Spatial variability in the response of surface-water extent to climate extremes across the Prairie Pothole Region and adjacent Northern Prairie, United States

NASA Astrophysics Data System (ADS)

Vanderhoof, M.; Lane, C.; McManus, M.; Alexander, L. C.; Christensen, J.

2017-12-01

Surface-water extent, duration and movement will depend not only on climatic inputs but also the relative importance of different hydrologic pathways (e.g., surface storage, infiltration, evapotranspiration, stream outflows). We mapped surface-water extent from historic drought years to historic wet years spanning 1985 - 2015 across eleven Landsat path/rows representing the Prairie Pothole Region (PPR) and adjacent Northern Prairie of the United States. The PPR not only experienced a greater surface water extent under median conditions (2.6 times more) relative to the adjacent Northern Prairie, but showed a greater difference between drought and deluge conditions as well (range averaged 8.5 ha surface water km-2 relative to 2.5 ha surface water km-2 for the PPR and Northern Prairie, respectively). To explain the spatial variability in the amount of surface water expansion and contraction we used a two-stage modeling approach. First, surface-water extent was regressed on accumulated water availability (precipitation minus potential evapotranspiration). The slope of surface-water extent to climate inputs (per watershed) was our dependent variable in the second stage. That slope was regressed against independent variables representing hydrology-related landscape characteristics (e.g., infiltration capacity, surface storage capacity, stream density). Stream-connected surface water can leave via stream flow, influencing the rate at which surface-water may leave a location, therefore stream-connected and disconnected surface water were analyzed separately. Stream-connected surface water responded more strongly to wetter climatic conditions (i.e., accumulated) in landscapes with more lakes and less artificial drainage (e.g., ditching, tile drainage). Disconnected surface water responded more strongly to wetter climatic conditions when landscapes contained greater wetland density, fewer streams and a lower predicted rate of infiltration. From these findings, we can expect that the relationship between upstream and downstream waters will require consideration of hydrology-related landscape characteristics, and that climate-change related shifts in precipitation and evaporative demand will have an uneven effect on surface water expansion and contraction across the landscape.

Metagenomic sequencing of two salton sea microbiomes.

PubMed

Hawley, Erik R; Schackwitz, Wendy; Hess, Matthias

2014-01-23

The Salton Sea is the largest inland body of water in California, with salinities ranging from brackish freshwater to hypersaline. The lake experiences high nutrient input, and its surface water is exposed to temperatures up to 40°C. Here, we report the community profiles associated with surface water from the Salton Sea.

Input and fate of anthropogenic estrogens and gadolinium in surface water and sewage plants in the hydrological basin of Prague (Czech Republic).

PubMed

Morteani, Giulio; Möller, Peter; Fuganti, Andrea; Paces, Tomas

2006-06-01

The concentration of the estrogens 17beta-estradiol, estriol, estrone, 17alpha-ethinylestradiol, mestranol and norethisterone and of the anthropogenic gadolinium (Gd(ant)) has been determined in the creeks and rivers, sewage treatment plants and water works of the city of Prague. The rapid degradation of estrogens in surface water allows the estrogen concentration gradient to be used as a very precise and sensitive guideline by which to pin-point sewage leaks into surface run-off water. The rather conservative behavior of Gd(ant) in surface and ground water documents in the present case the presence of sewage water in the surface water cycle.

Modeling diffuse sources of surface water contamination with plant protection products

NASA Astrophysics Data System (ADS)

Wendland, Sandra; Bock, Michael; Böhner, Jürgen; Lembrich, David

2015-04-01

Entries of chemical pollutants in surface waters are a serious environmental problem. Among water pollutants plant protection products (ppp) from farming practice are of major concern not only for water suppliers and environmental agencies, but also for farmers and industrial manufacturers. Lost chemicals no longer fulfill their original purpose on the field, but lead to severe damage of the environment and surface waters. Besides point-source inputs of chemical pollutants, the diffuse-source inputs from agricultural procedures play an important and not yet sufficiently studied role concerning water quality. The two most important factors for diffuse inputs are erosion and runoff. The latter usually occurs before erosion begins, and is thus often not visible in hindsight. Only if it has come to erosion, it is obvious to expect runoff in foresight at this area, too. In addition to numerous erosion models, there are also few applications to model runoff processes available. However, these conventional models utilize approximations of catchment parameters based on long-term average values or theoretically calculated concentration peaks which can only provide indications to relative amounts. Our study aims to develop and validate a simplified spatially-explicit dynamic model with high spatiotemporal resolution that enables to measure current and forecast runoff potential not only at catchment scale but field-differentiated. This method allows very precise estimations of runoff risks and supports risk reduction measures to be targeted before fields are treated. By focusing on water pathways occurring on arable land, targeted risk reduction measures like buffer strips at certain points and adapted ppp use can be taken early and pollution of rivers and other surface waters through transported pesticides, fertilizers and their products could be nearly avoided or largely minimized. Using a SAGA-based physical-parametric modeling approach, major factors influencing runoff (relief, soil properties, weather conditions and crop coverage) are represented. Water balance parameters are modeled in daily steps, taking into account relief determined discharge pathways, runoff velocity and number of field boundaries passed until receiving streams are reached. Model development is based on a comprehensive monitoring campaign at 3 smaller catchments in North Rhine-Westphalia (Germany), equipped with two gauges each, upstream and downstream, an optical Trios probe and four Isco-Samplers. The temporal high resolution monitoring of discharge, ppp, orthophosphate and nitrate-nitrogen enables an evaluation of runoff simulations in relation with rain events. First model results suggest that the simulation of surface runoff pathways enables a spatial-explicit identification of fields contributing to pollutant inputs. We assume that targeted actions on few fields will help solving the problem of diffuse inputs of ppp in our surface water to a considerable extent.

Spatio-temporal variability in the freshwater input to the surface water of Southern Ocean

NASA Astrophysics Data System (ADS)

Naidu, P. K.; Ghosh, P.; N, A.

2015-12-01

Ocean heat content is rising rapidly in high-latitude regions of both hemispheres as a consequence of global warming (e.g., Gille 2002; Karcher et al. 2003; Bindoff et al. 2007; Purkey and Johnson 2010). Recent warming and freshening of Southern Ocean has affected hydrological cycle in terms of increasing tendency of precipitation as liquid water instead of snow. Limited data is available on the extent of fresh water flux by precipitation and sea ice melting to the surface ocean. The spatial extent of sea ice formation is documented based on remote sensing observation. We investigate here spatial variability in freshwater inputs to the Indian sector of Southern Ocean region using combined observation of oxygen isotopes ratios and salinity of surface water during the summer of 2011, 2012 and 2013. Together with this, the measured isotopic ratios of meteoric water and sea ice melt were used in the mass balance equation for deriving the contribution of both of these components in the surface water of southern ocean. The three component mixing equations (Meredith et al., 2013) allowed estimation of fractional contribution of rain over the years. The δ18O of meteoric water followed the pattern nearly similar to the observation documented in the continental stations (Global Network of Isotopes in Precipitation, GNIP) located in the southern hemisphere. However, a slight but consistent heavier composition was documented in rainwater as compared to the GNIP stations. Our observation suggests that the meteoric water is the dominant freshwater source over the ocean, accounting for up to 10-15% of the water present in the surface ocean during the austral summer whereas Sea-ice melt accounts for a much smaller percentage (maximum around 1%). Our observation is consistent with previous studies where similar magnitude of fresh water input was proposed based on observation from coastal region (Meredith et al., 2013).

Urban and agricultural contribution of annual loads of glyphosate and AMPA towards surface waters at the Orge River catchment scale (France)

NASA Astrophysics Data System (ADS)

Botta, Fabrizio; Chevreuil, Marc; Blanchoud, Hélène

2010-05-01

The general use of pesticides in the Orge Basin, located in the southern part of the Paris suburb (France), is damaging surface water quality. Consequently, an increase in the water supply costs is registered by the water supply agencies that are situated downstream the Orge confluence with the Seine River. In this catchment, high uses of glyphosate are registered for fallow fields (upstream part) and for roadway weed control (downstream part). The proportion of glyphosate coming from these two zones was not well known, along with the double source of its metabolite AMPA originated from the degradation of some detergent phosphonates. The aim of this work was firstly to identify the potential sources of glyphosate and AMPA in urban sectors (such as sewerage system inputs) and in agricultural areas and to quantify the origins of urban pesticides pathways towards surface waters at the basin scale. The new approach of this project was to collect information at three different scales to establish a first step of modeling. At the basin scale, 1 year of surface water monitoring at the outlet of the Orge River was useful to establish the inputs towards the Seine River. At the urban catchment scale, the investigations have permitted to record glyphosate and AMPA loads transferred by storm waters and by wastewaters. Loads were estimated during and out of application calendar, in different hydrological conditions such as rainfall with high intensity or dry conditions. Impact of WWTP on surface water was also demonstrated. The third phase of this work was the interpretation of agricultural inputs from two different agricultural catchments of the Orge River. The results showed the impact of urban uses of glyphosate upon the Orge River contamination with annual loads from 100 times higher from the urban zone than from the agricultural one. Storm sewers were recognized to be the main way for glyphosate transfer towards surface waters. A budget of glyphosate and AMPA inputs and exported amounts was carried out at the River scale. Different origins (agricultural zones, urban areas and wastewater treatment plants) were assessed to determine the contribution of each usage. These investigations showed the high impact of storm waters and wastewaters upon the Orge River contamination (90%), whereas the agricultural zone contributed to only 10 % of the glyphosate contamination of the River. Glyphosate contaminates the river by direct flow of rainfall sewers towards surface waters. AMPA in the Orge river originates from both degradation of glyphosate in agricultural soils (29%) and from urban sewers (79%). Glyphosate amount transferred via overflows between sewers is the main source (more than 95%) in wastewaters during application period and rainfall events, but represents only 50% of the annual load in wastewaters that reach treatment plants (WWTP). AMPA, always detected in wastewaters and WWTP, is partly related to domestic wastewaters (18 to 23% of the total load). A difference between glyphosate and AMPA load inputs in the Orge River and outputs load at the outlet was registered: Glyphosate load is decreasing downstream as AMPA is increasing, suggesting a degradation of glyphosate into the river. The rule of sediments could have a significant influence of the dynamic transport of glyphosate. The results of the budget calculation are supported by a strong and logical data collection, coupled with detailed spatial information and consciousness of estimation accuracy. Keywords: Catchment, glyphosate, AMPA, inputs, budget

Integrated Water Flow Model (IWFM), A Tool For Numerically Simulating Linked Groundwater, Surface Water And Land-Surface Hydrologic Processes

NASA Astrophysics Data System (ADS)

Dogrul, E. C.; Brush, C. F.; Kadir, T. N.

2006-12-01

The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D land surface, lake, stream flow and vertical unsaturated-zone flow processes which are solved simultaneously at each time step. The groundwater flow system is simulated as a multilayer aquifer system with a mixture of confined and unconfined aquifers separated by semiconfining layers. The groundwater flow process can simulate changing aquifer conditions (confined to unconfined and vice versa), subsidence, tile drains, injection wells and pumping wells. The land surface process calculates elemental water budgets for agricultural, urban, riparian and native vegetation classes. Crop water demands are dynamically calculated using distributed soil properties, land use and crop data, and precipitation and evapotranspiration rates. The crop mix can also be automatically modified as a function of pumping lift using logit functions. Surface water diversions and groundwater pumping can each be specified, or can be automatically adjusted at run time to balance water supply with water demand. The land-surface process also routes runoff to streams and deep percolation to the unsaturated zone. Surface water networks are specified as a series of stream nodes (coincident with groundwater nodes) with specified bed elevation, conductance and stage-flow relationships. Stream nodes are linked to form stream reaches. Stream inflows at the model boundary, surface water diversion locations, and one or more surface water deliveries per location are specified. IWFM routes stream flows through the network, calculating groundwater-surface water interactions, accumulating inflows from runoff, and allocating available stream flows to meet specified or calculated deliveries. IWFM utilizes a very straight-forward input file structure, allowing rapid development of complex simulations. A key feature of IWFM is a new algorithm for computation of groundwater flow across element faces. Enhancements to version 3.0 include automatic time-tracking of input and output data sets, linkage with the HEC-DSS database, and dynamic crop allocation using logit functions. Utilities linking IWFM to the PEST automated calibration suite are also available. All source code, executables and documentation are available for download from the DWR web site. IWFM is currently being used to develop hydrologic simulations of California's Central Valley (C2VSIM); the west side of California's San Joaquin Valley (WESTSIM); Butte County, CA; Solano County, CA; Merced County, CA; and the Oregon side of the Walla Walla River Basin.

Surface models for coupled modelling of runoff and sewer flow in urban areas.

PubMed

Ettrich, N; Steiner, K; Thomas, M; Rothe, R

2005-01-01

Traditional methods fail for the purpose of simulating the complete flow process in urban areas as a consequence of heavy rainfall and as required by the European Standard EN-752 since the bi-directional coupling between sewer and surface is not properly handled. The new methodology, developed in the EUREKA-project RisUrSim, solves this problem by carrying out the runoff on the basis of shallow water equations solved on high-resolution surface grids. Exchange nodes between the sewer and the surface, like inlets and manholes, are located in the computational grid and water leaving the sewer in case of surcharge is further distributed on the surface. Dense topographical information is needed to build a model suitable for hydrodynamic runoff calculations; in urban areas, in addition, many line-shaped elements like houses, curbs, etc. guide the runoff of water and require polygonal input. Airborne data collection methods offer a great chance to economically gather densely sampled input data.

Earth resources evaluation for New Mexico by LANDSAT-2

NASA Technical Reports Server (NTRS)

Vonderlinden, K. (Principal Investigator); Feldman, S. C.; Inglis, M. H.; Tabet, D.; Kottlowski, F. E.

1975-01-01

The author has identified the following significant results. A cost effective technique is considered for measuring and monitoring surface area fluctuations in lake size in southeastern New Mexico over a two year period. The lakes are shallow, and therefore a small volume increase results in a noticeable increase in surface area on the LANDSAT imagery. Lake sizes are measured on an I(2)S Digicol viewer. Water from potash mining operations is being pumped into some of these lakes and the input volume is documented. Using water input and surface contour as well as direct lake level measurements as ground truth as well as the LANDSAT images, calculations may be possible regarding how much additional industrial water can be added to these lakes without the occurrence of saline see page into the major river system.

Characterization of Missouri surface waters near point sources of pollution reveals potential novel atmospheric route of exposure for bisphenol A and wastewater hormonal activity pattern.

PubMed

Kassotis, Christopher D; Alvarez, David A; Taylor, Julia A; vom Saal, Frederick S; Nagel, Susan C; Tillitt, Donald E

2015-08-15

Surface water contamination by chemical pollutants increasingly threatens water quality around the world. Among the many contaminants found in surface water, there is growing concern regarding endocrine disrupting chemicals, based on their ability to interfere with some aspect of hormone action in exposed organisms, including humans. This study assessed water quality at several sites across Missouri (near wastewater treatment plants and airborne release sites of bisphenol A) based on hormone receptor activation potencies and chemical concentrations present in the surface water. We hypothesized that bisphenol A and ethinylestradiol would be greater in water near permitted airborne release sites and wastewater treatment plant inputs, respectively, and that these two compounds would be responsible for the majority of activities in receptor-based assays conducted with water collected near these sites. Concentrations of bisphenol A and ethinylestradiol were compared to observed receptor activities using authentic standards to assess contribution to total activities, and quantitation of a comprehensive set of wastewater compounds was performed to better characterize each site. Bisphenol A concentrations were found to be elevated in surface water near permitted airborne release sites, raising questions that airborne releases of BPA may influence nearby surface water contamination and may represent a previously underestimated source to the environment and potential for human exposure. Estrogen and androgen receptor activities of surface water samples were predictive of wastewater input, although the lower sensitivity of the ethinylestradiol ELISA relative to the very high sensitivity of the bioassay approaches did not allow a direct comparison. Wastewater-influenced sites also had elevated anti-estrogenic and anti-androgenic equivalence, while sites without wastewater discharges exhibited no antagonist activities. Published by Elsevier B.V.

Characterization of Missouri surface waters near point sources of pollution reveals potential novel atmospheric route of exposure for bisphenol A and wastewater hormonal activity pattern

USGS Publications Warehouse

Kassotis, Christopher D.; Alvarez, David A.; Taylor, Julia A.; vom Saal, Frederick S.; Nagel, Susan C.; Tillitt, Donald E.

2015-01-01

Surface water contamination by chemical pollutants increasingly threatens water quality around the world. Among the many contaminants found in surface water, there is growing concern regarding endocrine disrupting chemicals, based on their ability to interfere with some aspect of hormone action in exposed organisms, including humans. This study assessed water quality at several sites across Missouri (near wastewater treatment plants and airborne release sites of bisphenol A) based on hormone receptor activation potencies and chemical concentrationspresent in the surface water. We hypothesized that bisphenol A and ethinylestradiol would be greater in water near permitted airborne release sites and wastewater treatment plant inputs, respectively, and that these two compounds would be responsible for the majority of activities in receptor-based assays conducted with water collected near these sites. Concentrations of bisphenol A and ethinylestradiol were compared to observed receptor activities using authentic standards to assess contribution to total activities, and quantitation of a comprehensive set of wastewater compounds was performed to better characterize each site. Bisphenol A concentrations were found to be elevated in surface water near permitted airborne release sites, raising questions that airborne releases of BPA may influence nearby surface water contamination and may represent a previously underestimated source to the environment and potential for human exposure. Estrogen and androgen receptor activities of surface water samples were predictive of wastewater input, although the lower sensitivity of the ethinylestradiol ELISA relative to the very high sensitivity of the bioassay approaches did not allow a direct comparison. Wastewater-influenced sites also had elevated anti-estrogenic and anti-androgenic equivalence, while sites without wastewater discharges exhibited no antagonist activities.

