. Vegetation correlates of gibbon density in the peat-swamp forest of the Sabangau catchment, Central Kalimantan, Indonesia.

    PubMed

    Hamard, Marie; Cheyne, Susan M; Nijman, Vincent

    2010-06-01

    Understanding the complex relationship between primates and their habitats is essential for effective conservation plans. Peat-swamp forest has recently been recognized as an important habitat for the Southern Bornean gibbon (Hylobates albibarbis), but information is scarce on the factors that link gibbon density to characteristics of this unique ecosystem. Our aims in this study were firstly to estimate gibbon density in different forest subtypes in a newly protected, secondary peat-swamp forest in the Sabangau Catchment, Indonesia, and secondly to identify which vegetation characteristics correlate with gibbon density. Data collection was conducted in a 37.1 km(2) area, using auditory sampling methods and vegetation "speed plotting". Gibbon densities varied between survey sites from 1.39 to 3.92 groups/km(2). Canopy cover, tree height, density of large trees and food availability were significantly correlated with gibbon density, identifying the preservation of tall trees and good canopy cover as a conservation priority for the gibbon population in the Sabangau forest. This survey indicates that selective logging, which specifically targets large trees and disrupts canopy cover, is likely to have adverse effects on gibbon populations in peat-swamp forests, and calls for greater protection of these little-studied ecosystems.

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

    PubMed

    Novák, Martin; Mitchell, Myron J; Jacková, Iva; Buzek, Frantisek; Schweigstillová, Jana; Erbanová, Lucie; Prikryl, Richard; Fottová, Daniela

    2007-02-01

    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 delta18O-SO4 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(-1) yr(-1), respectively). The second catchment, Na Lizu, was 10 times less polluted. In both catchments, delta18O-SO4 decreased in the following order: open-area precipitation > throughfall > runoff. The delta18O-SO4 values of throughfall exhibited a seasonal pattern at both sites, with maxima in summer and minima in winter. This seasonal pattern paralleled delta18O-H2O values, which were offset by -18 per thousand. Sulfate in throughfall was predominantly formed by heterogeneous (aqueous) oxidation of SO2. Wet-deposited sulfate in an open area did not show systematic delta18O-SO4 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 18O-rich sulfate was not detected, which contrasts with North American industrial sites.

  12. Catchment-scale distribution of radiocesium air dose rate in a mountainous deciduous forest and its relation to topography.

    PubMed

    Atarashi-Andoh, Mariko; Koarashi, Jun; Takeuchi, Erina; Tsuduki, Katsunori; Nishimura, Syusaku; Matsunaga, Takeshi

    2015-09-01

    A large number of air dose rate measurements were collected by walking through a mountainous area with a small gamma-ray survey system, KURAMA-II. The data were used to map the air dose rate of a mountainous deciduous forest that received radiocesium from the Fukushima Dai-ichi Nuclear Power Plant accident. Measurements were conducted in a small stream catchment (0.6 km(2) in area) in August and September 2013, and the relationship between air dose rates and the mountainous topography was examined. Air dose rates increased with elevation, indicating that more radiocesium was deposited on ridges, and suggesting that it had remained there for 2.5 y with no significant downslope migration by soil erosion or water drainage. Orientation in relation to the dominant winds when the radioactive plume flowed to the catchment also strongly affected the air dose rates. Based on our continuous measurements using the KURAMA-II, we describe the variation in air dose rates in a mountainous forest area and suggest that it is important to consider topography when determining sampling points and resolution to assess the spatial variability of dose rates and contaminant deposition.

  13. 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.

  14. 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

  15. 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

  16. 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

  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. 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...

  19. 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...

  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. 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.

  2. 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

  3. 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.

  4. 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

  5. Streamflow generation from snowmelt in semi-arid, seasonally snow-covered, forested catchments, Valles Caldera, New Mexico

    NASA Astrophysics Data System (ADS)

    Liu, Fengjing; Bales, Roger C.; Conklin, Martha H.; Conrad, Mark E.

    2008-12-01

    Streamflow generation in the semiarid, seasonally snow-covered, and forested mountain catchments of the Valles Caldera, New Mexico, was investigated using chemical tracers. Samples were collected from snow, subsurface flow from hillslopes, and streamflow at Redondo and La Jara Creeks from December 2004 to July 2005. A new modeling procedure was developed by combining diagnostic tools of mixing models and end-member mixing analysis to evaluate the assumptions of mixing models. This procedure was successfully used to determine conservative chemical tracers, identify the number of end-members that contribute to streamflow, and evaluate eligibility of end-members. The results show that streamflow at Redondo Creek was generated from two end-members: lateral subsurface flow (˜80%) and thermal meteoric water (˜20%). Streamflow at La Jara Creek was primarily from lateral subsurface flow alone. Overland flow of snowmelt was not a significant contributor to streamflow in either catchment. Lateral subsurface flow is an important process of streamflow generation in semiarid environments in the southwest United States and should play a critical role in regulating biogeochemical cycles.

  6. 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.

  7. 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.

  8. 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

  9. Operational validation of a multi-period and multi-criteria model conditioning approach for the prediction of rainfall-runoff processes in small forest catchments

    NASA Astrophysics Data System (ADS)

    Choi, H.; Kim, S.

    2012-12-01

    Most of hydrologic models have generally been used to describe and represent the spatio-temporal variability of hydrological processes in the watershed scale. Though it is an obvious fact that hydrological responses have the time varying nature, optimal values of model parameters were normally considered as time invariants or constants in most cases. The recent paper of Choi and Beven (2007) presents a multi-period and multi-criteria model conditioning approach. The approach is based on the equifinality thesis within the Generalised Likelihood Uncertainty Estimation (GLUE) framework. In their application, the behavioural TOPMODEL parameter sets are determined by several performance measures for global (annual) and short (30-days) periods, clustered using a Fuzzy C-means algorithm, into 15 types representing different hydrological conditions. Their study shows a good performance on the calibration of a rainfall-runoff model in a forest catchment, and also gives strong indications that it is uncommon to find model realizations that were behavioural over all multi-periods and all performance measures, and multi-period model conditioning approach may become new effective tool for predictions of hydrological processes in ungauged catchments. This study is a follow-up study on the Choi and Beven's (2007) model conditioning approach to test how the approach is effective for the prediction of rainfall-runoff responses in ungauged catchments. To achieve this purpose, 6 small forest catchments are selected among the several hydrological experimental catchments operated by Korea Forest Research Institute. In each catchment, long-term hydrological time series data varying from 10 to 30 years were available. The areas of the selected catchments range from 13.6 to 37.8 ha, and all areas are covered by coniferous or broad-leaves forests. The selected catchments locate in the southern coastal area to the northern part of South Korea. The bed rocks are Granite gneiss, Granite or

  10. 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

  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.

  12. 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.

  13. 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

  14. 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

  15. Looking Beyond the Old Water Paradox: Does New Water Dominate Quick Hydrographs where Surface Flowpaths Prevail? - A Meta-Analysis of Field Evidence from Small, Forested Catchments

    NASA Astrophysics Data System (ADS)

    Barthold, F. K.; Woods, R. A.

    2015-12-01

    The old water paradox describes the rapid mobilization of previously stored water via subsurface flowpaths during a storm event. Old water is usually stored in the subsurface storages. Thus, old water should dominate storm runoff where subsurface flowpaths prevail if mixing with new water is limited. The argumentum e contrario from this understanding raises the following hypothesis: storm hydrographs of catchments with prevailing near surface flowpaths are dominated by new water. We test this hypothesis using data from the scientific literature. The three runoff characteristics hydrograph response (quick or slow), flowpath (surface or subsurface) and time source (old or new water) serve as basis for a conceptual framework of catchment classification where each possible combination of the three characteristics represents a distinct stormflow generation conceptual model. Small forested research catchments for which conceptual models were developed based on field studies were reviewed and assigned to this classification system. Of the 42 reviewed catchments, 30 provide a complete set of the three characteristics resulting in one of the 8 conceptual models. Four catchments support our hypothesis, however, a larger field support exists for subsurface than for surface flowpath dominated sites. Hence, the resulting theory that hydrographs are dominated by new water where surface flowpaths prevail remains highly uncertain. Two explanations exist for the imbalance of field support between the two flowpath classes: 1) the selection of sites in past field studies was mainly to explain quick hydrograph response in subsurface flowpaths dominated catchments; 2) sites with prevailing subsurface flowpaths are more common in nature. We conclude that field studies at sites covering a broader range of characteristics are necessary to understand stormflow generation. The collection of catchments also allows us to test how the three runoff characteristics relate to climate, soils and

  16. 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...

  17. 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.

  18. Calibration of a lumped nitrogen model in a Mediterranean forested catchment named Fuirosos, (Catalonia).

    NASA Astrophysics Data System (ADS)

    Medici, C.; Butturini, A.; Bernal, S.; Sabater, F.; Martin, M.; Wade, A.; Frances, F.

    2009-04-01

    Following the philosophy of the process-based INCA-N model (Wade et al., 2004), a recently developed hydrological model, LU4 was extended through the inclusion of processes representing the inorganic nitrogen cycle to create a new model of nitrogen dynamics LU4-N capable of application in Mediterranean systems, which share processes from both wet and arid/semiarid environments (Gallart et al., 2002). This new model represents an advance on the INCA-N model for which problems where observed when simulating the hydrology of Mediterranean catchments (Bernal et al., 2004). The LU4-N model integrates hydrological and N processes in catchment and simulates daily discharge and daily NO3-N and NH4-N concentration. The lumped hydrological model LU4 has been already applied to the Fuirosos catchment giving acceptable results (Medici et al., 2008). The model provides a simplified conceptualization of nitrogen cycle in soil and into the shallow perched saturated zone. It uses a zero order reaction kinetic equation to simulate the mineralization process and first order equation to simulate non-biological fixation, nitrification, denitrification, plant uptake and immobilization. The model structure includes a soil moisture threshold for all the considered soil biological processes. The model also includes two first order reaction equations to simulate the adsorption/desorption dynamic in soil. In the shallow perched aquifer, nitrification and denitrification are the only processes allowed to occur. The calibration period for the N-submodel was the same considered for the calibration of the hydrological model LU4 and it covers approximately three hydrological years (from October 1999 to August 2002). The LU4-N model was also tested against observed data recorded at Fuirosos from August 2002 to June 2003. The LU4-N model was able to match the observed daily pattern for the calibration period, while it was unable to match satisfactorily the daily observed ammonium concentration

  19. 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...

  20. 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...

  1. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 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...

  2. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 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...

  3. 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...

  4. 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

  5. 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.

  6. Distributed modeling of storm flow generation in an Amazonian rain forest catchment: Effects of model parameterization

    NASA Astrophysics Data System (ADS)

    Vertessy, Robert A.; Elsenbeer, Helmut

    1999-07-01

    We describe a process-based storm flow generation model, Topog_SBM consisting of a simple bucket model for soil water accounting, a one-dimensional kinematic wave overland flow scheme, and a contour-based element network for routing surface and subsurface flows. Aside from topographic data and rainfall the model has only six input parameters: soil depth (z), saturated hydraulic conductivity at the soil surface (K0), the rate of decay in K0 with depth (m), the Manning surface roughness parameter (n), the maximum (saturated) soil water content (θs), and the minimum (residual) soil water content (θr). However, the model is fully distributed, so these values can vary in magnitude across space. The model was applied to La Cuenca, a very small rainforest catchment in western Amazonia that has been well characterized in several hydrometric and hydrochemical investigations. Total runoff, peak runoff, time of rise, and lag time were predicted for 34 events of varying magnitudes and antecedent moisture conditions. We compared results for eight different model parameterizations or "sets"; four of these were freely calibrated to yield the best possible model fit to runoff data, whereas the other four were constrained (in various ways) by the use of actual K0 data gathered for the catchment. The eight sets were calibrated on either one of three events or on the three events jointly to illustrate the importance of calibration event selection on model performance. Model performance was evaluated by comparing observed and predicted (1) storm flow hydrograph attributes and (2) spatiotemporal patterns of overland flow occurrence across the catchment. The model generally predicted the right amount of runoff but usually underpredicted the peak runoff rate and overpredicted the time of rise. The "best" parameterization could credibly predict hydrographs for only about half of the events. Significant, and sometimes gross, errors were encountered for about one fourth of the events

  7. Steam flow generation in semi-arid, forested and seasonally snow-covered catchments, Valles Caldera, New Mexico

    NASA Astrophysics Data System (ADS)

    Liu, F.; Bales, R. C.; Conklin, M. H.; Kostrzewski, J. M.

    2005-12-01

    Stream flow generation is poorly understood for semi-arid, forested and seasonally snow-covered catchments in southwest US. Here we report on initial results of a pioneer study on source waters and flowpaths using isotopic and geochemical tracers in two streams originated from Redondo Peak in Valles Caldera, New Mexico. The Valles Caldera is the latest collapse feature in the volcanic field and hosts high-temperature hydrothermal systems with several geothermal springs. It is currently covered by ponderosa pine in lower elevations and mixed conifer in higher elevations. Samples were collected from snow, hillslope groundwater, and stream water at Redondo Creek and La Jara Creek from December 2004 to July 2005. Using diagnostic tools of mixing models and end-member mixing analysis, it is suggested that stream water quantity and quality at Redondo Creek were primarily controlled by mixing of two end-members: hillslope subsurface water and geothermal springs. Hillslope subsurface water was sourced from snowmelt and then gradually released to stream flow through spring and summer. Infiltration-excess overland flow of snowmelt did not appear to occur. Contribution of hillslope subsurface water to stream flow was 90% on average from December 2004 to July 2005 and its percentage gradually increased from spring to summer with increase in discharge. Contribution of geothermal springs decreased on percentage over season with a peak (20%) in late march and lowest but relatively constant value (5%) through June and July. Stream flow generation at La Jara Creek was relatively simple, all from hillslope subsurface water. This information may improve our understanding of changes of hydrological and biogeochemical cycles in response to climate warming in these and similar catchments in southwest US.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. The impact of vegetation on REE fractionation in stream waters of a small forested catchment (the Strengbach case)

    NASA Astrophysics Data System (ADS)

    Stille, P.; Steinmann, M.; Pierret, M.-C.; Gauthier-Lafaye, F.; Chabaux, F.; Viville, D.; Pourcelot, L.; Matera, V.; Aouad, G.; Aubert, D.

    2006-07-01

    Previous studies on waters of a streamlet in the Vosges Mountains (Eastern France) have shown that strontium and rare earth elements (REE) mainly originate from preferential dissolution of apatite during weathering. However, stream water REE patterns normalized to apatite are still depleted in the light REE (LREE, La-Sm) pointing to the presence of an additional LREE depleting process. Vegetation samples are strongly enriched in LREE compared to stream water and their Sr and Nd isotopic compositions are comparable with those of apatite and stream water. Thus, the preferential LREE uptake by vegetation might lead to an additional LREE depletion of surface runoff in the forested catchment. Mass balance calculations indicate, that the yearly LREE uptake by vegetation is comparable with the LREE export by the streamlet and, therefore, might be an important factor controlling LREE depletion in river water. This is underlined by the observation that rivers from arctic and boreal regions with sparse vegetation appear to be less depleted in LREE than rivers from tropical environments or boreal environments with a dense vegetation cover.

  13. 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

  14. 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

  15. Infiltration and water storage in forest soils at the plot and the micro- catchment scale

    NASA Astrophysics Data System (ADS)

    Stimm, Eva-Maria; Lange, Benjamin; Lüscher, Peter; Germann, Peter; Weingartner, Rolf

    2010-05-01

    Tree roots generate and conserve hydrologically active macropores. We explored the influence of root density on infiltration and water storage at six 1-m2 plots along an 8-m transect between two mature trees (spruce). The soil is a Flysch-based stagnic Cambisol with a flow-impeding horizon at a depth of about 60 cm. At a plot the experimental set up consisted of a 1m x 1m sprinkler and five Decagon HS-10 soil-moisture probes that were horizontally mounted from a trench into the centre of each horizon. We irrigated each plot three times at 24-hour intervals during one hour with a rate of 70 mm h-1. Data logging was at 60-seconds intervals that produced time series of water contents due to irrigation and drainage. After irrigation, soil cores of 10 cm diameter were sampled. Roots were extracted from the cores and their densities were optically analysed with the program "whinRIZO". The application of a rivulet approach to the time series of water contents produced the thickness F (μm) and the specific contact length L (m m-2) per cross-sectional area of the water films that represent Stokes-flow. The procedure leads to estimates of storage capacity and hydraulic connectivity in the vertical and lateral directions along the transect. Extrapolation from the transect to the micro-catchment scale is based on maps showing the spatial arrangements of trees, shrubs and soil properties like thickness and hydrological parameters of horizons.

  16. 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.

  17. 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

  18. 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

  19. Dissolved organic sulfur in streams draining forested catchments in southern China.

    PubMed

    Wang, Zhanyi; Zhang, Xiaoshan; Wang, Zhangwei; Zhang, Yi; Li, Bingwen; Vogt, Rolf

    2012-01-01

    Dissolved organic sulfur (DOS) is an important fraction for sulfur mobilization in ecosystem. In this work stream waters were sampled in 25 forested sites in southern China to study the dissolved sulfur fractions. Dissolved sulfur was fractionated into dissolved organic sulfur (DOS) and inorganic sulfate (SO4(2-)) for 95 stream water samples. The results showed that the concentration of DOS ranged from 0 to 13.1 mg/L (average 1.3 mg/L) in all the streams. High concentrations of DOS in stream waters were found in the sites with high concentrations of sulfate. DOS constituted less than 60.1% of dissolved sulfur (average 17.9%). Statistical analysis showed that DOS concentration was correlated with SO4(2-) in streams waters and total sulfur in surface layer soils. The results also showed that DOS concentration in stream waters had a seasonal variation, but no trends were found with it. The implication was that the long term sulfur deposition had led the increase of the concentration and fraction of DOS in stream waters in acid rain prevailing regions

  20. Dissolved organic sulfur in streams draining forested catchments in southern China.

    PubMed

    Wang, Zhanyi; Zhang, Xiaoshan; Wang, Zhangwei; Zhang, Yi; Li, Bingwen; Vogt, Rolf

    2012-01-01

    Dissolved organic sulfur (DOS) is an important fraction for sulfur mobilization in ecosystem. In this work stream waters were sampled in 25 forested sites in southern China to study the dissolved sulfur fractions. Dissolved sulfur was fractionated into dissolved organic sulfur (DOS) and inorganic sulfate (SO4(2-)) for 95 stream water samples. The results showed that the concentration of DOS ranged from 0 to 13.1 mg/L (average 1.3 mg/L) in all the streams. High concentrations of DOS in stream waters were found in the sites with high concentrations of sulfate. DOS constituted less than 60.1% of dissolved sulfur (average 17.9%). Statistical analysis showed that DOS concentration was correlated with SO4(2-) in streams waters and total sulfur in surface layer soils. The results also showed that DOS concentration in stream waters had a seasonal variation, but no trends were found with it. The implication was that the long term sulfur deposition had led the increase of the concentration and fraction of DOS in stream waters in acid rain prevailing regions PMID:22894106

  1. 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.

  2. 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.

  3. Increasing arsenic concentrations in runoff from 12 small forested catchments (Czech Republic, Central Europe): patterns and controls.

    PubMed

    Novak, Martin; Erbanova, Lucie; Fottova, Daniela; Voldrichova, Petra; Prechova, Eva; Blaha, Vladimir; Veselovsky, Frantisek; Krachler, Michael

    2010-08-01

    The 40-year long period of heavy industrialization in Central Europe (1950-1990) was accompanied by burning of arsenic-rich lignite in thermal power plants, and accumulation of anthropogenic arsenic in forest soils. There are fears that retreating acidification may lead to arsenic mobilization into drinking water, caused by competitive ligand exchange. We present monthly arsenic concentrations in surface runoff from 12 headwater catchments in the Czech Republic for a period of 13 years (1996-2008). The studied area was characterized by a north-south gradient of decreasing pollution. Acidification, caused mainly by SOx and NOx emissions from power plants, has been retreating since 1987. Between 1996 and 2003, maximum arsenic concentrations in runoff did not change, and were < 1 ppb in the rural south and < 2 ppb in the industrial north. During the subsequent two years, 2004-2005, maximum arsenic concentrations in runoff increased, reaching 60% of the drinking water limit (10 ppb). Starting in 2006, maximum arsenic concentrations returned to lower values at most sites. We discuss three possible causes of the recent arsenic concentration maximum in runoff. We rule out retreating acidification and a pulse of high industrial emission rates as possible controls. The pH of runoff has not changed since 1996, and is still too low (<6.5) at most sites for an As-OH(-) ligand exchange to become significant. Elevated arsenic concentrations in runoff in 2004-2005 may reflect climate change through changing hydrological conditions at some, but not all sites. Dry conditions may result in elevated production of DOC and sulfur oxidation in the soil. Subsequent wet conditions may be accompanied by acidification leading to faster dissolution of arsenic-bearing sulfides, dissolution of arsenic-bearing Fe-oxyhydroxides, and elevated transport of arsenic sorbed on organic matter. Anaerobic domains exist in normally well-aerated upland soils for hours-to-days following precipitation

  4. Throughflow and solute transport in an isolated sloping soil block in a forested catchment

    NASA Astrophysics Data System (ADS)

    Hornberger, George M.; Germann, Peter F.; Beven, Keith J.

    1991-04-01

    A 3m wide by 9m long by 1m deep soil block on a forested hillslope near Orono, ME, was isolated by excavation of encircling trenches. A sprinkler system for application of water and potassium bromide tracer was constructed over the plot. Outflow was collected at six locations with troughs. Experiments were conducted at application rates of 2.5, 5, and 10 cm h -1. Pulses of tracer were applied subsequent to attainment of steady flow and breakthrough curves were measured at all outflow points. Recession limbs of outflow hydrographs exhibited distinct breaks when plotted on semilogarithmic axes, indicating drainage from at least two distinguishable pore size classes or flow pathways. Solute breakthrough curves were dominated by a single peak; travel times of solute were inversely related to the application rate. A secondary peak in the outflow curve, which is inconsistent with transport theories for a homogeneous soil, was observed in all cases. This second peak is unexplained, but is conceptually consistent with the notion of transport in at least two pore size classes. An undisturbed soil core (diameter of 30 cm and length of 40 cm) was sprinkled at the same rates as was the soil block, using Methylene Blue as tracer in the last run. Drainage hydrographs and visual examination of dye stains in the block indicated also at this smaller scale that flow and transport are controlled by preferred paths in the soil, paths that cannot be morphologically distinguished from the surrounding soil matrix. Theoretical explanations of processes on such hillslopes need to account for this fact.

  5. Atmospheric deposition, mineralization and leaching of nitrogen in subtropical forested catchments, South China.

    PubMed

    Chen, X Y; Mulder, J; Wang, Y H; Zhao, D W; Xiang, R J

    2004-01-01

    In recent years, China has conducted considerable research focusing on the emission and effects of sulphur (S) on human health and ecosystems. By contrast, there has been little emphasis on anthropogenic nitrogen (N) so far, even though studies conducted abroad indicate that long-range atmospheric transport of N and ecological effects (e.g. acidification of soil and water) may be significant. The Sino-Norwegian project IMPACTS, launched in 1999, has established monitoring sites at five forest ecosystems in the southern part of PR China to collect comprehensive data on air quality, acidification status and ecological effects. Here we present initial results about N dynamics at two of the IMPACTS sites located near Chongqing and Changsha, including estimation of atmospheric deposition fluxes of NOx and NHx and soil N transformations. Nitrogen deposition is high at both sites when compared with values from Europe and North America (25-38 kg ha(-1) yr(-1)). About 70% of the deposited N comes as NH4, probably derived from agriculture. Leaching of N from soils is high and nearly all as NO3-. Transformation of N to NO3- in soils results in acidification rates that are high compared to rates found elsewhere. Despite considerable leaching of NO3- from the root zone of the soils, little NO3- appears in streamwater. This indicates that N retention or denitrification, both causing acid neutralization, may be important and probably occur in the groundwater and groundwater discharge zones. The soil flux density of mineral N, which is the sum of N deposition and N mineralization, and which is dominated by the N mineralization flux, may be a good indicator for leaching of NO3- in soils. However, this indicator seems site specific probably due to differences in land-use history and current N requirement.

  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. 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

  9. 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... With an Emergency Permit § 108.25 Acidified foods. (a) Inadequate or improper manufacture,...

  10. 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... With an Emergency Permit § 108.25 Acidified foods. (a) Inadequate or improper manufacture,...

  11. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 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 HUMAN... With an Emergency Permit § 108.25 Acidified foods. (a) Inadequate or improper manufacture,...

  12. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 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 HUMAN... With an Emergency Permit § 108.25 Acidified foods. (a) Inadequate or improper manufacture,...

  13. [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.

  14. [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

  15. 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

  16. The impact of water-rock interaction and vegetation on calcium isotope fractionation in soil- and stream waters of a small, forested catchment (the Strengbach case)

    NASA Astrophysics Data System (ADS)

    Cenki-Tok, B.; Chabaux, F.; Lemarchand, D.; Schmitt, A.-D.; Pierret, M.-C.; Viville, D.; Bagard, M.-L.; Stille, P.

    2009-04-01

    This study aims to constrain the factors controlling the calcium isotopic compositions in surface waters, especially the respective role of vegetation and water-rock interactions on Ca isotope fractionation in a continental forested ecosystem. The approach is to follow changes in space and time of the isotopic composition and concentration of Ca along its pathway through the hydro-geochemical reservoirs from atmospheric deposits to the outlet of the watershed via throughfalls, percolating soil solutions and springs. The study is focused on the Strengbach catchment, a small forested watershed located in the northeast of France in the Vosges mountains. The δ 44/40Ca values of springs, brooks and stream waters from the catchment are comparable to those of continental rivers and fluctuate between 0.17 and 0.87‰. Soil solutions, however, are significantly depleted in lighter isotopes (δ 44/40Ca: 1.00-1.47‰), whereas vegetation is strongly enriched (δ 44/40Ca: -0.48‰ to +0.19‰). These results highlight that vegetation is a major factor controlling the calcium isotopic composition of soil solutions, with depletion in "light" calcium in the soil solutions from deeper parts of the soil compartments due to preferential 40Ca uptake by the plants rootsystem. However, mass balance calculations require the contribution of an additional Ca flux into the soil solutions most probably associated with water-rock interactions. The stream waters are marked by a seasonal variation of their δ 44/40Ca, with low δ 44/40Ca in winter and high δ 44/40Ca in spring, summer and autumn. For some springs, nourishing the streamlet, a decrease of the δ 44/40Ca value is observed when the discharge of the spring increases, with, in addition, a clear covariation between the δ 44/40Ca and corresponding H 4SiO 4 concentrations: high δ 44/40Ca values and low H 4SiO 4 concentrations at high discharge; low δ 44/40Ca values and high H 4SiO 4 concentrations at low discharge. These data imply

  17. 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

  18. Simulation of daily discharges for the upper Durance catchment (French Alps) using subgrid parameterization for topography and a forest canopy climate model

    NASA Astrophysics Data System (ADS)

    Strasser, Ulrich; Etchevers, Pierre

    2005-08-01

    This study describes the application of the coupled SAFRAN (meteorological variables), ISBA (soil-vegetation-atmosphere transfer) and CROCUS (snow cover evolution) models to simulate daily discharges for the upper Durance catchment (French Alps) from 1981 to 1994. The results are validated by comparison with measurements at three gauging stations located in the watershed. Previous investigations have shown a remarkable overestimation of the spring flood peak generated by the modelled snowmelt. It could be significantly improved by increasing the model resolution from 8 km to 1 km, thus more precisely considering the elevation-dependent snowmelt process. However, it is also possible to use subgrid parameterizations at the coarse grid resolution to improve simulations. This paper investigates the influence of a subgrid parameterization for topography, a subgrid parameterization for the snow cover in a forest canopy and a combination of the two on the simulated spring flood peak. Results show a significant improvement in the simulations by both subgrid parameterizations, in particular by their combination: the Nash-Sutcliffe efficiency of the daily discharges is improved from 0.73 (original experiment) to 0.77 (subgrid topography), to 0.75 (forest) and to 0.78 (combination of subgrid topography and forest).

  19. Seasonal and event variations in δ34S values of stream sulfate in a Vermont forested catchment: Implications for sulfur sources and cycling

    USGS Publications Warehouse

    Shanley, James B.; Mayer, Bernhard; Mitchell, Myron J.; Bailey, Scott W.

    2008-01-01

    Stable sulfur (S) isotope ratios can be used to identify the sources of sulfate contributing to streamwater. We collected weekly and high-flow stream samples for S isotopic analysis of sulfate through the entire water year 2003 plus the snowmelt period of 2004. The study area was the 41-ha forested W-9 catchment at Sleepers River Research Watershed, Vermont, a site known to produce sulfate from weathering of sulfide minerals in the bedrock. The δ34S values of streamwater sulfate followed an annual sinusoidal pattern ranging from about 6.5‰ in early spring to about 10‰ in early fall. During high-flow events, δ34S values typically decreased by 1 to 3‰ from the prevailing seasonal value. The isotopic evidence suggests that stream sulfate concentrations are controlled by: (1) an overall dominance of bedrock-derived sulfate (δ34S ~ 6–14‰); (2) contributions of pedogenic sulfate (δ34S ~ 5–6‰) during snowmelt and storms with progressively diminishing contributions during base flow recession; and (3) minor effects of dissimilatory bacterial sulfate reduction and subsequent reoxidation of sulfides. Bedrock should not be overlooked as a source of S in catchment sulfate budgets.

  20. 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

  1. 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.

  2. Long-term changes in aluminum fractions of drainage waters in two forest catchments with contrasting lithology.

    PubMed

    Krám, Pavel; Hruska, Jakub; Driscoll, Charles T; Johnson, Chris E; Oulehle, Filip

    2009-11-01

    Aluminum (Al) chemistry was studied in soils and waters of two catchments covered by spruce (Picea abies) monocultures in the Czech Republic that represent geochemical end-members of terrestrial and aquatic sensitivity to acidic deposition. The acid-sensitive Lysina catchment, underlain by granite, was compared to the acid-resistant Pluhův Bor catchment on serpentine. Organically-bound Al was the largest pool of reactive soil Al at both sites. Very high median total Al (Alt) concentrations (40 micromol L(-1)) and inorganic monomeric Al (Ali) concentrations (27 micromol L(-1)) were observed in acidic (pH 4.0) stream water at Lysina in the 1990s and these concentrations decreased to 32 micromol L(-1) (Alt) and 13 micromol L(-1) (Ali) in the 2000s. The potentially toxic Ali fraction decreased in response to long-term decreases in acidic deposition, but Ali remained the largest fraction. However, the organic monomeric (Alo) and particulate (Alp) fractions increased in the 2000s at Lysina. In contrast to Lysina, marked increases of Alt concentrations in circum-neutral waters at Pluhův Bor were observed in the 2000s in comparison with the 1990s. These increases were entirely due to the Alp fraction, which increased more than 3-fold in stream water and up to 8-fold in soil water in the A horizon. Increase of Alp coincided with dissolved organic carbon (DOC) increases. Acidification recovery may have increased the content of colloidal Al though the coagulation of monomeric Al.

  3. Calculating critical loads for acidification for five forested catchments in China using an extended steady state function.

    PubMed

    Zhao, Yu; Duan, Lei; Larssen, Thorjorn; Mulder, Jan; Hu, Lanhua; Hao, Jiming

    2007-11-15

    The critical load concept has become widely accepted as an important theoretical basis for establishing effective acid deposition control strategies. In the critical load calculations, the influence of variation in base cation (BC) deposition, which plays an important role in mitigating acidification, was seldom considered. In this manner, high uncertainty and over-estimation might be caused in those areas where current BC deposition is very high and of significant anthropogenic origin since anthropogenic deposition can change due to human activity. In this study, an extended sulfur(S)-nitrogen (N)-BC function based on the Steady State Mass Balance (SSMB) method is applied to calculate the critical loads for five sampled catchments in southern China under variable S, N, and BC deposition. The ceiling of S deposition (when N deposition is zero; CL(max)(S)) under current BC deposition varies from 4.5 to 10.8 keq ha(-1) yr(-1) among the five catchments, and the ceiling of N deposition (when S deposition is zero; CL(max)(N)) varies from 23.2 to 54.5 keq ha(-1) yr(-1). A 75% reduction in BC deposition is estimated to cause a 46%-86% decrease of CL(max)(S) and 45%-81% decrease of CL(max)(N). The critical loads for acidification are not exceeded in any of the five catchments under the current base cation deposition, despite extremely high S deposition in some places. However, if the BC deposition decreases to 25% of current while S remains unchanged, critical loads will be exceeded at all sites except one. A sensitivity analysis confirms that the long-term future BC deposition is among the most important parameters to the uncertainty of critical load, together with the dose-response relationship between ecosystem health and soil solution chemistry.

  4. Forest Harvesting of a Rocky Mountain Headwater Catchment: Assessing the Impacts on Runoff and Sediment Transport Into and Through Riparian Buffers

    NASA Astrophysics Data System (ADS)

    Puntenney, K.; Bladon, K. D.; Silins, U.

    2015-12-01

    Mitigating forest harvesting impacts by retaining a vegetated riparian buffer along headwater streams is a widely implemented best management practice. However, there is still debate over current retention practices and their effectiveness at regulating runoff, erosion, and sediment transport from harvested areas to streams. Forested, headwater catchments on the eastern slopes of the Rocky Mountains (49°37' N, 114°40' W) were harvested in winter 2015. Fixed-width (30 m) riparian buffers were retained based on the regional operating ground rules for all of the identified and mapped hydrologic features. Modified Gerlach troughs (total n=40) were installed along the cutblock-buffer interface, 10 m into the vegetated buffer, and in unharvested control sites to collect runoff and sediment. Site characteristics, including surface soil moisture, slope, vegetation cover, soil type, litter depth, and upslope accumulated area will be used to describe differences in runoff volumes and sediment concentrations between sites. Rainfall simulations are also being used to quantify and compare the initiation of runoff, runoff volumes, and sediment concentrations under high intensity precipitation events in cutblocks, at the cutblock-buffer interface, and within vegetated buffers. Broad objectives of this ongoing study are to identify spatio-temporal hotspots of runoff and sediment transport from cutblocks into and through riparian buffers.

  5. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., or packing of acidified foods may result in the distribution in interstate commerce of processed... list of foods so processed in each establishment. These forms are available from the LACF Registration... processing. (h) This section shall not apply to the commercial processing of any food processed under...

  6. 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)).

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  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. 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...

  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. 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

  17. 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.

  18. Ecohydrology of Lodgepole Pine Forests: Connecting Transpiration to Subsurface Flow Paths and Storage within a Subalpine Catchment

    NASA Astrophysics Data System (ADS)

    Byers, A.; Harpold, A. A.; Barnard, H. R.

    2011-12-01

    The hydrologic cycle plays a central role in regulating ecosystem structure and function. Linked studies of both subsurface and aboveground processes are needed to improve understanding of ecosystem changes that could result from climate change and disturbance in Colorado's subalpine forests. Here, we present data from plots dominated by lodgepole pine (Pinus contorta) at the Niwot Ridge LTER site on the Colorado Front Range that improves the process-level understanding of the source and fate of water between subsurface storage and plant uptake. This study utilized event-based sampling during the 2011 growing season to investigate a paradox between water sources and rooting depth in lodgepole pine. Findings from Niwot Ridge have shown that lodgepole, typically believed to be a shallow-rooted species, appear to be strongly dependent on water from snowmelt for the entire growing season. These results suggested that conifer species were accessing water from deeper in the soil than summer monsoon rain typically penetrated. In our study, the relationship between precipitation event size and depth of infiltration on a seasonal and event basis, the effective rooting depth of lodgepole pine, and hysteretic responses of transpiration to soil moisture over a growing season were examined using measurements of tree physiological processes (sap flux and water stress) and hydrological parameters (precipitation, soil moisture) as well as stable water isotope composition of xylem water, mobile and immobile soil water, snow, precipitation, and stream water. Analysis of data shows that soil moisture in deep layers (60 and 70 cm) responds to large summer rain events of 0.7 mm and greater, and that lodgepole sap flux increases by 15-30% within 24 hours of monsoon events and decreases over 72 hours or until subsequent rain. Water isotope analysis will further elucidate the source and event response of these trees. This research helps us understand whether processes known to occur in

  19. 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.

  20. 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.

  1. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...,” section 16.023. (d) Nomenclature. The name of the food is “Acidified sour cream”. The full name of the... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Acidified sour cream. 131.162 Section 131.162 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  2. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...,” section 16.023. (d) Nomenclature. The name of the food is “Acidified sour cream”. The full name of the... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Acidified sour cream. 131.162 Section 131.162 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  3. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...,” section 16.023. (d) Nomenclature. The name of the food is “Acidified sour cream”. The full name of the... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Acidified sour cream. 131.162 Section 131.162 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  4. Evaluation of dry deposition of acidifying N compounds to vegetation.

    PubMed

    Kumar, Ranjit; Kumari, K Maharaj

    2015-12-01

    This papers deals with direct measurements of dry deposition flux of total acidifying N species (gaseous HNO3 and particulate NO3(-)) and theoretically by parameterization method to vegetation (leaf surfaces) over a semiarid region in India. Annual average experimental dry deposition of NO3(-) to leaf of Cassia is 0.65 ± 0.61 mg m(-2) day(-1). Ambient concentrations of HNO3 vapor and particulate NO3(-) are 1.53 and 1.24 μg m(-3), respectively. Theoretically obtained dry deposition velocity of HNO3 and NO3(-) are 0.74 cm s(-1) for both while calculated dry deposition flux of total NO3(-) is found to be 1.3 ± 0.33 mg m(-2) day(-1). The measured dry deposition flux of NO3(-) to Cassia leaf is in the range of theoretically obtained flux. The annual input of N as nitrate is 3.8 mmol m(-2) year(-1) which is lower than the other forest site in China which is probably because of low pollution than China.

