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Sample records for acidified forested catchment

  1. Runoff responses to forest thinning at plot and catchment scales in a headwater catchment draining Japanese cypress forest

    NASA Astrophysics Data System (ADS)

    Dung, Bui Xuan; Gomi, Takashi; Miyata, Shusuke; Sidle, Roy C.; Kosugi, Kenichiro; Onda, Yuichi

    2012-06-01

    SummaryWe 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 (catchment M5), and left the control catchment (M4) untreated. In both catchments, we monitored overland flow from hillslope plots and stream runoff from catchments at basin outlets over a 2-year pre-thinning period and a 2-year post-thinning period. Paired catchment analysis revealed that annual catchment runoff increased 240.7 mm after thinning. Delayed runoff increased significantly, while quick runoff followed similar patterns in the pre- and post-thinning periods. Flow duration in the ephemeral channel in catchment M5 increased from 56.9% in the pre-thinning period to 73.3% in the post-thinning period. Despite the changes in hydrological responses at the catchment scale, increases in overland flow were not significant. The increased availability of water in the soil matrix, caused by decreased interception loss and evapotranspiration, increased base flow after thinning. Based on the summarized data of previous studies together with this study, the effects of forest thinning on increases in runoff were less than partial harvesting in which the managed areas were concentrated within a watershed. We demonstrated that the effect of forest thinning was strongly scale dependent, an important finding for optimizing water and forest management in forested watersheds.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Phytotoxic substances in runoff from forested catchment areas

    NASA Astrophysics Data System (ADS)

    Grimvall, Anders; Bengtsson, Maj-Britt; Borén, Hans; Wahlström, Dan

    Runoff from different catchment areas in southern Sweden was tested in a root bioassay based on solution cultures of cucumber seedlings. Water samples from agricultural catchment areas produced no signs at all or only weak signs of inhibited root growth, whereas several water samples from catchment areas dominated by mires or coniferous forests produced visible root injuries. The most severe root injuries (very short roots, discolouration, swelling of root tips and lack of root hairs) were caused by samples from a catchment area without local emissions and dominated by old stands of spruce. Fractionation by ultrafiltration showed that the phytotoxic effect of these samples could be attributed to organic matter with a nominal molecular-weight exceeding 1000 or to substances associated with organic macromolecules. Experiments aimed at concentrating phytotoxic compounds from surface water indicated that the observed growth inhibition was caused by strongly hydrophilic substances. Previous reports on phytotoxic, organic substances of natural origin have emphasized interaction between plants growing close together. The presence of phytotoxic substances in runoff indicates that there is also a large-scale dispersion of such compounds.

  9. Effect of landscape form on export of dissolved organic carbon, iron, and phosphorus from forested stream catchments

    NASA Astrophysics Data System (ADS)

    Dillon, P. J.; Molot, L. A.

    1997-11-01

    Predicting the effects of climate change and atmospheric deposition on water quality requires predicting the effects of landscape form on export of substances downstream. In this paper, we present dissolved organic carbon (DOC), total phosphorus (TP), and iron (Fe) export data (1980-1992) for 20 relatively undisturbed, forested catchments draining into seven lakes in central Ontario and develop regression models of chemical export as functions of landscape composition. The extent of wetlands was correlated with export of DOC and TP; the proportion of the catchment covered by peatlands accounted for 78% of the variance in a regression model of long-term average DOC export and 76% of the variance in a model of color "export." Peatland coverage and Fe export together explained 76% of the variance in a long-term average TP export model, which is consistent with published experimental evidence that Fe facilitates P complexation with DOC in surface waters. The long-term average Fe export model was not significant when all 20 catchments were included. However, Fe export from the 14 catchments with thin tills was a function only of peatland coverage (R2 = 0.71), suggesting that Fe export is dependent to a large extent upon either the export of organic material or the reducing conditions. The long-term export models worked well when export of a substance was dominated by peatlands but was not very sensitive to the influence of mineral soils. The long-term average TP/DOC ratio was remarkably constant among most whole-lake catchments, ranging from 1.4 to 2.0 mg P/g C, the exception being the catchment of anthropogenically acidified Plastic Lake with a ratio of 0.8. Fe export to Plastic lake was also enriched relative to TP export compared with the other lakes. Therefore TP export to Plastic Lake may be limited by some mechanism related to acidification.

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

    SciTech Connect

    Lucie Erbanova; Martin Novak; Daniela Fottova; Barbora Dousova

    2008-10-01

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

  11. 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

  12. An ecohydrological framework for water yield changes of forested catchments due to forest decline and soil acidification

    SciTech Connect

    Caspary, H.J. )

    1990-06-01

    The effect of forest decline on water resources is not well described, for there have been no long-term measurements on catchments with declining forests. The precipitation/runoff relationship of the declining forests of the Eyach catchment in the Northern Black Forest/Federal Republic of Germany is analyzed. The uninhabited catchment is subdivided into four subcatchments (7, 10, 30, 52 km{sup 2}) and is totally covered with coniferous forest, mostly Norway spruce. Long-term monitoring from 1973 to 1986 indicates a significant increase in water yield and the runoff coefficient for the growing season, although there has been no extensive cutting in the catchment. An ecohydrological systems model was developed by the incorporation of field data and plant physiological processes to describe the increase in water yield. Field data include hydrological, hydrogeological, geological, soil-physical, soil-chemical, water-chemical, air-chemical, pollutant deposition, forest inventory, and forest decline field measurements from the Eyach catchment and comparable neighboring regions. The model indicates that the observed increase in water yield is likely to be caused by a reduction of forest transpiration. This change in water yield is linked to forest decline and soil acidification caused by anthropogenic sources of air pollution.

  13. 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...

  14. Seasonal changes of principal anions contents and other soil properties in acidified forest soils

    NASA Astrophysics Data System (ADS)

    Drabek, O.; Tejnecky, V.; Bradová, M.; Němeček, K.; Šebek, O.; Zenáhlíková, J.; Boruvka, L.

    2011-12-01

    Acidification of forest soil is a natural degradation process enhanced by anthropogenic activities. The depositions of principal inorganic anions are the main external acidity inputs to forest ecosystems. The aim of the study was to describe seasonal changes of sulphate and nitrate behaviour in soils and influence of their depositions on the selected forest soil properties. The following soil properties were investigated: soil pH, DOC, selected elements contents and Al species content. The Jizera Mountains area (Czech Republic) was chosen as a representative soil mountainous ecosystem affected by acidification. Soil and precipitation samples were collected at monthly intervals from April to October during the years 2008-2010 under beech and spruce stands. 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 in a "fresh" state. Unsieved fresh samples were extracted by deionised water and content of anions (sulphate, nitrate, chloride and fluoride) in these extracts were determined by ion-exchange chromatography (IC); the Al speciation was performed by means of HPLC/IC. The extracts were also used for determination of main elements content (Al, Ca, Mg, Ca, Na and Fe) by means of ICP-OES. Content of anions and main elements content, pH and conductivity were determined also in the precipitation samples (throughfall, stemflow and bulk). Statistically significant differences in distributions of monitored anions between the tested soil horizons were observed. The highest content of sulphate was determined in F and B horizons. On the contrary, contents of nitrate were highest in F horizons and lowest in B horizons. Higher annual variability in the investigated characteristics was proven for

  15. 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

  16. 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...

  17. 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...

  18. Sediment transport in steep forested catchments - An assessment of scale and disturbance

    NASA Astrophysics Data System (ADS)

    Hancock, G. R.; Hugo, J.; Webb, A. A.; Turner, L.

    2017-04-01

    Stream sediment loads (both bedload and suspended sediment) are problematic to measure due to the time and equipment needed. There is a dearth of such data sets globally let alone for Australia. However, such data are needed to quantify sediment transport type and rates, landscape evolution, effect of human disturbance as well as patterns and temporal response. Here we present the findings from 8 steepslope forested catchments dominated by headwater streams (size range 15-100 ha) 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 and there is 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. However catchment total load was found to be significantly related to catchment area. Of the 8 catchments examined here, 6 had been harvested for timber in previous decades (with large areas of forest removed) while 2 catchments had minimal disturbance (Control catchments). There was no difference in sediment loads from the harvested and Control catchments. The results demonstrate that although land disturbance had previously occurred the management practices employed in each catchment were effective in the long term. This provides confidence that the forest harvesting and subsequent management do not produce detrimental effects in the medium to long term. An assessment of erosion rates and likely soil production rates suggests that the catchments are eroding soil at the rate it is being produced.

  19. 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

  20. 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

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

    PubMed

    Schwesig, D; Matzner, E

    2000-10-09

    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

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  4. 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.

  5. 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.

  6. Influence of topography and forest characteristics on snow distributions in a forested catchment

    NASA Astrophysics Data System (ADS)

    Fujihara, Yoichi; Takase, Keiji; Chono, Shunsuke; Ichion, Eiji; Ogura, Akira; Tanaka, Kenji

    2017-03-01

    Stored water within snowpack is important for the hydrological balance in many mountainous environments around the world. However, monitoring the spatial and temporal dynamics of snow in such mountainous environments remains rather challenging. We therefore developed a snow depth meter using small temperature loggers. Small temperature loggers were attached to poles at 20 cm intervals from the ground surface. Snow depths were estimated by assessing the daily variations in temperatures. Using this snow depth meter, we continuously observed snow depths at 21 stations in a forested catchment in Japan over three winter seasons. Using correlation analysis, we then analyzed the influence of topography (i.e., elevation and aspect) and forest (i.e., canopy openness) on snow depths. Moreover, we estimated daily snow distributions in the area using multi-regression analysis, thus describing seasonal characteristics of snow distributions. Finally we investigated the relation between number of stations and estimation accuracies of snow distributions using a Monte Carlo sensitivity analysis. We observed that the influence of topographical and forest characteristics changed considerably during the study period, with elevation having a major impact on snow depths. Further, aspect and forest cover had a great influence on the snow depths during the melting period. The regression of elevation slopes was 0.8-2.1 mm/m during rich snow years and 0.5-0.6 mm/m in little snow years. Also, the snow distribution during the melting period was found to be less uniform than during the snow accumulation period using histograms of snow depths. Monte Carlo sensitivity analysis shows that one station per 2.0-2.5 ha is enough to estimate accurate snow distributions. Given the above, we concluded that our proposed approach was quite useful for investigating the influence of topography and forest characteristics on snow accumulation and melting.

  7. 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.

  8. 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...

  9. 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,...

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

    NASA Astrophysics Data System (ADS)

    Miller, A. J.; Zegre, N.

    2012-12-01

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

  11. 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

  12. Storage controls on the generation of double peak hydrographs in a forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Martínez-Carreras, Núria; Hissler, Christophe; Gourdol, Laurent; Klaus, Julian; Juilleret, Jérôme; Iffly, Jean François; Pfister, Laurent

    2016-12-01

    Double peak hydrographs are widespread phenomena but poorly understood mechanistically. In many cases, saturation-excess overland flow in the near-stream areas is assumed to control the initial peak, while the delayed peak is explained by subsurface flow in the soil or sediment cover or groundwater flow on fractured bedrock. Here we explore the mechanisms that control the generation of double peak hydrographs in a forested headwater catchment. We made use of the extensive high-resolution hydrometric time series collected in the catchment to estimate catchment storage and causal linkages. We found that double peak hydrographs occurred only after a certain amount of catchment storage was exceeded. The amount of this storage threshold was consistent over a 3-year period. The non-linear relationship between storage and discharge led to hysteretic relationships between both variables, and these hysteretic relationships were different for the different hydrograph types (single or double peak hydrographs). Discharge peaked before catchment storage during single peak hydrographs suggesting that single peaks were mainly generated by water quickly reaching the stream during precipitation pulses. It was catchment storage that peaked first during double peak hydrographs and consequently generated the delayed peak in the hydrograph. Our results also showed that double peak hydrographs were controlled in different proportions by contrasting landscape units (defined along a hillslope sequence). Hillslopes were connected to the stream at low discharge values, whereas the plateau dominated discharge generation when storage reached a certain threshold value.

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  14. 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.

  15. 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

  16. 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...

  17. 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).

  18. 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

  19. Seeps regulate stream nitrate concentration in a forested Appalachian catchment.

    PubMed

    O'Driscoll, Michael A; DeWalle, David R

    2010-01-01

    Surface seeps can be defined as locations where upwelling ground water saturates the surface for most of the year and excess ground water can be delivered to the stream channel via surface flowpaths. If a stream is predominantly fed by seeps, then ground water added to the stream via these surface flowpaths may result in reduced interactions with the subsurface riparian zone. It is generally believed that seep ground water that upwells and then flows along surface flowpaths can be subject to diminished denitrification and biologic uptake processes. Seep effects on stream nitrate (NO(3)) concentration were studied in Baldwin Creek (5.35 km(2)), southwestern Pennsylvania. Nitrate retention within seep zones was evaluated over a 1-yr period (May 2002-2003) using a monthly, nested (top and bottom of seep) sampling approach along 15 individual seeps. Seep samples were analyzed for NO(3)-N, NH(3)-N, and dissolved organic carbon, along with stream waters and streamflow measurements at seven stream stations. Seeps were generally NO(3) sinks with concentrations decreasing downseep: 31% median annual reduction and 73% maximum monthly reduction. During cold and wet periods, seeps frequently behaved as NO(3) sources to the stream (NO(3) concentrations increased or remained constant downseep). Seep temperature and discharge were related to seasonal variability in seep NO(3) retention. Seasonal variations in stream NO(3) concentration have been attributed to upland soil and vegetation processes in numerous watersheds. At Baldwin Creek, seep NO(3) processing regulated the seasonal variability of stream NO(3) concentrations. These results suggest that seeps provide important water quality functions and can modulate the effects of elevated regional N deposition in Appalachian catchments.

  20. 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.

  1. 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

  2. Snow-covered soils produce N2O that is lost from forested catchments

    NASA Astrophysics Data System (ADS)

    Enanga, E. M.; Creed, I. F.; Fairweather, T.; Casson, N. J.

    2016-09-01

    The magnitude of net soil nitrous oxide (N2O) production from a snow-covered catchment in a northern temperate forest was investigated. There was considerable net soil N2O-N production and consumption through the snowpack, ranging from -6.6 to 26.2 g-N ha-1 d-1. There was no difference in net N2O production among topographic positions despite significant variation in soil moisture, reduction-oxidation conditions, and pore water dissolved organic carbon and nitrate. Soil temperatures did not vary among topographic positions, suggesting that temperatures at or above the freezing point allow N2O production to proceed under the snowpack. Redox conditions were lower at wetland positions compared to lowlands and uplands, suggesting that the biogeochemical pathway of N2O production varies with topography. Over the entire nongrowing season, 1.5 kg of N2O-N was exported to the atmosphere from the 6.33 ha catchment, representing 31% of the growing season N2O-N production. These results suggest that winter is an active time for gaseous N production in these forests and that N2O production under the snowpack represents an often unmonitored flux of N from catchments.

  3. 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

  4. 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.

  5. Catchment Hydro-biogeochemical Responses to Forest Harvest Intensity and Spatial Pattern

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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. Specifically, we test for the occurrence of hydrological and biogeochemical threshold behavior in the catchment response. VELMA is a spatially-distributed eco-hydrology model that simulates the effects of climate, and land cover on daily changes in soil water storage, surface and subsurface runoff, vertical drainage, evapotranspiration, vegetation and soil C and N dynamics, and transport of nitrate, ammonium, DON, and DOC to streams. We simulate pre- and post-disturbance hydrological and biogeochemical responses of the WS10 catchment. Model parameters were initialized to simulate the post-fire build-up of ecosystem C and N stocks from 1725 to 1975. These parameters are then fixed and used to simulate the hydro-biogeochemical response after the 1975 clear-cut. Comparison of modeled and observed soil moisture, streamflow, DIN, DON and DOC losses for the post-clear-cut period (1975-2007) show that VELMA accurately captures spatial and temporal dynamics of hydrological and biogeochemical processes in WS10. We then examine the catchment response to alternative clear-cut scenarios for which the location and fraction of harvested area varied. These alternative clear-cut simulations suggest that the streamflow and harvest area relationship in this rain-dominated catchment is nearly linear, irrespective of clear-cut area and location. Simulations designed to identify threshold responses of DOC, DON and DIN export in relation to harvest area and location will be presented.

  6. 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

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Abdelnour, Alex; McKane, Robert; Stieglitz, Marc; Pan, Feifei; Cheng, Yiwei

    2013-03-01

    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 two major disturbance events have occurred during the past 500 years: a stand-replacing fire circa 1525 and a clear-cut in 1975. Hydrological and biogeochemical data from this site and other Pacific Northwest forest ecosystems were used to calibrate the model. Model parameters were first calibrated to simulate the postfire buildup of ecosystem carbon and nitrogen stocks in plants and soil from 1525 to 1969, the year when stream flow and chemistry measurements were begun. Thereafter, the model was used to simulate old-growth (1969-1974) and postharvest (1975-2008) temporal changes in carbon and nitrogen dynamics. VELMA accurately captured observed changes in carbon and nitrogen dynamics before and after harvest. The interaction of hydrological and biogeochemical processes in the model provided a means for interpreting these changes. Results show that (1) losses of dissolved nutrients in the preharvest old-growth forest were generally low and consisted primarily of organic nitrogen and carbon; (2) following harvest, carbon and nitrogen losses from the terrestrial system to the stream and atmosphere increased as a result of reduced plant nitrogen uptake, increased soil organic matter decomposition, and high soil moisture; and (3) the rate of forest regrowth following harvest was lower than that after fire because post-clear-cut stocks and turnover of detritus nitrogen were substantially lower than after fire.

  9. Linking nitrogen cycling and export with variable source area dynamics in forested and urbanizing catchments

    NASA Astrophysics Data System (ADS)

    Band, L. E.; Tague, C. E.; Groffman, P.; Belt, K.

    2001-05-01

    One of the goals of the Baltimore Urban LTER site is to investigate how interactions between ecological processes and urban land use effect ecosystem functions, such as the cycling and export of nutrients. As part of this project, nitrogen export from Pond Branch, a 41 hectare forested catchment in Baltimore County, has been monitored since 1998 and is compared with nitrogen export from neighboring agricultural and urbanizing catchments. To better understand the spatial structure of nitrogen cycling and export processes in this region, a GIS and physically based, hydro-ecological model is used to investigate the interactions between soil water levels, flowpath dynamics and nitrogen cycling and export in Pond Branch. Rates of key ecosystem processes including vegetation uptake, litterfall, decomposition, mineralization, nitrification and denitrification vary in regular spatial and temporal patterns in response to meteorologically driven variations in soil water, temperature and biological activity as well as decadal level variations in canopy composition and extent. Alteration in the distribution of nitrogen sinks and sources in the landscape are particularly manifest in the dynamics of riparian areas that result in peak nitrogen export during the active growing season in this catchment. Urbanization effects can be added to the simulation by altering irrigation and fertilization rates, vegetation patterns and by altering hydrologic flowpaths through the construction of roads and sewer networks. The model is used to investigate current nitrogen cycling and export patterns and scenarios for urbanization of the Pond Branch catchment. Variation in the pattern of land cover change and infrastructure development with respect to the existing pattern of vegetation and topographic controls on nitrogen cycling is shown by the model to influence the impact of urbanization on nitrogen export.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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

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

    NASA Astrophysics Data System (ADS)

    Tada, A.; Tanakamaru, H.

    2007-12-01

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

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

    PubMed

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

    2014-08-15

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

  17. Sulfate exports from multiple catchments in a glaciated forested watershed in western New York, USA.

    PubMed

    Inamdar, Shreeram P; Mitchell, Myron J

    2008-04-01

    Sulfate (SO4(2-)) concentrations and fluxes were studied for multiple storm events in the Point Peter Brook watershed, a glaciated, forested watershed located in Western New York, USA. Investigations were performed across one large (696 ha) and three small (1.6-3.4 ha) catchments with varying extent of riparian and wetland areas. Concentrations of SO4(2-) in groundwater sources (mean values: 238-910 micromol(c) L(-1)) were considerably greater than concentrations recorded for rainfall (60 micromol(c) L(-1)) and throughfall (72-129 micromol(c) L(-1)). Seasonality in SO4(2-) concentrations was most pronounced for valley-bottom riparian waters with maximum concentrations in late winter-spring (February-March) and a minimum in late summer (August). Concentrations of SO4(2-) in wetland water were considerably less than riparian water indicating the likelihood of SO4(2-) reduction in anoxic wetland conditions. Storm events displayed a dilution pattern in SO4(2-) concentrations with a minimum coinciding with the maximum in throughfall contributions. End member mixing analysis (EMMA) was able to predict the storm event concentrations of SO4(2-) for four of the six comparisons. Concentrations of SO4(2-) at the outlet of the large (696 ha) catchment were much greater than values recorded for the smaller catchments. Exports of SO4(2-) in streamflow exceeded the inputs from atmospheric deposition suggesting that watersheds like Point Peter Brook may not show any immediate response to decreases in atmospheric SO4(2-) deposition.

  18. 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.

  19. 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

  20. 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.

  1. Exploring functional similarity in the export of Nitrate-N from forested catchments: A mechanistic modeling approach

    NASA Astrophysics Data System (ADS)

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

    1998-11-01

    Functional similarity of catchments implies that we are able to identify the combination of processes that creates a similar response of a specific characteristic of a catchment. We applied the concept of functional similarity to the export of NO3--N from catchments situated within the Turkey Lakes Watershed, a temperate forest in central Ontario, Canada. Despite the homogeneous nature of the forest, these catchments exhibit substantial variability in the concentrations of NO3--N in discharge waters, over both time and space. We hypothesized that functional similarity in the export of NO3--N can be expressed as a function of topographic complexity as topography regulates both the formation and flushing of NO3--N within the catchment. We tested this hypothesis by exploring whether topographically based similarity indices of the formation and flushing of NO3--N capture the observed export of NO3--N over a set of topographically diverse catchments. For catchments with no elevated base concentrations of NO3--N the similarity indices explained up to 58% of the variance in the export of NO3--N. For catchments with elevated base concentrations of NO3--N, prediction of the export of NO3--N may have been complicated by the fact that hydrology was governed by a two-component till, with an ablation till overlying a basal till. While the similarity indices captured peak NO3--N concentrations exported from shallow flow paths emanating from the ablation till, they did not capture base NO3--N concentrations exported from deep flow paths emanating from the basal till, emphasizing the importance of including shallow and deep flow paths in future similarity indices. The strength of the similarity indices is their potential ability to enable us to discriminate catchments that have visually similar surface characteristics but show distinct NO3--N export responses and, conversely, to group catchments that have visually dissimilar surface characteristics but are functionally similar

  2. 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

  3. 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

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  5. 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.

  6. 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.

  7. 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.

  8. Rain-Induced Bursts Of Nitrous Oxide May Account For Differences In Dissolved Nitrogen Export From Forested Catchments

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Casson, N. J.; Enanga, E.

    2009-05-01

    Despite nearly 30 years of research, we are unable to account for differences in dissolved nitrogen (N) export among catchments in the sugar maple forest of the Turkey Lakes Watershed. Neighboring catchments with similar N inputs show major discrepancies in dissolved N (nitrate + ammonium + dissolved organic nitrogen) export. In this study, we hypothesized that gaseous N export from wetland soils accounts for this discrepancy. To test this hypothesis, soil nitrous oxide (N2O) efflux was measured during the snow free season (May 1 to October 30) in 2006, 2007, and 2008. Minimal N2O efflux (<1 g N/ha/day) was observed on days without rain. However, on days with rain, soil N2O efflux was significant from wetland area soils, with a linear increase of 0.016 g N/ha/day per millimeter of rain (r2 = 0.60, p<0.001); N2O efflux from upland soils was not significant. Process based monitoring of the wetland soil profile suggests that rain delivers water to the surface layers of the wetlands creating an oxygen poor environment where accumulated nitrate is first transformed to N2O and then to dinitrogen (N2). We could not measure N2. However, if we assumed a N2:N2O ratio of 10:1 from the literature, the discrepancy in dissolved N export among the catchments could be explained. Our findings suggest that rain can produce substantial bursts of N2O and N2 from forest soils and that failure to account for gaseous N export may lead to an underestimation of N loss from forested catchments.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. 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.

  13. Assessing colloid-bound metal export in response to short term changes in runoff from a forested catchment

    NASA Astrophysics Data System (ADS)

    Neubauer, E.; Kammer, F. v. d.; Knorr, K.-H.; Pfeiffer, S.; Reichert, M.; Hofmann, T.

    2012-04-01

    Soils can act as a source of metals and natural organic matter (NOM) in runoff from catchments. Amounts and intensity of rainfall may influence NOM export from catchments. The presence of NOM and other colloids in water may not only enhance metal export, but also significantly change metal speciation. In this study, we investigated the response of metal-colloid associations to short-term discharge variations in the runoff from a small forested catchment (Lehstenbach, Bavaria, Germany). Here, the discharge from the catchment outlet responds within hours to rain events. Near-surface flow in organic-rich layers and peat soils has been identified to increase dissolved organic carbon (DOC) concentrations during stormwater runoff. Flow Field-Flow Fractionation coupled to ICP-MS (FlowFFF-ICPMS) is a high-resolution size separation technique which was used for the detection and quantification of colloids and associated metals. Colloid-associated metals, dissolved metals and metals associated with low-molecular weight organic ligands were also separated by filtration (0.2 µm) and ultrafiltration (1000 g/mol MWCO). During baseflow DOC concentration was <6 mg/L and the pH ranged between 4.6 and 5.0. The DOC concentration exported at a given discharge was subject to strong seasonal variation and depended on the water level before the discharge event. DOC concentrations were up to 8 fold higher during stormwater runoff compared to baseflow. The export of aluminum, arsenic, rare earth elements (REE) and uranium from the catchment increased during stormwater runoff showing a strong correlation with NOM concentrations. This result was supported by FlowFFF-ICPMS data revealing that NOM was the only colloid type available for metal complexation during all hydrological conditions. A clear temporal pattern in the association with the NOM was observed for most of the metals under study: During baseflow, 70-100% (Fe), 90% (Al), 60-100% (REE) and 80-85% (U) were associated with the NOM

  14. 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.

  15. 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.

  16. Responses of evapotranspiration at different topographic positions and catchment water balance following a pronounced drought in a mixed species eucalypt forest, Australia

    NASA Astrophysics Data System (ADS)

    Mitchell, Patrick J.; Benyon, Richard G.; Lane, Patrick N. J.

    2012-05-01

    SummaryAcross southern Australia, a large proportion of urban water supply is sourced from mountainous catchments forested with native eucalypts. Mixed species eucalypt forest (MSEF) is the most common forest type in this region and occurs on relatively dry, fire prone sites, yet factors controlling forest water use and stream flow in response to topography, disturbance and drought are poorly understood. This study investigated the patterns and drivers of water balance over a 4 year period in a 1.36 km2, MSEF catchment by: quantifying spatial and temporal variability in evapotranspiration (Et) and its components; evaluating the abiotic, structural and physiological factors controlling water use across the catchment; and testing the effects of antecedent soil water conditions on water fluxes after drought. This was done using a 'bottom up' measurement approach that included stream flow and Et (sap flow, interception troughs and evaporation dome) and a simple empirical model of Et to track catchment response to drought. Spatial variability was considerable, with 40% lower rates of Et at an up slope plot compared to mid and bottom slope plots. Tree transpiration was the dominant flux annually and was correlated to reference Et (r2 = 0.35-0.80), implying strong limitation by atmospheric demand across the catchment. Annual Et totals were relatively consistent between years (841 ± 34 mm) despite large variation in rainfall (463-1179 mm y-1). Annual stream flow represented a very small proportion of the water budget (<2% of rainfall) and showed little recovery from the drought period. The modelling showed that the change in soil water storage following drought was large (up to -330 mm) and was responsible for decreased rates of stream flow. These findings show that Et in the MSEF is sensitive to topography and demand limitation and suggests that water yield in this forest type may be particularly sensitive to future climatic change as shown by the sustained effect of

  17. Long Term Pattern in Runoff Doc Fluxes in Two Boreal Upland Forested Catchments: does the Increasing Nee Affect Doc Fluxes?

    NASA Astrophysics Data System (ADS)

    Pumpanen, J. S.; Lindén, A.; Miettinen, H.; Kolari, P.; Ilvesniemi, H.; Hari, P.; Heinonsalo, J.; Vesala, T.; Back, J. K.; Berninger, F.; Ojala, A.

    2013-12-01

    with NEE (P<0.062) and TER (P<0.056). The annual DOC fluxes were highly correlated in both catchments (correlation coefficients 0.75 and 0.8) with runoff, thus the catchment water balance largely determines the amount of DOC leaving the catchment. In order to get a more comprehensive picture of the long-term trends in the runoff DOC fluxes and their correlation with other ecosystem carbon fluxes, long time series are needed to cover the inter-annual variation in weather conditions. Our results indicate that the DOC concentration, especially in the spring runoff fluxes is increasing, which seems to increase the annual DOC fluxes during wet years, thus decreasing the carbon sinks of upland forest ecosystems and increasing the atmospheric CO2 flux from aquatic ecosystems.

  18. 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

  19. 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...

  20. 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...

  1. 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...

  2. 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.

  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. Exports of dissolved ammonium (NH(4)(+)) during storm events across multiple catchments in a glaciated forested watershed.

    PubMed

    Inamdar, Shreeram

    2007-10-01

    Storm event exports of dissolved NH(4)(+) were explored for multiple events in the Point Peter Brook watershed (PPBW), a glaciated, forested watershed located in Western New York, USA. Investigations were performed across four catchments (1.6-696 ha) with varying topography and the extent of surface-saturated areas. While wetland and riparian waters were important sources of NH(4)(+) during non-storm periods, throughfall and litter leachate were the dominant contributors of NH(4)(+) during storm events. Ammonium concentrations in catchment discharge displayed a sinusoidal seasonal pattern with a maximum during early spring (March) and a minimum in late summer (August-September). Storm event concentrations of NH(4)(+) in streamflow were much greater than baseflow values and showed a consistent temporal pattern with an increase in concentrations on the hydrograph rising limb, a peak at or before the discharge peak, followed by a decline in concentrations. Storm event patterns of DON were similar to NH(4)(+) while the patterns of [Formula: see text]differed from NH(4)(+) for the summer and fall events. The storm event expression of NH(4)(+) was attributed to throughfall and throughfall-mediated leaching of the litter layer. The reactive behavior of NH(4)(+) precluded its use in an end member mixing model (EMMA) for predicting streamflow concentrations. While concentrations of NH(4)(+) in precipitation and streamflow were high for the spring events, exports of NH(4)(+) in streamflow were highest for the large and intense storm events. Baseflow NH(4)(+) concentrations increased with the percent wetland/saturated area in the catchment but the same trend did not hold for storm-event concentrations.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  6. 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. Evaluation of the cosmic-ray neutron method for measuring integral soil moisture dynamics of a forested head water catchment

    NASA Astrophysics Data System (ADS)

    Bogena, H. R.; Metzen, D.; Baatz, R.; Hendricks Franssen, H.; Huisman, J. A.; Montzka, C.; Vereecken, H.

    2011-12-01

    Measurements of low-energy secondary neutron intensity above the soil surface by cosmic-ray soil moisture probes (CRP) can be used to estimate soil moisture content. CRPs utilise the fact that high-energy neutrons initiated by cosmic rays are moderated (slowed to lower energies) most effectively by collisions with hydrogen atoms contained in water molecules in the soil. The conversion of neutron intensity to soil moisture content can potentially be complicated because neutrons are also moderated by aboveground water storage (e.g. vegetation water content, canopy storage of interception). Recently, it was demonstrated experimentally that soil moisture content derived from CRP measurements agrees well with average moisture content from gravimetric soil samples taken within the footprint of the cosmic ray probe, which is proposed to be up to several hundred meters in size [1]. However, the exact extension and shape of the CRP integration footprint is still an open question and it is also unclear how CRP measurements are affected by the soil moisture distribution within the footprint both in horizontal and vertical directions. In this paper, we will take advantage of an extensive wireless soil moisture sensor network covering most of the estimated footprint of the CRP. The network consists of 150 nodes and 900 soil moisture sensors which were installed in the small forested Wüstebach catchment (~27 ha) in the framework of the Transregio32 and the Helmholtz initiative TERENO (Terrestrial Environmental Observatories) [2]. This unique soil moisture data set provides a consistent picture of the hydrological status of the catchment in a high spatial and temporal resolution and thus the opportunity to evaluate the CRP measurements in a rigorous way. We will present first results of the comparison with a specific focus on the sensitivity of the CRP measurements to soil moisture variation in both the horizontal and vertical direction. Furthermore, the influence of forest

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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

  16. Survey of Hylobates agilis albibarbis in a logged peat-swamp forest: Sabangau catchment, Central Kalimantan.

    PubMed

    Buckley, Cara; Nekaris, K A I; Husson, Simon John

    2006-10-01

    Few data are available on gibbon populations in peat-swamp forest. In order to assess the importance of this habitat for gibbon conservation, a population of Hylobates agilis albibarbis was surveyed in the Sabangau peat-swamp forest, Central Kalimantan, Indonesia. This is an area of about 5,500 km(2) of selectively logged peat-swamp forest, which was formally gazetted as a national park during 2005. The study was conducted during June and July 2004 using auditory sampling methods. Five sample areas were selected and each was surveyed for four consecutive days by three teams of researchers at designated listening posts. Researchers recorded compass bearings of, and estimated distances to, singing groups. Nineteen groups were located. Population density is estimated to be 2.16 (+/-0.46) groups/km(2). Sightings occurring either at the listening posts or that were obtained by tracking in on calling groups yielded a mean group size of 3.4 individuals, hence individual gibbon density is estimated to be 7.4 (+/-1.59) individuals/km(2). The density estimates fall at the mid-range of those calculated for other gibbon populations, thus suggesting that peat-swamp forest is an important habitat for gibbon conservation in Borneo. A tentative extrapolation of results suggests a potential gibbon population size of 19,000 individuals within the mixed-swamp forest habitat sub-type in the Sabangau. This represents one of the largest remaining continuous populations of Bornean agile gibbons. The designation of the Sabangau forest as a national park will hopefully address the problem of illegal logging and hunting in the region. Further studies should note any difference in gibbon density post protection.