Water mass circulation and weathering inputs in the Labrador Sea based on coupled Hf-Nd isotope compositions and rare earth element distributions

NASA Astrophysics Data System (ADS)

Filippova, Alexandra; Frank, Martin; Kienast, Markus; Rickli, Jörg; Hathorne, Ed; Yashayaev, Igor M.; Pahnke, Katharina

2017-02-01

The Labrador Sea is one of the key areas for deep water formation driving the Atlantic thermohaline circulation and thus plays an important role in Northern Hemisphere climatic fluctuations. In order to better constrain the overturning processes and the origins of the distinct water masses, combined dissolved Hf-Nd isotopic compositions and rare earth element (REE) distribution patterns were obtained from four water depth profiles along a section across the Labrador Sea. These were complemented by one surface sample off the southern tip of Greenland, three shallow water samples off the coast of Newfoundland, and two deep water samples off Nova Scotia. Although light REEs are markedly enriched in the surface waters off the coast of Newfoundland compared to north Atlantic waters, the REE concentration profiles are essentially invariant throughout the water column across the Labrador Sea. The hafnium concentrations of surface waters exhibit a narrow range between 0.6 and 1 pmol/kg but are not significantly higher than at depth. Neodymium isotope signatures (ɛNd) vary from unradiogenic values between -16.8 and -14.9 at the surface to more radiogenic values near -11.0 at the bottom of the Labrador Sea mainly reflecting the advection of the Denmark Strait Overflow Water and North East Atlantic Deep Water, the signatures of which are influenced by weathering contributions from Icelandic basalts. Unlike Nd, water column radiogenic Hf isotope signatures (ɛHf) are more variable representing diverse weathering inputs from the surrounding landmasses. The least radiogenic seawater ɛHf signatures (up to -11.7) are found in surface waters close to Greenland and near the Canadian margin. This reflects the influence of recirculating Irminger Current Waters, which are affected by highly unradiogenic inputs from Greenland. A three to four ɛHf unit difference is observed between Denmark Strait Overflow Water (ɛHf ∼ -4) and North East Atlantic Deep Water (ɛHf ∼ -0.1), although their source waters have essentially the same ɛNd signature. This most likely reflects different weathering signals of hafnium delivered to Denmark Strait Overflow Water and North East Atlantic Deep Water (incongruent weathering of old rocks from Greenland versus basaltic rocks from Iceland). In addition, the ɛHf data resolve two layers within the main body of Labrador Sea Water not visible in the ɛNd distribution, which are shallow Labrador Sea Water (ɛHf ∼ -2) and deep Labrador Sea Water (ɛHf ∼ -4.5). The latter layer was formed between the late 1980's and mid 1990's during the last cold state of the Labrador Sea and underwent substantial modification since its formation through the admixture of Irminger Water, Iceland Slope Water and North East Atlantic Deep Water, which is reflected in its less radiogenic ɛHf signature. The overall behavior of Hf in the water column suggests its higher sensitivity to local changes in weathering inputs on annual to decadal timescales. Although application of Hf isotopes as a tracer for global water mass mixing is complicated by their susceptibility to incongruent weathering inputs they are a promising tracer of local processes in restricted basins such as the Labrador Sea.

Stable isotopic and geochemical variability within shallow groundwater beneath a hardwood hammock and surface water in an adjoining slough (Everglades National Park, Florida, USA).

PubMed

Florea, Lee J; McGee, Dorien K

2010-06-01

Data from a 10-month monitoring study during 2007 in the Everglades ecosystem provide insight into the variation of delta(18)O, deltaD, and ion chemistry in surface water and shallow groundwater. Surface waters are sensitive to dilution from rainfall and input from external sources. Shallow groundwater, on the other hand, remains geochemically stable during the year. Surface water input from canals derived from draining agricultural areas to the north and east of the Everglades is evident in the ion data. delta(18)O and deltaD values in shallow groundwater remain near the mean of-2.4 and-12 per thousand, respectively. (18)O and D values are enriched in surface water compared with shallow groundwater and fluctuate in sync with those measured in rainfall. The local meteoric water line (LMWL) for precipitation is in close agreement with the global meteoric water line; however, the local evaporation line (LEL) for surface water and shallow groundwater is delta D=5.6 delta(18)O+1.5, a sign that these waters have experienced evaporation. The intercept of the LMWL and LEL indicates that the primary recharge to the Everglades is tropical cyclones or fronts. delta deuterium to delta(18)O excess (D(ex) values) generally reveal two moisture sources for precipitation, a maritime source during the fall and winter (D (ex)>10 per thousand) and a continental-influenced source (D (ex)<10 per thousand) in the spring and summer.

Narrow pH Range of Surface Water Bodies Receiving Pesticide Input in Europe.

PubMed

Bundschuh, Mirco; Weyers, Arnd; Ebeling, Markus; Elsaesser, David; Schulz, Ralf

2016-01-01

Fate and toxicity of the active ingredients (AI's) of plant protection products in surface waters is often influenced by pH. Although a general range of pH values is reported in literature, an evaluation targeting aquatic ecosystems with documented AI inputs is lacking at the larger scale. Results show 95% of European surface waters (n = 3075) with a documented history of AI exposure fall within a rather narrow pH range, between 7.0 and 8.5. Spatial and temporal variability in the data may at least be partly explained by the calcareous characteristics of parental rock material, the affiliation of the sampling site to a freshwater ecoregion, and the photosynthetic activity of macrophytes (i.e., higher pH values with photosynthesis). Nonetheless, the documented pH range fits well with the standard pH of most ecotoxicological test guidelines, confirming the fate and ecotoxicity of AIs are usually adequately addressed.

Greenhouse gas emissions are enhanced by wastewater discharge into New York City coastal estuaries

NASA Astrophysics Data System (ADS)

Brigham, B. A.; O'Mullan, G. D.; Bird, J. A.

2016-12-01

The Hudson River Estuary (HRE) receives significant inputs of untreated wastewater from sewer overflow from New York City (NYC) and other urban areas. These inputs deliver large, concentrated pulses of carbon (C) and nitrogen (N) into the estuary primarily during storm events. We hypothesized that sewage inputs would increase carbon dioxide (CO2) and methane (CH4) efflux from the HRE via two mechanism: (1) direct input of these gases into estuarine surface waters from NYC's wastewater treatment system; and (2) indirect in-situ microbial production in response to the C and N additions. To test these hypotheses, CO2, CH4, dissolved organic C and inorganic N concentrations were measured in both sewage outflow and in estuarine waters. Efflux of CO2 and CH4 were also quantified from sediment cores sampled from Flushing Bay (FB), which is in close proximity to sewage delivery outlets. Wastewater discharge was found to be both a direct input in wastewater and an indirect source of CO2 and CH4 via microbial respiration. Effluent concentrations of CH4 (125 ppm), CO2 (2200 ρCO2), dissolved organic C, ammonium, and nitrate surface water concentrations, were a minimum of 3 times greater than in estuarine surface water adjacent to the sewage delivery area and up to 20 times greater than concentrations found in regional HRE surface waters. Incubation experiments with FB sediment demonstrated that acetate additions stimulated CO2 efflux by + 1.25 and CH4 efflux by +10 times, compared with unamended controls. The magnitude of CH4 produced was +40 times greater than from sediments incubated from a non-sewage affected area with similar salinity levels. However, total C mineralization (6 µg C day-1 g-1 of dry soil) was a small portion of the C amendment indicating negligible priming. These data warrant study on larger regional scales to assess the broader climate impact likely driven by CH4 efflux that results from discharge of untreated wastewater into urban estuaries.

Machine Learning and Deep Learning Models to Predict Runoff Water Quantity and Quality

NASA Astrophysics Data System (ADS)

Bradford, S. A.; Liang, J.; Li, W.; Murata, T.; Simunek, J.

2017-12-01

Contaminants can be rapidly transported at the soil surface by runoff to surface water bodies. Physically-based models, which are based on the mathematical description of main hydrological processes, are key tools for predicting surface water impairment. Along with physically-based models, data-driven models are becoming increasingly popular for describing the behavior of hydrological and water resources systems since these models can be used to complement or even replace physically based-models. In this presentation we propose a new data-driven model as an alternative to a physically-based overland flow and transport model. First, we have developed a physically-based numerical model to simulate overland flow and contaminant transport (the HYDRUS-1D overland flow module). A large number of numerical simulations were carried out to develop a database containing information about the impact of various input parameters (weather patterns, surface topography, vegetation, soil conditions, contaminants, and best management practices) on runoff water quantity and quality outputs. This database was used to train data-driven models. Three different methods (Neural Networks, Support Vector Machines, and Recurrence Neural Networks) were explored to prepare input- output functional relations. Results demonstrate the ability and limitations of machine learning and deep learning models to predict runoff water quantity and quality.

Sensory and Postural Input in the Occurrence of a Gender Difference in Orienting Liquid Surfaces

ERIC Educational Resources Information Center

Robert, Michele; Longpre, Sophie

2005-01-01

In the water-level task, both spatial skill and physical knowledge contribute to representing the surface of a liquid as horizontal irrespective of the container's tilt. Under the standard visual format of the task, men systematically surpass women at drawing correct water lines in outlines of tilted containers. The present exploratory experiments…

Biological soil crusts in deserts: A short review of their role in soil fertility, stabilization, and water relations

USGS Publications Warehouse

Belnap, Jayne

2003-01-01

Cyanobacteria and cyanolichens dominate most desert soil surfaces as the major component of biological soil crusts (BSC). BSCs contribute to soil fertility in many ways. BSC can increase weathering of parent materials by up to 100 times. Soil surface biota are often sticky, and help retain dust falling on the soil surface; this dust provides many plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. BSCs also provide roughened soil surfaces that slow water runoff and aid in retaining seeds and organic matter. They provide inputs of newly-fixed carbon and nitrogen to soils. They are essential in stabilizing soil surfaces by linking soil particles together with filamentous sheaths, enabling soils to resist both water and wind erosion. These same sheaths are important in keeping soil nutrients from becoming bound into plant-unavailable forms. Experimental disturbances applied in US deserts show soil surface impacts decrease N and C inputs from soil biota by up to 100%. The ability to hold aeolian deposits in place is compromised, and underlying soils are exposed to erosion. While most undisturbed sites show little sediment production, disturbance by vehicles or livestock produces up to 36 times more sediment production, with soil movement initiated at wind velocities well below commonly-occurring wind speeds. Winds across disturbed areas can quickly remove this material from the soil surface, thereby potentially removing much of current and future soil fertility. Thus, reduction in the cover of cyanophytes in desert soils can both reduce fertility inputs and accelerate fertility losses.

Understanding surface-water availability in the Central Valley as a means to projecting future groundwater storage with climate variability

NASA Astrophysics Data System (ADS)

Goodrich, J. P.; Cayan, D. R.

2017-12-01

California's Central Valley (CV) relies heavily on diverted surface water and groundwater pumping to supply irrigated agriculture. However, understanding the spatiotemporal character of water availability in the CV is difficult because of the number of individual farms and local, state, and federal agencies involved in using and managing water. Here we use the Central Valley Hydrologic Model (CVHM), developed by the USGS, to understand the relationships between climatic variability, surface water inputs, and resulting groundwater use over the historical period 1970-2013. We analyzed monthly surface water diversion data from >500 CV locations. Principle components analyses were applied to drivers constructed from meteorological data, surface reservoir storage, ET, land use cover, and upstream inflows, to feed multiple regressions and identify factors most important in predicting surface water diversions. Two thirds of the diversion locations ( 80% of total diverted water) can be predicted to within 15%. Along with monthly inputs, representations of cumulative precipitation over the previous 3 to 36 months can explain an additional 10% of variance, depending on location, compared to results that excluded this information. Diversions in the southern CV are highly sensitive to inter-annual variability in precipitation (R2 = 0.8), whereby more surface water is used during wet years. Until recently, this was not the case in the northern and mid-CV, where diversions were relatively constant annually, suggesting relative insensitivity to drought. In contrast, this has important implications for drought response in southern regions (eg. Tulare Basin) where extended dry conditions can severely limit surface water supplies and lead to excess groundwater pumping, storage loss, and subsidence. In addition to fueling our understanding of spatiotemporal variability in diversions, our ability to predict these water balance components allows us to update CVHM predictions before surface water data are compiled. We can then develop groundwater pumping and storage predictions in real time, and make them available to water managers. In addition, we are working toward future projections by coupling the regional CVHM to downscaled GCM output to assess future scenarios of water availability in this critical region.

Satellite Soil Moisture and Water Storage Observations Identify Early and Late Season Water Supply Influencing Plant Growth in the Missouri Watershed

NASA Astrophysics Data System (ADS)

A, G.; Velicogna, I.; Kimball, J. S.; Du, J.; Kim, Y.; Colliander, A.; Njoku, E. G.

2017-12-01

We employ an array of continuously overlapping global satellite sensor observations including combined surface soil moisture (SM) estimates from SMAP, AMSR-E and AMSR-2, GRACE terrestrial water storage (TWS), and satellite precipitation measurements, to characterize seasonal timing and inter-annual variations of the regional water supply pattern and its associated influence on vegetation growth estimates from MODIS enhanced vegetation index (EVI), AMSR-E/2 vegetation optical depth (VOD) and GOME-2 solar-induced florescence (SIF). Satellite SM is used as a proxy of plant-available water supply sensitive to relatively rapid changes in surface condition, GRACE TWS measures seasonal and inter-annual variations in regional water storage, while precipitation measurements represent the direct water input to the analyzed ecosystem. In the Missouri watershed, we find surface SM variations are the dominant factor controlling vegetation growth following the peak of the growing season. Water supply to growth responds to both direct precipitation inputs and groundwater storage carry-over from prior seasons (winter and spring), depending on land cover distribution and regional climatic condition. For the natural grassland in the more arid central and northwest watershed areas, an early season anomaly in precipitation or surface temperature can have a lagged impact on summer vegetation growth by affecting the surface SM and the underlying TWS supplies. For the croplands in the more humid eastern portions of the watershed, the correspondence between surface SM and plant growth weakens. The combination of these complementary remote-sensing observations provides an effective means for evaluating regional variations in the timing and availability of water supply influencing vegetation growth.

Application of receptor models on water quality data in source apportionment in Kuantan River Basin

PubMed Central

2012-01-01

Recent techniques in the management of surface river water have been expanding the demand on the method that can provide more representative of multivariate data set. A proper technique of the architecture of artificial neural network (ANN) model and multiple linear regression (MLR) provides an advance tool for surface water modeling and forecasting. The development of receptor model was applied in order to determine the major sources of pollutants at Kuantan River Basin, Malaysia. Thirteen water quality parameters were used in principal component analysis (PCA) and new variables of fertilizer waste, surface runoff, anthropogenic input, chemical and mineral changes and erosion are successfully developed for modeling purposes. Two models were compared in terms of efficiency and goodness-of-fit for water quality index (WQI) prediction. The results show that APCS-ANN model gives better performance with high R2 value (0.9680) and small root mean square error (RMSE) value (2.6409) compared to APCS-MLR model. Meanwhile from the sensitivity analysis, fertilizer waste acts as the dominant pollutant contributor (59.82%) to the basin studied followed by anthropogenic input (22.48%), surface runoff (13.42%), erosion (2.33%) and lastly chemical and mineral changes (1.95%). Thus, this study concluded that receptor modeling of APCS-ANN can be used to solve various constraints in environmental problem that exist between water distribution variables toward appropriate water quality management. PMID:23369363

Planetary-scale surface water detection from space

NASA Astrophysics Data System (ADS)

Donchyts, G.; Baart, F.; Winsemius, H.; Gorelick, N.

2017-12-01

Accurate, efficient and high-resolution methods of surface water detection are needed for a better water management. Datasets on surface water extent and dynamics are crucial for a better understanding of natural and human-made processes, and as an input data for hydrological and hydraulic models. In spite of considerable progress in the harmonization of freely available satellite data, producing accurate and efficient higher-level surface water data products remains very challenging. This presentation will provide an overview of existing methods for surface water extent and change detection from multitemporal and multi-sensor satellite imagery. An algorithm to detect surface water changes from multi-temporal satellite imagery will be demonstrated as well as its open-source implementation (http://aqua-monitor.deltares.nl). This algorithm was used to estimate global surface water changes at high spatial resolution. These changes include climate change, land reclamation, reservoir construction/decommissioning, erosion/accretion, and many other. This presentation will demonstrate how open satellite data and open platforms such as Google Earth Engine have helped with this research.

Methane Emissions from the Inland Waters of Alaska

NASA Astrophysics Data System (ADS)

Striegl, R. G.; Butman, D. E.; Stackpoole, S. M.; Dornblaser, M.

2017-12-01

Inland waters at high latitudes generally emit methane (CH4) continuously to the atmosphere during the open water season and build-up CH4 under ice during winter that is released over a short period following ice melt. Landscape position, stream and river size, water source, and turbulence created by water flow largely control CH4 emissions from streams and rivers. Organic carbon sources for CH4 production in lakes vary widely among lakes and landscapes and include hydrologic inputs from terrestrial sources, releases from permafrost thaw (thermokarst), and autochthonous inputs from aquatic macrophytes and algae. Lake emissions are therefore controlled by the balance between within-lake CH4 production and consumption, surface turbulence at the water-air interface, and CH4 ebullition. This creates a complex range of conditions that are difficult to characterize, where dissolved CH4 concentrations may vary by up to 4 orders of magnitude among lakes and/or within a single lake over an annual seasonal cycle. Moreover, large inputs of organic matter from permafrost thaw or other sources commonly result in high rates of bubble production and ebullition from some lakes, while other lakes have negligible ebullition. We quantified water surface areas and estimated CH4 emission rates for lakes, streams and rivers for the six major hydrologic regions of Alaska and determined that they collectively emit about 0.124 Tg C per year as CH4 to the atmosphere. Lake emissions comprise about 75% of the total. When adjusted for total land surface area in Alaska, our lake emission estimate is substantially smaller than previous global estimates for inland waters north of 50 degrees North latitude. We attribute this to incorporation of results that cover a broad range of lake conditions in interior Alaska and to new data from lakes in southwest Alaska that have very low CH4 concentration but very large surface area.

Processes regulating watershed chemical export during snowmelt, fraser experimental forest, Colorado

USGS Publications Warehouse

Stottlemyer, R.