  5. The global distribution of acidifying wet deposition.

    PubMed

    Rodhe, Henning; Dentener, Frank; Schulz, Michael

    2002-10-15

    The acid-base status of precipitation is a result of a balance between acidifying compounds--mainly oxides of sulfur and nitrogen--and alkaline compounds--mainly ammonia and alkaline material in windblown soil dust. We use current models of the global atmospheric distribution of such compounds to estimate the geographical distribution of pH in precipitation and of the rate of deposition of hydrogen ion or bicarbonate ion. The lowest pH values--mainly due to high concentration of sulfuric acid--occur in eastern parts of North America, Europe, and China. A comparison with observed pH values shows fair agreement in most parts of the world. However, in some areas, e.g. western North America, southwestern Europe, and northern China the estimated pH is too low, indicating that we have underestimated the deposition flux of alkaline material, probably mainly CaCO3. Our neglect of organic acids may have contributed to an overestimate of pH especially in certain tropical areas. To illustrate the potential effects of acidifying deposition on nitrogen saturated terrestrial ecosystems we also calculate the deposition of "potential acidity" that takes into account the microbial transformation of ammonium to nitrate in such ecosystems, resulting in the release of hydrogen ion. Compared to the deposition of acidity, with its maxima over Europe, eastern North America, and southern China, the deposition of potential acidity exhibits an additional maximum in India and Bangladesh and in several other smaller hot spots where the cycling of ammonia is enhanced by a dense cattle population. To the extent that soils in these areas of high potential acidity deposition actually become nitrogen saturated a depletion of base cations and other changes in soil chemistry and biology should be expected. Potential problem areas forfuture soil acidification include several regions with sensitive soils in southern, southeastern, and eastern Asia as well as in central parts of South America.

  6. Long-term changes in the water quality of rainfall, cloud water and stream water for moorland, forested and clear-felled catchments at Plynlimon, mid-Wales

    NASA Astrophysics Data System (ADS)

    Neal, C.; Reynolds, B.; Neal, M.; Pugh, B.; Hill, L.; Wickham, H.

    Long term changes in the water quality of rainfall, cloud water and stream waters draining acidic and acid sensitive moorland and forested catchments at Plynlimon, mid-Wales, are examined for the period 1983 to 2001. Atmospheric inputs of chloride and sulphate are influenced by the relative inputs of clean maritime and polluted land based air masses. There is no systematic increase or decrease over time for chloride and non-sea-salt sulphate. Rather, there is a decadal scale process possibly representative of the influence of the North Atlantic Oscillation that affects the maritime and pollution climate of the Atlantic seaboard of the UK. Over 17 years of study, there may be a small decrease in non-sea-salt sulphate of about 10 μeq l-1 and a small improvement in acid neutralising capacity of about 20 to 30 μeq l-1 in rainfall. There is a clear improvement in cloud water chemistry with respect to pollutant components (ammonium, nitrate, non-sea-salt sulphate) and acidity (acid neutralising capacity improved by about 300 μeq l-1) through the study period. Many of the changes in cloud water chemistry are similar to rainfall over the same period except the magnitude of change is larger for the cloud water. Within the streams, there is some evidence for reductions in acidity as reflected by acid neutralising capacity becoming less negative. For one stream, deforestation occurred during the sampling period and this led to large increases in nitrate and smaller increases in aluminium midway through the study period. However, the climate and hydrological variability largely masked out other changes. The current analysis provides only a start to identifying trends for such a complex and variable environmental system. The need for strong statistical tools is emphasised to resolve issues of: (a) hydrological induced water quality variability, (b) changing soil and groundwater "endmember" chemistry contribution to the stream and (c) the non-linear patterns of change

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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.

  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. 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.

  14. Decrease of aflatoxin B1 in yoghurt and acidified milks.

    PubMed

    Rasić, J L; Skrinjar, M; Markov, S

    1991-02-01

    Fermentation of yoghurt and acidified milks containing aflatoxin B1 (AB1) were studied. AB1 added to milk before fermentation at concentrations of 600, 1000 and 1400 micrograms/kg was reduced in yoghurts (pH 4.0) by 97, 91 and 90%, respectively. Coagulation time was approximately the same as in the controls. Streptococci had longer chains than those in the controls. The main decrease of AB1 occurred during the milk fermentation. A decrease of AB1 (conc. 1000 micrograms/kg) in milks acidified with citric, lactic and acetic acids (pH 4.0) was 90, 84 and 73%, respectively.

  15. Trace metal biogeochemistry in mangrove ecosystems: a comparative assessment of acidified (by acid sulfate soils) and non-acidified sites.

    PubMed

    Nath, Bibhash; Birch, Gavin; Chaudhuri, Punarbasu

    2013-10-01

    The generation of acidity and subsequent mobilization of toxic metals induced by acid sulfate soils (ASSs) are known to cause severe environmental damage to many coastal wetlands and estuaries of Australia and worldwide. Mangrove ecosystems serve to protect coastal environments, but are increasingly threatened from such ASS-induced acidification due to variable hydrological conditions (i.e., inundation-desiccation cycles). However, the impact of such behaviors on trace metal distribution, bio-availability and accumulation in mangrove tissues, i.e., leaves and pneumatophores, are largely unknown. In this study, we examined how ASS-induced acidifications controlled trace metal distribution and bio-availability in gray mangrove (Avicennia marina) soils and in tissues in the Kooragang wetland, New South Wales, Australia. We collected mangrove soils, leaves and pneumatophores from a part of the wetland acidified from ASS (i.e., an affected site) for detailed biogeochemical studies. The results were compared with samples collected from a natural intertidal mangrove forest (i.e., a control site) located within the same wetland. Soil pH (mean: 5.90) indicated acidic conditions in the affected site, whereas pH was near-neutral (mean: 7.17) in the control site. The results did not show statistically significant differences in near-total and bio-available metal concentrations, except for Fe and Mn, between affected and control sites. Iron concentrations were significantly (p values≤0.001) greater in the affected site, whereas Mn concentrations were significantly (p values≤0.001) greater in the control site. However, large proportions of near-total metals were potentially bio-available in control sites. Concentrations of Fe and Ni were significantly (p values≤0.001) greater in leaves and pneumatophores of the affected sites, whereas Mn, Cu, Pb and Zn were greater in control sites. The degree of metal bio-accumulation in leaves and pneumatophores suggest contrasting

  16. Trace metal biogeochemistry in mangrove ecosystems: a comparative assessment of acidified (by acid sulfate soils) and non-acidified sites.

    PubMed

    Nath, Bibhash; Birch, Gavin; Chaudhuri, Punarbasu

    2013-10-01

    The generation of acidity and subsequent mobilization of toxic metals induced by acid sulfate soils (ASSs) are known to cause severe environmental damage to many coastal wetlands and estuaries of Australia and worldwide. Mangrove ecosystems serve to protect coastal environments, but are increasingly threatened from such ASS-induced acidification due to variable hydrological conditions (i.e., inundation-desiccation cycles). However, the impact of such behaviors on trace metal distribution, bio-availability and accumulation in mangrove tissues, i.e., leaves and pneumatophores, are largely unknown. In this study, we examined how ASS-induced acidifications controlled trace metal distribution and bio-availability in gray mangrove (Avicennia marina) soils and in tissues in the Kooragang wetland, New South Wales, Australia. We collected mangrove soils, leaves and pneumatophores from a part of the wetland acidified from ASS (i.e., an affected site) for detailed biogeochemical studies. The results were compared with samples collected from a natural intertidal mangrove forest (i.e., a control site) located within the same wetland. Soil pH (mean: 5.90) indicated acidic conditions in the affected site, whereas pH was near-neutral (mean: 7.17) in the control site. The results did not show statistically significant differences in near-total and bio-available metal concentrations, except for Fe and Mn, between affected and control sites. Iron concentrations were significantly (p values≤0.001) greater in the affected site, whereas Mn concentrations were significantly (p values≤0.001) greater in the control site. However, large proportions of near-total metals were potentially bio-available in control sites. Concentrations of Fe and Ni were significantly (p values≤0.001) greater in leaves and pneumatophores of the affected sites, whereas Mn, Cu, Pb and Zn were greater in control sites. The degree of metal bio-accumulation in leaves and pneumatophores suggest contrasting

  17. 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.

  18. 75 FR 59268 - Draft Guidance for Industry: Acidified Foods; Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-27

    .... 0910-0037; 73 FR 11649 at 11650, March 4, 2008). In that analysis, we estimated that there are 8,950... HUMAN SERVICES Food and Drug Administration Draft Guidance for Industry: Acidified Foods; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice. SUMMARY: The Food and Drug Administration...

  19. Modelling future soil chemistry at a highly polluted forest site at Istebna in Southern Poland using the "SAFE" model.

    PubMed

    Małek, Stanisław; Martinson, Liisa; Sverdrup, Harald

    2005-10-01

    The multi-layer dynamic model SAFE was applied to the forested catchment Istebna (Southern Poland), to study recovery from acidification. Environmental pollution in the area has been historically high. The model uses data from an intensive monitoring plot established in 1999 in a spruce stand, which was planted in 1880. Observations showed that the soil was depleted of base cations. The measured base saturation in 1999 was between 5 and 8% in the different soil layers. Model predictions assuming full implementation of the UNECE 1999 Gothenburg Protocol and present day base cation deposition show that the base saturation will slowly increase to 20% by 2100. Despite large emission reductions, Istebna still suffers from the very high loads of acidifying input during the past decades. Soil recovery depends on future emissions especially on base cation deposition. The recovery will be even slower if the base cation deposition decreases further.

  20. Catchment characterisation through Streamflow Component mixing Approach

    NASA Astrophysics Data System (ADS)

    Rusjan, Simon

    2013-04-01

    A simple dynamical system approach was implemented in order to analyse, explain and simulate streamflow fluxes in diverse seasonal hydrological conditions. The study was implemented within 42 km2 forested Padež stream catchment in SW part of Slovenia, which is characterized by flushing, almost torrential hydrological response conditioned by flysch geological settings of low hydraulic conductivity. The hydrological characteristics of the studied catchment at first sight do not comply with the hydrological catchment storage framework in which original concept of the catchment as a simple dynamical system was developed. In the studied catchment, the streamflow formation is not controlled solely by subsurface catchment storage but is strongly influenced also by rainfall runoff that bypasses the subsurface catchment storage mechanism. Therefore, two components of the streamflow were identified, described by separate sensitivity functions and combined through simple two component mixing model which enabled us simulation of the streamflow in highly contrasting seasonal hydrological settings. According to the simulation results, the Padež stream catchment behaves primarily like a storage-dependent system under conditions of low antecedent catchment wetness and low to moderate rainfall intensities (up to 5 mm/h) when subsurface storage sensitivity function generally managed to simulate streamflows with exception of hydrograph peak formation. When rainfall intensities increase (exceed approximately 5 mm/h), secondary streamflow formation mechanism described by subsurface storage bypassing sensitivity function becomes initiated and causes fast hydrograph formation with steeply rising and falling limbs. In order to be able to implement the modelling concept for streamflow predictions, the rainfall losses in growth period, most probably associated with interception losses not covered under the potential evapotranspiration calculation, would have to be more thoroughly analysed

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. Integrating soil water measurements from plot to catchment scale in a snow-dominated, mixed-conifer forest of the southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    vegetation. Three possible causes for the lack of moisture change are: 1) too few trees were removed; 2) canopy vegetation left on the forest floor had approximately equal water content as tree-stem wood removed; 3) tree-root water storage remained relatively unchanged. This research is part of the NSF-supported Southern Sierra Critical Zone Observatory, which is co-located within the U.S. Forest Service, Kings River Experimental Watershed.

  8. Effects of broadleaf woodland cover on streamwater chemistry and risk assessments of streamwater acidification in acid-sensitive catchments in the UK.

    PubMed

    Gagkas, Z; Heal, K V; Stuart, N; Nisbet, T R

    2008-07-01

    Streamwater was sampled at high flows from 14 catchments with different (0-78%) percentages of broadleaf woodland cover in acid-sensitive areas in the UK to investigate whether woodland cover affects streamwater acidification. Significant positive correlations were found between broadleaf woodland cover and streamwater NO3 and Al concentrations. Streamwater NO3 concentrations exceeded non-marine SO4 in three catchments with broadleaf woodland cover>or=50% indicating that NO3 was the principal excess acidifying ion in the catchments dominated by woodland. Comparison of calculated streamwater critical loads with acid deposition totals showed that 11 of the study catchments were not subject to acidification by acidic deposition. Critical loads were exceeded in three catchments, two of which were due to high NO3 concentrations in drainage from areas with large proportions of broadleaved woodland. The results suggest that the current risk assessment methodology should protect acid-sensitive catchments from potential acidification associated with broadleaf woodland expansion.

  9. 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

  10. Assessment of catchment scale connectivity in different catchments using measured suspended sediment output

    NASA Astrophysics Data System (ADS)

    Masselink, Rens; Keesstra, Saskia; Seeger, Manuel

    2014-05-01

    Recent developments in hydrology and geomorphology include the connectivity principle, which describes how different elements in a landscape are connected and how water and matter moves between these elements. So far, studies on connectivity have been mainly of a conceptual nature and have been done on a small scale, while studies that map, quantitatively establish relations, and model water and sediment transport in connectivity are rare. In this study we established a relation between change in connectivity within four catchments and the time of year by using suspended sediment data. The data were collected for four catchments in Navarra, Spain of which two catchments are dominated by forest and pasture, while the other two catchments are dominated by agriculture and have no forest. Data were collected during a 13 year period; 4 samples were taken a day at 6 hour intervals which were mixed to obtain a daily average suspended sediment concentration. This was then converted into daily suspended sediment output using the measured total daily discharge. The effect of precipitation on the sediment output data was minimized by using an antecedent precipitation index (API), which consists of the precipitation of the current day added by the precipitation of the previous 14 days, where the influence of the previous days decays exponentially with time. The daily total suspended sediment output was divided by the API, to obtain a measure for sediment output independent of precipitation. This sediment output then serves as a measure for the connectivity within the catchment. The connectivity of the four catchments throughout the years will be compared to each other and we hypothesise that the two catchments dominated by forests and pastures will change only slightly throughout the year, whereas we expect to see large differences in connectivity in the two agricultural catchments. The agricultural catchments are likely to display a highly varying connectivity throughout the

  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. 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.

  13. Boron water quality for the Plynlimon catchments

    NASA Astrophysics Data System (ADS)

    Neal, C.

    Boron concentrations in rainfall, throughfall and stemflow for Spruce stands, mist, streamwater and groundwater are compared with chloride to assess atmospheric sources and catchment input-output balances for the Plynlimon catchments. In rainfall, boron concentration averages about 4.5 μg-B l-1 and approximately two thirds of this comes from anthropogenic sources. In through-fall and stemflow, boron concentrations are approximately a factor of ten times higher than in rainfall. This increase is associated with enhanced scavenging of mist and dry deposition by the trees. As the sampling sites were close to a forest edge, this degree of scavenging is probably far higher than in the centre of the forest. The throughfall and stemflow concentrations of boron show some evidence of periodic variations with time with peak concentrations occurring during the summer months indicating some vegetational cycling. In mist, boron concentrations are almost twenty times higher than in rainfall and anthropogenic sources account for about 86% of this. Within the Plynlimon streams, boron concentrations are about 1.4 to 1.7 times higher than in rainfall. However, after allowance for mist and dry deposition contributions to atmospheric deposition, it seems that, on average, about 30% of the boron input is retained within the catchment. For the forested catchments, felling results in a disruption of the biological cycle and a small increase in boron leaching from the catchment results in the net retention by the catchment being slightly reduced. Despite the net uptake by the catchment, there is clear evidence of a boron component of weathering from the bedrock. This is shown by an increased boron concentration in a stream influenced by a nearby borehole which increased groundwater inputs. The weathering component for boron is also observed in Plynlimon groundwaters as boron concentrations and boron to chloride ratios are higher than for the streams. For these Goundwaters, increases in

  14. 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.

  15. 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).

  16. 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

  17. 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...

  18. Coral host cells acidify symbiotic algal microenvironment to promote photosynthesis

    PubMed Central

    Barott, Katie L.; Venn, Alexander A.; Perez, Sidney O.; Tambutté, Sylvie; Tresguerres, Martin

    2015-01-01

    Symbiotic dinoflagellate algae residing inside coral tissues supply the host with the majority of their energy requirements through the translocation of photosynthetically fixed carbon. The algae, in turn, rely on the host for the supply of inorganic carbon. Carbon must be concentrated as CO2 in order for photosynthesis to proceed, and here we show that the coral host plays an active role in this process. The host-derived symbiosome membrane surrounding the algae abundantly expresses vacuolar H+-ATPase (VHA), which acidifies the symbiosome space down to pH ∼4. Inhibition of VHA results in a significant decrease in average H+ activity in the symbiosome of up to 75% and a significant reduction in O2 production rate, a measure of photosynthetic activity. These results suggest that host VHA is part of a previously unidentified carbon concentrating mechanism for algal photosynthesis and provide mechanistic evidence that coral host cells can actively modulate the physiology of their symbionts. PMID:25548188

  19. 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

  20. 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

  1. 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.

  2. Comparison of forest edge effects on throughfall deposition in different forest types.

    PubMed

    Wuyts, Karen; De Schrijver, An; Staelens, Jeroen; Gielis, Leen; Vandenbruwane, Jeroen; Verheyen, Kris

    2008-12-01

    This study examined the influence of distance to the forest edge, forest type, and time on Cl-, SO4(2-), NO3(-), and NH4+ throughfall deposition in forest edges. The forests were dominated by pedunculate oak, silver birch, or Corsican/Austrian pine, and were situated in two regions of Flanders (Belgium). Along transects, throughfall deposition was monitored at distances of 0-128 m from the forest edge. A repeated-measures analysis demonstrated that time, forest type, and distance to the forest edge significantly influenced throughfall deposition of the ions studied. The effect of distance to the forest edge depended significantly on forest type in the deposition of Cl-, SO4(2-), and NO3(-): the edge effect was significantly greater in pine stands than in deciduous birch and oak stands. This finding supports the possibility of converting pine plantations into oak or birch forests in order to mitigate the input of nitrogen and potentially acidifying deposition.

  3. Process performance of anaerobic co-digestion of raw and acidified pig slurry.

    PubMed

    Moset, V; Cerisuelo, A; Sutaryo, S; Møller, H B

    2012-10-15

    The effect of incorporating different ratios of acidified pig slurry on methane yield was evaluated in two scales of anaerobic digesters: Thermophilic (50 °C) pilot scale digester (120 l), operating with an average hydraulic retention time of 20 days and thermophilic (52 °C) full-scale digesters (10 and 30 m(3)), operating with an average hydraulic retention time of 30 days. In the lab-scale digester, different inclusion levels of acidified slurry (0-60%) were tested each 15 days, to determine the maximum ratio of acidified to non-acidified slurry causing inhibition and to find process state indicators helping to prevent process failure. In the full-scale digesters, the level of inclusion of the acidified slurry was chosen from the ratio causing methane inhibition in the pilot scale experiment and was carried on in a long-term process of 100 days. The optimal inclusion level of acidified pig slurry in anaerobic co-digestion with conventional slurry was 10%, which promoted anaerobic methane yield by nearly 20%. Higher inclusion levels caused methane inhibition and volatile fatty acids accumulations in both experiments. In order to prevent process failure, the most important traits to monitor in the anaerobic digestion of acidified pig slurry were found to be: sulfate content of the slurry, alkalinity parameters (especially partial alkalinity and the ratio of alkalinity) and total volatile fatty acids (especially acetic and butyric acids).

  4. 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

  5. The impact of catchment conifer plantation forestry on the hydrochemistry of peatland lakes.

    PubMed

    Drinan, T J; Graham, C T; O'Halloran, J; Harrison, S S C

    2013-01-15

    The hydrochemistry of 26 small blanket bog lakes was examined to assess the impact of conifer plantation forestry on lake water chemistry. Lakes were selected from three distinct catchment land use categories: i) unplanted blanket bog only present in the catchment, ii) mature (closed-canopy) conifer plantation forests only present in the catchment and iii) catchments containing mature conifer plantation forests with recently clearfelled areas. All three catchment land uses were replicated across two geologies: sedimentary (sandstone) and igneous (granite). Lakes with afforested catchments across both geologies had elevated concentrations of phosphorus (P), nitrogen (N), total dissolved organic carbon (TDOC), aluminium (Al) and iron (Fe), with the highest concentrations of each parameter recorded from lakes with catchment clearfelling. Dissolved oxygen was also significantly reduced in the afforested lakes, particularly the clearfell lakes. Analysis of runoff from a nearby recently clearfelled site revealed high biological and chemical oxygen demands, consistent with at least part of the elevated concentrations of TDOC emanating from clearfelled sites having higher biochemical lability. Inorganic fertilisers applied at the start of the forest cycle, the decay of the underlying peat soil and accumulated surface tree litter, and leachate from felled trees are the likely sources of the elevated concentrations of plant nutrients, TDOC, heavy metals and major ions, with excessive peat soil disturbance during clearfelling likely exacerbating the runoff into lakes. Our study has demonstrated a clear, deleterious impact of conifer plantations on the water quality draining from blanket bog catchments, with major implications for the management of afforested peatlands.

  6. Antimicrobial activity and stability of weakly acidified chlorous acid water.

    PubMed

    Horiuchi, Isanori; Kawata, Hiroyuki; Nagao, Tamiko; Imaohji, Haruyuki; Murakami, Kazuya; Kino, Yasuhiro; Yamasaki, Hisashi; Koyama, A Hajime; Fujita, Yatsuka; Goda, Hisataka; Kuwahara, Tomomi

    2015-01-01

    The antimicrobial activity of weakly acidified chlorous acid water (WACAW) against Staphylococcus aureus, non-pathogenic Escherichia coli, enterohemorrhagic E. coli (EHEC O157:H7), Candida albicans, and spore-forming Bacillus and Paenibacillus species was evaluated in vitro. The antiviral activity was also examined using feline calicivirus (FCV). Diluted WACAW (>100 ppm) effectively reduced the number of non-spore-forming bacteria (>4 log10 CFU reductions) within 5 min. Treatment with this sanitizer at 400 ppm for 30 min achieved>5 log10 CFU reductions in spore-forming Bacillus and Paenibacillus species while an equivalent concentration of sodium hypochlorite (NaClO) resulted in only a 0.98 and 2.72 log10 CFU reduction, respectively. The effect of this sanitizer against FCV was equivalent to that of NaClO. Immersion in WACAW (400 ppm) achieved >4 and 2.26 log10 CFU reductions in Campylobacter jejuni and EHEC, respectively, on artificially contaminated broiler carcass pieces. Finally, theantimicrobial activity of this sanitizer was shown to be maintained for at least 28 d when in contact with nonwoven fabric (100% cotton). This study showed that pH control of chlorous acid is expected to modify its antimicrobial activity and stability. WACAW is expected to have applications in various settings such as the food processing and healthcare industries. PMID:25817812

  7. High resolution mapping of total deposition of acidifying pollutants

    NASA Astrophysics Data System (ADS)

    de Vos, Thierri; Zhang, Leiming

    2012-09-01

    A framework has been developed to estimate dry and wet deposition over Southern Belgium for a variety of acidifying substances on a 5 × 5 km2 grid. Concentrations of different compounds in the atmosphere or in the precipitation are provided by the measurement networks (both stations and gauges) and are interpolated over Southern Belgium. Dry deposition velocities are calculated using local meteorology and land use information, following the approach described in Zhang et al. (2001, 2003). Local precipitation is provided by merged radar-gauge observations. This is the first high resolution framework for Southern Belgium computing both time- and space-dependent deposition, using a modified kriging interpolation method (for SO2 and NO2), as well as radar-based precipitation. Estimated dry and wet depositions are compared with long range transport (LRT) model results, based on the European emission inventories. Although a good agreement is observed between our results and LRT model results on the annual totals averaged over Southern Belgium, the extent of agreement for the spatial variability of the annual deposition differs significantly from one pollutant to another. This new framework provides consistent high resolution maps for several pollutants, while improving the mapping of dry and wet deposition in Southern Belgium, in order to assess critical loads exceedances.

  8. Acidifying and yeast extract in diets for adults cats.

    PubMed

    Ogoshi, Rosana C S; Zangeronimo, Márcio G; Dos Reis, Jéssica S; França, Janine; Santos, João P F; Pires, Carolina P; Chizzotti, Ana F; Costa, Adriano C; Ferreira, Lívia G; Saad, Flávia M O B

    2014-05-01

    This study evaluated the effects of adding an acidifying agent based on phosphoric acid (A), a yeast extract from a specific strain (Saccharomyces cerevisiae) (Y) and the combination of these two additives in food for adult cats. A test was conducted with 24 animals (mean 3.5 years old), mixed breed, weighing 3.72 ± 0.74 kg, kept in individual metabolic cages and distributed in a completely randomized design with a 2 × 2 factorial design (with or without A 0.6% of dry matter, with or without Y 1.5% of dry matter) totalling four treatments and six replicates of each condition. The experimental period was 15 days. The A or the Y reduced (P< 0.01) the dry matter intake, but the effect was not observed when they were associated. The association improved (P<0.05) the digestibility of dry matter and ashes. The A reduced urine pH (P=0.05) regardless of the presence of the Y. There was no effect (P>0.09) on other parameters evaluated. Results of this study show that the isolated use of 0.6% A or 1.5% Y in diets for cats is not recommended. However, the association of these two additives was beneficial in increasing nutrient digestibility.

  9. Predicting long-term recovery of a strongly acidified stream using MAGIC and climate models (Litavka, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Hardekopf, D. W.; Horecký, J.; Kopáček, J.; Stuchlík, E.

    2008-03-01

    Two branches forming the headwaters of a stream in the Czech Republic were studied. Both streams have similar catchment characteristics and historical deposition; however one is rain-fed and strongly affected by acid atmospheric deposition, the other spring-fed and only moderately acidified. The MAGIC model was used to reconstruct past stream water and soil chemistry of the rain-fed branch, and predict future recovery up to 2050 under current proposed emissions levels. A future increase in air temperature calculated by a regional climate model was then used to derive climate-related scenarios to test possible factors affecting chemical recovery up to 2100. Macroinvertebrates were sampled from both branches, and differences in stream chemistry were reflected in the community structures. According to modelled forecasts, recovery of the rain-fed branch will be gradual and limited, and continued high levels of sulphate release from the soils will continue to dominate stream water chemistry, while scenarios related to a predicted increase in temperature will have little impact. The likelihood of colonization of species from the spring-fed branch was evaluated considering the predicted extent of chemical recovery. The results suggest that the possibility of colonization of species from the spring-fed branch to the rain-fed will be limited to only the acid-tolerant stonefly, caddisfly and dipteran taxa in the modelled period.

  10. Predicting long-term recovery of a strongly acidified stream using MAGIC and climate models (Litavka, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Hardekopf, D. W.; Horecký, J.; Kopáček, J.; Stuchlík, E.

    2007-09-01

    Two branches forming the headwaters of a stream in the Czech Republic were studied. Both streams have similar catchment characteristics and historical deposition; however one is rain-fed and strongly affected by acid atmospheric deposition, the other spring-fed and only moderately acidified. The MAGIC model was used to reconstruct past stream water and soil chemistry of the rain-fed branch, and predict future recovery up to 2050 under current proposed emissions levels. A future increase in air temperature calculated by a regional climate model was then used to derive climate-related scenarios to test possible factors affecting chemical recovery up to 2100. Macroinvertebrates were sampled from both branches, and differences in stream chemistry were reflected in the community structures. According to modelled forecasts, recovery of the rain-fed branch will be gradual and limited, and continued high levels of sulphate release from the soils will continue to dominate stream water chemistry, while scenarios related to a predicted increase temperature will have little impact. The likelihood of colonization of species from the spring-fed branch was evaluated considering the predicted extent of chemical recovery. The results suggest that the possibility of colonization of species from the spring-fed branch to the rain-fed will be limited to only the acid-tolerant stonefly, caddisfly and dipteran taxa in the modelled period.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. Soil weathering rates in 21 catchments of the Canadian Shield

    NASA Astrophysics Data System (ADS)

    Houle, D.; Lamoureux, P.; Bélanger, N.; Bouchard, M.; Gagnon, C.; Couture, S.; Bouffard, A.

    2012-03-01

    Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K) for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha-1 yr-1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64) with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51%. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas as well as adequately predict absolute weathering rates values

  16. 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

  17. 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.

  18. 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

  19. 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

  20. Flood generation and sediment transport in experimental catchments affected by land use changes in the central Pyrenees

    NASA Astrophysics Data System (ADS)

    García-Ruiz, José M.; Regüés, David; Alvera, Bernardo; Lana-Renault, Noemí; Serrano-Muela, Pilar; Nadal-Romero, Estela; Navas, Ana; Latron, Jérôme; Martí-Bono, Carlos; Arnáez, José

    2008-07-01

    SummaryThree small catchments (<2.5 km2 in size) were monitored in the Central Spanish Pyrenees to analyse the hydrological and geomorphological consequences of different land covers under the same climate scenario: (i) the San Salvador catchment represents a dense, undisturbed forest environment; (ii) the Arnás catchment corresponds to an old, abandoned cultivated area subjected to colonisation by plants; and (iii) the Araguás catchment consists in part of active badlands. The obtained results demonstrate that plant cover is a key factor, influencing (i) the seasonality and intensity of floods, (ii) the annual volume of discharge, and (iii) the suspended sediment concentration, total sediment yield and proportions of different types of sediment. The forested catchment tends to generate floods in late winter and spring, when the water table is close to the surface, and flood hydrographs are generally gentle, with solutes largely prevailing over suspended sediment. The old agricultural catchment produces in average twice the number of floods as that recorded in the forested catchment, with the highest floods recorded in autumn and spring; this catchment behaves as a complex mosaic, with a large spatial and temporal variability in terms of both sediment- and runoff-contributing areas; in addition, suspended sediment is equal to solutes, and bedload reaches a relatively high importance. Finally, the badland catchment reacts to all rainstorm events throughout the year, with a high suspended-sediment load. Sediment outputs from the Araguás catchment are two orders of magnitude higher than in the Arnás and San Salvador catchments. Suspended sediment concentrations exceed 300 g l-1 in the Araguás catchment, whereas they rarely exceed 20 g l-1 in the Arnás and rarely 1.5 g l-1 in the San Salvador catchment.

  1. Recovery from acidification in the Tillingbourne catchment, southern England: catchment description and preliminary results.

    PubMed

    Hill, T J; Skeffington, R A; Whitehead, P G

    2002-01-23

    Measurements of acid deposition and streamwater chemistry made in 1979-1982 and 1999-2000 are compared for a small, acid-sensitive catchment in Southeast England. The location, geology, soils, vegetation and hydrology of the catchment are described. The catchment is located on an acidic cretaceous sandstone with a low permeability clay sub-stratum. Soils are predominantly podzol and gley, with some mesotrophic peat. The catchment is forested. Mean volume-weighted concentrations in precipitation have changed approximately in proportion to emission changes. SO4(2-) has declined by 61%, H+ by 75%, both NO- and NH4+ by 37% and Cl- by 26%. Changes in wet deposition are greater, sulfate deposition declined by 69%, non-marine SO4(2-) by 73%, H+ deposition by 75%, NO3- and NH4+ by 50% and Cl- by 41%. Sulfate deposition in throughfall, a surrogate for total deposition measurement, has declined by 82% and non-marine SO4(2-) by 86%. Some of these changes are due to alterations in the tree cover and location of the collectors. In 1979-1982, the flux of NO3- and NH4+ in throughfall was less than in rainfall, 7.5 compared with 11.3 kg N ha(-1) year(-1), showing that N uptake by the canopy was greater than dry deposition of these species. However, in 1999-2000, the throughfall flux of N was greater than rainfall, 19.6 compared to 5.7 kg N ha year(-1), indicating that canopy uptake is not occurring to the same extent. Surface water was sampled at the same locations in the catchment during the two periods. At the catchment exit, mean pH increased, from 3.93 to 4.21 mg l(-1), and SO4(2-) declined from 20.2 to 16.7 mg l(-1) (18%). The decrease in SO4(2-) is much less than the reduction in deposition, suggesting that the predicted recovery is being delayed by release of sulfur from the soil. In contrast, NO3- concentrations in the catchment waters increased from 0.22 to 0.52 mg N l(-1) (133%) despite the reduction in N deposition. NH4+ concentrations were low during both study periods

  2. 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.

  3. A methodological comparison of catchment storages in mountainous catchments

    NASA Astrophysics Data System (ADS)

    Weiler, Markus; Staudinger, Maria; Stölzle, Michael; Seeger, Stefan; Seibert, Jan; Stahl, Kerstin

    2015-04-01

    One of the most important functions of catchments is the temporary storage of water, which directly influences runoff dynamics, rainfall-runoff transformation, partitioning of evaporation and runoff fluxes, and accessibility of water to plants. Generally, a large catchment storage is considered beneficial and in particular increases the transit times and hence the buffer functioning related to water quality. Many different methods have been developed to assess catchment storage, however, there are hardly any direct comparisons of several of these methods. One challenge is the definition of water storage, while some methods allow estimation of the entire water storage in a catchment, other methods quantify only the dynamic storage. In addition, most studies focused more on lowland catchments with rain-dominated runoff regimes and observed groundwater fluctuations. Furthermore, these studies often focus on one or two catchments, but do not consider the influence of different climates on the relevance of water storage in the catchment. We applied a range of different methods to assess catchment storage characteristics in 18 catchments in the Swiss Alps, ranging from 500 to 2000m of mean elevation and hence from rainfall- to snowmelt dominated runoff regimes. The first method use only discharge information during recession periods and with varying approaches to extract discharge and storage changes between high flow and low flow, the dynamic catchment storage can be derived. In the next methods the conceptual hydrological model HBV is calibrated to the runoff dynamics and the dynamic and total catchment storages of the different compartments are being evaluated. The last methods are based on stable water isotope data analysis. We use the model TRANSEP to derive the dynamic storage as well as the total water storage of the catchment based on the transit times using several years of fortnightly isotope data in streamflow. The results show that the derived catchment

  4. Catchment controls on solute export

    NASA Astrophysics Data System (ADS)

    Musolff, Andreas; Schmidt, Christian; Selle, Benny; Fleckenstein, Jan H.

    2015-12-01

    Dynamics of solute export from catchments can be classified in terms of chemostatic and chemodynamic export regimes by an analysis of concentration-discharge relationships. Previous studies hypothesized that distinct export regimes emerge from the presence of solute mass stores within the catchment and their connectivity to the stream. However, so far a direct link of solute export to identifiable catchment characteristics is missing. Here we investigate long-term time series of stream water quality and quantity of nine neighboring catchments in Central Germany ranging from relatively pristine mountain catchments to agriculturally dominated lowland catchments, spanning large gradients in land use, geology, and climatic conditions. Given the strong collinearity of catchment characteristics we used partial least square regression analysis to quantify the predictive power of these characteristics for median concentrations and the metrics of export regime. We can show that median concentrations and metrics of the export regimes of major ions and nutrients can indeed be inferred from catchment characteristics. Strongest predictors for median concentrations were the share of arable land, discharge per area, runoff coefficient and available water capacity in the root zone of the catchments. The available water capacity in the root zone, the share of arable land being artificially drained and the topographic gradient were found to be the most relevant predictors for the metrics of export regime. These catchment characteristics can represent the size of solute mass store such as the fraction of arable land being a measure for the store of nitrate. On the other hand, catchment characteristics can be a measure for the connectivity of these solute stores to the stream such as the fraction of tile drained land in the catchments. This study demonstrates the potential of data-driven, top down analyses using simple metrics to classify and better understand dominant controls of

  5. Accumulation of different sulfur fractions in Chinese forest soil under acid deposition.

    PubMed

    Wang, Zhanyi; Zhang, Xiaoshan; Zhang, Yi; Wang, Zhangwei; Mulder, Jan

    2011-09-01

    Atmogenic sulfur (S) deposition loading by acid rain is one of the biggest environmental problems in China. It is important to know the accumulated S stored in soil, because eventually the size (and also the "desorption" rate) determines how rapidly the soil water pH responds to decrease in S deposition. The S fractions and the ratio of total carbon/total sulfur (C/S) of forest soil in 9 catchments were investigated by comparing soils at the rural and urban sites in China. The S fractions included water-soluble sulfate-S (SO(4)-S), adsorbed SO(4)-S, insoluble SO(4)-S and organic S. The ratio of C/S in soil at the rural site was significantly (p < 0.05) greater than that at the urban site. C/S of soil in the A horizon was significantly (p < 0.05) and negatively correlated with the wet S-deposition rate. The ratio of C/S presents a better indicator for atmogenic S loading. Organic S was the dominant form in soils at rural sites; contributing more than 69% of the total S in the uppermost 30 cm soil. Organic S and adsorbed SO(4)-S were the main forms of S in soil at urban sites. High contents of water-soluble SO(4)-S and adsorbed SO(4)-S were found in uppermost 30 cm soils at urban sites but not at rural sites. Decades of acid rain have caused accumulation of inorganic SO(4)-S in Chinese forest soil especially at the urban sites. The soil at urban sites had been firstly acidified, and the impacts on the forest ecosystem in these areas should be noticed.

  6. 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.

  7. Detecting non-stationary hydrologic model parameters in a paired catchment system using data assimilation

    NASA Astrophysics Data System (ADS)

    Pathiraja, S.; Marshall, L.; Sharma, A.; Moradkhani, H.

    2016-08-01

    Non-stationarity represents one of the major challenges facing hydrologists. There exists a need to develop modelling systems that are capable of accounting for potential catchment changes, in order to provide useful predictions for the future. Such changes may be due to climatic temporal variations or human induced changes to land cover. Extensive research has been undertaken on the impacts of land-use change on hydrologic behaviour, however, few studies have examined this issue in a predictive modelling context. In this paper, we investigate whether a time varying model parameter estimation framework that uses the principles of Data Assimilation can improve prediction for two pairs of experimental catchments in Western Australia. All catchments were initially forested, but after three years one catchment was fully cleared whilst another had only 50% of its area cleared. Their adjacent catchments remained unchanged as a control. Temporal variations in parameters were detected for both treated catchments, with no comparable variations for the control catchments. Improved streamflow prediction and representation of soil moisture dynamics were also seen for the time varying parameter case, compared to when a time invariant parameter set from the calibration period was used. While we use the above mentioned catchments to illustrate the usefulness of the approach, the methods are generic and equally applicable in other settings. This study serves as an important validation step to demonstrate the potential for time varying model structures to improve both predictions and modelling of changing catchments.