  17. Evaluation of Load Estimation Methods and Sampling Strategies by Confidence Intervals in Estimating Solute Flux from a Small Forested Catchment

    NASA Astrophysics Data System (ADS)

    Tada, A.; Tanakamaru, H.

    2008-12-01

    Total mass flux (load) from a catchment is a basic factor in evaluating chemical weathering or in TMDLs implementation. So far, many combinations of load estimation methods with sampling strategies were tested to obtain an unbiased flux estimate. To utilize such flux estimates in the political or scientific application, the information of uncertainty of flux estimates should also be provided. Giving the interval estimate of total flux may be a desirable solution to this situation. Total solute flux from a small, undisturbed forested catchment (12.8ha) during 10 months were calculated based on high-temporal resolution data and used in validation of 95% confidence intervals (CIs) of flux estimates. Water quality data (sodium, potassium, and chloride concentration) were collected and measured every 15 minutes during 10 months in 2004 by the on-site monitoring system using FIP (flow injection potentiometry) method with ion-selective electrodes. Water quantity data (the flow rate data) were measured continuously by V-notch weir at the catchment outlet. Flux estimates and 95% CIs were calculated for three indices with 41 methods; sample average, flow- weighted average, the Beale ratio estimator, rating curve method with simple linear regression between flux and the flow rate, and nine regression models in the USGS Load Estimator (Loadest). Smearing estimates, MVUE estimates, and estimates by composite method were also evaluated concerning nine regression models in Load Estimator. Two sampling strategies were tested; periodical sampling (daily and weekly) and flow stratified sampling. After data were sorted in ascending order of the flow rate, five strata were configured so that each stratum contained same number of data in flow stratified sampling. The performance of these 95% CIs was evaluated by the rate of inclusion of true flux value within these CIs, which should be expected as 0.95. A simple bootstrap method was adopted to construct the CIs with 2,000 bootstrap

  18. 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.

  19. An ordination of the forest communities in Nainital catchment of Kumaun Himalaya.

    PubMed

    Kharkwal, Geeta; Rawat, Yashwant Singh; Pangtey, Yashpal Singh

    2009-09-01

    Evergreen forest communities distributed within 1580-2600 m above sea level (asl) in Kumaun Himalaya were studied. Quercus leucotrichophora A. Campus, Q. floribunda Lindl. ex Rehder Q. semecarpifolia J.E. Smith and Pinus roxburghii Sarg. are the dominant tree species in banj-oak, tilonj-oak, kharsu-oak and chir-pine forests, respectively. Total density for tree, shrub and herb layer varied from 3.7 to 10.5 (individual 100 m(-2)), 2.0 to 38.8 (individual 100 m(-2)) and 5.5 to 44.0 (individual m(-2)), respectively. A total of five forests types (27 stands) were identified in the field on the basis of species richness and species diversity by applying polar ordination method. The diversity value fortree, shrub and herb layer ranged from 0 to 3.62, 0.36 to 3.85 and 1.23 to 4.21, respectively. Present study indicates the spatial patterns of vegetation in different forest communities at different altitudes.

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

    NASA Astrophysics Data System (ADS)

    James, April L.; Roulet, Nigel T.

    2006-08-01

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

  1. Using the INCA-Hg model of mercury cycling to simulate total and methyl mercury concentrations in forest streams and catchments.

    PubMed

    Futter, M N; Poste, A E; Butterfield, D; Dillon, P J; Whitehead, P G; Dastoor, A P; Lean, D R S

    2012-05-01

    We present a new, catchment-scale, process-based dynamic model for simulating mercury (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 (Hg(0)), ionic (Hg(II)) and methyl (MeHg) Hg 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 we believe control surface water Hg dynamics. The model simulates daily time series between one and 100 years long and can be applied to catchments ranging in size from <1 to ~10,000 km(2). Here we present applications of the model to two boreal forest headwater catchments in central Canada where we were able to reproduce observed patterns of stream water total mercury (THg) and MeHg fluxes and concentrations. Model performance was assessed using Monte Carlo techniques. Simulated in-stream THg and MeHg concentrations were sensitive to hydrologic controls and terrestrial and aquatic process rates.

  2. Modeling watershed-scale (137)Cs transport in a forested catchment affected by the Fukushima Dai-ichi Nuclear Power Plant accident.

    PubMed

    Wei, Lezhang; Kinouchi, Tsuyoshi; Yoshimura, Kazuya; Velleux, Mark L

    2017-02-02

    The Fukushima nuclear accident in 2011 resulted in (137)Cs contamination of large areas in northeast Japan. A watershed-scale (137)Cs transport model was developed and applied to a forested catchment in Fukushima area. This model considers (137)Cs wash-off from vegetation, movement through soils, and transport of dissolved and particulate (137)Cs adsorbed to clay, silt and sand. Comparisons between measurements and simulations demonstrated that the model well reproduced (137)Cs concentrations in the stream fed from the catchment. Simulations estimated that 0.57 TBq of (137)Cs was exported from the catchment between June, 2011 and December, 2014. Transport largely occurred with eroded sediment particles at a ratio of 17:70:13 of clay, silt, and sand. The overall (137)Cs reduction ratio by rainfall-runoff wash-off was about 1.6%. Appreciable (137)Cs remained in the catchment at the end of 2014. The largest rate of (137)Cs reduction by wash-off was simulated to occur in subwatersheds of the upper catchment. However, despite relatively low initial deposition, middle portions of the watershed exported proportionately more (137)Cs by rainfall-runoff processes. Simulations indicated that much of the transported (137)Cs originates from erosion over hillsides and river banks. These results suggested that areas where (137)Cs accumulates with redeposited sediments can be targeted for decontamination and also provided insight into (137)Cs transport at the watershed scale to assess risk management and decontamination planning efforts.

  3. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  4. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 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...

  5. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  6. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 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...

  7. 7 CFR 58.720 - Acidifying agents.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 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...

  8. Effects of pipeflow on hydrological process and its relation to landslide: a review of pipeflow studies in forested headwater catchments

    NASA Astrophysics Data System (ADS)

    Uchida, Taro; Kosugi, Ken'ichirou; Mizuyama, Takahisa

    2001-08-01

    Since the 1980s, several field studies of pipeflow hydrology have been conducted in forested, steep headwater catchments. However, adequate information is lacking with regard to questions as to how representative these previous studies are and how widespread the phenomena might be. Thus, the aim of this study is to review some studies of pipeflow hydrology on forested steep hillslopes. Several points were clarified. (1) The maximum discharge of pipeflow was mainly determined by the soil pipe diameter. When the condition of both the soil pipe diameter and the slope gradient in forest soil were similar to those in peaty podzol, the maximum discharge of pipeflow on forest slopes was slighter than that in peaty podzol. (2) Pipeflow was delivered from a variety of sources, and the contributing area of pipeflow extended as the soil layer became wetter. Therefore, the dominant contributor (new water and old water) was varied and the contribution of pipeflow to streamflow increased with the increase of rainfall magnitude. (3) The roles of pipeflow in the storm runoff generation processes demonstrated two roles: the concentration of water and the rapid drainage to downslopes. Thus, soil pipes can increase the peak discharge from the hillslope and decrease the peak lag time of the storm hydrograph, when compared to the unpiped hillslope. (4) The roles of pipeflow on hydrological process suggested that the soil pipes contribute to the slope stability by increasing the rate of soil drainage and limiting the development of perched groundwater conditions. However, if the rate of water concentration to the soil pipe network is in excess of the pipeflow transmission capacity, the cavity of the soil pipe could readily be filled with water during a rain event, increasing pore water pressure in the surrounding matrix. In this case, the soil pipe induced slope instability. (5) Moreover, pipe erosion has significant impact on the runoff characteristics of pipeflow, since pipe erosion

  9. 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.

  10. Isotopic evidence for determining the sources of dissolved organic sulfur in a forested catchment.

    PubMed

    Kang, Phil-Goo; Mitchell, Myron J; Mayer, Bernhard; Campbell, John L

    2014-10-07

    Understanding sulfur (S) biogeochemistry, especially in those watersheds subject to elevated levels of atmospheric S inputs, is needed for determining the factors that contribute to acidification, nutrient losses and the mobilization of toxic solutes (e.g., monomeric aluminum and methylmercury). S is found in a variety of both organic and inorganic forms undergoing a range of biotic and abiotic transformations. In watersheds with decreasing atmospheric S inputs, internal cycling is becoming dominant in affecting whether there is net loss or retention of S. Little attention has been given to the role of dissolved organic S (DOS) in affecting S biogeochemistry. DOS originates from assimilatory and bacterial dissimilatory S reduction (BDSR), the latter of which produces (34)S-depleted S. Within groundwater of the Archer Creek Catchment in the Adirondack Mountains (New York) there was reoxidation of reduced S, which was an important source of SO4(2-). DOS in surface waters had a higher variation of δ(34)S-DOS values (-6.0 to +8.4‰) than inorganic S with δ(34)S-SO4(2-) values ranging from +1.0 to +5.8‰. Inverse correlations between δ(34)S values of SO4(2-) and DOS suggested that BDSR played an important role in producing DOS.

  11. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  12. 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...

  13. 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...

  14. 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.

  15. Nitrogen, phosphorus, carbon, and suspended solids loads from forest clear-cutting and site preparation: long-term paired catchment studies from eastern Finland.

    PubMed

    Palviainen, Marjo; Finér, Leena; Laurén, Ari; Launiainen, Samuli; Piirainen, Sirpa; Mattsson, Tuija; Starr, Mike

    2014-03-01

    The long-term impacts of current forest management methods on surface water quality in Fennoscandia are largely unexplored. We studied the long-term effects of clear-cutting and site preparation on runoff and the export of total nitrogen (total N), total organic nitrogen (TON), ammonium (NH(4)-N), nitrate (NO(3)-N), total phosphorus (total P), phosphate (PO(4)-P), total organic carbon, and suspended solids (SS) in three paired-catchments in Eastern Finland. Clear-cutting and soil preparation were carried out on 34 % (C34), 11 % (C11), and 8 % (C8) of the area of the treated catchments and wide buffer zones were left along the streams. Clear-cutting and soil preparation increased annual runoff and total N, TON, NO(3)-N, PO(4)-P, and SS loads, except for SS, only in C34. Runoff increased by 16 % and the annual exports of total N, TON, NO(3)-N, and PO(4)-P by 18, 12, 270, and 12 %, respectively, during the 14-year period after clear-cutting. SS export increased by 291 % in C34, 134 % in C11, and 16 % in C8 during the 14, 6, and 11-year periods after clear-cutting. In the C11 catchment, NO(3)-N export decreased by 12 %. The results indicate that while current forest management practices can increase the export of N, P and SS from boreal catchments for many years (>10 years), the increases are only significant when the area of clear cutting exceeds 30 % of catchment area.

  16. Estimating Loads from a Small Forested Catchment; An Evaluation Based on High-frequency Water Quality Data

    NASA Astrophysics Data System (ADS)

    Tada, A.; Kuribayashi, Y.; Tanakamaru, H.

    2013-12-01

    Uncertainty in estimating loads from a catchment is always a bothersome problem in the evaluation of anthropogenic impacts on the water environment. Many researchers suggested improved formulas for load calculation and sampling strategies for unbiased load estimates. However, convincing, comprehensive and well-tested load estimation method doesn't exist yet due to the lack of water quality data with high-frequency because an approximate estimate of 'true' load is essential in evaluating its uncertainty. Selection At List Time (SALT) method is one of the comprehensive unbiased load estimation methods and it was introduced by Thomas in 1985. Indeed, it was the application of importance sampling (IS) method for load estimation. This method would be expected to bring an unbiased load estimate theoretically. For the establishment of unbiased loads estimation method, the uncertainty of load estimates with IS methods was evaluated based on suspended solids (SS) concentration data with 10 minute interval from 2011 to 2012 (about 12 months with 97% undetected concentration), three solutes data (sodium, potassium and chloride) with 15 minute interval from 2009 to 2011 (about 23 months with 20 to 30% of missing data) and 10 minutes resolution discharge data from a small forested catchment (12.82ha) in Nara, JAPAN. The ordinary rating curve (power law type) was adopted in the approximation of the loading population. An evaluation of unbiasedness of the load estimate was done using coverage rates of 95% confidence intervals using the bootstrap method. The results showed reasonable performance of 95% C.I.s when the sample size was larger than 50 and robustness of the IS method. For example, coverage rate of 95% C.I.s for solutes varies from 92 to 96 % when the 60 to 570 samples were used to estimate the loads. Biases in load estimates with a smaller number of samples (less than 50) were also recognized when the variance of residuals is large (e.g. >1.0) on a log scale

  17. Evaluating Hydrologic Responses to Climate Changes in an Inland Pacific Northwest Forested Headwater Catchment by Using Numerical Modeling (Invited)

    NASA Astrophysics Data System (ADS)

    Du, E.; Link, T. E.; Abatzoglou, J. T.

    2010-12-01

    The hydrology of the interior Pacific Northwest (PNW) is dominated by seasonal snowmelt from forested uplands. Hydrologic regimes in the area are vulnerable to climate change as many catchments contain large areas that are located within or above the transient snow zone. Hydrologic regime shifts may result from warmer temperatures that may increase the rain to snow ratio of winter precipitation. This is of concern because as snowpack declines, more runoff occurs earlier in the winter and therefore may increase the interval between the major seasonal runoff and the timing of water resource needs. Warmer temperatures may also increase evaporation and transpiration and extend the seasonal drought in the region. We assessed potential future hydrologic changes in the Mica Creek Experimental Watershed (MCEW), a mountainous headwater catchment in northern Idaho, using data from an ensemble of 12 downscaled general circulation models (GCM) based on the IPCC A1B greenhouse gas emission scenario. The data were used to drive the physically based, spatially explicit Distributed Hydrology Soil Vegetation Model (DHSVM) to estimate future flow regimes. The simulation results indicate that seasonal snowpack in this snow-dominated watershed almost completely disappears by 2046 with corresponding mean annual temperature increases of 2.7-4.7 C and annual precipitation stays almost the same. Compared to the 1981-2000 time period, evaporative fluxes are predicted to increase by 9-63% in 2046-2065, most of which occurs during the winter months. Annual water yield predictions in 2046-2065 range from 55% to 100% of the current value. The streamflow simulations suggest large seasonal flow changes; winter runoff (October-March) increases by 44 to 183%, whereas spring and summer runoff (April -September) declines by 23 to 70%. The simulations suggest that the annual hydrograph centroid is expected to advance by 17 to 73 days, and that seasonal peakflows should decrease and shift from May to

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    USGS Publications Warehouse

    Rice, Karen C.; Hornberger, George 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.

  1. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. 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.

  4. Modelling the impact of riparian forest changes on daily sediment yield: A case study in a meso-scale catchment in SE Germany.

    NASA Astrophysics Data System (ADS)

    Keesstra, Saskia; Temme, Arnaud; Feger, Karl-Heinz; van Miltenburg, Saskia

    2010-05-01

    The newly developed sediment delivery model LAPSUS-D has been tested in the meso-scale catchment (60km2) of the Wilde Weisseritz in South-East Germany. LAPSUS-D is the first sediment delivery model that runs with a daily time step and only uses the following input parameters: a DEM, a land use map, a soil map and daily precipitation and discharge data. As the model is new and was calibrated only for a catchment in South-West Poland, the model is now run simultaneous with a widely used sediment delivery model WaTEM/SEDEM (developed in Leuven, Belgium) which simulates erosion and deposition processes on a yearly basis. After a first assessment of the model performance in the German catchment, two scenarios to reduce the sediment yield at the outlet were run. The scenarios were made based on actual river restoration projects elsewhere in similar river settings, to make the scenarios a realistic option for the future. These scenarios were used to run both models to test how the new LAPSUS-D model performs. The comparison reveals the contrast between a yearly and RUSLE based model and the water balance model LAPSUS-D using daily input. The water balance approach includes the effects of the water storage capacity. Locally decreasing water storage capacity causes increased run-off and erosion at lower positions in the landscape. This effect is not visible with the RUSLE approach. Furthermore, the position of the riparian forest scenarios results in differences in the sediment yield simulated by the LAPSUS-D model. While modeling the riparian forest scenarios at different locations in the catchment by the WaTEM/SEDEM causes no difference in sedimentation yield.

  5. Spatial and temporal variations in the effects of soil depth and topographic wetness index of bedrock topography on subsurface saturation generation in a steep natural forested headwater catchment

    NASA Astrophysics Data System (ADS)

    Liang, Wei-Li; Chan, Meng-Chun

    2017-03-01

    Subsurface saturation near the bedrock surface is an important source of runoff generation and deeper bedrock recharge. While many studies have reported the generation patterns of subsurface saturation on valley side slopes or unchanneled catchments, studies focusing on the relationship between bedrock topography and subsurface saturation dynamics in a headwater catchment are still rare. This study therefore analyzed the effects of bedrock topographic features on subsurface saturation generation based on a dataset of pore water pressure (ψ) observations at the soil-bedrock interface and the spatial distributions of soil depth and the topographic wetness index (TWI) of bedrock topography in a steep natural forested headwater catchment. Temporal variations in the mean and standard deviation of ψ were lower at the perennially saturated points but higher at the ephemerally saturated points. The expansion patterns of subsurface saturation during storm events could be classified into four stages: fragmentary and unconnected distributions, both downward and upward expansions, interconnection from upslope to downslope, and disappearance from the middle slope. When saturation was interconnected, 41% of accumulated rainfall contributed to increases of subsurface saturation with a highly linear relationship. Soil depth correlated negatively with the increase in ψ at all points and at ephemerally saturated points. These negative correlations occurred frequently after the generation of new saturation, and remained for a short period around the early peaks of rainfall when the mean of ψ increased sharply. TWI correlated positively with ψ and ψ ⩾ 0 among all points but not in the subsets of perennially or ephemerally saturated points. The positive correlations became more significant after generation of new saturation. Overall, this study demonstrates that the effects of soil depth and TWI on subsurface saturation vary with space and time in a steep natural forested

  6. Spatial distribution of soil structure in a suburban forest catchment and its effect on spatio-temporal soil moisture and runoff fluctuations

    NASA Astrophysics Data System (ADS)

    Maeda, Kenji; Tanaka, Takafumi; Park, Hotaek; Hattori, Shigeaki

    2006-04-01

    Intensive hydrological observations and model calculations reveal that heterogeneous distributions of soil thickness and soil physical characteristics greatly influence long-term spatio-temporal fluctuations of soil moisture and runoff in a suburban forest, which has rich (thickly wooded) forest but undeveloped forest soil. This paper presents a simple, physical-contour-based model that can describe topography and spatially heterogeneous distributions, and uses the model to clarify how spatial heterogeneous variability influences long-term rainfall runoff processes. The 1.5-ha study catchment features deciduous-evergreen secondary forest and is located near an urban area about 30 km southeast of Nagoya City, in central Japan. This model can simulate saturated/unsaturated throughflow, excess flow, and soil moisture, and has not been calibrated. No input parameters have been fitted and all input parameters are based on published and measured data. Rainfall runoff processes are affected by structural distributions of colluvial/residual soil and spatial heterogeneous distributions of soil thickness. The heterogeneous soil thickness distribution contributes, in particular, to headwater conservation, which moderates storm flow and inhibits drought water flow. The magnitude of headwater conservation and the alignment of individual hillslope elements help to control runoff. The mechanism is attributable to the greater degree of headwater conservation in a suburban forest compared with a homogeneous natural forest. The model also clarifies and predicts water circulation on a larger scale than has been possible to date.

  7. 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

  8. 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

  9. 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

  10. 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,...

  11. 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,...

  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. 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

  15. 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

  16. Contrasting transit times of water from peatlands and eucalypt forests in the Australian Alps determined by tritium: implications for vulnerability and the source of water in upland catchments

    NASA Astrophysics Data System (ADS)

    Cartwright, Ian; Morgenstern, Uwe

    2016-12-01

    Peatlands are a distinctive and important component of many upland regions that commonly contain distinctive flora and fauna which are different from those of adjacent forests and grasslands. Peatlands also represent a significant long-term store of organic carbon. While their environmental importance has long since been recognised, water transit times within peatlands are not well understood. This study uses tritium (3H) to estimate the mean transit times of water from peatlands and from adjacent gullies that contain eucalypt forests in the Victorian Alps (Australia). The 3H activities of the peatland water range from 2.7 to 3.3 tritium units (TUs), which overlap the measured (2.9 to 3.0 TU) and expected (2.8 to 3.2 TU) average 3H activities of rainfall in this region. Even accounting for seasonal recharge by rainfall with higher 3H activities, the mean transit times of the peatland waters are < 6.5 years and may be less than 2 years. Water from adjacent eucalypt forest streams has 3H activities of 1.6 to 2.1 TU, implying much longer mean transit times of 5 to 29 years. Cation / Cl and Si / Cl ratios are higher in the eucalypt forest streams than the peatland waters and both of these water stores have higher cation / Cl and Si / Cl ratios than rainfall. The major ion geochemistry reflects the degree of silicate weathering in these catchments that is controlled by both transit times and aquifer lithology. The short transit times imply that, unlike the eucalypt forests, the peatlands do not represent a long-lived store of water for the local river systems. Additionally, the peatlands are susceptible to drying out during drought, which renders them vulnerable to damage by the periodic bushfires that occur in this region.

  17. 21 CFR 131.111 - Acidified milk.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.111 Acidified milk. (a... ingredients. Cream, milk, partially skimmed milk, or skim milk, used alone or in combination. (d)...

  18. 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.

  19. Effects of the "Conversion of Cropland to Forest and Grassland Program" on the water budget of the Jinghe River catchment in China.

    PubMed

    Qiu, Guo Yu; Yin, Jing; Tian, Fei; Geng, Shu

    2011-01-01

    In 1999 China adopted the "Conversion of Cropland to Forest and Grassland Program" (CCFGP), a nationwide ecological recovery program, to minimize wide-scale soil erosion and vegetation degradation in China, as well as to improve water budgeting results. In the 10 yr since implementation, the CCFGP has resulted in the recovery and reforestation of >100,000 km of cropland and bare land, though the quantitative effect of this program on catchment water budget is not entirely clear. Therefore, we used the Soil and Water Assessment Tool to evaluate and quantify the effects of the CCFGP on the water budget of the Jinghe River catchment, a tributary of the Yellow River covering the central region of the Loess Plateau. Our results indicated that precipitation had dropped by 12.0% from the 1970s (611.6 mm) to the 2000s (538 mm) and that there was a corresponding 25.2% decrease in humidity index from 0.48 to 0.36. Before the CCFGP's implementation, forest and grassland had been decreasing, while bare land, cropland, and shrub land had been increasing. After the implementation of the CCFGP, the opposite trend was observed. Moreover, streamflow increased by about 15 and 20% for the upstream and middle stream subbasins, respectively, while soil water content also showed an obvious increase. Over the same period, evapotranspiration decreased by 5.2 and 13.5 mm and runoff decreased by 37.5 and 38.6% in the two subbasins. The same trends were obtained in the downstream subbasin, where changes were even greater. As a result of the reduced runoff and evapotranspiration, utilization of water resources was more efficient and ecological environment was improved under the CCFGP policy. Our results indicate the CCFGP resulted in a favorable ecological impact and should therefore be maintained.

  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. Effects of lateral nitrate flux and instream processes on dissolved inorganic nitrogen export in a forested catchment: A model sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Lin, Laurence; Webster, Jackson R.; Hwang, Taehee; Band, Lawrence E.

    2015-04-01

    The importance of terrestrial and aquatic ecosystems in controlling nitrogen dynamics in streams is a key interest of ecologists studying dissolved inorganic nitrogen (DIN) export from watersheds. In this study, we coupled a stream model with a terrestrial ecohydrological model and conducted a global sensitivity analysis to evaluate the relative importance of both ecosystems to nitrogen export. We constructed two scenarios ("normal" and high nitrate loads) to explore conditions under which terrestrial (lateral nitrate flux) or aquatic ecosystems (instream nutrient processes) may be more important in controlling DIN export. In a forest catchment, although the forest ecosystem controls the nitrogen load to streams, sensitivity results suggested that most nitrogen output from the terrestrial ecosystem was taken up by instream microbial immobilization associated with benthic detritus and retained in detritus. Later the immobilized nitrogen was remineralized as DIN. Therefore, the intra-annual pattern of DIN concentration in the stream was low in fall and became high in spring. Not only was instream microbial immobilization saturated with the high nitrogen load scenario, but also the net effect of immobilization and mineralization on DIN export was minimized because nitrogen cycling between organic and inorganic forms was accelerated. Overall, our linked terrestrial-aquatic model simulations demonstrated that stream process could significantly affect the amount and timing of watershed nitrogen export when nitrogen export from the terrestrial system is low. However, when nitrogen export from the terrestrial system is high, the effect of stream processes is minimal.

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 21 CFR 108.25 - Acidified foods.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN..., or packing of acidified foods may result in the distribution in interstate commerce of processed... after these foods have entered into interstate commerce. The Commissioner of Food and Drugs...

  7. 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)).

  8. 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

  9. 21 CFR 173.325 - Acidified sodium chlorite solutions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN CONSUMPTION Specific Usage Additives § 173.325 Acidified sodium chlorite solutions. Acidified...., College Park, MD 20740, or may be examined at the Center for Food Safety and Applied Nutrition's...

  10. 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

  11. 21 CFR 173.325 - Acidified sodium chlorite solutions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acidified sodium chlorite solutions. 173.325... HUMAN CONSUMPTION Specific Usage Additives § 173.325 Acidified sodium chlorite solutions. Acidified sodium chlorite solutions may be safely used in accordance with the following prescribed conditions:...

  12. 21 CFR 173.325 - Acidified sodium chlorite solutions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acidified sodium chlorite solutions. 173.325... HUMAN CONSUMPTION Specific Usage Additives § 173.325 Acidified sodium chlorite solutions. Acidified sodium chlorite solutions may be safely used in accordance with the following prescribed conditions:...

  13. 21 CFR 173.325 - Acidified sodium chlorite solutions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acidified sodium chlorite solutions. 173.325... § 173.325 Acidified sodium chlorite solutions. Acidified sodium chlorite solutions may be safely used in... solution of sodium chlorite (CAS Reg. No. 7758-19-2) with any generally recognized as safe (GRAS) acid....

  14. 21 CFR 131.162 - Acidified sour cream.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Acidified sour cream. 131.162 Section 131.162 Food... HUMAN CONSUMPTION MILK AND CREAM Requirements for Specific Standardized Milk and Cream § 131.162 Acidified sour cream. (a) Description. Acidified sour cream results from the souring of pasteurized...

  15. 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...

  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. 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

  18. Analysis of methane production pathways in a riparian wetland of a temperate forest catchment, using δ13C of pore water CH4 and CO2

    NASA Astrophysics Data System (ADS)

    Itoh, Masayuki; Ohte, Nobuhito; Koba, Keisuke; Sugimoto, Atsuko; Tani, Makoto

    2008-09-01

    To clarify how hydrological processes affect biogenic methane (CH4) production and emission from soil surfaces, we analyzed the δ13C of CH4 and CO2 and chemical constituents dissolved in groundwater at a wetland in the headwater catchment of a temperate forest in Japan. We estimated the contribution of acetate fermentation using the δ13C isotope mass balance of dissolved CH4 and CO2. CH4 production pathways (e.g., acetate fermentation and carbonate reduction) changed temporally and spatially with hydrologically controlled redox conditions. The proportion of methanogenesis attributable to acetate fermentation usually decreased with temperature, suggesting that carbonate reduction dominated under conditions of high CO2 concentration. In particular, the groundwater table and summer temperatures were key controlling factors in the interannual and intra-annual changes in CH4 production pathways, controlling oxygen supply and consumption and, therefore, redox conditions in the soil. Under high temperature and high water table conditions during summer, the soil was strongly reduced and the proportion of carbonate reduction increased. Acetate fermentation also increased episodically, resulting in sporadic increases in δ13C-CH4. The calculated acetate contribution obviously decreased in periods of low water table and high temperature when the soil surface was relatively oxic, implying deactivation of acetoclastic methanogenesis under oxic conditions. Thus, hydrological processes control the supply of these electron donors and acceptors and therefore play an important role in determining the relative proportions of CH4-producing pathways. Our results also indicate that an increase in acetate contribution under highly reducing conditions stimulates CH4 production and emission from the soil surface.

  19. 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

  20. 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

  1. B-complex vitamins in cultured and acidified yogurt.

    PubMed

    Reddy, K P; Shahani, K M; Kulkarni, S M

    1976-02-01

    Studies were to determine the effect of various factors upon B-vitamin content of cultured yogurt and to compare the B-vitamin contents of cultured and direct acidified yogurt. Incubation of yogurt culture at 42 C for 3 h yielded maximum vitamin synthesis concurrent with optimal flavor and texture qualities. A method was standardized for the manufacture of direct acidified yogurt involving the use of Stabilac acidulant and nonfat dry milk, Carboxymethyl cellulose, gelatin, and Starite. Acidified yogurt showed a slightly higher content of certain B-vitamins than the cultured yogurt due to the contribution made by various food additives. Both cultured and acidified yogurt showed good keeping quality and freedom from microbial contaminants during storage at 5 C for 16 days. However, folic acid and vitamin B12 contents decreased 29 and 60% in cultured yogurt and 48 and 54% in acidified yogurt.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. In Lieu of the Paired-Catchment Approach - Hydrologic Model Change Detection at the Catchment Scale

    NASA Astrophysics Data System (ADS)

    Zegre, N. P.

    2009-05-01

    Knowledge of the effects of forest management on hydrology primarily comes from paired-catchment studies conducted world-wide. While this approach has been useful for discerning changes in small experimental catchments and has contributed fundamental knowledge of the effects of forest and natural resources management on hydrology, results from experimental catchment studies exhibit temporal variability, have limited spatial inference, and lack insight into internal catchment processes. To address these limitations, traditional field experiments can be supplemented with numerical models to isolate the effects of disturbance on catchment behavior. Outlined in this study is an alternative method of change detection for daily time-series streamflow that integrates hydrologic modeling and statistical change detection methods used to discern the effects of contemporary forest management on the hydrology of western Oregon Cascades headwater catchments. In this study, a simple rainfall-runoff model was used to generate virtual reference catchments using attributes that reflect streamflow conditions absent of forest disturbance. Streamflow was simulated under three levels of model uncertainty using GLUE and were used to construct generalized least squares regression models to discern changes in hydrologic behavior. By considering processes within a single experimental catchment rather than the two spatially explicit catchments used in traditional paired experiments, it was possible to reduce unexplained variation and increase the likelihood of correctly detecting hydrologic effects following forest harvesting. In order to evaluate the stability of the hydrologic and statistical models and catchment behavior over time, the change detection method was applied to a contemporary reference catchment. By applying the change detection model to reference catchments, it was possible to eliminate unexpected variation as a cause for detected changes in observed hydrology. Further, it

  4. Elevated aluminium concentration in acidified headwater streams lowers aquatic hyphomycete diversity and impairs leaf-litter breakdown.