2001-01-01

In the Central Rocky Mountains, snowfall dominates precipitation. Airborne contaminants retained in the snowpack can affect high elevation surface water chemistry during snowmelt. At the Fraser Experimental Forest (FEF), located west of the Continental Divide in Central Colorado, snowmelt dominates the annual hydrograph, and accounts for >95% of annual stream water discharge. During the winters of 1989-1993, we measured precipitation inputs, snowpack water equivalent (SWE) and ion content, and stream water chemistry every 7-10 days along a 3150-3500 m elevation gradient in the subalpine and alpine Lexen Creek watershed. The study objectives were to (1) quantify the distribution of SWE and snowpack chemical content with elevation and aspect, (2) quantify snowmelt rates, temperature of soil, snowpack, and air with elevation and aspect, and (3) use change in upstream-downstream water chemistry during snowmelt to better define alpine and subalpine flowpaths. The SWE increased with elevation (P - 3??C) temperatures throughout winter which resulted in significant snowpack ion loss. By snowpack PWE in mid May, the snowpack had lost almost half the cumulative precipitation H+, NH4+, and SO42- inputs and a third of the NO3- input. Windborne soil particulate inputs late in winter increased snowpack base cation content. Variation in subalpine SWE and snowpack ion content with elevation and aspect, and wind redistribution of snowfall in the alpine resulted in large year-to-year differences in the timing and magnitude of SWE, PWE, and snowpack ion content. The alpine stream water ion concentrations changed little during snowmelt indicating meltwater passed quickly through surface porous soils and was well mixed before entering the stream. Conversely, subalpine stream water chemistry was diluted during snowmelt suggesting much melt water moved to the stream as shallow subsurface lateral flow. Published by Elsevier Science B.V.

Spatial heterogeneity of mobilization processes and input pathways of herbicides into a brook in a small agricultural catchment

NASA Astrophysics Data System (ADS)

Doppler, Tobias; Lück, Alfred; Popow, Gabriel; Strahm, Ivo; Winiger, Luca; Gaj, Marcel; Singer, Heinz; Stamm, Christian

2010-05-01

Soil applied herbicides can be transported from their point of application (agricultural field) to surface waters during rain events. There they can have harmful effects on aquatic species. Since the spatial distribution of mobilization and transport processes is very heterogeneous, the contributions of different fields to the total load in a surface water body may differ considerably. The localization of especially critical areas (contributing areas) can help to efficiently minimize herbicide inputs to surface waters. An agricultural field becomes a contributing area when three conditions are met: 1) herbicides are applied, 2) herbicides are mobilized on the field and 3) the mobilized herbicides are transported rapidly to the surface water. In spring 2009, a controlled herbicide application was performed on corn fields in a small (ca 1 km2) catchment with intensive crop production in the Swiss plateau. Subsequently water samples were taken at different locations in the catchment with a high temporal resolution during rain events. We observed both saturation excess and hortonian overland flow during the field campaign. Both can be important mobilization processes depending on the intensity and quantity of the rain. This can lead to different contributing areas during different types of rain events. We will show data on the spatial distribution of herbicide loads during different types of rain events. Also the connectivity of the fields with the brook is spatially heterogeneous. Most of the fields are disconnected from the brook by internal sinks in the catchment, which prevents surface runoff from entering the brook directly. Surface runoff from these disconnected areas can only enter the brook rapidly via macropore-flow into tile drains beneath the internal sinks or via direct shortcuts to the drainage system (maintenance manholes, farmyard or road drains). We will show spatially distributed data on herbicide concentration in purely subsurface systems which shows how important such input pathways can be.

Simulating water and nitrogen loss from an irrigated paddy field under continuously flooded condition with Hydrus-1D model.

PubMed

Yang, Rui; Tong, Juxiu; Hu, Bill X; Li, Jiayun; Wei, Wenshuo

2017-06-01

Agricultural non-point source pollution is a major factor in surface water and groundwater pollution, especially for nitrogen (N) pollution. In this paper, an experiment was conducted in a direct-seeded paddy field under traditional continuously flooded irrigation (CFI). The water movement and N transport and transformation were simulated via the Hydrus-1D model, and the model was calibrated using field measurements. The model had a total water balance error of 0.236 cm and a relative error (error/input total water) of 0.23%. For the solute transport model, the N balance error and relative error (error/input total N) were 0.36 kg ha -1 and 0.40%, respectively. The study results indicate that the plow pan plays a crucial role in vertical water movement in paddy fields. Water flow was mainly lost through surface runoff and underground drainage, with proportions to total input water of 32.33 and 42.58%, respectively. The water productivity in the study was 0.36 kg m -3 . The simulated N concentration results revealed that ammonia was the main form in rice uptake (95% of total N uptake), and its concentration was much larger than for nitrate under CFI. Denitrification and volatilization were the main losses, with proportions to total consumption of 23.18 and 14.49%, respectively. Leaching (10.28%) and surface runoff loss (2.05%) were the main losses of N pushed out of the system by water. Hydrus-1D simulation was an effective method to predict water flow and N concentrations in the three different forms. The study provides results that could be used to guide water and fertilization management and field results for numerical studies of water flow and N transport and transformation in the future.

Oceans Apart: Using Stable Isotopes to Assess the Role of Fog in Two Semi-Arid Island Ecosystems

NASA Astrophysics Data System (ADS)

Schmitt, S.; Riveros-Iregui, D.; Hu, J.

2017-12-01

Fog is a significant hydrologic input in many tropical island systems, and is a water source particularly susceptible to the effects of global climate change. To better understand the role of fog as a hydrological input in two oceanic islands, we address two principal questions: 1) Do seasonal or extreme precipitation events lead to distinguishable differences in stable isotopic signatures of water inputs within and between sites and islands? 2) Does microclimatic zonation lead to distinguishable differences in isotopic signatures of meteoric inputs between different sites on a given island? To perform this analysis, meteoric water samples (fog, rain and throughfall) were collected over three sites (one windward and two leeward) and three field seasons in San Cristobal, Galapagos to ascertain the isotopic signature of each water balance input during different times of year. An additional field season of data in Ascension Island, UK, was also used to perform a comparative analysis between islands. A stable isotope mixing model was used to determine the relative proportion of surface water and groundwater that is composed of fog, and to demonstrate spatiotemporal patterns of recharge dynamics in each island system. Local meteoric water lines were generated for each site and over each field season to determine the source of hydrologic inputs (trade wind-generated orographic precipitation versus storm precipitation) and the role of locally recycled water in the overall water balance of each site. Our results will approximate potential changes in water inputs to San Cristobal and Ascension, respectively, that could be impacted by an increase in cloud base height or a change in weather patterns brought about by climate change.

Estimation of Missing Water-Level Data for the Everglades Depth Estimation Network (EDEN)

USGS Publications Warehouse

Conrads, Paul; Petkewich, Matthew D.

2009-01-01

The Everglades Depth Estimation Network (EDEN) is an integrated network of real-time water-level gaging stations, ground-elevation models, and water-surface elevation models designed to provide scientists, engineers, and water-resource managers with current (2000-2009) water-depth information for the entire freshwater portion of the greater Everglades. The U.S. Geological Survey Greater Everglades Priority Ecosystems Science provides support for EDEN and their goal of providing quality-assured monitoring data for the U.S. Army Corps of Engineers Comprehensive Everglades Restoration Plan. To increase the accuracy of the daily water-surface elevation model, water-level estimation equations were developed to fill missing data. To minimize the occurrences of no estimation of data due to missing data for an input station, a minimum of three linear regression equations were developed for each station using different input stations. Of the 726 water-level estimation equations developed to fill missing data at 239 stations, more than 60 percent of the equations have coefficients of determination greater than 0.90, and 92 percent have an coefficient of determination greater than 0.70.

Impact of water use efficiency on eddy covariance flux partitioning using correlation structure analysis

USDA-ARS?s Scientific Manuscript database

Partitioned land surfaces fluxes (e.g. evaporation, transpiration, photosynthesis, and ecosystem respiration) are needed as input, calibration, and validation data for numerous hydrological and land surface models. However, one of the most commonly used techniques for measuring land surface fluxes,...

Porewater inputs drive Fe redox cycling in the water column of a temperate mangrove wetland

NASA Astrophysics Data System (ADS)

Holloway, Ceylena J.; Santos, Isaac R.; Rose, Andrew L.

2018-07-01

Iron is a vital micronutrient within coastal marine ecosystems, playing an integral role in the scale and dynamics of primary production and carbon cycling in the world's oceans. We investigated the relative importance of in situ Fe(II) production from photochemical, microbial and thermal Fe reduction in the surface water column as well as advective porewater inputs in a temperate saline wetland in Australia containing mangrove and saltmarsh vegetation. The diel average concentration of Fe(II) (0.63 ± 0.21 μM, accounting for >70% of the total dissolved Fe present in surface water) was much higher than commonly reported in oxygenated marine waters despite high dissolved oxygen concentrations (81-112% saturation), pH (7.7-7.8) and salinity (33-36) that favor Fe oxidation. In situ production of Fe(II) in the surface water column was primarily driven by microbial processes rather than photochemical and thermal reduction, with a maximum production rate of 4.9 × 10-3 nM s-1. Advective porewater Fe(II) inputs to the wetland averaged over a diel cycle (3.0 × 10-1 nM s-1) were an order of magnitude greater than the combined Fe(II) production rate from autochthonous water column processes (1.0 × 10-2 nM s-1). A bottom up model based on the estimated individual fluxes was used to explain the high Fe(II) concentrations measured during a 24 h time series experiment. Combined, different lines of evidence suggest that advective porewater exchange provides significant quantities of Fe(II) to the estuarine wetland.

From Drought to Flood: An Analysis of the Water Balance of the Tuolumne River Basin During Extreme Conditions (2015 - 2017)

NASA Astrophysics Data System (ADS)

Hedrick, A. R.; Marks, D. G.; Havens, S.; Robertson, M.; Johnson, M.; Sandusky, M.; Bormann, K. J.; Painter, T. H.

2017-12-01

Closing the water balance of a snow-dominated mountain basin has long been a focal point of the hydrologic sciences. This study attempts to more precisely quantify the solid precipitation inputs to a basin using the iSnobal energy balance snowmelt model and assimilated snow depth information from the Airborne Snow Observatory (ASO). Throughout the ablation seasons of three highly dissimilar consecutive water years (2015 - 2017), the ASO captured high resolution snow depth snapshots over the Tuolumne River Basin in California's Central Sierra Nevada. These measurements were used to periodically update the snow depth state variable of iSnobal, thereby nudging the estimates of water storage (snow water equivalent, or SWE) and melt (surface water input, or SWI) toward a more accurate solution. Once precipitation inputs and streamflow outputs are better constrained, the additional loss terms of the water mass balance equation (i.e. groundwater recharge and evapotranspiration) can be estimated with less uncertainty.

Millennial-scale changes of surface and bottom water conditions in the northwestern Pacific during the last deglaciation

NASA Astrophysics Data System (ADS)

Kim, Sunghan; Khim, Boo-Keun; Ikehara, Ken; Itaki, Takuya; Shibahara, Akihiko; Yamamoto, Masanobu

2017-07-01

Changes in water column conditions in the northwestern Pacific during the last 23 ka were reconstructed using geochemical and isotope proxies and redox elemental compositions along with published data (alkenone sea surface temperature (SST) and benthic foraminiferal fauna) at core GH02-1030. Surface water primary productivity in terms of biogenic opal and TOC contents, which mainly represented export production of diatom, was closely related to alkenone (spring-summer) SST and the development of spring-summer mixed layer depth. The different variation patterns of nitrate and silicic acid utilization, estimated by bulk δ15N and δ30Sidiatom values, respectively, are most likely due to the water column denitrification influence on bulk δ15N. Dysoxic bottom water conditions occurred during the Bølling-Allerød (BA) and the Pre-Boreal (PB), which was evident by laminated sediments, abundant dysoxic benthic foraminifers, and increased redox elemental compositions. Although surface water productivity increased during the BA and PB, dysoxic bottom water conditions were caused by a combination of enhanced surface water productivity and reduced ventilation of North Pacific Intermediate Water (NPIW) in response to meltwater input from the high latitude areas. Based on records of core GH02-1030 and other cores in the northwestern Pacific, the Okhotsk Sea, and the Bering Sea, which are all proximal to the modern NPIW source region, dissolved oxygen concentrations of bottom water were more depleted during the BA than PB. Such difference was attributed to more sluggish NPIW ventilation due to more meltwater input during the BA than the PB. The opening or closure of the Bering Strait is critical to the direction of meltwater transport to the northwestern Pacific.

Runoff processes in catchments with a small scale topography

NASA Astrophysics Data System (ADS)

Feyen, H.; Leuenberger, J.; Papritz, A.; Gysi, M.; Flühler, H.; Schleppi, P.

1996-05-01

How do runoff processes influence nitrogen export from forested catchments? To support nitrogen balance studies for three experimental catchments (1500m 2) in the Northern Swiss prealps water flow processes in the two dominating soil types are monitored. Here we present the results for an experimental wetland catchment (1500m 2) and for a delineated sloped soil plot (10m 2), both with a muck humus topsoil. Runoff measurements on both the catchment and the soil plot showed fast reactions of surface and subsurface runoff to rainfall inputs, indicating the dominance of fast-flow paths such as cracks and fissures. Three quarters of the runoff from the soil plot can be attributed to water flow in the gleyic, clayey subsoil, 20% to flow in the humic A horizon and only 5% to surface runoff. The water balance for the wetland catchment was closed. The water balance of the soil plot did not close. Due to vertical upward flow from the saturated subsoil into the upper layers, the surface runoff plus subsurface runoff exceeded the input (precipitation) to the plot.

Improved simulation of river water and groundwater exchange in an alluvial plain using the SWAT model

USDA-ARS?s Scientific Manuscript database

Hydrological interaction between surface and subsurface water systems has a significant impact on water quality, ecosystems and biogeochemistry cycling of both systems. Distributed models have been developed to simulate this function, but they require detailed spatial inputs and extensive computati...

Evaluation of Uncertainty in Constituent Input Parameters for Modeling the Fate of IMX 101 Components

DTIC Science & Technology

2017-05-01

ER D C/ EL T R- 17 -7 Environmental Security Technology Certification Program (ESTCP) Evaluation of Uncertainty in Constituent Input...Environmental Security Technology Certification Program (ESTCP) ERDC/EL TR-17-7 May 2017 Evaluation of Uncertainty in Constituent Input Parameters...Environmental Evaluation and Characterization Sys- tem (TREECS™) was applied to a groundwater site and a surface water site to evaluate the sensitivity

HCMM energy budget data as a model input for assessing regions of high potential groundwater pollution. [South Dakota

NASA Technical Reports Server (NTRS)

Moore, D. G. (Principal Investigator); Heilman, J. L.

1980-01-01

The author has identified the following significant results. Significant relationships were found between surface soil temperatures estimated from HCMM radiometric temperatures and depth to ground water and near surface soil moisture.

LANDSCAPE INDICATORS OF SURFACE WATER CONDITIONS

EPA Science Inventory

This task comprises three inter-related projects: 1) impervious surface mapping and evaluation of its impact ; 2) detection of BMPs and estimation of their ability to reduce nutrient input into streams, and; 3) detection of isolated wetlands. Each substask addresses critical is...

Geohydrology and limnology of Walden Pond, Concord, Massachusetts

USGS Publications Warehouse

Colman, John A.; Friesz, Paul J.

2001-01-01

The trophic ecology and ground-water contributing area of Walden Pond, in Concord and Lincoln, Mass., were investigated by the U.S. Geological Survey in cooperation with the Massachusetts Department of Environmental Management from April 1997 to July 2000. Bathymetric investigation indicated that Walden Pond (24.88 hectares), a glacial kettle-hole lake with no surface inlet or outlet, has three deep areas. The maximum depth (30.5 meters) essentially was unchanged from measurements made by Henry David Thoreau in 1846. The groundwater contributing area (621,000 square meters) to Walden Pond was determined from water-table contours in areas of stratified glacial deposits and from land-surface contours in areas of bedrock highs. Walden Pond is a flow-through lake: Walden Pond gains water from the aquifer along its eastern perimeter and loses water to the aquifer along its western perimeter. Walden Pond contributing area also includes Goose Pond and its contributing area. A water budget calculated for Walden Pond, expressed as depth of water over the lake surface, indicated that 45 percent of the inflow to the lake was from precipitation (1.215 meters per year) and 55 percent from ground water (1.47 meters per year). The groundwater inflow estimate was based on the average of two different approaches including an isotope mass-balance approach. Evaporation accounted for 26 percent of the outflow from the lake (0.71 meters per year) whereas lake-water seepage to the groundwater system contributed 74 percent of the outflow (1.97 meters per year). The water-residence time of Walden Pond is approximately 5 years. Potential point sources of nutrients to ground water, the Concord municipal landfill and a trailer park, were determined to be outside the Walden Pond groundwater contributing area. A third source, the septic leach field for the Walden Pond State Reservation facilities, was within the groundwater contributing area. Nutrient budgets for the lake indicated that nitrogen inputs (858 kilograms per year) were dominated (30 percent) by plume water from the septic leach field and, possibly, by swimmers (34 percent). Phosphorus inputs (32 kilograms per year) were dominated by atmospheric dry deposition, background ground water, and estimated swimmer inputs. Swimmer inputs may represent more than 50 percent of the phosphorus load during the summer. The septic-system plume did not contribute phosphorus, but increased the nitrogen to phosphorus ratio for inputs from 41 to 59, on an atom-to-atom basis. The ratio of nitrogen to phosphorus in input loads and within the lake indicated algal growth would be strongly phosphorus limited. Nitrogen supply in excess of plant requirements may mitigate against nitrogen fixing organisms including undesirable blooms of cyanobacteria. Based on areal nutrient loading, Walden Pond is a mesotrophic lake. Hypolimnetic oxygen demand of Walden Pond has increased since a profile was measured in 1939. Currently (1999), the entire hypolimnion of Walden Pond becomes devoid of dissolved oxygen before fall turnover in late November; whereas historical data indicated dissolved oxygen likely remained in the hypolimnion during 1939. The complete depletion of dissolved oxygen likely causes release of phosphorus from the sediments. Walden Pond contains a large population of the deep-growing benthic macro alga Nitella, which has been hypothesized to promote water clarity in other clear-water lakes by sequestering nutrients and keeping large areas of the sediment surface oxygenated. Loss of Nitella populations in other lakes has correlated with a decline in water quality. Although the Nitella standing crop is large in Walden Pond, Nitella still appears to be controlled by nutrient availability. Decreasing phosphorus inputs to Walden Pond, by amounts under anthropogenic control would likely contribute to the stability of the Nitella population in the metalimnion, may reverse oxygen depletion in the hypolimnion, and decreas

Modelling global nitrogen export to ground and surface water from natural ecosystems: impact of N deposition, climate, and CO2 concentration

NASA Astrophysics Data System (ADS)

Braakhekke, Maarten; Rebel, Karin; Dekker, Stefan; van Beek, Rens; Bierkens, Marc; Smith, Ben; Wassen, Martin

2015-04-01

For large regions in the world strong increases in atmospheric nitrogen (N) deposition are predicted as a result of emissions from fossil fuel combustion and food production. This will cause many previously N limited ecosystems to become N saturated, leading to increased export to ground and surface water and negative impacts on the environment and human health. However, precise N export fluxes are difficult to predict. Due to its strong link to carbon, N in vegetation and soil is also determined by productivity, as affected by rising atmospheric CO2 concentration and temperature, and denitrification. Furthermore, the N concentration of water delivered to streams depends strongly on local hydrological conditions. We aim to study how N delivery to ground and surface water is affected by changes in environmental factors. To this end we are developing a global dynamic modelling system that integrates representations of N cycling in vegetation and soil, and N delivery to ground and surface water. This will be achieved by coupling the dynamic global vegetation model LPJ-GUESS, which includes representations of N cycling, as well as croplands and pasture, to the global water balance model PCR-GLOBWB, which simulates surface runoff, interflow, groundwater recharge, and baseflow. This coupling will allow us to trace N across different systems and estimate the input of N into the riverine system which can be used as input for river biogeochemical models. We will present large scale estimates of N leaching and transport to ground and surface water for natural ecosystems in different biomes, based on a loose coupling of the two models. Furthermore, by means of a factorial model experiment we will explore how these fluxes are influenced by N deposition, temperature, and CO2 concentration.