  8. Carbon redistribution by erosion processes in an intensively disturbed catchment

    NASA Astrophysics Data System (ADS)

    Boix-Fayos, Carolina; Martínez-Mena, María; Pérez Cutillas, Pedro; de Vente, Joris; Barberá, Gonzalo G.; Mosch, Wouter; Navarro Cano, Jose Antonio; Gaspar, Leticia; Navas, Ana

    2016-04-01

    Understanding how organic carbon moves with sediments along the fluvial system is crucial to close catchment scale carbon budgets. Especially challenging is the analysis of organic carbon dynamics during fluvial transport in heterogeneous, fragile and disturbed environments with ephemeral and intense hydrological pulses, typical of Mediterranean conditions. This paper explores the catchment scale organic carbon redistribution by lateral flows in extreme Mediterranean environmental conditions from a geomorphological perspective. The study area is a catchment (Cárcavo) in SE Spain with a semiarid climate, erodible lithologies, shallow soils, and highly disturbed by agricultural terraces, land levelling, reforestations and construction of check-dams. To increase understanding of erosion induced catchment scale organic carbon redistribution, we studied the subcatchments of 8 check-dams distributed along the catchment main channel in detail. We determined 137Cs, physicochemical characteristics and organic carbon pools of soils and sediments deposited behind each check-dam, performed spatial analysis of properties of the catchment and buffer areas around check-dams, and carried out geomorphological analysis of the slope-channel connections. Soils showed very low Total Organic Carbon (TOC) values oscillating between 15.2 and 4.4 g Kg-1 for forest and agricultural soils, respectively. Sediments mobilized by erosion were poor in TOC compared to the eroded (forest) soils (6.6±0.7 g Kg-1), and the redistribution of organic carbon through the catchment, especially of the Mineral Associated Organic Carbon (MAC) pool, showed the same pattern as clay particles and 137Cs. The TOC erosion rates (0.031±0.03 Mg ha-1 y-1) were comparable to others reported for subhumid Mediterranean catchments and to those modelled worldwide for pasture land. Those lateral fluxes were equivalent to 10.4 % of the TOC stock from the topsoil at the moment of the check-dam construction and

  9. Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments

    NASA Astrophysics Data System (ADS)

    Reader, H. E.; Stedmon, C. A.; Kritzberg, E. S.

    2014-06-01

    To examine the potential influence of terrestrially derived DOM on the Baltic Sea, a year-long study of dissolved organic matter (DOM) was performed in three river catchments in Sweden. One catchment drains into the Bothnian Sea, while two southern catchments drain into the Baltic proper. Dissolved organic carbon (DOC) concentrations were positively correlated with discharge from forested catchments over the year. While the overall concentrations of DOC were several times higher in the southern two catchments, higher discharge in the northern catchment resulted in the annual loadings of DOC being on the same order of magnitude for all three catchments. Biological oxygen demand (BOD) was used as a proxy for the lability of carbon in the system. The range of BOD values was similar for all three catchments, however, the ratio of BOD to DOC (an indication of the labile fraction) in Ume river was four times higher than in the southern two catchments. Total annual BOD loading to the Baltic Sea was twice as high in the northern catchment than in the two southern catchments. Lower winter temperatures and preservation of organic matter in the northern catchment combined with an intense spring flood help to explain the higher concentrations of labile carbon in the northern catchment. Lower lability of DOM as well as higher colour in the southern catchments suggest that wetlands (i.e. peat bogs) may be the dominant source of DOM in these catchments, particularly in periods of low flow. With climate change expected to increase precipitation events and temperatures across the region, the supply and quality of DOM delivered to the Baltic Sea can also be expected to change. Our results indicate that DOM supply to the Baltic Sea from boreal rivers will be more stable throughout the year, and potentially have a lower bioavailability.

  10. The "Teflon basin" myth: Snow-soil interactions in mountain catchments in the western US

    NASA Astrophysics Data System (ADS)

    Williams, M. W.; Cowie, R. M.

    2015-12-01

    In much of western North America, snow and snowmelt provide the primary means for storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. A common assumption is that high-elevation catchments in the western United States behave like "Teflon basins" and that water released from seasonal storage in snow packs flows directly into streams with little or no interaction with underlying soils. Here I present information from a variety of catchments in the Colorado Front Range on snowmelt/soil interactions using isotopic, geochemical, nutrient and hydrometric data in 2- and 3- component hydrograph separations, along with end-member mixing analysis (EMMA). For most catchments we measured these parameters in weekly precipitation, the seasonal snowpack, snowmelt before contact with the ground, discharge, springs, soil solution, and groundwater. We ran EMMA at the catchment scale for catchments that represent the rain-snow transition zone in the montane forest, the seasonally snow covered sub-alpine to alpine transition zone, and a high-elevation alpine zone near the continental divide. In all catchments three end-members were the source waters for about 95% of discharge. Two end-members were the same in all catchments, snow and groundwater. For the alpine catchment talus springs was the third water source, while rain was the third water source in the two lower-elevation catchments. For all three catchments, soil solution plotted with stream waters along or near a line connecting the snow and groundwater end-members. Thus, for seasonally snow-covered catchments from montane to alpine ecosystems, snowmelt infiltrates underlying soils before snowmelt recharges groundwater reservoirs and contributes to surface flows. Seasonally snow-covered catchments are not Teflon basins. Rather, snowmelt infiltrates soils where solute concentrations are changed by biological and geochemical processes.

  11. Multiple-method approaches for quantifying fine sediment dynamics in river catchments over contemporary timescales

    NASA Astrophysics Data System (ADS)

    Smith, Hugh

    2015-04-01

    Understanding the patterns and processes of contemporary fine sediment dynamics in river catchments constitutes a key research challenge for catchment scientists. Such knowledge has considerable value for the targeting of management resources to reduce excess fine sediment supply and its impacts on water resources and aquatic ecosystems. Many past studies tended to focus on a single compartment of the fine sediment cascade and utilised a limited range of research methods. For more holistic understanding, the use of multiple-method approaches is required to provide data on the sources, transfer, storage, and transit times of fine sediment in river catchments. Such approaches would allow scientists to better conceptualise catchment processes controlling the movement of fine sediment across a range of spatial scales. It may also enhance the scientific quality of catchment-scale studies through the acquisition of multiple lines of evidence concerning a particular research problem. The specific combination of fine sediment tracing and fingerprinting procedures with catchment sediment flux measurements and sediment budget modelling has considerable potential to enhance our knowledge of contemporary sediment dynamics. This combination of techniques offers complementary information and the opportunity to compare datasets, such as estimates of catchment sediment source contributions obtained using sediment tracers with direct measurements of sediment fluxes or catchment model outputs. This contribution explores the potential for such combinations of methods to yield distinctive insights not otherwise available from the use of only one of these techniques. It draws on published examples of multiple-method studies by the author from small agricultural and wildfire-affected forest catchments (1-2 km2) in south-east Australia and from larger agricultural river catchments (38-920 km2) in south-west England. It will also identify possible directions for catchment research based

  12. Nutrient cycling and the growth of benthic algae in experimentally acidified Little Rock Lake, WI

    SciTech Connect

    Detenbeck, N.E.

    1987-01-01

    Changes in nutrient-cycling and the growth of benthic algae resulting from decreased pH in low alkalinity lake systems were analyzed by laboratory, mesocosm, and whole-lake studies on Little Rock Lake, Wisconsin. Nutrients, transparency, an algal growth in the experimentally acidified basin were compared with conditions in an untreated reference basin. During the first summer following acidification (1985), accumulation rates of attached algae were significantly higher in the acidified basin than in the reference basin during June-August, but not in September. Color and winter silica values were significantly lower in the acidified basin relative to the reference basin following treatment. In addition, the lack of a fall decline in SiO/sub 2/ in the north basin in 1986 may signal pH-related changes in siliceous algal communities.

  13. The Impact of Flow on Spatial Variability of Streamwater Chemistry in a Boreal Catchment

    NASA Astrophysics Data System (ADS)

    Buffam, I.; Laudon, H.; Bishop, K.; Temnerud, J.; Mörth, M.

    2004-12-01

    Spatial variability in water chemistry is one defining characteristic of stream ecosystems. An infrequently studied aspect of this variability is the impact of flow regime: for instance, does the variation in water chemistry within a watershed differ between times of baseflow and flood? We examined this issue in Krycklan, a largely forested till-underlain boreal catchment in Northern Sweden, with an emphasis on changes occurring during the annual spring flood. Utilizing 15 stream sites ranging in catchment size from 0.07-68 km2 and in catchment wetland coverage from 0-40%, the between-site variance in several water parameters was compared between times of stable, relatively low flow and times of dramatically changing, high flow during spring flood. Distinctly different patterns were observed for different solutes. While dissolved organic carbon (DOC) varied widely between streams at baseflow (5-40 mg/l) and was positively correlated with catchment % wetland area, these differences were subdued during peak flood (DOC range 15-25 mg/l), and as such variability was lower. Conversely, differences in inorganic cation concentrations (electrical conductivity ranged from 15-30 μ S/cm) were amplified during the spring flood, resulting in increased spatial variability. Much of the change in variability hinged on the contrasting behavior of streams draining catchments with high % wetland compared to forested catchments: wetland streams had lower concentrations of cations at baseflow, and were also diluted more dramatically than forest streams during the flood. Hydrological flowpaths were explored using isotopic and chemical signatures of streamwater and catchment source waters. Much of the observed patterns in spatial variability could be explained by divergent flowpaths within wetland and forest catchments during spring flood, and by differing source areas for DOC vs. cations.

  14. Modelling The Variation of Sediment Yield With Catchment Area

    NASA Astrophysics Data System (ADS)

    Bathurst, J. C.; Birkinshaw, S. J.

    The SHETRAN physically-based model is used to investigate the variation of sed- iment yield with upstream area in a catchment. Modelling avoids the difficulties of studying variations with limited field data. It enables the variation to be considered on a nested basis (i.e. in a single catchment) rather than, as so often with field data, between different catchments. It also enables the controlling influences of land use, rainfall distribution and sediment source to be examined. Sediment yield is typically held to decrease as catchment area increases, as the river network becomes more re- mote from the headwater sediment sources. However, the opposite variation has also been reported. Model simulations with two catchments show that, with uniform veg- etation cover, sediment yield either decreases or is constant as area increases. The downstream decrease is accentuated if rainfall (and thence erosion) is higher in the headwaters than at lower elevations. Changing the land use so that erosion increases at lower elevations (e.g. upland forest, lowland wheat) can reverse the trend, so that sediment yield increases downstream. Limiting the sediment source to the river chan- nel (i.e. no hillslope supply) has the same effect. The results illustrate the effect of various controls on sediment yield and also demonstrate the usefulness of physically- based models in exploring the topic.

  15. Assessing catchment connectivity using hysteretic loops

    NASA Astrophysics Data System (ADS)

    Keesstra, Saskia; Masselink, Rens; Goni, Mikel; Campo, Miguel Angel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel

    2015-04-01

    ). On the other hand, Op (ca.1,700 ha) is covered with forest and pasture (cattle-breeding); while Ow (ca. 500 ha), a sub-watershed of the Op, is almost completely covered with forest. The predominant climate in Op/Ow is sub-Atlantic. Furthermore, antecedent conditions and event characteristics were analysed. The loops were compared quantitatively and qualitatively between catchments for similar events and within the catchments for events with different characteristics.

  16. Identifying hydrological responses of micro-catchments under contrasting land use in the Brazilian Cerrado

    NASA Astrophysics Data System (ADS)

    Nobrega, R. L. B.; Guzha, A. C.; Torres, G. N.; Kovacs, K.; Lamparter, G.; Amorim, R. S. S.; Couto, E.; Gerold, G.

    2015-09-01

    In recent decades, the Brazilian Cerrado biome has been affected by intense land-use change, particularly the conversion of natural forest to agricultural land. Understanding the environmental impacts of this land-use change on landscape hydrological dynamics is one of the main challenges in the Amazon agricultural frontier, where part of the Brazilian Cerrado biome is located and where most of the deforestation has occurred. This study uses empirical data from field measurements to characterize controls on hydrological processes from three first-order micro-catchments < 1 km2 in the Cerrado biome. These micro-catchments were selected on the basis of predominant land use including native cerrado vegetation, pasture grass with cattle ranching, and cash crop land. We continuously monitored precipitation, streamflow, soil moisture, and meteorological variables from October 2012 to September 2014. Additionally, we determined the physical and hydraulic properties of the soils, and conducted topographic surveys. We used these data to quantify the water balance components of the study catchments and to relate these water fluxes to land use, catchment physiographic parameters, and soil hydrophysical properties. The results of this study show that runoff coefficients were 0.27, 0.40, and 0.16 for the cerrado, pasture, and cropland catchments, respectively. Baseflow is shown to play a significant role in streamflow generation in the three study catchments, with baseflow index values of more than 0.95. The results also show that evapotranspiration was highest in the cerrado (986 mm yr-1) compared to the cropland (828 mm yr-1) and the pasture (532 mm yr-1). However, discharges in the cropland catchment were unexpectedly lower than that of the cerrado catchment. The normalized discharge was 55 % higher and 57 % lower in the pasture and cropland catchments, respectively, compared with the cerrado catchment. We attribute this finding to the differences in soil type and

  17. Lakes-paleolakes cascade system and its role in shaping the runoff and chemical properties of water in the young-glacial catchment - example from the Tuchola Pinewood Forest (Northern Poland)

    NASA Astrophysics Data System (ADS)

    Gierszewski, Piotr; Brykała, Dariusz; Kaszubski, Michał; Plessen, Birgit

    2016-04-01

    The impact of paleolake basins, filled up with organic mineral deposits, in the transformation of the chemical properties of the outflow is generally ignored. Defining their role and importance in the water and matter cycles is one of the objectives of the hydrological and hydrochemical monitoring, which has been run in the catchment of Lake Czechowskie since mid-2012. The axis of the Lake Czechowskie catchment is a hydrographical system made of river and lake sections. Lake sections are not only present-day lakes (Głęboczek and Czechowskie), but also basins of the lakes functioned in the past, which are now biogenic plains. Lake sections of the system are connected by short valley sections, mostly of a gap character. The size and variability of surface water runoff from the basin is mainly affected by groundwater and the size of evaporation. Stable groundwater table provides stability of the river discharge, even during the periods of significant precipitation deficit. Groundwater fluctuation ranges registered during the period from May 2012 to September 2015 were between 0.17 and 1.25 m. The smallest were in the deepest piezometers located in watershed areas, and the largest in the shallow groundwater of lake terraces. The small dynamics of the groundwater states is reflected by slight fluctuations of water levels in Lake Czechowskie, which in the analyzed period amounted 0.40 cm. The surface of paleolake Trzechowskie, cut by a system of drainage ditches, is the area where an essential part of the surface runoff from the monitored catchment is formed. Large water resources in this part of the catchment are evidenced by the specific runoff value, which amounts to 25 dm3s‑1km2. It is much larger than the whole basin specific runoff which reaches 11 dm3s‑1km2. The measurements showed that the average surface runoff from Lake Czechowskie in the analyzed period was 0,065 m3s‑1 and was similar to the size of the water influx via watercourses supplying the lake

  18. Lakes-paleolakes cascade system and its role in shaping the runoff and chemical properties of water in the young-glacial catchment - example from the Tuchola Pinewood Forest (Northern Poland)

    NASA Astrophysics Data System (ADS)

    Gierszewski, Piotr; Brykała, Dariusz; Kaszubski, Michał; Plessen, Birgit

    2016-04-01

    The impact of paleolake basins, filled up with organic mineral deposits, in the transformation of the chemical properties of the outflow is generally ignored. Defining their role and importance in the water and matter cycles is one of the objectives of the hydrological and hydrochemical monitoring, which has been run in the catchment of Lake Czechowskie since mid-2012. The axis of the Lake Czechowskie catchment is a hydrographical system made of river and lake sections. Lake sections are not only present-day lakes (Głęboczek and Czechowskie), but also basins of the lakes functioned in the past, which are now biogenic plains. Lake sections of the system are connected by short valley sections, mostly of a gap character. The size and variability of surface water runoff from the basin is mainly affected by groundwater and the size of evaporation. Stable groundwater table provides stability of the river discharge, even during the periods of significant precipitation deficit. Groundwater fluctuation ranges registered during the period from May 2012 to September 2015 were between 0.17 and 1.25 m. The smallest were in the deepest piezometers located in watershed areas, and the largest in the shallow groundwater of lake terraces. The small dynamics of the groundwater states is reflected by slight fluctuations of water levels in Lake Czechowskie, which in the analyzed period amounted 0.40 cm. The surface of paleolake Trzechowskie, cut by a system of drainage ditches, is the area where an essential part of the surface runoff from the monitored catchment is formed. Large water resources in this part of the catchment are evidenced by the specific runoff value, which amounts to 25 dm3s-1km2. It is much larger than the whole basin specific runoff which reaches 11 dm3s-1km2. The measurements showed that the average surface runoff from Lake Czechowskie in the analyzed period was 0,065 m3s-1 and was similar to the size of the water influx via watercourses supplying the lake. On

  19. Characterizing Runoff and Water Yield from Headwater Catchments in the Southern Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Safeeq, M.; Hunsaker, C. T.

    2015-12-01

    In a mediterranean climate where much of the annual precipitation falls during winter, the snow-capped Sierra Nevada serves as the primary source of dry season runoff that supports agriculture, industries, urban, and other ecosystems. Increased warming has led to significant reductions in mountain snowpack accumulation and earlier snowmelt throughout the western United States where most of the snow accumulates at temperatures near the freezing point. As a result, declines in dry season runoff magnitude, earlier runoff timing, and altered flood risk have been reported across the region. An important question in this context is, how to best manage forested catchments for water and other ecosystem services? We depict the differences in hydrologic response of ten catchments in the Kings River Experimental Watersheds (KREW) research project using continuous precipitation, snow, and runoff data during 2004-2014. The size of these catchments ranges from 50 to 475 ha, and they span a 600-m elevation range in the rain snow transitional zone. In terms of soil, Shaver and Gerle-Cagwin dominate the lower elevation Providence catchments, and Cagwin soils dominate the higher elevation Bull catchments. The majority of these catchments have southwest aspect, moderate average slope (i.e. <25%), and a well-developed drainage network with drainage density ranging from 4.6 to 10.1 km/km2. Bull catchments, on average, have higher runoff than the Providence catchments across all hydrologic signatures extracted from daily hydrographs. Mean annual runoff ranges between 281 to 408 mm in Providence and 436 to 656 mm in Bull catchments despite no significant difference in precipitation among KREW's four meteorological stations. However, high elevation Bull catchments receive significantly more precipitation as snow than the low elevation Providence catchments. The average runoff ratio ranges from 18% to as high as 43% among different catchments, indicating that the catchment

  20. Environmental care in agricultural catchments: Toward the communicative catchment

    NASA Astrophysics Data System (ADS)

    Martin, Peter

    1991-11-01

    Substantial land degradation of agricultural catchments in Australia has resulted from the importation of European farming methods and the large-scale clearing of land. Rural communities are now being encouraged by government to take responsibility for environmental care. The importance of community involvement is supported by the view that environmental problems are a function of interactions between people and their environment. It is suggested that the commonly held view that community groups cannot care for their resources is due to inappropriate social institutions rather that any inherent disability in people. The communicative catchment is developed as a vision for environmental care into the future. This concept emerges from a critique of resource management through the catchment metaphors of the reduced, mechanical, and the complex, evolving catchment, which reflect the development of systemic and people-centered approaches to environmental care. The communicative catchment is one where both community and resource managers participate collaboratively in environmental care. A methodology based on action research and systemic thinking (systemic action research) is proposed as a way of moving towards the communicative catchment of the future. Action research is a way of taking action in organizations and communities that is participative and informed by theory, while systemic thinking takes into account the interconnections and relationships between social and natural worlds. The proposed vision, methodology, and practical operating principles stem from involvement in an action research project looking at extension strategies for the implementation of total catchment management in the Hunter Valley, New South Wales.

  1. Assessing the drivers of dissolved organic matter export from two contrasting lowland catchments, U.K.

    PubMed

    Yates, Christopher A; Johnes, Penny J; Spencer, Robert G M

    2016-11-01

    Two lowland catchments in the U.K. were sampled throughout 2010-11 to investigate the dominant controls on dissolved organic matter quantity and composition. The catchments had marked differences in terms of nutrient status, land cover and contrasting lithologies resulting in differences in the dominant flow pathways (groundwater vs. surface water dominated). The Upper Wylye is a chalk stream with a baseflow index of 0.98, draining a catchment dominated by intensive agricultural production. Millersford Brook is a lowland peat catchment with a baseflow index of 0.43, draining a semi-natural catchment with heather moorland and coniferous forest. Samples were collected weekly between October 2010 and September 2011 from eleven sampling locations. Samples were analysed to determine dissolved organic carbon, nitrogen and phosphorus fractions with DOM composition evaluated via the DOC:DON ratio, DOC:DOP ratio, specific UV absorption at 254nm, absorbance ratio (a250:a365) and the spectral slope parameter between 350 and 400nm (S350-400). Significant differences were observed in all determinands between the catchments, over time, and spatially along nutrient enrichment and geoclimatic gradients. Seasonal variation in preferential flow pathways mobilising groundwater-derived DOM were identified as likely controls on the delivery of DOM in the permeable chalk dominated catchment. Steeper S350-400 values and elevated a250:a365 ratios in this catchment suggest material of a lower bulk aromatic C content and molecular weight delivered during the winter months when compared to the summer. DOC:DON ratios were markedly lower in the chalk catchment than the peatland catchment, reflecting the paucity of organic matter within the mineral soils of the chalk landscape, and higher fertiliser application rates. This manuscript highlights that DOM composition varies according to catchment landscape character and hydrological function. PMID:27422728

  2. The chemical behavior of acidified chromium (3) solutions. B.S. Thesis

    NASA Technical Reports Server (NTRS)

    Terman, D. K.

    1981-01-01

    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)).

  3. Production performance and physiological responses of Angora goat kids fed acidified milk replacer.

    PubMed

    Sahlu, T; Carneiro, H; el Shaer, H M; Fernandez, J M

    1992-06-01

    Angora kids were blocked by birth weight and sex and assigned randomly to goat milk or acidified milk replacer. Daily milk intake, weekly BW, and heart girth measurements, and blood parameters (packed cell volume, total protein, glucose, and NEFA) were monitored at 3 d (initial) and at 4, 6, 8, and 9 wk of age. Both groups were fed their respective milks for ad libitum intake for 6 wk and then reduced to 75, 50, 25, and 0% of wk-6 intake during wk 7, 8, 9, and 10, respectively. Solid feed (20% CP and 3.1. Mcal of metabolizable energy/kg of DM) was provided for ad libitum intake starting on wk 3. Pretreatment BW (average 2.4 kg) and blood parameters were similar for milk and replacer groups. Packed cell volume (21.8 and 34.2%), total protein (50.3 and 46.6 g/L), and NEFA (.52 and .69 meq/L) for goat milk and acidified milk replacer groups, respectively, were affected by dietary treatment. Final BW (average 10.5 kg) and mean plasma glucose concentration (84 to 88 mg/dl) were similar between treatments; however, kids fed goat milk produced more mohair (13.8%) than those fed acidified milk replacer. Despite physiological differences, acidified milk replacer can be used successfully to raise Angora kids.

  4. Quality evaluation of packaged acidified vegetables subjected to continuous microwave pasteurization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study evaluated the use of 915 MHz continuous microwave processing with a rotation apparatus for pasteurization of acidified vegetable packages. Broccoli florets, and 1.2 cm cubes of broccoli stems, red bell pepper, and sweetpotato were pre-equilibrated to 1 g/100 g NaCl and 0.38 g/100 mL citric...

  5. The Reaction between Iron(II) Iodide and Potassium Dichromate(VI) in Acidified Aqueous Solution

    ERIC Educational Resources Information Center

    Talbot, Christopher

    2013-01-01

    This "Science note" teaching lesson explores the possible reaction between the ions in a reaction mixture consisting of iron(II) iodide and potassium dichromate(VI) in acidified aqueous solution. The electrode potentials will be used to deduce any spontaneous reactions under standard thermodynamic conditions (298 K, 1 bar (approximately…

  6. Economic reduction of acidifying deposition in Finland by decreasing emissions in Finland, Estonia and Russia.

    PubMed

    Tähtinen, M; Lehtilä, A; Pipatti, R; Wistbacka, M; Savolainen, I

    1997-09-26

    Here we consider cost-effective solutions of emission control measures in Finland and the nearby areas of Estonia, St. Petersburg region, Karelia and Kola, in order to limit the acidifying deposition in Finland. In the study, the emission control costs of SO2, NOx and NH3 are assessed for the areas studied and an optimisation model developed for calculation of cost-optimal deposition control policies. The input data of the model consist of the cost functions describing the emission control costs to achieve lower emission levels for the gases and areas considered and of dispersion coefficients which describe the deposition due to an emission source in the deposition receptor grid squares. In addition, the model includes a description to calculate the acidifying load. The optimisation is based on linear programming. When the acidifying load of Southern Finland is reduced by minimising the total control costs, approx, three quarters of the total control costs are due to measures in the nearby areas, Estonia, St. Peterburg region, Karelia and Kola, and approx. one quarter due to measures in Finland. The distribution of costs in the cost-optimised cases depends relatively little on the level to which the acidifying load due the source areas considered are required to be reduced. If the load reduction target is moderate, the emission control measures should mainly be allocated to sulphur emissions and to some extent to ammonia emissions and, if the load reduction target is stricter, also to the emissions of nitrogen oxides.

  7. Survival of Mycobacterium avium and Mycobacterium tuberculosis in Acidified Vacuoles of Murine Macrophages

    PubMed Central

    Gomes, Maria Salomé; Paul, Simon; Moreira, Andre L.; Appelberg, Rui; Rabinovitch, Michel; Kaplan, Gilla

    1999-01-01

    Despite the antimicrobial mechanisms of vertebrate phagocytes, mycobacteria can survive within the phagosomes of these cells. These organisms use various strategies to evade destruction, including inhibition of acidification of the phagosome and inhibition of phagosome-lysosome fusion. In contrast to mycobacteria, Coxiella burnetii, the etiologic agent of Q fever, inhabits a spacious acidified intracellular vacuole which is prone to fusion with other vacuoles of the host cell, including phagosomes containing mycobacteria. The Coxiella-infected cell thus provides a unique model for investigating the survival of mycobacteria in an acidified phagosome-like compartment. In the present study, murine bone marrow-derived macrophages were infected with either Mycobacterium avium or Mycobacterium tuberculosis and then coinfected with C. burnetii. We observed that the majority of phagocytosed mycobacteria colocalized to the C. burnetii-containing vacuole, which maintained its acidic properties. In coinfected macrophages, the growth of M. avium was not impaired following fusion with the acidified vacuole. In contrast, the growth rate of M. tuberculosis was reduced in acidified vacuoles. These results suggest that although both species of mycobacteria inhibit phagosome-lysosome fusion, they may be differentially susceptible to the toxic effects of the acidic environment in the mature phagolysosome. PMID:10377091

  8. Deriving N-year discharges in small catchments

    NASA Astrophysics Data System (ADS)

    Ledvinka, Ondrej; Bohac, Milon

    2016-04-01

    Maximum discharges with the return period of 100 years (Q100) belong to basic hydrological data that are derived and provided for any profile of the river network by the Czech Hydrometeorological Institute (CHMI). However, as regards small catchments, the determination of these characteristics is largely subjective and thus it is rather performed by comparing the results of several methods. The first approach is to extrapolate the three parameters of maximum peak discharges (average Qmax, coefficient of variation Cvmax, Q100) from water-gauging stations to selected unobserved profiles (using regression relationships and regularities at the confluence points). For this purpose, the so-called program Budsez is utilized. During this process, the physical-geographical (PG) features, rainfall data and other information about catchments are considered, based on which the parameters of theoretical distributions of N-year discharges are optimized. For smaller catchments the relationships between the 100-year specific runoff q100 and the catchment area and other PG characteristics are used that are determined in a GIS environment with the extension AGPosudek. In this innovative method, besides many other PG characteristics, especially the average value of CN and N-year maximum daily precipitation are taken into account when computing Q100. In the older methodologies, Q100 is based on the average slope of the stream and the average slope of the catchment. The values of Q100 are then corrected according to the percentage of forested areas and the catchment shape. Hydrologists compare the values of Q100 coming from different approaches in a logarithmic graph (q100 against area) for the particular catchment or its analogon. The final value is determined with respect to experience and previously issued values. The remaining N-year discharges are usually assessed through the ratio QN/Q100 from the nearest water-gauging station or the closest profile where these ratios were

  9. Dust in an acidified ocean: iron bioavailability, phytoplankton growth and DMS

    NASA Astrophysics Data System (ADS)

    Mélançon, J.; Levasseur, M.; Lizotte, M.; Scarratt, M. G.; Tremblay, J. E.; Tortell, P. D.; Yang, G.; Shi, G. Y.; Gao, H.; Semeniuk, D.; Robert, M.; Arychuk, M.; Johnson, K.; Sutherland, N.; Davelaar, M.; Nemcek, N.; Pena, A.; Richardson, W.

    2015-12-01

    Ocean acidification (OA) is likely to have an effect on the fertilizing potential of desert dust in high-nutrient, low-chlorophyll oceanic regions, either by modifying Fe speciation and bioavailability, or by altering phytoplankton Fe requirements and acquisition. To address this issue, short incubations (4 days) of northeast subarctic Pacific waters enriched with either FeSO4 or dust, and maintained at pH 8.0 (in situ) and 7.8 were conducted in August 2010. We assessed the impact of a decrease in pH on dissolved Fe concentration, phytoplankton biomass, taxonomy and productivity, and the production of dimethylsulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP). Chlorophyll a (chl a) remained unchanged in the controls and doubled in both the FeSO4-enriched and dust-enriched incubations, confirming the Fe-limited status of the plankton assemblage during the experiment. In the acidified treatments, a significant reduction (by 16-38%) of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15% reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. Lowering the pH affected mostly the haptophytes, but pelagophyte concentrations were also reduced in some acidified treatments. Acidification did not significantly alter DMSP and DMS concentrations. These results show that dust deposition events in a low-pH iron-limited Northeast subarctic Pacific are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean during the few days following fertilization and point to a low initial sensitivity of the DMSP and DMS dynamics to OA.

  10. Fish mortality during sea salt episodes--catchment liming as a countermeasure.

    PubMed

    Teien, Hans-Christian; Salbu, Brit; Heier, Lene S; Kroglund, Frode; Rosseland, Bjørn Olav

    2005-10-01

    Aluminium (Al) toxicity is usually associated with acid rain and acidified freshwater systems. The present work demonstrates that acute fish mortality (50%) also occurs in moderate acidified salmon rivers during sea salt episodes. Furthermore, catchment liming was proved to be an efficient measure to counteract the fish toxicity. The impact of sea salt episodes on river water qualities and on Atlantic Salmon (Salmo salar L.) was studied in two rivers situated at the west coast of Norway. During February-May 2002, fish were kept in tanks and continually exposed to the changing water qualities. Changes in Al-species were followed using in situ fractionation techniques. During storm events and high sea salt deposition, the sea salt concentration increased (190 to 580 microM Cl), pH decreased (pH 5.3 to 4.6) and the concentration of low molecular mass (LMM) cationic Al-species (Al(i)) increased (0.7 to 3.0 microM) in the river. Subsequently, Al accumulated in fish gills (6 to 19 micromol g(-1) dw) causing ionoregulatory and respiratory failures as well as mortality. In water the concentration of LMM Al(i) stayed enhanced during four weeks, while the physiological stress responses in surviving fish remained high for a longer time (>eight weeks). To counteract Al toxicity, one of the tributary catchments had been limed four years earlier. Due to catchment liming (1000 kg ha(-1)) the water concentration of LMM Al(i)(<0.7 microM) and the Al accumulation in gills remained relatively low (<7 micromol g(-1) dw) during the storm and no fish mortality occurred.

  11. Fish mortality during sea salt episodes--catchment liming as a countermeasure.

    PubMed

    Teien, Hans-Christian; Salbu, Brit; Heier, Lene S; Kroglund, Frode; Rosseland, Bjørn Olav

    2005-10-01

    Aluminium (Al) toxicity is usually associated with acid rain and acidified freshwater systems. The present work demonstrates that acute fish mortality (50%) also occurs in moderate acidified salmon rivers during sea salt episodes. Furthermore, catchment liming was proved to be an efficient measure to counteract the fish toxicity. The impact of sea salt episodes on river water qualities and on Atlantic Salmon (Salmo salar L.) was studied in two rivers situated at the west coast of Norway. During February-May 2002, fish were kept in tanks and continually exposed to the changing water qualities. Changes in Al-species were followed using in situ fractionation techniques. During storm events and high sea salt deposition, the sea salt concentration increased (190 to 580 microM Cl), pH decreased (pH 5.3 to 4.6) and the concentration of low molecular mass (LMM) cationic Al-species (Al(i)) increased (0.7 to 3.0 microM) in the river. Subsequently, Al accumulated in fish gills (6 to 19 micromol g(-1) dw) causing ionoregulatory and respiratory failures as well as mortality. In water the concentration of LMM Al(i) stayed enhanced during four weeks, while the physiological stress responses in surviving fish remained high for a longer time (>eight weeks). To counteract Al toxicity, one of the tributary catchments had been limed four years earlier. Due to catchment liming (1000 kg ha(-1)) the water concentration of LMM Al(i)(<0.7 microM) and the Al accumulation in gills remained relatively low (<7 micromol g(-1) dw) during the storm and no fish mortality occurred. PMID:16193171

  12. Potential acidifying capacity of deposition experiences from regions with high NH4+ and dry deposition in China.

    PubMed

    Vogt, Rolf D; Seip, Hans Martin; Larssen, Thorjørn; Zhao, Dawei; Xiang, Renjun; Xiao, Jinsong; Luo, Jiahai; Zhao, Yu

    2006-08-15

    Acid rain may cause soil acidification possibly leading to indirect forest damage. Assessment of acidification potential of atmospheric deposition is problematic where dry and occult deposition is significant. Furthermore, uncertainty is enhanced where a substantial part of the potential acidity is represented by deposition of ammonium (NH(4)(+)) since the degree of assimilation and nitrification is not readily available. Estimates of dry deposition based on deposition velocity are highly uncertain and the models need to be verified or calibrated by field measurements of total deposition. Total deposition may be monitored under the forest canopy. The main problem with this approach is the unknown influence of internal bio-cycling. Moreover, bio-cycling may neutralize much of the acidity by leaching of mainly K(+). When the water percolates down into the rooting zone this K(+) is assimilated again and acidity is regenerated. Most monitoring stations only measure deposition. Lacking measurements of output flux of both NH(4)(+) and NO(3)(-) from the soil one cannot assess current net N transformation rates. Assumptions regarding the fate of ammonium in the soil have strong influence on the estimated acid load. Assuming that all the NH(4)(+) is nitrified may lead to an overestimation of the acidifying potential. In parts of the world where dry deposition and ammonium are important special consideration of these factors must be made when assessing the acidification potential of total atmospheric loading. In China dry and occult deposition is considerable and often greater than wet deposition. Furthermore, the main part of the deposited N is in its reduced state (NH(4)(+)). The IMPACTS project has monitored the water chemistry as it moves through watersheds at 5 sites in China. This paper dwells at two important findings in this study. 1) Potassium leached from the canopy by acid rain is assimilated again upon entering the mineral soil. 2) Nitrification apparently mainly

  13. The catchment based approach using catchment system engineering

    NASA Astrophysics Data System (ADS)

    Jonczyk, Jennine; Quinn, Paul; Barber, Nicholas; Wilkinson, Mark

    2015-04-01

    The catchment based approach (CaBa) has been championed as a potential mechanism for delivery of environmental directives such as the Water Framework Directive in the UK. However, since its launch in 2013, there has been only limited progress towards achieving sustainable, holistic management, with only a few of examples of good practice ( e.g. from the Tyne Rivers trust). Common issues with developing catchment plans over a national scale include limited data and resources to identify issues and source of those issues, how to systematically identify suitable locations for measures or suites of measures that will have the biggest downstream impact and how to overcome barriers for implementing solutions. Catchment System Engineering (CSE) is an interventionist approach to altering the catchment scale runoff regime through the manipulation of hydrological flow pathways throughout the catchment. A significant component of the runoff generation can be managed by targeting hydrological flow pathways at source, such as overland flow, field drain and ditch function, greatly reducing erosive soil losses. Coupled with management of farm nutrients at source, many runoff attenuation features or measures can be co-located to achieve benefits for water quality and biodiversity. A catchment, community-led mitigation measures plan using the CSE approach will be presented from a catchment in Northumberland, Northern England that demonstrate a generic framework for identification of multi-purpose features that slow, store and filter runoff at strategic locations in the landscape. Measures include within-field barriers, edge of field traps and within-ditch measures. Progress on the implementation of measures will be reported alongside potential impacts on the runoff regime at both local and catchment scale and costs.

  14. Suspended sediment apportionment in a South-Korean mountain catchment

    NASA Astrophysics Data System (ADS)

    Birkholz, Axel; Meusburger, Katrin; Park, Ji-Hyung; Alewell, Christine

    2016-04-01

    Due to the rapid agricultural expansion and intensification during the last decades in South-Korea, large areas of hill slope forests were transformed to paddies and vegetable fields. The intensive agriculture and the easily erodible soils in our catchment are a major reason for the increased erosion causing suspended sediments to infiltrate into the close drinking water reservoir. The drinking water reservoir Lake Soyang provides water supply for over ten million people in Seoul. Landscape managers need to know the exact origin of these sediments before they can create landscape amelioration schemes. We applied a compound-specific stable isotope (CSSI) approach (Alewell et al., 2015) to apportion the sources of the suspended sediments between forest and agricultural soil contribution to the suspended sediments in a different catchment and applied the same approach to identify and quantify the different sources of the suspended sediments in the river(s) contributing to Lake Soyang. We sampled eight soil sites within the catchment considering the different landuse types forest, rice paddies, maize and vegetables. Suspended sediments were sampled at three outlets of the different sub-catchments. Soils and suspended sediments are analysed for bulk carbon and nitrogen isotopes, compound-specific carbon isotopes of plant-wax derived long-chain fatty acids and long-chain n-alkanes. Fatty acid and alkane isotopes are then used in mixing calculations and the mixing model software IsoSource to find out the contribution of the different source soils to the suspended sediments. We present first data of the source soils and the suspended sediments. C. Alewell, A. Birkholz, K. Meusburger, Y. Schindler-Wildhaber, L. Mabit, 2015. Sediment source attribution from multiple land use systems with CSIA. Biogeosciences Discuss. 12: 14245-14269.

  15. Quantifying the effects of human impact on sediment yield for European catchments

    NASA Astrophysics Data System (ADS)

    Vanmaercke, M.; Poesen, J.; Govers, G.; Verstraeten, G.; Kettner, A.; Van Den Eeckhaut, M.