    PubMed

    Baudoin, J M; Guérold, F; Felten, V; Chauvet, E; Wagner, P; Rousselle, P

    2008-08-01

    Aquatic hyphomycetes play an essential role in the decomposition of allochthonous organic matter which is a fundamental process driving the functioning of forested headwater streams. We studied the effect of anthropogenic acidification on aquatic hyphomycetes associated with decaying leaves of Fagus sylvatica in six forested headwater streams (pH range, 4.3-7.1). Non-metric multidimensional scaling revealed marked differences in aquatic hyphomycete assemblages between acidified and reference streams. We found strong relationships between aquatic hyphomycete richness and mean Al concentration (r = -0.998, p < 0.0001) and mean pH (r = 0.962, p < 0.002), meaning that fungal diversity was severely depleted in acidified streams. By contrast, mean fungal biomass was not related to acidity. Leaf breakdown rate was drastically reduced under acidic conditions raising the issue of whether the functioning of headwater ecosystems could be impaired by a loss of aquatic hyphomycete species.

  5. Schwertmannite stability in acidified coastal environments

    NASA Astrophysics Data System (ADS)

    Collins, Richard N.; Jones, Adele M.; Waite, T. David

    2010-01-01

    A combination of analytical and field measurements has been used to probe the speciation and cycling of iron in coastal lowland acid sulfate soils. Iron K-edge EXAFS spectroscopy demonstrated that schwertmannite dominated (43-77%) secondary iron mineralization throughout the oxidized and acidified soil profile, while pyrite and illite were the major iron-bearing minerals in the reduced potential acid sulfate soil layers. Analyses of contemporary precipitates from shallow acid sulfate soil groundwaters indicated that 2-line ferrihydrite, in addition to schwertmannite, is presently controlling secondary Fe(III) mineralization. Although aqueous pH values and concentrations of Fe(II) were seasonally high, no evidence was obtained for the Fe(II)-catalyzed crystallization of either mineral to goethite. The results of this study indicate that: (a) schwertmannite is likely to persist in coastal lowland acid sulfate soils on a much longer time-scale than predicted by laboratory experiments; (b) this mineral is less reactive in these types of soils due to surface-site coverage by components such as silicate and possibly, to a lesser extent, natural organic matter and phosphate and; (c) active water table management to promote oxic/anoxic cycles around the Fe(II)-Fe(III) redox couple, or reflooding of these soils, will be ineffective in promoting the Fe(II)-catalyzed transformation of either schwertmannite or 2-line ferrihydrite to crystalline iron oxyhydroxides.

  6. 75 FR 59268 - Draft Guidance for Industry: Acidified Foods; Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-27

    ... and in employing appropriate quality control procedures. Under the draft guidance, processors of non... safe manufacturing, processing, and packing processes and in employing appropriate quality control... Establishment-Specific Written Quality Control Plans and Recordkeeping for Acidified Foods, and...

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  13. Seasonal cycles of dissolved constituents in streamwater in two forested catchments in the mid-Atlantic region of the eastern U.S.A.

    USGS Publications Warehouse

    Rice, Karen C.; Bricker, Owen P.

    1995-01-01

    Streamwater discharge and chemistry of two small catchments on Catoctin Mountain in north-central Maryland have been monitored since 1982. Repetitive seasonal cycles in stream-water chemistry have been observed each year, along with seasonal cycles in the volume of stream discharge and in groundwater levels. The hypothesis that the observed streamwater chemical cycles are related to seasonal changes in the hydrological flow paths that contribute to streamflow is examined using a combination of data on groundwater levels, shallow and deep groundwater chemistry, streamwater discharge, streamwater chemistry, soil-water chemistry, and estimates of water residence times. The concentrations of constituents derived from rock weathering, particularly bicarbonate and silica, increase in streamwater during the summer when the water table is below the regolith-bedrock interface and stream discharge consists primarily of deep groundwater from the fractured-bedrock aquifer. Conversely, the concentrations in streamwater of atmospherically derived components, particularly sulfate, increase in winter when the water table is above the regolith-bedrock interface and stream discharge consists primarily of shallow groundwater from the regolith. Tritium and chlorofluorocarbon (CFC) measurements suggest that the groundwater in these systems is young, with a residence time of less than several years. The results of this study have implications for the design of large-scale water-quality monitoring programs.

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

    PubMed

    Jeison, D; van Lier, J B

    2007-09-01

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

  15. 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

  16. The natural rehabilitation of an anthropogenically acidified tropical Lake: two decades of monitoring.

    PubMed

    Araújo, Cristiano V M; Cohin-de-Pinho, Salomão J; Chastinet, Carla B A; Machado, Sandro L; da Silva, Eduardo M

    2013-01-01

    The rehabilitation of a pond after approximately 20 years of strong acidified conditions due to industrial and domestic waste deposition in its catchment basin is reviewed. We describe in this study the acidification process that occurred in a tropical pond in Northeast Brazil (Dunas Lake), the rehabilitation plan for the pond and the subsequent monitoring conducted over two decades. After the contamination assessment by the late 80s, a rehabilitation plan was carried out in the early 90s, in which the contaminated soil and water have been removed and reduced, respectively. No further attempt to neutralize the water or any remediation has been carried out. A toxicity monitoring plan based on toxicity assays with the fish Poecilia reticulata was employed to verify the natural rehabilitation of the pond. The data on toxicity, pH, conductivity, sulphate and dissolved iron recorded from 1994 to 2010 were also compiled and discussed. The collected data in 2003 and 2004 indicated changes in water quality and from them complementary management actions, namely improvement in the containment plant, were conducted in 2005. Results for toxicity assays and pH results indicated interannual changes in the water quality similar to rainy-dry periods. Moving average approach using pH data clearly showed the recovery process of Dunas Lake as well as the importance of the containment plan to reduce the contamination. Finally, a summary of the recent situation after two decades of rehabilitation is provided.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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).

  2. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. 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...

  5. Hydro-Biogeochemical Approaches to Understanding of Water Cycling in the Gwangneung Coniferous Catchment, South Korea

    NASA Astrophysics Data System (ADS)

    Kim, S.; Choi, H.; Lim, J.

    2012-12-01

    The spatial and temporal sources of headwater catchment runoff are important factors in our understanding of the dominant controls on catchment runoff. The information on flowpath, storage, residence time, and interactions of water and materials transport in a catchment is the prerequisite to the understanding and predicting of water cycling in the mountainous landscapes. In this presentation, along with some up-to-date results of hydro-biogeochemical researches, we present the principal methods that are currently used in Forest Water Resources Laboratory, Korea Forest Research Institute to obtain such information. Various catchment hydrological processes have been examined on the basis of the water table fluctuations, the end-member mixing model, the cross correlation analysis, and stable isotope. The stream discharge from the surface and shallow soil layer momentarily dominated at peak flow, and then its relative contribution decreased as precipitation intensity declined. Such a pattern (though with a greater magnitude) is consistent with those reported in many mixing-model studies of forested catchments. Overall surface discharge, on the other hand, steadily increased with subsequent storm events throughout the season. The previous study suggested that maintained precipitation expands saturation zone and increases macropore flow in the forested catchment. Such a macropore flow delivers new water in which dissolved ion concentrations are low because of short contact time with soil and bedrock. In the Gwangneung coniferous forest catchment, the contribution of surface discharge was relatively large, and the changes in the amount, intensity and patterns of precipitation affected both the flowpath and the mean residence time of water. Particularly during the summer monsoon, changes in precipitation patterns and hydrological processes in the catchment influenced the carbon cycle such that the persistent precipitation increased the discharge of dissolved organic

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

    PubMed

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

    2015-01-13

    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.

  7. 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

  8. 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

  9. 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

    2016-07-26

    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).

  10. Sub-tropical freshwater storage catchments: major greenhouse gas sinks?

    NASA Astrophysics Data System (ADS)

    Grinham, Alistair; Dunbabin, Matthew

    2013-04-01

    The relatively unstudied catchments and freshwater storages of the sub-tropics represent a potentially important gap in understanding global greenhouse gas cycling. The low number of studies may bias attempts to include this region's contribution to global greenhouse gas cycling, as very few studies have examined the major drivers behind terrestrial and aquatic greenhouse cycling in such sub-tropical areas. In addition, the uncertainty associated in quantifying greenhouse gas emission rates is relatively unknown. This information is crucial to determine whether freshwater storages and their associated catchments are net sources or sinks of greenhouse gas. Here, we present a greenhouse gas audit of the catchment and freshwater storage of Little Nerang Dam to determine the greenhouse gas status of the system as a whole. Little Nerang Dam is a sub-tropical freshwater storage located in Southeast Queensland, Australia. The catchment is in a relatively pristine condition with over 85% native forest remaining dominated by carbon dense Eucalypt species trees. Aquatic surface area is approximately 0.5 km2 in contrast to the terrestrial surface area of 35 km2. This system is an ideal model to investigate drivers behind greenhouse cycling in a relatively undisturbed catchment. A comprehensive field survey was conducted to estimate the major pools of carbon including terrestrial above and belowground fractions as well as the aquatic sediment and water column fractions. Greenhouse rates of emissions and sequestration were monitored over an annual cycle; parameters included tree growth rates, soil respiration, forest litter fall rates and aquatic methane and nitrous oxide fluxes. Results demonstrated the terrestrial carbon pool exceeded the aquatic pool by at least 2 orders of magnitude. When emission and sequestration rates were expressed as CO2 equivalents per unit area catchment sequestration was approximately double that of catchment and storage emissions. When rates were

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Temporal and Spatial Patterns of Preferential Flow Occurrence in the Shale Hills Catchment: From the Hillslope to the Catchment Scales

    NASA Astrophysics Data System (ADS)

    Liu, H.; Lin, H.

    2013-12-01

    Understanding temporal and spatial patterns of preferential flow (PF) occurrence is important in revealing hillslope and catchment hydrologic and biogeochemical processes. Quantitative assessment of the frequency and control of PF occurrence in the field, however, has been limited, especially at the landscape scale of hillslope and catchment. By using 5.5-years' (2007-2012) real-time soil moisture at 10 sites response to 323 precipitation events, we tested the temporal consistency of PF occurrence at the hillslope scale in the forested Shale Hills Catchment; and by using 25 additional sites with at least 1-year data (2011-2012), we evaluated the spatial patterns of PF occurrence across the catchment. To explore the potential effects of PF occurrence on catchment hydrology, wavelet analysis was performed on the recorded time series of hydrological signals (i.e., precipitation, soil moisture, catchment discharge). Considerable temporal consistence was observed in both the frequency and the main controls of PF occurrence at the hillslope scale, which was attributed largely to the statistical stability of precipitation pattern over the monitoring period and the relatively stable subsurface preferential pathways. Preferential flow tended to occur more often in response to intense rainfall events, and favored the conditions at dry hilltop or wet valley floor sites. When upscaling to the entire catchment, topographic control on the PF occurrence was amplified remarkably, leading to the identification of a subsurface PF network in the catchment. Higher frequency of PF occurrence was observed at the valley floor (average 48%), hilltop (average 46%), and swales/hillslopes near the stream (average 40%), while the hillslopes in the eastern part of the catchment were least likely to experience PF (0-20%). No clear relationship, however, was observed between terrain attributes and PF occurrence, because the initiation and persistency of PF in this catchment was controlled

  17. 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.

  18. 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

  19. Moments of catchment storm area

    NASA Technical Reports Server (NTRS)

    Eagleson, P. S.; Wang, Q.

    1985-01-01

    The portion of a catchment covered by a stationary rainstorm is modeled by the common area of two overlapping circles. Given that rain occurs within the catchment and conditioned by fixed storm and catchment sizes, the first two moments of the distribution of the common area are derived from purely geometrical considerations. The variance of the wetted fraction is shown to peak when the catchment size is equal to the size of the predominant storm. The conditioning on storm size is removed by assuming a probability distribution based upon the observed fractal behavior of cloud and rainstorm areas.

  20. 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.

  1. 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

  2. Is the subarctic landscape still a carbon sink? Evidence from a detailed catchment balance

    NASA Astrophysics Data System (ADS)

    Lundin, Erik J.; Klaminder, Jonatan; Giesler, Reiner; Persson, Andreas; Olefeldt, David; Heliasz, Michal; Christensen, Torben R.; Karlsson, Jan

    2016-03-01

    Climate warming raises the question whether high-latitude landscape still function as net carbon (C) sinks. By compiling an integrated C balance for an intensely studied subarctic catchment, we show that this catchment's C balance is not likely to be a strong current sink of C, a commonly held assumption. In fact, it is more plausible (71% probability) that the studied catchment functions as a C source (-11 ± 20 g C m-2 yr-1). Analyses of individual fluxes indicate that soil and aquatic C losses offset C sequestering in other landscape components (e.g., peatlands and aboveground forest biomass). Our results stress the importance of fully integrated catchment C balance estimates and highlight the importance of upland soils and their interaction with the aquatic network for the catchment C balance.

  3. Hydrological Catchment Similarity Assessment in Geum River Catchments, Korea

    NASA Astrophysics Data System (ADS)

    Ko, Ara; Park, Kisoon; Lee, Hyosang

    2013-04-01

    Similarity measure of catchments is essential for regionalization studies, which provide in depth analysis in hydrological response and flood estimations at ungauged catchments. However, this similarity measure is often biased to the selected catchments and is notclearly explained in hydrological sense. This study applied a type of hydrological similarity distance measure-Flood Estimation Handbook to 25 Geum river catchments, Korea. Three Catchment Characteristics, Area (A)-Annual precipitation (SAAR)-SCS Curve Number (CN), are used in Euclidian distance measures. Furthermore, six index of Flow Duration Curve (ILow:Q275/Q185, IDrought:Q355/Q185, IFlood:Qmax/Q185, IAbundant:Q95/Q185, IFloodDuration:Q10/Q355 and IRiverRegime:Qmax/Qmin) are applied to clustering analysis of SPSS. The catchments' grouping of hydrological similarity measures suggests three groups: H1 (Cheongseong, Gidae, Bukil, Oksan, Seockhwa, Habgang and Sangyeogyo), H2 (Cheongju, Guryong, Ugon, Boksu, Useong and Seokdong) and H3 (Muju, Yangganggyo and YongdamDam). The four catchments (Cheoncheon, Donghyang, DaecheongDam and Indong) are not grouped in this study. The clustering analysis of FDC provides four Groups; CFDC1 (Muju, YongdamDam, Yangganggyo, DaecheongDam, Cheongseong, Gidae, Seokhwa, Bukil, Habgang, Cheongju, Oksan, Yuseong and Guryong), CFDC2 (Cheoncheon, Donghyang, Boksu, Indong, Nonsan, Seokdong, Ugon, Simcheon, Useong and Sangyeogyo), CFDC3 (Songcheon) and CFDC4 (Tanbu). The six catchments (out of seven) of H1 are grouped in CFDC1, while Sangyeogyo is grouped in CFDC2. The four catchments (out of six) of H2 are also grouped in CFDC2, while Cheongju and Guryong are grouped in CFDC1. The catchments of H3 are categorized in CFDC1. The authors examine the results (H1, H2 and H3) of similarity measure based on catchment physical descriptors with results (CFDC1 and CFDC2) of clustering based on catchment hydrological response. The results of hydrological similarity measures are supported by

  4. Permafrost conditions in peatlands regulate magnitude, timing, and chemical composition of catchment dissolved organic carbon export.

    PubMed

    Olefeldt, David; Roulet, Nigel T

    2014-10-01

    Permafrost thaw in peatlands has the potential to alter catchment export of dissolved organic carbon (DOC) and thus influence downstream aquatic C cycling. Subarctic peatlands are often mosaics of different peatland types, where permafrost conditions regulate the hydrological setting of each type. We show that hydrological setting is key to observed differences in magnitude, timing, and chemical composition of DOC export between permafrost and nonpermafrost peatland types, and that these differences influence the export of DOC of larger catchments even when peatlands are minor catchment components. In many aspects, DOC export from a studied peatland permafrost plateau was similar to that of a forested upland catchment. Similarities included low annual export (2-3 g C m(-2) ) dominated by the snow melt period (~70%), and how substantial DOC export following storms required wet antecedent conditions. Conversely, nonpermafrost fens had higher DOC export (7 g C m(-2) ), resulting from sustained hydrological connectivity during summer. Chemical composition of catchment DOC export arose from the mixing of highly aromatic DOC from organic soils from permafrost plateau soil water and upland forest surface horizons with nonaromatic DOC from mineral soil groundwater, but was further modulated by fens. Increasing aromaticity from fen inflow to outlet was substantial and depended on both water residence time and water temperature. The role of fens as catchment biogeochemical hotspots was further emphasized by their capacity for sulfate retention. As a result of fen characteristics, a 4% fen cover in a mixed catchment was responsible for 34% higher DOC export, 50% higher DOC concentrations and ~10% higher DOC aromaticity at the catchment outlet during summer compared to a nonpeatland upland catchment. Expansion of fens due to thaw thus has potential to influence landscape C cycling by increasing fen capacity to act as biogeochemical hotspots, amplifying aquatic C cycling, and

  5. Nonparametric method for estimating the effects of climatic and catchment characteristics on mean annual evapotranspiration

    NASA Astrophysics Data System (ADS)

    Shao, Quanxi; Traylen, Anthony; Zhang, Lu

    2012-03-01

    It is now well known that forested catchments have higher evapotranspiration than grassed catchments. Models for mean annual evapotranspiration have been developed to quantify catchment scale differences in mean annual evapotranspiration. Zhang et al. (2001) developed a simple, one parameter, model for the relationships between evapotranspiration and vegetation cover by evaluating the differences of model parameter values for different vegetation covers. However, other factors such as climate and catchment topography may also affect evapotranspiration and therefore the model parameter. Simple models acknowledging only categorical vegetation cover (forested, mixed, and grassed) may introduce some uncertainty, and more seriously, lead to inconsistent conclusions regarding relationships between vegetation cover and evapotranspiration. Zhang et al. (2004) investigated possible inclusion of climatic factors and catchment characteristics to improve the estimation of mean annual evapotranspiration by modeling the residuals of the model parameter via a stepwise linear regression. In this paper we propose the use of a multivariate adaptive regression spline (MARS) model for estimating the model parameter. In contrast to a simple stepwise regression, the MARS model provides not only insight into the interactions between explanatory factors but also a potential for prediction for ungauged basins as long as the values of explanatory factors are within the domain of calibration catchments. The MARS model is able to determine statistically significant factors and therefore is a powerful tool to identify important factors and their interactions. Using 241 Australian catchments where climate factors and catchment characteristics are available, we found the following significant terms affecting the mean annual evapotranspiration. (1) The functional relationship with the number of months that peak precipitation follows peak potential evapotranspiration (PfE) states that closer phase

  6. 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

  7. 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

  8. 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

  9. 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.

  10. The effects of four acidifying sprays, vinegar, and water on canine cutaneous pH levels.

    PubMed

    Matousek, Jennifer L; Campbell, Karen L; Kakoma, Ibulaimu; Schaeffer, David J

    2003-01-01

    This study determined the extent and duration of cutaneous acidification caused by a single application of four acidifying sprays, vinegar, and water. Multivariate repeated measures analysis of variance revealed a significant difference between the six sprays (F = 15.3; P < or = 0.001). Linear contrast tests showed that the effects of the acidifying sprays were significantly different from vinegar and water (F = 6.0; P < or = 0.001), and vinegar was significantly different from water (F = 13.8; P < or = 0.001). The acidifying sprays decreased cutaneous pH to < 6.0 for a mean range of 50 to 65 hours, while vinegar did so for a mean of 12 hours.

  11. 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.

  12. Assessment of LULC and climate change on the hydrology of Ashti Catchment, India using VIC model

    NASA Astrophysics Data System (ADS)

    Hengade, Narendra; Eldho, T. I.

    2016-12-01

    The assessment of land use land cover (LULC) and climate change over the hydrology of a catchment has become inevitable and is an essential aspect to understand the water resources-related problems within the catchment. For large catchments, mesoscale models such as variable infiltration capacity (VIC) model are required for appropriate hydrological assessment. In this study, Ashti Catchment (sub-catchment of Godavari Basin in India) is considered as a case study to evaluate the impacts of LULC changes and rainfall trends on the hydrological variables using VIC model. The land cover data and rainfall trends for 40 years (1971-2010) were used as driving input parameters to simulate the hydrological changes over the Ashti Catchment and the results are compared with observed runoff. The good agreement between observed and simulated streamflows emphasises that the VIC model is able to evaluate the hydrological changes within the major catchment, satisfactorily. Further, the study shows that evapotranspiration is predominantly governed by the vegetation classes. Evapotranspiration is higher for the forest cover as compared to the evapotranspiration for shrubland/grassland, as the trees with deeper roots draws the soil moisture from the deeper soil layers. The results show that the spatial extent of change in rainfall trends is small as compared to the total catchment. The hydrological response of the catchment shows that small changes in monsoon rainfall predominantly contribute to runoff, which results in higher changes in runoff as the potential evapotranspiration within the catchments is achieved. The study also emphasises that the hydrological implications of climate change are not very significant on the Ashti Catchment, during the last 40 years (1971-2010).

  13. Short-term effects of clear-cutting on the water chemistry of two boreal streams in northern Sweden: a paired catchment study.

    PubMed

    Löfgren, Stefan; Ring, Eva; von Brömssen, Claudia; Sørensen, Rasmus; Högbom, Lars

    2009-11-01

    The effects of clear-cutting on stream-water chemistry in northern Sweden remain largely unexplored. Here we report data collected during a reference period and the first two years after logging in two typical partially harvested northern catchments; the objective was to compare water chemistry along the stream with and without a forest buffer. Two typical uncut reference catchments are included for comparison. Runoff was measured at the outlet of each catchment, and water samples were generally taken every second week and analyzed for 20 constituents. Logging resulted in increased runoff and increased concentrations of sodium, potassium, chloride, total nitrogen, total phosphorus, and suspended material from both catchments. Nitrate (NO3-) leaching increased only from the catchment without a forest buffer. It has not yet been possible to evaluate fully the effects of the forest buffer on the NO3- leaching because the uphill clear-cut area leached minimal amounts of NO3-.

  14. 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

  15. 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.

  16. 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.

  17. Carbon stock estimation in the catchment of Kotli Bhel 1A hydroelectric reservoir, Uttarakhand, India.

    PubMed

    Kumar, Amit; Sharma, M P

    2016-12-01

    Constructions of dams/reservoirs all over the world are reported to emit significant amount of greenhouse gases (GHGs) and are considered as environmental polluters. Organic carbon is contributed by the forest in the catchment, part of soil organic carbon is transported through the runoffs to the reservoir and undergoes aerobic and anaerobic degradation with time to release GHGs to the atmosphere. Literature reveals that no work is available on the estimation of 'C' stock of trees of forest catchment for assessing/predicting the GHGs emissions from the reservoirs to atmosphere. To assess the GHGs emission potential of the reservoir, an attempt is made in the study to estimate the 'C' stock in the forest catchment of Kotli Bhel 1A hydroelectric reservoir located in Tehri Garhwal district of Uttarakhand, India. For this purpose, the selected area was categorized into the site-I, II and III along the Bhagirathi River based on type of forest available in the catchment. The total carbon density (TCD) of tree species of different forest types was calculated using diameter at breast height (dbh) and trees height. The results found that the TCD of forest catchment was found 76.96MgCha(-1) as the highest at the site-II and 29.93MgCha(-1) as lowest at site-I with mean of 51.50MgCha(-1). The estimated forest 'C' stock shall be used to know the amount of carbon present before and after construction of the dam and to predict net GHGs emissions. The results may be helpful to study the potential of a given reservoir to release GHG and its subsequent impacts on global warming/climate challenges.

  18. Linking catchment structure to hydrologic function: Implications of catchment topography for patterns of landscape hydrologic connectivity and stream flow dynamics

    NASA Astrophysics Data System (ADS)

    Jencso, K. G.; McGlynn, B. L.; Marshall, L. A.

    2010-12-01

    The relationship between catchment structure (topography and topology), stream network hydrologic connectivity, and runoff response remains poorly understood. Hillslope-riparian-stream (HRS) water table connectivity serves as the hydrologic linkage between a catchment’s uplands and the channel network and facilitates the transmission of water and solutes to streams. While there has been tremendous interest in the concept of hydrological connectivity to characterize catchments, there are relatively few studies that have quantified hydrologic connectivity at the stream network and catchment scales. Here, we examine how catchment topography influenced patterns of stream network HRS connectivity and resultant runoff dynamics across 11 nested headwater catchments in the Tenderfoot Creek Experimental Forest (TCEF), MT. This study extends the empirical findings of Jencso et al. (2009) who found a strong linear relationship (r2 = 0.92) between the upslope accumulated area (UAA) and annual duration of shallow ground water table connectivity observed across 24 HRS transects (146 groundwater recording wells) within the TCEF. We applied this relationship to the entire stream network to quantify the frequency distribution of stream network connectivity through time (as a function of UAA) and ascertain its relationship to catchment-scale runoff dynamics. Each catchment’s estimated connectivity duration curve (CDC) was highly related to its flow duration curve (FDC); albeit the rate of change of runoff with respect to stream network connectedness varied significantly across catchments. To ascertain potential reasons for these differences we compared the slope of each catchment’s CDC-FDC relationship (annual, peak, transition and baseflow periods) in multiple linear models against median values of common terrain indices and land cover-vegetation characteristics. Significant predictors (p<0.05) included the flow path distance to the creek (DFC), the flow path gradient to the

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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…

  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 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)).

  6. 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.

  7. 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

  8. Towards Estimating the Nutrient Balance of the Hydrologic Open Air Laboratory (HOAL) Catchment, Lower Austria

    NASA Astrophysics Data System (ADS)

    Exner-Kittridge, Michael; Zessner, Matthias; Broer, Martine; Eder, Alexander; Strauss, Peter; Blöschl, Günter

    2010-05-01

    The fate of nutrients introduced by human activities have significant impacts on both nature and our civilization. Excessive nutrients can contaminate our drinking water as well as promote algae blooms that deplete the surrounding waters of oxygen for aquatic life. It is estimated that agriculture in Austria contributes approximately 60% to the total discharge of nitrogen and 40% to the total discharge of phosphorus. Understanding the specific pathways and sources of nitrogen and phosphorus from agriculture land could greatly improve our ability to mitigate for excessive discharges if the problems can be targeted more precisely. The objective of our research is to determine the complete nitrogen and phosphorous balance within a 66.7 hectare catchment in Lower Austria. The Hydrologic Open Air Laboratory (HOAL) catchment is located in Lower Austria approximately 100 km west of Vienna. The HOAL catchment was established in 2009 through funding by the Austrian Science Foundation to be used for multidisciplinary hydrologic research for understanding water flow and transport processes in catchments. The catchment land cover is characterized as 90% agriculture, 5% impermeable surface, and 3% forest. The predominant soil type is a clayey silt loam and a section of the catchment contain a subsurface tile drainage network that extend approximately 5.5 km. Nitrogen and phosphorus are the two primary nutrients assessed in this study. To accomplish the nutrient balance, the research is divided into three different scales: Field Scale, Subcatchment Scale, and Catchment Scale. The Catchment scale encompasses the entirety of the catchment, the subcatchment scale encompasses a 6.4 hectare area within the catchment that is completely underlain by the tile drainage network, and the field scale studies are performed on several square meter plots within the subcatchment. Each scale attempts to determine different parts of the total nutrient budget. The initial phase of the research

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Linking sediment fingerprinting and modeling outputs for a Spanish Pyrenean river catchment.

    NASA Astrophysics Data System (ADS)

    Palazón, Leticia; Latorre, Borja; Gaspar, Leticia; Blake, Williams H.; Smith, Hugh G.; Navas, Ana

    2015-04-01

    Indirect techniques to study fine sediment redistribution in river catchments could provide unique and diverse information, which, when combined become a powerful tool to address catchment management problems. Such combinations could solve limitations of individual techniques and provide different lines of information to address a particular problem. The Barasona reservoir has suffered from siltation since its construction, with the loss of over one third of its storage volume in around 30 study years (period 1972-1996). Information on sediment production from tributary catchments for the reservoir is required to develop management plans for maintaining reservoir sustainability. Large spatial variability in sediment delivery was found in previous studies in the Barasona catchment and the major sediment sources identified included badlands developed in the middle part of the catchment and the agricultural fields in its lower part. From the diverse range of indirect techniques, fingerprinting sediment sources and computer models could be linked to obtain a more holistic view of the processes related to sediment redistribution in the Barasona river catchment (1509 km2, Central Spanish Pyrenees), which comprises agricultural and forest land uses. In the present study, the results from a fingerprinting procedure and the SWAT model were compared and combined to improve the knowledge of land use sediment source contributions to the reservoir. Samples from the study catchment were used to define soil parameters for the model and for fingerprinting the land use sources. The fingerprinting approach provided information about relative contributions from land use sources to the superficial sediment samples taken from the reservoir infill. The calibration and validation of the model provided valuable information, for example on the timescale of sediment production from the different land uses within the catchment. Linking results from both techniques enabled us to achieve a

  16. Catchment sensitivity to changing climate conditions: the importance of landscape characteristic

    NASA Astrophysics Data System (ADS)

    Teutschbein, C.; Karlsen, R.; Grabs, T.; Laudon, H.; Bishop, K. H.

    2014-12-01

    The scientific literature is full of studies analyzing future climate change impacts on hydrology with focus on individual catchments. However, we recently found 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 neighboring catchments in Northern Sweden with slightly different topography, land cover, size and geology. Current (1981-2010) and future (2061-2090) streamflow was simulated with the HBV light model. Climate projections were based on 14 regional climate models (ENSEMBLES EU project) and bias-corrected with a distribution-mapping approach. Our simulations revealed that future spring flood peaks will occur much earlier and decrease by 13 to 32 %, whereas winter base flows will increase slightly. 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, these values also highlight that there is a large variability amongst the catchments in their hydrological response to the same future climate conditions. For example, spring flood peaks in catchments without wetlands decrease by only 13 to 15 %, whereas catchments with wetlands show a spring flood peak reduction of 20 to 32 %. In addition to wetlands, we also identified lakes, peat soils and higher elevations as factors that seem to cause a stronger hydrological response to the climate change signal, whereas catchments dominated by forests, steeper slopes and till soils seem to be less strongly affected by a changing climate. Therefore, our results suggest that the sensitivity of catchments to future climate conditions is strongly linked to

  17. 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.

  18. Relative acidifying activity of anionic salts commonly used to prevent milk fever.

    PubMed

    Goff, J P; Ruiz, R; Horst, R L

    2004-05-01

    High cation diets can cause milk fever in dairy cows as they induce a metabolic alkalosis reducing the ability of the cow to maintain calcium homeostasis at the onset of lactation. Adding anions to the diet can offset the effect of the high cation forages by inducing a mild metabolic acidosis, restoring the ability to maintain calcium homeostasis. The difference in mEq of dietary cations and anions (DCAD) is most often expressed as (Na(+) + K+) - (Cl- + S(--)). This equation implies that a mEq of chloride and a mEq of sulfate are equipotent in their ability to alter acid-base balance of the cow. Using blood and urine pH to monitor effects on acid-base balance, experiments were conducted to test the relative acidifying activity of various sulfate and chloride anion sources in nonpregnant, nonlactating Jersey cows. Across all experiments, chloride proved to have about 1.6 times the acidifying activity of sulfate. Calcium and magnesium, ignored by the common DCAD equation, had a small but significant alkalinizing effect when accompanying chloride or sulfate. The ranking of the anion sources tested at a dose of 2 Eq/d, from most to least potent urine acidifier, was hydrochloric acid, ammonium chloride, calcium chloride, calcium sulfate, magnesium sulfate, and sulfur. These data should allow more accurate prediction of the response of late gestation cows to dietary cation-anion manipulation.

  19. 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

  20. 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 and

  1. Quantifying the hydrological impact of simulated changes in land use on peak discharge in a small catchment.

    PubMed

    Kalantari, Zahra; Lyon, Steve W; Folkeson, Lennart; French, Helen K; Stolte, Jannes; Jansson, Per-Erik; Sassner, Mona

    2014-01-01

    A physically-based, distributed hydrological model (MIKE SHE) was used to quantify overland runoff in response to four extreme rain events and four types of simulated land use measure in a catchment in Norway. The current land use in the catchment comprises arable lands, forest, urban areas and a stream that passes under a motorway at the catchment outlet. This model simulation study demonstrates how the composition and configuration of land use measures affect discharge at the catchment outlet differently in response to storms of different sizes. For example, clear-cutting on 30% of the catchment area produced a 60% increase in peak discharge and a 10% increase in total runoff resulting from a 50-year storm event in summer, but the effects on peak discharge were less pronounced during smaller storms. Reforestation of 60% of the catchment area was the most effective measure in reducing peak flows for smaller (2-, 5- and 10-year) storms. Introducing grassed waterways reduced water velocity in the stream and resulted in a 28% reduction in peak flow at the catchment outlet for the 50-year storm event. Overall, the results indicate that the specific effect of land use measures on catchment discharge depends on their spatial distribution and on the size and timing of storm events.