Sources of oxygen flux in groundwater during induced bank filtration at a site in Berlin, Germany

NASA Astrophysics Data System (ADS)

Kohfahl, Claus; Massmann, Gudrun; Pekdeger, Asaf

2009-05-01

The microbial degradation of pharmaceuticals found in surface water used for artificial recharge is strongly dependent on redox conditions of the subsurface. Furthermore the durability of production wells may decrease considerably with the presence of oxygen and ferrous iron due to the precipitation of trivalent iron oxides and subsequent clogging. Field measurements are presented for oxygen at a bank filtration site in Berlin, Germany, along with simplified calculations of different oxygen pathways into the groundwater. For a two-dimensional vertical cross-section, oxygen input has been calculated for six scenarios related to different water management strategies. Calculations were carried out in order to assess the amount of oxygen input due to (1) the infiltration of oxic lake water, (2) air entrapment as a result of water table oscillations, (3) diffusive oxygen flux from soil air and (4) infiltrating rainwater. The results show that air entrapment and infiltrating lake water during winter constitute by far the most important mechanism of oxygen input. Oxygen input by percolating rainwater and by diffusive delivery of oxygen in the gas phase is negligible. The results exemplify the importance of well management as a determining factor for water oscillations and redox conditions during artificial recharge.

Water Quality and Hydrology of Silver Lake, Barron County, Wisconsin, With Special Emphasis on Responses of a Terminal Lake to Changes in Phosphorus Loading and Water Level

USGS Publications Warehouse

Robertson, Dale M.; Rose, William J.; Fitzpatrick, Faith A.

2009-01-01

Silver Lake is typically an oligotrophic-to-mesotrophic, soft-water, terminal lake in northwestern Wisconsin. A terminal lake is a closed-basin lake with surface-water inflows but no surface-water outflows to other water bodies. After several years with above-normal precipitation, very high water levels caused flooding of several buildings near the lake and erosion of soil around much of the shoreline, which has been associated with a degradation in water quality (increased phosphorus and chlorophyll a concentrations and decreased water clarity). To gain a better understanding of what caused the very high water levels and degradation in water quality and collect information to better understand the lake and protect it from future degradation, the U.S. Geological Survey did a detailed study from 2004 to 2008. This report describes results of the study; specifically, lake-water quality, historical changes in water level, water and phosphorus budgets for the two years monitored in the study, results of model simulations that demonstrate how changes in phosphorus inputs affect lake-water quality, and the relative importance of changes in hydrology and changes in the watershed to the water quality of the lake. From 1987 to about 1996, water quality in Silver Lake was relatively stable. Since 1996, however, summer average total phosphorus concentrations increased from about 0.008 milligrams per liter (mg/L) to 0.018 mg/L in 2003, before decreasing to 0.011 mg/L in 2008. From 1996 to 2003, Secchi depths decreased from about 14 to 7.4 feet, before increasing to about 19 feet in 2008. Therefore, Silver Lake is typically classified as oligotrophic to mesotrophic; however, during 2002-4, the lake was classified as mesotrophic to eutrophic. Because productivity in Silver Lake is limited by phosphorus, phosphorus budgets for the lake were constructed for monitoring years 2005 and 2006. The average annual input of phosphorus was 216 pounds: 78 percent from tributary and nearshore runoff and 22 percent from atmospheric deposition. Because Silver Lake is hydraulically mounded above the local groundwater system, little or no input of phosphorus to the lake is from groundwater and septic systems. Silver Lake had previously been incorrectly described as a groundwater flowthrough lake. Phosphorus budgets were constructed for a series of dry years (low water levels) and a series of wet years (high water levels). About 6 times more phosphorus was input to the lake during wet years with high water levels than during the dry years. Phosphorus from erosion represented 13-20 percent of the phosphorus input during years with very high water levels. Results from the Canfield and Bachman eutrophication model and Carlson trophic state index equations demonstrated that water quality in Silver Lake directly responds to changes in external phosphorus input, with the percent change in chlorophyll a being about 80 percent of the percent change in total phosphorus input and the change in Secchi depth and total phosphorus concentrations being about 40 and 50 percent of the percent change in input, respectively. Therefore, changes in phosphorus input should impact water quality. Specific scenarios were simulated with the models to describe the effects of natural (climate-driven) and anthropogenic (human-induced) changes. Results of these scenarios demonstrated that several years of above-normal precipitation cause sustained high water levels and a degradation in water quality, part of which is due to erosion of the shoreline. Results also demonstrated that 1) changes in tributary and nearshore runoff have a dramatic effect on lake-water quality, 2) diverting water into the lake to increase the water level is expected to degrade the water quality, and 3) removal of water to decrease the water level of the lake is expected to have little effect on water quality. Fluctuations in water levels since 1967, when records began for the lake, are representative

Analysis of pesticides in surface water and sediment from Yolo Bypass, California, 2004-2005

USGS Publications Warehouse

Smalling, Kelly L.; Orlando, James L.; Kuivila, Kathryn

2005-01-01

Inputs to the Yolo Bypass are potential sources of pesticides that could impact critical life stages of native fish. To assess the direct inputs during inundation, pesticide concentrations were analyzed in water, in suspended and bed-sediment samples collected from six source watersheds to the Yolo Bypass, and from three sites within the Bypass in 2004 and 2005. Water samples were collected in February 2004 from the six input sites to the Bypass during the first flood event of the year representing pesticide inputs during high-flow events. Samples were also collected along a transect across the Bypass in early March 2004 and from three sites within the Bypass in the spring of 2004 under low-flow conditions. Low-flow data were used to understand potential pesticide contamination and its effects on native fish if water from these areas were used to flood the Bypass in dry years. To assess loads of pesticides to the Bypass associated with suspended sediments, large-volume water samples were collected during high flows in 2004 and 2005 from three sites, whereas bed sediments were collected from six sites in the fall of 2004 during the dry season. Thirteen current-use pesticides were detected in surface water samples collected during the study. The highest pesticide concentrations detected at the input sites to the Bypass corresponded to the first high-flow event of the year. The highest pesticide concentrations at the two sites sampled within the Bypass during the early spring were detected in mid-April following a major flood event as the water began to subside. The pesticides detected and their concentrations in the surface waters varied by site; however, hexazinone and simazine were detected at all sites and at some of the highest concentrations. Thirteen current-use pesticides and three organochlorine insecticides were detected in bed and suspended sediments collected in 2004 and 2005. The pesticides detected and their concentrations varied by site and sediment sample type. Trifluralin, p,p'-DDE, and p,p'-DDT were highest in the bed sediments, whereas oxyfluorfen and thiobencarb were highest in the suspended sediments. With the exception of the three organochlorine insecticides, suspended sediments had higher pesticide concentrations compared with bed sediments, indicating the potential for pesticide transport throughout the Bypass, especially during high-flow events. Understanding the distribution of pesticides between the water and sediment is needed to assess fate and transport within the Bypass and to evaluate the potential effects on native fish.

Watershed delineation and nitrogen source analysis for Bayou Chico, an urban watershed in northwest Florida

EPA Science Inventory

Nutrient pollution in stormwater runoff from urbanized areas contributes to water quality degradation in streams and receiving waterbodies. Agriculture, population growth, and industrial activities are significant sources of nitrogen inputs for surface waters. Increased nitrogen ...

Seasonal changes in Fe along a glaciated Greenlandic fjord.

NASA Astrophysics Data System (ADS)

Hopwood, Mark; Connelly, Douglas; Arendt, Kristine; Juul-Pedersen, Thomas; Stinchcombe, Mark; Meire, Lorenz; Esposito, Mario; Krishna, Ram

2016-03-01

Greenland's ice sheet is the second largest on Earth, and is under threat from a warming Arctic climate. An increase in freshwater discharge from Greenland has the potential to strongly influence the composition of adjacent water masses with the largest impact on marine ecosystems likely to be found within the glaciated fjords. Here we demonstrate that physical and chemical estuarine processes within a large Greenlandic fjord are critical factors in determining the fate of meltwater derived nutrients and particles, especially for non-conservative elements such as Fe. Concentrations of Fe and macronutrients in surface waters along Godthåbsfjord, a southwest Greenlandic fjord with freshwater input from 6 glaciers, changed markedly between the onset and peak of the meltwater season due to the development of a thin (<10 m), outflowing, low-salinity surface layer. Dissolved (<0.2 µm) Fe concentrations in meltwater entering Godthåbsfjord (200 nM), in freshly melted glacial ice (mean 38 nM) and in surface waters close to a land terminating glacial system (80 nM) all indicated high Fe inputs into the fjord in summer. Total dissolvable (unfiltered at pH <2.0) Fe was similarly high with concentrations always in excess of 100 nM throughout the fjord and reaching up to 5.0 µM close to glacial outflows in summer. Yet, despite the large seasonal freshwater influx into the fjord, Fe concentrations near the fjord mouth in the out-flowing surface layer were similar in summer to those measured before the meltwater season. Furthermore, turbidity profiles indicated that sub-glacial particulate Fe inputs may not actually mix into the outflowing surface layer of this fjord. Emphasis has previously been placed on the possibility of increased Fe export from Greenland as meltwater fluxes increase. Here we suggest that in-fjord processes may be effective at removing Fe from surface waters before it can be exported to coastal seas.

A NEW GIS NITROGEN TRADING TOOL CONCEPT FOR CONSERVATION AND REDUCTION OF REACTIVE NITROGEN LOSSES TO THE ENVIRONMENT

USDA-ARS?s Scientific Manuscript database

Nitrogen inputs to agricultural systems are important for their sustainability. However, when N inputs are unnecessarily high, the excess can contribute to greater agricultural N losses that impact air, surface water and groundwater quality. It is paramount to reduce off-site transport of N by using...

Effect of climate change on runoff of Campylobacter and Cryptosporidium from land to surface water.

PubMed

Sterk, Ankie; Schijven, Jack; de Roda Husman, Ana Maria; de Nijs, Ton

2016-05-15

Faeces originating from wildlife, domestic animals or manure-fertilized fields, is considered an important source of zoonotic pathogens to which people may be exposed by, for instance, bathing or drinking-water consumption. An increase in runoff, and associated wash-off of animal faeces from fields, is assumed to contribute to the increase of disease outbreaks during periods of high precipitation. Climate change is expected to increase winter precipitation and extreme precipitation events during summer, but has simultaneously also other effects such as temperature rise and changes in evapotranspiration. The question is to what extent the combination of these effects influence the input of zoonotic pathogens to the surface waters. To quantitatively analyse the impacts of climate change on pathogen runoff, pathogen concentrations reaching surface waters through runoff were calculated by combining an input model for catchment pathogen loads with the Wageningen Lowland Runoff Simulator (WALRUS). Runoff of Cryptosporidium and Campylobacter was evaluated under different climate change scenarios and by applying different scenarios for sources of faecal pollution in the catchments, namely dairy cows and geese and manure fertilization. Model evaluation of these scenarios shows that climate change has little overall impact on runoff of Campylobacter and Cryptosporidium from land to the surface waters. Even though individual processes like runoff fluxes, pathogen release and dilution are affected, either positively or negatively, the net effect on the pathogen concentration in surface waters and consequently also on infection risks through recreation seems limited. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Modeled Watershed Runoff Associated with Variations in Precipitation Data with Implications for Contaminant Fluxes

EPA Science Inventory

Watershed-scale fate and transport models are important tools for estimating the sources, transformation, and transport of contaminants to surface water systems. Precipitation is one of the primary inputs to watershed biogeochemical models, influencing changes in the water budge...

Generation of ozone by pulsed corona discharge over water surface in hybrid gas liquid electrical discharge reactor

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Janda, Vaclav; Sunka, Pavel

2005-02-01

Ozone formation by a pulse positive corona discharge generated in the gas phase between a planar high voltage electrode made from reticulated vitreous carbon and a water surface with an immersed ground stainless steel plate electrode was investigated under various operating conditions. The effects of gas flow rate (0.5-3 litre min-1), discharge gap spacing (2.5-10 mm), applied input power (2-45 W) and gas composition (oxygen containing argon or nitrogen) on ozone production were determined. Ozone concentration increased with increasing power input and with increasing discharge gap. The production of ozone was significantly affected by the presence of water vapour formed through vaporization of water at the gas-liquid interface by the action of the gas phase discharge. The highest energy efficiency for ozone production was obtained using high voltage pulses of approximately 150 ns duration in Ar/O2 mixtures with the maximum efficiency (energy yield) of 23 g kW h-1 for 40% argon content.

Understanding groundwater, surface water, and hyporheic zone biogeochemical processes in a Chalk catchment using fluorescence properties of dissolved and colloidal organic matter

NASA Astrophysics Data System (ADS)

Lapworth, D. J.; Gooddy, D. C.; Allen, D.; Old, G. H.

2009-09-01

Understanding groundwater-surface water (GW-SW) interaction in Chalk catchments is complicated by the degree of geological heterogeneity. At this study site, in southern United Kingdom, alluvial deposits in the riparian zone can be considered as a patchwork of varying grades and types with an equally varied lateral connectivity. Some display good connection with the river system and others good connection with the groundwater system and, by definition, poorer connectivity with the surface water. By coupling tangential flow fractionation (TFF) with fluorescence analysis we were able to characterize the organic matter in the river and hyporheic zone. There is a significant proportion of particulate and colloidal fluorescent organic matter (FOM) within the river system and at depth within the gravels beneath the river channel. At depth in the hyporheic zone, the surface water inputs are dampened by mixing with deeper groundwater FOM. The shallow (0-0.5 m below river bed) hyporheic zone is highly dynamic as a result of changing surface water inputs from upstream processes. Labile C in the form of protein-like FOM appears to be attenuated preferentially compared to fulvic-like fluorescence in the hyporheic zone compared to the adjacent gravel and sand deposits. These preliminary findings have important implications for understanding nutrient and trace element mobility and attenuation within the groundwater, surface water, and hyporheic zone of permeable Chalk catchments. Fluorescence analysis of dissolved organic matter has been shown to be a useful environmental tracer that can be used in conjunction with other methods to understand GW-SW processes within a permeable Chalk catchment.

Dynamic perennial firn aquifer on an Arctic glacier

NASA Astrophysics Data System (ADS)

Christianson, Knut; Kohler, Jack; Alley, Richard B.; Nuth, Christopher; Pelt, Ward J. J.

2015-03-01

Ice-penetrating radar and GPS observations reveal a perennial firn aquifer (PFA) on a Svalbard ice field, similar to those recently discovered in southeastern Greenland. A bright, widespread radar reflector separates relatively dry and water-saturated firn. This surface, the phreatic firn water table, is deeper beneath local surface elevation maxima, shallower in surface lows, and steeper where the surface is steep. The reflector crosscuts snow stratigraphy; we use the apparent deflection of accumulation layers due to the higher dielectric permittivity below the water table to infer that the firn pore space becomes progressively more saturated as depth increases. Our observations indicate that PFAs respond rapidly (subannually) to surface forcing, and are capable of providing significant input to the englacial hydrology system.

A Water-Withdrawal Input-Output Model of the Indian Economy.

PubMed

Bogra, Shelly; Bakshi, Bhavik R; Mathur, Ritu

2016-02-02

Managing freshwater allocation for a highly populated and growing economy like India can benefit from knowledge about the effect of economic activities. This study transforms the 2003-2004 economic input-output (IO) table of India into a water withdrawal input-output model to quantify direct and indirect flows. This unique model is based on a comprehensive database compiled from diverse public sources, and estimates direct and indirect water withdrawal of all economic sectors. It distinguishes between green (rainfall), blue (surface and ground), and scarce groundwater. Results indicate that the total direct water withdrawal is nearly 3052 billion cubic meter (BCM) and 96% of this is used in agriculture sectors with the contribution of direct green water being about 1145 BCM, excluding forestry. Apart from 727 BCM direct blue water withdrawal for agricultural, other significant users include "Electricity" with 64 BCM, "Water supply" with 44 BCM and other industrial sectors with nearly 14 BCM. "Construction", "miscellaneous food products"; "Hotels and restaurants"; "Paper, paper products, and newsprint" are other significant indirect withdrawers. The net virtual water import is found to be insignificant compared to direct water used in agriculture nationally, while scarce ground water associated with crops is largely contributed by northern states.

Estimating wetland connectivity to streams in the Prairie Pothole Region: An isotopic and remote sensing approach

USGS Publications Warehouse

Brooks, J. R.; Mushet, David M.; Vanderhoof, Melanie; Leibowitz, Scott G.; Neff, Brian; Christensen, J. R.; Rosenberry, Donald O.; Rugh, W. D.; Alexander, L.C.