    2012-04-01

    Both from a scientific and environmental management perspective, there is a great need to better assess the magnitude of human impacts on catchment sediment yield (SY, t/km2/y) and to identify the factors that control this magnitude. Quantification of these impacts is generally impeded by the lack of reliable SY data under "pristine" conditions, i.e. before the catchment was affected by humans in terms of land use or reservoirs. Based on a dataset with SY-measurements from 146 mainly forested catchments in Europe that were not affected by reservoirs, a regression model was developed. This model allows estimating pristine SY, based on the catchment topography, lithology and the degree of seismic activity (as indicated on earthquake hazard maps). Validation of this model indicated that this model is fairly robust, while 95% of the predicted SY-values deviate less than one order of magnitude from their measured SY-value. Hence, the application of this model to a large (> 400) number of European catchments for which measured actual, i.e. "disturbed", SY-data were available allowed to quantify the effects of human impact on SY and their controlling factors. It was found that catchment area has a strong control on catchment sensitivity to human impact. Whereas in small (< 1 km2) disturbed catchments actual SY can be up to 100 times higher than their modeled pristine SY-value, a clear human impact is generally difficult to detect for catchments > 100 km2. Furthermore, a clear positive relationship between the degree of SY disturbance (i.e. the ratio between the actual and the pristine SY) and the fraction of disturbed land use in the catchment was noted. Catchments with a high fraction of arable land (> 50%) also showed a more distinctive decrease in the degree of disturbance with increasing catchment area. However, the form of this relationship is also controlled by other factors, such as catchment lithology. The relation between the degree of disturbance and the

  16. Effects of land cover change on evapotranspiration and streamflow of small catchments in the Upper Xingu River Basin, Central Brazi

    NASA Astrophysics Data System (ADS)

    Costa, M. H.; Dias, L. C. P.; Macedo, M.; Coe, M. T.; Neill, C.

    2014-12-01

    This study assess the influence of land cover changes on evapotranspiration and streamflow in small catchments in the Upper Xingu River Basin (Mato Grosso state, Brazil). Streamflow was measured in catchments with uniform land use for September 1, 2008 to August 31, 2010. We used models to simulate evapotranspiration and streamflow for the four most common land cover types found in the Upper Xingu: tropical forest, cerrado (savanna), pasture, and soybean croplands. We used INLAND to perform single point simulations considering tropical rainforest, cerrado and pasturelands, and AgroIBIS for croplands. Converting natural vegetation to agriculture substantially modifies evapotranspiration and streamflow in small catchments. Measured mean streamflow in soy catchments was about three times greater than that of forest catchments, while the mean annual amplitude of flow in soy catchments was more than twice that of forest catchments. Simulated mean annual evapotranspiration was 39% lower in agricultural ecosystems (pasture and soybean cropland) than in natural ecosystems (tropical rainforest and cerrado). Observed and simulated mean annual streamflows in agricultural ecosystems were more than 100% higher than in natural ecosystems. The accuracy of the simulations is improved by using field-measured soil hydraulic properties. The inclusion of local measurements of key soil parameters is likely to improve hydrological simulations in other tropical regions.

  17. Effects of land cover change on evapotranspiration and streamflow of small catchments in the Upper Xingu River Basin, Central Brazi

    NASA Astrophysics Data System (ADS)

    Costa, M. H.; Dias, L. C. P.; Macedo, M.; Coe, M. T.; Neill, C.

    2015-12-01

    This study assess the influence of land cover changes on evapotranspiration and streamflow in small catchments in the Upper Xingu River Basin (Mato Grosso state, Brazil). Streamflow was measured in catchments with uniform land use for September 1, 2008 to August 31, 2010. We used models to simulate evapotranspiration and streamflow for the four most common land cover types found in the Upper Xingu: tropical forest, cerrado (savanna), pasture, and soybean croplands. We used INLAND to perform single point simulations considering tropical rainforest, cerrado and pasturelands, and AgroIBIS for croplands. Converting natural vegetation to agriculture substantially modifies evapotranspiration and streamflow in small catchments. Measured mean streamflow in soy catchments was about three times greater than that of forest catchments, while the mean annual amplitude of flow in soy catchments was more than twice that of forest catchments. Simulated mean annual evapotranspiration was 39% lower in agricultural ecosystems (pasture and soybean cropland) than in natural ecosystems (tropical rainforest and cerrado). Observed and simulated mean annual streamflows in agricultural ecosystems were more than 100% higher than in natural ecosystems. The accuracy of the simulations is improved by using field-measured soil hydraulic properties. The inclusion of local measurements of key soil parameters is likely to improve hydrological simulations in other tropical regions.

  18. SWAT-CS: Revision and testing of SWAT for Canadian Shield catchments

    NASA Astrophysics Data System (ADS)

    Fu, Congsheng; James, April L.; Yao, Huaxia

    2014-04-01

    Canadian Shield catchments are under increasing pressure from various types of development (e.g., mining and increased cottagers) and changing climate. Within the southern part of the Canadian Shield, catchments are generally characterized by shallow forested soils with high infiltration rates and low bedrock infiltration, generating little overland flow, and macropore and subsurface flow are important streamflow generation processes. Large numbers of wetlands and lakes are also key physiographic features, and snow-processes are critical to catchment modeling in this climate. We have revised the existing, publicly available SWAT (version 2009.10.1 Beta 3) to create SWAT-CS, a version representing hydrological processes dominating Canadian Shield catchments, where forest extends over Precambrian Shield bedrock. Prior to this study, very few studies applying SWAT to Canadian Shield catchments exist (we have found three). We tested SWAT-CS using the Harp Lake catchment dataset, an Ontario Ministry of Environment research station located in south-central Ontario. Simulations were evaluated against 30 years of observational data, including streamflow from six headwater sub-catchments (0.1-1.9 km2), outflow from Harp Lake (5.4 km2) and five years of weekly snow water equivalent (SWE). The best Nash-Sutcliffe efficiency (NSE) results for daily streamflow calibration, daily streamflow validation, and SWE were 0.60, 0.65, and 0.87, respectively, for sub-catchment HP4 (with detailed land use and soil data). For this range of catchment scales, land cover and soil properties were found to be transferable across sub-catchments with similar physiographic features, namely streamflow from the remaining five sub-catchments could be modeled well using sub-catchment HP4 parameterization. The Harp Lake outflow was well modeled using the existing reservoir-based target release method, generating NSEs of 0.72 and 0.67 for calibration and verification periods respectively. With

  19. Evaluating stream water quality through land use analysis in two grassland catchments: impact of wetlands on stream nitrogen concentration.

    PubMed

    Hayakawa, A; Shimizu, M; Woli, K P; Kuramochi, K; Hatano, R

    2006-01-01

    We evaluated the impacts of natural wetlands and various land uses on stream nitrogen concentration in two grassland-dominated catchments in eastern Hokkaido, Japan. Analyzing land use types in drainage basins, measuring denitrification potential of its soil, and water sampling in all seasons of 2003 were performed. Results showed a highly significant positive correlation between the concentration of stream NO3-N and the proportion of upland area in drainage basins in both catchments. The regression slope, which we assumed to reflect the impact on water quality, was 24% lower for the Akkeshi catchment (0.012 +/- 0.001) than for the Shibetsu catchment (0.016 +/- 0.001). In the Akkeshi catchment, there was a significant negative correlation between the proportion of wetlands in the drainage basins and stream NO3-N concentration. Stream dissolved organic nitrogen (DON) and carbon (DOC) concentrations were significantly higher in the Akkeshi catchment. Upland and urban land uses were strongly linked to increases in in-stream N concentrations in both catchments, whereas wetlands and forests tended to mitigate water quality degradation. The denitrification potential of the soils was highest in wetlands, medium in riparian forests, and lowest in grasslands; and was significant in wetlands and riparian forests in the Akkeshi catchment. The solubility of soil organic carbon (SOC) and soil moisture tended to determine the denitrification potential. These results indicate that the water environment within the catchments, which influences denitrification potential and soil organic matter content, could have caused the difference in stream water quality between the two catchments. PMID:16510707

  20. Evaluating stream water quality through land use analysis in two grassland catchments: impact of wetlands on stream nitrogen concentration.

    PubMed

    Hayakawa, A; Shimizu, M; Woli, K P; Kuramochi, K; Hatano, R

    2006-01-01

    We evaluated the impacts of natural wetlands and various land uses on stream nitrogen concentration in two grassland-dominated catchments in eastern Hokkaido, Japan. Analyzing land use types in drainage basins, measuring denitrification potential of its soil, and water sampling in all seasons of 2003 were performed. Results showed a highly significant positive correlation between the concentration of stream NO3-N and the proportion of upland area in drainage basins in both catchments. The regression slope, which we assumed to reflect the impact on water quality, was 24% lower for the Akkeshi catchment (0.012 +/- 0.001) than for the Shibetsu catchment (0.016 +/- 0.001). In the Akkeshi catchment, there was a significant negative correlation between the proportion of wetlands in the drainage basins and stream NO3-N concentration. Stream dissolved organic nitrogen (DON) and carbon (DOC) concentrations were significantly higher in the Akkeshi catchment. Upland and urban land uses were strongly linked to increases in in-stream N concentrations in both catchments, whereas wetlands and forests tended to mitigate water quality degradation. The denitrification potential of the soils was highest in wetlands, medium in riparian forests, and lowest in grasslands; and was significant in wetlands and riparian forests in the Akkeshi catchment. The solubility of soil organic carbon (SOC) and soil moisture tended to determine the denitrification potential. These results indicate that the water environment within the catchments, which influences denitrification potential and soil organic matter content, could have caused the difference in stream water quality between the two catchments.

  1. Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments

    NASA Astrophysics Data System (ADS)

    Reader, H. E.; Stedmon, C. A.; Kritzberg, E. S.

    2014-01-01

    To examine the potential influence of terrestrially derived DOM on the Baltic Sea, a year-long study of dissolved organic matter (DOM) was performed in three river catchments in Sweden. One catchment drains into the Bothnian Sea, while two southern catchments drain into the Baltic Proper. Dissolved organic carbon (DOC) concentrations were positively correlated with discharge from forested catchments over the year and while the overall concentrations of DOC were several times higher in the southern two catchments, annual loading of DOC was on the same order for all three catchments, due to differences in discharge. Biological oxygen demand (BOD) was used as a proxy for the lability of carbon in the system. The range of BOD values was similar for all three catchments, however, the ratio of BOD to DOC (an indication of the labile fraction) in Ume älv was four times higher than in the southern two catchments. Total annual BOD loading to the Baltic Sea was twice as high in the northern catchment. Lower winter temperatures and preservation of organic matter in the northern catchment combined with an intense spring flood help to explain the higher concentrations of labile carbon in the northern catchment. Lower lability of DOM as well as higher colour in the southern catchments suggest that wetlands (i.e. peat bogs) may be the dominant source of DOM in these catchments, particularly in periods of low flow. With climate change expected to increase precipitation events and temperatures across the region, the supply and quality of DOM delivered to the Baltic Sea can also be expected to change. Our results indicate that DOM supply will be more stable throughout the year, and potentially have a lower bioavailability.

  2. Effect of Sweet Orange Fruit Waste Diets and Acidifier on Haematology and Serum Chemistry of Weanling Rabbits

    PubMed Central

    Daudu, Oluremi Martha; Sani, Rahamatu Usman; Adedibu, Iyetunde Ifeyori; Ademu, Lawrence Anebi; Bawa, Gideon Shaibu; Olugbemi, Taiye Sunday

    2014-01-01

    A total of thirty-five mixed breed (35) rabbits of average weight of 700 g aged 5-6 weeks were allocated to seven treatments in a completely randomised design to investigate the effect of sweet orange fruit waste (SOFW) and acidomix acidifier on haematology and serum chemistry. The diets were 0% SOFW, 10% SOFW with 0.5% acidomix, 10% SOFW with 0.7 acidomix, 15% SOFW with 0.5% acidifier, 15% SOFW with 0.7% acidifier, 20% SOFW with 0.5% acidifier, and 20% SOFW with 0.7% acidifier. Blood samples were analyzed for haemoglobin (hb) concentration, white blood cells (WBC), red blood cells (RBC), differential WBC count (lymphocyte, basophil, eosinophil, monocyte, and neutrophil), alanine amino transferase (ALT), alkaline phosphatase (ALP), aspartate amino transferase (AST), total protein, albumin, and globulin. There was no interaction between SOFW and acidifier for the haematological and most of the serum chemistry parameters but significant difference was observed in ALT; however the values were within the normal range. SOFW had no significant effect on all haematological and serum chemistry parameters. Acidomix had significant effect (P < 0.05) on haemoglobin concentration; rabbits fed 0.5% acidomix diets had higher values which were within the normal range. It is therefore concluded that SOFW with acidifier up to 20% had no detrimental effect on serum chemistry and haematology. PMID:26464931

  3. Isotopic fingerprints in a nested catchment setup with contrasting landscape properties

    NASA Astrophysics Data System (ADS)

    Klaus, Julian; Pfister, Laurent

    2016-04-01

    Physiographic characteristics control how catchments store, mix, and release water. These catchment properties, together with the hydro-meteorological conditions, also influence the transformation of the stable isotopic signal from precipitation to stream discharge. Several studies showed that catchments often exhibit a lower slope of the regression line between δOxygen-18 and δDeuterium of streamwater (Stream Evaporation Water Lines: SEWL) compared to the Local Meteoric Water Line (LMWL). We hypothesise that the combination of land use, geology, and topography is controlling the differences between the LMWL and SEWL. We test this in the nested river setup of the Attert catchment (250 sqkm), with 9 sub-catchment ranging from 0.45 sqkm to 161 sqkm. The different sub-catchments show remarkable different catchment characteristics in terms of geology and land use, while the hydro-meteorological forcing is rather uniform between the sub-catchments. We found that an elevation effect strongly controls the differences in mean δOxygen-18 and δDeuterium of streamflow between the catchments (-1.2‰ δD/100 m). Streamflow also shows remarkable evaporative enrichment, the slopes of the SEWL ranges from 3.2 to 5.1. Increasing fractions of sandstone geology and forest cover generally lead to lower slopes of the SEWL, while the extent of alluvial floodplain leads to slopes more similar to the MEWL. This contribution shows how different catchment properties influence the relationship δOxygen-18 and δDeuterium that is generally controlled by non-kinetic fractionation. Further work on the processes that lead to different slopes of the SEWL is needed.

  4. Hydrogeomorphological and water quality impacts of oil palm conversion and logging in Sabah, Malaysian Borneo: a multi-catchment approach

    NASA Astrophysics Data System (ADS)

    Walsh, Rory; Nainar, Anand; Bidin, Kawi; Higton, Sam; Annammala, Kogilavani; Blake, William; Luke, Sarah; Murphy, Laura; Perryman, Emily; Wall, Katy; Hanapi, Jamil

    2016-04-01

    The last three decades have seen a combination of logging and land-use change across most of the rainforest tropics. This has involved conversion to oil palm across large parts of SE Asia. Although much is now known about the hydrological and sediment transport impacts of logging, relatively little is known about how impacts of oil palm conversion compare with those of logging. Furthermore little is known about the impacts of both on river morphology and water quality. This paper reports some findings of the first phase of a ten-year large-scale manipulative multi-catchment experiment (part of the SAFE - Stability of Altered Forest Ecosystems - Project), based in the upper part of the Brantian Catchment in Sabah, Malaysian Borneo; the project is designed to assess the degree to which adverse impacts of oil palm conversion (on erosion, downstream channel change, water quality and river ecology) might be reduced by retaining buffer zones of riparian forest of varying width from zero to 120 metres. Ten 2 km2 catchments of contrasting land use history have been instrumented since 2011 to record discharge, turbidity, conductivity and water temperature at 5-minute intervals. These comprise 6 repeat-logged catchments being subjected in 2015-16 to conversion to oil palm with varying riparian forest widths; a repeat-logged 'control' catchment; an old regrowth catchment; an oil palm catchment; and a primary forest catchment. In addition, (1) monthly water samples from the catchments have been analysed for nitrates and phosphates, (2) channel cross-sectional change along each stream has been monitored at six-monthly intervals and (3) supplementary surveys have been made of downstream bankfull channel cross-sectional size and water chemistry at a wider range of catchment sites, and (4) sediment cores have been taken and contemporary deposition monitored at a hierarchical network of sites in the large Brantian catchment for geochemical analysis and dating to establish the

  5. Effects of broadleaf woodland cover on streamwater chemistry and risk assessments of streamwater acidification in acid-sensitive catchments in the UK.

    PubMed

    Gagkas, Z; Heal, K V; Stuart, N; Nisbet, T R

    2008-07-01

    Streamwater was sampled at high flows from 14 catchments with different (0-78%) percentages of broadleaf woodland cover in acid-sensitive areas in the UK to investigate whether woodland cover affects streamwater acidification. Significant positive correlations were found between broadleaf woodland cover and streamwater NO3 and Al concentrations. Streamwater NO3 concentrations exceeded non-marine SO4 in three catchments with broadleaf woodland cover>or=50% indicating that NO3 was the principal excess acidifying ion in the catchments dominated by woodland. Comparison of calculated streamwater critical loads with acid deposition totals showed that 11 of the study catchments were not subject to acidification by acidic deposition. Critical loads were exceeded in three catchments, two of which were due to high NO3 concentrations in drainage from areas with large proportions of broadleaved woodland. The results suggest that the current risk assessment methodology should protect acid-sensitive catchments from potential acidification associated with broadleaf woodland expansion. PMID:18022740

  6. The Serum Metabolite Response to Diet Intervention with Probiotic Acidified Milk in Irritable Bowel Syndrome Patients Is Indistinguishable from that of Non-Probiotic Acidified Milk by 1H NMR-Based Metabonomic Analysis

    PubMed Central

    Pedersen, Simon M. M.; Nielsen, Niels Chr.; Andersen, Henrik J.; Olsson, Johan; Simrén, Magnus; Öhman, Lena; Svensson, Ulla; Malmendal, Anders; Bertram, Hanne C.

    2010-01-01

    The effects of a probiotic acidified milk product on the blood serum metabolite profile of patients suffering from Irritable Bowel Syndrome (IBS) compared to a non-probiotic acidified milk product was investigated using 1H NMR metabonomics. For eight weeks, IBS patients consumed 0.4 L per day of a probiotic fermented milk product or non-probiotic acidified milk. Both diets resulted in elevated levels of blood serum L-lactate and 3-hydroxybutyrate. Our results showed identical effects of acidified milk consumption independent of probiotic addition. A similar result was previously obtained in a questionnaire-based evaluation of symptom relief. A specific probiotic effect is thus absent both in the patient subjective symptom evaluations and at the blood serum metabolite level. However, there was no correspondence between symptom relief and metabolite response on the patient level. PMID:22254002

  7. Diverse coral communities in naturally acidified waters of a Western Pacific reef

    NASA Astrophysics Data System (ADS)

    Shamberger, Kathryn E. F.; Cohen, Anne L.; Golbuu, Yimnang; McCorkle, Daniel C.; Lentz, Steven J.; Barkley, Hannah C.

    2014-01-01

    Anthropogenic carbon dioxide emissions are acidifying the oceans, reducing the concentration of carbonate ions ([CO32-]) that calcifying organisms need to build and cement coral reefs. To date, studies of a handful of naturally acidified reef systems reveal depauperate communities, sometimes with reduced coral cover and calcification rates, consistent with results of laboratory-based studies. Here we report the existence of highly diverse, coral-dominated reef communities under chronically low pH and aragonite saturation state (Ωar). Biological and hydrographic processes change the chemistry of the seawater moving across the barrier reefs and into Palau's Rock Island bays, where levels of acidification approach those projected for the western tropical Pacific open ocean by 2100. Nevertheless, coral diversity, cover, and calcification rates are maintained across this natural acidification gradient. Identifying the combination of biological and environmental factors that enable these communities to persist could provide important insights into the future of coral reefs under anthropogenic acidification.

  8. Remediation of Cr(VI)-Contaminated Soil Using the Acidified Hydrazine Hydrate.

    PubMed

    Ma, Yameng; Li, Fangfang; Jiang, Yuling; Yang, Weihua; Lv, Lv; Xue, Haotian; Wang, Yangyang

    2016-09-01

    Acidified hydrazine hydrate was used to remediate Cr(VI)-contaminated soil. The content of water-soluble Cr(VI) in contaminated soil was 4977.53 mg/kg. The optimal initial pH of hydrazine hydrate solution, soil to solution ratio and molar ratio of Cr(VI) to hydrazine hydrate for remediation of Cr(VI)-contaminated soil were 5.0, 3:1 and 1:3, respectively. Over 99.50 % of water-soluble Cr(VI) in the contaminated soil was reduced at the optimal condition within 30 min. The remediated soil can keep stable within 4 months. Meanwhile the total phosphorus increased from 0.47 to 4.29 g/kg, indicating that using of acidified hydrazine hydrate is an effective method to remediate Cr(VI)-contaminated soil.

  9. Remediation of Cr(VI)-Contaminated Soil Using the Acidified Hydrazine Hydrate.

    PubMed

    Ma, Yameng; Li, Fangfang; Jiang, Yuling; Yang, Weihua; Lv, Lv; Xue, Haotian; Wang, Yangyang

    2016-09-01

    Acidified hydrazine hydrate was used to remediate Cr(VI)-contaminated soil. The content of water-soluble Cr(VI) in contaminated soil was 4977.53 mg/kg. The optimal initial pH of hydrazine hydrate solution, soil to solution ratio and molar ratio of Cr(VI) to hydrazine hydrate for remediation of Cr(VI)-contaminated soil were 5.0, 3:1 and 1:3, respectively. Over 99.50 % of water-soluble Cr(VI) in the contaminated soil was reduced at the optimal condition within 30 min. The remediated soil can keep stable within 4 months. Meanwhile the total phosphorus increased from 0.47 to 4.29 g/kg, indicating that using of acidified hydrazine hydrate is an effective method to remediate Cr(VI)-contaminated soil. PMID:27351195

  10. Catchment and atmospheric effects on acidity of lakes in the northeastern United States

    SciTech Connect

    Davis, R.B.; Anderson, D.S.; Rhodes, T.E.

    1995-06-01

    Sedimentary evidence from 12 lakes in northeastern United States reveals that both catchment and atmospheric processes have caused changes in lake acidity. Diatom remains indicate pH 5.2 to 5.8 (one lake 6.8) for one to two centuries before impacts on the catchment by Euro-americans. These low-alkalinity lakes were very sensitive to altered fluxes of base cations and acids. Several lakes increased in pH by 0.2 to 0.6 unit in the 1800s and early 1900s when their catchments were logged. Re-acidification of some of the lakes was initially due to forest succession. Older sediment from one of the lakes also shows alkalization by natural disturbance, and acidification paralleling forest succession. However, much of the recent acidification, to uniquely low levels by the 1970s is due to high sulfur deposition.

  11. Dissolved phosphorus transport from soil to surface water in catchments with different land use.

    PubMed

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

    2015-03-01

    Diffuse phosphorus (P) export from agricultural land to surface waters is a significant environmental problem. It is critical to determine the natural background P losses from diffuse sources, but their identification and quantification is difficult. In this study, three headwater catchments with differing land use (arable, pasture and forest) were monitored for 3 years to quantify exports of dissolved (<0.45 µm) reactive P and total dissolved P. Mean total P exports from the arable catchment ranged between 0.08 and 0.28 kg ha(-1) year(-1). Compared with the reference condition (forest), arable land and pasture exported up to 11-fold more dissolved P. The contribution of dissolved (<0.45 µm) unreactive P was low to negligible in every catchment. Agricultural practices can exert large pressures on surface waters that are controlled by hydrological factors. Adapting policy to cope with these factors is needed for lowering these pressures in the future. PMID:25681980

  12. A biogeochemical comparison of two well-buffered catchments with contrasting histories of acid deposition

    USGS Publications Warehouse

    Shanley, J.B.; Kram, P.; Hruska, J.; Bullen, T.D.

    2004-01-01

    Much of the biogeochemical cycling research in catchments in the past 25 years has been driven by acid deposition research funding. This research has focused on vulnerable base-poor systems; catchments on alkaline lithologies have received little attention. In regions of high acid loadings, however, even well-buffered catchments are susceptible to forest decline and episodes of low alkalinity in streamwater. As part of a collaboration between the Czech and U.S. Geological Surveys, we compared biogeochemical patterns in two well-studied, well-buffered catchments: Pluhuv Bor in the western Czech Republic, which has received high loading of atmospheric acidity, and Sleepers River Research Watershed in Vermont, U.S.A., where acid loading has been considerably less. Despite differences in lithology, wetness, forest type, and glacial history, the catchments displayed similar patterns of solute concentrations and flow. At both catchments, base cation and alkalinity diluted with increasing flow, whereas nitrate and dissolved organic carbon increased with increasing flow. Sulfate diluted with increasing flow at Sleepers River, while at Pluhuv Bor the sulfate-flow relation shifted from positive to negative as atmospheric sulfur (S) loadings decreased and soil S pools were depleted during the 1990s. At high flow, alkalinity decreased to near 100 ??eq L-1 at Pluhuv Bor compared to 400 ??eq L-1 at Sleepers River. Despite the large amounts of S flushed from Pluhuv Bor soils, these alkalinity declines were caused solely by dilution, which was greater at Pluhuv Bor relative to Sleepers River due to greater contributions from shallow flow paths at high flow. Although the historical high S loading at Pluhuv Bor has caused soil acidification and possible forest damage, it has had little effect on the acid/base status of streamwater in this well-buffered catchment. ?? 2004 Kluwer Academic Publishers.

  13. Inactivation of Salmonella on Sprouting Seeds Using a Spontaneous Carvacrol Nanoemulsion Acidified with Organic Acids.

    PubMed

    Landry, Kyle S; Komaiko, Jennifer; Wong, Dana E; Xu, Ting; McClements, David Julian; McLandsborough, Lynne

    2016-07-01

    Over the past decade, demand has increased for natural, minimally processed produce, including sprout-based products. Sanitization with 20,000 ppm of calcium hypochlorite is currently recommended for all sprouting seeds before germination to limit sprout-related foodborne outbreaks. A potentially promising disinfectant as an alternative to calcium hypochlorite is acidified spontaneous essential oil nanoemulsions. In this study, the efficacy of an acidified carvacrol nanoemulsion was tested against mung beans and broccoli seeds artificially contaminated with a Salmonella enterica Enteritidis cocktail (ATCC BAA-709, ATCC BAA-711, and ATCC BAA-1045). Treatments were performed by soaking inoculated seeds in acidified (50 mM acetic or levulinic acid) carvacrol nanoemulsions (4,000 or 8,000 ppm) for 30 or 60 min. After treatment, the number of surviving cells was determined via plate counts and/or the most probable number (MPN) approach. Treatment for 30 min successfully reduced Salmonella Enteritidis by 4 log CFU/g on mung beans (from an initial contamination level of 4.2 to 4.6 log CFU/g) and by 2 log CFU/g on broccoli seeds (from an initial contamination level of 2.4 to 2.6 log CFU/g) to below our detection limit (≤3 MPN/g). Treated seeds were sprouted and tested for the presence of pathogens and sprout yield. The final sprout product had no detectable pathogens, and total sprout yield was not influenced by any treatment.

  14. Determination of 5-log pathogen reduction times for heat-processed, acidified vegetable brines.

    PubMed

    Breidt, F; Hayes, J S; Osborne, J A; McFeeters, R F

    2005-02-01

    Recent outbreaks of acid-resistant food pathogens in acid foods, including apple cider and orange juice, have raised concerns about the safety of acidified vegetable products. We determined pasteurization times and temperatures needed to assure a 5-log reduction in the numbers of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella strains in acidified cucumber pickle brines. Cocktails of five strains of each pathogen were (separately) used for heat-inactivation studies between 50 and 60 degrees C in brines that had an equilibrated pH value of 4.1. Salmonella strains were found to be less heat resistant than E. coli O157:H7 or L. monocytogenes strains. The nonlinear killing curves generated during these studies were modeled using a Weibull function. We found no significant difference in the heat-killing data for E. coli O157:H7 and L. monocytogenes (P = 0.9709). The predicted 5-log reduction times for E. coli O157:H7 and L. monocytogenes were found to fit an exponential decay function. These data were used to estimate minimum pasteurization times and temperatures needed to ensure safe processing of acidified pickle products and show that current industry pasteurization practices offer a significant margin of safety.

  15. Long-term changes of acidifying deposition in Finland (1973-2000).

    PubMed

    Vuorenmaa, Jussi

    2004-01-01

    The long-term changes of acidifying deposition in Finland during the period 1973-2000 were studied using bulk deposition data from 19 stations belonging to the national monitoring network. The regional-scale approach (southern, central and northern Finland) was used for trend assessment with respect to implementation of European sulphur (S) emission reduction amendments involving deposition changes prior to (1973-1985) and after (1986-2000) the agreements (S protocols in 1985 and 1994). There were no marked changes in sulphate deposition between the 1970s and 1980s and consistent trends in 1973-1985 were not observed. Deposition of nitrogen (N) compounds, particularly NO3-N, were increasing between the 1970s and 1980s. Deposition of base cations exhibited a slight decline throughout the 1970s and 1980s. Decrease of calcium and magnesium deposition without corresponding decrease in sulphate resulted in increased acidifying potential (AP) of deposition. Due to successful implementation of S (and N) emission reduction measures, sulphate deposition has decreased substantially (30% in northern and up to 60% in southern Finland) since the late 1980s. N deposition also decreased, but less than S deposition. Base cation deposition has also declined substantially, but this decline appeared to be leveling off during the 1990s, accounting for the decrease of AP in deposition. The observed deposition pattern is in agreement with the on-going biochemical recovery of acidified small Finnish lakes taking place since the early 1990s.

  16. Inactivation of Salmonella on Sprouting Seeds Using a Spontaneous Carvacrol Nanoemulsion Acidified with Organic Acids.

    PubMed

    Landry, Kyle S; Komaiko, Jennifer; Wong, Dana E; Xu, Ting; McClements, David Julian; McLandsborough, Lynne

    2016-07-01

    Over the past decade, demand has increased for natural, minimally processed produce, including sprout-based products. Sanitization with 20,000 ppm of calcium hypochlorite is currently recommended for all sprouting seeds before germination to limit sprout-related foodborne outbreaks. A potentially promising disinfectant as an alternative to calcium hypochlorite is acidified spontaneous essential oil nanoemulsions. In this study, the efficacy of an acidified carvacrol nanoemulsion was tested against mung beans and broccoli seeds artificially contaminated with a Salmonella enterica Enteritidis cocktail (ATCC BAA-709, ATCC BAA-711, and ATCC BAA-1045). Treatments were performed by soaking inoculated seeds in acidified (50 mM acetic or levulinic acid) carvacrol nanoemulsions (4,000 or 8,000 ppm) for 30 or 60 min. After treatment, the number of surviving cells was determined via plate counts and/or the most probable number (MPN) approach. Treatment for 30 min successfully reduced Salmonella Enteritidis by 4 log CFU/g on mung beans (from an initial contamination level of 4.2 to 4.6 log CFU/g) and by 2 log CFU/g on broccoli seeds (from an initial contamination level of 2.4 to 2.6 log CFU/g) to below our detection limit (≤3 MPN/g). Treated seeds were sprouted and tested for the presence of pathogens and sprout yield. The final sprout product had no detectable pathogens, and total sprout yield was not influenced by any treatment. PMID:27357030

  17. Stormflow generation: a meta-analysis of field studies and research catchments

    NASA Astrophysics Data System (ADS)

    Barthold, Frauke; Elsenbeer, Helmut

    2014-05-01

    Runoff characteristics are expressions of runoff generation mechanisms. In this study, we want to test the hypothesis if storm hydrographs of catchments with prevailing near-surface flow paths are dominated by new water. We aim to test this hypothesis using published data from the scientific literature. We developed a classification system based on three runoff characteristics: (1) hydrograph response (HR: slowly or quickly), (2) the temporal source of water that dominates the hydrograph (TS: pre-event vs. event water) and (3) the flow paths that the water takes until it is released to the stream (FP: subsurface vs. surface flow paths). We then performed a literature survey to collect information on these runoff characteristics for small, forested headwater catchments that served as study areas in runoff generation studies and assigned each study catchment to one of the 8 classes. For this purpose, we designed a procedure to objectively diagnose the predominant conceptual model of storm flow generation in each catchment and assess its temporal and spatial relevance for the catchment. Finally, we performed an explorative analysis of the classified research catchments and summarized field evidence. Our literature survey yielded a sample of 22 research catchments that fell within our defined criteria (small, naturally forested catchments which served as study areas in stormflow generation studies). We applied our classification procedure to all of these catchments. Among them were 14 catchments for which our meta-analysis yielded a complete set of stormflow characteristics resulting in one of the 8 model concepts and were assigned into our classification scheme. Of the 14 classified research catchments, 10 were dominated by subsurface flow paths while 4 were dominated by overland flow. The data also indicate that the spatial and temporal relevance is high for catchments with subsurface flow paths while often weak for surface flow paths dominated catchments. The

  18. Dynamically Evolving Models for Dynamic Catchments: Application of the Locally Linear Dual EnKF to a Catchment with Land Use Change

    NASA Astrophysics Data System (ADS)

    Pathiraja, S. D.; Marshall, L. A.; Sharma, A.; Moradkhani, H.

    2015-12-01

    Catchments are dynamic, constantly undergoing change be it naturally or due to anthropogenic influences. Changes in land surface conditions such as disturbance due to bushfire or erosion, urbanisation, deforestation or afforestation will affect a catchment's hydrologic regime. Models calibrated to pre-change conditions will lead to biased streamflow predictions, unless the change is explicitly accounted for in the model. A modelling methodology that is capable of adjusting its form (for instance, through time varying parameters) as catchments undergo change is therefore needed. We developed a framework for automatically and objectively detecting time variations in model parameters using Data Assimilation. The so called Locally Linear Dual EnKF was previously tested against a range of synthetic case studies and shown to reproduce known temporal variations from assimilating streamflow observations only. In this study, we apply the Locally Linear Dual EnKF to the Wights and Salmon paired catchments in Western Australia. Both were initially forested and monitored for a 3 year period, after which Wights was fully cleared whilst Salmon remained unchanged. The lumped conceptual hydrologic model (PDM) was calibrated over the stationary period and the optimal parameterisation used to initialise the Locally Linear Dual EnKF. Resultant parameter trajectories for the Salmon catchment were relatively stationary, whilst parameters for the Wights catchment were automatically adjusted to produce greater flood peaks, sooner after rainfall, consistent with observations. A significant improvement in both streamflow prediction and catchment soil moisture was obtained with the Locally Linear Dual EnKF, compared to the time invariant parameter case. This application has demonstrated the usefulness of this framework for improving predictions in rapidly changing catchments.

  19. Modeling of matters removal from swampy catchment

    NASA Astrophysics Data System (ADS)

    Inishev, N. G.; Inisheva, L. I.

    2010-05-01

    the estimations were made taking into account layering unevenness of snow cover in deferent landscapes. Stored water distribution in the limits of every landscape was approximated by the curve of gamma distribution with parameters which are the results of snow survey. Everyday basin water yield was determined as difference between excesses of water coming above usage for filling of its water retaining tank. The size of the water retaining tank before start of snow melting depends on the basin wetting in the previous autumn. Autumn river flow is taken as a degree of water retaining tank filling before the snow melt. It is supposed that there is a process of water accumulation at slopes. Between theses water supplies and overland runoffs there is a nonlinear link. Temporary melt water detention, which comes from mire in swamp forest, is considered. Estimations are made individually for field, forest and swamp parts of the basin of the river Kljuch. Estimation of HA removal from the surface of catchment of the river Kljuch is taken as an example of model application. The results reveal possibilities of the given approach to modeling of dissolved matters removal from the swampy area. Acknowledgements: This research was supported by RFFR (No.No. 09-05-00235, 09-05-99007), Minister of education and science (No. 02.740.11.0325).

  20. Hydrologic connectivity between landscapes and streams: Transferring reach- and plot-scale understanding to the catchment scale

    USGS Publications Warehouse

    Jencso, K.G.; McGlynn, B.L.; Gooseff, M.N.; Wondzell, S.M.; Bencala, K.E.; Marshall, L.A.

    2009-01-01

    The relationship between catchment structure and runoff characteristics is poorly understood. In steep headwater catchments with shallow soils the accumulation of hillslope area (upslope accumulated area (UAA)) is a hypothesized first-order control on the distribution of soil water and groundwater. Hillslope-riparian water table connectivity represents the linkage between the dominant catchment landscape elements (hillslopes and riparian zones) and the channel network. Hydrologic connectivity between hillslope-riparian-stream (HRS) landscape elements is heterogeneous in space and often temporally transient. We sought to test the relationship between UAA and the existence and longevity of HRS shallow groundwater connectivity. We quantified water table connectivity based on 84 recording wells distributed across 24 HRS transects within the Tenderfoot Creek Experimental Forest (U.S. Forest Service), northern Rocky Mountains, Montana. Correlations were observed between the longevity of HRS water table connectivity and the size of each transect's UAA (r2 = 0.91). We applied this relationship to the entire stream network to quantify landscape-scale connectivity through time and ascertain its relationship to catchment-scale runoff dynamics. We found that the shape of the estimated annual landscape connectivity duration curve was highly related to the catchment flow duration curve (r2 = 0.95). This research suggests internal catchment landscape structure (topography and topology) as a first-order control on runoff source area and whole catchment response characteristics. Copyright 2009 by the American Geophysical Union.

  1. A water and sediment budget for a Mediterranean mountainous catchment (Southern Pyrenees)

    NASA Astrophysics Data System (ADS)

    Tuset, Jordi; Vericat, Damià; Batalla, Ramon J.