  2. 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.

  3. Characterization of hydrologic inputs and streamflow pathways in headwater catchments of Boulder Creek Watershed, Colorado

    NASA Astrophysics Data System (ADS)

    Cowie, R. M.; Williams, M. W.; Mills, T. J.

    2012-12-01

    Streamflow pathways were investigated using isotopic and geochemical tracers in two gauged headwater catchments located at different elevations within the forested area of Boulder Creek Watershed, Colorado. Using diagnostic tools of mixing models indicates that both catchments fit reasonable well to a 1-D (two endmember) model for streamflow generation. End member mixing analysis (EMMA) suggests that streamflow at the lower elevation Gordon Gulch catchment (mean elevation 2627 m) was a combination of shallow subsurface flow and groundwater with limited influence from direct runoff. Steamflow at the higher elevation Como Creek catchment (mean elevation 3230 m) was a combination of runoff from snowmelt and groundwater. During the study period the total annual precipitation and the amount of precipitation falling as snow increased with elevation from 456 mm (41% snow) at Gordon Gulch to 804 mm (71% snow) at Como Creek. The resulting increase in winter snow accumulation at Como Creek demonstrates differences in timing and magnitude of hydrologic inputs between the two catchments and provides a potential driver for the differences in streamflow pathways. These results highlight the importance of understanding variations in streamflow pathways in relation to climatic variations across headwater mountain catchments. The broader impacts of streamflow pathway variations on steam nutrients will also be addressed.

  4. Landscape controls on spatiotemporal discharge variability in a boreal catchment

    NASA Astrophysics Data System (ADS)

    Karlsen, R. H.; Grabs, T.; Bishop, K.; Buffam, I.; Laudon, H.; Seibert, J.

    2016-08-01

    Improving the understanding of how stream flow dynamics are influenced by landscape characteristics, such as soils, vegetation and terrain, is a central endeavor of catchment hydrology. Here we investigate how spatial variability in stream flow is related to landscape characteristics using specific discharge time series from 14 partly nested subcatchments in the Krycklan basin (0.12 - 68 km2). Multivariate principal component analyses combined with univariate analyses showed that while variability in landscape characteristics and specific discharge were strongly related, the spatial patterns varied with season and wetness conditions. During spring snowmelt and at the annual scale, specific discharge was positively related to the sum of wetland and lake area. During summer, when flows are lowest, specific discharge was negatively related to catchment tree volume, but positively related to deeper sediment deposits and catchment area. The results indicate how more densely forested areas on till soils become relatively drier during summer months, while wet areas and deeper sediment soils maintain a higher summer base flow. Annual and seasonal differences in specific discharge can therefore be explained to a large extent by expected variability in evapotranspiration fluxes and snow accumulation. These analyses provide an organizing principle for how specific discharge varies spatially across the boreal landscape, and how this variation is manifested for different wetness conditions, seasons and time scales.

  5. Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China.

    PubMed

    Shen, Jianlin; Liu, Jieyun; Li, Yong; Li, Yuyuan; Wang, Yi; Liu, Xuejun; Wu, Jinshui

    2014-09-01

    Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. The impact of pasture conversion on nutrient cycles of tropical streams on the Osa Peninsula, Costa Rica: a paired catchment approach

    NASA Astrophysics Data System (ADS)

    Bringhurst, K.; Jordan, P.

    2011-12-01

    Changes in nutrient and hydrologic cycles caused by land disturbance typically lead to detrimental changes to ecosystems. This study utilized a paired, small-catchment approach to examine the effect of deforestation on nutrient transfer and hydrological discharge and the resulting impact on soils and streams of the Osa Peninsula, Costa Rica. Two first order streams were chosen, the first catchment had been cleared for pasture and the second consisted of undisturbed tropical wet forest. Soil concentrations of organic matter, total and soil available P were higher in the forested catchment with decreases of >33% of each in the deforested catchment. The effect of deforestation on stream discharge was a 59% increase in flow during the wet season and an increase in the Q5:Q95 ratio showing that the deforested stream was flashier. The deforested catchment loss of dissolved inorganic nitrogen (DIN) increased 95% over the forested catchment. Soluble reactive phosphorus (SRP) showed an increase in load of 43% in the deforested catchment compared to the forested catchment. The molar N:P ratios were lower than the Redfield ratio and both streams were well below the level at which N-limitation of lotic algal growth has been reported, therefore it is hypothesized that N is the limiting nutrient in streams in the study area. Soil nutrient depletion in the deforested catchment, accelerated by a changed hydrologic regime, is the likely trajectory of soil-water interactions in this tropical ecosystem. This will likely be among the secondary impacts should deforestation become widespread along this stretch of the Pacific coastline, with associated eutrophication of receiving transitional and coastal waters.

  11. Fresh and preserved green fodder modify effects of urinary acidifiers on urine pH of horses.

    PubMed

    Goren, G; Fritz, J; Dillitzer, N; Hipp, B; Kienzle, E

    2014-04-01

    Hay stabilises urine pH in horses. It is unknown whether this is an effect of structure or of chemical composition. In this study, four ponies (230-384 kg body weight [BW]) were fed six different diets with either a structure or a composition similar to hay with and without acidifiers in a cross-over experimental design in amounts to maintain body weight with the following main compounds: Fresh grass (GRASS), alfalfa hay (ALF), grass cobs (COBS), grass silage (SIL), straw (STR) or extruded straw (STRe) for 2 to 10 days. Urine pH was measured in all trials, blood pH, blood base excess and bicarbonate as well as mineral balance were determined in GRASS, ALF, STR and STRe. In the trials with straw and extruded straw, urine pH decreased significantly (STR control: 7.8 ± 0.23, acidifier: 5.2 ± 0.38) when acidifiers were added, whereas in all other diets that were based on fresh or preserved green fodder, pH did not decrease below 7. Blood pH was similarly affected by diet and acidifiers. Acidifiers had little effect on the pre-prandial blood pH, only in diet STR there was a significant reduction in relation to control. Post-prandial blood pH was significantly reduced by acidifiers in all diets. Blood bicarbonate and base excess showed corresponding effects. Faecal and renal mineral excretion and apparent mineral digestibility were not systematically affected by diet or acidifiers except for chloride. Chloride added as inorganic chloride salt had an even better apparent digestibility than chloride originating from feed. Because only green plant material stabilised acid base balance, chlorophyll and its metabolites are discussed as potential mediators of the effect of green fodder on acid base balance.

  12. 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.

  13. Overland flow generation in two lithologically distinct rainforest catchments

    NASA Astrophysics Data System (ADS)

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

    2004-08-01

    Streams on uniformly rainforest-covered, but lithologically very diverse Barro Colorado Island in central Panamá 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 Ks 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.

  14. 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.

  15. 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.

  16. 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.

  17. Evaluation of sodium bisulphate and phosphoric acid as urine acidifiers for cats.

    PubMed

    Spears, Julie K; Grieshop, Christine M; Fahey, G C

    2003-10-01

    Eighteen cats were used to compare the urine acidifying properties of sodium bisulphate to phosphoric acid. Acidifying agents were added at one of three concentrations (0.4, 0.6, or 0.8%, as-is basis). Cats were offered a commercial diet to determine basal urinary pH, and then again for a 1 week period between blocks 1 and 2. Cats were acclimated to the diets for 6 days, and urine samples were collected on day 7 at 0, 4, and 8 h postfeeding to obtain pre- and postprandial urinary pH. Intakes of diets containing sodium bisulphate tended (P < 0.07) to be lower than intakes of diets containing phosphoric acid. Cats consuming the 0.8% phosphoric acid diet had higher (P < 0.05) food intakes than cats consuming either the 0.4 or 0.6% phosphoric acid-containing diets. There was significant (P = 0.01) linear and quadratic response for food intake in cats consuming the sodium bisulphate-containing diet. Cats consuming the 0.4 and 0.8% phosphoric acid-containing diets tended (P = 0.07) to have higher water intakes than cats consuming the 0.6% phosphoric acid-containing diet. There were no differences (P > 0.05) in urine pH and specific gravity between cats fed the different acidifier types. Cats consuming the 0.6% phosphoric acid-containing diet tended (P = 0.07) to have a higher urine pH 8 h post-feeding than cats consuming the 0.4 and 0.8% phosphoric acid-containing diets. Urine pH was highest at 4 h post-feeding except for cats fed the 0.4% sodium bisulphate- and the 0.6% phosphoric acid-containing diets. No differences (P > 0.05) between acidifiers were found in faecal score or in faecal dry matter and organic matter concentrations. A quadratic response was detected in faecal score for cats consuming the phosphoric acid-containing diets. Cats consuming the 0.6% phosphoric acid diet tended (P = 0.06) to have a lower faecal score than cats consuming the 0.4 and 0.8% phosphoric acid diets. For faecal dry matter, a linear trend was detected in cats consuming the sodium

  18. 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.

  19. 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

  20. 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.

  1. Annual rainfall based analysis of streamflow regime dynamics following vegetation cover changes in temperate and little rain catchments in Japan

    NASA Astrophysics Data System (ADS)

    Hosoda, I.

    2013-12-01

    Relationship between forest and runoff has been widely studied by paired catchment method. However, paired catchment method is not proper for long-term analysis because it is difficult to keep up the reference catchment in a constant condition for years. Therefore this study tried to find relationship between forest and runoff through relationship between annual rainfall and runoff. The study sites are the Kita-tani (17.3 ha, 36-246 m) and the Minami-tani (22.6 ha, 50-257 m) in the Tatsunokuchi-yama experimental watershed (34°42'N, 133°58'E) where measurement started in 1937. Since streamflow regime is highly influenced by change in catchment water storage, three-year weighted mean annual rainfall was applied. Runoff values for each year were segmental sums of streamflow regime curve (annual, 1st-95th, 96th-185th, 186th-275th, 276th-355th, and after 355th). In the relationships between the weighted annual rainfall and the runoff values for each segment in the whole period, the data in the period of 1998-2003 while the vegetation was most stable in the past 75 years in the both catchments were linearly distributed in the base part of scatter plot (r=0.61-0.96). These regression lines were used as criteria. Difference between observed runoff and estimated runoff by the regression equation (dQ) was calculated, and examined time series. The regression period was about 20 years past after severe pine disease around 1980, and the catchments were covered with Quercus serrata dominant mixed forest. In the both catchments, annual dQ in the period of 1937-2012 ranged from -10% to 30% of annual rainfall, and over 90% of annual dQ were consisted of 1-95th dQ. dQ variations for each segment tend to increase following pine disease and forest fire, and tend to approach toward zero following forest recovery. In recent years, dQ of the segments after 95th decreased less than zero in contrast to annual dQ increased. Similar tendency appeared in the early years in the Minami

  2. Land use transformation and the estimation of sediment budgets in small tropical catchments, Singapore

    NASA Astrophysics Data System (ADS)

    Higgitt, David

    2010-05-01

    A field-based monitoring programme has been conducted in forested and urbanized catchments in Singapore to elucidate the nature of sediment budgets and to define sediment and carbon flux. There have been relatively few studies of sediment budgets in tropical environments and these have mostly focused on disturbed systems. Here results from investigations of a headwater catchment in a remnant primary forest and in a freshwater swamp forest environment provide a context for examining the impact of land use change. Two centuries ago, the island Singapore was dominated by lowland Diterocarp forest, extensive estuarine mangroves and lowland freshwater swamp forest. Within 30 years of European arrival, less than 10% of the forest cover remained, although subsequently many areas which were cleared for plantations were reafforested to protect water supply reservoirs. Large scale engineering works in the urban drainage system have largely obliterated fluvial sedimentary archives, posing challenges for the reconstruction of longer term sediment budgets. Current concerns about the vulnerability of biodiversity to hydrological and water quality related impacts, coupled with the demands of water resource management and a turn towards river restoration, dictate the need for better understanding of sediment and nutrient fluxes. Very low sediment yields of less than 10 t km-2 yr-1 in the primary forest, comparable with other regional studies from undisturbed forest, can in part explain the poorly defined channel morphology of forest steams. However, both forest and urban streams exhibit flashy responses to rainfall events and a large proportion of the annual sediment load can be transported in a single event. Preliminary estimates of sediment and carbon fluxes for Singapore streams will be presented and approaches to the difficult task of reconstructing the impact of past land use change on sediment budgets discussed.

  3. 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

  4. 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…

  5. 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.

  6. 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.

  7. 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.

  8. Esterification of acidified oil with methanol by SPES/PES catalytic membrane.

    PubMed

    Shi, Wenying; He, Benqiao; Li, Jianxin

    2011-05-01

    A sulfonated polyethersulfone (SPES)/polyethersulfone (PES) blend catalytic membrane was prepared and used as a heterogeneous catalyst in the esterification of the acidified oil (acid value 153 mg KOH/g) with methanol for producing biodiesel. The results showed that the free fatty acids conversion reached 97.6% using SPES/PES catalytic membrane under the optimal esterification conditions. Meanwhile, the SPES/PES membrane with 20.3% degree of sulfonation showed a good catalytic stability. A pseudo-homogeneous kinetic model was established. The results indicated that the reaction rate constant increased with increasing methanol/acidified oil molar ratio, the loading of catalytic membrane and reaction temperature. The reaction order was 2 and the activation energy decreased from 74.65 to 21.07 kJ/mol with increasing catalytic membrane loading from 0 to 0.135 meq/g(oil). It implies that the esterification is not diffusively controlled but kinetically controlled. The predicted results were in good agreement with the experimental data.

  9. 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.

  10. [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.

  11. 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.

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

    PubMed Central

    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. PMID:25909190

  13. 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.

  14. 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.

  15. Mean water residence times in the pre-alpine Rietholzbach catchment

    NASA Astrophysics Data System (ADS)

    Lehner, I.; Bernasconi, S.; Seneviratne, S. I.

    2009-04-01

    The Rietholzbach catchment is a small, hilly pre-alpine basin in the north-eastern part of Switzerland. Its area is 3.31 km2 and it covers an altitude range between 682 and 950 m. The area is only sparsely populated and primarily used as pasture land (67 %), on steep slopes the land use is forest (25 %). A hydrological peculiarity is the congruence of surface and sub-surface catchment area. In 1975 measurements were initiated to determine and understand the water balance and its processes. Isotope measurements of all components of the water cycle started in 1994. The water samples of precipitation, soil water (discharge of a lysimeter), ground water, and river water are taken approximately bi-weekly. All samples are prepared by the CO2 gas equilibration technique and are analysed in terms of the oxygen isotopes by mass spectrometry. The samples are taken either at the gauge at the outflow of the catchment or next to the main measurement site in the upper third of the catchment where an other gauge, three groundwater wells, the lysimeter and the meteorological sensors are installed in close vicinity. Based on these data series this contribution will present estimates of the mean water residence times in the different components of the catchment.

  16. Catchment classification by means of hydrological models

    NASA Astrophysics Data System (ADS)

    Hellebrand, Hugo; Ley, Rita; Casper, Markus

    2013-04-01

    An important hydrological objective is catchment classification that will serve as a basis for the regionalisation of discharge parameters or model parameters. The main task of this study is the development and assessment of two classification approaches with respect to their efficiency in catchment classification. The study area in western Germany comprises about 80 catchments that range in size from 8 km2 up to 1500 km2, covering a wide range of geological substrata, soils, landscapes and mean annual precipitation. In a first approach Self Organising Maps (SOMs) use discharge characteristics or catchment characteristics to classify the catchments of the study area. Next, a reference hydrological model calibrates the catchments of the study area and tests the possibilities of parameter transfer. Compared to the transfer of parameters outside a class, for most catchments the model performance improves when parameters within a class are transferred. Thus, it should be possible to distinguish catchment classes by means of a hydrological model. The classification results of the SOM are compared to the classification results of the reference hydrological model in order to determine the latter validity. The second approach builds on the first approach in such a way that it uses the Superflex Modelling Framework instead of only one reference model. Within this framework multiple conceptual model structures can be calibrated and adapted. Input data for each calibration of a catchment are hourly time series of runoff, precipitation and evaporation for at least eight years. The calibration of multiple models for each catchment and their comparison allows for the assessment of the influence of different model structures on model performance. Learning loops analyse model performance and adapt model structures accordingly with a view to performance improvement. The result of the modelling exercise is a best performing model structure for each catchment that serves as a basis

  17. 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

  18. Stream water hydrochemistry as an indicator of carbon flow paths in Finnish peatland catchments during a spring snowmelt event.

    PubMed

    Dinsmore, Kerry J; Billett, Michael F; Dyson, Kirstie E; Harvey, Frank; Thomson, Amanda M; Piirainen, Sirpa; Kortelainen, Pirkko

    2011-10-15

    Extreme hydrological events are known to contribute significantly to total annual carbon export, the largest of which in Arctic and boreal catchments is spring snowmelt. Whilst previous work has quantified the export of carbon during snowmelt, the source of the carbon remains unclear. Here we use cation hydrochemistry to trace the primary flowpaths which govern the export of carbon during the snowmelt period; specifically we aim to examine the importance of snowpack meltwater to catchment carbon export. The study was carried out in two forested peatland (drained and undrained) catchments in Eastern Finland. Both catchments were characterised by base-poor stream water chemistry, with cation concentrations generally decreasing in response to increasing discharge. Streamflow during the snowmelt period was best described as a mixture of three sources: pre-event water, snowpack meltwater and a third dilute component we attribute to the upper snow layer which was chemically similar to recent precipitation. Over the study period, pre-event water contributed 32% and 43% of the total stream runoff in Välipuro (undrained) and Suopuro (drained), respectively. The results also suggest a greater near-surface throughflow component in Suopuro, the drained catchment, prior to snowmelt. CO(2) and DOC concentrations correlated positively with cation concentrations in both catchments indicating a common, peat/groundwater flowpath. CH(4) concentrations were significantly higher in the drained catchment and appeared to be transported in near-surface throughflow. Meltwater from the snowpack represented an important source of stream water CO(2) in both catchments, contributing up to 49% of total downstream CO(2) export during the study period. We conclude that the snowpack represents a potentially important, and often overlooked, transient carbon store in boreal snow-covered catchments.

  19. What can we learn from the hydrological modeling of small-scale catchments for the discharge and water balance modeling of mesoscale catchments?

    NASA Astrophysics Data System (ADS)

    Cornelissen, Thomas; Diekkrüger, Bernd; Bogena, Heye

    2015-04-01

    The application of 3D hydrological models remains a challenge both in research and application studies because the parameterization not only depends on the amount and quality of data available for calibration and validation but also on the spatial and temporal model resolution. In recent years, the model parameterization has improved with the availability of high resolution data (e.g. eddy-covariance, wireless soil sensor networks). Unfortunately, these high resolution data are typically only available for small scale research test sites. This study aims to upscale the parameterization from a highly equipped, small-scale catchment to a mesoscale catchment in order to reduce the parameterization uncertainty at that scale. The two nested catchments chosen for the study are the 0.38 km² large spruce covered Wüstebach catchment and the 42 km² large Erkensruhr catchment characterized by a mixture of spruce and beech forest and grassland vegetation. The 3D hydrogeological model HydroGeoSphere (HGS) has already been setup for the Wüstebach catchment in a previous study with a focus on the simulation performance of soil water dynamics and patterns. Thus, the parameterization process did not only optimize the water balance components but the catchment's wireless soil sensor network data were utilized to calibrate porosities in order to improve the simulation of soil moisture dynamics. In this study we compared different HGS model realizations for the Erkensruhr catchment with different input data. For the first model realization, the catchment is treated heterogeneous in terms of soil properties and topography but homogeneous with respect to land use, precipitation and potential evapotranspiration. For this case, the spruce forest parameterization and the climate input data were taken directly from the small-scale Wüstebach model realization. Next, the calibrated soil porosity for the Wüstebach catchment is applied to the Erkensruhr. Further model realizations

  20. 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.

  1. Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia.

    PubMed

    Cheyne, Susan M; Thompson, Claire J H; Phillips, Abigail C; Hill, Robyn M C; Limin, Suwido H

    2008-01-01

    We demonstrate that although auditory sampling is a useful tool, this method alone will not provide a truly accurate indication of population size, density and distribution of gibbons in an area. If auditory sampling alone is employed, we show that data collection must take place over a sufficient period to account for variation in calling patterns across seasons. The population of Hylobates albibarbis in the Sabangau catchment, Central Kalimantan, Indonesia, was surveyed from July to December 2005 using methods established previously. In addition, auditory sampling was complemented by detailed behavioural data on six habituated groups within the study area. Here we compare results from this study to those of a 1-month study conducted in 2004. The total population of the Sabangau catchment is estimated to be about in the tens of thousands, though numbers, distribution and density for the different forest subtypes vary considerably. We propose that future density surveys of gibbons must include data from all forest subtypes where gibbons are found and that extrapolating from one forest subtype is likely to yield inaccurate density and population estimates. We also propose that auditory census be carried out by using at least three listening posts (LP) in order to increase the area sampled and the chances of hearing groups. Our results suggest that the Sabangau catchment contains one of the largest remaining contiguous populations of Bornean agile gibbon.

  2. Type C bovine botulism outbreak due to carcass contaminated non-acidified silage.

    PubMed

    Myllykoski, J; Lindström, M; Keto-Timonen, R; Söderholm, H; Jakala, J; Kallio, H; Sukura, A; Korkeala, H

    2009-02-01

    The first reported bovine botulism outbreak in Finland is described. Nine out of 90 cattle on a dairy farm died after being fed non-acidified silage contaminated by animal carcasses. Type C botulinum neurotoxin gene was detected in one heifer by polymerase chain reaction (PCR) and the neurotoxin was detected by the mouse bioassay. Clostridium botulinum type C was isolated from liver samples. The isolated strain was identified with amplified fragment length polymorphism (AFLP) analysis as group III C. botulinum. To our knowledge, this is the first time that a type C bovine botulism outbreak has been diagnosed by PCR and confirmed by subsequent isolation and AFLP identification of the disease strain. The importance of the acidification process in silage production to inhibit C. botulinum toxin production in silage and thus to prevent further botulism outbreaks is emphasized. Nevertheless, preformed toxin in the carcass is not destroyed by acid.

  3. Rapid restoration of methanogenesis in an acidified UASB reactor treating 2,4,6-trichlorophenol (TCP).

    PubMed

    Díaz-Báez, María Consuelo; Valderrama-Rincon, Juan Daniel

    2017-02-15

    Anaerobic bioreactors are often used for removal of xenobiotic and highly toxic pollutants from wastewater. Most of the time, the pollutant is so toxic that the stability of the reactor becomes compromised. It is well known that methanogens are one of the most sensitive organisms in the anaerobic consortia and hence the stability of the reactors is highly dependant on methanogenesis. Unfortunately few studies have focused on recovering the methanogenic activity once it has been inhibited by highly toxic pollutants. Here we establish a quick recovery strategy for neutralization of an acidified UASB reactor after failure by intoxication with an excess of TCP in the influent. Once the reactor returned to pH values compatible with methanogenesis, biogas production was re-started after one day and the system was re-acclimated to TCP. Successful removal of TCP from synthetic wastewater was shown for concentrations up to 70mg/L after restoration.

  4. Purification of empty fruit bunch (EFB) and kenaf soda lignin with acidified water

    NASA Astrophysics Data System (ADS)

    Hashim, Sharifah Nurul Ain Syed; Zakaria, Sarani; Jaafar, Sharifah Nabihah Syed; Hua, Chia Chin

    2014-09-01

    In this current study, the soda lignins from empty fruit bunch (EFB) and kenaf core were recovered by two step precipitation method. The objective of this research is to study the purity of lignin by washing the lignins with acidified water. The purified lignins were undergone characterization by FT-IR, Uv-Vis and XRD. The FT-IR analysis shows that kenaf core has Guaiacyl(G) and Syringyl(S) unit meanwhile EFB has Hydroxyphenyl(H), Guaiacyl(G) and Syringyl(S) unit of lignin. As for XRD analysis, the non-purified shows that the existence of impurities which is salt (NaCl). The UV analysis shows the higher absorbance which lead to the purity of lignin.

  5. 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.

  6. 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.

  7. 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.

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

    PubMed Central

    Abu Elala, Nermeen M.; Ragaa, Naela M.

    2014-01-01

    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

  9. 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.

  10. Impact of tree species on nutrient stocks in the forest floors of a temperate forest ecosystem.

    PubMed

    Bagherzadeh, Ali; Brumme, Rainer; Beese, Friedrich

    2008-05-01

    To investigate the effect of silvicultural methods on forest floor C, N and elements stocks an experiment was carried out by sampling the forest floors of a 100-120-years-old species including beech, Norway spruce and mixed beech-spruce at the Solling forest, Germany. While the stocks of carbon and nitrogen in the forest floors of pure beech and spruce were significantly influenced by species specific differences of litter quality (p < 0.001), no significant differences were detected between pure and mixed species stands. Forest floor mass, some elements concentrations and C/nutrient ratios were significantly affected by tree species differences, while no clear dependency between pH and site specific effects was found among pure stands. Acid element concentrations in the forest floors of pure spruce were remarkably higher than the values obtained at beech stand, while the stocks were to some extent modified in mixed silviculture. The base-pump effect of beech significantly controlled variation between mono cultures on calcium stocks, while the acidifying effect of spruce in mixtures resulted in modification of Ca stocks of forest floors. The status of other nutrient elements at mixed species cultures due to variation in nutritional properties and composition of litter compared to pure species were between the range of values observed in mono cultures.

  11. Study of acidified ignitable liquid residues in fire debris by solid-phase microextraction with gas chromatography and mass spectrometry.

    PubMed

    Martín-Alberca, Carlos; García-Ruiz, Carmen; Delémont, Olivier

    2015-07-14

    The detection and identification of ignitable liquid residues in fire debris can be meaningful in fire investigations. However, background pyrolysis products and weathering hinder the identification and classification steps. In addition to those processes, the acidification of the ignitable liquids before the combustion process could make those tasks even more difficult. Nevertheless, there are no systematic studies assessing the extraction, analysis and composition of acidified ignitable liquid residues obtained from fire debris. In this work, a methodology for the study of acidified ignitable liquid residues in fire debris by solid-phase microextraction with gas chromatography and mass spectrometry is proposed. This methodology has been evaluated, first with simulated solutions (gasoline-sulphuric acid mixtures set on fire under controlled conditions), and then with analysis of samples from real fire debris obtained from 18 chemical ignition Molotov cocktails made with sulfuric acid and three different ignitable liquids (two types of gasoline and diesel fuel). In addition, the extensive modifications observed in chromatograms of acidified ignitable liquid residues regarding neat and weathered samples were studied. These alterations were produced by the combustion and acidification processes. As a consequence, tert-butylated compounds are proposed as diagnostic indicators for the identification of acidified gasoline in fire debris, even in strongly weathered samples. This article is protected by copyright. All rights reserved.

  12. 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.

  13. 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...

  14. Preservation of acidified cucumbers with a combination of fumaric acid and cinnamaldehyde that target lactic acid bacteria and yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The naturally occurring compound, fumaric acid, was evaluated as a potential preservative for the long-term storage of cucumbers. Fumaric acid inhibited growth of lactic acid bacteria (LAB) in an acidified cucumber juice medium model system resembling conditions that could allow preservation of cucu...

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

    PubMed

    Breidt, Fred; Hayes, Janet; McFeeters, Roger F

    2007-11-01

    Outbreaks of acid-resistant foodborne 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 that thermal treatments are needed to achieve a 5-log reduction in the numbers of Escherichia coli O157:H7, Listeria monocytogenes, or Salmonella enterica. For some acidified vegetable products with a pH of 3.3 or below, heat processing can result in unacceptable product quality. The purpose of this study was to determine the holding times needed to achieve a 5-log reduction in E. coli O157:H7, L. monocytogenes, and S. enterica strains in acidified vegetable products with acetic acid as the primary acidulant, a pH of 3.3 or below, and a minimum equilibrated temperature of 10 degrees C. We found E. coli O157:H7 to be the most acid-resistant microorganism for the conditions tested, with a predicted time to achieve a 5-log reduction in cell numbers at 10 degrees C of 5.7 days, compared with 2.1 days (51 h) for Salmonella or 0.5 days (11.2 h) for Listeria. At 25 degrees C, the E. coli O157:H7 population achieved a 5-log reduction in 1.4 days (34.3 h).

  16. 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 (...

  17. 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.

  18. A 125 year record of fluvial calcium flux from a temperate catchment: Interplay of climate, land-use change and atmospheric deposition

    NASA Astrophysics Data System (ADS)

    Worrall, F.; Howden, N. J. K.; Burt, T. P.

    2012-10-01

    SummaryThis paper analyses the world's longest fluvial record of water hardness and calcium (Ca) concentration. We used records of permanent and temporary hardness and river flow for the UK's River Thames (catchment area 9998 km2) to estimate annual Ca flux from the river since 1883. The Thames catchment has a mix of agricultural and urban land use; it is dominated by mineral soils with groundwater contributing around 60% of river flow. Since the late 1800s, the catchment has undergone widespread urbanisation and climate warming, but has also been subjected to large-scale land-use change, especially during World War II and agricultural intensification in the 1960s. Here, we use a range of time series methods to explore the relative importance of these drivers in determining catchment-scale biogeochemical response. Ca concentrations in the Thames rose to a peak in the late 1980s (106 mg Ca/l). The flux of Ca peaked in 1916 at 385 ktonnes Ca/yr; the minimum was in 1888 at 34 ktonnes Ca/yr. For both the annual average Ca concentration and the annual flux of Ca, there were significant increases with time; a significant positive memory effect relative to the previous year; and significant correlation with annual water yield. No significant correlation was found with either temperature or land use, but sulphate deposition was found to be significant. It was also possible, for a shorter time series, to show a significant relationship with inorganic nitrogen inputs into the catchment. We suggest that ionic inputs did not acidify the mineral soils of the catchment but did cause the leaching of metals, so we conclude that the decline in river Ca concentrations is caused by the decline in both S and N inputs.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Assessing the Spatial Relationships Between Hydrological Processes and Catchment Architecture at Multiple Scales

    NASA Astrophysics Data System (ADS)

    Ali, G.; Roy, A.; Thériault, R.; Sicotte, K.

    2008-12-01

    New statistical tools are needed in hydrology to improve our understanding of process heterogeneity and its relationship to catchment architecture. Specifically, the issue of spatial scale must be carefully considered while investigating hydrological processes, yet it is often invoked in a qualitative (catchment, hillslope and plot scales) rather than in a quantitative manner (distance or area assessments). In this paper, we applied a new approach, the PCNM (principal coordinates of neighbor matrices) method, for the search for dominant organizing scales of soil moisture in a humid temperate forested catchment. PCNM analysis provides a way of modeling spatial patterns by a combination of auto-correlated structures. This method has proven invaluable in ecology but is still not used in hydrology. PCNM could be a very powerful tool for depicting the spatial structure of hydrological state variables, the dynamics of which usually reflect processes dependent upon spatial connectivity and stormflow distribution between heterogeneous locations. We focused on three key- questions regarding processes and scales: (1) do catchment soil moisture patterns reflect the hierarchical scales of hydrological processes?, (2) is there a strong relationship between soil moisture patterns and topographic controls patterns?, and (3) are soil moisture patterns and their topographic controls across scales highly dependent upon hydro-meteorological factors? Data consisted of 11 surveys of soil moisture content at multiple depths in the 5.1 ha Hermine catchment (Laurentians, Canada). PCNM analysis was able to dissect the variance in soil moisture over four nested scales: very-large (1.1-1.6 ha), large (0.8-1.1 ha), meso (0.1-0.8 ha) and fine (less than 0.1 ha). The technique proved to be useful in searching for characteristic spatial scales, as the PCNM model explained between 87 and 98 % of the variance in the detrended soil moisture data apportioned into significant decreasing fractions

  7. Export of nitrogen from catchments: a worldwide analysis.

    PubMed

    Alvarez-Cobelas, M; Angeler, D G; Sánchez-Carrillo, S

    2008-11-01

    This study reviews nitrogen export rates from 946 rivers of the world to determine the influence of quantitative (runoff, rainfall, inhabitant density, catchment area, percentage of land use cover, airborne deposition, fertilizer input) and qualitative (dominant type of forest, occurrence of stagnant waterbodies, dominant land use, occurrence of point sources, runoff type) environmental factors on nitrogen fluxes. All fractions (total, nitrate, ammonia, dissolved organic and particulate organic) of nitrogen export showed a left-skewed distribution, which suggests a relatively pristine condition for most systems. Total nitrogen export showed the highest variability whereas total organic nitrogen export comprised the dominant fraction of export. Nitrogen export rates were only weakly explained by our qualitative and quantitative environmental variables. Our study suggests that the consideration of spatial and temporal scales is important for predicting nitrogen export rates using simple and easy-to-get environmental variables. Regionally based modelling approaches prove more useful than global-scale analyses.