2018-01-01

Understanding hydrologic connectivity between wetlands and perennial streams is critical to understanding the reliance of stream flow on inputs from wetlands. We used the isotopic evaporation signal in water and remote sensing to examine wetland‐stream hydrologic connectivity within the Pipestem Creek watershed, North Dakota, a watershed dominated by prairie‐pothole wetlands. Pipestem Creek exhibited an evaporated‐water signal that had approximately half the isotopic‐enrichment signal found in most evaporatively enriched prairie‐pothole wetlands. Groundwater adjacent to Pipestem Creek had isotopic values that indicated recharge from winter precipitation and had no significant evaporative enrichment, indicating that enriched surface water did not contribute significantly to groundwater discharging into Pipestem Creek. The estimated surface water area necessary to generate the evaporation signal within Pipestem Creek was highly dynamic, varied primarily with the amount of discharge, and was typically greater than the immediate Pipestem Creek surface water area, indicating that surficial flow from wetlands contributed to stream flow throughout the summer. We propose a dynamic range of spilling thresholds for prairie‐pothole wetlands across the watershed allowing for wetland inputs even during low‐flow periods. Combining Landsat estimates with the isotopic approach allowed determination of potential (Landsat) and actual (isotope) contributing areas in wetland‐dominated systems. This combined approach can give insights into the changes in location and magnitude of surface water and groundwater pathways over time. This approach can be used in other areas where evaporation from wetlands results in a sufficient evaporative isotopic signal.

Polycyclic aromatic hydrocarbons (PAHs) in the water column and sediment core of Deep Bay, South China

NASA Astrophysics Data System (ADS)

Qiu, Yao-Wen; Zhang, Gan; Liu, Guo-Qing; Guo, Ling-Li; Li, Xiang-Dong; Wai, Onyx

2009-06-01

The levels of 15 polycyclic aromatic hydrocarbons (PAHs) were determined in seawater, suspended particulate matter (SPM), surface sediment and core sediment samples of Deep Bay, South China. The average concentrations Σ 15PAHs were 69.4 ± 24.7 ng l -1 in seawater, 429.1 ± 231.8 ng g -1 in SPM, and 353.8 ± 128.1 ng g -1 dry weight in surface sediment, respectively. Higher PAH concentrations were observed in SPM than in surface sediment. Temporal trend of PAH concentrations in core sediment generally increased from 1948 to 2004, with higher concentrations in top than in sub-surface, implying a stronger recent input of PAHs owing to the rapid economic development in Shenzhen. Compared with historical data, the PAH levels in surface sediment has increased, and this was further confirmed by the increasing trend of PAHs in the core sediment. Phenanthrene, fluoranthene and pyrene dominated in the PAH composition pattern profiles in the Bay. Compositional pattern analysis suggested that PAHs in the Deep Bay were derived from both pyrogenic and petrogenic sources, and diesel oil leakage, river runoff and air deposition may serve as important pathways for PAHs input to the Bay. Significant positive correlations between partition coefficient in surface sediment to that in water ( KOC) of PAH and their octanol/water partition coefficients ( KOW) were observed, suggesting that KOC of PAHs in sediment/water of Deep Bay may be predicted by the corresponding KOW.

Geospatial application of the Water Erosion Prediction Project (WEPP) Model

Treesearch

D. C. Flanagan; J. R. Frankenberger; T. A. Cochrane; C. S. Renschler; W. J. Elliot

2011-01-01

The Water Erosion Prediction Project (WEPP) model is a process-based technology for prediction of soil erosion by water at hillslope profile, field, and small watershed scales. In particular, WEPP utilizes observed or generated daily climate inputs to drive the surface hydrology processes (infiltration, runoff, ET) component, which subsequently impacts the rest of the...

Section 1. Simulation of surface-water integrated flow and transport in two-dimensions: SWIFT2D user's manual

USGS Publications Warehouse

Schaffranek, Raymond W.

2004-01-01

A numerical model for simulation of surface-water integrated flow and transport in two (horizontal-space) dimensions is documented. The model solves vertically integrated forms of the equations of mass and momentum conservation and solute transport equations for heat, salt, and constituent fluxes. An equation of state for salt balance directly couples solution of the hydrodynamic and transport equations to account for the horizontal density gradient effects of salt concentrations on flow. The model can be used to simulate the hydrodynamics, transport, and water quality of well-mixed bodies of water, such as estuaries, coastal seas, harbors, lakes, rivers, and inland waterways. The finite-difference model can be applied to geographical areas bounded by any combination of closed land or open water boundaries. The simulation program accounts for sources of internal discharges (such as tributary rivers or hydraulic outfalls), tidal flats, islands, dams, and movable flow barriers or sluices. Water-quality computations can treat reactive and (or) conservative constituents simultaneously. Input requirements include bathymetric and topographic data defining land-surface elevations, time-varying water level or flow conditions at open boundaries, and hydraulic coefficients. Optional input includes the geometry of hydraulic barriers and constituent concentrations at open boundaries. Time-dependent water level, flow, and constituent-concentration data are required for model calibration and verification. Model output consists of printed reports and digital files of numerical results in forms suitable for postprocessing by graphical software programs and (or) scientific visualization packages. The model is compatible with most mainframe, workstation, mini- and micro-computer operating systems and FORTRAN compilers. This report defines the mathematical formulation and computational features of the model, explains the solution technique and related model constraints, describes the model framework, documents the type and format of inputs required, and identifies the type and format of output available.

Lead isotopes in the western North Atlantic: Transient tracers of pollutant lead inputs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veron, A.J.; Church, T.M.; Flegal, A.R.

1998-08-01

In the early 1980s, Patterson and colleagues demonstrated that most lead in oceanic surface waters had an anthropogenic origin. Their discovery occurred during the phasing out of leaded gasoline in North America initiated in the previous decade. The corresponding decrease in anthropogenic lead emissions, verified by Pb/{sup 210}Pb ratios, accounted for the systematic decline in lead concentrations in surface waters of the western Sargasso Sea. Subsequent changes in anthropogenic lead inputs to the western Sargasso Sea surface waters have been documented by measurements of lead concentrations, isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 206}Pb), and Pb/{sup 210}Pb ratios in precipitationmore » and seawater for the period of 1981 to 1994. These data indicate the easterly trade winds are now the primary source of atmospheric lead in Bermuda, and they confirm that the decline of lead concentrations in the North Atlantic is associated with the phasing out of leaded gasoline in North America and western Europe over the past decade. Moreover, temporal variations in the relative contribution of industrial lead inputs from the two sides of the North Atlantic over that period can be quantified based on differences in their isotopic composition. The transient character of those isotopic signatures also allows calculations of pollutant lead penetration rates into the mixed layer and upper thermocline of the western Sargasso Sea.« less

Estimating net rainfall, evaporation and water storage of a bare soil from sequential L-band emissivities

NASA Technical Reports Server (NTRS)

Stroosnijder, L.; Lascano, R. J.; Newton, R. W.; Vanbavel, C. H. M.

1984-01-01

A general method to use a time series of L-band emissivities as an input to a hydrological model for continuously monitoring the net rainfall and evaporation as well as the water content over the entire soil profile is proposed. The model requires a sufficiently accurate and general relation between soil emissivity and surface moisture content. A model which requires the soil hydraulic properties as an additional input, but does not need any weather data was developed. The method is shown to be numerically consistent.

Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

PubMed Central

Lusher, Amy L.; Tirelli, Valentina; O’Connor, Ian; Officer, Rick

2015-01-01

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment. PMID:26446348

Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

NASA Astrophysics Data System (ADS)

Lusher, Amy L.; Tirelli, Valentina; O'Connor, Ian; Officer, Rick

2015-10-01

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples.

PubMed

Lusher, Amy L; Tirelli, Valentina; O'Connor, Ian; Officer, Rick

2015-10-08

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

Sequestration of arsenic in ombrotrophic peatlands

NASA Astrophysics Data System (ADS)

Rothwell, James; Hudson-Edwards, Karen; Taylor, Kevin; Polya, David; Evans, Martin; Allott, Tim

2014-05-01

Peatlands can be important stores of arsenic but we are lacking spectroscopic evidence of the sequestration pathways of this toxic metalloid in peatland environments. This study reports on the solid-phase speciation of anthropogenically-derived arsenic in atmospherically contaminated peat from the Peak District National Park (UK). Surface and sub-surface peat samples were analysed by synchrotron X-ray absorption spectroscopy on B18 beamline at Diamond Light Source (UK). The results suggest that there are contrasting arsenic sequestration mechanisms in the peat. The bulk arsenic speciation results, in combination with strong arsenic-iron correlations at the surface, suggest that iron (hydr)oxides are key phases for the immobilisation of arsenic at the peat surface. In contrast, the deeper peat samples are dominated by arsenic sulphides (arsenopyrite, realgar and orpiment). Given that these peats receive inputs solely from the atmosphere, the presence of these sulphide phases suggests an in-situ authigenic formation. Redox oscillations in the peat due to a fluctuating water table and an abundant store of legacy sulphur from historic acid rain inputs may favour the precipitation of arsenic sequestering sulphides in sub-surface horizons. Oxidation-induced loss of these arsenic sequestering sulphur species by water table drawdown has important implications for the mobility of arsenic and the quality of waters draining peatlands.

Plio-Pleistocene evolution of water mass exchange and erosional input at the Atlantic-Arctic gateway

NASA Astrophysics Data System (ADS)

Teschner, Claudia; Frank, Martin; Haley, Brian A.; Knies, Jochen

2016-05-01

Water mass exchange between the Arctic Ocean and the Norwegian-Greenland Seas has played an important role for the Atlantic thermohaline circulation and Northern Hemisphere climate. We reconstruct past water mass mixing and erosional inputs from the radiogenic isotope compositions of neodymium (Nd), lead (Pb), and strontium (Sr) at Ocean Drilling Program site 911 (leg 151) from 906 m water depth on Yermak Plateau in the Fram Strait over the past 5.2 Myr. The isotopic compositions of past bottom waters were extracted from authigenic oxyhydroxide coatings of the bulk sediments. Neodymium isotope signatures obtained from surface sediments agree well with present-day deepwater ɛNd signature of -11.0 ± 0.2. Prior to 2.7 Ma the Nd and Pb isotope compositions of the bottom waters only show small variations indicative of a consistent influence of Atlantic waters. Since the major intensification of the Northern Hemisphere Glaciation at 2.7 Ma the seawater Nd isotope composition has varied more pronouncedly due to changes in weathering inputs related to the waxing and waning of the ice sheets on Svalbard, the Barents Sea, and the Eurasian shelf, due to changes in water mass exchange and due to the increasing supply of ice-rafted debris (IRD) originating from the Arctic Ocean. The seawater Pb isotope record also exhibits a higher short-term variability after 2.7 Ma, but there is also a trend toward more radiogenic values, which reflects a combination of changes in input sources and enhanced incongruent weathering inputs of Pb released from freshly eroded old continental rocks.

Documentation of programs used to determine a wetlands hydroperiod from model-simulated water-surface elevations

USGS Publications Warehouse

Sonenshein, R.S.

1996-01-01

A technique has been developed to determine a wetlands hydroperiod by comparing simulated water levels from a ground-water flow model and land- surface elevation data through a geographic information system. The simulated water levels are compared with the land-surface elevation data to determine the height of the water surface above or below land surface for the area of interest. Finally, the hydroperiod is determined for established time periods using criteria specified by the user. The program application requires the use of geographic information system software (ARC/INFO), including the TIN and GRID subsystems of the software. The application consists of an ANSI compatible C program to translate ground- water data output from the U.S. Geological Survey modular three-dimensional, finite-difference, ground-water flow model (MODFLOW) into a format that can be used as input for the geographic information system programs (AML's). The application uses ARC/INFO AML programs and ARC/INFO menu interface programs to create digital spatial data layers of the land surface and water surface and to determine the hydroperiod. The technique can be used to evaluate and manage wetlands hydrology.

Embodied energy comparison of surface water and groundwater supply options.

PubMed

Mo, Weiwei; Zhang, Qiong; Mihelcic, James R; Hokanson, David R

2011-11-01

The embodied energy associated with water provision comprises an important part of water management, and is important when considering sustainability. In this study, an input-output based hybrid analysis integrated with structural path analysis was used to develop an embodied energy model. The model was applied to a groundwater supply system (Kalamazoo, Michigan) and a surface water supply system (Tampa, Florida). The two systems evaluated have comparable total energy embodiments based on unit water production. However, the onsite energy use of the groundwater supply system is approximately 27% greater than the surface water supply system. This was primarily due to more extensive pumping requirements. On the other hand, the groundwater system uses approximately 31% less indirect energy than the surface water system, mainly because of fewer chemicals used for treatment. The results from this and other studies were also compiled to provide a relative comparison of embodied energy for major water supply options. Copyright © 2011 Elsevier Ltd. All rights reserved.

IMPEDIMENTS AND SOLUTIONS TO SUSTAINABLE, WATERSHED-SCALE URBAN STORMWATER MANAGEMENT: LESSONS FROM AUSTRALIA AND THE UNITED STATES

EPA Science Inventory

In urban and exurban areas, stormwater runoff is a primary stressor on surface waters (streams, wetlands, lakes, estuaries, and coastal waters). Conventional urban stormwater drainage systems often route runoff directly to streams and rivers, thus exacerbating pollutant inputs a...

Investigation of Carbon, Nutrients, and Groundwater Inputs in Coastal Florida Using Colored Dissolved Organic Matter

NASA Astrophysics Data System (ADS)

Arellano, A. R.; Coble, P. G.; Conmy, R. N.; Marine Spectrochemistry Group

2010-12-01

Very few studies of the exchange of water between aquifers and the ocean have been conducted along the Florida coast. Progression of residential and agricultural development in coastal areas is leading to increased nutrients from fertilizers and wastewaters to groundwater. A portion of these nutrients ultimately is released to coastal surface waters. Groundwater mining has increased salt water intrusions in coastal aquifers which may further enhance nutrient fluxes to coastal surface waters. Nutrient concentration in coastal groundwater is sometimes higher than those in river water, counterbalancing for the lower mass flux of groundwater relative to surface waters. Nutrient and carbon inputs through groundwater in certain areas may play an important role in cycling and primary productivity in the coastal ocean. King’s Bay is a spring-fed watershed and manatee sanctuary located on the West Florida Shelf. Over the past 25 years, springs supplying groundwater to King’s Bay have shown a three-fold increase in nitrate concentration and increased invasion of nuisance algae. It has been challenging to track sources of both nutrients and other water quality parameters because there are multiple water supplies to King’s Bay. The goal of this project is to improve the estimate of water, nutrients, and carbon from groundwater discharge into the coastal zone. This paper will present preliminary results of high resolution fluorescence spectroscopy analyses of the various source water types in the King's Bay watershed, including deep and shallow aquifers, wells, springs, and surface water sources. Samples were obtained from various sites--5 springs, 27 wells, 12 surface, and 9 lakes and rivers-- within the King’s Bay area during one dry season. Lakes and rivers had the highest fluorescence intensities and showed similar composition, with the most red-shifted emission maxima. Second highest concentration was seen in some of the wells which had wide range in both composition and intensities. King’s Bay surface sites appear to be a mixture of surface water and spring water based on both composition and concentration. Springs samples were all similar in composition, with concentrations in middle range found in well samples. These results will be discussed in reference to determination of source of water, carbon, and nutrients to the springs.

Contrasting nitrogen and phosphorus budgets in urban watersheds and implications for managing urban water pollution

PubMed Central

Janke, Benjamin D.; Nidzgorski, Daniel A.; Millet, Dylan B.; Baker, Lawrence A.

2017-01-01

Managing excess nutrients remains a major obstacle to improving ecosystem service benefits of urban waters. To inform more ecologically based landscape nutrient management, we compared watershed inputs, outputs, and retention for nitrogen (N) and phosphorus (P) in seven subwatersheds of the Mississippi River in St. Paul, Minnesota. Lawn fertilizer and pet waste dominated N and P inputs, respectively, underscoring the importance of household actions in influencing urban watershed nutrient budgets. Watersheds retained only 22% of net P inputs versus 80% of net N inputs (watershed area-weighted averages, where net inputs equal inputs minus biomass removal) despite relatively low P inputs. In contrast to many nonurban watersheds that exhibit high P retention, these urban watersheds have high street density that enhanced transport of P-rich materials from landscapes to stormwater. High P exports in storm drainage networks and yard waste resulted in net P losses in some watersheds. Comparisons of the N/P stoichiometry of net inputs versus storm drain exports implicated denitrification or leaching to groundwater as a likely fate for retained N. Thus, these urban watersheds exported high quantities of N and P, but via contrasting pathways: P was exported primarily via stormwater runoff, contributing to surface water degradation, whereas N losses additionally contribute to groundwater pollution. Consequently, N management and P management require different strategies, with N management focusing on reducing watershed inputs and P management also focusing on reducing P movement from vegetated landscapes to streets and storm drains. PMID:28373560

Trace Element Inputs to the Upper West Pacific from Nd Isotopes and Rare Earth Elements

NASA Astrophysics Data System (ADS)

Behrens, M. K.; Pahnke, K.; Schnetger, B.; Brumsack, H. J.

2015-12-01

Neodymium isotopes (143Nd/144Nd, expressed as ɛNd) and rare earth element (REE) concentrations in the ocean trace water mass transport and margin-seawater exchange processes. The distinct ɛNd and REE signatures of the lithogenic components of margin sediments of the West Pacific allow characterization of trace element inputs to the Pacific Ocean. We present dissolved ɛNdand REE concentrations from twelve vertical profiles of a transect from South Korea to Fiji. Near South Korea, surface waters are marked by unradiogenic ɛNd (as low as -7.3), high REE concentrations (e.g., Nd = 15.3 pmol/kg) and low salinity. Towards the open ocean, these parameters gradually change towards typical Pacific open ocean values (ɛNd = -3.3, [Nd] = 5.55 pmol/kg). Subsurface waters show REE depletions, followed by the typical REE increase with increasing water depth. These distributions indicate trace element input near South Korea and enhanced subsurface scavenging, as indicated by strong heavy REE to light REE fractionation. In the tropical West Pacific (10°N-15°S), high surface and subsurface water ɛNd values (+0.7) and positive Eu anomalies trace the influence of volcanic islands. Yet, absolute REE concentrations are extremely low at these depths (e.g., Nd = 2.77 pmol/kg). Using shale-normalized Nd/Er and Ho/Dy ratios, that show a much stronger surface to subsurface decrease in coastal waters compared to the open ocean, we suggest enhanced scavenging in this area. Eastward flowing intermediate waters (NPIW, AAIW) have ɛNd values up to +1.9 (NPIW) and +3.7 (AAIW) higher than those entering the tropical West Pacific from north and south, respectively. Modified ɛNd at intermediate depths and no change in REE patterns suggest that boundary exchange along volcanic island margins modifies the seawater ɛNd without changing the REE budget.