    2016-04-01

    Sediment transport in Mediterranean mountainous catchments is highly variable influenced principally by sediment availability, which in turn is controlled by the temporal and spatial variability of rainfall, runoff and land uses. In this paper we present the water and sediment budget of the Ribera Salada, a Mediterranean forest catchment located in the Catalan Pre-Pyrenees (NE Iberian Peninsula). The river drains an area of 224 km2. The data acquisition design is composed by five nested experimental sub-catchments. Each monitoring station registers discharge and suspended sediment transport continuously. Here we present the data obtained between 2012 and 2013, two contrasted hydrological years. These data allows to analyse the contribution of each sub-catchment to the total water and suspended sediment yield of the catchment at multiple temporal scales. Annual water yield in the catchment outlet varied between 15 and 31 hm3 y-1. Maximum peak flow in the outlet of the basin was 60.9 m3 s-1; equivalent to a specific discharge of 0.28 m3 s-1 km2. Results indicate that, hydrologically, the catchment can divided in two areas with contrasted regimes. The upper part of catchment is the wettest zone, where the water yield of each sub-catchment is in directly and positive correlated to its area. In contrast, the bottom of the valley has an ephemeral hydrological regime that only supplies water during important rainfall events. Annual suspended sediment load at the catchment outlet oscillated between 615 and 3415 t y-1, with an average value of 2015 t y-1 (i.e. 9.3 t km‑2 y‑1). In contrast to the water yield, most of the suspended sediment load (i.e. 80%) is supplied from the driest part of the catchment where sediment availability is greater and there is a greater connectivity between sediment sources and the channel network. The humid part of the catchment only yielded the 20% of the sediment load, where, as in the case of the water yield, sediment yield is directly

  2. Sediment budget for Rediu reservoir catchment, North-Eastern Romania

    NASA Astrophysics Data System (ADS)

    Todosi, Cristian; Niculita, Mihai

    2016-04-01

    Sediment budgets are a useful tool for geomorphologic analysis, catchment management and environmental assessment, despite the uncertainties related to their assessment. We present the sediment budget construction and validation for a small catchment of 9.5319 kmp (953.19 ha) situated in the North-Eastern part of Romania. The Rediu reservoir was built between 1986 and 1988, on Rediu valley, a left tributary of Bahlui river, north-west from Iasi city. The catchment of the reservoir has 6.5 km in length and 2.5 km in maximum width, the altitudes decreasing from 170 m in the northern part, to 52 m in the southern part. The valley is symmetric, the altitude of the hillslopes going between 200 m to 75 m in one km length, in the transversal section with the maximum width. The floodplain is narrow having between 20 m to 210 m (in the area of confluence with Breazu tributary). The mean slope of the catchment is 6.4 degree, the maximum slope being 24.6 degrees. The length of channels which show banks of up to 2 m is 19.98 km. The land is used predominantly as crops (58.1 %), 16.7 % being covered by pastures (from which over half are eroded), 11.5 % percent of the catchment being covered by planted forests, 9.2 % by rural constructions and roads, 2.9 % by hayfields, 1.5 % by lakes and 0.1 % by orchards. Beside the Rediu reservoir, there are three ponds (15 771, 1761 and 751 sqm) in the catchment. We considered the trap efficiency for the reservoir and the ponds to be 95%. Aerial images from 1963, 1978 , 1984, 2005, 2008, 2010, 2012 and 2014 were used to assess the state of geomorphological processes before and after the reservoir construction. After 1970 a gully system situated in Breazu tributary sub-catchment and several active landslides along the main valley left side were forested. Beside these processes, soil erosion and human impact by constructions are the main processes generating sediment in the study area. The sediment yields were quantified by estimating the

  3. Dioxins, PCBs, and HCB in soil and peat profiles from a pristine boreal catchment.

    PubMed

    Bergknut, Magnus; Laudon, Hjalmar; Wiberg, Karin

    2010-07-01

    The aim of this study was to explore how atmospherically derived soil pollution is affected by environmental processes at two typical boreal catchment landscape type settings: wetlands and forested areas. Measurements of hydrophobic organic compounds (HOCs) in forest soil and peat from an oligotrophic mire at various depths were performed at a remote boreal catchment in northern Sweden. HOCs in peat were evenly distributed throughout the body of the mire while levels of HOCs in the forest soil increased with increased amount of organic matter. Evaluation of HOC composition by principal component analysis (PCA) showed distinct differences between surface soils and deeper soil and peat samples. This was attributed to vertical transport, degradation and/or shifting sources over time. The calculated net vertical transport differed between surface layers (0.3%) and deeper soils (8.0%), suggesting that vertical transport conditions and processes differ in the deeper layers compared to the surface layers.

  4. Total organic carbon in streamwater from four long-term monitored catchments in Norway

    SciTech Connect

    Lydersen, E.; Henriksen, A. )

    1994-01-01

    Flux, concentration, and net charge of total organic carbon (TOC) have been related to different physico-chemical parameters present in air/precipitation and streamwater at four long-term monitored catchments in Norway, during the period 1986-1992. The catchments vary a lot with respect to annual water input, acid rain, and the streamwater concentration of TOC. Thus, relationships between concentration/NC of TOC and chemical compounds in precipitation and streamwater were often catchment-specific. However, seasonal climatic changes, like air temperature and hydrology, were found to be important for the concentration variations of TOC. Organic matter has an important role in weathering reactions in the catchment. The correlation between concentration of total aluminum (RAL) and SO[sub 4][sup *] was far more significant (r=0.93) compared with the corresponding correlations between RAL and TOC (r=0.40). The NC of TOC was found to be most affected by compounds in precipitation, primarily the inputs of sea salts. In the most acidified areas, the influence from strong acid inputs also affects the NC of TOC, but less significantly. Variations in sea salt inputs (primarily NaCl) are more important for the temporary variation in NC of TOC compared with H[sup +] ions at these sites. At a certain TOC level, the weak organic acids may affect the streamwater pH. A comparison between measured and calculated concentrations of organic Al indicated that the dissociation constants (pK-values) of the organic acids present at Birkenes must be higher and/or the Al-complexing constants lower compared with the constants given by the programme. 55 refs., 10 figs., 8 tabs.

  5. Partitioning and bioavailability of mercury in an experimentally acidified Wisconsin lake

    USGS Publications Warehouse

    Wiener, James G.; Fitzgerald, William F.; Watras, Carl J.; Rada, Ronald G.

    1990-01-01

    We studied the partitioning of mercury (Hg) among air, water, sediments and fish at Little Rock Lake, a clear water seepage lake in north-central Wisconsin. The lake was divided with a sea curtain into two basins, one acidified with sulfuric acid to pH 5.6 for two years and the other an untreated reference site (mean pH 6.1), to document the effects of acidification. Trace-metal-free protocols were used to measure Hg at the picomolar level in air and water. Total gaseous Hg in air samples averaged 2.0 ng/m3. Total Hg in unfiltered water samples collected in 1986 after the fall overturn averaged about 1 ng/L in the acidified and reference basins. Mercury in surficial sediments was strongly correlated with volatile matter content and ranged from 10 to about 170 ng/g (dry weight) in both basins. Total Hg concentrations in whole, calendar age-1 yellow perch (Perca flavescens), sampled after one year of residence in the lake, averaged 114 ng/g (fresh weight) in the reference basin and 135 ng/g in the acidified basin – a highly significant (p < 0.01) difference. The mean whole-body burden (quantity) of Hg in age-1 perch did not differ between basins after the first year, but was significantly greater in the treatment basin than in the reference basin after the second year of acidification. Differences between the two basins in the bioaccumulation of Hg were attributed to internal (within-lake) processes that influence the bioavailability of the metal. An initial Hg budget for the treatment basin of Little Rock Lake showed that atmospheric deposition and sedimentary remobilization of Hg are potentially important processes influencing its biogeochemical cycling and uptake by fish.

  6. What causes similarity in catchments?

    NASA Astrophysics Data System (ADS)

    Savenije, Hubert

    2014-05-01

    One of the biggest issues in hydrology is how to handle the heterogeneity of catchment properties at different scales. But is this really such a big issue? Is this problem not merely the consequence of how we conceptualise and how we model catchments? Is there not far more similarity than we observe. Maybe we are not looking at the right things or at the right scale to see the similarity. The identity of catchments is largely determined by: the landscape, the ecosystem living on the landscape, and the geology, in that order. Soils, which are often seen as a crucial aspect of hydrological behaviour, are far less important, as will be demonstrated. The main determinants of hydrological behaviour are: the landscape composition, the rooting depth and the phenology. These determinants are a consequence of landscape and ecosystem evolution, which, in turn, are the manifestations of entropy production. There are striking similarities between catchments. The different runoff processes from hillslopes are linked and similar in different environments (McDonnell, 2013). Wetlands behave similarly all over the world. The key is to classify landscapes and to link the ecosystems living on them to climate. The ecosystem then is the main controller of hydrological behaviour. Besides phenology, the rooting depth is key in determining runoff behaviour. Both are strongly linked to climate and much less to soil properties. An example is given of how rooting depth is determined by climate, and how rooting depth can be predicted without calibration, providing a strong constraints on the prediction of rainfall partitioning and catchment runoff.

  7. Metal accumulation and metallothionein concentrations in tree swallow nestlings near acidified lakes

    SciTech Connect

    St. Louis, V.; Breebaart, L. . Dept. of Zoology); Barlow, J.C. . Dept. of Zoology Royal Ontario Museum, Toronto, Ontario . Dept. of Ornithology); Klaverkamp, J.F. . Dept. of Fisheries and Oceans)

    1993-07-01

    The authors studied metal accumulation in hepatic and renal tissues of tree swallow (Tachycineta bicolor) nestlings at acidified and nonacid reference lakes in northwestern Ontario. Hepatic concentrations of metallothionein (metal-binding proteins, MT) in tree swallow nestlings were negatively correlated with pH of the nest-site lake. Combined concentrations of Cu and Zn in the liver were correlated with liver MT concentrations, but Cd was not. Although no overt signs of metal toxicity were observed in nestlings near acid lakes, the results clearly provided evidence that metals are transferred from acid lakes to birds and that these metals are correlated with increases in hepatic MT production.

  8. The effect of sucrose on unfrozen water and syneresis of acidified sodium caseinate-xanthan gels.

    PubMed

    Braga, A L M; Cunha, R L

    2005-07-01

    The influence of the ingredients of acidified Na caseinate-xanthan-sucrose gels on thermophysical properties and syneresis of the gels was studied. Sucrose concentration affected all of the gel equilibrium properties and the rate of syneresis. The positive effect of sucrose on syneresis and unfrozen water (UFW) values was attributed to different effects. The amount of UFW was governed mainly by the colligative properties of sucrose whereas the equilibrium syneresis behaviour was associated with the changes in network dynamics caused by the kosmotropic properties of sucrose. The latter could enhance xanthan-sucrose association or favour xanthan-protein interactions.

  9. Landscape heterogeneity drives contrasting concentration-discharge relationships in shale headwater catchments

    NASA Astrophysics Data System (ADS)

    Herndon, E. M.; Dere, A. L.; Sullivan, P. L.; Norris, D.; Reynolds, B.; Brantley, S. L.

    2015-08-01

    Solute concentrations in stream water vary with discharge in patterns that record complex feedbacks between hydrologic and biogeochemical processes. In a comparison of three shale-underlain headwater catchments located in Pennsylvania, USA (the forested Shale Hills Critical Zone Observatory), and Wales, UK (the peatland-dominated Upper Hafren and forest-dominated Upper Hore catchments in the Plynlimon forest), dissimilar concentration-discharge (C-Q) behaviors are best explained by contrasting landscape distributions of soil solution chemistry - especially dissolved organic carbon (DOC) - that have been established by patterns of vegetation and soil organic matter (SOM). Specifically, elements that are concentrated in organic-rich soils due to biotic cycling (Mn, Ca, K) or that form strong complexes with DOC (Fe, Al) are spatially heterogeneous in pore waters because organic matter is heterogeneously distributed across the catchments. These solutes exhibit non-chemostatic behavior in the streams, and solute concentrations either decrease (Shale Hills) or increase (Plynlimon) with increasing discharge. In contrast, solutes that are concentrated in soil minerals and form only weak complexes with DOC (Na, Mg, Si) are spatially homogeneous in pore waters across each catchment. These solutes are chemostatic in that their stream concentrations vary little with stream discharge, likely because these solutes are released quickly from exchange sites in the soils during rainfall events. Furthermore, concentration-discharge relationships of non-chemostatic solutes changed following tree harvest in the Upper Hore catchment in Plynlimon, while no changes were observed for chemostatic solutes, underscoring the role of vegetation in regulating the concentrations of certain elements in the stream. These results indicate that differences in the hydrologic connectivity of organic-rich soils to the stream drive differences in concentration behavior between catchments. As such, in

  10. Coevolution of volcanic catchments in Japan

    NASA Astrophysics Data System (ADS)

    Yoshida, Takeo; Troch, Peter A.

    2016-03-01

    Present-day landscapes have evolved over time through interactions between the prevailing climates and geological settings. Understanding the linkage between spatial patterns of landforms, soils, and vegetation in landscapes and their hydrological response is critical to make quantitative predictions in ungaged basins. Catchment coevolution is a theoretical framework that seeks to formulate hypotheses about the mechanisms and conditions that determine the historical development of catchments and how such evolution affects their hydrological response. In this study, we selected 14 volcanic catchments of different ages (from 0.225 to 82.2 Ma) in Japan. We derived indices of landscape properties (drainage density and slope-area relationship) as well as hydrological response (annual water balance, baseflow index, and flow-duration curves) and examined their relation with catchment age and climate (through the aridity index). We found a significant correlation between drainage density and baseflow index with age, but not with climate. The intra-annual flow variability was also significantly related to catchments age. Younger catchments tended to have lower peak flows and higher low flows, while older catchments exhibited more flashy runoff. The decrease in baseflow with catchment age is consistent with the existing hypothesis that in volcanic landscapes the major flow pathways change over time from deep groundwater flow to shallow subsurface flow. The drainage density of our catchments decreased with age, contrary to previous findings in a set of similar, but younger volcanic catchments in the Oregon Cascades, in which drainage density increased with age. In that case, older catchments were thought to show more landscape incision due to increasing near-surface lateral flow paths. Our results suggests two competing hypotheses on the evolution of drainage density in mature catchments. One is that as catchments continue to age, the hydrologically active channels retreat

  11. Unraveling soil moisture responses to storms and relationships to runoff in a headwater catchment

    NASA Astrophysics Data System (ADS)

    Singh, N.

    2015-12-01

    Soil moisture exhibits complex spatiotemporal patterns, both laterally across landscapes and vertically within soil profiles. These patterns of soil moisture can have strong influences on runoff generation, especially in catchments having large capacities for soil water storage and transmission. The body of literature on runoff generation is expansive, yet we still have a great deal to learn about how the spatial and temporal heterogeneity of soil moisture influences catchment-scale hydrologic responses to storm events. With this in mind, we investigated soil moisture responses to storm events across several landscape positions in a steep, forested headwater catchment. We measured volumetric water content (VWC) continuously for two years at 45 points representing different combinations of landscape position and soil depth within a 13 ha catchment at Coweeta Hydrologic Laboratory in the Southern Appalachian Mountains. We also monitored shallow groundwater levels at six locations within the catchment along with runoff at the catchment outlet. To investigate soil moisture response during events, we assessed absolute change in magnitude of VWC (Δs) and lag time (Δt) between peak VWC and peak precipitation for 39 events during the two-year study period. Our results showed that storm depth and antecedent moisture explained some of the spatiotemporal patterns of Δs; however, the explanatory power varied with the hillslope and season. Furthermore, we did not detect topographic control of Δs or Δt at most of the locations monitored. By evaluating the sequence of Δt, groundwater response, and runoff response for each storm, we characterized the hydrologic behavior of the study hillslopes for the 39 storm events.The characterization of hydrologic behavior reveals interrelationships between soil moisture and shallow groundwater, and their combined influence on runoff at the catchment outlet. This work provides new insights on links between the spatiotemporal variability

  12. Modeling nonlinear responses of DOC transport in boreal catchments in Sweden

    NASA Astrophysics Data System (ADS)

    Kasurinen, Ville; Alfredsen, Knut; Ojala, Anne; Pumpanen, Jukka; Weyhenmeyer, Gesa A.; Futter, Martyn N.; Laudon, Hjalmar; Berninger, Frank

    2016-07-01

    Stream water dissolved organic carbon (DOC) concentrations display high spatial and temporal variation in boreal catchments. Understanding and predicting these patterns is a challenge with great implications for water quality projections and carbon balance estimates. Although several biogeochemical models have been used to estimate stream water DOC dynamics, model biases common during both rain and snow melt-driven events. The parsimonious DOC-model, K-DOC, with 10 calibrated parameters, uses a nonlinear discharge and catchment water storage relationship including soil temperature dependencies of DOC release and consumption. K-DOC was used to estimate the stream water DOC concentrations over 5 years for eighteen nested boreal catchments having total area of 68 km2 (varying from 0.04 to 67.9 km2). The model successfully simulated DOC concentrations during base flow conditions, as well as, hydrological events in catchments dominated by organic and mineral soils reaching NSEs from 0.46 to 0.76. Our semimechanistic model was parsimonious enough to have all parameters estimated using statistical methods. We did not find any clear differences between forest and mire-dominated catchments that could be explained by soil type or tree species composition. However, parameters controlling slow release and consumption of DOC from soil water behaved differently for small headwater catchments (less than 2 km2) than for those that integrate larger areas of different ecosystem types (10-68 km2). Our results emphasize that it is important to account for nonlinear dependencies of both, soil temperature, and catchment water storage, when simulating DOC dynamics of boreal catchments.

  13. Nitrogen loadings and environmental impacts in rice agriculture catchments in subtropical central China

    NASA Astrophysics Data System (ADS)

    Wang, Y.

    2015-12-01

    The severe deterioration of water quality in rice agriculture catchments challenges ecologists and hydrologists in exploring how rice agriculture affects nutrient loadings and water quality. This research observed the nitrogen (N) concentrations in stream water and groundwater in one forest and five rice agriculture catchments in subtropical central China to quantify the relationships between rice agriculture intensification, water quality of water bodies, and catchment N loadings. Our results indicate that intensive rice agriculture deteriorated stream water quality. A non-linear fitting analysis using a Boltzmann sigmoid function suggests that the concentrations and mass fluxes of ammonium-N (NH4+-N), nitrate-N (NO3--N), and total N (TN) in stream water increase with the areal proportion of rice agriculture in the catchments; however, these increases can only be detected when the areal proportions of rice agriculture in the catchments are greater than 13-30%, highlighting the importance of reasonable land use planning for managing stream water quality as well as N loadings from catchments. The factorial correspondence analysis (FCA) also suggests that rice agriculture has a potential to impose groundwater NH4+-N pollution, particularly in the soil exhausting season of July - October. And, the great N fertilizer application rates for rice cropping can increase the groundwater NO3-N and TN concentrations due to large quantities of N leaching into groundwater system beneath the paddy fields. The high N concentrations in groundwater result in strong N loadings via the base flow process. The NO3--N loadings via the base flow reaches 0.12-0.27 kg N ha-1 month-1 in the rice agriculture catchments, contributing 27.3%-36.5% of the total NO3--N loadings by the stream discharge. Therefore, the best management practices for N reduction and the smart land use planning should be applied in the rice agriculture catchments to improve water quality and mitigate N loadings.

  14. Rheological and structural properties of differently acidified and renneted milk gels.

    PubMed

    Liu, X T; Zhang, H; Wang, F; Luo, J; Guo, H Y; Ren, F Z

    2014-01-01

    In this study we assessed the rheological and structural properties of differently acidified and renneted milk gels by controlling pH value and renneting extent. Skim milk were exactly renneted to 4 extents (20, 35, 55, and 74%) and then direct acidified to the desired pH (4.8, 5.0, 5.2, 5.5, 5.8, and 6.2), respectively. Rheological properties were assessed by dynamic rheological measurements, structural properties were studied by spontaneous whey separation and confocal laser scanning micrograph, and protein interactions were studied by dissociation test. Results showed that minimally renneted milk samples (20 and 35%) formed weak gels with low storage modulus, and the acidification range within which gels could form was narrow (pH ≤ 5.2). Highly renneted milk samples formed more gels with high storage modulus. The results of this study revealed that acidification determined the structural properties of highly renneted milk gels. As pH increased from 5.0 to 6.2, highly renneted milk gels had lower loss tangent, decreased spontaneous syneresis, and smaller pores. For both the low and high rennetings, divalent calcium bonds contributed less at low pH than at high pH. In conclusion, renneting increased the pH range suitable for gel formation; acidification determined the spontaneous syneresis and microstructure of highly renneted milk gels.

  15. Protozoan grazing on bacteria at the sediment-water interface of an acidified lake

    SciTech Connect

    Tremaine, S.C.

    1988-01-01

    Protozoan grazing on bacteria has been hypothesized to link the detrital and grazer food chains in aquatic ecosystems. The current study of protozoan bacterivory, evaluated methods, quantified bacterivory, and evaluated the role of protozoa at the sediment-water interface of an acidified lake ecosystem, Lake Anna, Virginia. Three limnetic methods for determining protozoan bacterivory were tested for applicability at the sediment-water interface. The eucaryote inhibitor, cycloheximide, was found unsatisfactory because it did not uniformly inhibit growth of target eucaryotes, and because it inhibited non-target anaerobic procaryotes. The filtration method was found to have limited application in sediment systems due to filtrational loss of particle-associated bacteria. The dilution method was tested for violations of its critical assumptions: bacterial growth is exponential; grazing mortality is proportional to the dilution factor; and bacterial growth rates are unaltered under experimental conditions. These assumptions were found not to be violated, and this method was used in subsequent grazing experiments. Carbon loading to the acidified arm of Lake Anna was 41 {times} 10{sup 6} g C {times} y{sup {minus}1}. This appears to be adequate carbon loading to support bacterial production and, in turn, protozoan bacterivory and production. Though there is no direct evidence that zooplankton graze on protozoa in this system, however, there is sufficient protozoan production to support an additional trophic level.

  16. Resilience of epilithic algal assemblages in atmospherically and experimentally acidified boreal lakes.

    PubMed

    Vinebrooke, Rolf D; Graham, Mark D; Findlay, David L; Turner, Michael A

    2003-04-01

    Algal assemblages can be highly responsive to environmental changes in recovering acidified lakes. We compared epilithic algal assemblages in boreal lakes during chemical recovery from atmospheric (Killarney Park, Ontario) and experimental (Lake 302S, Experimental Lakes Area, Ontario) acidification to assess the impact of spatial and temporal scale of severe acidification on taxonomic resilience (i.e. recovery rate). Resilience was measured as the distance traveled by lakes in ordination space during pH recovery based on canonical correspondence analysis. Resilience was relatively negligible in the Killarney lakes, suggesting that eight years of experimental acidification in Lake 302S had less impact on biological recovery than did decades of regional acidification. Increases in dissolved organic carbon, dissolved inorganic carbon, and calcium best explained temporal variance of epilithic species abundances in the recovering acidified lakes. In Lake 302S, contrasting trajectories of taxonomic resilience and resistance, i.e. displacement from reference conditions following a perturbation, indicated that ecological factors affecting epilithon differed at corresponding pH levels during recovery and acidification. Our findings reveal that modeling of ecosystem recovery from severe acidification must account for the spatial and temporal scale of the perturbation, and biological delay responses that result in differences between recovery and acidification trajectories.

  17. Anaerobic digestion of sulfate-acidified cattle slurry: One-stage vs. two-stage.

    PubMed

    Moset, Veronica; Ottosen, Lars Ditlev Mørck; Xavier, Cristiane de Almeida Neves; Møller, Henrik Bjarne

    2016-05-15

    Two strategies to include acidified cattle manure (AcCM) in co-digestion with normal cattle manure (CM) are presented in this work. The strategies are a single thermophilic (50 °C) continuous stirred tank reactor (CSTR) anaerobic digestion and a two-step (65 °C + 50 °C) CSTR process. In both strategies, two different inclusion levels of H2SO4-acidified CM (10% and 20%) in co-digestion with normal CM were tested and compared with a control CSTR fed only CM. Important enhancement of methane (CH4) yield and solid reductions were observed in the thermophilic one-step CSTR working with 10% AcCM. However, a higher inclusion level of AcCM (20%) caused volatile fatty acid accumulation in the reactor and a more than 30% reduction in CH4 production. In terms of CH4 production, when 10% of AcCM was co-digested with 90% of CM, the two-step anaerobic co-digestion yielded less than the single step. During the first step of the two-step CSTR process, acidogenesis and a partial sulfate reduction were achieved. However, sulfide stripping between the first and the second step must be promoted in order to advance this technology.

  18. Spatial community shift from hard to soft corals in acidified water

    NASA Astrophysics Data System (ADS)

    Inoue, Shihori; Kayanne, Hajime; Yamamoto, Shoji; Kurihara, Haruko

    2013-07-01

    Anthropogenic increases in the partial pressure of CO2 (pCO2) cause ocean acidification, declining calcium carbonate saturation states, reduced coral reef calcification and changes in the compositions of marine communities. Most projected community changes due to ocean acidification describe transitions from hard coral to non-calcifying macroalgal communities; other organisms have received less attention, despite the biotic diversity of coral reef communities. We show that the spatial distributions of both hard and soft coral communities in volcanically acidified, semi-enclosed waters off Iwotorishima Island, Japan, are related to pCO2 levels. Hard corals are restricted to non-acidified low- pCO2 (225μatm) zones, dense populations of the soft coral Sarcophyton elegans dominate medium- pCO2 (831μatm) zones, and both hard and soft corals are absent from the highest- pCO2 (1,465μatm) zone. In CO2-enriched culture experiments, high- pCO2 conditions benefited Sarcophyton elegans by enhancing photosynthesis rates and did not affect light calcification, but dark decalcification (negative net calcification) increased with increasing pCO2. These results suggest that reef communities may shift from reef-building hard corals to non-reef-building soft corals under pCO2 levels (550-970μatm) predicted by the end of this century, and that higher pCO2 levels would challenge the survival of some reef organisms.

  19. Growth and physiological condition of black ducks reared on acidified wetlands

    USGS Publications Warehouse

    Rattner, B.A.; Haramis, G.M.; Chu, D.S.; Bunck, C.M.; Scanes, C.G.

    1987-01-01

    Acid deposition has been identified as one of several possible factors contributing to the decline of some waterfowl populations in North America. In an effort to examine the effects of acidification on black duck (Anas rubripes) recruitment, growth and physiological condition were monitored in ducklings foraging for a 10-day trial (days 10-20 of life) on acidified (pH 5.0) and : circumneutral (pH 6.8) fish-free emergent wetlands. Acidification of these wetlands suppressed phytoplankton and algal growth, and reduced invertebrate biomass. Ducklings maintained on acidified wetlands grew poorly compared with ducklings reared on circumneutral wetlands, as evidenced by lower final body weight and culmen and tarsus length. Plasma growth hormone concentration was elevated and triiodothyronine levels were lower in stunted ducklings, in part substantiating impairment of growth-regulating processes. Ducklings exhibiting poor growth tended to have lower hematocrit, lower plasma protein, glucose, and cholesterol concentrations, and higher uric acid levels, presumably reflecting alterations in metabolism and development due to inanition. These findings suggest that acid deposition may lower food production in wetlands and ultimately impair duckling growth, condition, and survival.

  20. Anaerobic digestion of sulfate-acidified cattle slurry: One-stage vs. two-stage.

    PubMed

    Moset, Veronica; Ottosen, Lars Ditlev Mørck; Xavier, Cristiane de Almeida Neves; Møller, Henrik Bjarne

    2016-05-15

    Two strategies to include acidified cattle manure (AcCM) in co-digestion with normal cattle manure (CM) are presented in this work. The strategies are a single thermophilic (50 °C) continuous stirred tank reactor (CSTR) anaerobic digestion and a two-step (65 °C + 50 °C) CSTR process. In both strategies, two different inclusion levels of H2SO4-acidified CM (10% and 20%) in co-digestion with normal CM were tested and compared with a control CSTR fed only CM. Important enhancement of methane (CH4) yield and solid reductions were observed in the thermophilic one-step CSTR working with 10% AcCM. However, a higher inclusion level of AcCM (20%) caused volatile fatty acid accumulation in the reactor and a more than 30% reduction in CH4 production. In terms of CH4 production, when 10% of AcCM was co-digested with 90% of CM, the two-step anaerobic co-digestion yielded less than the single step. During the first step of the two-step CSTR process, acidogenesis and a partial sulfate reduction were achieved. However, sulfide stripping between the first and the second step must be promoted in order to advance this technology. PMID:26985731

  1. [Decoloration of reactive turquoise blue by acidified sludge-bentonite granule].

    PubMed

    Yue, Qin-Yan; Yuan, Ai-Juan; Li, Qian; Gao, Bao-Yu; Li, Jing

    2009-05-15

    Using sludge as pore-forming agent, bentonite granule was acidified by sulfuric acid solution as a decolorant. The specific surface area and SEM were performed to characterize the structure of samples, and the new acidified sludge-bentonite granule was applied to the decoloration of reactive turquoise blue. The influencing factors of pH value, dosage, reaction time and reaction temperature were studied on the removal of the dyes. The important thermodynamics parameters (DeltaH0, DeltaS0, DeltaG) and the activation energy Ea were also acquired by experiment data processing. The results indicated that the adsorption isotherm fitted the isothermal adsorption equations of Langmuir better than Freundlich. The adsorption dynamics followed the law of the pseudo-second order kinetic equation, while the adsorption rate is 313 K > 303 K > 293 K. The low value of Ea which is 5.52 kJ x mol(-1) shows that physical adsorption is primary. And DeltaH0 > TDeltaS0 means that the influence of enthalpy is more remarkable than the entropy in the activation reaction. DeltaG > 0 also means the chemical reactions are not spontaneous.

  2. Forests and Soil Erosion across Europe

    NASA Astrophysics Data System (ADS)

    Bathurst, J. C.

    2012-04-01

    Land use and climate change threaten the ability of Europe's forests to provide a vital service in limiting soil erosion, e.g. from forest fires and landslides. However, our ability to define the threat and to propose mitigation measures suffers from two deficiencies concerning the forest/erosion interface: 1) While there have been a considerable number of field studies of the relationship between forest cover and erosion in different parts of Europe, the data sets are scattered among research groups and a range of literature outlets. There is no comprehensive overview of the forest/erosion interface at the European scale, essential for considering regional variations and investigating the effects of future changes in land use and climate. 2) Compared with forest/water studies, we have a poorer quantitative appreciation of forest/erosion interactions. In the forest/water area it is possible to make quantitative statements such as that a 20% change in forest cover across a river catchment is needed for the effect on annual water yield to be measurable or that a forested catchment in upland UK has an annual water yield around 15% lower than an otherwise comparable grassland catchment. Comparable statements are not yet possible for forest/erosion interactions and there are uncertainties in the mathematical representation of forest/erosion interactions which limit our ability to make predictions, for example of the impact of forest loss in a given area. This presentation therefore considers the next step in improving our predictive capability. It proposes the integration of existing research and data to construct the "big picture" across Europe, i.e. erosion rates and sediment yields associated with forest cover and its loss in a range of erosion regimes (e.g. post-forest fire erosion or post-logging landslides). This would provide a basis for generalizations at the European scale. However, such an overview would not form a predictive capability. Therefore it is also

  3. Overland flow generation in two lithologically distinct rainforest catchments

    USGS Publications Warehouse

    Godsey, S.; Elsenbeer, H.; Stallard, R.

    2004-01-01

    Streams on uniformly rainforest-covered, but lithologically very diverse Barro Colorado Island in central Panama?? show remarkable differences in their runoff response to rainfall. This lithological diversity is reflected in equally diverse soilscapes, and our objective was to test the hypothesis that contrasting runoff responses derive from soilscape features that control the generation of overland flow. We determined the soil saturated hydraulic conductivity (Ks) of two neighboring, but hydrologically contrasting catchments (Lutz Creek with a flashy and Conrad Trail with a delayed response to rainfall), and quantified the spatial and temporal frequency of overland flow occurrence. The median Ks values at a depth of 12.5 cm are large enough to rule out Hortonian overland flow, but a marked decrease in K s in Lutz Creek catchment at 30 cm suggests the formation of a perched water table and the generation saturation overland flow; the decrease in Ks in the Conrad Trail catchment is more gradual, and a perched water table is expected to form only at depths below 50 cm. In Lutz Creek, overland flow was generated frequently in time and space and regardless of topographic position, including near the interfluve, with very low thresholds of storm magnitude, duration, intensity and antecedent wetness, whereas in Conrad Trail, overland flow was generated much less frequently and then only locally. We conclude that soilscape features and microtopography are important controls of overland flow generation in these catchments. Our results contribute to the growing evidence that overland flow and forests are not a priori a contradiction in terms. ?? 2004 Elsevier B.V. All rights reserved.

  4. Use of a forest sapwood area index to explain long-term variability in mean annual evapotranspiration and streamflow in moist eucalypt forests

    NASA Astrophysics Data System (ADS)

    Benyon, Richard G.; Lane, Patrick N. J.; Jaskierniak, Dominik; Kuczera, George; Haydon, Shane R.

    2015-07-01

    Mean sapwood thickness, measured in fifteen 73 year old Eucalyptus regnans and E. delegatensis stands, correlated strongly with forest overstorey stocking density (R2 0.72). This curvilinear relationship was used with routine forest stocking density and basal area measurements to estimate sapwood area of the forest overstorey at various times in 15 research catchments in undisturbed and disturbed forests located in the Great Dividing Range, Victoria, Australia. Up to 45 years of annual precipitation and streamflow data available from the 15 catchments were used to examine relationships between mean annual loss (evapotranspiration estimated as mean annual precipitation minus mean annual streamflow), and sapwood area. Catchment mean sapwood area correlated strongly (R2 0.88) with catchment mean annual loss. Variation in sapwood area accounted for 68% more variation in mean annual streamflow than precipitation alone (R2 0.90 compared with R2 0.22). Changes in sapwood area accounted for 96% of the changes in mean annual loss observed after forest thinning or clear-cutting and regeneration. We conclude that forest inventory data can be used reliably to predict spatial and temporal variation in catchment annual losses and streamflow in response to natural and imposed disturbances in even-aged forests. Consequently, recent advances in mapping of sapwood area using airborne light detection and ranging will enable high resolution spatial and temporal mapping of mean annual loss and mean annual streamflow over large areas of forested catchment. This will be particularly beneficial in management of water resources from forested catchments subject to disturbance but lacking reliable long-term (years to decades) streamflow records.

  5. Forest blowdown and lake acidification

    SciTech Connect

    Dobson, J.E.; Rush, R.M. ); Peplies, R.W. )

    1990-01-01

    The authors examine the role of forest blowdown in lake acidification. The approach combines geographic information systems (GIS) and digital remote sensing with traditional field methods. The methods of analysis consist of direct observation, interpretation of satellite imagery and aerial photographs, and statistical comparison of two geographical distributions-one representing forest blow-down and another representing lake chemistry. Spatial and temporal associations between surface water pH and landscape disturbance are strong and consistent in the Adirondack Mountains of New York. In 43 Adirondack Mountain watersheds, lake pH is associated with the percentage of the watershed area blown down and with hydrogen ion deposition (Spearman rank correlation coefficients of {minus}0.67 and {minus}0.73, respectively). Evidence of a temporal association is found at Big Moose Lake and Jerseyfield Lake in New York and the Lygners Vider Plateau of Sweden. They conclude that forest blowdown facilities the acidification of some lakes by altering hydrologic pathways so that waters (previously acidified by acid deposition and/or other sources) do not experience the neutralization normally available through contact with subsurface soils and bedrock. Increased pipeflow is suggested as a mechanism that may link the biogeochemical impacts of forest blowdown to lake chemistry.

  6. Catchment Prediction In Changing Environments (CAPICHE): A Model Inter-Comparison Experiment

    NASA Astrophysics Data System (ADS)

    Hutton, Christopher; Nijzink, Remko; Pechlivanidis, Ilias; Capell, René; Wagener, Thorsten; Freer, Jim; Han, Dawei; Hrachowitz, Markus; Arheimer, Berit

    2016-04-01

    In order to improve societal resilience to the impacts of changes in climate and land-use, improved understanding of how catchments respond to changing forcing conditions is required. Such understanding may help better identify the range of effective interventions to improve overall integrated catchment management. For example, re-foresting catchment headwaters may reduce high flows, but also reduce low flows through increased evapotranspiration, creating a potential trade-off that needs to be reliably understood when considering benefits for both water supply and flood mitigation. Catchment modelling may be useful to inform such management decisions by simulating future forcing changes, so that we can assess the relative benefits of different catchment management scenarios. However, numerical models are known to be uncertain, and their ability to simulate future change is compromised by the fact that model parameters can show non-stationary and compensatory effects for different forcing conditions, notwithstanding errors and uncertainties in the future forcings themselves. In order to first identify, and second develop the most appropriate models to simulate catchments under environmental change, we argue that model inter-comparisons are required that move beyond a simple comparison of predictive performance alone, towards a controlled comparison of how different models simulate change. We present the development of a methodology for model inter-comparison under changing forcings to analyse, in this case, how models simulate landscape change, built upon time-varying sensitivity analysis of model parameters. First, for a given catchment, hydrologic signatures are calculated over consecutive windows covering the period of forcing change to analyse how the catchment responds hydrologically to change. Then, each model is calibrated to each window, and within each window, to each signature, which allows us to analyse the time-varying relationship between catchment

  7. Land-use change in the Atlantic rainforest region: Consequences for the hydrology of small catchments

    NASA Astrophysics Data System (ADS)

    Salemi, Luiz Felippe; Groppo, Juliano Daniel; Trevisan, Rodrigo; de Moraes, Jorge Marcos; de Barros Ferraz, Silvio Frosini; Villani, João Paulo; Duarte-Neto, Paulo José; Martinelli, Luiz Antonio

    2013-08-01

    The Atlantic forest of Brazil is one of the most endangered ecosystems in the world. Despite approximately 500 years of intense land-use change in this biome, the influence of land-use changes on hydrological processes have yet to be investigated in-depth. To bridge this gap, we studied various features of three small catchments covered by pristine original montane cloud forest, pasture, and eucalyptus for 2 years (January 2008-December 2009), including the hydraulic properties of soils, throughfall, overland flow and streamflow processes. The forest saturated hydraulic conductivity (Ksat) was higher near the soil surface (0.15 m depth) compared to eucalyptus and pasture. As a consequence, higher overland flow generation in terms of volume was observed in pasture and eucalyptus. Despite this increase in overland flow generation, overland flow coefficients (overland flow: precipitation ratio) were substantially low throughout the study period with slightly higher values in 2009. These low overland flow coefficients were attributed to the large predominance of low rainfall intensities (<10 mm h-1) as well as high Ksat spatial variability. These overland flow results and the absence of perched water table showed that catchments seem still to be dominated by vertical flowpaths irrespective of land-use. In this sense, the annual streamflow is still dominated by baseflow in all of the catchments. Therefore, despite reductions regarding interception and saturated hydraulic conductivity when converting forest to eucalyptus and pasture, the prevailing rainfall intensities do not cause runoff generation processes to be substantially different among land-uses. Forest and eucalyptus convert a similar proportion of annual precipitation to annual streamflow, with the more likely factors for these results being the high interception under forest and high transpiration under eucalyptus. Finally, cloud forest conversion to pasture does not promote significant monthly streamflow

  8. Forest liming increases forest floor carbon and nitrogen stocks in a mixed hardwood forest.

    PubMed

    Melvin, April M; Lichstein, Jeremy W; Goodale, Christine L

    2013-12-01

    In acid-impacted forests, decreased soil pH and calcium (Ca) availability have the potential to influence biotic and abiotic controls on carbon (C) and nitrogen (N) cycling. We investigated the effects of liming on above- and belowground C and N pools and fluxes 19 years after lime addition to the Woods Lake Watershed, Adirondack Park, New York, USA. Soil pH and exchangeable Ca remained elevated in the forest floor and upper mineral soil of limed areas. Forest floor C and N stocks were significantly larger in limed plots (68 vs. 31 Mg C/ha, and 3.0 vs. 1.5 Mg N/ha), resulting from a larger mass of Oa material. Liming reduced soil basal respiration rates by 17% and 43% in the Oe and Oa horizons, respectively. Net N mineralization was significantly lower in the limed soils for both forest floor horizons. Additional measurements of forest floor depth outside of our study plots, but within the treatment and control subcatchments also showed a deeper forest floor in limed areas; however, the mean depth of limed forest floor was 5 cm shallower than that observed in our study plots. Using a differential equation model of forest floor C dynamics, we found that liming effects on C fluxes measured within our study plots could explain the small observed increase in the Oe C stock but were not large enough to explain the increase in the Oa. Our catchment-wide assessment of forest floor depth, however, indicates that our plot analysis may be an overestimate of ecosystem-scale C and N stocks. Our results suggest that the mechanisms identified in our study, primarily liming-induced reduction in decomposition rates, may account for much of the observed increase in forest floor C. These findings emphasize the importance of understanding of the effects of liming in hardwood forests, and the long-term impacts of acid deposition on forest C and N uptake and retention.