  8. 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

  9. 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

  10. 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.

  11. Characterising water balance dynamics and different runoff components in a poorly gauged tropical catchment, Nicaragua

    NASA Astrophysics Data System (ADS)

    Calderon, Heyddy; Uhlenbrook, Stefan

    2014-05-01

    The water balance dynamics, groundwater flow systems and the runoff components of a tropical forested small catchment (46 km2) is the southwestern Pacific coast of Nicaragua were studied by a combination of hydrometry (observation of rainfall, runoff, evaporation and groundwater levels), geological characterisation (hydrogeological mapping, flow systems, characterization and Piper diagrams) and hydrochemical and isotopic tracers (chemograph analysis, 2- and 3-component hydrograph separation, discharge-hydrochemical hysteresis effects, and MWL). Although some methods can be considered standard in runoff generation research in temperate climate regions; to the best of our knowledge, this is one of the few studies that used the combination of these techniques in a tropical catchment of Central America. Runoff components were studied at different spatial and temporal scales, finding that different sources and temporal contributions are controlled by geology, catchment size, and dominant landscape elements. Two major groundwater flow systems were identified with different chemical and isotopic characteristics. Indication of moisture recycling in the upper catchment area was found based on d-excess analysis. Runoff components were studied at different spatial and temporal scales, demonstrating that different sources and temporal contributions are controlled by dominant landscape elements and precipitation distribution. Evidence of strong river-aquifer interactions in the lower part of the catchment was found. The results provide an in-depth understanding of the surface and groundwater contributions to stream flow and its temporal and spatial distribution, which indicate the importance of runoff generation areas upstream in the catchment and also the vulnerability of the alluvial aquifer to contamination. This provides the basis to develop realistic, evidence-based water management plans for this developing region.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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.

  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. Nutrient digestibility and mass balance in laying hens fed a commercial or acidifying diet.

    PubMed

    Wu-Haan, W; Powers, W J; Angel, C R; Hale, C E; Applegate, T J

    2007-04-01

    The objectives of the current study were to evaluate the effect of an acidifying diet (gypsum) combined with zeolite and slightly reduced crude protein (R) vs. a control diet (C) on nutrient retention in laying hens and compare 3 approaches to estimating nutrient excretion from hens: 1) mass balance calculation (feed nutrients - egg nutrient), 2) use of an indigestible marker with analyzed feed and excreta nutrient content, and 3) an environmental chamber that allowed for capturing all excreted and volatilized nutrients. Hens (n = 640) were allocated randomly to 8 environmental chambers for 3-wk periods. Excreta samples were collected at the end of each trial to estimate apparent retention of N, S, P, and Ca. No diet effects on apparent retention of N were observed (53.44%, P > 0.05). Apparent retention of S, P, and Ca decreased in hens fed R diet (18.7, - 11.4, and 22.6%, respectively) compared with hens fed the C diet (40.7, 0.3, and 28.6%, respectively; P < 0.05). Total N excretion from hens fed the C and R diet was not different (1.16 g/hen/d); however, mass of chamber N remaining in excreta following the 3-wk period was less from hens fed the C diet (1.27 kg) than from hens fed the R diet (1.43 kg). Gaseous emissions of NH(3) over the 3-wk period from hens fed the C diet (0.74 kg per chamber) were greater than emissions from hens fed the R diet (0.45 kg). The 3-wk S excretion mass (estimated using the calculation, indigestible marker, and environmental chamber methods, respectively) was greater from hens fed the R diet (1.85, 1.54, and 1.27 kg, respectively) compared with hens fed the C diet (0.24, 0.20, and 0.14 kg, respectively). The 3-wk P excretion was similar between diets (0.68 kg). Results demonstrate that feeding the acidified diet resulted in decreased N emissions, but because of the acidulant fed, greatly increased S excretion and emissions.

  2. 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

  3. Vegetation and water fluxes under Mediterranean mountain conditions. The Vallcebre research catchments (NE Spain)

    NASA Astrophysics Data System (ADS)

    Llorens, P.; Poyatos, R.; Muzylo, A.; Rubio, C. M.; Latron, J.; Delgado, J.; Gallart, F.

    2009-04-01

    The Vallcebre research catchments are located in a Mediterranean mountain area of the Pyrenean ranges (North Eastern Spain). These catchments were originally covered by Quercus pubescens but were deforested for agricultural use in the past. Nowadays they are covered by mesophyle grasses with spontaneous afforestation by Pinus sylvestris, covering 64% of the catchment area. In this context, different investigations studying water fluxes in the soil-vegetation-atmosphere continuum have been performed. The main objective of these studies is the analysis of the role of vegetation cover on the catchment water balance in a framework of climate and land use changes. The dynamics of transpiration and rainfall interception by Pinus sylvestris and Quercus pubescens, are investigated in terms of their dependence on meteorological conditions, on soil moisture and water table depth. Furthermore, the role of vegetation on catchment water balance is analysed. The results underline: (a) The importance of rainfall interception losses, representing about 24% of the bulk rainfall by the Scots pine and between 6 and 24%, by the Pubescent oak (depending on phenology), and the high temporal variability of this flux. (b) The effect of forest covers on soil moisture, which was apparent when comparing neighbouring soil moisture profiles under forest and meadows. (c) The differences in transpiration between species. Transpiration by Scots pines represented twice the value found in the nearby Pubescent oak stand. Scots pines showed a strong reduction of transpiration during dry summer periods, even in the studied area where the annual rainfall slightly exceeds the reference evapotranspiration. On the contrary, Pubescent oak was less affected by soil moisture deficits. Rainfall interception as well as trees transpiration processes have been modelled (Gash and Jarvis-type models respectively) at the plot scale with a twofold objective: the comprehension of each studied process and the analysis

  4. 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

  5. A perspective on stream-catchment connections

    USGS Publications Warehouse

    Bencala, Kenneth E.

    1993-01-01

    Ecological study of the hyporheic zone is leading to recognition of a need for additional hydrologic understanding. Some of this understanding can be obtained by viewing the hyporheic zone as a succession of isolated boxes adjacent to the stream. Further understanding, particularly relevant to catchment-scale ecology, may come from studies focussed on the fluid mechanics of the flow-path connections between streams and their catchments.

  6. A new perspective on catchment storage gained from a nested catchment experiment in Luxembourg (Europe)

    NASA Astrophysics Data System (ADS)

    Pfister, Laurent; Klaus, Julian; Hissler, Christophe; François Iffly, Jean; Gourdol, Laurent; Martinez-Carreras, Nuria; McDonnell, Jeffrey J.

    2014-05-01

    Recent hydrological process research focussed on how much water a catchment can store and how these catchments store and release water. Storage can be a valuable metric for catchment description, inter-comparison, and classification. Further storage controls catchment mixing, non-linearities in rainfall-runoff transformation and eco-hydrological processes. Various methods exist to determine catchment storage (e.g. natural tracer, soil moisture and groundwater data, hydrological models). Today it remains unclear what parts of the catchment storage are measured with the different models. Here we present a new hydrometric approach to answer the question how much water a catchment can store. We tested our approach in a dense hydro-climatological monitoring network that encompasses 16 recording streamgauges and 21 pluviographs in the Alzette River basin in Luxembourg (Europe). Catchment scales are ranging from 0.47 to 285 km2 and they have clean- and mixed combinations of distinct geologies ranging from schists to marls, sandstone, dolomite and limestone. Previous investigations in the area of interest have shown that geology largely controls winter runoff coefficients. Here, we focus at how catchment geology is ultimately affecting catchment storage. We used the approach of Sayama et al. (2011) to compute catchment dynamic storage changes for each winter season over the period 2002-2012 (based on precipitation as input; discharge and evapotranspiration as output). We determined dynamic storage changes for each winter semester (October to March) in all 16 catchments over the period 2002-2012. At the beginning of each hydrological winter season, all catchments showed similar trends in storage change. A few weeks into the winter season, catchments with lowest permeability (e.g. marls) started to plateau. The highest storage values were reached several months later in the season in catchments dominated by permeable substrate (e.g. sandstone). For most catchments, we found

  7. Topic: Catchment system dynamics: Processes and feedbacks

    NASA Astrophysics Data System (ADS)

    Keesstra, Saskia

    2015-04-01

    In this meeting we can talk about my main expertise: the focus of my research ocus revolves around understanding catchment system dynamics in a holistic way by incorporating both processes on hillslopes as well as in the river channel. Process knowledge enables explanation of the impact of natural and human drivers on the catchment systems and which consequences these drivers have for water and sediment connectivity. Improved understanding of the catchment sediment and water dynamics will empower sustainable land and river management and mitigate soil threats like erosion and off-side water and sediment accumulation with the help of nature's forces. To be able to understand the system dynamics of a catchment, you need to study the catchment system in a holistic way. In many studies only the hillslopes or even plots are studied; or only the channel. However, these systems are connected and should be evaluated together. When studying a catchment system any intervention to the system will create both on- as well as off sites effects, which should especially be taken into account when transferring science into policy regulations or management decisions.

  8. Simulating the effect of vegetation cover on the sediment yield of mediterranean catchments using SHETRAN

    NASA Astrophysics Data System (ADS)

    Lukey, B. T.; Sheffield, J.; Bathurst, J. C.; Lavabre, J.; Mathys, N.; Martin, C.

    1995-08-01

    The sediment yield of two catchments in southern France was modelled using the newly developed sediment code of SHETRAN. A fire in August 1990 denuded the Rimbaud catchment, providing an opportunity to study the effect of vegetation cover on sediment yield by running the model for both pre-and post-fire cases. Model output is in the form of upper and lower bounds on sediment discharge, reflecting the uncertainty in the erodibility of the soil. The results are encouraging since measured sediment discharge falls largely between the predicted bounds, and simulated sediment yield is dramatically lower for the catchment before the fire which matches observation. SHETRAN is also applied to the Laval catchment, which is subject to Badlands gulley erosion. Again using the principle of generating upper and lower bounds on sediment discharge, the model is shown to be capable of predicting the bulk sediment discharge over periods of months. To simulate the effect of reforestation, the model is run with vegetation cover equivalent to a neighbouring fully forested basin. The results obtained indicate that SHETRAN provides a powerful tool for predicting the impact of environmental change and land management on sediment yield.

  9. The role of bedrock groundwater in rainfall-runoff response at hillslope and catchment scales

    NASA Astrophysics Data System (ADS)

    Gabrielli, C. P.; McDonnell, J. J.; Jarvis, W. T.

    2012-07-01

    SummaryBedrock groundwater dynamics in headwater catchments are poorly understood and poorly characterized. Direct hydrometric measurements have been limited due to the logistical challenges associated with drilling through hard rock in steep, remote and often roadless terrain. We used a new portable bedrock drilling system to explore bedrock groundwater dynamics aimed at quantifying bedrock groundwater contributions to hillslope flow and catchment runoff. We present results from the Maimai M8 research catchment in New Zealand and Watershed 10 (WS10) at the H.J. Andrews Experimental Forest in Oregon, USA. Analysis of bedrock groundwater at Maimai, through a range of flow conditions, revealed that the bedrock water table remained below the soil-bedrock interface, indicating that the bedrock aquifer has minimal direct contributions to event-based hillslope runoff. However, the bedrock water table did respond significantly to storm events indicating that there is a direct connection between hillslope processes and the underlying bedrock aquifer. WS10 groundwater dynamics were dominated by fracture flow. A highly fractured and transmissive zone within the upper one meter of bedrock conducted rapid lateral subsurface stormflow and lateral discharge. The interaction of subsurface stormflow with bedrock storage directly influenced the measured hillslope response, solute transport and computed mean residence time. This research reveals bedrock groundwater to be an extremely dynamic component of the hillslope hydrological system and our comparative analysis illustrates the potential range of hydrological and geological controls on runoff generation in headwater catchments.

  10. Forest Resources

    SciTech Connect

    2016-06-01

    Forest biomass is an abundant biomass feedstock that complements the conventional forest use of wood for paper and wood materials. It may be utilized for bioenergy production, such as heat and electricity, as well as for biofuels and a variety of bioproducts, such as industrial chemicals, textiles, and other renewable materials. The resources within the 2016 Billion-Ton Report include primary forest resources, which are taken directly from timberland-only forests, removed from the land, and taken to the roadside.

  11. Forests fuel fish growth in freshwater deltas

    PubMed Central

    Tanentzap, Andrew J.; Szkokan-Emilson, Erik J.; Kielstra, Brian W.; Arts, Michael T.; Yan, Norman D.; Gunn, John M.

    2014-01-01

    Aquatic ecosystems are fuelled by biogeochemical inputs from surrounding lands and within-lake primary production. Disturbances that change these inputs may affect how aquatic ecosystems function and deliver services vital to humans. Here we test, using a forest cover gradient across eight separate catchments, whether disturbances that remove terrestrial biomass lower organic matter inputs into freshwater lakes, thereby reducing food web productivity. We focus on deltas formed at the stream-lake interface where terrestrial-derived particulate material is deposited. We find that organic matter export increases from more forested catchments, enhancing bacterial biomass. This transfers energy upwards through communities of heavier zooplankton, leading to a fourfold increase in weights of planktivorous young-of-the-year fish. At least 34% of fish biomass is supported by terrestrial primary production, increasing to 66% with greater forest cover. Habitat tracers confirm fish were closely associated with individual catchments, demonstrating that watershed protection and restoration increase biomass in critical life-stages of fish. PMID:24915965

  12. Quantifying stream temperature response to environmental change in a groundwater-dominated catchment, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    MacDonald, R.; Byrne, J. M.; Boon, S.

    2012-12-01

    The ecological significance of steam temperature response to environmental change has been discussed in many recent studies across a range of disciplines. We couple a stream energy and mass balance model with a catchment-scale hydrometeorological model to quantify stream temperature response to environmental change in a groundwater-dominated catchment. Given the importance of surface-subsurface interactions in simulating stream temperature, we propose a baseflow separation technique to parameterize these interactions within the model. This method forms the basis of a catchment-scale modelling approach designed specifically for data sparse regions. Using this approach we applied a sensitivity analysis to examine the effects of forest disturbance (harvest with riparian buffer) and climate change (mean air temperature and precipitation change for the 2040-2069 period) on stream temperature. We find that stream temperature following forest disturbance and climate change is primarily affected by a predicted shift towards earlier snowmelt runoff timing, which advances subsurface recharge early in the spring and subsequently decreases subsurface discharge in the summer, fall and winter. Changes in seasonal stream temperature regime may have important ecological consequences, particularly during the spawning and rearing stages of the salmonid lifecycle.

  13. Land cover controls the export of terminal electron acceptors from boreal catchments

    NASA Astrophysics Data System (ADS)

    Palviainen, Marjo; Lehtoranta, Jouni; Ekholm, Petri; Ruoho-Airola, Tuija; Kortelainen, Pirkko

    2015-04-01

    NO3, Mn, Fe and SO4 act as terminal electron acceptors (TEAs) modifying mineralization pathways and coupling biogeochemical cycles. Although single TEA concentrations and fluxes have been intensively studied, the factors regulating the simultaneous fluxes and molar ratios of TEAs are poorly elucidated. We studied the mean concentrations, exports and molar ratios of TEAs from 27 boreal catchments differing in land cover (percentage of agricultural land, peatland, forest and built-up area) in the years 2000-2011. TEA exports and molar ratios were strongly controlled by land cover and only little by atmospheric deposition. There were a great variability of the export of TEAs from different land cover classes. Fields produced the highest export of TEAs, particularly NO3. Peatland was linked to low NO3 and SO4 but high Fe exports. NO3, Mn and Fe exports from forests were low, SO4 having proportionally the highest export. Together, the percentages of field and peatland predicted 93%, 80%, 75% and 67% of the variation in the export of NO3, Mn, Fe and SO4, respectively. Our results showed that the export and molar ratios of TEAs in northern European boreal catchments are predominantly a function of land cover and catchment processes rather than atmospheric deposition. The variable export of TEAs having different availability and physical behavior may create different premises for anaerobic mineralization in downstream systems, which adds a new dimension to the link between terrestrial system, land use and environmental problems such as eutrophication and climate change.

  14. The influence of riparian evapotranspiration on stream hydrology and nitrogen retention in a subhumid Mediterranean catchment

    NASA Astrophysics Data System (ADS)

    Lupon, Anna; Bernal, Susana; Poblador, Sílvia; Martí, Eugènia; Sabater, Francesc

    2016-09-01

    Riparian evapotranspiration (ET) can influence stream hydrology at catchment scale by promoting the net loss of water from the stream towards the riparian zone (i.e., stream hydrological retention). However, the consequences of stream hydrological retention on nitrogen dynamics are not well understood. To fill this gap of knowledge, we investigated changes in riparian ET, stream discharge, and nutrient chemistry in two contiguous reaches (headwater and valley) with contrasted riparian forest size in a small forested Mediterranean catchment. Additionally, riparian groundwater level (hgw) was measured at the valley reach. The temporal pattern of riparian ET was similar between reaches, and was positively correlated with hgw (ρ = 0.60) and negatively correlated with net riparian groundwater inputs (ρ < -0.55). During the vegetative period, stream hydrological retention occurred mostly at the valley reach (59 % of the time), and was accompanied by in-stream nitrate release and ammonium uptake. During the dormant period, when the stream gained water from riparian groundwater, results showed small influences of riparian ET on stream hydrology and nitrogen concentrations. Despite being a small component of annual water budgets (4.5 %), our results highlight that riparian ET drives stream and groundwater hydrology in this Mediterranean catchment and, furthermore, question the potential of the riparian zone as a natural filter of nitrogen loads.

  15. Nitrite addition to acidified sludge significantly improves digestibility, toxic metal removal, dewaterability and pathogen reduction

    NASA Astrophysics Data System (ADS)

    Du, Fangzhou; Keller, Jürg; Yuan, Zhiguo; Batstone, Damien J.; Freguia, Stefano; Pikaar, Ilje

    2016-12-01

    Sludge management is a major issue for water utilities globally. Poor digestibility and dewaterability are the main factors determining the cost for sludge management, whereas pathogen and toxic metal concentrations limit beneficial reuse. In this study, the effects of low level nitrite addition to acidified sludge to simultaneously enhance digestibility, toxic metal removal, dewaterability and pathogen reduction were investigated. Waste activated sludge (WAS) from a full-scale waste water treatment plant was treated at pH 2 with 10 mg NO2‑-N/L for 5 h. Biochemical methane potential tests showed an increase in the methane production of 28%, corresponding to an improvement from 247 ± 8 L CH4/kg VS to 317 ± 1 L CH4/kg VS. The enhanced removal of toxic metals further increased the methane production by another 18% to 360 ± 6 L CH4/kg VS (a total increase of 46%). The solids content of dewatered sludge increased from 14.6 ± 1.4% in the control to 18.2 ± 0.8%. A 4-log reduction for both total coliforms and E. coli was achieved. Overall, this study highlights the potential of acidification with low level nitrite addition as an effective and simple method achieving multiple improvements in terms of sludge management.

  16. Nitrite addition to acidified sludge significantly improves digestibility, toxic metal removal, dewaterability and pathogen reduction

    PubMed Central

    Du, Fangzhou; Keller, Jürg; Yuan, Zhiguo; Batstone, Damien J.; Freguia, Stefano; Pikaar, Ilje

    2016-01-01

    Sludge management is a major issue for water utilities globally. Poor digestibility and dewaterability are the main factors determining the cost for sludge management, whereas pathogen and toxic metal concentrations limit beneficial reuse. In this study, the effects of low level nitrite addition to acidified sludge to simultaneously enhance digestibility, toxic metal removal, dewaterability and pathogen reduction were investigated. Waste activated sludge (WAS) from a full-scale waste water treatment plant was treated at pH 2 with 10 mg NO2−-N/L for 5 h. Biochemical methane potential tests showed an increase in the methane production of 28%, corresponding to an improvement from 247 ± 8 L CH4/kg VS to 317 ± 1 L CH4/kg VS. The enhanced removal of toxic metals further increased the methane production by another 18% to 360 ± 6 L CH4/kg VS (a total increase of 46%). The solids content of dewatered sludge increased from 14.6 ± 1.4% in the control to 18.2 ± 0.8%. A 4-log reduction for both total coliforms and E. coli was achieved. Overall, this study highlights the potential of acidification with low level nitrite addition as an effective and simple method achieving multiple improvements in terms of sludge management. PMID:28004811

  17. Treatment of Acidified Blood Using Reduced Osmolarity Mixed-Base Solutions

    PubMed Central

    Mason, Thomas G.; Kraut, Jeffrey A.

    2016-01-01

    We hypothesize that reduced osmolarity mixed-base (ROMB) solutions can potentially serve as customizable treatments for acidoses, going beyond standard solutions in clinical use, such as 1.0 M sodium bicarbonate. Through in silico quantitative modeling, by treating acidified canine blood using ROMB solutions, and by performing blood-gas and optical microscopy measurements in vitro, we demonstrate that ROMB solutions having a high proportion of a strong base, such as disodium carbonate or sodium hydroxide, can be effective in reducing carbon dioxide pressure PCO2 while raising pH and bicarbonate ion concentration without causing significant osmotic damage to red blood cells, which can occur during rapid administration of hypertonic solutions of weak bases. These results suggest that a ROMB solution, which is composed mostly of a strong base, could be administered in a safe and effective manner, when compared to a hypertonic solution of sodium bicarbonate. Because of the reduced osmolarity and the customizable content of strong base in ROMB solutions, this approach differs from prior approaches involving hypertonic solutions that only considered a single molar ratio of strong to weak base. Our calculations and measurements suggest that custom-tailored ROMB solutions merit consideration as potentially efficacious treatments for specific types of acidosis, particularly acute metabolic acidosis and acute respiratory acidosis. PMID:28082905

  18. Rheology and stability of acidified food emulsions treated with high pressure.

    PubMed

    Arora, Akshay; Chism, Grady W; Shellhammer, Thomas H

    2003-04-23

    The stability and rheology of acidified model oil-in-water emulsions (pH 3.6 +/- 0.1) were evaluated before and after high-pressure treatments. Varying concentrations of canola oil (0-50% w/w), whey protein isolate, polysorbate 60, soy lecithin (0.1-1.5% w/w each), and xanthan (0.0-0.2% w/w) were chosen. Exposure to high pressures (up to 800 MPa for 5 min at 30 degrees C) did not significantly affect the equivalent surface mean diameter D[3,2], flow behavior, and viscoelasticity of the whey protein isolate and polysorbate 60-stabilized emulsions. Pressure treatments had negligible effects on emulsion stability in these systems, except when xanthan (0.2% w/w) was present in which pressure improved the stability of polysorbate 60-stabilized emulsions. Soy lecithin-stabilized emulsions had larger mean particles sizes and lower emulsion volume indices than the others, indicating potential instability, and application of pressure further destabilized these emulsions.

  19. 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.

  20. 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.

  1. The behavior of rare earth elements in naturally and anthropogenically acidified waters

    USGS Publications Warehouse

    Wood, Scott A.; Gammons, Christopher H.; Parker, Stephen R.

    2006-01-01

    In this paper, the behavior of rare earth elements (REE) in a watershed impacted by acid-mine drainage (Fisher Creek, Montana) is compared to that in a volcanically acidified watershed (Rio Agrio and Lake Caviahue, Argentina). The REE behave conservatively in acidic waters with pH values less than approximately 5.5. However, above pH 5.5, REE concentrations are controlled by adsorption onto or co-precipitation with a variety of Fe or Al oxyhydroxides. The heavy REE partition to a greater extent into the solid phase than the light REE as pH rises above 6. Concentrations of REE exhibit diel (24-h) cycling in waters that were initially acidic, but have become neutralized downstream. In Fisher Creek, at the most downstream sampling station investigated (pH 6.8), concentrations of dissolved REE were 190–840% higher in the early morning versus the late afternoon. This cycling can be related to temperature-dependent, cyclic adsorption–desorption of REE onto hydrous ferric or aluminum oxide or both. Similar but gentler diel cycling of the REE was found at Rio Agrio. The existence of such cycling has important ramifications for the study of REE in natural waters.

  2. 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.

  3. 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.

  4. Alterations of Fractures in Carbonate Rocks by CO2-Acidified Brines.

    PubMed

    Deng, Hang; Fitts, Jeffrey P; Crandall, Dustin; McIntyre, Dustin; Peters, Catherine A

    2015-08-18

    Fractures in geological formations may enable migration of environmentally relevant fluids, as in leakage of CO2 through caprocks in geologic carbon sequestration. We investigated geochemically induced alterations of fracture geometry in Indiana Limestone specimens. Experiments were the first of their kind, with periodic high-resolution imaging using X-ray computed tomography (xCT) scanning while maintaining high pore pressure (100 bar). We studied two CO2-acidified brines having the same pH (3.3) and comparable thermodynamic disequilibrium but different equilibrated pressures of CO2 (PCO2 values of 12 and 77 bar). High-PCO2 brine has a faster calcite dissolution kinetic rate because of the accelerating effect of carbonic acid. Contrary to expectations, dissolution extents were comparable in the two experiments. However, progressive xCT images revealed extensive channelization for high PCO2, explained by strong positive feedback between ongoing flow and reaction. The pronounced channel increasingly directed flow to a small region of the fracture, which explains why the overall dissolution was lower than expected. Despite this, flow simulations revealed large increases in permeability in the high-PCO2 experiment. This study shows that the permeability evolution of dissolving fractures will be larger for faster-reacting fluids. The overall mechanism is not because more rock dissolves, as would be commonly assumed, but because of accelerated fracture channelization.

  5. 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.

  6. Anthropogenic oligotrophication via liming: Long-term phosphorus trends in acidified, limed, and neutral reference lakes in Sweden.

    PubMed

    Hu, Qian; Huser, Brian J

    2014-01-01

    Restoration of acidified lakes by liming does not, in many cases, improve productivity to a pre-acidified state. We hypothesize that the poor recovery detected in many of these lakes is due to constrained in-lake phosphorous (P) cycling caused by enhanced precipitation of metals in higher pH, limed waters. Long-term (1990-2012) data for 65 limed, circum-neutral (pH 6-8), and acidified lakes in Sweden were analyzed to determine trends for P and potential drivers of these trends. Limed lakes not only had lower mean values and stronger decreasing trends for total P than non-limed lakes, but they also had the highest percentage of decreasing trends (85 %). A P release factor (Hypolimnetic P/Epilimnetic P) was developed to elucidate differences in internal P cycling between lake groups. Consistently, lower P release factors in limed lakes show limitation of internal P cycling during summer months that may be a factor limiting P bioavailability and thus productivity of these systems.

  7. Variation in throughfall deposition across a deciduous beech (Fagus sylvatica L.) forest edge in Flanders.

    PubMed

    Devlaeminck, Rebecca; De Schrijver, An; Hermy, Martin

    2005-01-20

    Throughfall deposition and canopy exchange of acidifying and eutrophying compounds and major base cations were studied by means of throughfall analysis in a deciduous beech (Fagus sylvatica L.) forest edge in Belgium over a period of 1 year. Throughfall fluxes of Cl(-), NH(4)(+) and Na(+) were significantly elevated at the forest edge compared to the forest interior. As no edge effect on throughfall water volume could be detected, the observed edge enhancement effects were mainly due to dry deposition and canopy exchange patterns. Indeed, there was an elevated dry deposition of Cl(-), Na(+), K(+), Ca(2+) and Mg(2+) up to 50 m from the field/forest border. Within the forest, throughfall and dry deposition of SO(4)(2-) were highly variable and no significant differences were observed between the forest edge and the forest interior. Leaching of K(+) and Ca(2+) was reduced in the forest edge up to a distance of 30 m from the border. The measured nitrogen and acidic depositions far exceeded the current Flemish critical loads with respect to the protection of biodiversity in forests, especially at the forest edge. This points to an urgent need for controlling emissions as well as the need to consider the elevated deposition load in forest edges when calculating the critical loads in forests.

  8. Soil Hydrologic Response and Nutrient Movement in Three Small Tropical Catchments

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    The movement of water over and through soils by storm-generated flowpaths in tropical forests not only mediates nutrient movement and physical weathering, but also potentially influences vegetation growth and dynamics with seasonally dry or saturated soil conditions. However, few small-scale catchment studies (10-1000ha) have produced a comprehensive, standardized dataset on soil hydrologic properties among tropical forest catchments, due in part to complexities within tropical systems, and to inconsistencies in methods, data collection, and/or analyses. In response, this study has utilized the global, standardized network of forest dynamics plots of the Center for Tropical Forest Science (CTFS) for the rapid assessment of soil saturated hydraulic conductivity (Ks) and the water chemistry from storm-generated flowpaths. Ks measurements at varying depths help in testing Elsenbeer's (2001) functional classification continuum of tropical forest soilscapes and resulting hydrologic flowpaths. In Barro Colorado Island, Panama, Ks decreased rapidly with soil depth where horizontal surface and near-surface flowpaths were most prevalent. Ks measurements in Yasuni National Park, Ecuador indicated limited vertical movement of water at depths >15cm due to an impermeable soil layer. Ks measurements from Lambir Hills National Park, Malaysia, represented both ends of the continuum due to variability in soil type and lithology. In relation to soil hydrology and hydrological flowpaths, runoff chemistry at Yasuni reveals a general pattern of increased nutrient export as water moves through the canopy and over the soil surface, with concentrations of K+ increasing significantly in throughfall, and concentrations of both K+, and NO3- remaining high in overland flow. The results from the composite overland flow samples may indicate a more open nutrient cycle in tropical forest environments than has been suggested from earlier studies using radioactively labeled isotopes.

  9. Forest-Water Feedbacks Under a Changing Climate

    NASA Astrophysics Data System (ADS)

    Creed, I. F.; Hwang, T.

    2015-12-01

    Among the most valuable products produced by forests are the ecosystem services of safe and reliable water supplies. The provision of these ecosystem services on forested landscapes is inherently linked to forest condition. Climate change and associated hydrological intensification may affect forest water use (green water) and runoff generation (blue water) in the temperate forest biome of eastern North America. For the time period from the 1980s to present, a period with significant climate warming, we used a network of long-term catchment study sites nested within the temperate forest biome to explore forest-water feedbacks in response to climate change. Satellite remote sensing was used to track changes in forest phenology and forest productivity, and catchment meteorological and discharge records were used to track changes in the magnitude and timing of forest water yields. Forest responses to climate change varied along a latitudinal gradient. The magnitude of annual water yields declined at all study sites. The timing of peak discharge was measured by the center of mass (i.e., 50th percentile), and the narrowing or widening of discharge periods was measured by the coefficient of dispersion (i.e., 75th - 25th over 50th percentile) of water yield. For the vernal window, we observed subtle and systematic changes with a shift to later peaks in the center of mass of spring discharge and a widening of the spring discharge period (i.e., less peaked flows). For the autumnal window, we observed less subtle, non-systematic changes with a shift to later peaks above 45 degrees latitude but earlier peaks below 45 degrees latitude, and a narrowing of the fall discharge period (i.e., more peaked flows). The time shift and widening of vernal and autumnal windows are likely caused by asymmetric responses of forest water use (green water) and runoff generation (blue water) to climate warming. These disruptions in forest-water coupling are likely to have significant

  10. The contribution of atmospheric deposition and forest harvesting to forest soil acidification in China since 1980

    NASA Astrophysics Data System (ADS)

    Zhu, Qichao; De Vries, Wim; Liu, Xuejun; Zeng, Mufan; Hao, Tianxiang; Du, Enzai; Zhang, Fusuo; Shen, Jianbo

    2016-12-01

    Soils below croplands and grasslands have acidified significantly in China since the 1980s in terms of pH decline in response to acid inputs caused by intensified fertilizer application and/or acid deposition. However, it is unclear what the rate is of pH decline of forest soils in China in response to enhanced acid deposition and wood production over the same period. We therefore gathered soil pH data from the Second National Soil Inventory of China and publications from the China National Knowledge Infrastructure (CNKI) database in 1981-1985 and 2006-2010, respectively, to evaluate the long-term change of pH values in forest soils. We found that soil pH decreased on average by 0.36 units in the period 1981-1985 to 2006-2010., with most serious pH decline occurring in southwest China (0.63 pH units). The soil type with the strongest pH decline was the semi-Luvisol (0.44 pH units). The decrease in pH was significantly correlated with the acid input induced by atmospheric deposition and forest harvesting. On average, the contribution of atmospheric deposition to the total acid input was estimated at 84% whereas element uptake (due to forest wood growth and harvest) contributed 16% only. Atmospheric deposition is thus the major driver for the significant forest soil acidification across China.

  11. Catchment biophysical drivers of streamflow characteristics

    NASA Astrophysics Data System (ADS)

    Trancoso, R.