Water surface modeling from a single viewpoint video.

PubMed

Li, Chuan; Pickup, David; Saunders, Thomas; Cosker, Darren; Marshall, David; Hall, Peter; Willis, Philip

2013-07-01

We introduce a video-based approach for producing water surface models. Recent advances in this field output high-quality results but require dedicated capturing devices and only work in limited conditions. In contrast, our method achieves a good tradeoff between the visual quality and the production cost: It automatically produces a visually plausible animation using a single viewpoint video as the input. Our approach is based on two discoveries: first, shape from shading (SFS) is adequate to capture the appearance and dynamic behavior of the example water; second, shallow water model can be used to estimate a velocity field that produces complex surface dynamics. We will provide qualitative evaluation of our method and demonstrate its good performance across a wide range of scenes.

Microwave hydrology: A trilogy

NASA Technical Reports Server (NTRS)

Stacey, J. M.; Johnston, E. J.; Girard, M. A.; Regusters, H. A.

1985-01-01

Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest.

Inputs and internal cycling of nitrogen to a causeway influenced, hypersaline lake, Great Salt Lake, Utah, USA

USGS Publications Warehouse

Naftz, David L.

2017-01-01

Nitrogen inputs to Great Salt Lake (GSL), located in the western USA, were quantified relative to the resident nitrogen mass in order to better determine numeric nutrient criteria that may be considered at some point in the future. Total dissolved nitrogen inputs from four surface-water sources entering GSL were modeled during the 5-year study period (2010–2014) and ranged from 1.90 × 106 to 5.56 × 106 kg/year. The railroad causeway breach was a significant conduit for the export of dissolved nitrogen from Gilbert to Gunnison Bay, and in 2011 and 2012, net losses of total nitrogen mass from Gilbert Bay via the Causeway breach were 9.59 × 105 and 1.51 × 106 kg. Atmospheric deposition (wet + dry) was a significant source of nitrogen to Gilbert Bay, exceeding the dissolved nitrogen load contributed via the Farmington Bay causeway surface-water input by >100,000 kg during 2 years of the study. Closure of two railroad causeway culverts in 2012 and 2013 likely initiated a decreasing trend in the volume of the higher density Deep Brine Layer and associated declines in total dissolved nitrogen mass contained in this layer. The large dissolved nitrogen pool in Gilbert Bay relative to the amount of nitrogen contributed by surface-water inflow sources is consistent with the terminal nature of GSL and the predominance of internal nutrient cycling. The opening of the new railroad causeway breach in 2016 will likely facilitate more efficient bidirectional flow between Gilbert and Gunnison Bays, resulting in potentially substantial changes in nutrient pools within GSL.

The influence of irrigation water on the hydrology and lake water budgets of two small arid-climate lakes in Khorezm, Uzbekistan

USGS Publications Warehouse

Scott, J.; Rosen, Michael R.; Saito, L.; Decker, D.L.

2011-01-01

Little is known regarding the origins and hydrology of hundreds of small lakes located in the western Uzbekistan province of Khorezm, Central Asia. Situated in the Aral Sea Basin, Khorezm is a productive agricultural region, growing mainly cotton, wheat, and rice. Irrigation is provided by an extensive canal network that conveys water from the Amu Darya River (AD) throughout the province. The region receives on average 10 cm/year of precipitation, yet potential evapotranspiration exceeds this amount by about 15 times. It was hypothesized that the perennial existence of the lakes of interest depends on periodic input of excess irrigation water. This hypothesis was investigated by studying two small lakes in the region, Tuyrek and Khodjababa. In June and July 2008, surface water and shallow groundwater samples were collected at these lake systems and surrounding communities and analyzed for δ2H, δ18O, and major ion hydrochemistry to determine water sources. Water table and lake surface elevations were monitored, and the local aquifer characteristics were determined through aquifer tests. These data and climate data from a Class A evaporation pan and meteorological stations were used to estimate water budgets for both lakes. Lake evaporation was found to be about 0.7 cm/day during the study period. Results confirm that the waters sampled at both lake systems and throughout central Khorezm were evaporated from AD water to varying degrees. Together, the water budgets and stable isotope and major ion hydrochemistry data suggest that without surface water input from some source (i.e. excess irrigation water), these and other Khorezm lakes with similar hydrology may decrease in volume dramatically, potentially to the point of complete desiccation.

Water Quality Analysis of Yosemite Creek Watershed, San Francisco, California

NASA Astrophysics Data System (ADS)

Davis, J. R.; Snow, M. K.; Aquino, A.; Huang, C.; Thai, A.; Yuen, C.

2003-12-01

Surface water quality in urban settings can become contaminated by anthropogenic inputs. Yosemite Creek watershed is situated on the east side of San Francisco near Bayview Hunters Point and provides an ideal location for water quality investigations in urban environments. Accordingly, students from Philip and Sala Burton High School monitored water quality at three locations for their physicochemical and biological characteristics. Water was tested for pH, dissolved oxygen, conductivity, total dissolved solids, salinity, and oxidation reduction potential. In addition, a Hach DR 850 digital colorimeter was utilized to measure chlorine, fluorine, nitrogen, phosphorous, and sulfate. The biological component was assessed via monitoring benthic macro invertebrates. Specifically, the presence of caddisfly (Trichoptera) were used to indicate low levels of contaminants and good water quality. Our results indicate that water quality and macro invertebrate populations varied spatially within the watershed. Further investigation is needed to pinpoint the precise location of contaminant inputs.

Resource protection and resource management of drinking water-reservoirs in Thuringia--a prerequisite for high drinking-water quality.

PubMed

Willmitzer, H

2000-01-01

In face of widespread pollution of surface waters, strategies must be developed for the use of surface waters which protect the high quality standards of drinking water, starting with the catchment area via the reservoir to the consumer. As a rule, priority is given to the avoidance of contaminants directly at their point of origin. Water protection is always cheaper than expensive water-body restoration and water treatment. Complementary to the generally practised technical methods of raw water treatment with all their associated problems of energy input requirements, costs, and waste products, there is an increasing number of environmentally sound treatment technologies which use ecological principles as a basis to support the self-cleaning properties of flowing and dammed waters.

Factors affecting spatial and temporal variability in material exchange between the Southern Everglades wetlands and Florida Bay (USA)

NASA Astrophysics Data System (ADS)

Sutula, Martha A.; Perez, Brian C.; Reyes, Enrique; Childers, Daniel L.; Davis, Steve; Day, John W.; Rudnick, David; Sklar, Fred

2003-08-01

Physical and biological processes controlling spatial and temporal variations in material concentration and exchange between the Southern Everglades wetlands and Florida Bay were studied for 2.5 years in three of the five major creek systems draining the watershed. Daily total nitrogen (TN), and total phosphorus (TP) fluxes were measured for 2 years in Taylor River, and ten 10-day intensive studies were conducted in this creek to estimate the seasonal flux of dissolved inorganic nitrogen (N), phosphorus (P), total organic carbon (TOC), and suspended matter. Four 10-day studies were conducted simultaneously in Taylor, McCormick, and Trout Creeks to study the spatial variation in concentration and flux. The annual fluxes of TOC, TN, and TP from the Southern Everglades were estimated from regression equations. The Southern Everglades watershed, a 460-km 2 area that includes Taylor Slough and the area south of the C-111 canal, exported 7.1 g C m -2, 0.46 g N m -2, and 0.007 g P m -2, annually. Everglades P flux is three to four orders of magnitude lower than published flux estimates from wetlands influenced by terrigenous sedimentary inputs. These low P flux values reflect both the inherently low P content of Everglades surface water and the efficiency of Everglades carbonate sediments and biota in conserving and recycling this limiting nutrient. The seasonal variation of freshwater input to the watershed was responsible for major temporal variations in N, P, and C export to Florida Bay; approximately 99% of the export occurred during the rainy season. Wind-driven forcing was most important during the later stages of the dry season when low freshwater head coincided with southerly winds, resulting in a net import of water and materials into the wetlands. We also observed an east to west decrease in TN:TP ratio from 212:1 to 127:1. Major spatial gradients in N:P ratios and nutrient concentration and flux among the creek were consistent with the westward decrease in surface water runoff from the P-limited Everglades and increased advection of relatively P-rich Gulf of Mexico (GOM) waters into Florida Bay. Comparison of measured nutrient flux from Everglades surface water inputs from this study with published estimates of other sources of nutrients to Florida Bay (i.e. atmospheric deposition, anthropogenic inputs from the Florida Keys, advection from the GOM) show that Everglades runoff represents only 2% of N inputs and 0.5% of P input to Florida Bay.

A review on the sources and spatial-temporal distributions of Pb in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Zhang, Jie; Wang, Ming; Zhu, Sixi; Wu, Yunjie

2017-12-01

This paper provided a review on the source, spatial-distribution, temporal variations of Pb in Jiaozhou Bay based on investigation of Pb in surface and waters in different seasons during 1979-1983. The source strengths of Pb sources in Jiaozhou Bay were showing increasing trends, and the pollution level of Pb in this bay was slight or moderate in the early stage of reform and opening-up. Pb contents in the marine bay were mainly determined by the strength and frequency of Pb inputs from human activities, and Pb could be moving from high content areas to low content areas in the ocean interior. Surface waters in the ocean was polluted by human activities, and bottom waters was polluted by means of vertical water’s effect. The process of spatial distribution of Pb in waters was including three steps, i.e., 1), Pb was transferring to surface waters in the bay, 2) Pb was transferring to surface waters, and 3) Pb was transferring to and accumulating in bottom waters.

Analysis of Multiple Precipitation Products and Preliminary Assessment of Their Impact on Global Land Data Assimilation System (GLDAS) Land Surface States

NASA Technical Reports Server (NTRS)

Gottschalck, Jon; Meng, Jesse; Rodel, Matt; Houser, paul

2005-01-01

Land surface models (LSMs) are computer programs, similar to weather and climate prediction models, which simulate the stocks and fluxes of water (including soil moisture, snow, evaporation, and runoff) and energy (including the temperature of and sensible heat released from the soil) after they arrive on the land surface as precipitation and sunlight. It is not currently possible to measure all of the variables of interest everywhere on Earth with sufficient accuracy and space-time resolution. Hence LSMs have been developed to integrate the available observations with our understanding of the physical processes involved, using powerful computers, in order to map these stocks and fluxes as they change in time. The maps are used to improve weather forecasts, support water resources and agricultural applications, and study the Earth's water cycle and climate variability. NASA's Global Land Data Assimilation System (GLDAS) project facilitates testing of several different LSMs with a variety of input datasets (e.g., precipitation, plant type). Precipitation is arguably the most important input to LSMs. Many precipitation datasets have been produced using satellite and rain gauge observations and weather forecast models. In this study, seven different global precipitation datasets were evaluated over the United States, where dense rain gauge networks contribute to reliable precipitation maps. We then used the seven datasets as inputs to GLDAS simulations, so that we could diagnose their impacts on output stocks and fluxes of water. In terms of totals, the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) had the closest agreement with the US rain gauge dataset for all seasons except winter. The CMAP precipitation was also the most closely correlated in time with the rain gauge data during spring, fall, and winter, while the satellitebased estimates performed best in summer. The GLDAS simulations revealed that modeled soil moisture is highly sensitive to precipitation, with differences in spring and summer as large as 45% depending on the choice of precipitation input.

Groundwater, springs, and stream flow generation in an alpine meadow of a tropical glacierized catchment

NASA Astrophysics Data System (ADS)

Gordon, R.; Lautz, L. K.; McKenzie, J. M.; Mark, B. G.; Chavez, D.

2013-12-01

Melting tropical glaciers supply approximately half of dry season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows, moraines and talus slopes. A better understanding of the dynamics of alpine groundwater, including sources and contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. Our field study, conducted during the dry season in the Llanganuco valley, focused on a 0.5-km2 alpine meadow complex at 4400 m elevation, which includes talus slopes, terminal moraines, and a debris fan. Two glacial lakes and springs throughout the complex feed a network of stream channels that flow across the meadow (~2 km total length). We combined tracer measurements of stream and spring discharge and groundwater-surface water exchange with synoptic sampling of water isotopic and geochemical composition, in order to characterize and quantify contributions to streamflow from different geomorphic features. Surface water inputs to the stream channels totaled 58 l/s, while the stream gained an additional 57 l/s from groundwater inputs. Water chemistry is primarily controlled by flowpath type (surface/subsurface) and length, as well as bedrock lithology, while stable water isotopic composition appears to be controlled by water source (glacial lake, meadow or deep groundwater). Stream water chemistry is most similar to meadow groundwater springs, but isotopic composition suggests that the majority of stream water, which issues from springs at the meadow/fan interface, is from the same glacial source as the up-gradient lake. Groundwater sampled from piezometers in confined meadow aquifers is unique in both chemistry and isotopic composition, but does not contribute a large percentage of stream water exiting this small meadow, as quantified by discharge measurements and isotopic mixing. However, we expect that as streams flow down through extensive meadows and wetlands in many Cordillera Blanca valleys, meadow groundwater is a more significant contributor to streamflow. Results from this small, high meadow in Llanganuco will be compared to a larger and lower-elevation meadow system in the Quilcayhuanca valley.

The Anthropogenic Effects of Hydrocarbon Inputs to Coastal Seas: Are There Potential Biogeochemical Impacts?

NASA Astrophysics Data System (ADS)

Anderson, M. R.; Rivkin, R. B.

2016-02-01

Petroleum hydrocarbon discharges related to fossil fuel exploitation have the potential to alter microbial processes in the upper ocean. While the ecotoxicological effects of such inputs are commonly evaluated, the potential for eutrophication from the constituent organic and inorganic nutrients has been largely ignored. Hydrocarbons from natural seeps and anthropogenic sources represent a measurable source of organic carbon for surface waters. The most recent (1989-1997) estimate of average world-wide input of hydrocarbons to the sea is 1.250 x 1012 g/yr ≈ 1.0 x 1012g C/year. Produced water from offshore platforms is the largest waste stream from oil and gas exploitation and contributes significant quantities of inorganic nutrients such as N, P and Fe. In coastal areas where such inputs are a significant source of these nutrients, model studies show the potential to shift production toward smaller cells and net heterotrophy. The consequences of these nutrient sources for coastal systems and semi enclosed seas are complex and difficult to predict, because (1) there is a lack of comprehensive data on inputs and in situ concentrations and (2) the is no conceptual or quantitative framework to consider their effects on ocean biogeochemical processes. Here we use examples from the North Sea (produced water discharges 1% total riverine input and NH4 3% of the annual riverine nitrogen load), the South China Sea (total petroleum hydrocarbons = 10-1750 μg/l in offshore waters), and the Gulf of Mexico (seeps = 76-106 x 109 gC/yr, Macondo blowout 545 x 109 gC) to demonstrate how hydrocarbon and produced water inputs can influence basin scale biogeochemical and ecosystem processes and to propose a framework to consider these effects on larger scales.

MOLECULAR EVALUATION OF CHANGES IN PLANKTONIC BACTERIAL POPULATION RESULTING FROM EQUINE FECAL CONTAMINATION IN A SUB-WATERSHED

EPA Science Inventory

Contamination of watersheds by fecal bacteria is a frequent cause for surface waters to be placed on the national impaired waters list. However, since the presence of fecal bacteria does not always indicate human fecal input, it is necessary to distinguish between fecal sources. ...

Hydrology, water quality, trophic status, and aquatic plants of Fowler Lake, Wisconsin

USGS Publications Warehouse

Hughes, P.E.

1993-01-01

The low annual phosphorus input (28 pounds per square mile) to the lake from the Oconomowoc River shows the benefit of upstream lakes on the Oconomowoc River. Fourteen percent of the phosphorus input load to Fowler Lake is deposited in the lake sediments and the rest is transported through the lake by surface-water flow to downstream Lac La Belle. Dense growths of macrophytes in the lake change in composition seasonally; chara sp. (muskgrass) and Myriophyllum sp. (milfoil) are abundant in June and Najas marina and Vallesneria Americana (wild celery) are abundant in August.

Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment.

PubMed

Bergknut, Magnus; Laudon, Hjalmar; Jansson, Stina; Larsson, Anna; Gocht, Tilman; Wiberg, Karin

2011-06-01

The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hydrologic indices for nontidal wetlands

USGS Publications Warehouse

Lent, Robert M.; Weiskel, Peter K.; Lyford, Forest P.; Armstrong, David S.

1997-01-01

Two sets of hydrologic indices were developed to characterize the water-budget components of nontidal wetlands. The first set consisted of six water-budget indices for input and output variables, and the second set consisted of two hydrologic interaction indices derived from the water-budget indices. The indices then were applied to 19 wetlands with previously published water-budget data. Two trilinear diagrams for each wetland were constructed, one for the three input indices and another for the three output indices. These two trilinear diagrams then were combined with a central quadrangle to form a Piper-type diagram, with data points from the trilinear diagrams projected onto the quadrangle. The quadrangle then was divided into nine fields that summarized the water-budget information. Two quantitative "interaction indices" were calculated from two of the six water-budget indices (precipitation and evapotranspiration). They also were obtained graphically from the water-budget indices, which were first projected to the central quadrangle of a Piper-type diagram from the flanking trilinear plots. The first interaction index (l) defines the strength of interaction between a wetland and the surrounding ground- and surface-water system. The second interaction index (S) defines the nature of the interaction between the wetland and the surrounding ground- and surface-water system (source versus sink). Evaluation of these indices using published wetland water-budget data illustrates the usefulness of the technique.

Surface-water nutrient conditions and sources in the United States Pacific Northwest

USGS Publications Warehouse

Wise, D.R.; Johnson, H.M.