  9. How tritium illuminates catchment structure

    NASA Astrophysics Data System (ADS)

    Stewart, M.; Morgenstern, U.; McDonnell, J.

    2012-04-01

    Streams contain water which has taken widely-varying times to pass through catchments, and the distribution of ages is likely to change with the flow. Part of the water has 'runoff' straight to the stream with little delay, other parts are more delayed and some has taken years (in some cases decades) to traverse the deeper regolith or bedrock of the catchment. This work aims to establish the significance of the last component, which is important because it can cause catchments to have long memories of contaminant inputs (e.g. nitrate). Results of tritium studies on streams world-wide were accessed from the scientific literature. Most of the studies assumed that there were just two age-components present in the streams (i.e. young and old). The mean ages and proportions of the components were found by fitting simulations to tritium data. It was found that the old component in streams was substantial (average was 50% of the annual runoff) and had considerable age (average mean age was 10 years) (Stewart et al., 2010). Use of oxygen-18 or chloride variations to estimate streamflow mean age usually does not reveal the age or size of this old component, because these methods cannot detect water older than about four years. Consequently, the use of tritium has shown that substantial parts of streamflow in headwater catchments are older than expected, and that deep groundwater plays an active and sometimes even a dominant role in runoff generation. Difficulties with interpretation of tritium in streams in recent years due to interference from tritium due to nuclear weapons testing are becoming less serious, because very accurate tritium measurements can be made and there is now little bomb-tritium remaining in the atmosphere. Mean ages can often be estimated from single tritium measurements in the Southern Hemisphere, because there was much less bomb-tritium in the atmosphere. This may also be possible for some locations in the Northern Hemisphere. Age determination on

  10. A new, catchment-scale model for simulating methyl and total mercury in soils and surface waters

    NASA Astrophysics Data System (ADS)

    Futter, M. N.; Poste, A. E.; Whitehead, P. G.; Dillon, P. J.

    2012-04-01

    Mercury (Hg) is a potent and persistent neurotoxin. It is subject to long-range atmospheric transport, accumulates in catchment soils, and can pose health risks to humans and animals both at the point of use as well as in remote locations. Elevated concentrations of methyl mercury (MeHg) in fish are related to atmospheric Hg deposition and have resulted in fish consumption advisories in many parts of North America and Fennoscandia. After more than 150 years of elevated Hg deposition in Europe and North America, there remains a large inventory of Hg in the terrestrial catchments of lakes, which continues to be exported to receiving waters despite decreasing atmospheric inputs. While a substantial Hg pool exists in boreal catchment soils, fluxes of Hg from catchments via stream runoff tend to be much lower than atmospheric Hg inputs. Terrestrial catchments receiving similar atmospheric Hg inputs can have markedly different patterns of Hg output in stream water. Considering the importance of catchment processes in determining Hg flux to lakes and subsequent MeHg concentrations in fish, there is a need to characterize Hg cycling and transport in boreal and temperate forest-covered catchments. We present a new, catchment-scale, process-based dynamic model for simulating Hg in soils and surface waters. The Integrated Catchments Model for Mercury (INCA-Hg) simulates transport of gaseous, dissolved and solid Hg and transformations between elemental (Hg0), ionic (Hg(II)) and MeHg in natural and semi-natural landscapes. The mathematical description represents the model as a series of linked, first-order differential equations describing chemical and hydrological processes in catchment soils and waters which control surface water Hg dynamics and subsequent fluxes to lakes and other receiving waters. The model simulates daily time series between one and one hundred years long and can be applied to catchments ranging in size from <1 to ~10000 km2. Here we present applications

  11. Forest Management.

    ERIC Educational Resources Information Center

    Weicherding, Patrick J.; And Others

    This bulletin deals with forest management and provides an overview of forestry for the non-professional. The bulletin is divided into six sections: (1) What Is Forestry Management?; (2) How Is the Forest Measured?; (3) What Is Forest Protection?; (4) How Is the Forest Harvested?; (5) What Is Forest Regeneration?; and (6) What Is Forest…

  12. Climatic and Catchment-Scale Predictors of Chinese Stream Insect Richness Differ between Taxonomic Groups.

    PubMed

    Tonkin, Jonathan D; Shah, Deep Narayan; Kuemmerlen, Mathias; Li, Fengqing; Cai, Qinghua; Haase, Peter; Jähnig, Sonja C

    2015-01-01

    Little work has been done on large-scale patterns of stream insect richness in China. We explored the influence of climatic and catchment-scale factors on stream insect (Ephemeroptera, Plecoptera, Trichoptera; EPT) richness across mid-latitude China. We assessed the predictive ability of climatic, catchment land cover and physical structure variables on genus richness of EPT, both individually and combined, in 80 mid-latitude Chinese streams, spanning a 3899-m altitudinal gradient. We performed analyses using boosted regression trees and explored the nature of their influence on richness patterns. The relative importance of climate, land cover, and physical factors on stream insect richness varied considerably between the three orders, and while important for Ephemeroptera and Plecoptera, latitude did not improve model fit for any of the groups. EPT richness was linked with areas comprising high forest cover, elevation and slope, large catchments and low temperatures. Ephemeroptera favoured areas with high forest cover, medium-to-large catchment sizes, high temperature seasonality, and low potential evapotranspiration. Plecoptera richness was linked with low temperature seasonality and annual mean, and high slope, elevation and warm-season rainfall. Finally, Trichoptera favoured high elevation areas, with high forest cover, and low mean annual temperature, seasonality and aridity. Our findings highlight the variable role that catchment land cover, physical properties and climatic influences have on stream insect richness. This is one of the first studies of its kind in Chinese streams, thus we set the scene for more in-depth assessments of stream insect richness across broader spatial scales in China, but stress the importance of improving data availability and consistency through time.

  13. Determination of 5-log reduction times for food pathogens in acidified cucumbers during storage at 10 and 25°C

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Outbreaks of acid-resistant food pathogens in acid foods with pH values below 4.0, including apple cider and orange juice, have raised concerns about the safety of acidified vegetable products. For acidified vegetable products with pH values between 3.3 and 4.6, previous research has demonstrated t...

  14. Estimating Chemical Exchange between Atmospheric Deposition and Forest Canopy in Guizhou, China.

    PubMed

    Li, Wei; Gao, Fang; Liao, Xueqin

    2013-01-01

    To evaluate the effects of atmospheric deposition on forest ecosystems, wet-only precipitation and throughfall samples were collected in two forest types (Masson pine [ Lamb.] forests and mixed conifer and broadleaf forests) in the Longli forest in the Guizhou province of southwestern China for a period of 21 successive months from April 2007 to December 2008. The pH and chemical components of precipitation and throughfall were analyzed. In addition, the canopy budget model was applied to distinguish between in-canopy and atmospheric sources of chemical compounds. Canopy leaching and total potentially acidifying deposition fluxes were calculated. The results showed that the average pH and the concentration of ions in throughfall were higher than those in precipitation, with the exception of the NH concentration. Dry deposition of S and N accumulated more in Masson pine forests than in mixed conifer and broadleaf forests. Canopy leaching was the most significant source of base cations in forest throughfall, which was higher in the mixed forests than in the coniferous forests. Anions in throughfall deposition in Masson pine forests exceeded those in the mixed forests. Higher total potentially acidifying deposition fluxes reflected the more effective amounts of acid delivered to Masson pine forests compared with mixed conifer and broadleaf forests. In addition, acid deposition induced the leaching and loss of nutrient ions such as Mg, K, and Ca. Although the trees of the studied areas have not shown any symptoms of cation loss, a potentially harmful influence was engendered by atmospheric deposition in the two forest types in the Longli area.

  15. Estimating Chemical Exchange between Atmospheric Deposition and Forest Canopy in Guizhou, China.

    PubMed

    Li, Wei; Gao, Fang; Liao, Xueqin

    2013-01-01

    To evaluate the effects of atmospheric deposition on forest ecosystems, wet-only precipitation and throughfall samples were collected in two forest types (Masson pine [ Lamb.] forests and mixed conifer and broadleaf forests) in the Longli forest in the Guizhou province of southwestern China for a period of 21 successive months from April 2007 to December 2008. The pH and chemical components of precipitation and throughfall were analyzed. In addition, the canopy budget model was applied to distinguish between in-canopy and atmospheric sources of chemical compounds. Canopy leaching and total potentially acidifying deposition fluxes were calculated. The results showed that the average pH and the concentration of ions in throughfall were higher than those in precipitation, with the exception of the NH concentration. Dry deposition of S and N accumulated more in Masson pine forests than in mixed conifer and broadleaf forests. Canopy leaching was the most significant source of base cations in forest throughfall, which was higher in the mixed forests than in the coniferous forests. Anions in throughfall deposition in Masson pine forests exceeded those in the mixed forests. Higher total potentially acidifying deposition fluxes reflected the more effective amounts of acid delivered to Masson pine forests compared with mixed conifer and broadleaf forests. In addition, acid deposition induced the leaching and loss of nutrient ions such as Mg, K, and Ca. Although the trees of the studied areas have not shown any symptoms of cation loss, a potentially harmful influence was engendered by atmospheric deposition in the two forest types in the Longli area. PMID:23673825

  16. Shift from coral to macroalgae dominance on a volcanically acidified reef

    NASA Astrophysics Data System (ADS)

    Enochs, I. C.; Manzello, D. P.; Donham, E. M.; Kolodziej, G.; Okano, R.; Johnston, L.; Young, C.; Iguel, J.; Edwards, C. B.; Fox, M. D.; Valentino, L.; Johnson, S.; Benavente, D.; Clark, S. J.; Carlton, R.; Burton, T.; Eynaud, Y.; Price, N. N.

    2015-12-01

    Rising anthropogenic CO2 in the atmosphere is accompanied by an increase in oceanic CO2 and a concomitant decline in seawater pH (ref. ). This phenomenon, known as ocean acidification (OA), has been experimentally shown to impact the biology and ecology of numerous animals and plants, most notably those that precipitate calcium carbonate skeletons, such as reef-building corals. Volcanically acidified water at Maug, Commonwealth of the Northern Mariana Islands (CNMI) is equivalent to near-future predictions for what coral reef ecosystems will experience worldwide due to OA. We provide the first chemical and ecological assessment of this unique site and show that acidification-related stress significantly influences the abundance and diversity of coral reef taxa, leading to the often-predicted shift from a coral to an algae-dominated state. This study provides field evidence that acidification can lead to macroalgae dominance on reefs.

  17. Leaching behaviour and environmental risk assessment of heavy metals from electronic solder in acidified soil.

    PubMed

    Lao, Xiaodong; Cheng, Congqian; Min, Xiaohua; Zhao, Jie; Zhou, Dayu; Li, Xiaogang

    2015-11-01

    The leaching behaviour of Sn and Pb elements from eutectic SnPb solder of electronic waste in acidic soil was investigated through acidification with HCl-H2SO4 solution and compared with saline solution. The amounts of Sn and Pb elements leached, when subjected to acidic soil, are higher than those with saline soil. Evidence for the significantly preferential release of Sn into the leachate is provided; the galvanic couple accelerated such preferential release. Surface product analysis reveals the slight damage of SnPb in saline soil. Serious dissolution due to electrochemical reaction and a thick, porous PbSO4 surface layer are observed in acidified soil, suggesting more severe toxicity potential of Pb in soil rather than in water. PMID:26154035

  18. Ethanol-based in situ bioremediation of acidified, nitrate-contaminated groundwater.

    PubMed

    Salminen, Jani M; Petäjäjärvi, Sanna J; Tuominen, Sirkku M; Nystén, Taina H

    2014-10-15

    A novel approach for the in situ bioremediation of acidified, nitrate-contaminated groundwater was developed. Ethanol was introduced into the groundwater to enhance the activity of intrinsic denitrifying micro-organisms. Infiltration of the carbon source was made via an infiltration gallery constructed in the unsaturated zone to avoid clogging problems and to allow wider distribution of ethanol in the groundwater. The changes in the groundwater geochemistry and soil gas composition were monitored at the site to evaluate the efficiencies of the infiltration system and nitrate removal. Moreover, the impact of pH and ethanol addition on the denitrification rate was studied in laboratory. A reduction of 95% was achieved in the groundwater nitrate concentrations during the study. Neither clogging problems nor inefficient introduction of ethanol into the saturated zone were observed. Most crucial to the denitrifying communities was pH, values above 6 were required for efficient denitrification.

  19. Laboratory and pilot scale pretreatment of sugarcane bagasse by acidified aqueous glycerol solutions.

    PubMed

    Zhang, Zhanying; Wong, Heng H; Albertson, Peter L; Doherty, William O S; O'Hara, Ian M

    2013-06-01

    Pretreatment of sugarcane bagasse with acidified aqueous glycerol solution was evaluated at both laboratory and pilot scales. Laboratory scale pretreatment (4.00 g dry mass in 40.00 g liquid) with glycerol solutions containing ≤ 20 wt.% water and 1.2 wt.% HCl at 130°C for 60 min resulted in biomass having glucan digestibilities of ≥ 88%. Comparable glucan enzymatic digestibility of 90% was achieved with bagasse pretreated at pilot scale (10 kg dry mass in 60 kg liquid) using a glycerol solution containing 0.4 wt.% HCl and 17 wt.% water at 130°C for 15 min. We attribute more efficient pretreatment at pilot scale (despite shorter reaction time and reduced acid content) to improved mixing and heat transfer in a horizontal reactor. Pretreatment of sugarcane bagasse with acid-catalysed glycerol solutions likely produces glycerol-glycosides, which together with hydrolysed lignin are potential substrates for the production of biopolymers.

  20. Estimating sedimentation rates and sources in a partially urbanized catchment using caesium-137

    NASA Astrophysics Data System (ADS)

    Ormerod, L. M.

    1998-06-01

    While there has been increased interest in determining sedimentation rates and sources in agricultural and forested catchments in recent years, there have been few studies dealing with urbanized catchments. A study of sedimentation rates and sources within channel and floodplain deposits of a partially urbanized catchment has been undertaken using the 137Cs technique. Results for sedimentation rates showed no particular downstream pattern. This may be partially explained by underestimation of sedimentation rates at some sites by failure to sample the full 137Cs profile, floodplain erosion and deliberate removal of sediment. Evidence of lateral increases in net sedimentation rates with distance from the channel may be explained by increased floodplain erosion at sites closer to the channel and floodplain formation by lateral deposition. Potential sediment sources for the catchment were considered to be forest topsoil, subsurface material and sediments derived from urban areas, which were found to be predominantly subsurface material. Tracing techniques showed an increase in subsurface material for downstream sites, confirming expectations that subsurface material would increase in the downstream direction in response to the direct and indirect effects of urbanization.

  1. [Differences in urbanization process of catchments in dongjiang watershed and their effects on landscape pattern].

    PubMed

    Ren, Wen-tao; Peng, Shao-lin; Zhou, Ting; Li, Yan

    2008-12-01

    Based on 1991, 1998, and 2006 TM images, the areas of different land use types and the landscape indices of three catchments (catchment a, b, and c, which represented upper, middle, and lower reaches, respectively) in Dongjiang watershed were analyzed, aimed to study the differences in urbanization process along Dongjiang River, and their effects on landscape pattern. The results showed that the degree and speed of urbanization increased from the upper to the lower reach of Dongjiang River. Urbanization had significantly effects on water and vegetation. Urban land area was positively correlated with water body area, and negatively correlated with forest land area. However, to some extent, urbanization stepped into a relatively high degree might benefit forest recovery. The landscape pattern of catchments a and b kept complicating from 1991 to 2006, while that of catchment c was getting complex from 1991 to 1998 and then becoming simple from 1998 to 2006, indicating that with the development of urbanization, landscape pattern presented a "simple-complex-simple" tendency. Understanding the change patterns of the landscape pattern along Dongjiang River would benefit the management and sustainable development of the watershed as a whole.

  2. Acidifier application rate impacts on ammonia emissions from US roaster chicken houses

    NASA Astrophysics Data System (ADS)

    Shah, Sanjay B.; Grimes, Jesse L.; Oviedo-Rondón, Edgar O.; Westerman, Philip W.

    2014-08-01

    Due to its potential environmental and public health impacts, emissions of ammonia (NH3) as well as several other gases from US livestock farms may be regulated. Broiler houses are important sources of NH3 emissions. However, there are no emissions data from roaster (8-12 wk old broilers, ˜4 kg ea.) houses. Producers treat the litter in broiler houses with acidifiers, such as sodium bisulfate (SBS, NaHSO4) to reduce ammonia production and protect bird health. However, there is very little data on the effect of acidifiers, particularly at high application rates on ammonia emissions. The impact of different SBS application rates [High (0.95-1.46 kg m-2, whole house), Medium (0.73 kg m-2, whole house), Low (0.37-0.49 kg m-2, whole house), and Control (0.37-0.49 kg m-2, brood chamber)] on ammonia emissions was evaluated in commercial roaster houses over 22 months spanning eight flocks. Ammonia emission from each fan was measured with an acid scrubber that operated only when the fan operated. Emissions were calculated using >95% measured data with the rest being estimated using robust methods. Exhaust ammonia-N concentrations were inversely correlated with the SBS application rates. Emission rates on animal unit (AU, where 1 AU = 500 kg live-mass) basis (ER, g d-1 AU-1) were reduced by 27, 13, and 5%, respectively, in the High, Medium, and Low treatments vs. the Control treatment (mean: 100 g d-1 AU-1, range: 86-114 g d-1 AU-1). Emission rates for the Control treatment measured in this study on roasters were mostly higher than ERs in the literature. Differences in ERs are not only due to diet, environmental and management conditions, but also due to measurement methods.

  3. Fatty acid composition and biogenic amines in acidified and fermented fish silage: a comparison study.

    PubMed

    Özyurt, Gülsün; Gökdoğan, Saadet; Şimşek, Ayşe; Yuvka, Ilknur; Ergüven, Merve; Kuley Boga, Esmeray

    2016-01-01

    In the presented study, ensiling of discard fish by acidification or fermentation was evaluated. Klunzinger's ponyfish which is a discard fish was used for the production of fish silage by acidification (3% formic acid for Method FA; 1.5% formic and 1.5% sulphuric acid for Method FASA) and fermentation (Lactobacillus plantarum for Method LP and Streptococcus thermophilus for Method ST). The chemical, microbiological and nutritional properties of the differently preserved fish silages were estimated during a storage period of 60 d at ambient temperature. Compared to the raw material, a slight increase in saturated fatty acids and a slight decrease in polyunsaturated fatty acids were observed in all silages. At the end of the storage period, the aerobic bacteria counts after applying Methods FA, FASA, LP and ST amounted to 2.35, 2.39, 5.77 and 5.43 log cfu/g, respectively. The analysis of thiobarbituric acid revealed that acidification of silages accelerated the lipid oxidation. Nine biogenic amines were found in raw fish and different silages. The initial histamine concentration in raw fish was 0.17 mg/100 g and in all silages it remained at low levels during the storage period. The initial tyramine content was found to be 1.56 mg/100 g in raw fish and increased significantly in all silages. The increase of the tyramine content in fermented silages was considerably higher than in acidified silages (23-48 mg/100 g and 5-10 mg/100 g, respectively). It can be concluded that acidified or fermented fish silage should be considered as potential feed component for animals because of its high nutritional value and appropriate microbiological and chemical quality.

  4. Fatty acid composition and biogenic amines in acidified and fermented fish silage: a comparison study.

    PubMed

    Özyurt, Gülsün; Gökdoğan, Saadet; Şimşek, Ayşe; Yuvka, Ilknur; Ergüven, Merve; Kuley Boga, Esmeray

    2016-01-01

    In the presented study, ensiling of discard fish by acidification or fermentation was evaluated. Klunzinger's ponyfish which is a discard fish was used for the production of fish silage by acidification (3% formic acid for Method FA; 1.5% formic and 1.5% sulphuric acid for Method FASA) and fermentation (Lactobacillus plantarum for Method LP and Streptococcus thermophilus for Method ST). The chemical, microbiological and nutritional properties of the differently preserved fish silages were estimated during a storage period of 60 d at ambient temperature. Compared to the raw material, a slight increase in saturated fatty acids and a slight decrease in polyunsaturated fatty acids were observed in all silages. At the end of the storage period, the aerobic bacteria counts after applying Methods FA, FASA, LP and ST amounted to 2.35, 2.39, 5.77 and 5.43 log cfu/g, respectively. The analysis of thiobarbituric acid revealed that acidification of silages accelerated the lipid oxidation. Nine biogenic amines were found in raw fish and different silages. The initial histamine concentration in raw fish was 0.17 mg/100 g and in all silages it remained at low levels during the storage period. The initial tyramine content was found to be 1.56 mg/100 g in raw fish and increased significantly in all silages. The increase of the tyramine content in fermented silages was considerably higher than in acidified silages (23-48 mg/100 g and 5-10 mg/100 g, respectively). It can be concluded that acidified or fermented fish silage should be considered as potential feed component for animals because of its high nutritional value and appropriate microbiological and chemical quality. PMID:26635094

  5. Eubiotic effect of a dietary acidifier (potassium diformate) on the health status of cultured Oreochromis niloticus.

    PubMed

    Abu Elala, Nermeen M; Ragaa, Naela M

    2015-07-01

    In connection with the global demand for safe human food and the production of environmentally friendly aquaculture products, acidifiers are natural organic acids and salts that have received considerable attention as animal-feed additives. The current study was designed to evaluate the effects of potassium diformate (KDF) on the growth performance and immunity of cultured Oreochromis niloticus (O. niloticus). Four iso-nitrogenous and iso-caloric rations containing graded levels of KDF, including 0% (control basal diet), 0.1%, 0.2% and 0.3%, were fed separately to four equal fish groups (30 fish/group with an initial body weight of 53.49 ± 6.15 g) for sixty days. At the end of the experimental period, the fish groups fed on 0.2% and 0.3% KDF exhibited significant improvements in their feed intake, live weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio, with concomitant improvement of their apparent protein digestibility (p < 0.05). Dietary supplementation of 0.3% KDF appeared to stimulate the beneficial intestinal flora; a proliferation was observed of indigenous probionts (Eubiosis) associated with the relative activation of cellular and humeral innate immunity (phagocytic activity/index, nitroblue tetrazolium reduction test and serum/gut mucous lysozyme activity). The cumulative mortality of the fish groups fed on KDF and challenged orally with Aeromonas hydrophila was lower than that of the control group. The resistance against diseases increased with dietary KDF in a dose-dependent manner. Thus, we conclude that the use of acidifiers can be an efficient tool to achieve sustainable, economical and safe fish production. PMID:26199753

  6. Catchment Sensitivity to Changing Climate Conditions: The Importance of Landscape Characteristics

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The scientific literature is full of studies analyzing future climate change impacts on hydrology with focus on individual catchments. We recently found, however, that hydrologic behavior and specific discharge vary considerably even in neighboring and rather similar catchments under current climate conditions and that these variations are related to landscape characteristics. Therefore we hypothesize that these landscape characteristics also play a fundamental role for the sensitivity of a catchment to changing climate conditions. We analyzed the hydrological response of 14 partially nested catchments in Northern Sweden with slightly different topography, land cover, size and geology. Current (1981-2010) and future (2061-2090) streamflows were simulated with the hydrological model HBV light based on 15 regional climate model projections that were bias-corrected with a distribution-mapping approach. Our simulations revealed that - in a future climate- the total annual streamflow will be higher, spring flood peaks will occur earlier and decrease considerably, whereas winter base flows will more than double. These changes are somewhat expected and mainly triggered by a projected increase in winter temperature, which leads to less snow accumulation on the ground. However, our results also show that there is a large variability amongst these catchments in their hydrological response to the same future climate conditions. We identified wetlands, lakes, peat soils and higher elevations as factors that had a stronger effect on spring floods, whereas catchments dominated by forests, steeper slopes and till soils showed stronger responses in winter base flows and total annual streamflow. Therefore, our results suggest that the sensitivity of catchments to future climate conditions is strongly linked to landscape characteristics and also depends on the streamflow characteristic as well as season analyzed.

  7. The missing flux in a 35S budget for the soils of a small polluted catchment

    USGS Publications Warehouse

    Novak, M.; Michel, R.L.; Prechova, E.; Stepanova, M.

    2004-01-01

    A combination of cosmogenic and artificial 35S was used to assess the movement of sulfur in a steep Central European catchment affected by spruce die-back. The Jezer??i?? catchment, Krus??ne?? Hory Mts. (Czech Republic) is characterized by a large disproportion between atmospheric S input and S output via stream discharge, with S output currently exceeding S input three times. A relatively high natural concentration of cosmogenic 35S (42 mBq L-1) was found in atmospheric deposition into the catchment in winter and spring of 2000. In contrast, stream discharge contained only 2 mBq L-1. Consequently, more than 95% of the deposited S is cycled or retained within the catchment for more than several months, while older S is exported via surface water. In spring, when the soil temperature is above 0 ??C, practically no S from instantaneous rainfall is exported, despite the steepness of the slopes and the relatively short mean residence time of water in the catchment (6.5 months). Sulfur cycling in the soil includes not just adsorption of inorganic sulfate and biological uptake, but also volatilization of S compounds back into the atmosphere. Laboratory incubations of an Orthic Podzol from Jezer??i?? spiked with h 720 kBq of artificial 35S showed a 20% loss of the spike within 18 weeks under summer conditions. Under winter conditions, the 35S loss was insignificant (< 5%). This missing S flux was interpreted as volatilized hydrogen sulfide resulting from intermittent dissimilatory bacterial sulfate reduction. The missing S flux is comparable to the estimated uncertainty in many catchment S mass balances (??10%), or even larger, and should be considered in constructing these mass balances. In severely polluted forest catchments, such as Jezer??i??, sulfur loss to volatilization may exceed 13 kg ha-1 a-1, which is more than the current total atmospheric S input in large parts of North America and Europe. ?? 2004 Kluwer Academic Publishers.

  8. Comparison of the effects of thermal stress and CO₂-driven acidified seawater on fertilization in coral Acropora digitifera.

    PubMed

    Iguchi, Akira; Suzuki, Atsushi; Sakai, Kazuhiko; Nojiri, Yukihiro

    2015-08-01

    Global warming (GW) and ocean acidification (OA) have been recognized as severe threats for reef-building corals that support coral reef ecosystems, but these effects on the early life history stage of corals are relatively unknown compared with the effects on calcification of adult corals. In this study, we evaluated the effects of thermal stress and CO2-driven acidified seawater on fertilization in a reef-building coral, Acropora digitifera. The fertilization rates of A. digitifera decreased in response to thermal stress compared with those under normal seawater conditions. In contrast, the changes of fertilization rates were not evident in the acidified seawater. Generalized Linear Mixed Model (GLMM) predicted that sperm/egg crosses and temperature were explanatory variables in the best-fitted model for the fertilization data. In the best model, interactions between thermal stress and acidified seawater on the fertilization rates were not selected. Our results suggested that coral fertilization is more sensitive to future GW than OA. Taking into consideration the previous finding that sperm motility of A. digitifera was decreased by acidified seawater, the decrease in coral cover followed by that of sperm concentration might cause the interacting effects of GW and OA on coral fertilization.

  9. Growth inhibition of Cronobacter spp. strains in reconstituted powdered infant formula acidified with organic acids supported by natural stomach acidity.

    PubMed

    Zhu, S; Schnell, S; Fischer, M

    2013-09-01

    Cronobacter is associated with outbreaks of rare, but life-threatening cases of meningitis, necrotizing enterocolitis, and sepsis in newborns. This study was conducted to determine the effect of organic acids on growth of Cronobacter in laboratory medium and reconstituted powdered infant formula (PIF) as well as the bacteriostatic effect of slightly acidified infant formula when combined with neonatal gastric acidity. Inhibitory effect of seven organic acids on four acid sensitive Cronobacter strains was determined in laboratory medium with broth dilution method at pH 5.0, 5.5 and 6.0. Acetic, butyric and propionic acids were most inhibitive against Cronobacter in the laboratory medium. The killing effect of these three acids was partially buffered in reconstituted PIF. Under neonatal gastric acid condition of pH 5.0, the slightly acidified formula which did not exert inhibition effect solely reduced significantly the Cronobacter populations. A synergistic effect of formula moderately acidified with organic acid combined with the physiological infant gastric acid was visible in preventing the rapid growth of Cronobacter in neonatal stomach. The study contributed to a better understanding of the inhibitory effect of organic acids on Cronobacter growth in different matrixes and provided new ideas in terms of controlling bacteria colonization and translocation by acidified formula.

  10. Trends in Surface Water Chemistry in Acidified Areas in Europe and North America from 1990 to 2008

    EPA Science Inventory

    Acidification of lakes and rivers is still an environmental concern despite reduced emissions of acidifying compounds. We analyzed trends in surface water chemistry of 173 acid-sensitive sites from 12 regions in Europe and North America. In 11 of 12 regions, non-marine sulphate (...

  11. Thermal processing of acidified foods with pH 4.1 to pH 4.6

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shelf-stable acidified foods with a pH at or below 4.6 must be processed to achieve a 5-log reduction for vegetative bacterial pathogens. Published research does not exist to adequately support the Food and Drug Administration process filings for products with pH 4.1–4.6 or to define critical limits...

  12. Linking the field to the stream: soil erosion and sediment yield in a rural catchment, NW Spain

    NASA Astrophysics Data System (ADS)

    Rodriguez-Blanco, M. L.; Taboada-Castro, M. M.; Palleiro-Suarez, L.; Taboada-Castro, M. T.

    2009-04-01

    Quantifying the linkages between field erosion, fluvial response and catchment sediment yield remains problematic, among other reasons, because of the re-deposition of eroded sediment within the catchment, which is controlled by the spatial organization of the land use and the connectivity between sediment sources and the stream network. This paper presents the results of an integrated study that considered the relationship between erosion and stream sediment yield in an agroforestry catchment (16 km2) in NW Spain. The geology consists of basic metamorphic schist. The relieve of the area is steeper, the mean slope is approximately 19%. Main soil types are classified as Umbrisol and Cambisol. Soils are acidic and rich in organic matter. The soil texture is silt and silt-loam. Land cover consists of a mixture of forest (65%) and agricultural fields (mainly grassland, pasture and maize). The study combined measurements of soil erosion by concentrate flow and sediment deposition at field scale with sediment yield measured at the catchment outlet. The hydrological data and water samples were obtained at the catchment outlet. Stream water level was monitored continuously and converted to discharge using a rating curve. The sampling for suspended sediments was supplemented by an automatic sampler. Suspended sediment load was calculated from the suspended sediment concentrations and discharge data. Eroded volume was calculated from cross-sections (measured at specific points, where the section changed abruptly) and length of the channel segments. The total sediment delivered to stream was determined as the difference between all erosion features (rills and gullies) and the sediment volumes that were deposited on the fields. The results showed that in the catchment during the period winter 2007/08 soil erosion by concentrate flow, i.e. rills and ephemeral gullies, occurred on unprotected crop field. Erosion by concentrate flow was highly discontinuous within the catchment

  13. Runoff production in a small agricultural catchment in Lao PDR : influence of slope, land-use and observation scale.

    NASA Astrophysics Data System (ADS)

    Patin, J.; Ribolzi, O.; Mugler, C.; Valentin, C.; Mouche, E.

    2009-04-01

    We study the surface and sub-surface hydrology of a small agricultural catchment (60ha) located in the Luang Prabang province of Lao PDR. This catchment is representative of the rural mountainous south east Asia. It exhibits steep slopes (up to 100% and more) under a monsoon climate. After years of traditional slash and burn cultures, it is now under high land pressures due to population resettling and environment preservation policies. This evolution leads to rapid land-use changes such as shifting cultivation reduction or growing of teak forest instead of classical crops. This catchment is a benchmark site of the Managing Soil Erosion Consortium since 1998. The international consortium aims to understand the effects of agricultural changes on the catchment hydrology and soil erosion in south east Asia. The Huay Pano catchment is subdivided into small sub-catchments that are gauged and monitored. Differ- ent agricultural practices where tested along the years. At a smaller scale, plot of 1m2 are instrumented to follow runoff and detachment of soil under natural rainfall along the monsoon season. Our modeling work aims to develop a distributed hydrological model integrating experimental data at the different scales. One of the objective is to understand the impact of land-use, soil properties (slope, crust, etc) and rainfall (dry and wet seasons) on surface and subsurface flows. We present here modeling results of the runoff plot experiments (1m2 scale) performed from 2002 to 2007. The plots distribution among the catchment and over the years gives a good representativity of the different runoff responses. The role of crust, slope and land-use on runoff is examined. Finally we discuss how this plot scale will be integrated in a sub-catchment model, with a particular attention on the observed paradox: how to explain that runoff coefficients at the catchment scale are much slower than at the plot scale ?

  14. Storage as a Metric of Catchment Comparison

    USGS Publications Warehouse

    McNamara, J.P.; Tetzlaff, D.; Bishop, K.; Soulsby, C.; Seyfried, M.; Peters, N.E.; Aulenbach, Brent T.; Hooper, R.

    2011-01-01

    The volume of water stored within a catchment, and its partitioning among groundwater, soil moisture, snowpack, vegetation, and surface water are the variables that ultimately characterize the state of the hydrologic system. Accordingly, storage may provide useful metrics for catchment comparison. Unfortunately, measuring and predicting the amount of water present in a catchment is seldom done; tracking the dynamics of these stores is even rarer. Storage moderates fluxes and exerts critical controls on a wide range of hydrologic and biologic functions of a catchment. While understanding runoff generation and other processes by which catchments release water will always be central to hydrologic science, it is equally essential to understand how catchments retain water. We have initiated a catchment comparison exercise to begin assessing the value of viewing catchments from the storage perspective. The exercise is based on existing data from five watersheds, no common experimental design, and no integrated modelling efforts. Rather, storage was estimated independently for each site. This briefing presents some initial results of the exercise, poses questions about the definitions and importance of storage and the storage perspective, and suggests future directions for ongoing activities. ?? 2011 John Wiley & Sons, Ltd.

  15. Simulation of the reduction of runoff and sediment load resulting from the Gain for Green Program in the Jialingjiang catchment, upper region of the Yangtze River, China.

    PubMed

    Hayashi, Seiji; Murakami, Shogo; Xu, Kai-Qin; Watanabe, Masataka

    2015-02-01

    A distributed catchment hydrologic model (Hydrological Simulation Program--FORTRAN; HSPF) with improved sediment production processes was used to evaluate the effect of restoration of cultivated land to forest on the reduction of runoff and sediment load in the Jialingjiang basin, which forms part of the Yangtze River basin, China. The simulation results showed that restoration to forest reduced sediment production even in the case of minimum restoration at a threshold catchment slope of 25°, as advocated in the "Gain for Green Program " planned by the Chinese government, even though reduction of the peak flow rate in the river channel was small. The increase in forest area resulting from lowering of the threshold catchment slope reduced sediment production further. PMID:25463578

  16. Sediment dynamics during the rainy season in tropical highland catchments of central Mexico using fallout radionuclides

    NASA Astrophysics Data System (ADS)

    Evrard, Olivier; Némery, Julien; Gratiot, Nicolas; Duvert, Clément; Ayrault, Sophie; Lefèvre, Irène; Poulenard, Jérôme; Prat, Christian; Bonté, Philippe; Esteves, Michel

    2010-12-01

    Tropical regions are affected by intense soil erosion associated with deforestation, overgrazing, and cropping intensification. This land degradation leads to important on-site (e.g., decrease in soil fertility) and off-site (e.g., reservoir siltation and water pollution) impacts. This study determined the mean soil particle and sediment residence times in soils and rivers of three subcatchments (3-12 km 2) with contrasted land uses (i.e., cropland, forests, and rangelands) draining to a reservoir located in highlands of the transvolcanic Mexican belt. Calculations were based on rainfall amount and river discharges as well as on fallout radionuclide measurements (Be-7, Cs-137, and Pb-210) conducted on rainfall precipitated samples, soil sampled in the catchments, and suspended sediment collected by automatic samplers in the river during most storms recorded throughout the 2009 rainy season. Calculations using a radionuclide two-box balance model showed that the mean residence time of particles in soils ranged between 5000 ± 1500 and 23,300 ± 7000 years. In contrast, sediment residence time in rivers was much shorter, fluctuating between 50 ± 30 and 200 ± 70 days. The shortest mean residence times were measured in a hilly catchment dominated by cropland and rangelands, whereas they were the longest in an undulating catchment dominated by forests and cropland. Calculation of the Be-7/excess-Pb-210 in both rainfall and sediment allowed gaining insight on sediment dynamics throughout the rainy season. The first heavy storms of the year exported the bulk of the sediment stock accumulated in the river channel during the previous year. Then, during the rainy season, the two steeper catchments dominated by cropland and rangelands reacted strongly to rainfall. Sediment was indeed eroded and exported from both catchments during single heavy storms on several occasions in 2009. In contrast, the agro-forested catchment with gentler slopes exported sediment at a constant

  17. Collaborative knowledge in catchment research networks

    NASA Astrophysics Data System (ADS)

    Macleod, Christopher Kit

    2015-04-01

    There is a need to improve the production, sharing and use of collaborative knowledge of catchment systems through networks of researchers, policy makers and practitioners. This requires greater levels of systems based integrative research. In parallel to the growing realization that greater levels of collaborative knowledge in scientific research networks are required, a digital revolution has been taking place. This has been driven primarily by the emergence of distributed networks of computers and standards-based interoperability. The objective of this paper is to present the status and research needs for greater levels of systems based integrative research for the production, sharing and use of collaborative knowledge in catchment research networks. To enable increased levels of integrative research depends on development and application of digital technologies to improve collection, use and sharing of data and devise new knowledge infrastructures. This paper focuses on the requirements for catchment observatories that integrate existing and novel physical, social and digital networks of knowledge infrastructures. To support this focus, I present three leading international examples of collaborative networks of catchment researchers and their development of catchment observatories. In particular, the digital infrastructures they have developed to support collaborative knowledge in catchment research networks. These examples are from North America (NSF funded CUAHSI HIS) and from Europe (UK NERC funded EVOp and the German Helmholtz Association Centers funded TERENO/TEODOOR). These exemplars all supported advancing collaborative knowledge in catchment research networks through the development of catchment observatories. I will conclude by discussing the future research directions required for greater levels of production, sharing and use of collaborative knowledge in catchment research networks based on catchment systems science.