    2015-12-01

    The characteristics of streamflow reflect the co-evolution of climate, soils, topography and vegetation of catchments. Hydrological metrics or signatures can represent the long-term behaviour and integrate the influence of all the streamflow drivers. Although this sort of relationship has been developed in regional studies exploring prediction of Flow Duration Curves and other streamflow metrics, little is known about the controls of other key streamflow characteristics especially in continent scale. This study aims to understand how catchment biophysical variables control key hydrological metrics such as baseflow index, elasticity of streamflow to rainfall variability and intermittency in continent scale and regionally. We used a set of catchment biophysical variables to model key streamflow signatures using multivariate power-law and beta regressions in 355 catchments located along the eastern Australian seaboard. Streamflow signatures were derived from daily streamflow time series data from 1980 to 2013. We tested 52 catchment biophysical characteristics related to climate, soil, topography, geography, geomorphology, vegetation and land-cover as predictors of the streamflow signatures. The prediction R-squared ranged from 63 to 72% when relationships are built in continent scale, but can be greater than 80% when regressions are regionalised. The interpretation of the modelled relationships offers new insights regarding the controls of flow characteristics.

  12. What makes catchment management groups "tick"?

    PubMed

    Oliver, P

    2001-01-01

    The work of catchment management groups throughout Australia represents a significant economic and social investment in natural resource management. Institutional structures and policies, the role of on-ground coordinators, facilitation processes, citizen participation and social capital are critical factors influencing the success of catchment management groups. From a participant-researcher viewpoint, this paper signposts research directions and themes that are being pursued from the participant/coordinator, catchment group, and lead government/non-government agency perspective on the influence of these factors on the success of a catchment management group in the Pumicestone Region of Southeast Queensland, Australia. Research directions, themes and discussion/reflection points for practitioners include--the importance of understanding milieu; motivation; success; having fun; "networking networks"; involvement of "nontraditional" stakeholders; development of stakeholder/participant partnerships; learning from other practitioners; methods of stakeholder/participant representation; evaluation; the need for guiding principles or philosophy; the equivalence of planning, implementation, evaluation, and resourcing; catchments as fundamental units of Nature; continuity of support for groups; recognising a new role for government; working with existing networks; and the need for an eclectic approach to natural resource management.

  13. Frequent summer droughts homogenize landscape vegetation patterns at the catchment scale

    NASA Astrophysics Data System (ADS)

    Hwang, T.; Band, L. E.; Miniat, C. F.; Song, C.

    2013-12-01

    Mountain watersheds are primary sources of freshwater, carbon sequestration, and other ecosystem services. There is significant interest in the effects of climate change and variability on the patterns and processes of these services over short to long time scales. Forest ecosystems are sensitive to interannual to long-term hydroclimate variability and they adjust leaf area and duration in response to water or nutrient availability. Therefore, much of the impact of hydroclimate variability and resulting water yield is manifested in vegetation dynamics in space and time since they provide 'a window into the underlying water balance' (Sivapalan, 2005). Landsat TM provides a three-decade multispectral imagery record which enables us to estimate changes in landscape vegetation patterns at fine resolution (30 m) over the period of global warming. We characterize the catchment-scale vegetation patterns with the ';hydrologic vegetation gradient (HVG)' (defined as the gradient of the normalized difference vegetation index (NDVI) along hydrologic flowpaths; Hwang et al., 2012) and the standard deviations of NDVI from historic Landsat TM images at six preserved headwater catchments in Coweeta Hydrologic Laboratory, NC. We also analyze long-term seasonal water balances and low flow patterns from observed hydrologic records. We found that vegetation gradients along hydrologic flowpaths have decreased with hydroclimate change due to the decreases in upslope subsidies. This study shows that forest ecosystems are responding to the variability in hydroclimate regime rather than the mean, especially to drought. This study provides mechanistic understanding of shifts in hydrologic and ecologic regimes in humid mountainous landscapes with hydroclimate change. It also presents the potential to use emergent vegetation patterns in space and time for the inference of long-term hydrologic behavior. Figure 1. Temporal patterns of the hydrologic vegetation gradient and standard deviations

  14. Changing trends of rainfall and sediment fluxes in the Kinta River catchment, Malaysia

    NASA Astrophysics Data System (ADS)

    Ismail, W. R.; Hashim, M.

    2015-03-01

    The Kinta River, draining an area of 2566 km2, originates in the Korbu Mountain in Perak, Malaysia, and flows through heterogeneous, mixed land uses ranging from extensive forests to mining, rubber and oil palm plantations, and urban development. A land use change analysis of the Kinta River catchment was carried out together with assessment of the long-term trend in rainfall and sediment fluxes. The Mann-Kendall test was used to examine and assess the long-term trends in rainfall and its relationship with the sediment discharge trend. The land use analysis shows that forests, water bodies and mining land declined whilst built and agricultural land use increased significantly. This has influenced the sediment flux of the catchment. However, most of the rainfall stations and river gauging stations are experiencing an increasing trends, except at Kinta river at Tg. Rambutan. Sediment flux shows a net erosion for the period from 1961 to 1969. The total annual sediment discharge in the Kinta River catchment was low with an average rate of 1,757 t/km2/year. From 1970 to 1985, the annual sediment yield rose to an average rate of 4062 t/km2/year. Afterwards, from 1986 to 1993, the total annual sediment discharge decreased to an average rate of 1,306 t/km2/year and increased back during the period 1994 to 2000 to 2109 t/km2/year. From 2001 to 2006 the average sediment flux rate declined to 865 t/km2/year. The decline was almost 80% from the 1970s. High sediment flux in the early 1970s is partly associated with reduced tin mining activities in the area. This decreasing trend in sediment delivery leaving the Kinta River catchment is expected to continue dropping in the future.

  15. Investigation of Biogeochemical Functional Proxies in Headwater Streams Across a Range of Channel and Catchment Alterations

    NASA Astrophysics Data System (ADS)

    Berkowitz, Jacob F.; Summers, Elizabeth A.; Noble, Chris V.; White, John R.; DeLaune, Ronald D.

    2014-03-01

    Historically, headwater streams received limited protection and were subjected to extensive alteration from logging, farming, mining, and development activities. Despite these alterations, headwater streams provide essential ecological functions. This study examines proxy measures of biogeochemical function across a range of catchment alterations by tracking nutrient cycling (i.e., inputs, processing, and stream loading) with leaf litter fall, leaf litter decomposition, and water quality parameters. Nutrient input and processing remained highest in second growth forests (the least altered areas within the region), while recently altered locations transported higher loads of nutrients, sediments, and conductivity. Biogeochemical functional proxies of C and N input and processing significantly, positively correlated with rapid assessment results (Pearson coefficient = 0.67-0.81; P = 0.002-0.016). Additionally, stream loading equations demonstrate that N and P transport, sediment, and specific conductivity negatively correlated with rapid assessment scores (Pearson coefficient = 0.56-0.81; P = 0.002-0.048). The observed increase in stream loading with lower rapid assessment scores indicates that catchment alterations impact stream chemistry and that rapid assessments provide useful proxy measures of function in headwater ecosystems. Significant differences in nutrient processing, stream loading, water quality, and rapid assessment results were also observed between recently altered (e.g., mined) headwater streams and older forested catchments (Mann-Whitney U = 24; P = 0.01-0.024). Findings demonstrate that biogeochemical function is reduced in altered catchments, and rapid assessment scores respond to a combination of alteration type and recovery time. An analysis examining time and economic requirements of proxy measurements highlights the benefits of rapid assessment methods in evaluating biogeochemical functions.

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

    PubMed

    Juneja, Vijay K; Baker, David A; Thippareddi, H; Snyder, O Peter; Mohr, Tim B

    2013-01-01

    The ability of Clostridium perfringens to germinate and grow in acidified ground beef as well as in 10 commercially prepared acidified beef, pork, and poultry products was assessed. The pH of ground beef was adjusted with organic vinegar to achieve various pH values between 5.0 and 5.6; the pH of the commercial products ranged from 4.74 to 6.35. Products were inoculated with a three-strain cocktail of C. perfringens spores to achieve ca. 2-log (low) or 4-log (high) inoculum levels, vacuum packaged, and cooled exponentially from 54.4 to 7.2°C for 6, 9, 12, 15, 18, or 21 h to simulate abusive cooling; the U.S. Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS) recommends a cooling time of 6.5 h. Total germinated C. perfringens populations were determined after plating on tryptose-sulfite-cycloserine agar and incubating the plates anaerobically at 37°C for 48 h. In addition, C. perfringens growth from spores was assessed at an isothermal temperature of 44°C. Growth from spores was inhibited in ground beef with a pH of 5.5 or below, even during extended cooling from 54.4 to 7.2°C in 21 h. In ground beef with a pH of 5.6, the growth was >1 log after 18 h of cooling from 54.4 to 7.2°C. However, 15 h of cooling controlled the growth to <1 log, regardless of the inoculum level. In addition, no growth was observed in any product with a pH ranging from 4.74 to 5.17, both during exponential abusive cooling periods of up to 21 h and during storage for 21 h at 44°C. While <1-log growth of C. perfringens from spores was observed in the pH 5.63 product cooled exponentially from 54.4 to 7.2°C in 15 h or less, the pH 6.35 product supported growth, even after 6 h of cooling from 54.4 to 7.2°C. These challenge tests demonstrate that adjustment of ground beef to pH of 5.5 or less and of barbeque products to pH of 5.63 or less inhibits C. perfringens spore germination and outgrowth during extended cooling periods from 54.4 to 7.2°C up to 15 h. Therefore

  17. Land use/land cover change and implications for ecosystems services in the Likangala River Catchment, Malawi

    NASA Astrophysics Data System (ADS)

    Pullanikkatil, Deepa; Palamuleni, Lobina G.; Ruhiiga, Tabukeli M.

    2016-06-01

    Likangala River catchment in Zomba District of Southern Malawi is important for water resources, agriculture and provides many ecosystem services. Provisioning ecosystem services accrued by the populations within the catchment include water, fish, medicinal plants and timber among others. In spite of its importance, the River catchment is under threat from anthropogenic activities and land use change. This paper studies land uses and land cover change in the catchment and how the changes have impacted on the ecosystem services. Landsat 5 and 8 images (1984, 1994, 2005 and 2013) were used to map land cover change and subsequent inventorying of provisioning ecosystem services. Participatory Geographic Information Systems and Focus group discussions were conducted to identify provisioning ecosystems services that communities benefit from the catchment and indicate these on the map. Post classification comparisons indicate that since 1984, there has been a decline in woodlands from 135.3 km2 in 1984 to 15.5 km2 in 2013 while urban areas increased from 9.8 km2 to 23.8 km2 in 2013. Communities indicated that provisioning ecosystems services such as forest products, wild animals and fruits and medicinal plants have been declining over the years. In addition, evidence of catchment degradation through waste disposal, illegal sand mining, deforestation and farming on marginal lands were observed. Population growth, urbanization and demand for agricultural lands have contributed to this land use and land cover change. The study suggests addressing catchment degradation through integrated method where an ecosystems approach is used. Thus, both the proximate and underlying driving factors of land-use and land cover change need to be addressed in order to sustainably reduce ecosystem degradation.

  18. Within-catchment variation in regulation of water use by eucalypts, and the roles of stomatal anatomy and physiology

    NASA Astrophysics Data System (ADS)

    Gharun, Mana; Turnbull, Tarryn; Adams, Mark

    2014-05-01

    Understanding how environmental cues impact water use of forested catchments is crucial for accurate calculation of water balance and effective catchment management in terrestrial ecosystems. We characterised structural and physiological properties of leaves and canopies of Eucalyptus delegatensis, E. pauciflora and E. radiata, the most common species in high-country catchments in temperate Australia. These properties were related to whole-tree water transport to assess differences in water use strategies among the three species. Stomatal conductance, instantaneous transpiration efficiency, stomatal occlusion (through cuticular ledges) and leaf area index differed significantly among species. Whole-tree water use of all species was strongly coupled to changes in vapour pressure deficit (VPD) and photosynthetically active radiation (Q), yet stomatal closure reduced water transport at VPD > 1 kPa in all species, even when soil water was not limiting. The observed differences in leaf traits and related water use strategies reflect species-specific adaptations to dominant environmental conditions within the landscape matrix of catchments. The generalist E. radiata seems to follow an opportunistic, while the two more spatially restricted species have adopted a pessimistic water use strategy. Catchment-scale models of carbon and water fluxes will need to reflect such variation in structure and function, if they are to fully capture species effects on water balance and yield.

  19. Strong Ion Regulatory Abilities Enable the Crab Xenograpsus testudinatus to Inhabit Highly Acidified Marine Vent Systems

    PubMed Central

    Hu, Marian Y.; Guh, Ying-Jey; Shao, Yi-Ta; Kuan, Pou-Long; Chen, Guan-Lin; Lee, Jay-Ron; Jeng, Ming-Shiou; Tseng, Yung-Che

    2016-01-01

    Hydrothermal vent organisms have evolved physiological adaptations to cope with extreme abiotic conditions including temperature and pH. To date, acid-base regulatory abilities of vent organisms are poorly investigated, although this physiological feature is essential for survival in low pH environments. We report the acid-base regulatory mechanisms of a hydrothermal vent crab, Xenograpsus testudinatus, endemic to highly acidic shallow-water vent habitats with average environment pH-values ranging between 5.4 and 6.6. Within a few hours, X. testudinatus restores extracellular pH (pHe) in response to environmental acidification of pH 6.5 (1.78 kPa pCO2) accompanied by an increase in blood HCO3- levels from 8.8 ± 0.3 to 31 ± 6 mM. Branchial Na+/K+-ATPase (NKA) and V-type H+-ATPase (VHA), the major ion pumps involved in branchial acid-base regulation, showed dynamic increases in response to acidified conditions on the mRNA, protein and activity level. Immunohistochemical analyses demonstrate the presence of NKA in basolateral membranes, whereas the VHA is predominantly localized in cytoplasmic vesicles of branchial epithelial- and pillar-cells. X. testudinatus is closely related to other strong osmo-regulating brachyurans, which is also reflected in the phylogeny of the NKA. Accordingly, our results suggest that the evolution of strong ion regulatory abilities in brachyuran crabs that allowed the occupation of ecological niches in euryhaline, freshwater, and terrestrial habitats are probably also linked to substantial acid-base regulatory abilities. This physiological trait allowed X. testudinatus to successfully inhabit one of the world's most acidic marine environments. PMID:26869933

  20. Multiphase reactivity of gaseous hydroperoxide oligomers produced from isoprene ozonolysis in the presence of acidified aerosols

    NASA Astrophysics Data System (ADS)

    Riva, Matthieu; Budisulistiorini, Sri Hapsari; Zhang, Zhenfa; Gold, Avram; Thornton, Joel A.; Turpin, Barbara J.; Surratt, Jason D.

    2017-03-01

    Ozonolysis of alkenes results in the formation of primary ozonides (POZs), which can subsequently decompose into carbonyl compounds and stabilized Criegee intermediates (sCIs). The sCIs generated from isoprene ozonolysis include the simplest congener, formaldehyde oxide (CH2OO), and isomers of C4-sCI. Although the bimolecular reaction with H2O is expected to be the main fate of sCIs, it was reported that sCIs can also react with carboxylic acids and/or organic hydroperoxides leading to gas-phase oligomeric compounds. While the impact of the gas-phase composition (H2O, sCI scavenger) on the formation of such products was recently studied, their fate remains unclear. In the present work, formation of oligomeric hydroperoxides from isoprene ozonolysis, proposed as reaction products composed of the sCI as a chain unit and formed from the insertion of sCI into a hydroperoxide or a carboxylic acid, was systematically examined in the presence of aerosol with varying compositions. The effect of hydroxyl (OH) radicals on the gas- and particle-phase compositions was investigated using diethyl ether as an OH radical scavenger. Thirty-four oligomeric compounds resulting from the insertion of sCIs into organic hydroperoxides or carboxylic acids were identified using iodide chemical ionization high-resolution mass spectrometry. Large reactive uptake onto acidified sulfate aerosol was observed for most of the characterized gaseous oligomeric species, whereas the presence of organic coatings and the lack of aerosol water significantly reduced or halted the reactive uptake of these species. These results indicate that highly oxidized molecules, such as hydroperoxides, could undergo multiphase reactions, which are significantly influenced by the chemical composition of seed aerosol. Furthermore, in addition to functionalization and accretion, decomposition and re-volatilization should be considered in SOA formation.

  1. Trends in emissions of acidifying species in Asia, 1985-1997.

    SciTech Connect

    Streets, D. G.; Tsai, N. Y.; Akimoto, H.; Oka, K.

    2000-05-31

    Acid deposition is a serious problem throughout much of Asia. Emissions of sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) have been increasing steadily, as nations strive to increase their levels of economic development. Coal and fuel oil have been the main choices for powering industrial development; and, until recently, only a few countries (notably Japan and Taiwan) had taken significant steps to avert the atmospheric emissions that accompany fuel combustion. This paper discusses trends in emissions of SO{sub 2} and NO{sub x} that have occurred in Asian countries in the period 1985--1997, using results from the RAINS-ASIA computer model and energy-use trends from the IEA Energy Statistics and Balances database. Emissions of SO{sub 2} in Asia grew from 26.6 Tg in 1985 to 33.7 Tg in 1990 and to 39.2 Tg in 1997. Though SO{sub 2} emissions used to grow as fast as fossil-fuel use, recent limitations on the sulfur content of coal and oil have slowed the growth. The annual-average emissions growth between 1990 and 1997 was only 1.1%, considerably less than the economic growth rate. Emissions of NO{sub x}, on the other hand, continue to grow rapidly, from 14.1 Tg in 1985 to 18.7 Tg in 1990 and 28.5 Tg in 1997, with no signs of abating. Thus, though SO{sub 2} remains the major contributor to acidifying emissions in Asia, the role of NO{sub x}, will become more and more important in the future.

  2. Disrupting Hypoxia-Induced Bicarbonate Transport Acidifies Tumor Cells and Suppresses Tumor Growth.

    PubMed

    McIntyre, Alan; Hulikova, Alzbeta; Ledaki, Ioanna; Snell, Cameron; Singleton, Dean; Steers, Graham; Seden, Peter; Jones, Dylan; Bridges, Esther; Wigfield, Simon; Li, Ji-Liang; Russell, Angela; Swietach, Pawel; Harris, Adrian L

    2016-07-01

    Tumor hypoxia is associated clinically with therapeutic resistance and poor patient outcomes. One feature of tumor hypoxia is activated expression of carbonic anhydrase IX (CA9), a regulator of pH and tumor growth. In this study, we investigated the hypothesis that impeding the reuptake of bicarbonate produced extracellularly by CA9 could exacerbate the intracellular acidity produced by hypoxic conditions, perhaps compromising cell growth and viability as a result. In 8 of 10 cancer cell lines, we found that hypoxia induced the expression of at least one bicarbonate transporter. The most robust and frequent inductions were of the sodium-driven bicarbonate transporters SLC4A4 and SLC4A9, which rely upon both HIF1α and HIF2α activity for their expression. In cancer cell spheroids, SLC4A4 or SLC4A9 disruption by either genetic or pharmaceutical approaches acidified intracellular pH and reduced cell growth. Furthermore, treatment of spheroids with S0859, a small-molecule inhibitor of sodium-driven bicarbonate transporters, increased apoptosis in the cell lines tested. Finally, RNAi-mediated attenuation of SLC4A9 increased apoptosis in MDA-MB-231 breast cancer spheroids and dramatically reduced growth of MDA-MB-231 breast tumors or U87 gliomas in murine xenografts. Our findings suggest that disrupting pH homeostasis by blocking bicarbonate import might broadly relieve the common resistance of hypoxic tumors to anticancer therapy. Cancer Res; 76(13); 3744-55. ©2016 AACR.

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

    DOE PAGES

    Smith, Megan M.; Hao, Yue; Mason, Harris E.; ...

    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 featuresmore » 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.« less

  4. Erosion studies at Lake Pyhäjärvi catchment (SW Finland)

    NASA Astrophysics Data System (ADS)

    Kirkkala, Teija; Ventelä, Anne-Mari; Tarvainen, Marjo; Jolma, Ari

    2014-05-01

    Lake Säkylän Pyhäjärvi is a large and shallow lake located in the centre of an intensive agricultural area in southwest Finland and it suffering from eutrophication. The nutrient load to Pyhäjärvi comes from diffuse agricultural sources in the catchment. The dominant land cover in the catchment area (22%) is made by cultivated fields, the rest comprising forests, peat lands and built-up areas. The soils of the Pyhäjärvi catchment are erosion sensitive clay, silt, till and peat. The suspended solid and nutrient transport of the main rivers flowing to the lake has been monitored since 1980's. Most part (over 70 %) of phosphorus load is particulate and erosion originated. In recent years the climate change has changed runoff patterns. In winter, mean air temperature is about -2.1 ºC and the catchment is also normally covered by snow in winter. However, in recent years there have been many years with higher winter time temperature and precipitation. In winter the fields are usually without vegetation cover and rainfalls increase erosion. There are already clear long term changes observed in runoff patterns and suspended solid load patterns. The erosion risk invention has been made to Yläneenjoki catchment in order to allocate erosion preventing measures. Sedimentation ponds, wetlands, buffer zones and filters have been used to catch the suspended solids from runoff but these methods are inadequate. In order to efficiently reduce nutrient load to the lake, the focus of the restoration measures should be in the soil, especially erosion preventing. Therefore more deep understanding and studying of erosion processes are needed. Runoff and erosion amounts and patterns should be measured in different types of fields should be done and combined to GIS-analysis.

  5. How runoff begins (and ends): characterizing hydrologic response at the catchment scale

    USGS Publications Warehouse

    Mirus, Benjamin B.; Loague, Keith

    2013-01-01

    Improved understanding of the complex dynamics associated with spatially and temporally variable runoff response is needed to better understand the hydrology component of interdisciplinary problems. The objective of this study was to quantitatively characterize the environmental controls on runoff generation for the range of different streamflow-generation mechanisms illustrated in the classic Dunne diagram. The comprehensive physics-based model of coupled surface-subsurface flow, InHM, is employed in a heuristic mode. InHM has been employed previously to successfully simulate the observed hydrologic response at four diverse, well-characterized catchments, which provides the foundation for this study. The C3 and CB catchments are located within steep, forested terrain; the TW and R5 catchments are located in gently sloping rangeland. The InHM boundary-value problems for these four catchments provide the corner-stones for alternative simulation scenarios designed to address the question of how runoff begins (and ends). Simulated rainfall-runoff events are used to systematically explore the impact of soil-hydraulic properties and rainfall characteristics. This approach facilitates quantitative analysis of both integrated and distributed hydrologic responses at high-spatial and temporal resolution over the wide range of environmental conditions represented by the four catchments. The results from 140 unique simulation scenarios illustrate how rainfall intensity/depth, subsurface permeability contrasts, characteristic curve shapes, and topography provide important controls on the hydrologic-response dynamics. The processes by which runoff begins (and ends) are shown, in large part, to be defined by the relative rates of rainfall, infiltration, lateral flow convergence, and storage dynamics within the variably saturated soil layers.

  6. USE OF A LUMPED MODEL (MAGIC) TO BOUND THE ESTIMATION OF POTENTIAL FUTURE EFFECTS OF SULFUR AND NITROGEN DEPOSITION ON LAKE CHEMISTRY IN THE ADIRONDACK MOUNTAINS

    EPA Science Inventory

    Leaching of atmospherically deposited nitrogen from forested watersheds can acidify lakes and streams. Using a modified version of the Model of Acidification of Groundwater in Catchments, we made computer simulations of such effects for 36 lake catchments in the Adirondack Mount...

  7. Phosphorus and dissolved organic carbon export during peak flow periods in three small homogenous catchments in eastern Germany

    NASA Astrophysics Data System (ADS)

    Benning, R.; Schwärzel, K.; Feger, K. H.

    2012-04-01

    Regional climate change scenarios for Central Europe predict both an overall increase in temperature and alterations in annual precipitation regimes. For large parts of Central Europe, climate change is expected to result in an increase in winter precipitation and a decrease in summer precipitation. In addition, an increase in extreme conditions, such as heat waves, prolonged drought periods, and heavy rainfall events are predicted. This research examines the potential impacts of increased heavy rainfall events on matter export from small catchment areas, and how different vegetation cover and land management options effects these exports. In order to evaluate the export of matter from different land-use types in the Eastern Ore Mountains (Saxony, NE Germany, 50° 48'18.06" North, 13° 36'24.54" East), study sites were established in three small catchments with homogeneous land-use. These study areas are each sub-catchments of the Ammelsdorf catchment, which provides inflow to the Lehnmühle reservoir (a major water supply for the city of Dresden). Each sub catchment represents one of the three main land-use types in the catchment area of the reservoir: crops (winter oilseed rape, winter wheat), grasslands, and forests (primarily spruce). Since November 2009 the discharge from these sub catchments has been continuously measured and water quality was analyzed on a weekly basis. During peak flow events, discharge was collected using automatic water samplers, which allowed for high temporal resolution analysis of matter export during these periods to be made. During the 2010 and 2011 hydrological years, several heavy rainfall events occurred which have been evaluated. During a 110-hour long precipitation event (P = 170 mm) between 37 and 81 water samples per sub catchment were collected and analyzed. The resulting export of dissolved phosphorus (ortho-PO4-) and dissolved organic carbon (DOC) from the sub catchments during this event is provided in the results. In

  8. Before and after integrated catchment management in a headwater catchment: changes in water quality.

    PubMed

    Hughes, Andrew O; Quinn, John M

    2014-12-01

    Few studies have comprehensively measured the effect on water quality of catchment rehabilitation measures in comparison with baseline conditions. Here we have analyzed water clarity and nutrient concentrations and loads for a 13-year period in a headwater catchment within the western Waikato region, New Zealand. For the first 6 years, the entire catchment was used for hill-country cattle and sheep grazing. An integrated catchment management plan was implemented whereby cattle were excluded from riparian areas, the most degraded land was planted in Pinus radiata, channel banks were planted with poplar trees and the beef cattle enterprise was modified. The removal of cattle from riparian areas without additional riparian planting had a positive and rapid effect on stream water clarity. In contrast, the water clarity decreased in those sub-catchments where livestock was excluded but riparian areas were planted with trees and shrubs. We attribute the decrease in water clarity to a reduction in groundcover vegetation that armors stream banks against preparatory erosion processes. Increases in concentrations of forms of P and N were recorded. These increases were attributed to: (i) the reduction of instream nutrient uptake by macrophytes and periphyton due to increased riparian shading; (ii) uncontrolled growth of a nitrogen fixing weed (gorse) in some parts of the catchment, and (iii) the reduction in the nutrient attenuation capacity of seepage wetlands due to the decrease in their areal coverage in response to afforestation. Our findings highlight the complex nature of the water quality response to catchment rehabilitation measures.

  9. Before and After Integrated Catchment Management in a Headwater Catchment: Changes in Water Quality

    NASA Astrophysics Data System (ADS)

    Hughes, Andrew O.; Quinn, John M.

    2014-12-01

    Few studies have comprehensively measured the effect on water quality of catchment rehabilitation measures in comparison with baseline conditions. Here we have analyzed water clarity and nutrient concentrations and loads for a 13-year period in a headwater catchment within the western Waikato region, New Zealand. For the first 6 years, the entire catchment was used for hill-country cattle and sheep grazing. An integrated catchment management plan was implemented whereby cattle were excluded from riparian areas, the most degraded land was planted in Pinus radiata, channel banks were planted with poplar trees and the beef cattle enterprise was modified. The removal of cattle from riparian areas without additional riparian planting had a positive and rapid effect on stream water clarity. In contrast, the water clarity decreased in those sub-catchments where livestock was excluded but riparian areas were planted with trees and shrubs. We attribute the decrease in water clarity to a reduction in groundcover vegetation that armors stream banks against preparatory erosion processes. Increases in concentrations of forms of P and N were recorded. These increases were attributed to: (i) the reduction of instream nutrient uptake by macrophytes and periphyton due to increased riparian shading; (ii) uncontrolled growth of a nitrogen fixing weed (gorse) in some parts of the catchment, and (iii) the reduction in the nutrient attenuation capacity of seepage wetlands due to the decrease in their areal coverage in response to afforestation. Our findings highlight the complex nature of the water quality response to catchment rehabilitation measures.

  10. How old is upland catchment water?

    NASA Astrophysics Data System (ADS)

    Hofmann, Harald; Cartwright, Ian; Morgenstern, Uwe; Gilfedder, Benjamin

    2014-05-01

    Understanding the dynamics of water supply catchments is an essential part of water management. Upland catchments provide a continuous, reliable source of high quality water not only for some of the world's biggest cities, but also for agriculture and industry. Headwater streams control river flow in lowland agricultural basins as the majority of river discharge emerges from upland catchments. Many rivers are perennial and flow throughout the year, even during droughts. However, it is still unclear how reliable and continuous upland catchment water resources really are. Despite many efforts in upland catchment research, there is still little known about where the water is stored and how long it takes to travel through upper catchments. Resolving these questions is crucial to ensure that this resource is protected from changing land use and to estimate potential impacts from a changing climate. Previous research in this important area has been limited by existing measurement techniques. Knowledge to date has relied heavily on the use of variation in stable isotope signals to estimate the age and origin of water from upland catchments. The problem with relying on these measures is that as the water residence time increases, the variation in the stable isotope signal decreases. After a maximum period of four years, no variation can be detected This means that to date, the residence time in upland catchments is likely to have been vastly underestimated. Consequently, the proportion of water flow out of upland river catchments to the total river flow is also underestimated. Tritium (3H) combines directly with water molecules and enters the flow paths with the infiltrating water. Its half-life (12.32 years) makes it ideal to describe residence times in upper catchment reservoirs as it can theoretically measure water up to about 150 years old. The bomb pulse peak in the southern hemisphere was several orders of magnitude lower than in the northern hemisphere. Hence the

  11. Catchment scale multi-objective flood management

    NASA Astrophysics Data System (ADS)

    Rose, Steve; Worrall, Peter; Rosolova, Zdenka; Hammond, Gene

    2010-05-01

    Rural land management is known to affect both the generation and propagation of flooding at the local scale, but there is still a general lack of good evidence that this impact is still significant at the larger catchment scale given the complexity of physical interactions and climatic variability taking place at this level. The National Trust, in partnership with the Environment Agency, are managing an innovative project on the Holnicote Estate in south west England to demonstrate the benefits of using good rural land management practices to reduce flood risk at the both the catchment and sub-catchment scales. The Holnicote Estate is owned by the National Trust and comprises about 5,000 hectares of land, from the uplands of Exmoor to the sea, incorporating most of the catchments of the river Horner and Aller Water. There are nearly 100 houses across three villages that are at risk from flooding which could potentially benefit from changes in land management practices in the surrounding catchment providing a more sustainable flood attenuation function. In addition to the contribution being made to flood risk management there are a range of other ecosystems services that will be enhanced through these targeted land management changes. Alterations in land management will create new opportunities for wildlife and habitats and help to improve the local surface water quality. Such improvements will not only create additional wildlife resources locally but also serve the landscape response to climate change effects by creating and enhancing wildlife networks within the region. Land management changes will also restore and sustain landscape heritage resources and provide opportunities for amenity, recreation and tourism. The project delivery team is working with the National Trust from source to sea across the entire Holnicote Estate, to identify and subsequently implement suitable land management techniques to manage local flood risk within the catchments. These

  12. The application of time-lapse photography for the observation of snow processes in mountainous catchments

    NASA Astrophysics Data System (ADS)

    Garvelmann, J.; Pohl, S.; Weiler, M.

    2012-04-01

    For the forecast of snowmelt flood events in mountainous catchments it is very important to know the spatial distribution and temporal evolution of the snowcover. Topography and vegetation have the most important influence on the spatio-temporal variability of the snowcover. In order to accomplish a continuous observation of the quantity and the status of the snowcover, an extensive measurement network consisting of numerous standalone snow and meteorological sensors and time-lapse photography was established in three catchments in the Black Forest, a typical mid latitude medium elevation mountain range. Catchments with different topographic characteristic and areal extent were specifically chosen for this study. Within the catchments, a stratified sampling design was used to cover a wide range of altitudes and exposures. In order to investigate the influence of a vegetation cover on the snow processes beneath sensors and cameras have been installed under the forest canopy and on adjacent open field sites, respectively. In the presented study the application of spatially distributed time-lapse cameras for the observation of snow processes and snowcover properties at the catchment scale will be discussed. Image analysis software was applied to extract information about snowdepth, snow albedo and canopy interception from the digital images. A measurement scale with a black/white board was installed in the focus of every camera to allow a determination of the snowdepth at every camera location while the black/white board was used to provide a white balance for the albedo estimation. The albedo provides important information about the status of the snowcover and its temporal evolution is a crucial factor for the snowmelt energy balance. Furthermore the time-lapse images provided a continuous observation of the forest canopy allowing the estimation of the interception efficiency and the temporal evolution of the snow interception for different topographic situations

  13. Validation of Pacific Northwest hydrologic landscapes at the catchment scale

    EPA Science Inventory

    The interaction between the physical properties of a catchment (form) and climatic forcing of precipitation and energy control how water is partitioned, stored, and conveyed through a catchment (function). Hydrologic Landscapes (HLs) were previously developed across Oregon and de...