2011-01-01

The SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was used to perform an assessment of surface-water nutrient conditions and to identify important nutrient sources in watersheds of the Pacific Northwest region of the United States (U.S.) for the year 2002. Our models included variables representing nutrient sources as well as landscape characteristics that affect nutrient delivery to streams. Annual nutrient yields were higher in watersheds on the wetter, west side of the Cascade Range compared to watersheds on the drier, east side. High nutrient enrichment (relative to the U.S. Environmental Protection Agency's recommended nutrient criteria) was estimated in watersheds throughout the region. Forest land was generally the largest source of total nitrogen stream load and geologic material was generally the largest source of total phosphorus stream load generated within the 12,039 modeled watersheds. These results reflected the prevalence of these two natural sources and the low input from other nutrient sources across the region. However, the combined input from agriculture, point sources, and developed land, rather than natural nutrient sources, was responsible for most of the nutrient load discharged from many of the largest watersheds. Our results provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to environmental managers in future water-quality planning efforts.

Long-Term Hydrologic Impacts of Controlled Drainage Using DRAINMOD

NASA Astrophysics Data System (ADS)

Saadat, S.; Bowling, L. C.; Frankenberger, J.

2017-12-01

Controlled drainage is a management strategy designed to mitigate water quality issues caused by subsurface drainage but it may increase surface ponding and runoff. To improve controlled drainage system management, a long-term and broader study is needed that goes beyond the experimental studies. Therefore, the goal of this study was to parametrize the DRAINMOD field-scale, hydrologic model for the Davis Purdue Agricultural Center located in Eastern Indiana and to predict the subsurface drain flow and surface runoff and ponding at this research site. The Green-Ampt equation was used to characterize the infiltration, and digital elevation models (DEMs) were used to estimate the maximum depressional storage as the surface ponding parameter inputs to DRAINMOD. Hydraulic conductivity was estimated using the Hooghoudt equation and the measured drain flow and water table depths. Other model inputs were either estimated or taken from the measurements. The DRAINMOD model was calibrated and validated by comparing model predictions of subsurface drainage and water table depths with field observations from 2012 to 2016. Simulations based on the DRAINMOD model can increase understanding of the environmental and hydrological effects over a broader temporal and spatial scale than is possible using field-scale data and this is useful for developing management recommendations for water resources at field and watershed scales.

Introduction to the project DUNE, a DUst experiment in a low Nutrient, low chlorophyll Ecosystem

NASA Astrophysics Data System (ADS)

Guieu, C.; Dulac, F.; Ridame, C.; Pondaven, P.

2013-07-01

The main goal of the project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of Aeolian dust. Atmospheric deposition is now recognized as a significant source of macro- and micro-nutrients for the surface ocean, but the quantification of its role on the biological carbon pump is still poorly determined. We proposed in DUNE to investigate the role of atmospheric inputs on the functioning of an oligotrophic system particularly well adapted to this kind of study: the Mediterranean Sea. The Mediterranean Sea - etymologically, sea surrounded by land - is submitted to atmospheric inputs that are very variable both in frequency and intensity. During the thermal stratification period, only atmospheric deposition is prone to fertilize Mediterranean surface waters which has become very oligotrophic due to the nutrient depletion (after the spring bloom). This paper describes the objectives of DUNE and the implementation plan of a series of mesocosms experiments during which either wet or dry and a succession of two wet deposition fluxes of 10 g m-2 of Saharan dust have been simulated. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented, including laboratory results on the solubility of trace elements in erodible soils in addition to results from the mesocosm experiments. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension in the study of the fate of atmospheric deposition within surface waters. Results obtained can be more easily extrapolated to quantify budgets and parameterize processes such as particle migration through a "captured water column". The strong simulated dust deposition events were found to impact the dissolved concentrations of inorganic dissolved phosphorus, nitrogen, iron and other trace elements. In the case of Fe, adsorption on sinking particles yields a decrease in dissolved concentration unless binding ligands were produced following a former deposition input and associated fertilization. For the first time, a quantification of the C export induced by the aerosol addition was possible. Description and parameterization of biotic (heterotrophs and autotrophs, including diazotrophs) and abiotic processes (ballast effect due to lithogenic particles) after dust addition in sea surface water, result in a net particulate organic carbon export in part controlled by the "lithogenic carbon pump".

Deconvolution of trace element (As, Cr, Mo, Th, U) sources and pathways to surface waters of a gold mining-influenced watershed.

PubMed

Grosbois, C; Schäfer, J; Bril, H; Blanc, G; Bossy, A

2009-03-01

The Upper Isle River (SW France) drains the second most productive gold-mining district of France. A high resolution survey during one hydrological year of As, Cl(-), Cr, Fe, Mn, Mo, SO(4)(2-), Th and U dissolved concentrations in surface water aimed to better understand pathways of trace element export to the river system downstream from the mining district. Dissolved concentrations of As (up to 35000 ng/L) and Mo (up to 292 ng/L) were about 3-fold higher than the regional dissolved background and showed a negative logarithmic relation with discharge. Dissolved concentrations of Cr (up to 483 ng/L), Th (up to 48 ng/L) and U (up to 184 ng/L) increased with discharge. Geochemical relationships between molar ratios in surface water, geochemical background as well as rain- and groundwater data were combined. The contrasting behavior of distinct element groups was explained by a scenario involving three seasonal components: (i) The high flow component is poorly concentrated in As and Mo but highly concentrated in Cr, Th, U. This has been attributed to diffuse sources such as water-soil interactions, atmospheric inputs, bedrock and bed sediment weathering. Although this component probably also includes a contribution by weathering of sulfide veins, this signal is masked by dilution. (ii) One low flow component presents high SO(4)(2-), Fe, As and Mo and moderate Cr, Th and U concentrations. This component has been attributed to point sources such as mine gallery effluents, mining waste weathering and groundwater inputs from natural and/or mining-induced sulfide oxidation in the ore deposit. (iii) A second low flow component showing high As plus Mo concentrations associated with very low SO(4)(2-), Fe, Cr, Th and U concentrations, probably reflects trace element scavenging by ferric oxyhydroxide formation in the adjacent aquifer. This is supported by the decrease of Fe, Cr, Th and U in surface waters. Flux estimates suggest contrasting element-specific impacts on annual dissolved fluxes. Runoff may account for the major part of annual dissolved As, Mo, Th and U fluxes in the Upper Isle River. Inputs related to sulfide oxidation respectively contributed approximately 30% and approximately 24% to annual As and Mo fluxes. The formation of ferric oxyhydroxides strongly retained Cr, Th and U during the low flow, limiting their dissolved concentrations in surface waters. If this process may eventually decrease As mobility, its impact on dissolved As concentrations in surface water may be limited or/and counterbalanced by As release during sulfide oxidation.

The geochemistry of coprostanol in waters and surface sediments from Narragansett Bay

NASA Astrophysics Data System (ADS)

LeBlanc, Lawrence A.; Latimer, James S.; Ellis, John T.; Quinn, James G.

1992-05-01

A geochemical study of coprostanol (5β-Cholestan-3β-ol) was undertaken, to examine the transport and fate of a compound of moderate polarity and reactivity in the marine environment, and also because of the interest in coprostanol for use as a sewage tracer. During 1985-86, 20 sites in Narragansett Bay, including the major point sources and rivers discharging into the bay estuary, were sampled at four different times. In addition, surface sediments from 26 stations in the bay were collected. The large number and diversity of samples allowed for an assessment of major inputs of sewage into the bay as well as the recent fate of sewage-derived particles in surface sediments. Results from the study revealed that 50% of the total particulate coprostanol entering the bay was discharged into the Providence River, primarily due to inputs from the wastewater treatment facility (WWTF) at Fields Point, as well as input from the Pawtuxet and Blackstone Rivers. In the lower bay, the Newport WWTF was the largest single source of coprostanol (37% of the total particulate coprostanol) to the bay. Effluent concentrations of coprostanol from secondary WWTFs were consistently lower than those of primary treatment facilities, demonstrating the usefulness of corporstanol as an indicator of treatment plant efficiency. The distribution of coprostanol in waters and surface sediments showed a gradient of decreasing concentration downbay. When coprostanol concentrations in surface sediments were normalized to organic carbon (OC) concentrations, elevated levels were seen only in the Providence River, with a more or less even distribution throughout the rest of the bay. Results also suggest that coprostanol degrades more rapidly in the water column compared to the petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), however, it is relatively stable once it is buried in the sediments. Coprostanol concentrations in waters (0·02-0·22 μg 1 -1) and surface sediments (0·22-33 μg g -1) were as high or higher than values reported in the literature, indicating that the estuary is impacted by sewage.

Scaling Observations of Surface Waves in the Beaufort Sea

DTIC Science & Technology

2016-04-14

the treatment of wind input can be improved in partial ice cover using the ice concentration, where wave energy is a function of open water distance...drifting buoys during the 2014 open water season, are interpreted using open water distances determined from satellite ice products and wind forcing time...series measured in situ with the buoys. A significant portion of the wave observations were found to be limited by open water distance (fetch) when

Estimation of groundwater and nutrient fluxes to the Neuse River estuary, North Carolina

USGS Publications Warehouse

Spruill, T.B.; Bratton, J.F.

2008-01-01

A study was conducted between April 2004 and September 2005 to estimate groundwater and nutrient discharge to the Neuse River estuary in North Carolina. The largest groundwater fluxes were observed to occur generally within 20 m of the shoreline. Groundwater flux estimates based on seepage meter measurements ranged from 2.86??108 to 4.33??108 m3 annually and are comparable to estimates made using radon, a simple water-budget method, and estimates derived by using Darcy's Law and previously published general aquifer characteristics of the area. The lower groundwater flux estimate (equal to about 9 m3 s-1), which assumed the narrowest groundwater discharge zone (20 m) of three zone widths selected for an area west of New Bern, North Carolina, most closely agrees with groundwater flux estimates made using radon (3-9 m3 s-1) and Darcy's Law (about 9 m3 s-1). A groundwater flux of 9 m 3 s-1 is about 40% of the surface-water flow to the Neuse River estuary between Streets Ferry and the mouth of the estuary and about 7% of the surface-water inflow from areas upstream. Estimates of annual nitrogen (333 tonnes) and phosphorus (66 tonnes) fluxes from groundwater to the estuary, based on this analysis, are less than 6% of the nitrogen and phosphorus inputs derived from all sources (excluding oceanic inputs), and approximately 8% of the nitrogen and 17% of the phosphorus annual inputs from surface-water inflow to the Neuse River estuary assuming a mean annual precipitation of 1.27 m. We provide quantitative evidence, derived from three methods, that the contribution of water and nutrients from groundwater discharge to the Neuse River estuary is relatively minor, particularly compared with upstream sources of water and nutrients and with bottom sediment sources of nutrients. Locally high groundwater discharges do occur, however, and could help explain the occurrence of localized phytoplankton blooms, submerged aquatic vegetation, or fish kills. 

Thermodynamic and experimental study on heat transfer mechanism of miniature loop heat pipe with water-copper nanofluid

NASA Astrophysics Data System (ADS)

Wang, Xiao-wu; Wan, Zhen-ping; Tang, Yong

2018-02-01

A miniature loop heat pipe (mLHP) is a promising device for heat dissipation of electronic products. Experimental study of heat transfer performance of an mLHP employing Cu-water nanofluid as working fluid was conducted. It is found that, when input power is above 25 W, the temperature differences between the evaporator wall and vapor of nanofluid, Te - Tv, and the total heat resistance of mLHP using nanofluid are always lower than those of mLHP using de-ionized water. The values of Te - Tv and total heat resistance of mLHP using nanofluid with concentration 1.5 wt. % are the lowest, while when the input power is 25 W, the values of Te - Tv and total heat resistance of mLHP using de-ionized water are even lower than those of mLHP using nanofluid with concentration 2.0 wt. %. At larger input power, the dominant interaction is collision between small bubbles and nanoparticles which can facilitate heat transfer. While at lower input power, nanoparticles adhere to the surface of large bubble. This does not benefit boiling heat transfer. For mLHP using nanofluid with larger concentration, for example 2.0%, the heat transfer may even be worse compared with using de-ionized water at lower input power. The special structure of the mLHP in this study, two separated chambers in the evaporator, produces an extra pressure difference and contributes to the heat transfer performance of the mLHP.

Detection of variable groundwater inflow in rivers with geochemical tracers: Using major ion chemistry and radiochemistry to evaluate radon 222Rn as possible tracer, an example from the Avon and Mitchell rivers, southeast Australia

NASA Astrophysics Data System (ADS)

Hofmann, H.; Cartwright, I.

2010-12-01

Surface water-groundwater interactions are an important part of the hydrological cycle from ecological and resource perspectives. The dynamics have implications for ecosystems, pollutant transport, and the quality and quantity of water supply for domestic use, agriculture and recreational purposes. Chemical tracers are a valuable tool for understanding the interaction of rivers and the surrounding groundwater. The Gippsland Basin is a significant agricultural area in Southeast Australia. Increasing population has resulted in increased demand of water resources for domestic and agricultural supply. Despite the fact that the Gippsland area receives substantial rainfall, irrigation is still necessary to maintain agricultural production during summer and drier years. The used water resources encompass mostly shallow groundwater and surface water (reservoirs and streams). The effect on the environment range from rising water levels and soil salinisation in the case of irrigation and falling water levels with subsequent necrotization of the vegetation and land subsidence in the case of communal and industrial water extraction. While the surface water components of the hydrological cycle are relatively well understood, groundwater has often been neglected. In particular, constraining the interaction between surface water and groundwater is required for sustainable water management. Gaining and loosing conditions in streams are subject to high temporal and spatial variability and hence, influence the amount of water accessible for agricultural purposes. Following a general assumption recharge to the aquifer occurs during the winter and spring month whereas the river receives water from the aquifer mainly during low flow (base flow) conditions in summer and autumn on a larger scale. Spatial variation, however, are a function of the hydraulic conductivity of the riverbed and the head differences between the aquifer and the river along the river banks. Infiltration and exfiltration rates from changing water levels in the river based on hydraulic models are often underestimated. The hydraulic models do not take into account the complexity of the system and are purely based on discharge figures. Radon (222Rn), stable isotopes and major ion chemistry were used to locate groundwater inputs to the Mitchell and Avon rivers. While stable isotopes and major ion chemistry are useful tracers to determine long-term variability, radon can be used to detect very localised groundwater discharge. Using hydrogeochemistry to locate and quantify groundwater discharge to rivers allows a more accurate assumption on the dynamics of the interaction between surface water and groundwater in the Gippsland area. Radon has been used in similar applications elsewhere. Input parameters for mass balance equations, however, were often approximated and averaged. Radioisotope concentrations in groundwater has been assessed from 20 bores and 5 soil profiles to deliver a more confidential groundwater input water radon concentration by assessing spatial variability and emanation potential of the above-mentioned elements.

Computer program for simulation of variable recharge with the U. S. Geological Survey modular finite-difference ground-water flow model (MODFLOW)

USGS Publications Warehouse

Kontis, A.L.

2001-01-01

The Variable-Recharge Package is a computerized method designed for use with the U.S. Geological Survey three-dimensional finitedifference ground-water flow model (MODFLOW-88) to simulate areal recharge to an aquifer. It is suitable for simulations of aquifers in which the relation between ground-water levels and land surface can affect the amount and distribution of recharge. The method is based on the premise that recharge to an aquifer cannot occur where the water level is at or above land surface. Consequently, recharge will vary spatially in simulations in which the Variable- Recharge Package is applied, if the water levels are sufficiently high. The input data required by the program for each model cell that can potentially receive recharge includes the average land-surface elevation and a quantity termed ?water available for recharge,? which is equal to precipitation minus evapotranspiration. The Variable-Recharge Package also can be used to simulate recharge to a valley-fill aquifer in which the valley fill and the adjoining uplands are explicitly simulated. Valley-fill aquifers, which are the most common type of aquifer in the glaciated northeastern United States, receive much of their recharge from upland sources as channeled and(or) unchanneled surface runoff and as lateral ground-water flow. Surface runoff in the uplands is generated in the model when the applied water available for recharge is rejected because simulated water levels are at or above land surface. The surface runoff can be distributed to other parts of the model by (1) applying the amount of the surface runoff that flows to upland streams (channeled runoff) to explicitly simulated streams that flow onto the valley floor, and(or) (2) applying the amount that flows downslope toward the valley- fill aquifer (unchanneled runoff) to specified model cells, typically those near the valley wall. An example model of an idealized valley- fill aquifer is presented to demonstrate application of the method and the type of information that can be derived from its use. Documentation of the Variable-Recharge Package is provided in the appendixes and includes listings of model code and of program variables. Comment statements in the program listings provide a narrative of the code. Input-data instructions and printed model output for the package are included.