  18. Catchment-scale variation in the nitrate concentrations of groundwater seeps in the Catskill Mountains, New York, U.S.A.

    USGS Publications Warehouse

    West, A.J.; Findlay, S.E.G.; Burns, Douglas A.; Weathers, K.C.; Lovett, Gary M.

    2001-01-01

    Forested headwater streams in the Catskill Mountains of New York show significant among-catchment variability in mean annual nitrate (NO3-) concentrations. Large contributions from deep groundwater with high NO3- concentrations have been invoked to explain high NO3- concentrations in stream water during the growing season. To determine whether variable contributions of groundwater could explain among-catchment differences in streamwater, we measured NO3- concentrations in 58 groundwater seeps distributed across six catchments known to have different annual average streamwater concentrations. Seeps were identified based on release from bedrock fractures and bedding planes and had consistently lower temperatures than adjacent streamwaters. Nitrate concentrations in seeps ranged from near detection limits (0.005 mg NO3--N/L) to 0.75 mg NO3--N/L. Within individual catchments, groundwater residence time does not seem to strongly affect NO3- concentrations because in three out of four catchments there were non-significant correlations between seep silica (SiO2) concentrations, a proxy for residence time, and seep NO3- concentrations. Across catchments, there was a significant but weak negative relationship between NO3- and SiO2 concentrations. The large range in NO3- concentrations of seeps across catchments suggests: 1) the principal process generating among-catchment differences in streamwater NO3- concentrations must influence water before it enters the groundwater flow system and 2) this process must act at large spatial scales because among-catchment variability is much greater than intra-catchment variability. Differences in the quantity of groundwater contribution to stream baseflow are not sufficient to account for differences in streamwater NO3- concentrations among catchments in the Catskill Mountains.

  19. Data mining methods for predicting event runoff coefficients in ungauged basins using static and dynamic catchment characteristics

    NASA Astrophysics Data System (ADS)

    Loritz, Ralf; Weiler, Markus; Seibert, Simon

    2015-04-01

    Transferring hydrological information into ungauged basin by regionalisation approaches is an ongoing field of research. Usually regionalisation techniques use physical landscape descriptors to transfer either model parameters or hydrological characteristics from a catchment to another. A common problem of these approaches is the high degree of uncertainty associated to their results. One reason is that often solely static (structural) catchment characteristics such as catchment area, physiographic properties or land use data are used for regionalisation. However, it is well known that the hydrological response of a 'natural' system is a complex and a non-linear interaction of its structure, state and forcing. Here it is important to note, that only structure is a static property. State and forcing are highly dynamic when considering the temporal and spatial scale of a rainfall-runoff event. To overcome the limitations associated with 'static' regionalisation techniques we propose a regionalisation technique for event runoff coefficients combining static and dynamic catchment properties. The approach is based on the two data mining algorithms 'random forests' and 'quantile regression forests'. The static catchment characteristics include standard variables such as physiographic properties, land cover and soil data. The dynamic variables include event based properties of the forcing (i.e. rainfall amount, intensity,...) and proxies for the initial state of the catchment (i.e. initial soil moisture). Together with the runoff coefficient these quantities were extracted form hydro-meteorological time series (precipitation, discharge and soil moisture) using an automated rainfall-runoff event detection technique. We tested our method using a set of 60 meso-scale catchments (3.1 to 205,6 km2, covering a range of different geologies and land uses) from Southwest Germany. We randomly separated the catchments in two groups. The first group (30 donor catchments) was used to

  20. Exploring the long-term response of undisturbed Mediterranean catchments to changes in atmospheric inputs through time series analysis.

    PubMed

    Bernal, S; Belillas, C; Ibáñez, J J; Àvila, A

    2013-08-01

    The aim of this study was to gain insights on the potential hydrological and biogeochemical mechanisms controlling the response of two nested Mediterranean catchments to long-term changes in atmospheric inorganic nitrogen and sulphate deposition. One catchment was steep and fully forested (TM9, 5.9 ha) and the other one had gentler slopes and heathlands in the upper part while side slopes were steep and forested (TM0, 205 ha). Both catchments were highly responsive to the 45% decline in sulphate concentration measured in atmospheric deposition during the 1980s and 1990s, with stream concentrations decreasing by 1.4 to 3.4 μeq L(-1) y(-1). Long-term changes in inorganic nitrogen in both, atmospheric deposition and stream water were small compared to sulphate. The quick response to changes in atmospheric inputs could be explained by the small residence time of water (4-5 months) in these catchments (inferred from chloride time series variance analysis), which was attributed to steep slopes and the role of macropore flow bypassing the soil matrix during wet periods. The estimated residence time for sulphate (1.5-3 months) was substantially lower than for chloride suggesting unaccounted sources of sulphate (i.e., dry deposition, or depletion of soil adsorbed sulphate). In both catchments, inorganic nitrogen concentration in stream water was strongly damped compared to precipitation and its residence time was of the order of decades, indicating that this essential nutrient was strongly retained in these catchments. Inorganic nitrogen concentration tended to be higher at TM0 than at TM9 which was attributed to the presence of nitrogen fixing species in the heathlands. Our results indicate that these Mediterranean catchments react rapidly to environmental changes, which make them especially vulnerable to changes in atmospheric deposition.

  1. Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method.

    PubMed

    Müller-Herbst, Stefanie; Wüstner, Stefanie; Kabisch, Jan; Pichner, Rohtraud; Scherer, Siegfried

    2016-06-01

    Sodium nitrite (NaNO2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. In the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of Listeria monocytogenes in short-ripened spreadable raw sausages. Furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like temperature, oxygen availability, pH, NaCl concentration, and absence or presence of NaNO2. Data based on 300 growth conditions revealed that the inhibitory effect of nitrite was most prominent in combination with acidification, a combination that is also achieved during short-ripened spreadable raw sausage production. At pH6.0 and below, L. monocytogenes was unable to replicate in the presence of 200mg/l NaNO2. During the adaptation of L. monocytogenes to acidified nitrite stress (pH6.0, 200mg/l NaNO2) in comparison to acid exposure only (pH6.0, 0mg/l NaNO2), a massive transcriptional adaptation was observed using microarray analyses. In total, 202 genes were up-regulated and 204 genes were down-regulated. In accordance with growth inhibition, a down-regulation of genes encoding for proteins which are involved in central cellular processes, like cell wall/membrane/envelope biogenesis, translation and ribosomal structure and biogenesis, transcription, and replication, recombination and repair, was observed. Among the up-regulated genes the most prominent group belonged to poorly characterized genes. A considerable fraction of the up-regulated genes has been shown previously to be up-regulated intracellularly in macrophages, after exposure to acid shock or to be part of the SigB regulon. These data indicate that the adaptation to acidified nitrite partly overlaps with the adaptation to stress conditions being present during host colonization. PMID:27017279

  2. Mercury speciation, fluxes, and fate in the volcanically acidified fluids of Copahue volcano, Argentina

    NASA Astrophysics Data System (ADS)

    Kading, T.; Varekamp, J. C.; Andersson, M.; Balcom, P.; Mason, R. P.

    2010-12-01

    The behavior of mercury in volcanic acid springs and acidified rivers is poorly known, despite the potential impact this vector of contamination has on local surface and ground water quality. Mercury was measured in a volcanically acidified river system (pH<1 - 3), the Rio Agrio in the Neuquen province of Argentina, which discharges into a large glacial lake (Lake Caviahue, pH 2.2-3.0). The Hg concentration ranged from 2 - 600 pM throughout the fluvial system. Mercury in the hot, hyperacidic source fluids was dominated by dissolved ionic species, with only 2% of total mercury as dissolved elemental mercury, and 11% being particulate bound. The Hg flux from the volcano, determined from river water flux measurements and Hg concentrations, was modest and varied between the 3/2008 and 3/2009 sampling campaigns resp. from 0.7 to 1.1 moles/year. The Hg:S ratio of the acid fluids was ~10-8, several orders of magnitude lower than that typically found in volcanic plumes and fumaroles. The small Hg flux and low Hg:S values suggest that the system is either inherently Hg-poor or has lost Hg through vapor loss deeper in the hydrothermal system. Support for the latter comes from high Hg concentrations in geothermal vents and mudpots on the flank of the mountain (24 - 55 ppm Hg). Mercury concentrations decreased conservatively downstream in the river as based on Hg/Cl and Hg/SO4. Non-conservative depletion occurs in the less acidic Lake Caviahue, suggesting that mercury is removed from the water column by sorption to organic matter or other phases. Mercury analyses of a short lake sediment core confirm this (Hg = 0.01 to 0.70 ppm). No evidence was found for preferential uptake of mercury by jarosite, schwertmannite, or goethite, although the latter two phases precipitate in the most distal and Hg-depleted section of the fluvial system.

  3. Sequestration of organic cations by acidified hepatic endocytic vesicles and implications for biliary excretion.

    PubMed

    Van Dyke, R W; Faber, E D; Meijer, D K

    1992-04-01

    A number of cationic amine drugs that are taken up by liver and excreted into bile may accumulate in acidified intracellular organelles such as lysosomes and endosomes. These studies were undertaken to assess directly the uptake and accumulation of three types of model organic cationic amines by endocytic vesicles, and the role of vesicle acidification in this process. Uptake of tubocurarine (TC), vecuronium and tributylmethylammonium (TBuMA) by purified rat liver multivesicular bodies (MVB) (prelysosomal endocytic vesicles) was dependent upon MgATP, time and drug concentration. After 60 min, 52 to 81% of MVB cation content was dependent upon vesicle acidification (due to an electrogenic proton pump), but not upon an interior positive vesicle membrane potential. Nineteen to 42% of MVB cation content appeared due to binding to MVB membranes or to internal lipoproteins. Vesicle-to-medium ATP-dependent apparent concentration ratios for these three cations were 3.3 to 51. MVB uptake of these cations resembled uptake of methylamine, a tertiary amine known to distribute across organellar membranes according to pH gradients. By contrast, MVB uptake of the lipophilic quaternary amine methyldeptropine was not dependent upon MgATP or on development of MVB pH or membrane potential gradients. In further studies, TC, vecuronium and TBuMA were rapidly taken up by the isolated perfused rat liver and excreted in bile. Exposure to 250 mciroM primaquin (which partially alkalinized acidic endosomes and lysosomes) reduced accumulation of [3H]vecuronium in a lysosomal fraction by 23%, decreased perfusate disappearance of TC and TBuMA, but not of vecuronium, and decreased biliary appearance of all three cations. These studies suggest that acidified intracellular organelles sequester certain organic cationic drugs, possibly via a drug/proton antiporter, and/or diffusion followed by intravesicular protonation and trapping of tertiary amines. However, attempts at partial displacement of

  4. Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method.

    PubMed

    Müller-Herbst, Stefanie; Wüstner, Stefanie; Kabisch, Jan; Pichner, Rohtraud; Scherer, Siegfried

    2016-06-01

    Sodium nitrite (NaNO2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. In the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of Listeria monocytogenes in short-ripened spreadable raw sausages. Furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like temperature, oxygen availability, pH, NaCl concentration, and absence or presence of NaNO2. Data based on 300 growth conditions revealed that the inhibitory effect of nitrite was most prominent in combination with acidification, a combination that is also achieved during short-ripened spreadable raw sausage production. At pH6.0 and below, L. monocytogenes was unable to replicate in the presence of 200mg/l NaNO2. During the adaptation of L. monocytogenes to acidified nitrite stress (pH6.0, 200mg/l NaNO2) in comparison to acid exposure only (pH6.0, 0mg/l NaNO2), a massive transcriptional adaptation was observed using microarray analyses. In total, 202 genes were up-regulated and 204 genes were down-regulated. In accordance with growth inhibition, a down-regulation of genes encoding for proteins which are involved in central cellular processes, like cell wall/membrane/envelope biogenesis, translation and ribosomal structure and biogenesis, transcription, and replication, recombination and repair, was observed. Among the up-regulated genes the most prominent group belonged to poorly characterized genes. A considerable fraction of the up-regulated genes has been shown previously to be up-regulated intracellularly in macrophages, after exposure to acid shock or to be part of the SigB regulon. These data indicate that the adaptation to acidified nitrite partly overlaps with the adaptation to stress conditions being present during host colonization.

  5. DOC quantity and quality in northeastern USA catchments

    NASA Astrophysics Data System (ADS)

    Shanley, J. B.; Sebestyen, S. D.; Aiken, G.; Pellerin, B. A.

    2011-12-01

    At the Sleepers River Research Watershed in Vermont we have studied interactions of dissolved organic carbon (DOC) cycling and hydrological processes for nearly 20 years to determine how and when DOC is transported through the landscape. Stream DOC concentration in this cool temperate forested catchment varies from ~1 to ~15 mg L-1 and is transport-limited; concentrations increase with increasing flow, even under the wettest conditions, suggesting shifting but non-depletable sources. Specific UV absorbance (SUVA) also increases consistently with flow. Source strength does vary seasonally, however, evidenced by higher DOC for a given flow during autumn leaf fall relative to spring snowmelt. Recent high-frequency optical sensor measurements have revealed fine-scale structure in the temporal DOC pattern not possible from discrete sampling. We observe a consistent counterclockwise hysteresis and diurnal cycles with seasonally variable amplitude. In this presentation we infer DOC sources and processes through analysis of antecedent moisture conditions and concurrent variations in nitrate, dissolved organic nitrogen, and SUVA. With sensors and sampling in place at several other research catchments, we are investigating the similarity of patterns across the northeastern USA.

  6. Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

    PubMed Central

    Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

    2014-01-01

    Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to

  7. Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America.

    PubMed

    Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

    2014-10-01

    Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period - a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI - high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to

  8. DOM in stream water and soil solution in two small, bordering catchments in central Sweden

    NASA Astrophysics Data System (ADS)

    Norström, Sara H.; Bylund, Dan

    2013-04-01

    Seasonal variations in dissolved organic matter (DOM) and the influence of wood ash application on DOM were studied in two first order streams draining two small, bordering forested catchments. The catchments, 40 and 50 h respectively, were situated in Bispgården (63°07N, 16°70E), central Sweden with forest consisting of mainly 50 to 80 year-old Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). Seasonal variations in the stream water were measured during 2003-2007, and wood ash was applied in one of the catchments in the fall of 2004. In addition to stream water samples, sampling of soil solution in the riparian zone was made in one of the catchments during 2003-2006. The quantity of DOM differed between the streams, but the seasonal patterns for the two streams were correlated during 2003 and 2004. After wood ash treatment, dissolved organic carbon (DOC) increased significantly in the stream draining the treated catchment. 17 different low molecular mass organic acids (LMMOAs) were measured in the stream water during the whole study period. The most abundant LMMOAs were oxalic- and lactic acid, of which peak concentrations of oxalic acid coincided with those of DOC, while no such relation between the concentrations of DOC and lactic acid could be seen in either of the streams. Some of the most common acids in the soil solution, shikimic acid, citric acid and malic acid were rarely found in the stream water and only then in very low concentrations, thus appearing not to have made the transition from soil to stream water in the same manner as oxalic acid. The wood ash application did not affect the total LMMOA concentration and there was no difference during the investigated period. Of the 17 analysed LMMOAs, only malonic acid appeared affected by wood ash application, with a significant increase during both 2005 and 2006.

  9. A model for assessing water quality risk in catchments prone to wildfire

    NASA Astrophysics Data System (ADS)

    Langhans, Christoph; Smith, Hugh G.; Chong, Derek M. O.; Nyman, Petter; Lane, Patrick N. J.; Sheridan, Gary J.

    2016-03-01

    Post-fire debris flows can have erosion rates up to three orders of magnitude higher than background rates. They are major sources of fine suspended sediment, which is critical to the safety of water supply from forested catchments. Fire can cover parts or all of these large catchments and burn severity is often heterogeneous. The probability of spatial and temporal overlap of fire disturbance and rainfall events, and the susceptibility of hillslopes to severe erosion determine the risk to water quality. Here we present a model to calculate recurrence intervals of high magnitude sediment delivery from runoff-generated debris flows to a reservoir in a large catchment (>100 km2) accounting for heterogeneous burn conditions. Debris flow initiation was modelled with indicators of surface runoff and soil surface erodibility. Debris flow volume was calculated with an empirical model, and fine sediment delivery was calculated using simple, expert-based assumptions. In a Monte-Carlo simulation, wildfire was modelled with a fire spread model using historic data on weather and ignition probabilities for a forested catchment in central Victoria, Australia. Multiple high intensity storms covering the study catchment were simulated using Intensity-Frequency-Duration relationships, and the runoff indicator calculated with a runoff model for hillslopes. A sensitivity analysis showed that fine sediment is most sensitive to variables related to the texture of the source material, debris flow volume estimation, and the proportion of fine sediment transported to the reservoir. As a measure of indirect validation, denudation rates of 4.6-28.5 mm ka-1 were estimated and compared well to other studies in the region. From the results it was extrapolated that in the absence of fire management intervention the critical sediment concentrations in the studied reservoir could be exceeded in intervals of 18-124 years.

  10. Doing hydrology backwards in tropical humid catchments

    NASA Astrophysics Data System (ADS)

    Real Rangel, R.; Brena-Naranjo, J. A.; Pedrozo-Acuña, A.

    2015-12-01

    Top-down approaches in hydrology offer the possibility to predict water fluxes at the catchment scale based on the interpretation of the observed hydrological response at the catchment itself. Doing hydrology backwards (inferring precipitation and evapotranspiration rates at the catchment scale from streamflow measurements, see Kirchner (2009)) can be a useful methodology for estimating water fluxes at the catchment and regional scales. Previous studies using this inverse modeling approach have been performed in regions (UK, Switzerland, France, Eastern US) where energy-limited (in winter and early spring) and water-limited conditions (in summer) prevail during a large period of the year. However, such approach has not been tested in regions characterized by a quasi-constant supply of water and energy (e.g. humid tropics). The objective of this work is to infer annual rates of precipitation and evapotranspiration over the last decade in 10 catchments located in Mexico's tropical humid regions. Hourly discharge measurements during recession periods were analyzed and parameters for the nonlinear storage-discharge relationship of each catchment were derived. Results showed large variability in both catchment-scale precipitation and evapotranspiration rates among the selected study sites. Finally, a comparison was done between such estimates and those obtained from remotely-sensed data (TRMM for precipitation and MOD16 for evapotranspiration).

  11. Catchment water storage: Models vs Measurements

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary

    2016-04-01

    Recent years have seen a great deal of progress in development of hydrological models that can simulate both the dynamic streamflow response and the hydrochemical flux response of a catchment. In general terms, streamflow response is driven by water deficit in the catchment, whereas hydrochemical response is driven by water storage. Therefore, models that can simultaneously predict both responses must succeed in representing these two related, but different, quantities. This presentation will consider how much information we can gain from field studies to quantify the joint deficit/storage state of a catchment. In particular, examples from two New Zealand experimental catchments in lowland and high country locations will be used to link typical measurements available with the information required by hydrological - hydrochemical models. I will then use the example catchments to assess how well the structure of a typical hydrological-hydrochemical model is supported by field measurements. In particular, can we quantify catchment storage and link this to flow response? Can we incorporate our knowledge of plant water use into such a model, including timing and depth of water withdrawn by the plant? What can field measurements tell us about spatial variability in hydrological-hydrochemical response and can this be represented in the model? I will conclude by discussing what we can learn from field data about the major challenges ahead in catchment storage modelling.

  12. Using biomarkers as fingerprint properties to identify sediment sources in a small catchment.

    PubMed

    Chen, Fangxin; Fang, Nufang; Shi, Zhihua

    2016-07-01

    Traditional fingerprinting methods are limited in their ability to identify soil erosion sources where geologic variations are small or where different land uses span geological boundaries. In this study, a new biomarker for fingerprinting, specifically, n-alkanes, was used in a small catchment to identify sediment sources. The n-alkanes were based on land uses, could provide vegetation information, and were relatively resistant to diagenetic modifications and decomposition. This study used a composite fingerprinting method that was based on two types of fingerprint factors (27 biomarker properties and 45 geochemical properties) with 60 source samples (i.e., gully, grassland, forest, and cropland) and nine soil profiles. Genetic algorithm (GA) optimization has been deployed to find the optimal source contribution to sediments. The biomarker results demonstrated that young forest is the main sediment source in this catchment, contributing 50.5%, whereas cropland, grassland and gully contributed 25.6%, 14.4% and 9.5%, respectively; the geochemistry results were similar to the biomarkers. The forest and grassland contributions gradually increased from upstream to downstream, and the sediment contributions of cropland gradually decreased in the direction of the runoff pathway at the check dam. In a comparison of biomarker and geochemical fingerprinting data, the latter may have overestimated the forest inputs to the catchment sediment yields because of a mixed land use history (i.e., forest and grassland). The geochemical fingerprint approach limits its ability to fully discriminate sources based on land management regimes, but the biomarker (individual n-alkanes) displayed the potential to discriminate between a greater number and different types of sediment sources and to provide greater detail regarding sediment sources.

  13. Water Catchment and Storage Monitoring

    NASA Astrophysics Data System (ADS)

    Bruenig, Michael; Dunbabin, Matt; Moore, Darren

    2010-05-01

    Sensors and Sensor Networks technologies provide the means for comprehensive understanding of natural processes in the environment by radically increasing the availability of empirical data about the natural world. This step change is achieved through a dramatic reduction in the cost of data acquisition and many orders of magnitude increase in the spatial and temporal granularity of measurements. Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) is undertaking a strategic research program developing wireless sensor network technology for environmental monitoring. As part of this research initiative, we are engaging with government agencies to densely monitor water catchments and storages, thereby enhancing understanding of the environmental processes that affect water quality. In the Gold Coast hinterland in Queensland, Australia, we are building sensor networks to monitor restoration of rainforest within the catchment, and to monitor methane flux release and water quality in the water storages. This poster will present our ongoing work in this region of eastern Australia. The Springbrook plateau in the Gold Coast hinterland lies within a World Heritage listed area, has uniquely high rainfall, hosts a wide range of environmental gradients, and forms part of the catchment for Gold Coast's water storages. Parts of the plateau are being restored from agricultural grassland to native rainforest vegetation. Since April 2008, we have had a 10-node, multi-hop sensor network deployed there to monitor microclimate variables. This network will be expanded to 50-nodes in February 2010, and to around 200-nodes and 1000 sensors by mid-2011, spread over an area of approximately 0.8 square kilometers. The extremely dense microclimate sensing will enhance knowledge of the environmental factors that enhance or inhibit the regeneration of native rainforest. The final network will also include nodes with acoustic and image sensing capability for

  14. Long-term changes of water and chemical budgets after clear-cutting of a small headwater catchment in Japan

    NASA Astrophysics Data System (ADS)

    Oda, T.; Egusa, T.; Ohte, N.; Takeda, M.; Suzuki, M.

    2014-12-01

    To understand the mechanisms of hydrological and biogeochemical processes of forest ecosystems, long term monitoring of changes in water and chemical budgets after forest disturbance is important. Previous studies have generally focused on changes in stream runoff and water chemistry. However, the long term changes in forest-canopy ecosystems such as rainfall partitioning and the chemical budget of the canopy have not been sufficiently considered. Therefore, the objectives of this study were to evaluate the long-term changes of input and output budgets of water and chemistry after clear-cutting of forest catchment. The study was conducted in a pair of small headwater catchments, one of which was clear-cut in 1999 and then planted with the same species in 2000; the other served as a control. After forest cutting, annual runoff increased 200-300 mm/yr and the higher runoff still remained 14 years later. The interception ratio in the clear-cut catchment was less than 10% of precipitation, whereas that in the control catchment was 20-24% of precipitation. Interception rate was still lower in the young forest compared with the mature forest, despite similar transpiration rate. With regard to chemistry, Cl- and SO42- concentrations in stream water decreased after cutting and remained lower 14 years later. On the other hand, NO3- concentration increased and finally returned to its pre-cut level. The atmospheric deposition inputs, such as those of Cl-, Na+, and SO42-, remained lower in the clear-cut catchment than in the control. On the other hand, input of K+, Mg2+, and Ca2+ originating from canopy leaching became significantly higher in the clear-cut catchment compared with those in the control. These results suggest that not only the biological processes such as water and chemical uptake by plants, but also changes in canopy physical processes such as canopy interception and chemical scavenging, affected the long-term response of stream runoff and chemistry following

  15. Flushing of distal hillslopes as an alternative source of stream dissolved organic carbon in a headwater catchment

    USGS Publications Warehouse

    Gannon, John P; Bailey, Scott W.; McGuire, Kevin J.; Shanley, James B.

    2015-01-01

    We investigated potential source areas of dissolved organic carbon (DOC) in headwater streams by examining DOC concentrations in lysimeter, shallow well, and stream water samples from a reference catchment at the Hubbard Brook Experimental Forest. These observations were then compared to high-frequency temporal variations in fluorescent dissolved organic matter (FDOM) at the catchment outlet and the predicted spatial extent of shallow groundwater in soils throughout the catchment. While near-stream soils are generally considered a DOC source in forested catchments, DOC concentrations in near-stream groundwater were low (mean = 2.4 mg/L, standard error = 0.6 mg/L), less than hillslope groundwater farther from the channel (mean = 5.7 mg/L, standard error = 0.4 mg/L). Furthermore, water tables in near-stream soils did not rise into the carbon-rich upper B or O horizons even during events. In contrast, soils below bedrock outcrops near channel heads where lateral soil formation processes dominate had much higher DOC concentrations. Soils immediately downslope of bedrock areas had thick eluvial horizons indicative of leaching of organic materials, Fe, and Al and had similarly high DOC concentrations in groundwater (mean = 14.5 mg/L, standard error = 0.8 mg/L). Flow from bedrock outcrops partially covered by organic soil horizons produced the highest groundwater DOC concentrations (mean = 20.0 mg/L, standard error = 4.6 mg/L) measured in the catchment. Correspondingly, stream water in channel heads sourced in part by shallow soils and bedrock outcrops had the highest stream DOC concentrations measured in the catchment. Variation in FDOM concentrations at the catchment outlet followed water table fluctuations in shallow to bedrock soils near channel heads. We show that shallow hillslope soils receiving runoff from organic matter-covered bedrock outcrops may be a major source of DOC in headwater catchments in forested mountainous regions

  16. Effects of distributed and centralized stormwater best management practices and land cover on urban stream hydrology at the catchment scale

    USGS Publications Warehouse

    Loperfido, John V.; Noe, Gregory B.; Jarnagin, S. Taylor; Hogan, Dianna M.

    2014-01-01

    Urban stormwater runoff remains an important issue that causes local and regional-scale water quantity and quality issues. Stormwater best management practices (BMPs) have been widely used to mitigate runoff issues, traditionally in a centralized manner; however, problems associated with urban hydrology have remained. An emerging trend is implementation of BMPs in a distributed manner (multi-BMP treatment trains located on the landscape and integrated with urban design), but little catchment-scale performance of these systems have been reported to date. Here, stream hydrologic data (March, 2011–September, 2012) are evaluated in four catchments located in the Chesapeake Bay watershed: one utilizing distributed stormwater BMPs, two utilizing centralized stormwater BMPs, and a forested catchment serving as a reference. Among urban catchments with similar land cover, geology and BMP design standards (i.e. 100-year event), but contrasting placement of stormwater BMPs, distributed BMPs resulted in: significantly greater estimated baseflow, a higher minimum precipitation threshold for stream response and maximum discharge increases, better maximum discharge control for small precipitation events, and reduced runoff volume during an extreme (1000-year) precipitation event compared to centralized BMPs. For all catchments, greater forest land cover and less impervious cover appeared to be more important drivers than stormwater BMP spatial pattern, and caused lower total, stormflow, and baseflow runoff volume; lower maximum discharge during typical precipitation events; and lower runoff volume during an extreme precipitation event. Analysis of hydrologic field data in this study suggests that both the spatial distribution of stormwater BMPs and land cover are important for management of urban stormwater runoff. In particular, catchment-wide application of distributed BMPs improved stream hydrology compared to centralized BMPs, but not enough to fully replicate forested

  17. Effects of distributed and centralized stormwater best management practices and land cover on urban stream hydrology at the catchment scale

    NASA Astrophysics Data System (ADS)

    Loperfido, J. V.; Noe, Gregory B.; Jarnagin, S. Taylor; Hogan, Dianna M.

    2014-11-01

    Urban stormwater runoff remains an important issue that causes local and regional-scale water quantity and quality issues. Stormwater best management practices (BMPs) have been widely used to mitigate runoff issues, traditionally in a centralized manner; however, problems associated with urban hydrology have remained. An emerging trend is implementation of BMPs in a distributed manner (multi-BMP treatment trains located on the landscape and integrated with urban design), but little catchment-scale performance of these systems have been reported to date. Here, stream hydrologic data (March, 2011-September, 2012) are evaluated in four catchments located in the Chesapeake Bay watershed: one utilizing distributed stormwater BMPs, two utilizing centralized stormwater BMPs, and a forested catchment serving as a reference. Among urban catchments with similar land cover, geology and BMP design standards (i.e. 100-year event), but contrasting placement of stormwater BMPs, distributed BMPs resulted in: significantly greater estimated baseflow, a higher minimum precipitation threshold for stream response and maximum discharge increases, better maximum discharge control for small precipitation events, and reduced runoff volume during an extreme (1000-year) precipitation event compared to centralized BMPs. For all catchments, greater forest land cover and less impervious cover appeared to be more important drivers than stormwater BMP spatial pattern, and caused lower total, stormflow, and baseflow runoff volume; lower maximum discharge during typical precipitation events; and lower runoff volume during an extreme precipitation event. Analysis of hydrologic field data in this study suggests that both the spatial distribution of stormwater BMPs and land cover are important for management of urban stormwater runoff. In particular, catchment-wide application of distributed BMPs improved stream hydrology compared to centralized BMPs, but not enough to fully replicate forested

  18. Identifying dominant controls on hydrologic parameter transfer from gauged to ungauged catchments: a comparative hydrology approach

    USGS Publications Warehouse

    Singh, R.; Archfield, S.A.; Wagener, T.

    2014-01-01

    Daily streamflow information is critical for solving various hydrologic problems, though observations of continuous streamflow for model calibration are available at only a small fraction of the world’s rivers. One approach to estimate daily streamflow at an ungauged location is to transfer rainfall–runoff model parameters calibrated at a gauged (donor) catchment to an ungauged (receiver) catchment of interest. Central to this approach is the selection of a hydrologically similar donor. No single metric or set of metrics of hydrologic similarity have been demonstrated to consistently select a suitable donor catchment. We design an experiment to diagnose the dominant controls on successful hydrologic model parameter transfer. We calibrate a lumped rainfall–runoff model to 83 stream gauges across the United States. All locations are USGS reference gauges with minimal human influence. Parameter sets from the calibrated models are then transferred to each of the other catchments and the performance of the transferred parameters is assessed. This transfer experiment is carried out both at the scale of the entire US and then for six geographic regions. We use classification and regression tree (CART) analysis to determine the relationship between catchment similarity and performance of transferred parameters. Similarity is defined using physical/climatic catchment characteristics, as well as streamflow response characteristics (signatures such as baseflow index and runoff ratio). Across the entire US, successful parameter transfer is governed by similarity in elevation and climate, and high similarity in streamflow signatures. Controls vary for different geographic regions though. Geology followed by drainage, topography and climate constitute the dominant similarity metrics in forested eastern mountains and plateaus, whereas agricultural land use relates most strongly with successful parameter transfer in the humid plains.

  19. Topographical and Hydrological Influences on the Spatial Distribution of Mercury at the Catchment Scale

    NASA Astrophysics Data System (ADS)

    Gunda, T.; Converse, A.; Riscassi, A.; Scanlon, T. M.

    2009-12-01

    Inorganic forms of mercury (Hg) can be converted through natural processes into methylmercury, a highly potent neurotoxin that can bioaccumulate in food chains and pose a risk to human health. Although Hg can enter aquatic environments through direct deposition, the predominant source tends to be mobilized Hg deposited in nearby terrestrial systems. Therefore, understanding the complex intermediate Hg cycling in vegetation and soils is crucial to predicting its presence in water bodies and potential for bioaccumulation. While prior studies have revealed dependence of Hg distribution on forest types and soil characteristics, less attention has been given to the role of aspect and hydrological factors on Hg deposition and consequent spatial distribution within catchments. My research addresses this by conducting a litterfall and soil sampling study to assess Hg spatial distribution within two paired catchments: northwest-facing North Fork Dry Run and southeast-facing Hannah Run. Litterfall and soil samples collected through a random stratified sampling process were analyzed for total Hg concentrations using a Cold Vapor Atomic Fluorescence Spectrometry. An analysis of variance conducted on leaf litter and soil Hg concentrations revealed that: (1) Hg accumulation in soils was significantly greater in the northwest-facing catchment than in the south-east facing catchment, while Hg accumulation in leaves was not found to differ, and (2) within each catchment the likelihood of saturation was not found to play a significant role in governing Hg accumulation in soils. Higher Hg levels in the soils of North Forth Dry Run could be attributable to predominant wind direction from sources of Hg (i.e., coal-burning power plants). Within catchments, lack of appreciable Hg deposition resulted in statistically insignificant variation amongst topographic index classes. The results of this study reveal the potential implications of mountainous terrains in distributing Hg arising from

  20. Hydrologic Transit Times in Tropical Montane Watersheds: Catchment Scale and Landscape Influences

    NASA Astrophysics Data System (ADS)

    Munoz Villers, L. E.; Geissert Kientz, D. R.; Holwerda, F.; McDonnell, J.

    2015-12-01

    Stream water mean transit time (MTT) is a fundamental hydrologic parameter that integrates the distribution of sources, flow paths and storages present in catchments. However, in the tropics little work has been carried out on MTT, despite its usefulness for providing important information about watershed hydrological functioning at different spatial scales in (largely) ungauged basins. In particular, very few studies have quantified stream MTTs and related to catchment characteristics in tropical montane regions. Here we examined topographic, land use/cover and soil hydraulic controls on baseflow MTT for nested watersheds (0.1-34 km2) within a humid mountainous region, underlain by volcanic soil (Andisols) in central Veracruz (eastern Mexico). To estimate MTTs, we used a 2 year record of bi-weekly isotopic composition of precipitation and stream baseflow data. Land use/cover and topographic parameters were derived from GIS analysis. Soil profile hydraulic properties and permeability at the soil-bedrock interface were obtained from intensive field measurements and laboratory analysis. Estimates of baseflow MTT ranged between 1.2 and 2.7 years across the 12 study catchments. Major differences in MTTs were found at the small (0.1-1.5 km2) and at the large scales (14-34 km2), related mostly to catchment slope and morphology and, to much lesser extent, to land cover. Interestingly, longest stream MTTs were found in the cloud forest headwater catchments. Overall, MTTs were mainly controlled by depth to bedrock associated with topography, and permeability at the soil-bedrock interface. Mid and ridge hillslope positions appeared to be the main contributing areas for catchment recharge and runoff. The present study is the first step towards to understand the hydrology and subsurface processes across scales in this tropical environment, with the aim to support decisions for local and regional management water supply under increasing land use and climate change pressures.

  1. Identifying dominant controls on hydrologic parameter transfer from gauged to ungauged catchments - A comparative hydrology approach

    NASA Astrophysics Data System (ADS)

    Singh, R.; Archfield, S. A.; Wagener, T.

    2014-09-01

    Daily streamflow information is critical for solving various hydrologic problems, though observations of continuous streamflow for model calibration are available at only a small fraction of the world's rivers. One approach to estimate daily streamflow at an ungauged location is to transfer rainfall-runoff model parameters calibrated at a gauged (donor) catchment to an ungauged (receiver) catchment of interest. Central to this approach is the selection of a hydrologically similar donor. No single metric or set of metrics of hydrologic similarity have been demonstrated to consistently select a suitable donor catchment. We design an experiment to diagnose the dominant controls on successful hydrologic model parameter transfer. We calibrate a lumped rainfall-runoff model to 83 stream gauges across the United States. All locations are USGS reference gauges with minimal human influence. Parameter sets from the calibrated models are then transferred to each of the other catchments and the performance of the transferred parameters is assessed. This transfer experiment is carried out both at the scale of the entire US and then for six geographic regions. We use classification and regression tree (CART) analysis to determine the relationship between catchment similarity and performance of transferred parameters. Similarity is defined using physical/climatic catchment characteristics, as well as streamflow response characteristics (signatures such as baseflow index and runoff ratio). Across the entire US, successful parameter transfer is governed by similarity in elevation and climate, and high similarity in streamflow signatures. Controls vary for different geographic regions though. Geology followed by drainage, topography and climate constitute the dominant similarity metrics in forested eastern mountains and plateaus, whereas agricultural land use relates most strongly with successful parameter transfer in the humid plains.