  14. Characterizing streamflow generation in Alpine catchments

    NASA Astrophysics Data System (ADS)

    Chiogna, Gabriele; Cano Paoli, Karina; Bellin, Alberto

    2016-04-01

    Developing effective hydrological models for streamflow generation in Alpine catchments is challenging due to the inherent complexity of the intertwined processes controlling water transfer from hillslopes to streams and along the river network. With water discharge as the sole observational variable it is impossible to differentiate between different streamflow sources, and modelling activity is often limited to simplified phenomenological rainfall-runoff models. This study focuses on quantifying streamflow sources at different temporal scales and the associated uncertainty by using natural tracer data (electrical conductivity, oxygen and hydrogen stable isotopes ratios) as observational variables supplementing streamflow measurements. We determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy and we separate contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. Furthermore, we identify a seasonal control on the effect of storm events. The catchment responded rapidly to precipitation events in early autumn, it was unaffected by precipitation events in early spring, while runoff generation was enhanced by snow melting in late autumn. Air temperature is identified as the main controlling parameter, in addition to precipitation. Two-component mixing analysis showed that the relative contribution of new water, which can contribute up to 75% of total streamflow, is very rapid. Only two hours time-lag was observed between the beginning of the precipitation event and the emergence of a significant contribution of new water. These results evidence the relevance of mixing between pre-event and event water in the Vermigliana catchment, and in similar high elevation Alpine catchments. This study provides new insights on the dynamics of streamflow generation in Alpine catchments and a

  15. Environmental isotope hydrology of salinized experimental catchments

    NASA Astrophysics Data System (ADS)

    Turner, J. V.; Arad, A.; Johnston, C. D.

    1987-10-01

    Deuterium, oxygen-18, tritium and chloride concentrations were used in three salinized experimental catchments to gain insight into the mechanism of solute concentration and flow processes in the saturated and unsaturated zones. The three experimental catchments were studied because of their location in different rainfall regions, their status with respect to clearing of native vegetation and with respect to secondary salinization. Two uncleared catchments have average annual rainfalls of approximately 820 and 1220 mm, respectively. The third cleared catchment has an annual rainfall of 650-750 mm. This catchment was in an advanced state of secondary salinization and displayed large areas of saline groundwater discharge with halite encrustation at the ground surface. The stable isotope compositions of the solution phase in solute bulge profiles in the unsaturated zone showed a close agreement with the amount-weighted mean isotopic composition of rainfall and only surficial evidence of isotopic enrichment due to evaporation. Evaporation from the soil surface plays a minor role as a mechanism of solute concentration in the unsaturated zone. The dominant process of solute concentration in the unsaturated zone was ion exclusion during uptake of water by tree roots which was evidently a solute but not isotope fractionating process. Tritium analyses of unsaturated zone water and grondwater indicated movement of recent recharge to 7-10 m depth at the low rainfall site but over the full depth of the 15 m unsaturated zone at the higher rainfall site. The variability in δ18O and δ2H values of groundwaters was used in association with chloride concentrations to provide information on mixing characteristics of groundwaters within the catchments.

  16. Impact of rainforest conversion on water yield, seasonal flow and floods in a tropical catchment in Central Sulawesi, Indonesia

    NASA Astrophysics Data System (ADS)

    Kleinhans, A.; Gerold, G.

    2003-04-01

    Smallholder agriculture is playing an important role in rainforest conversion in the humid tropics. After conversion by smallholders the created landscape is characterized by a patchwork of different land use types in ever smaller patches undergoing a gradual change from forest dominated patches via annual crops to perennial plantation interspersed by secondary forest, pasture and annual crops. Our mountainous research area along the rainforest margin area of the Lore Lindu National Park in Central Sulawesi, Indonesia shows in an exemplary manner this sequence of conversion with natural forest at the mountainous upland and perennial plantation at the lowland connected by a moving transition zone of annual crops and young plantation. There, we are investigating the hydrological responses to the gradual conversions on the hydrological behaviour of low flows and high flows in a small catchment area and the factors causing these changes. To fulfil the goal we use a modified catchment approach with three weirs including water level recorders along the river with each weir representative for one predominant land use type. This design allows to measure the influence of land use changes on the water fluxes with the undisturbed headwater catchment serving as a reference. Additionally the meteorological inputs are measured with two automatic weather stations and four automatic rain gauges. On plot scale 30 soil water content measurement plots have been installed and soil physical properties in the different land use types have been measured to validate the results on catchment scale. Since the measurements started in 2001 our first results show an increase in the yearly water yield in the recently logged transition zone in comparison to the natural forest. Especially during low flow conditions water yield from converted areas is higher in comparison to natural forest. Reasons can be found in the reduced evapotranspiration after removal of the natural forest canopy. Floods

  17. Picturing and modelling catchments by representative hillslopes

    NASA Astrophysics Data System (ADS)

    Loritz, Ralf; Hassler, Sibylle; Jackisch, Conrad; Zehe, Erwin

    2016-04-01

    Hydrological modelling studies often start with a qualitative sketch of the hydrological processes of a catchment. These so-called perceptual models are often pictured as hillslopes and are generalizations displaying only the dominant and relevant processes of a catchment or hillslope. The problem with these models is that they are prone to become too much predetermined by the designer's background and experience. Moreover it is difficult to know if that picture is correct and contains enough complexity to represent the system under study. Nevertheless, because of their qualitative form, perceptual models are easy to understand and can be an excellent tool for multidisciplinary exchange between researchers with different backgrounds, helping to identify the dominant structures and processes in a catchment. In our study we explore whether a perceptual model built upon an intensive field campaign may serve as a blueprint for setting up representative hillslopes in a hydrological model to reproduce the functioning of two distinctly different catchments. We use a physically-based 2D hillslope model which has proven capable to be driven by measured soil-hydrological parameters. A key asset of our approach is that the model structure itself remains a picture of the perceptual model, which is benchmarked against a) geo-physical images of the subsurface and b) observed dynamics of discharge, distributed state variables and fluxes (soil moisture, matric potential and sap flow). Within this approach we are able to set up two behavioral model structures which allow the simulation of the most important hydrological fluxes and state variables in good accordance with available observations within the 19.4 km2 large Colpach catchment and the 4.5 km2 large Wollefsbach catchment in Luxembourg without the necessity of calibration. This corroborates, contrary to the widespread opinion, that a) lower mesoscale catchments may be modelled by representative hillslopes and b) physically

  18. Identification of internal flow dynamics in two experimental catchments

    USGS Publications Warehouse

    Hansen, D.P.; Jakeman, A.J.; Kendall, C.; Weizu, G.

    1997-01-01

    Identification of the internal flow dynamics in catchments is difficult because of the lack of information in precipitation -stream discharge time series alone. Two experimental catchments, Hydrohill and Nandadish, near Nanjing in China, have been set up to monitor internal flows reaching the catchment stream at various depths, from the surface runoff to the bedrock. With analysis of the precipitation against these internal discharges, it is possible to quantify the time constants and volumes associated with various flowpaths in both catchments.

  19. Impacts of fire on forest age and runoff in mountain ash forests

    USGS Publications Warehouse

    Wood, S.A.; Beringer, J.; Hutley, L.B.; McGuire, A.D.; Van Dijk, A.; Kilinc, M.

    2008-01-01

    Runoff from mountain ash (Eucalyptus regnans F.Muell.) forested catchments has been shown to decline significantly in the few decades following fire - returning to pre-fire levels in the following centuries - owing to changes in ecosystem water use with stand age in a relationship known as Kuczera's model. We examined this relationship between catchment runoff and stand age by measuring whole-ecosystem exchanges of water using an eddy covariance system measuring forest evapotranspiration (ET) combined with sap-flow measurements of tree water use, with measurements made across a chronosequence of three sites (24, 80 and 296 years since fire). At the 296-year old site eddy covariance systems were installed above the E. regnans overstorey and above the distinct rainforest understorey. Contrary to predictions from the Kuczera curve, we found that measurements of whole-forest ET decreased by far less across stand age between 24 and 296 years. Although the overstorey tree water use declined by 1.8 mm day-1 with increasing forest age (an annual decrease of 657 mm) the understorey ET contributed between 1.2 and 1.5 mm day-1, 45% of the total ET (3 mm day-1) at the old growth forest. ?? CSIRO 2008.

  20. Impacts of forest age on water use in Mountain ash forests

    USGS Publications Warehouse

    Wood, Stephen A.; Beringer, Jason; Hutley, Lindsay B.; McGuire, A. David; Van Dijk, Albert; Kilinc, Musa

    2008-01-01

    Runoff from mountain ash (Eucalyptus regnans F.Muell.) forested catchments has been shown to decline significantly in the few decades following fire returning to pre-fire levels in the following centuries owing to changes in ecosystem water use with stand age in a relationship known as Kuczera's model. We examined this relationship between catchment runoff and stand age by measuring whole-ecosystem exchanges of water using an eddy covariance system measuring forest evapotranspiration (ET) combined with sap-flow measurements of tree water use, with measurements made across a chronosequence of three sites (24, 80 and 296 years since fire). At the 296-year old site eddy covariance systems were installed above the E. regnans overstorey and above the distinct rainforest understorey. Contrary to predictions from the Kuczera curve, we found that measurements of whole-forest ET decreased by far less across stand age between 24 and 296 years. Although the overstorey tree water use declined by 1.8mmday-1 with increasing forest age (an annual decrease of 657mm) the understorey ET contributed between 1.2 and 1.5mmday-1, 45% of the total ET (3mmday-1) at the old growth forest.

  1. Multivariate analysis of soil moisture and runoff dynamics for better understanding of catchment moisture state

    NASA Astrophysics Data System (ADS)

    Graeff, Thomas; Bronstert, Axel; Cunha Costa, Alexandre; Zehe, Erwin

    2010-05-01

    Soil moisture is a key state that controls runoff formation, infiltration and portioning of radiation into latent and sensible heat flux. The experimental characterisation of near surface soil moisture patterns and their controls on runoff formation is, however, still largely untapped. Using an intelligent sampling strategy of two TDR clusters installed in the head water of the Wilde Weißeritz catchment (Eastern Ore Mountains, Germany), we investigated how well "the catchment state" may be characterised by means of distributed soil moisture data observed at the field scale. A grassland site and a forested site both located on gentle slopes were instrumented with two Spatial TDR clusters (STDR) that consist of 39 and 32 coated TDR probes of 60 cm length. The interplay of soil moisture and runoff formation was interrogated using discharge data from three nested catchments: the Becherbach with a size of 2 km², the Rehefeld catchment (17 km²) and the superordinate Ammelsdorf catchment (49 km²). Multiple regression analysis and information theory including observations of groundwater levels, soil moisture and rainfall intensity were employed to predict stream flow. On the small scale we found a strong correlation between the average soil moisture and the runoff coefficients of rainfall-runoff events, which almost explains as much variability as the pre-event runoff. There was, furthermore, a strong correlation between surface soil moisture and subsurface wetness. With increasing catchment size, the explanatory power of soil moisture reduced, but it was still in a good accordance to the former results. Combining those results with a recession analysis of soil moisture and discharge we derived a first conceptual model of the dominant runoff mechanisms operating in these catchments, namely subsurface flow, but also by groundwater. The multivariate analysis indicated that the proposed sampling strategy of clustering TDR probes in typical functional units is a promising

  2. Complex Catchment Processes that Control Stream Nitrogen and Organic Matter Concentrations in a Northeastern USA Upland Catchment

    NASA Astrophysics Data System (ADS)

    Sebestyen, S. D.; Shanley, J. B.; Pellerin, B.; Saraceno, J.; Aiken, G. R.; Boyer, E. W.; Doctor, D. H.; Kendall, C.

    2009-05-01

    There is a need to understand the coupled biogeochemical and hydrological processes that control stream hydrochemistry in upland forested catchments. At watershed 9 (W-9) of the Sleepers River Research Watershed in the northeastern USA, we use high-frequency sampling, environmental tracers, end-member mixing analysis, and stream reach mass balances to understand dynamic factors affect forms and concentrations of nitrogen and organic matter in streamflow. We found that rates of stream nitrate processing changed during autumn baseflow and that up to 70% of nitrate inputs to a stream reach were retained. At the same time, the stream reach was a net source of the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) fractions of dissolved organic matter (DOM). The in-stream nitrate loss and DOM gains are examples of hot moments of biogeochemical transformations during autumn when deciduous litter fall increases DOM availability. As hydrological flowpaths changed during rainfall events, the sources and transformations of nitrate and DOM differed from baseflow. For example, during storm flow we measured direct inputs of unprocessed atmospheric nitrate to streams that were as large as 30% of the stream nitrate loading. At the same time, stream DOM composition shifted to reflect inputs of reactive organic matter from surficial upland soils. The transport of atmospheric nitrate and reactive DOM to streams underscores the importance of quantifying source variation during short-duration stormflow events. Building upon these findings we present a conceptual model of interacting ecosystem processes that control the flow of water and nutrients to streams in a temperate upland catchment.

  3. The most acidified Austrian lake in comparison to a neutralized mining lake

    PubMed Central

    Moser, Michael; Weisse, Thomas

    2011-01-01

    This study investigated two mining lakes located in the north of Lower Austria. These lakes arose 45 years ago when open cast lignite mining ceased. The lakes are separated by a 7-m wide dam. Due to the oxidation of pyrite, both lakes have been acidified and exhibit iron, sulphate, and heavy metal concentrations several orders of magnitude higher than in circumneutral lakes. The water column of both lakes is divided into two layers by a pronounced chemocline. The smaller mining lake (AML), with pH close to of 2.6, is the most acidic lake in Austria, whereas flooding with stream water and by drainage from the surrounding fields neutralized the adjacent larger pit lake. The goal of our study was to investigate the effect of flooding on its physical, chemical and biological properties, in comparison to the pristine AML. Even relative to other extremely acidic lakes, the flora and fauna in the AML was reduced and composed of only two flagellate, one ciliate, and one rotifer species. The simplified pelagic food web in the mixolimnion consisted of heterotrophic bacteria, the mixotrophic flagellates Chlamydomonas acidophila and Ochromonas sp., the ciliate Oxytricha sp., and the rotifer Cephalodella sp. The latter two are as yet undescribed new species. The heliozoan Actinophrys sp. that may act as top predator occurred only in low abundance. The euglenid Lepocinclis buetschlii formed a stable deep chlorophyll maximum (DCM) at 7 m depth. Highest cell numbers of L. buetschlii in the DCM exceeded 108 L−1. The neutralized mining lake harboured higher plankton diversity similar to that of natural circumneutral lakes. A peak of at least 16 different phytoplankton taxa was observed during summer. The zooplankton consisted of several copepod species, daphnids and other cladocerans, and at least six different rotifer species. Several fish species occurred in the neutralized lake. Although the effect of non-permanent flooding was largely sustainable, interannual fluctuations of

  4. The most acidified Austrian lake in comparison to a neutralized mining lake.

    PubMed

    Moser, Michael; Weisse, Thomas

    2011-12-01

    This study investigated two mining lakes located in the north of Lower Austria. These lakes arose 45 years ago when open cast lignite mining ceased. The lakes are separated by a 7-m wide dam. Due to the oxidation of pyrite, both lakes have been acidified and exhibit iron, sulphate, and heavy metal concentrations several orders of magnitude higher than in circumneutral lakes. The water column of both lakes is divided into two layers by a pronounced chemocline. The smaller mining lake (AML), with pH close to of 2.6, is the most acidic lake in Austria, whereas flooding with stream water and by drainage from the surrounding fields neutralized the adjacent larger pit lake. The goal of our study was to investigate the effect of flooding on its physical, chemical and biological properties, in comparison to the pristine AML. Even relative to other extremely acidic lakes, the flora and fauna in the AML was reduced and composed of only two flagellate, one ciliate, and one rotifer species. The simplified pelagic food web in the mixolimnion consisted of heterotrophic bacteria, the mixotrophic flagellates Chlamydomonas acidophila and Ochromonas sp., the ciliate Oxytricha sp., and the rotifer Cephalodella sp. The latter two are as yet undescribed new species. The heliozoan Actinophrys sp. that may act as top predator occurred only in low abundance. The euglenid Lepocinclis buetschlii formed a stable deep chlorophyll maximum (DCM) at 7 m depth. Highest cell numbers of L. buetschlii in the DCM exceeded 10(8) L(-1). The neutralized mining lake harboured higher plankton diversity similar to that of natural circumneutral lakes. A peak of at least 16 different phytoplankton taxa was observed during summer. The zooplankton consisted of several copepod species, daphnids and other cladocerans, and at least six different rotifer species. Several fish species occurred in the neutralized lake. Although the effect of non-permanent flooding was largely sustainable, interannual fluctuations

  5. Modifications of Carbonate Fracture Hydrodynamic Properties by CO 2 -Acidified Brine Flow

    SciTech Connect

    Deng, Hang; Ellis, Brian R.; Peters, Catherine A.; Fitts, Jeffrey P.; Crandall, Dustin; Bromhal, Grant S.

    2013-08-15

    Acidic reactive flow in fractures is relevant in subsurface activities such as CO{sub 2} geological storage and hydraulic fracturing. Understanding reaction-induced changes in fracture hydrodynamic properties is essential for predicting subsurface flows such as leakage, injectability, and fluid production. In this study, x-ray computed tomography scans of a fractured carbonate caprock were used to create three dimensional reconstructions of the fracture before and after reaction with CO{sub 2}-acidified brine (Ellis et al., 2011, Greenhouse Gases: Sci. Technol., 1:248-260). As expected, mechanical apertures were found to increase substantially, doubling and even tripling in some places. However, the surface geometry evolved in complex ways including ‘comb-tooth’ structures created from preferential dissolution of calcite in transverse sedimentary bands, and the creation of degraded zones, i.e. porous calcite-depleted areas on reacted fracture surfaces. These geometric alterations resulted in increased fracture roughness, as measured by surface Z{sub 2} parameters and fractal dimensions D{sub f}. Computational fluid dynamics (CFD) simulations were conducted to quantify the changes in hydraulic aperture, fracture transmissivity and permeability. The results show that the effective hydraulic apertures are smaller than the mechanical apertures, and the changes in hydraulic apertures are nonlinear. Overestimation of flow rate by a factor of two or more would be introduced if fracture hydrodynamic properties were based on mechanical apertures, or if hydraulic aperture is assumed to change proportionally with mechanical aperture. The differences can be attributed, in part, to the increase in roughness after reaction, and is likely affected by contiguous transverse sedimentary features. Hydraulic apertures estimated by the 1D statistical model and 2D local cubic law (LCL) model are consistently larger than those calculated from the CFD simulations. In addition, a novel

  6. Application of lime (CaCO3) to promote forest recovery from severe acidification increases potential for earthworm invasion

    USGS Publications Warehouse

    Homan, Caitlin; Beirer, Colin M; McCay, Timothy S; Lawrence, Gregory B.

    2016-01-01

    The application of lime (calcium carbonate) may be a cost-effective strategy to promote forest ecosystem recovery from acid impairment, under contemporary low levels of acidic deposition. However, liming acidified soils may create more suitable habitat for invasive earthworms that cause significant damage to forest floor communities and may disrupt ecosystem processes. We investigated the potential effects of liming in acidified soils where earthworms are rare in conjunction with a whole-ecosystem liming experiment in the chronically acidified forests of the western Adirondacks (USA). Using a microcosm experiment that replicated the whole-ecosystem treatment, we evaluated effects of soil liming on Lumbricus terrestris survivorship and biomass growth. We found that a moderate lime application (raising pH from 3.1 to 3.7) dramatically increased survival and biomass of L. terrestris, likely via increases in soil pH and associated reductions in inorganic aluminum, a known toxin. Very few L. terrestris individuals survived in unlimed soils, whereas earthworms in limed soils survived, grew, and rapidly consumed leaf litter. We supplemented this experiment with field surveys of extant earthworm communities along a gradient of soil pH in Adirondack hardwood forests, ranging from severely acidified (pH < 3) to well-buffered (pH > 5). In the field, no earthworms were observed where soil pH < 3.6. Abundance and species richness of earthworms was greatest in areas where soil pH > 4.4 and human dispersal vectors, including proximity to roads and public fishing access, were most prevalent. Overall our results suggest that moderate lime additions can be sufficient to increase earthworm invasion risk where dispersal vectors are present.

  7. Simultaneous occurrences of floods in mesoscale catchments

    NASA Astrophysics Data System (ADS)

    Bàrdossy, Andràs

    2016-04-01

    Floods in mesoscale catchments are often the result of intense precipitation of varying duration. The spatial extent of precipitation is linked to the extent of flooding. The simultaneous occurrence of floods in different medium size catchments is often the reason for large scale floods. The spatial behavior of extreme precipitation and discharge can be investigated using copulas and extreme indices. The relationship between intense precipitations measured at different locations depends on the large scale meteorological conditions. Depending on the geographic location and the dominating weather pattern certain catchments have frequent simultaneous extremes while others behave in a complementary fashion. The purpose of this work is to investigate the simultaneous and complementary occurrence of floods in catchments using copulas conditioned on atmospheric circulation patterns (CPs). Circulation patterns responsible for simultaneous floods are identified using areal precipitation and/or unusual discharge increases. Patterns are identified using a fuzzy rule based approach based on anomalies of the 700 hPa surfaces. The rules are formed by maximizing the explained variance under the assumption of simultaneous and complementary behavior. The conditional copulas are investigated for extreme behavior. Besides the traditional bivariate investigations higher dimensional dependences are investigated using an entropy based approach.

  8. Hydrological Modelling of Small Catchments Using Swat

    NASA Astrophysics Data System (ADS)

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

    The data from a 142ha catchment in Eastern England(Colworth, Bedfordshire)are be- ing used to investigate the performance of the USDA SWAT software for modelling hydrology of small catchments. Stream flow at the catchment outlet has been mon- itored 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. Three years of stream flow and climate data are available. Calibration and validation of stream flow was carried out with both runoff modelling options in the SWAT model (USDA curve number method and the Green and Ampt method). The Nash and Sutcliffe efficiencies for the calibration period were 66% and 63% respec- tively. The performance of SWAT was better in the validation period as a whole, with regard to timing of peaks, baseflow values and Nash and Sutcliffe efficiency. An ef- ficiency of 70% was obtained using the curve number method, which is comparable with the efficiencies obtainable with more complex models. Despite this performance, SWAT is under predicting stream flow peaks. A detailed investigation of important model components, has allowed us to identify some of the reasons for under predic- tion of stream flow peaks.

  9. Landscape types and pH control organic matter mediated mobilization of Al, Fe, U and La in boreal catchments

    NASA Astrophysics Data System (ADS)

    Köhler, Stephan J.; Lidman, Fredrik; Laudon, Hjalmar

    2014-06-01

    In this study we present data from a seven-year time series from 15 nested streams within a 68 km2 catchment, covering a pH gradient of almost three units. We demonstrate that the two landscape types, forest and wetlands, control the relative mobilization of Al and Fe in this boreal landscape. The La/U ratio is almost constant across the whole catchment despite large variations in pH, Al/Fe and TOC, whereas U and La mobilization increases with increasing contribution of deeper soils and groundwater further downstream. High Al/TOC ratios in the forested catchments suggest that Al originates from the underlying mineral soils, and low Al/TOC ratios derive from wetlands where Al is retained. We observe a competition effect on the binding to TOC between Al and La and also that the relationship between TOC, Al and La changes from the smaller (0.05-2 km2) catchments to larger (3-68 km2) downstream locations. As pH increase downstream, Al and Fe are gradually removed from the aqueous phase by precipitation of particulate gibbsite-like phases and ferrihydrite. This selective removal of Al and Fe from TOC binding sites results in higher La, and U concentrations downstream. Observed element patterns (U, La) and the range of upper continental crust normalized (La/Nd)UCC and (La/Yb)UCC in the near stream, riparian zone were very similar to the observed ratios across the whole catchment. The rising (La/Nd)UCC over (La/Yb)UCC may be due to a selective removal of REE binding to ferrihydrate in the riparian soil, the result of two distinctly different end-members but most probably not due to the in-stream precipitation of ferrihydrate or gibbsite-like phases.

  10. Freshwater transport forms of Na, Mg, and Ca in streams of adjacent headwater catchments composed of differing vegetation

    NASA Astrophysics Data System (ADS)

    Terajima, T.; Moriizumi, M.

    2012-04-01

    To understand the freshwater transport forms of major metals, concentrations of Na, Mg, Ca, Si, and fulvic acid-like materials (FAM) were measured in streams of headwater catchments with differing vegetation (coniferous and deciduous forests). The proportion of non-ionic forms (NIF) relative to total elements in the coniferous and deciduous catchments ranged from 0% to 40% and from 0% to 70%, respectively, in baseflows, and from 5% to 60% and from 20% to 60%, respectively, in stormflows. In the baseflows, NIF and total Si (T-Si) were highly correlated (r > 0.9) in both catchments. In contrast, in the stormflows, T-Si and FAM showed a good correlation (r > 0.8) in both catchments, implying that stormflow may have enhanced organic-inorganic binding. However, in the coniferous catchment, good correlations (r > 0.8) between NIF and T-Si or FAM were associated with only the rising limb of the hydrograph, whereas in the deciduous catchment, good correlations (r > 0.8) were associated with both the rising and falling limbs. These results indicate that: (1) under low-flow conditions, major metals may form binding with clay minerals and thus be transported as NIF, (2) storm events may enhance the binding of clay minerals with humic substances, (3) in the coniferous catchment, the complexation of NIF with the organic-inorganic binding and their transport in stormflows are associated with the rising limb of the storm hydrograph, whereas NIF transport during the falling limb may reflect the effect of other materials, and (4) in the deciduous catchment, NIF transport may occur mainly in association with organic-inorganic binding throughout a storm event. These findings show that active binding of Na, Mg, and Ca in freshwater environments with organic and inorganic substances, under the effect of differing vegetation on that binding, should be carefully examined in studies of chemical hydrology in headwater catchments. Key words: fulvic acid, major metal, complexation, humic

  11. Mean transit times in contrasting headwater catchments from southeast Australia determined using Tritium

    NASA Astrophysics Data System (ADS)

    Cartwright, Ian; Morgenstern, Uwe; Irvine, Dylan

    2016-04-01

    Headwater streams contribute a significant proportion of the total discharge of many river systems. However, despite their importance, the time taken for rainfall to pass through the catchment into the streams (the transit time) in headwater catchments is largely unknown as are the catchment characteristics (such as drainage density, topography, landuse, or geology) that determine variations in transit times. Because the peak in Tritium activities in rainfall produced by atmospheric nuclear tests in the1950's and 1960's (the "bomb-pulse") was several orders of magnitude lower in the southern hemisphere than in the northern hemisphere, Tritium activities of remnant bomb pulse water in the southern hemisphere have decayed below those of modern rainfall. This allows mean transit times to be estimated from single Tritium measurements. Here we use Tritium to estimate transit times of water contributing to perennial streams in the adjacent upper catchments of the Yarra and Latrobe Rivers (southeast Australia). Samples were collected at varying flow from six headwater tributary sites in the Latrobe catchment, which is largely forested and four tributaries in the Yarra catchment which has been extensively cleared for dryland agriculture. The lowest Tritium activities were recorded during summer baseflow conditions and are between 1.25 and 1.75 TU, these are significantly below the Tritium activity of local rainfall (~2.8 TU). Mean transit times calculated using an exponential-piston flow lumped parameter model are 21 to 47 years. Tritium activities during the recession periods following winter high flows are higher (1.54 to 2.1 TU), which may reflect either the dilution of a baseflow component with recent surface runoff or mobilisation of different stores of water with different residence times (e.g., from the soils or the regolith) from within the catchment. The variation of major ion concentrations with discharge suggests it is more likely that that different stores of

  12. Forest harvesting influence on slope erosion in Baikal Basin Mountains

    NASA Astrophysics Data System (ADS)

    Onuchin, A. A.; Borisov, A. N.; Burenina, T. A.

    2009-04-01

    Post-logging recovery of forest water protection and erosion prevention functions can occur different ways on slopes and in big river catchments. While erosion decreases several times during only three to five years after logging on slopes, as compared to its immediate post-logging rate, water silt load in big rivers can remain high for decades after forest logging in their catchments. Among other factors, this can be attributable to erosion of timber transportation roads and skidding trails, which become extremely eroded 10-15 years following forest logging. One should not underestimate a probable sediment load increase resulting from post-logging channel runoff changes. Disregarding this increase leads to contradictory conclusions about post-logging recovery of forest water protecting capability. Investigating this issue requires to clearly determine the type of the forest site of interest (a certain slope, an elementary or a complex catchments) and to consider the experience gained so far in estimating erosion rate changes depending on changing forest areas of continents. Therefore, hierarchical river catchments ranking should be recognized effective and useful for forest hydrology. This approach will allow systematizing the existing information and facilitating the development of fruitful analysis of water protection and erosion prevention functions of forest in areas of different ranks. This study used an approach that enabled a single-model description of the rate of soil erosion previously estimated by different models for areas of various ranks, from a micro slope to elementary catchments. An elementary catchments is defined as the smallest drainage area characterized by uniform surface, ground, and vegetation structures and having a single well-pronounced channel, with hydro network being practically absent. Using runoff slope length as the argument and introducing a dummy variable that describes specific investigation methodologies ensured high generality

  13. Inferring the effect of catchment complexity on mesoscale hydrologic response

    NASA Astrophysics Data System (ADS)

    FröHlich, Holger L.; Breuer, Lutz; Vaché, Kellie B.; Frede, Hans-Georg

    2008-09-01

    The effect of catchment complexity on hydrologic and hydrochemical catchment response was characterized in the mesoscale Dill catchment (692 km2), Germany. This analysis was developed using multivariate daily stream concentration and discharge data at the basin outlet, in connection with less frequently sampled catchment-wide end-member chemistries. The link between catchment-wide runoff sources and basin output was observed through a combination of concentration-discharge (C-Q) analysis and multivariate end-member projection. Subsurface stormflow, various groundwater and wastewater sources, as well as urban surface runoff emerged in catchment output chemistry. Despite the identification of multiple sources, several runoff sources observed within the catchment failed to display consistent links with the output chemistry. This failure to associate known source chemistry with outlet chemistry may have resulted from a lack of hydraulic connectivity between sources and basin outlet, from different arrival times of subbasin-scale runoff contributions, and also from an overlap of source chemistries that subsumed discrete runoff sources in catchment output. This combination of catchment heterogeneity and complexity simply suggests that the internal spatial organization of the catchment impeded the application of lumped mixing calculations at the 692 km2 outlet. Given these challenges, we suggest that in mesoscale catchment research, the potential effects of spatial organization should be included in any interpretation of highly integrated response signals, or when using those signals to evaluate numerical rainfall-runoff models.

  14. The heterogeneous kinetics of HOBr and HOCl on acidified sea salt and model aerosol at 40-90% relative humidity and ambient temperature.

    PubMed

    Pratte, Pascal; Rossi, Michel J

    2006-09-14

    The HOBr and HOCl uptake coefficient gamma on H(2)SO(4)-acidified submicron salt aerosol of known size distribution was measured in an atmospheric pressure laminar flow reactor. The interaction time of the trace gas with the aerosol was in the range 15 to 90 s and led to gamma values in the range 10(-4) to 10(-2). The acidity of the aerosol is essential in order to enable heterogeneous reactions of HOBr on NaCl, recrystallized sea salt (RSS) and natural sea salt (NSS) aerosols. Specifically, HOCl only reacts on acidified NSS aerosol with a gamma ranging from 0.4 x 10(-3) to 1.8 x 10(-3) at a relative humidity (rh) at 40 and 85%, respectively. Uptake experiments of HOBr on aqueous H(2)SO(4) as well as on H(2)SO(4)-acidified NaCl, RSS or NSS aerosol were performed for rh ranging from 40 to 93%. The gamma value of HOBr on acidified NSS reaches a maximum gamma = 1.9 x 10(-2) at rh = 76 +/- 1% and significantly decreases with increasing rh in contrast to acidified NaCl and RSS aerosols whose gamma values remain high at gamma = (1.0 +/- 0.2) x 10(-2) at rh >/= 80%. An explanation based on the formation of an organic coating on NSS aerosol with increasing rh is proposed.