  2. Juvenile Antarctic rockcod (Trematomus bernacchii) are physiologically robust to CO2-acidified seawater.

    PubMed

    Davis, Brittany E; Miller, Nathan A; Flynn, Erin E; Todgham, Anne E

    2016-04-15

    To date, numerous studies have shown negative impacts of CO2-acidified seawater (i.e. ocean acidification, OA) on marine organisms, including calcifying invertebrates and fishes; however, limited research has been conducted on the physiological effects of OA on polar fishes and even less on the impact of OA on early developmental stages of polar fishes. We evaluated aspects of aerobic metabolism and cardiorespiratory physiology of juvenile emerald rockcod, ITALIC! Trematomus bernacchii, an abundant fish in the Ross Sea, Antarctica, to elevated partial pressure of carbon dioxide ( ITALIC! PCO2 ) [420 (ambient), 650 (moderate) and 1050 (high) μatm ITALIC! PCO2 ] over a 1 month period. We examined cardiorespiratory physiology, including heart rate, stroke volume, cardiac output and ventilation rate, whole organism metabolism via oxygen consumption rate and sub-organismal aerobic capacity by citrate synthase enzyme activity. Juvenile fish showed an increase in ventilation rate under high ITALIC! PCO2 compared with ambient ITALIC! PCO2 , whereas cardiac performance, oxygen consumption and citrate synthase activity were not significantly affected by elevated ITALIC! PCO2 Acclimation time had a significant effect on ventilation rate, stroke volume, cardiac output and citrate synthase activity, such that all metrics increased over the 4 week exposure period. These results suggest that juvenile emerald rockcod are robust to near-future increases in OA and may have the capacity to adjust for future increases in ITALIC! PCO2  by increasing acid-base compensation through increased ventilation. PMID:26944503

  3. Experiments and modeling of variably permeable carbonate reservoir samples in contact with CO₂-acidified brines

    SciTech Connect

    Smith, Megan M.; Hao, Yue; Mason, Harris E.; Carroll, Susan A.

    2014-12-31

    Reactive experiments were performed to expose sample cores from the Arbuckle carbonate reservoir to CO₂-acidified brine under reservoir temperature and pressure conditions. The samples consisted of dolomite with varying quantities of calcite and silica/chert. The timescales of monitored pressure decline across each sample in response to CO₂ exposure, as well as the amount of and nature of dissolution features, varied widely among these three experiments. For all samples cores, the experimentally measured initial permeability was at least one order of magnitude or more lower than the values estimated from downhole methods. Nondestructive X-ray computed tomography (XRCT) imaging revealed dissolution features including “wormholes,” removal of fracture-filling crystals, and widening of pre-existing pore spaces. In the injection zone sample, multiple fractures may have contributed to the high initial permeability of this core and restricted the distribution of CO₂-induced mineral dissolution. In contrast, the pre-existing porosity of the baffle zone sample was much lower and less connected, leading to a lower initial permeability and contributing to the development of a single dissolution channel. While calcite may make up only a small percentage of the overall sample composition, its location and the effects of its dissolution have an outsized effect on permeability responses to CO₂ exposure. The XRCT data presented here are informative for building the model domain for numerical simulations of these experiments but require calibration by higher resolution means to confidently evaluate different porosity-permeability relationships.

  4. Corrosion Fatigue Behavior of 316LN SS in Acidified Sodium Chloride Solution at Applied Potential

    NASA Astrophysics Data System (ADS)

    Poonguzhali, A.; Pujar, M. G.; Mallika, C.; Mudali, U. Kamachi

    2015-05-01

    The influence of acidified 1 M NaCl solution by addition of 2 ml/L of HCl on the cyclic plastic deformation of AISI Type 316LN SS containing 0.07 wt.% and 0.22 wt.% N was investigated as a function of the applied potentials. The corrosion fatigue (CF) behavior of stainless steel (SS) was explained vis-a-vis the dislocation behavior, the propensity to form microcracks, and the evolution of the current transients based on the studies carried out at both room-temperature and boiling conditions. CF experiments were conducted using round tensile specimens at a stress ratio of 0.5 and a frequency of 0.1 Hz. Two different kinds of damage mechanisms were observed (I) the damage mechanism in the stable-passive state was correlated with the localization of the anodic dissolution due to a depassivation-repassivation process, whereas (II) the cyclic stress induced pitting corrosion in the metastable pitting state, which resulted in formation of microcracks. The study of the microcracking process and its evolution is a key to the physical mechanism by which the fatigue life of stainless steels would be affected in an aqueous corrosive solution under the applied potential.

  5. Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa

    PubMed Central

    Wilton, Mike; Charron-Mazenod, Laetitia; Moore, Richard

    2015-01-01

    Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid l-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype. PMID:26552982

  6. Trichodesmium’s strategies to alleviate phosphorus limitation in the future acidified oceans.

    PubMed

    Spungin, Dina; Berman-Frank, Ilana; Levitan, Orly

    2014-06-01

    Global warming may exacerbate inorganic nutrient limitation, including phosphorus (P), in the surface waters of tropical oceans that are home to extensive blooms of the marine diazotrophic cyanobacterium, Trichodesmium. We examined the combined effects of P limitation and pCO(2), forecast under ocean acidification scenarios, on Trichodesmium erythraeum IMS101 cultures. We measured nitrogen acquisition,glutamine synthetase activity, C uptake rates, intracellular Adenosine Triphosphate (ATP) concentration and the pool sizes of related key proteins. Here, we present data supporting the idea that cellular energy re-allocation enables the higher growth and N(2) fixation rates detected in Trichodesmium cultured under high pCO(2). This is reflected in altered protein abundance and metabolic pools. Also modified are particulate organic carbon and nitrogen production rates,enzymatic activities, and cellular ATP concentrations. We suggest that adjusting these cellular pathways to changing environmental conditions enables Trichodesmium to compensate for low P availability and to thrive in acidified oceans. Moreover, elevated pCO(2) could provide Trichodesmium with a competitive dominance that would extend its niche, particularly in P-limited regions of the tropical and subtropical oceans.

  7. Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa.

    PubMed

    Wilton, Mike; Charron-Mazenod, Laetitia; Moore, Richard; Lewenza, Shawn

    2016-01-01

    Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid L-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype. PMID:26552982

  8. Leaf-associated fungal diversity in acidified streams: insights from combining traditional and molecular approaches.

    PubMed

    Clivot, Hugues; Cornut, Julien; Chauvet, Eric; Elger, Arnaud; Poupin, Pascal; Guérold, François; Pagnout, Christophe

    2014-07-01

    We combined microscopic and molecular methods to investigate fungal assemblages on alder leaf litter exposed in the benthic and hyporheic zones of five streams across a gradient of increasing acidification for 4 weeks. The results showed that acidification and elevated Al concentrations strongly depressed sporulating aquatic hyphomycetes diversity in both zones of streams, while fungal diversity assessed by denaturing gradient gel electrophoresis (DGGE) appeared unaffected. Clone library analyses revealed that fungal communities on leaves were dominated by members of Ascomycetes and to a lesser extent by Basidiomycetes and Chytridiomycetes. An important contribution of terrestrial fungi was observed in both zones of the most acidified stream and in the hyporheic zone of the reference circumneutral stream. The highest leaf breakdown rate was observed in the circumneutral stream and occurred in the presence of both the highest diversity of sporulating aquatic hyphomycetes and the highest contribution to clone libraries of sequences affiliated with aquatic hyphomycetes. Both methods underline the major role played by aquatic hyphomycetes in leaf decomposition process. Our findings also bring out new highlights on the identity of leaf-associated fungal communities and their responses to anthropogenic alteration of running water ecosystems.

  9. Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa.

    PubMed

    Wilton, Mike; Charron-Mazenod, Laetitia; Moore, Richard; Lewenza, Shawn

    2015-11-09

    Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid L-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype.

  10. Ensemble modeling of flows in ungaged catchments

    NASA Astrophysics Data System (ADS)

    McIntyre, N.; Wheater, H.; Lee, H.; Young, A.; Wagener, T.

    2005-12-01

    The established approach to rainfall-runoff model regionalisation is regression of model parameters (MPs) against numeric catchment descriptors (CDs). We argue that, due to its fundamental limitations, further refinement of the regression method is not the optimum way forward, and we introduce an alternative method based on weighed averaging and ensemble modelling. The new method consists of the following basic steps: 1) A sample of successful models is identified for each of a number of `donor' gaged catchments. 2) Each model is assigned a weight based on how well it has performed. 3) This weight is updated based on the similarity of the associated catchment to the `target' ungaged catchment. 4) All models with non-zero weight are applied to the target catchment, to produce an ensemble time-series and a weighted average prediction. The theoretical advantage is that MP interactions are not neglected or linearized to facilitate regression. The practical attraction is the ease with which all sources of uncertainty (e.g. data, CD, equifinality, model structure) can be integrated into the pool of models and the weighting scheme. A case study of daily data from 127 non-urban UK catchments is presented. A single conceptual model structure is used (a five-parameter probability distributed model) so that, in this case, differences in models are defined only by the MP sets. Each of the 127 catchments is, in turn, considered to be ungaged, so that candidate models can be drawn from up to 126 donor catchments. Relative weights are proportional to a quantitative measure of donor-target catchment similarity. Various schemes for defining catchment similarity are applied, based on CDs relating mainly to soil type, catchment size and climate. Using the models of the ten most similar catchments provided the best weighted average simulations, both in terms of NSE and a low-flow objective function. Using this scheme, in 90% of low-permeability catchments the prediction NSE was within

  11. Linking Stream Nitrate to Forest Response and Recovery after Severe Bark Beetle Infestation (Invited)

    NASA Astrophysics Data System (ADS)

    Rhoades, C.; Hubbard, R. M.; Elder, K.

    2013-12-01

    Biogeochemical responses and ecosystem recovery from bark beetle outbreaks are influenced by pre-disturbance forest structure and composition and catchment conditions. Over the past decade, the mountain pine bark beetle (Dendroctonus ponderosae) has killed mature lodgepole pine (Pinus contorta) trees at the Fraser Experimental Forest and throughout the Colorado Rockies. Here we compare stream nitrogen (N) concentrations during the outbreak with data from the previous two decades in four research catchments with distinct forest management history, stand age structure and watershed characteristics. In two old growth forest catchments, stream nitrate concentrations were significantly higher during the infestation in the snowmelt and base flow seasons. The beetle infestation elevated nitrate export 43 and 74% in these two catchments though the amounts of N released in streamwater (0.04 and 0.15 kg N ha-1) were < 2% of annual atmospheric inputs. In contrast, nitrate concentrations were unaffected by beetle infestation in two catchments comprised of a mixture of second-growth (30-60 year old) and old-growth (250-350 year old) forest stands where the density of residual live trees was higher on average. Mortality of overstory trees from bark beetles has stimulated the growth of understory and overstory trees with likely consequences for nutrient demand and retention in recovering forests.

  12. Seasonal and event-scale controls on dissolved organic carbon and nitrate flushing from catchments

    NASA Astrophysics Data System (ADS)

    Sebestyen, S. D.; Boyer, E. W.; Shanley, J. B.; Doctor, D. H.

    2005-05-01

    To explore terrestrial and aquatic linkages controlling nutrient dynamics in forested catchments, we collected high-frequency samples from 2002 to 2004 at the Sleepers River Research Watershed in northeastern Vermont USA. We measured DOC (dissolved organic carbon), SUVA (specific UV absorbance), nitrate, and major ion concentrations over a wide range of flow conditions. In addition, weekly samples since 1991 provide a longer term record of stream nutrient fluxes. During events, DOC concentrations increased with flow consistent with the flushing of a large reservoir of mobile organic carbon from forest soils. Higher concentrations of DOC and SUVA in the growing versus dormant season illustrated seasonal variation in sources, characteristics (i.e. reactivity), availability, and controls on the flushing response of organic matter from the landscape to streams. In contrast, stream nitrate concentrations increased with flow but only when catchments "wetted-up" after baseflow periods. Growing season stream nitrate responses were dependent on short-term antecedent moisture conditions indicating rapid depletion of the soil nitrate reservoir when source areas became hydrologically connected to streams. While the different response patterns emphasized variable source and biogeochemical controls in relation to flow patterns, coupled carbon and nitrogen biogeochemical processes were also important controls on stream nutrient fluxes. In particular, leaf fall was a critical time when reactive DOC from freshly decomposing litter fueled in-stream consumption of nitrate leading to sharp declines of stream nitrate concentrations. Our measurements highlight the importance of "hot spots" and "hot moments" of biogeochemical and hydrological processes that control stream responses. Furthermore, our work illustrates how carbon, nitrogen, and water cycles are coupled in catchments, and provides a conceptual model for future work aimed at modeling forest stream hydrochemistry at the

  13. Quantifying catchment scale soil variability in Marshall Gulch, Santa Catalina Mountains Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Holleran, M.; Rasmussen, C.

    2012-12-01

    Quantifying regolith variation, both chemical and physical yields insights to the evolution of the subsurface. In this study we aim to quantify soil variability within a forested catchment, Marshall Gulch, AZ. Marshall Gulch (MG) lies within the Coronado National Forest, part of the Jemez River Basin-Santa Catalina Mountains Critical Zone Observatory (CZO). MG is 5-hectare, mixed-conifer forested catchment situated on granitic parent material, with a mean elevation of 2400m, mean annual temperature of 8°C and mean annual precipitation of 75 cm. To ensure samples sites capture landscape variability, principal component analysis (PCA) were run on NAIP imagery and additional ancillary data from the study area. The PCA determined input layers of soil depth, slope, soil wetness index, NDVI and NAIP bands 3/2 as the variables needed to capture the landscape variability of MG. A conditioned Latin Hyper Cube (cLHC) model was then utilized to randomly determine 20 sample locations within the catchment to equally represent the six input layers, as determined from the PCA. Regolith profiles were described and sampled at all 20 locations. At each sample site a soil pit was dug to refusal (paralithic contact) and sampled according to genetic horizon. Each sample was then analyzed using methods of X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), particle size, color, pH, EC, C/N isotopes, and loss on ignition (LOI) to characterize chemical and physical soil properties. By quantifying chemical denudation and mineralogical variability of the collected soils, we establish a proxy for regolith weathering both on the profile scale (1m2) as well as the catchment scale (50k m2). GIS spatial techniques enable us to produce maps depicting the variability of soil properties. We confidently extrapolate our findings (pH, depth to paralithic contact, color, mineralogy etc.) throughout the entirety of the MG field site, generating a high-resolution understanding of the processes shaping

  14. Land Use Change Effects on Catchment Runoff Response in a Humid Tropical Montane Region

    NASA Astrophysics Data System (ADS)

    Munoz Villers, L. E.; McDonnell, J.; Geissert Kientz, D. R.

    2014-12-01

    The provision and regulation of water flows in catchments is probably the most important ecosystem functioning of tropical montane cloud forests (TMCF), however its hydrological dynamics and impacts associated with forest conversion remain very poorly understood. The present study aimed to compare the annual, seasonal and event-scale streamflow patterns and runoff generation processes of three neighbouring headwater catchments in eastern Mexico with similar pedological and geological characteristics, but different land cover: old-growth TMCF, 20 yr-old naturally regenerating TMCF and a heavily grazed pasture. We used a 2 yr record of rainfall and stream flow data in combination with isotope and chemical tracer data collected for a series of storms during a 6-week period of increasing antecedent wetness (wetting-up cycle). Our results showed that annual and seasonal streamflow patterns in the mature and secondary forest were similar. Conversely, the pasture showed higher annual streamflow (10%), however 50% on average lower baseflow at the end of the dry season, associated probably to more gentle slopes in combination with lower soil infiltration capacity, and thus reduced recharge of subsurface water storages. During the wetting-up cycle, storm runoff ratios increased at all three catchments (from 11 to 54% for the mature forest, 7 to 52% for the secondary forest and 3 to 59% for the pasture). With the increasing antecedent wetness, the analysis showed progressive increases of pre-event water contributions to total stormflow (from 35 to 99% in the mature forest, 26 to 92% in the secondary forest and 64 to 97% in the pasture). At all sites, rainfall-runoff responses were dominated by subsurface flow processes. However, for the largest and most intense storm sampled (typically occurring once every 2 yr), the event water contribution in the pasture (34%) was much higher than in the forests (5% on average), indicating that rainfall infiltration capacity of the pasture

  15. Pseudo Paired Catchments Analysis to Assess the Impact of Urbanization on Catchment Hydrology

    NASA Astrophysics Data System (ADS)

    Salavati, B.; Oudin, L.; Furusho, C.; Ribstein, P.

    2014-12-01

    Paired catchments analysis provides a robust approach to assess the impact of land use changes on catchment's hydrological response. This approach is limited by the availability of data for two neighbor catchments with and without land use changes under similar climate conditions. Thus, hydrological modelling approaches are also very popular since they do not depend on data of a reference catchment. In the present study, 70 urbanized and non-urbanized paired catchments were selected in the United States. Unit housing density maps over the 1940-2010 time period were used to reconstruct historic impervious area extents with aproximatly the same resolution as the National Land Cover Database (NLCD) maps. Two approaches were compared to assess the impact of urbanization on catchment-scale hydrology: the classical paired catchments approach using observed flow time series and an alternative paired catchments approach involving hydrological modeling that allows to simulate a virtual control catchment. To this aim, the GR4J model, a conceptual daily 4-parameter hydrological model, was used. The parameters of the model calibrated on the pre urbanization period were used to predict the streamflow that would have occurred in the urban catchment if the urbanization had not taken place. Then, classical statistical methods involving ANCOVA were used to detect the significance and to quantify the change on the hydrological responses due to land use changes. Results show that the two approaches lead to similar conclusions on the impact of urbanization on catchment hydrology. Thus, the modelling approach provides a relevant alternative for case studies where data of reference catchments are not available.

  16. Effect of bedrock permeability on stream base flow mean transit time scaling relations: 1. A multiscale catchment intercomparison

    NASA Astrophysics Data System (ADS)

    Hale, V. Cody; McDonnell, Jeffrey J.

    2016-02-01

    The effect of bedrock permeability and underlying catchment boundaries on stream base flow mean transit time (MTT) and MTT scaling relationships in headwater catchments is poorly understood. Here we examine the effect of bedrock permeability on MTT and MTT scaling relations by comparing 15 nested research catchments in western Oregon; half within the HJ Andrews Experimental Forest and half at the site of the Alsea Watershed Study. The two sites share remarkably similar vegetation, topography, and climate and differ only in bedrock permeability (one poorly permeable volcanic rock and the other more permeable sandstone). We found longer MTTs in the catchments with more permeable fractured and weathered sandstone bedrock than in the catchments with tight, volcanic bedrock (on average, 6.2 versus 1.8 years, respectively). At the permeable bedrock site, 67% of the variance in MTT across catchments scales was explained by drainage area, with no significant correlation to topographic characteristics. The poorly permeable site had opposite scaling relations, where MTT showed no correlation to drainage area but the ratio of median flow path length to median flow path gradient explained 91% of the variance in MTT across seven catchment scales. Despite these differences, hydrometric analyses, including flow duration and recession analysis, and storm response analysis, show that the two sites share relatively indistinguishable hydrodynamic behavior. These results show that similar catchment forms and hydrologic regimes hide different subsurface routing, storage, and scaling behavior—a major issue if only hydrometric data are used to define hydrological similarity for assessing land use or climate change response.

  17. Complex responses of intertidal molluscan embryos to a warming and acidifying ocean in the presence of UV radiation.

    PubMed

    Davis, Andrew R; Coleman, Daniel; Broad, Allison; Byrne, Maria; Dworjanyn, Symon A; Przeslawski, Rachel

    2013-01-01

    Climate change and ocean acidification will expose marine organisms to synchronous multiple stressors, with early life stages being potentially most vulnerable to changing environmental conditions. We simultaneously exposed encapsulated molluscan embryos to three abiotic stressors-acidified conditions, elevated temperate, and solar UV radiation in large outdoor water tables in a multifactorial design. Solar UV radiation was modified with plastic filters, while levels of the other factors reflected IPCC predictions for near-future change. We quantified mortality and the rate of embryonic development for a mid-shore littorinid, Bembicium nanum, and low-shore opisthobranch, Dolabrifera brazieri. Outcomes were consistent for these model species with embryos faring significantly better at 26°C than 22°C. Mortality sharply increased at the lowest temperature (22°C) and lowest pH (7.6) examined, producing a significant interaction. Under these conditions mortality approached 100% for each species, representing a 2- to 4-fold increase in mortality relative to warm (26°C) non-acidified conditions. Predictably, development was more rapid at the highest temperature but this again interacted with acidified conditions. Development was slowed under acidified conditions at the lowest temperature. The presence of UV radiation had minimal impact on the outcomes, only slowing development for the littorinid and not interacting with the other factors. Our findings suggest that a warming ocean, at least to a threshold, may compensate for the effects of decreasing pH for some species. It also appears that stressors will interact in complex and unpredictable ways in a changing climate.

  18. Complex Responses of Intertidal Molluscan Embryos to a Warming and Acidifying Ocean in the Presence of UV Radiation

    PubMed Central

    Davis, Andrew R.; Coleman, Daniel; Broad, Allison; Byrne, Maria; Dworjanyn, Symon A.; Przeslawski, Rachel

    2013-01-01

    Climate change and ocean acidification will expose marine organisms to synchronous multiple stressors, with early life stages being potentially most vulnerable to changing environmental conditions. We simultaneously exposed encapsulated molluscan embryos to three abiotic stressors—acidified conditions, elevated temperate, and solar UV radiation in large outdoor water tables in a multifactorial design. Solar UV radiation was modified with plastic filters, while levels of the other factors reflected IPCC predictions for near-future change. We quantified mortality and the rate of embryonic development for a mid-shore littorinid, Bembicium nanum, and low-shore opisthobranch, Dolabrifera brazieri. Outcomes were consistent for these model species with embryos faring significantly better at 26°C than 22°C. Mortality sharply increased at the lowest temperature (22°C) and lowest pH (7.6) examined, producing a significant interaction. Under these conditions mortality approached 100% for each species, representing a 2- to 4-fold increase in mortality relative to warm (26°C) non-acidified conditions. Predictably, development was more rapid at the highest temperature but this again interacted with acidified conditions. Development was slowed under acidified conditions at the lowest temperature. The presence of UV radiation had minimal impact on the outcomes, only slowing development for the littorinid and not interacting with the other factors. Our findings suggest that a warming ocean, at least to a threshold, may compensate for the effects of decreasing pH for some species. It also appears that stressors will interact in complex and unpredictable ways in a changing climate. PMID:23405238

  19. Predominant Runoff Components During Heavy Rainfall Events on Cultivated Catchment

    NASA Astrophysics Data System (ADS)

    Jeřábek, J.; Zumr, D.; Strouhal, L.

    2015-12-01

    The fact that flash floods initiated in arable catchments are often accompanied by massive sediment and nutrient loads often leads to the assumption that surface runoff is the principle pathway by which runoff reaches watercourses. But the hydrology of cultivated catchments has its specific features due to the temporary variable topsoil properties and a sharp divide between topsoil and compacted subsoil. Under various conditions the prevailing runoff mechanisms may vary from surface runoff to subsurface runoff or deep percolation. On the basis of an evaluation of several rainfall-runoff events in a representative agricultural catchment (Nucice, Czech Republic), we show that runoff from cultivated land may be generated in a way similar to that seen on forested slopes, where shallow subsurface runoff is the predominant pathway. To identify the predominant runoff pathway, we employed a combination of turbidity measurements and stream discharge data. Although we observed temporal variability of topsoil properties attributable to seasonal weather changes and agricultural activities, e.g. bulk density and porosity, runoff generation was mainly driven by precipitation characteristics and the initial catchment saturation. The concept of the runoff formation was also observed during plot scale experiments with rainfall simulator. Various initial soil moisture conditions, and vegetation stages delimited the simulations. Variable proportions of both monitored runoff components were observed in relation to rainfall intensity and duration, ranging from zero surface runoff to a distinct dominance of surface runoff. Even with the highest tested precipitation intensities, surface runoff always formed due to saturation excess of the topsoil, irrespective of the topsoil properties and crops. The experiments were numerically modelled and analysed to understand the effect of temporal variability in the macropores and intra-aggregate voids ratio within the topsoil. We used a

  20. Quantifying sediment source contributions in coastal catchments impacted by the Fukushima nuclear accident with carbon and nitrogen elemental concentrations and stable isotope ratios

    NASA Astrophysics Data System (ADS)

    Laceby, J. Patrick; Huon Huon, Sylvain; Onda, Yuichi; Evrard, Olivier

    2016-04-01

    The Fukushima Dai-ichi Nuclear Power Plant accidental release of radioactive contaminants resulted in the significant fallout of radiocesium over several coastal catchments in the Fukushima Prefecture. Radiocesium, considered to be the greatest risk to the short and long term health of the local community, is rapidly bound to fine soil particles and thus is mobilized and transported during soil erosion and runoff processes. As there has been a broad-scale decontamination of rice paddy fields and rural residential areas in the contaminated region, one important long term question is whether there is, or may be, a downstream transfer of radiocesium from forests that covered over 65% of the most contaminated region. Accordingly, carbon and nitrogen elemental concentrations and stable isotope ratios are used to determine the relative contributions of forests and rice paddies to transported sediment in three contaminated coastal catchments. Samples were taken from the three main identified sources: cultivated soils (rice paddies and fields, n=30), forest soils (n=45), and subsoils (channel bank and decontaminated soils, n = 25). Lag deposit sediment samples were obtained from five sampling campaigns that targeted the main hydrological events from October 2011 to October 2014. In total, 86 samples of deposited sediment were analyzed for particulate organic matter elemental concentrations and isotope ratios, 24 from the Mano catchment, 44 from the Niida catchment, and 18 from the Ota catchment. Mann-Whitney U-tests were used to examine the source discrimination potential of this tracing suite and select the appropriate tracers for modelling. The discriminant tracers were modelled with a concentration-dependent distribution mixing model. Preliminary results indicate that cultivated sources (predominantly rice paddies) contribute disproportionately more sediment per unit area than forested regions in these contaminated catchments. Future research will examine if there are

  1. An acidified thermostabilizing mini-peptide derived from the carboxyl extension of the larger isoform of the plant Rubisco activase.

    PubMed

    Zhang, Mengru; Li, Xujuan; Yang, Yumei; Luo, Zhu; Liu, Chang; Gong, Ming; Zou, Zhurong

    2015-10-20

    Thermostable fusion peptide partners are valuable in engineering thermostability in proteins. We evaluated the Arabidopsis counterpart (AtRAce) and an acidified derivative (mRAce) of the conserved carboxyl extension (RAce) of plant Rubisco activase (RCA) for their thermostabilizing properties in Escherichia coli and Saccharomyces cerevisiae using a protein fusion strategy. We used AtRAce and mRAce as fusion tails for the thermolabile protein RCA2 from Arabidopsis thaliana and Nicotiana tabacum. The homologous fusion of AtRAce with Arabidopsis RCA2 and the heterologous fusion of AtRAce with tobacco RCA2 increased the thermostability of both proteins. The acidified derivative mRAce conferred greater thermostability upon both proteins as compared with AtRAce. Moreover, mRAce enhanced the thermostability of other two thermolabile proteins from Jatropha curcas: the cytosolic ascorbate peroxidase 1 (JcAPX1) and the TATA-box binding protein isoform 1 (JcTBP1). We further report - for the first time - that JcTBP1 mediates heat tolerance in vivo in yeast. Thus, our study identifies a C-terminal acidic mini-peptide - the acidified derivative mRAce - with potential uses in improving the thermostability of heat-labile proteins and their associated heat tolerance in host organisms. PMID:26321073

  2. [Effects of simulated acid rain and its acidified soil on soluble sugar and nitrogen contents of wheat seedlings].

    PubMed

    Tong, Guanhe; Liang, Huiling

    2005-08-01

    The study showed that the cation release of simulated rain caused soil acidification and base ions release. With the decrease of simulated acid rain pH from 5.6 to 2.5, the acid rain-leached soil pH decreased from 6.06 to 3.41, and its total amount of exchange base ions decreased from 56.5 to 41.1 mmol x kg(-1). Spraying simulated acid rain on the shoots of wheat seedlings planted on such acidified soils caused a rapid decrease in the soluble sugar and nitrogen contents of wheat seedlings, and reduced some of their physiological activities. The effect of spraying simulated acid rain on the soluble sugar, nitrogen, and chlorophyll contents and photosynthetic rate of wheat stems and leaves was larger than that of acidified soil, while the effect of the latter on the soluble sugar and nitrogen contents and the physiological activity of NR and GOGAT in root system of wheat seedlings was larger than that of the former. The intensive acid rain of pH < or = 3.0 and the corresponding acidified soil had an obvious harm to the growth and physiological activity of wheat seedlings.

  3. An acidified thermostabilizing mini-peptide derived from the carboxyl extension of the larger isoform of the plant Rubisco activase.

    PubMed

    Zhang, Mengru; Li, Xujuan; Yang, Yumei; Luo, Zhu; Liu, Chang; Gong, Ming; Zou, Zhurong

    2015-10-20

    Thermostable fusion peptide partners are valuable in engineering thermostability in proteins. We evaluated the Arabidopsis counterpart (AtRAce) and an acidified derivative (mRAce) of the conserved carboxyl extension (RAce) of plant Rubisco activase (RCA) for their thermostabilizing properties in Escherichia coli and Saccharomyces cerevisiae using a protein fusion strategy. We used AtRAce and mRAce as fusion tails for the thermolabile protein RCA2 from Arabidopsis thaliana and Nicotiana tabacum. The homologous fusion of AtRAce with Arabidopsis RCA2 and the heterologous fusion of AtRAce with tobacco RCA2 increased the thermostability of both proteins. The acidified derivative mRAce conferred greater thermostability upon both proteins as compared with AtRAce. Moreover, mRAce enhanced the thermostability of other two thermolabile proteins from Jatropha curcas: the cytosolic ascorbate peroxidase 1 (JcAPX1) and the TATA-box binding protein isoform 1 (JcTBP1). We further report - for the first time - that JcTBP1 mediates heat tolerance in vivo in yeast. Thus, our study identifies a C-terminal acidic mini-peptide - the acidified derivative mRAce - with potential uses in improving the thermostability of heat-labile proteins and their associated heat tolerance in host organisms.

  4. [Effects of simulated acid rain and its acidified soil on soluble sugar and nitrogen contents of wheat seedlings].

    PubMed

    Tong, Guanhe; Liang, Huiling

    2005-08-01

    The study showed that the cation release of simulated rain caused soil acidification and base ions release. With the decrease of simulated acid rain pH from 5.6 to 2.5, the acid rain-leached soil pH decreased from 6.06 to 3.41, and its total amount of exchange base ions decreased from 56.5 to 41.1 mmol x kg(-1). Spraying simulated acid rain on the shoots of wheat seedlings planted on such acidified soils caused a rapid decrease in the soluble sugar and nitrogen contents of wheat seedlings, and reduced some of their physiological activities. The effect of spraying simulated acid rain on the soluble sugar, nitrogen, and chlorophyll contents and photosynthetic rate of wheat stems and leaves was larger than that of acidified soil, while the effect of the latter on the soluble sugar and nitrogen contents and the physiological activity of NR and GOGAT in root system of wheat seedlings was larger than that of the former. The intensive acid rain of pH < or = 3.0 and the corresponding acidified soil had an obvious harm to the growth and physiological activity of wheat seedlings. PMID:16262064

  5. Runoff and suspended sediment transport after plantation interventions in experimental catchments with contrasting rainfall conditions, Chile

    NASA Astrophysics Data System (ADS)

    Iroume, A.; Schuller, P.; Bronstert, A.; Carey, P.; Palacios, H.; Ulloa, H.

    2012-04-01

    Experimental catchments located in sites with contrasting annual rainfall (Nacimiento, 37° 28" S, 72° 42" W, long term mean annual rainfall ~ 1,200 mm, and Los Ulmos, 40° 02" S, 73° 06" W, long term mean annual rainfall ~ 2,500 mm) are been monitored to study the long term effects of different forest plantation practices on runoff and suspended sediment transport. In each site, one control and one treatment catchment (12.6 and 7.7 ha in Nacimiento and 19.8 and 7.7 ha in Los Ulmos) are monitored. All the catchments are controlled by purpose-built V-notch weir gauging stations equipped with continuous water level recorders and suspended sediment is quantified in these stations from automatically collected integrated water samples. After a calibration period the plantation of one paired catchment in each site was clearfelled. Treated and control catchments will be from now on identified as NT and LUT and NC and LUT respectively. The Pinus radiata plantation in NT was clearfelled during the first half of April 2010, while the Eucalyptus globulus plantation in LUT was partially clearfelled in November 2009 and then completed in April 2010. After clearfelling runoff increases were observed in both harvested catchments as compared with the pre-treatment runoff trend between treatment and control catchments. In the Nacimiento site, mean monthly values for suspended sediment loads registered for the pre, during and post-treatment periods are not much different for NT and NC. For the pre-treatment period (April 2008 to March 2010), mean monthly suspended sediment loads were 12.8 kg/ha in NC and 16.2 kg/ha in NT, and 0.9 kg/ha in NC and 2.7 kg/ha in NT during the harvesting operations (April 2010). Mean monthly suspended sediment loads during the first year of the post-harvesting period (May to December 2010) were 69.9 kg/ha in NC and 59 kg/ha in NT and 0.9 kg/ha in NC and 6.2 kg/ha in NT during the year after clearfelling (January to June 2011). Year 2010 was extremely

  6. The soil water regime of stony soils in a mountain catchment

    NASA Astrophysics Data System (ADS)

    Hlaváčiková, Hana; Danko, Michal; Holko, Ladislav; Hlavčo, Jozef; Novák, Viliam

    2016-04-01

    Investigation of processes related to runoff generation is an important topic in catchment hydrology. Observations are usually carried out in small catchments or on hillslopes. Many of such catchments are located in mountain or forested areas. From many studies it is evident that soil conditions and soil characteristics are one of the crucial factors in runoff generation. Mountainous or forest soils have usually high rock fragments content. Nevertheless, the influence of soil stoniness on water flow was not sufficiently studied up to now at catchment and hillslope scales due to flow formation complexity or problems with stony soil properties measurement (installing measuring devices, interpretation of measured data). Results of this work can be divided in two groups: (1) hydrophysical properties of stony soils measurements, and (2) water flow dynamic modelling in stony soils. Properties of stony soils were measured in the Jalovecky creek catchment, the Western Tatra Mts., Slovakia. Altitude of particular study sites varies from 780 to1500 m a.s.l. We measured and analyzed the stoniness of reference soil profiles, as well as retention properties of stony soils (fine soil fraction and rock fragments separately) and hydraulic conductivities of surface and subsurface soil layers. The methodology for determination of the effective hydrophysical properties of a stony soil (later used in modelling) was proposed using results from measurements, calculation, and numerical Darcy experiments. Modelling results show that the presence of rock fragments with low water retention in a stony soil with moderate or high stoniness can cause the soil water storage decrease by 16-31% in compared to the soil without rock fragments. In addition, decreased stony soil retention capacity resulted in faster outflow increase at the bottom of the soil profile during non-ponding infiltration. Furthermore, the presence of rock fragments can increase maximum outflow value. It is not possible to

  7. Black, grey and white-box approaches to understanding catchment-wide hydrologic connectivity

    NASA Astrophysics Data System (ADS)

    Ali, G. A.; Roy, A. G.

    2009-12-01

    Connectivity is associated with nonlinear hydrological responses as it is believed to lead to drastic changes in the delivery of stormwater to the stream. Quantitative evidence of connectivity is therefore needed if the concept is to serve as a diagnostic tool for hydrologic behaviours. Recent publications advocate that geostatistical connectivity is a universal measure as it transcends catchment idiosyncracies and allows for the detection of transitions and thresholds in flow processes. Yet, the geostatistical framework failed to reflect threshold change in runoff response in a temperate humid forested catchment (Mont St-Hilaire, Quebec). In this study based on a forested catchment from the Canadian Shield (St-Hippolyte, Quebec), we use three types of hydrological data analysis in searching for evidence of connectivity: (1) statistical classification techniques applied to meteorological records and storm hydrographs; (2) end-member mixing computations performed on stream and source areas geochemistry; and (3) catchment-wide multiple-depths soil moisture data subjected to pattern analysis. These methods correspond respectively to black, grey and white-box approaches towards understanding connectivity. Since the methods can be discriminated by accessibility, physical basis, robustness and spatial discretization, results obtained are compared to assess catchment behavior and prediction uncertainty. The black-box approach reveals that catchment responses, labeled as low/high magnitude and slow/quick timing, can be predicted from meteorological thresholds. It yields indirect evidence of connectivity by suggesting that a relationship between response types and antecedent conditions can be found if assumed nonlinear. The grey-box approach is helpful in identifying time-variable contributing sources to streamflow. Intermediate discharge levels are fed by an enhanced near-surface riparian-stream connection, while both riparian and hillslope areas produce overland flow when

  8. Catchment Classification: Connecting Climate, Structure and Function

    NASA Astrophysics Data System (ADS)

    Sawicz, K. A.; Wagener, T.; Sivapalan, M.; Troch, P. A.; Carrillo, G. A.

    2010-12-01

    Hydrology does not yet possess a generally accepted catchment classification framework. Such a classification framework needs to: [1] give names to things, i.e. the main classification step, [2] permit transfer of information, i.e. regionalization of information, [3] permit development of generalizations, i.e. to develop new theory, and [4] provide a first order environmental change impact assessment, i.e., the hydrologic implications of climate, land use and land cover change. One strategy is to create a catchment classification framework based on the notion of catchment functions (partitioning, storage, and release). Results of an empirical study presented here connects climate and structure to catchment function (in the form of select hydrologic signatures), based on analyzing over 300 US catchments. Initial results indicate a wide assortment of signature relationships with properties of climate, geology, and vegetation. The uncertainty in the different regionalized signatures varies widely, and therefore there is variability in the robustness of classifying ungauged basins. This research provides insight into the controls of hydrologic behavior of a catchment, and enables a classification framework applicable to gauged and ungauged across the study domain. This study sheds light on what we can expect to achieve in mapping climate, structure and function in a top-down manner. Results of this study complement work done using a bottom-up physically-based modeling framework to generalize this approach (Carrillo et al., this session).

  9. Understanding Pesticide Behaviour At The Catchment Scale

    NASA Astrophysics Data System (ADS)

    Kannan, N.; White, S. M.; Worrall, F.; Pendlington, D.; Groves, S.

    Pesticides in stream flow at the outlet of a 142ha catchment in Eastern England (Col- worth, Bedfordshire), have been monitored since October 1999. About 50% of the total catchment is directly controlled within one farm and a rotation of wheat, oil seed rape, grass, linseed, beans and peas is grown. The data from this catchment are being used to investigate the performance of the USDA SWAT contaminant transport pack- age at the catchment scale. Three years of stream flow and climate data are available with a useful set of pesticide application and detection data. Following calibration and validation of the hydrology of the catchment, pesticide modelling was carried out for tebuconazole, terbutryn, and terbuthylazine. This paper reports on the results of a sen- sitivity analysis of the model, and the final calibrated pesticide component. Analysis of the results obtained show that the timing and decay of predicted pesticide concen- trations are correct. It is therefore recommended that SWAT can be used as a tool to understand pesticide behaviour at the catchment scale.

  10. Long-term variability in the water balances of the Plynlimon <