  15. Post-Wildfire Impacts on Snow Accumulation and Melt: Hydrologic Implications for Headwater Catchments

    NASA Astrophysics Data System (ADS)

    Gleason, K. E.; Nolin, A. W.; Roth, T. R.

    2012-12-01

    disappeared several weeks earlier than in the unburned forest, mainly due to the substantial decrease in snow albedo. We discuss the hydrologic implications for headwater catchments in the West.

  16. Contribution of Soil Nitrogen Mineralization and Nitrification Pulses to Soil Nitrogen Availability and Nitrate Exports in a Mediterranean Catchment

    NASA Astrophysics Data System (ADS)

    Bernal, S.; Lupon, A.; Sabater, F.

    2015-12-01

    A good assessment of pulses of microbial nitrogen (N) supply is of paramount importance in helping understand the soil N cycle and catchment N exports in Mediterranean regions. Yet, the real contribution of N mineralization and nitrification pulses to soil N availability and catchment N exports remains unclear because most of the experiments have been performed on single forest ecosystem, while focusing on just few rainfall events. Over a year, we performed biweekly soil incubations to investigate patterns and controls of pulses of net N mineralization (NNM) and nitrification (NN) in three forests (riparian, evergreen oak and beech) coexisting within a Mediterranean headwater catchment. Further, we examined the influence of these pulses on soil N budgets and stream N loads. Within the catchment, riparian soils were hotspots of NNM and NN as they accounted for 30% of measured soil N supply, with median rates being multiple-fold higher than at the oak and beech forests. Pulses of NNM and NN generally occurred in spring immediately after large rainfall events (>20 mm). Moreover, high summer soil temperatures (>16ºC) promoted pulses of microbial activity at the riparian site. Although microbial pulses were restricted in time at all sites, they could contribute between 26-42% of the annual rates of NNM and NN. However, only NN pulses in the riparian site lead to disproportional increases in soil N availability and stream N loads, suggesting that these Mediterranean riparian soils could be a critical source of nitrate to the stream. Our study stresses that intensive monitoring is essential to capture hot moments of soil N processes, and thus to understand the relevance of microbial pulses on soil N biogeochemistry.

  17. Relating land use patterns to stream nutrient levels in red soil agricultural catchments in subtropical central China.

    PubMed

    Wang, Yi; Li, Yong; Liu, Xinliang; Liu, Feng; Li, Yuyuan; Song, Lifang; Li, Hang; Ma, Qiumei; Wu, Jinshui

    2014-09-01

    Land use has obvious influence on surface water quality; thus, it is important to understand the effects of land use patterns on surface water quality. This study explored the relationships between land use patterns and stream nutrient levels, including ammonium-N (NH4 (+)-N), nitrate-N (NO3 (-)-N), total N (TN), dissolved P (DP), and total P (TP) concentrations, in one forest and 12 agricultural catchments in subtropical central China. The results indicated that the TN concentrations ranged between 0.90 and 6.50 mg L(-1) and the TP concentrations ranged between 0.08 and 0.53 mg L(-1), showing that moderate nutrient pollution occurred in the catchments. The proportional areal coverages of forests, paddy fields, tea fields, residential areas, and water had distinct effects on stream nutrient levels. Except for the forest, all studied land use types had a potential to increase stream nutrient levels in the catchments. The land use pattern indices at the landscape level were significantly correlated to N nutrients but rarely correlated to P nutrients in stream water, whereas the influence of the land use pattern indices at the class level on stream water quality differentiated among the land use types and nutrient species. Multiple regression analysis suggested that land use pattern indices at the class level, including patch density (PD), largest patch index (LPI), mean shape index (SHMN), and mean Euclidian nearest neighbor distance (ENNMN), played an intrinsic role in influencing stream nutrient quality, and these four indices explained 35.08 % of the variability of stream nutrient levels in the catchments (p<0.001). Therefore, this research provides useful ideas and insights for land use planners and managers interested in controlling stream nutrient pollution in subtropical central China.

  18. Estimation of regional recharge in the HOBE catchment using data from a distributed soil moisture network

    NASA Astrophysics Data System (ADS)

    Andreasen, M.; Andreasen, L. A.; Bircher, S.; Sonnenborg, T.; Jensen, K. H.

    2012-12-01

    The regional variation of recharge of ground water is dependent on a larger number of variables and conditions and is therefore difficult to quantify. In this study we have estimated regional recharge using data from a distributed network of soil moisture stations within the HOBE catchment. The network has been designed in an arrangement of three clusters along a long-term precipitation gradient and the stations have been distributed according to respective fractions of classes combining the prevailing land use, top- and subsoil conditions. At each of the 30 stations water content has been measured at three depths (0-5cm, 20-25cm and 50-55cm) for the period 2009-2011 at a temporal resolution of 30 minutes. The 1D soil-plant-atmosphere system model DAISY has been applied to each of the field locations to simulate the water balance of the root zone and the associated components of evapotranspiration and recharge. The 30 models have been formulated and parameterized using specific information on local climate, soil texture, land use and management. Each model was calibrated to the measured soil water content from the distributed network using the PEST (Parameter ESTimation) software. The calibrated parameters were saturated hydraulic conductivity Ks and van Genuchten parameter n as they were found most sensitive. The 30 sets of results were averaged to represent the mean conditions of the catchment. An effective parameterization was also determined by calibration against mean soil moisture and compared to the results obtained by using effective parameters using various averaging methods. The regional variation in groundwater recharge, actual evapotranspiration and soil water content in the catchment was dependent on land use. The simulated results showed that the largest recharge was found at the agricultural sites (554 mm/yr) and the lowest at the forested sites (257 mm/yr). Correspondingly, the highest actual evapotranspiration was found at the forested sites (614

  19. Non-free ionic transport of sodium, magnesium, and calcium in streams of two adjacent headwater catchments with different vegetation types in Japan

    NASA Astrophysics Data System (ADS)

    Terajima, Tomomi; Moriizumi, Mihoko; Nakamura, Tomohiro

    2017-01-01

    Sodium (Na), magnesium (Mg), calcium (Ca) are usually believed to occur mostly as free ions in the fresh water and consequently little is known about their chemical species. To understand the importance of non-free ionic fractions (NIF) of major metals in freshwater streams, Na, Mg, Ca, silicon (Si), and fulvic acid-like materials (FAM) were measured in streams of mountainous adjacent headwater catchments dominated by different vegetation types (planted evergreen coniferous forest and natural deciduous broadleaf forest). During both no rainfall periods and rainstorms, the proportion of NIF relative to total elements was lower in the coniferous catchment than in the deciduous catchment, although it sometimes accounted for half or more of the total concentrations of Na, Mg, and Ca in both catchments. The solubility of metal compounds was higher than the measured maximum concentrations of Na+, Mg2+, and Ca2+ to the extent that inorganic bonding was hardly possible. During no rainfall periods when FAM was slightly produced into the streams, the fluxes of NIF and Si were highly correlated (r > 0.92, p < 0.0001, n = 30) in both catchments. During a small rainstorm, the flux of NIF correlated weakly with that of Si but did not correlate with that of FAM in both catchments. In contrast, during a heavy rainstorm, the flux of NIF correlated strongly (r ⩾ 0.83, p < 0.0001, n = 26) with that of FAM in the deciduous catchment where relatively deep soil water compared to near-surface water was the predominant component of stream water. However, during the heavy rainstorm in the coniferous catchment, only the flux of NIF originated in the quick-flow component (i.e., surface or near-surface water) in stream water (ΔNIF) correlated strongly (r ⩾ 0.81, p < 0.0001, n = 22) with that of FAM. These findings imply that heavy rainstorms may enhance the bonding of the major metals with humic substances mainly in the deciduous catchment; and also exhibit that, in the headwater

  20. Modelling seasonal and long-term patterns in stream dissolved organic carbon concentration in mire and forest dominated landscape elements at Svartberget, Sweden using INCA-C

    NASA Astrophysics Data System (ADS)

    Futter, M.; Koehler, S. J.; Bishop, K. H.

    2009-04-01

    We present an application of the INCA-C (Integrated Catchments model for Carbon) to the Svartberget catchment in central Sweden. The INCA-C model is a catchment-scale, semi-distributed, process-based model of dissolved organic carbon (DOC) that has been used previously to simulate intra- and inter-annual patterns in surface water DOC concentration and flux in boreal and temperate forested catchments (Futter et al. 2007). The 50 ha Svartberget catchment provides an ideal location for evaluating the performance of INCA-C as it contains two mire and upland landscape elements, where the output from each element has been monitored separately for a decade. Previous work has shown that these two landscape elements have markedly different intra-annual patterns of DOC concentration and export as well as the importance of the riparian zone in controlling surface water DOC concentration from the forested sub-catchment (Köhler et al. 2008). The 19 ha mire sub-catchment is dominated by bog communities with Scots pine in the upland areas. The 13 ha forested sub-catchment stream joins the main stem of the stream just above the confluence. It is dominated by Scots pine and Norway spruce. A third sub-catchment between the mire and the catchment outflow has a similar vegetation cover to that of the forested sub-catchment. INCA is designed to model different landscape elements, and combine them to simulate downstream locations. Like most complex, process-based models, however, INCA-C is over-determined. Insufficient data are available to constrain all processes and pool-sizes. As a result, similar in-stream DOC concentrations may be obtained by varying either aquatic or terrestrial rate parameters. The Svartberget catchment provides an opportunity to constrain the model parameter space for the entire catchment as there is information for the two major constituent elements, forest and mire. Additionally soil solution data from the riparian zone in the forest area together with a

  1. Photosynthetic kinetics determine the outcome of competition for dissolved inorganic carbon by freshwater microalgae: implications for acidified lakes.

    PubMed

    Williams, T G; Turpin, D H

    1987-09-01

    Photosynthetic kinetics with respect to dissolved inorganic carbon were used to predict the outcome of competition for DIC between the green alga Selenastrum minutum and the cyanobacterium Synechococcus leopoliensis at pH 6.2, 7.5, and 10. Based on measured values of the maximum rate of photosynthesis, the half-saturation value of photosynthesis with respect to DIC (K 1(2/DIC) ), and the DIC compensation point, it was predicted that S. leopoliensis would lower the steady-state DIC concentration below the DIC compensation point of S. minutum. This should result in competitive displacement of the green alga at a rate equivalent to the chemostat dilution rate. This prediction was validated by carrying out competition experiments over the range of pH. These results suggest that the low levels of DIC in air-equilibrated acidified lakes may be an important rate-limiting resource and hence affect phytoplankton community structure. Furthermore, the low levels of DIC in these systems may be below the DIC compensation point for some species, thereby precluding their growth at acid pH solely as a function of DIC limitation. The potential importance of DIC in shaping phytoplankton community structure in acidified systems is discussed.

  2. Assessment of the relationship among acidifying depositions, surface water acidification, and fish populations in North America. Volume 1. Final report

    SciTech Connect

    Marcus, M.D.; Parkhurst, B.R.; Payne, F.E.

    1983-06-01

    This report assesses the scientific understanding about relationships between acidic depositions and freshwater aquatic resources. Selected surface waters in eastern North America are becoming acidified and fish populations are being eliminated. The actual extent of these resources threatened by acidification is now known. Mostly circumstantial evidence has been compiled to suggest that long-range atmospheric transport of acidifying compounds is causing surface-water acidification in North America. Certainly, atmospheric emissions from point sources can impact localized areas. However, some data indicate that atmospheric inputs of acids from long-range transport may add little to the natural flux of acids within ecosystems. The degree of influence that atmosphere depositions can have in accelerating natural acidification rates is unknown for most potentially sensitive surface waters. Fish losses appear to result from (1) long-term accumulations of acids and metals reaching chronically toxic concentrations; and (2) short-term, episodic events causing acutely toxic acid and metal concentrations. Some impacts may be successfully mitigated through several methods. Additional research is needed to (1) identify causes of surface-water acidification; (2) develop innovative mitigation measures; (3) define mechanisms of fish loss; and (4) establish the extent of aquatic resources at risk.

  3. An Eco-hydrologic Assessment of Small Experimental Catchments with Various Land Uses within the Panama Canal Watershed: Agua Salud Project

    NASA Astrophysics Data System (ADS)

    Crouch, T. D.; Ogden, F. L.; Stallard, R. F.; Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project

    2010-12-01

    Hydrological processes in the humid tropics are poorly understood and an important topic when it comes to water management in the seasonal tropics. The Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project, seeks to understand these processes and quantify the long-term effects of different land cover and uses across the Panama Canal Watershed. One of the project’s main objectives is to understand how reforestation effects seasonal stream flows. To meet this objective, a baseline characterization of hydrology on the small catchment scale is being assessed across different land uses typical in rural Panama. The small experimental catchments are found within Panama’s protected Soberania National Park and the adjacent headwaters of the Agua Salud and Mendoza Rivers, all of which are part of the greater Panama Canal Watershed. The land uses being monitored include a variety of control catchments as well as treated pasture sites. The catchments used for this study include a mature old regrowth forest, a 50% deforested or mosaic regrowth site, an active pasture and a monoculture invasive grass site (saccharum spontaneum) as experimental controls and two treated catchments that were recently abandoned pastures converted to teak and native species timber plantations. Installed instrumentation includes a network of rain gauges, v-notched weirs, atmometers, an eddy covariance system and an assortment of meteorological and automated geochemical sampling systems. Spatial, rainfall, runoff and ET data across these six geologically and topographically similar catchments are available from 2009 and 2010. Classic water balance and paired catchment techniques were used to compare the catchments on an annual, seasonal, and event basis. This study sets the stage for hydrologic modeling and for better understanding the effects of vegetation and land-use history on rainfall-runoff processes for the Agua Salud Project and Panama Canal

  4. Characterizing hot spots throughout the catchment

    NASA Astrophysics Data System (ADS)

    Welti, N.; Lockington, D.; Jakeman, T.; Hunt, R.

    2012-04-01

    Few catchments in the world are left truly undisturbed. Rather, they are under anthropogenic stress for a variety of reasons ranging from climate forcing to meeting the basic water allocation needs of the population. Reduction in the number of inundation areas has significantly decreased the nutrient and organic matter retention capacity along the river corridor, with major consequences for the both the riverine and coastal ecosystems. Cumulative stress may build up to a "tipping point" which can cause a change or set of changes which could occur non-linearly. In order to mitigate the environmental stress on these ecosystems, management plans are created to balance the needs of the dependent populations and those of ecology. While these catchment-wide plans aim to improve the ecological function of aquatic areas over the large scale, this sledge-hammer approach ignores the inherent heterogeneity in the catchment. Societal (and policy) decisions involve more than abiotic quantification of water storage and flow. A more encompassing ecohydrological view facilitates a more rounded policy framework that has flexibility to accommodate multiple social drivers, and one that can accommodate an "ecosystem improvement" rather than single species improvement. Not every spot in the landscape is equally valuable for specific societal values. Areas of high activity may provide the resilience capacity necessary to prevent catastrophic changes. In times of ecological instability, ecosystem resilience is of paramount importance in maintaining essential ecosystem services. Hot spots of biogeochemical cycling will occur where unique situations arise, such as areas of surface and groundwater interaction, creating spots of localized, high activity. In order to understand the systems' potential to support various habitat niches in the large scale, the identification of specific hot spots or hot moments is necessary. A basal understanding of the concurrent biogeochemical cycles enables

  5. Groundwater Head Control of Catchment Nitrate Export

    NASA Astrophysics Data System (ADS)

    Musolff, A.; Schmidt, C.; Rode, M.; Fleckenstein, J. H.

    2014-12-01

    Elevated nutrient fluxes from agricultural catchments affect downstream water resources. A method to assess nutrient fluxes is the evaluation of the export regime. The export regime classifies the relation between concentration and discharge and integrates mobilization as well as retention processes. Solutes can be exported chemostatically (variance of concentration << variance of discharge) or chemodynamically (variance of concentration ≥ variance of discharge). Starting point of this study is the evaluation of export regimes of nitrate in a series of neighboring sub-catchments of the Central German River Bode catchment. We found an accretion pattern of nitrate with increasing concentration when discharge is increasing and thus a chemodynamic export regime. Here we follow a nested approach and have a closer look at the controls of nitrate export in the small (1.4 km2) headwater catchment of the Sauerbach stream. The Sauerbach catchment is dominated by agricultural land use and is characterized by tile drains. We hypothesize that discharge as well as nitrate export is controlled by the groundwater head variability over time. To that end we follow a joint data analysis of discharge, groundwater heads and nitrate concentrations in groundwater, tile drains and surface water. At the gauging station the nitrate export is chemodynamic exhibiting the typical accretion pattern also found at the larger scale. Our data analysis shows that nitrate export regime is in two ways controlled by the depth to groundwater and the groundwater head variability: Discharge increases with increasing groundwater heads due to the activation of tile drains. On the other hand, depth to groundwater and passage through the unsaturated zone is the major control of aquifer nitrate concentration. At wells with larger depth to groundwater nitrate concentrations are significantly lower than at more shallow wells indicating retention processes in the unsaturated zone. Therefore the concentration in

  6. Linking Soil Moisture, Micro-climate, and Transpiration in a Headwater Catchment

    NASA Astrophysics Data System (ADS)

    Barnard, H. R.; Brooks, J.; Kayler, Z.; Sulzman, E. W.; Phillips, C. L.; McDonnell, J. J.; Bond, B. J.

    2007-12-01

    Evapotranspiration is a major determinant of streamflow in forested basins. However, the role topography plays in forest water relations is poorly understood. To date, many hydrological models use only a single value for transpiration across a catchment. Quantifying the variation in forest water use with regards to slope position is central to understanding controls on water quantity and quality in hydro-ecological models and is critical to predicting the hydrologic impacts of various forestry operations. We measured transpiration, soil moisture, and foliar pre-dawn water potential in 4 plots across a ridge to ridge transect throughout the summers of 2005 and 2006 in a headwater catchment in western Oregon. Additionally, we measured deuterium and 18O of xylem water and soil water to track changes in the depth of transpiration source water throughout the summers. From May through October 2006, daily average transpiration in upslope plots was approximately 40% greater than that of valley bottom plots (1.0 mm day-1 vs. 0.6 mm day-1, respectively). Minimum pre-dawn water potential values ranged from -0.8 to -1.3 MPA in late August with north-facing plots having the lowest values. Stable isotope data indicates that transpiration rates remained higher longer in the growing season in plots where trees were able to access water deeper in the soil profile. Preliminary data suggest that topographic gradients influencing soil depth, soil moisture retention, and micro-climate result in large variation in forest water use over very small distances.

  7. Chapter 16Tracing Nitrogen Sources and Cycling in Catchments

    USGS Publications Warehouse

    Kendall, Carol

    1998-01-01

    This chapter focuses on the uses of isotopes to understand water chemistry.I Isotopic compositions generally cannot be interpreted successfully in the absence of other chemical and hydrologic data. The chapter focusses on uses of isotopes in tracing sources and cycling of nitrogen in the water-component of forested catchment, and on dissolved nitrate in shallow waters, nutrient uptake studies in agricultural areas, large-scale tracer experiments, groundwater contamination studies, food-web investigations, and uses of compound-specific stable isotope techniques. Shallow waters moving along a flowpath through a relatively uniform material and reacting with minerals probably do not achieve equilibrium but gradually approach some steady-state composition. The chapter also discusses the use of isotopic techniques to assess impacts of changes in land-management practices and land use on water quality. The analysis of individual molecular components for isotopic composition has much potential as a method for tracing the source, biogeochemistry, and degradation of organic liquids and gases because different materials have characteristic isotope spectrums or biomarkers.

  8. Manganese biogeochemistry in a central Czech Republic catchment

    USGS Publications Warehouse

    Navratil, T.; Shanley, J.B.; Skrivan, P.; Kram, P.; Mihaljevic, M.; Drahota, P.

    2007-01-01

    Mn biogeochemistry was studied from 1994 to 2003 in a small forested catchment in the central Czech Republic using the watershed mass balance approach together with measurements of internal stores and fluxes. Mn inputs in bulk deposition were relatively constant during a period of sharply decreasing acidic deposition, suggesting that the Mn source was terrestrial, and not from fossil fuel combustion. Mn inputs in bulk deposition and Mn supplied by weathering each averaged 13 mg m-2 year-1 (26 mg m -2 year-1 total input), whereas Mn export in streamwater and groundwater averaged 43 mg m-2 year-1. Thus an additional Mn source is needed to account for 17 mg m-2 year -1. Internal fluxes and pools of Mn were significantly greater than annual inputs and outputs. Throughfall Mn flux was 70 mg m-2 year-1, litterfall Mn flux was 103 mg m-2 year -1, and Mn net uptake by vegetation was 62 mg m-2 year-1. Large pools of labile or potentially labile Mn were present in biomass and surficial soil horizons. Small leakages from these large pools likely supply the additional Mn needed to close the watershed mass balance. This leakage may reflect an adjustment of the ecosystem to recent changes in atmospheric acidity. ?? 2007 Springer Science+Business Media B.V.

  9. Impact of catchment geophysical characteristics and climate on the regional variability of dissolved organic carbon (DOC) in surface water.

    PubMed

    Cool, Geneviève; Lebel, Alexandre; Sadiq, Rehan; Rodriguez, Manuel J

    2014-08-15

    Dissolved organic carbon (DOC) is a recognized indicator of natural organic matter (NOM) in surface waters. The aim of this paper is twofold: to evaluate the impact of geophysical characteristics, climate and ecological zones on DOC concentrations in surface waters and, to develop a statistical model to estimate the regional variability of these concentrations. In this study, multilevel statistical analysis was used to achieve three specific objectives: (1) evaluate the influence of climate and geophysical characteristics on DOC concentrations in surface waters; (2) compare the influence of geophysical characteristics and ecological zones on DOC concentrations in surface waters; and (3) develop a model to estimate the most accurate DOC concentrations in surface waters. The case study involved 115 catchments from surface waters in the Province of Quebec, Canada. Results showed that mean temperatures recorded 60 days prior to sampling, total precipitation 10 days prior to sampling and percentages of wetlands, coniferous forests and mixed forests have a significant positive influence on DOC concentrations in surface waters. The catchment mean slope had a significant negative influence on DOC concentrations in surface waters. Water type (lake or river) and deciduous forest variables were not significant. The ecological zones had a significant influence on DOC concentrations. However, geophysical characteristics (wetlands, forests and slope) estimated DOC concentrations more accurately. A model describing the variability of DOC concentrations was developed and can be used, in future research, for estimating DBPs in drinking water as well evaluating the impact of climate change on the quality of surface waters and drinking water.

  10. Formation and evolution of soils from an acidified watershed: Plastic Lake, Ontario, Canada

    SciTech Connect

    Kirkwood, D.E.; Nesbitt, H.W. )

    1991-05-01

    The Plastic Lake watershed contains podzols developed on glacial tills deposited 12,000 years ago. Present-day, cationic fluxes from the soils are greater by a factor of 2 than long-term fluxes averaged over the age of the tills. The high rates of present-day chemical weathering may be a result of increased input of anthropogenic acids into the Plastic Lake watershed. Time-averaged proportions of cations leached from the soils are strikingly different from the proportions of cations now being leached, indicating that the character of chemical weathering has changed over time. Weathering was and is dominated by mineral dissolution, but cation exchange has become increasingly important as the soils have matured. Bulk composition analyses of soil profiles demonstrate that feldspars of the AE horizon release base cations (Na, K, Ca) and Al to solution in near-stoichiometric proportions, just as is observed experimentally for feldspar dissolution in acidic solutions. Surface area-normalized, time-averaged, dissolution rates of primary minerals of Plastic Lake soils are significantly greater than present-day rates measured for mature soil profiles. Time-averaged concentrations of elements removed from the soil, recast into essential mineralogy, indicate that vermiculite weathers most rapidly, followed closely by plagioclase. K-feldspar weathers less rapidly than plagioclase but more rapidly than quartz or hornblende. The combination of high abundance and dissolution rate results in large amounts of quartz being dissolved from the soils of Plastic Lake; it may also contribute significantly to total elemental fluxes from other catchments.

  11. Holding Water in the Landscape; striking a balance between food production and healthy catchment function

    NASA Astrophysics Data System (ADS)

    Quinn, Paul; Wilkinson, Mark; Stutter, Marc; Adams, Russell

    2015-04-01

    Here it is proposed that ~5 % of the rural landscape could be modified to hold water during storm events. Hence ~95% of land remains for food production, commercial forestry and amenity. This is a catchment scale commitment to sustainably reducing flood and drought risk, improving water quality, biodiversity and thereby climate proofing our catchments. The farmed landscape has intensified and as a result, runoff rates are no longer in balance with the catchment needs, which in turn contributes to floods, droughts and water pollution problems. The loss of infiltration rates, soil water holding capacity and the increase in ditches and drains through intense farming has resulted in a reduction of the overall water holding capacity of the landscape, therefore deeper soil and aquifer recharge rates are lower. However, adequate raw water supply and food production is also vital. Here we consider how ~5% of productive land could be used to physically hold water during and after storms. This is a simple philosophy for water stewardship that could be delivered by farmers and land managers themselves. In this poster we consider a 'treatment train' of mitigation in headwaters by the construction of:- Rural SuDs - by creating swales, bunds and grassy filters; Buffer Strips - (designed to hold water); The Ditch of The Future - by creating the prime location for holding water and recovering lost top soil and finally the better use of Small Headwater Floodplains - by storing flood water, creating wetlands, planting new forest, installing woody debris and new habitats. We present examples of where and how these measures have been installed and show the cost-effectiveness of temporarily holding storm runoff in several case study catchments taken from the UK.

  12. First-order catchment mass balance during the wet season in the Panama Canal Watershed

    NASA Astrophysics Data System (ADS)

    Niedzialek, Justin M.; Ogden, Fred L.

    2012-09-01

    SummaryTropical hydrology is poorly understood for a number of reasons. Intense biological activity in the tropics introduces complexities to the hydrologic process. Bioturbation, rapid rates of decay, and intensive insect activity all tend to promote rapid flow paths in the upper soil. Aggressive weathering leads to clays depleted of light cations and deep soil profiles. Processes in the seasonal tropics are further complicated by seasonal transitions, and very large changes in catchment storage between seasons. Beginning in 2005, we installed a suite of hydrologic sensors in a 16.7 ha first-order catchment in the Panama Canal Watershed to observe hydrologic variables and identify the dominant streamflow generation processes. The site is located near the village of Gamboa, which is located on the east bank of the Panama Canal at the confluence of Lake Gatun and the Chagres River. The study catchment is located on the north side of a ridge off the eastern flank of a 230 m tall hill known as Cerro Pelado, and is covered by 70-120 year old re-growth triple-canopy forest. Measurements included: rainfall above the canopy, throughfall, stemflow, evapotranspiration, shallow groundwater levels and streamflow. Deep groundwater storage was not measured. This paper describes measurements made, data collected, and the worth of those data in estimating the mass balance closure of a first-order catchment during the wet season. We compare measurements of the different components of the water cycle with observations from other published studies from the tropics. Data analysis results indicate water balance closure errors of approximately 8%.

  13. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes.

    PubMed

    Eagles-Smith, Collin A; Herring, Garth; Johnson, Branden; Graw, Rick

    2016-05-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  14. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

    USGS Publications Warehouse

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2016-01-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  15. Reach-scale geomorphic differences between headwater streams draining mountaintop mined and unmined catchments

    NASA Astrophysics Data System (ADS)

    Jaeger, Kristin L.

    2015-05-01

    Mountaintop surface mining (MTM) is a controversial coal extraction method commonly practiced in the central and southern Appalachian Mountains, USA, that drastically reengineers previously steep, forested landscapes and alters sediment and water delivery processes to and along headwater channels draining mined areas. Although sediment delivery and hydrologic response from MTM operations remain highly variable and poorly resolved, the inherent close coupling between hillslopes and headwater channels is expected to result in geomorphic differences in stream channels draining MTM landscapes relative to unmined landscapes. Dedicated geomorphic studies are severely lacking in comparison to extensive research on water quality impacts of MTM. This study reports moderate geomorphic differences between headwater (catchment area <~ 6 km2) stream channels draining MTM and unmined catchments in tributaries of the Mud River in southern West Virginia. Univariate and multivariate analyses indicate that MTM streams are characterized by deeper maximum channel depths, smaller width-to-depth ratios, increased bedrock exposure along the streambed, and increased frequency of very fine silt and sand deposition relative to channels draining unmined catchments. Geomorphic differences are most pronounced for streams draining the smallest catchment areas (< 3.5 km2). Collectively, geomorphic differences provide evidence for relatively rapid channel adjustment of accelerated bedrock incision attributed to potential increased hydraulic driving forces and altered sediment regimes in MTM channels, notably sustained delivery of very fine sediment and potentially reduced coarse sediment delivery. More rapid delivery and transfer of water in addition to excess delivery of very fine sediments to and through headwater channels will have consequences to flooding and water quality in the short term and landscape evolution processes over longer time scales. Given the extent of MTM operations in this

  16. Adaptive forest management for drinking water protection under climate change

    NASA Astrophysics Data System (ADS)

    Koeck, R.; Hochbichler, E.

    2012-04-01

    Drinking water resources drawn from forested catchment areas are prominent for providing water supply on our planet. Despite the fact that source waters stemming from forested watersheds have generally lower water quality problems than those stemming from agriculturally used watersheds, it has to be guaranteed that the forest stands meet high standards regarding their water protection functionality. For fulfilling these, forest management concepts have to be applied, which are adaptive regarding the specific forest site conditions and also regarding climate change scenarios. In the past century forest management in the alpine area of Austria was mainly based on the cultivation of Norway spruce, by the way neglecting specific forest site conditions, what caused in many cases highly vulnerable mono-species forest stands. The GIS based forest hydrotope model (FoHyM) provides a framework for forest management, which defines the most crucial parameters in a spatial explicit form. FoHyM stratifies the spacious drinking water protection catchments into forest hydrotopes, being operational units for forest management. The primary information layer of FoHyM is the potential natural forest community, which reflects the specific forest site conditions regarding geology, soil types, elevation above sea level, exposition and inclination adequately and hence defines the specific forest hydrotopes. For each forest hydrotope, the adequate tree species composition and forest stand structure for drinking water protection functionality was deduced, based on the plant-sociological information base provided by FoHyM. The most important overall purpose for the related elaboration of adaptive forest management concepts and measures was the improvement of forest stand stability, which can be seen as the crucial parameter for drinking water protection. Only stable forest stands can protect the fragile soil and humus layers and hence prevent erosion process which could endanger the water

  17. A scalable chemical route to soluble acidified graphitic carbon nitride: an ideal precursor for isolated ultrathin g-C3N4 nanosheets

    NASA Astrophysics Data System (ADS)

    Du, Xiaorui; Zou, Guojun; Wang, Zhonghao; Wang, Xiaolai

    2015-05-01

    We propose an efficient method to synthesize large-scale soluble acidified graphitic carbon nitride (g-C3N4). The as-prepared material exhibits the characteristics of a poly-ammonium salt and is soluble in several solvents with good dissolution-recrystallization reversible equilibrium. The pH value- and temperature-dependent solubility of the acidified g-C3N4 facilitates its separation and purification. After dissolution, acidified g-C3N4 forms isolated ultrathin nanosheets, making it an ideal precursor for large quantities of g-C3N4 nanosheets. This study raises the possibility of liquid assembly for g-C3N4 nanosheets based composite materials, expanding the functionalization and application of g-C3N4.We propose an efficient method to synthesize large-scale soluble acidified graphitic carbon nitride (g-C3N4). The as-prepared material exhibits the characteristics of a poly-ammonium salt and is soluble in several solvents with good dissolution-recrystallization reversible equilibrium. The pH value- and temperature-dependent solubility of the acidified g-C3N4 facilitates its separation and purification. After dissolution, acidified g-C3N4 forms isolated ultrathin nanosheets, making it an ideal precursor for large quantities of g-C3N4 nanosheets. This study raises the possibility of liquid assembly for g-C3N4 nanosheets based composite materials, expanding the functionalization and application of g-C3N4. Electronic supplementary information (ESI) available: Experimental details, supporting information for XRD and XPS analysis, FT-IR and UV-vis spectra of the recovered g-C3N4, EIS Nyquist plots, solubility experiments and results, TEM and AFM images of g-C3N4 nanosheets, and photographs and TEM images of Pt@CNS. See DOI: 10.1039/c5nr00665a

  18. The ground beetle fauna (Coleoptera: Carabidae) of Kenyir water catchment, Terengganu, Peninsular Malaysia.

    PubMed

    Abdullah, Fauziah; Sina, Ibnu; Fauzee, Fatmahjihan

    2008-11-01

    An assemblage of beetle specimens from family Carabidae (ground beetles) was carried out at Kenyir water catchment as an indicator to measure disturbance. The sampl