Nutrient budgets, marsh inundation under sea-level rise scenarios, and sediment chronologies for the Bass Harbor Marsh estuary at Acadia National Park

USGS Publications Warehouse

Huntington, Thomas G.; Culbertson, Charles W.; Fuller, Christopher C.; Glibert, Patricia; Sturtevant, Luke

2014-01-01

Eutrophication in the Bass Harbor Marsh estuary on Mount Desert Island, Maine, is an ongoing problem manifested by recurring annual blooms of green macroalgae species, principally Enteromorpha prolifera and Enteromorpha flexuosa, blooms that appear in the spring and summer. These blooms are unsightly and impair the otherwise natural beauty of this estuarine ecosystem. The macroalgae also threaten the integrity of the estuary and its inherent functions. The U.S. Geological Survey and Acadia National Park have collaborated for several years to better understand the factors related to this eutrophication problem with support from the U.S. Geological Survey and National Park Service Water Quality Assessment and Monitoring Program. The current study involved the collection of hydrologic and water-quality data necessary to investigate the relative contribution of nutrients from oceanic and terrestrial sources during summer 2011 and summer 2012. This report provides data on nutrient budgets for this estuary, sedimentation chronologies for the estuary and fringing marsh, and estuary bathymetry. The report also includes data, based on aerial photographs, on historical changes from 1944 to 2010 in estuary surface area and data, based on surface-elevation details, on changes in marsh area that may accompany sea-level rise. The LOADEST regression model was used to calculate nutrient loads into and out of the estuary during summer 2011 and summer 2012. During these summers, tidal inputs of ammonium to the estuary were more than seven times greater than the combined inputs in watershed runoff and precipitation. In 2011 tidal inputs of nitrate were about four times greater than watershed plus precipitation inputs, and in 2012 tidal inputs were only slightly larger than watershed plus precipitation inputs. In 2011, tidal inputs of total organic nitrogen were larger than watershed input by a factor of 1.6. By contrast, in 2012 inputs of total organic nitrogen in watershed runoff were much larger than tidal inputs, by a factor of 3.6. During the 2011 and 2012 summers, tidal inputs of total dissolved phosphorus to the estuary were more than seven times greater than inputs in watershed runoff. It is evident that during the summer tidal inputs of inorganic nitrogen and total dissolved phosphorus to the estuary exceed inputs from watershed runoff and precipitation. Projected sea-level rise associated with ongoing climate warming will affect the area of land within the Bass Harbor Marsh estuary watershed that is inundated during conditions of mean higher high water and during mean lower low water and hence will affect the vegetation and marsh area. Given 100-centimeter sea-level rise, the inundated area would increase from 25.7 hectares at the current condition to 77.5 hectares at mean higher high water and from 21.6 hectares to 26.7 hectares at mean lower low water. Given 50-centimeter sea-level rise, flooding of the entire marsh surface, which currently occurs only under the highest spring tides, would occur on average every other day. Radioisotope analysis of sediment cores from the estuary indicates that the sediment accumulation rate increased markedly from 1930 to 1980 and was relatively constant (0.4 to 0.5 centimeter per year) from 1980 to 2009. Similarly, from 1980 to 2009 there was a consistently high mass accumulation rate of 0.09 to 0.11 grams per square centimeter per year. The sediment accretion rates determined for the five cores collected from the marsh surface (east and west sides of the estuary) in 2011 show generally higher rates of 0.20 to 0.29 centimeter per year for the period between 1980 to 2011 than for the period before 1980, when sediment accretion rates were 0.06 to 0.25 centimeter per year. The data in this report provide resource managers at Acadia National Park with a baseline that can be used to evaluate future conditions within the estuary. Climate change, sea-level rise, and land-use change within the estuary’s watershed may influence nutrient dynamics, sedimentation, and eutrophication, and these potential effects can be studied in relation to the baseline data provided in this report. The Route 102 Bridge in Tremont, Maine is constructed over a sill that controls the amount of tidal flushing by restricting the duration of the flood tide, and structural changes to the bridge could alter tidal nutrient inputs and residence times for watershed and ocean-derived nutrients in the estuary. Ongoing sea-level rise is likely increasing ocean-derived nutrients and their residence time in the estuary on the one hand and decreasing the residence time of watershed-derived nutrients on the other.

Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota

NASA Astrophysics Data System (ADS)

Tfaily, Malak M.; Wilson, Rachel M.; Cooper, William T.; Kostka, Joel E.; Hanson, Paul; Chanton, Jeffrey P.

2018-02-01

We characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur, and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and excitation-emission matrix parallel factor analysis components within the peat column. In particular, the intermediate depth zone ( 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputs from surface vegetation. The intermediate depth zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal-derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively, these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table, redox oscillation, and pore water advection.

Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota: Pore Water DOM composition in a peat bog

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tfaily, Malak M.; Wilson, Rachel M.; Cooper, William T.

We characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and EEM-PARAFAC components within the peat column. In particular the intermediate depth zone (~ 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputs from surface vegetation. The intermediate-depthmore » zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds (PAC) that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal-derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate-depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table and redox oscillation and porewater advection.« less

Rare earth element distributions in the West Pacific: Trace element sources and conservative vs. non-conservative behavior

NASA Astrophysics Data System (ADS)

Behrens, Melanie K.; Pahnke, Katharina; Paffrath, Ronja; Schnetger, Bernhard; Brumsack, Hans-Jürgen

2018-03-01

Recent studies suggest that transport and water mass mixing may play a dominant role in controlling the distribution of dissolved rare earth element concentrations ([REE]) at least in parts of the North and South Atlantic and the Pacific Southern Ocean. Here we report vertically and spatially high-resolution profiles of dissolved REE concentrations ([REE]) along a NW-SE transect in the West Pacific and examine the processes affecting the [REE] distributions in this area. Surface water REE patterns reveal sources of trace element (TE) input near South Korea and in the tropical equatorial West Pacific. Positive europium anomalies and middle REE enrichments in surface and subsurface waters are indicative of TE input from volcanic islands and fingerprint in detail small-scale equatorial zonal eastward transport of TEs to the iron-limited tropical East Pacific. The low [REE] of North and South Pacific Tropical Waters and Antarctic Intermediate Water are a long-range (i.e., preformed) laterally advected signal, whereas increasing [REE] with depth within North Pacific Intermediate Water result from release from particles. Optimum multiparameter analysis of deep to bottom waters indicates a dominant control of lateral transport and mixing on [REE] at the depth of Lower Circumpolar Deep Water (≥3000 m water depth; ∼75-100% explained by water mass mixing), allowing the northward tracing of LCDW to ∼28°N in the Northwest Pacific. In contrast, scavenging in the hydrothermal plumes of the Lau Basin and Tonga-Fiji area at 1500-2000 m water depth leads to [REE] deficits (∼40-60% removal) and marked REE fractionation in the tropical West Pacific. Overall, our data provide evidence for active trace element input both near South Korea and Papua New Guinea, and for a strong lateral transport component in the distribution of dissolved REEs in large parts of the West Pacific.

Wetlands inform how climate extremes influence surface water expansion and contraction

NASA Astrophysics Data System (ADS)

Vanderhoof, Melanie K.; Lane, Charles R.; McManus, Michael G.; Alexander, Laurie C.; Christensen, Jay R.

2018-03-01

Effective monitoring and prediction of flood and drought events requires an improved understanding of how and why surface water expansion and contraction in response to climate varies across space. This paper sought to (1) quantify how interannual patterns of surface water expansion and contraction vary spatially across the Prairie Pothole Region (PPR) and adjacent Northern Prairie (NP) in the United States, and (2) explore how landscape characteristics influence the relationship between climate inputs and surface water dynamics. Due to differences in glacial history, the PPR and NP show distinct patterns in regards to drainage development and wetland density, together providing a diversity of conditions to examine surface water dynamics. We used Landsat imagery to characterize variability in surface water extent across 11 Landsat path/rows representing the PPR and NP (images spanned 1985-2015). The PPR not only experienced a 2.6-fold greater surface water extent under median conditions relative to the NP, but also showed a 3.4-fold greater change in surface water extent between drought and deluge conditions. The relationship between surface water extent and accumulated water availability (precipitation minus potential evapotranspiration) was quantified per watershed and statistically related to variables representing hydrology-related landscape characteristics (e.g., infiltration capacity, surface storage capacity, stream density). To investigate the influence stream connectivity has on the rate at which surface water leaves a given location, we modeled stream-connected and stream-disconnected surface water separately. Stream-connected surface water showed a greater expansion with wetter climatic conditions in landscapes with greater total wetland area, but lower total wetland density. Disconnected surface water showed a greater expansion with wetter climatic conditions in landscapes with higher wetland density, lower infiltration and less anthropogenic drainage. From these findings, we can expect that shifts in precipitation and evaporative demand will have uneven effects on surface water quantity. Accurate predictions regarding the effect of climate change on surface water quantity will require consideration of hydrology-related landscape characteristics including wetland storage and arrangement.

Groundwater and surface-water utilisation using a bank infiltration technique in Malaysia

NASA Astrophysics Data System (ADS)

Shamsuddin, Mohd Khairul Nizar; Sulaiman, Wan Nor Azmin; Suratman, Saim; Zakaria, Mohamad Pauzi; Samuding, Kamarudin

2014-05-01

Bank infiltration (BI) is one of the solutions to providing raw water for public supply in tropical countries. This study in Malaysia explores the use of BI to supplement a polluted surface-water resource with groundwater. Three major factors were investigated: (1) contribution of surface water through BI to the resulting abstraction, (2) input of local groundwater, and (3) water-quality characteristics of the resulting water supply. A geophysical method was employed to define the subsurface geology and hydrogeology, and isotope techniques were performed to identify the source of groundwater recharge and the interaction between surface water and groundwater. The physicochemical and microbiological parameters of the local surface-water bodies and groundwater were analyzed before and during water abstraction. Extracted water revealed a 5-98 % decrease in turbidity, as well as reductions in HCO3 -, Cl-, SO4 2-, NO3 -, Ca2+, Al3+ and As concentrations compared with those of Langat River water. In addition, amounts of E. coli, total coliform and Giardia were significantly reduced (99.9 %). However, water samples from test wells during pumping showed high concentrations of Fe2+ and Mn2+. Pumping test results indicate that the two wells used in the study were able to sustain yields.

A Nitrogen Inventory of Major Water Regions Across the USA as a Benchmark for Future Progress in Mitigating Nitrogen Pollution

NASA Astrophysics Data System (ADS)

Boyer, E. W.; Galloway, J. N.; Alexander, R. B.

2012-12-01

We present a contemporary inventory of reactive nitrogen (Nr) inputs and, air, and surface waters throughout major water regions in the United States. Inputs of Nr to the nation and the world have been increasing, largely due to human activities associated with food production and energy consumption via the combustion of fossil fuels and biofuels. Despite the obvious essential benefits of a plentiful supply of food and energy, the adverse consequences associated with the accumulation of Nr in the environment are large. Most of the Nr created by anthropogenic activities is released to the environment, often with unintended negative consequences. The greater the inputs of Nr to the landscape, the greater the potential for negative effects, caused by greenhouse gas production, ground level ozone, acid deposition, and Nr overload that can contribute to climate change, degradation of soils and vegetation, acidification of surface waters, coastal eutrophication, hypoxia and habitat loss. Here, we present a consistent accounting method for quantifying Nr sources and transport that was used in our inventory, and discuss associated data needs for tallying Nr inputs at regional scales. The inventory is a necessary tool for exploring the role of Nr contributed to the environment from various sources (e.g., from fertilizers, manure, biological fixation, human waste, atmospheric deposition) and from various industrial sectors (e.g., from agriculture, transportation, electricity generation). Agriculture and use of fertilizers to produce food, feed, and fiber (including bioenergy and biological nitrogen fixation) and combustion of fossil fuels are the largest sources of Nr released into the environment in the USA. Our inventory can be used as a benchmark of the current Nr situation against which future progress can be assessed in varying regions of the country, amidst changing Nr inputs and implementation of policy and management strategies to mitigate Nr pollution.

Barium as a potential indicator of phosphorus in agricultural runoff.

PubMed

Ahlgren, Joakim; Djodjic, Faruk; Wallin, Mats

2012-01-01

In many catchments, anthropogenic input of contaminants, and in particular phosphorus (P), into surface water is a mixture of agricultural and sewage runoff. Knowledge about the relative contribution from each of these sources is vital for mitigation of major environmental problems such as eutrophication. In this study, we investigated whether the distribution of trace elements in surface waters can be used to trace the contamination source. Water from three groups of streams was investigated: streams influenced only by agricultural runoff, streams influenced mainly by sewage runoff, and reference streams. Samples were collected at different flow regimes and times of year and analyzed for 62 elements using ICP-MS. Our results show that there are significant differences between the anthropogenic sources affecting the streams in terms of total element composition and individual elements, indicating that the method has the potential to trace anthropogenic impact on surface waters. The elements that show significant differences between sources are strontium (p < 0.001), calcium (p < 0.004), potassium (p < 0.001), magnesium (p < 0.001), boron (p < 0.001), rhodium (p = 0.001), and barium (p < 0.001). According to this study, barium shows the greatest potential as a tracer for an individual source of anthropogenic input to surface waters. We observed a strong relationship between barium and total P in the investigated samples (R(2) = 0.78), which could potentially be used to apportion anthropogenic sources of P and thereby facilitate targeting of mitigation practices. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Methane fluxes from tropical coastal lagoons surrounded bymangroves, Yucatán, Mexico

USGS Publications Warehouse

Chuang, Pei-Chuan; Young, Megan B.; Dale, Andrew W.; Miller, Laurence G.; Herrera-Silveira, Jorge A; Paytan, Adina

2017-01-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m−2 d−1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Methane fluxes from tropical coastal lagoons surrounded by mangroves, Yucatán, Mexico

NASA Astrophysics Data System (ADS)

Chuang, P.-C.; Young, M. B.; Dale, A. W.; Miller, L. G.; Herrera-Silveira, J. A.; Paytan, A.

2017-05-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m-2 d-1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Numerical analysis of one-dimensional temperature data for groundwater/surface-water exchange with 1DTempPro

NASA Astrophysics Data System (ADS)

Voytek, E. B.; Drenkelfuss, A.; Day-Lewis, F. D.; Healy, R. W.; Lane, J. W.; Werkema, D. D.

2012-12-01

Temperature is a naturally occurring tracer, which can be exploited to infer the movement of water through the vadose and saturated zones, as well as the exchange of water between aquifers and surface-water bodies, such as estuaries, lakes, and streams. One-dimensional (1D) vertical temperature profiles commonly show thermal amplitude attenuation and increasing phase lag of diurnal or seasonal temperature variations with propagation into the subsurface. This behavior is described by the heat-transport equation (i.e., the convection-conduction-dispersion equation), which can be solved analytically in 1D under certain simplifying assumptions (e.g., sinusoidal or steady-state boundary conditions and homogeneous hydraulic and thermal properties). Analysis of 1D temperature profiles using analytical models provides estimates of vertical groundwater/surface-water exchange. The utility of these estimates can be diminished when the model assumptions are violated, as is common in field applications. Alternatively, analysis of 1D temperature profiles using numerical models allows for consideration of more complex and realistic boundary conditions. However, such analyses commonly require model calibration and the development of input files for finite-difference or finite-element codes. To address the calibration and input file requirements, a new computer program, 1DTempPro, is presented that facilitates numerical analysis of vertical 1D temperature profiles. 1DTempPro is a graphical user interface (GUI) to the USGS code VS2DH, which numerically solves the flow- and heat-transport equations. Pre- and post-processor features within 1DTempPro allow the user to calibrate VS2DH models to estimate groundwater/surface-water exchange and hydraulic conductivity in cases where hydraulic head is known. This approach improves groundwater/ surface-water exchange-rate estimates for real-world data with complexities ill-suited for examination with analytical methods. Additionally, the code allows for time-varying temperature and hydraulic boundary conditions. Here, we present the approach and include examples for several datasets from stream/aquifer systems.

Modeling Input Errors to Improve Uncertainty Estimates for Sediment Transport Model Predictions

NASA Astrophysics Data System (ADS)

Jung, J. Y.; Niemann, J. D.; Greimann, B. P.

2016-12-01

Bayesian methods using Markov chain Monte Carlo algorithms have recently been applied to sediment transport models to assess the uncertainty in the model predictions due to the parameter values. Unfortunately, the existing approaches can only attribute overall uncertainty to the parameters. This limitation is critical because no model can produce accurate forecasts if forced with inaccurate input data, even if the model is well founded in physical theory. In this research, an existing Bayesian method is modified to consider the potential errors in input data during the uncertainty evaluation process. The input error is modeled using Gaussian distributions, and the means and standard deviations are treated as uncertain parameters. The proposed approach is tested by coupling it to the Sedimentation and River Hydraulics - One Dimension (SRH-1D) model and simulating a 23-km reach of the Tachia River in Taiwan. The Wu equation in SRH-1D is used for computing the transport capacity for a bed material load of non-cohesive material. Three types of input data are considered uncertain: (1) the input flowrate at the upstream boundary, (2) the water surface elevation at the downstream boundary, and (3) the water surface elevation at a hydraulic structure in the middle of the reach. The benefits of modeling the input errors in the uncertainty analysis are evaluated by comparing the accuracy of the most likely forecast and the coverage of the observed data by the credible intervals to those of the existing method. The results indicate that the internal boundary condition has the largest uncertainty among those considered. Overall, the uncertainty estimates from the new method are notably different from those of the existing method for both the calibration and forecast periods.

Effects of climate change on evapotranspiration over the Okavango Delta water resources

NASA Astrophysics Data System (ADS)

Moses, Oliver; Hambira, Wame L.

2018-06-01

In semi-arid developing countries, most poor people depend on contaminated surface or groundwater resources since they do not have access to safe and centrally supplied water. These water resources are threatened by several factors that include high evapotranspiration rates. In the Okavango Delta region in the north-western Botswana, communities facing insufficient centrally supplied water rely mainly on the surface water resources of the Delta. The Delta loses about 98% of its water through evapotranspiration. However, the 2% remaining water rescues the communities facing insufficient water from the main stream water supply. To understand the effects of climate change on evapotranspiration over the Okavango Delta water resources, this study analysed trends in the main climatic parameters needed as input variables in evapotranspiration models. The Mann Kendall test was used in the analysis. Trend analysis is crucial since it reveals the direction of trends in the climatic parameters, which is helpful in determining the effects of climate change on evapotranspiration. The main climatic parameters required as input variables in evapotranspiration models that were of interest in this study were wind speeds, solar radiation and relative humidity. Very little research has been conducted on these climatic parameters in the Okavango Delta region. The conducted trend analysis was more on wind speeds, which had relatively longer data records than the other two climatic parameters of interest. Generally, statistically significant increasing trends have been found, which suggests that climate change is likely to further increase evapotranspiration over the Okavango Delta water resources.

Estimation of missing water-level data for the Everglades Depth Estimation Network (EDEN), 2013 update

USGS Publications Warehouse

Petkewich, Matthew D.; Conrads, Paul

2013-01-01

The Everglades Depth Estimation Network is an integrated network of real-time water-level gaging stations, a ground-elevation model, and a water-surface elevation model designed to provide scientists, engineers, and water-resource managers with water-level and water-depth information (1991-2013) for the entire freshwater portion of the Greater Everglades. The U.S. Geological Survey Greater Everglades Priority Ecosystems Science provides support for the Everglades Depth Estimation Network in order for the Network to provide quality-assured monitoring data for the U.S. Army Corps of Engineers Comprehensive Everglades Restoration Plan. In a previous study, water-level estimation equations were developed to fill in missing data to increase the accuracy of the daily water-surface elevation model. During this study, those equations were updated because of the addition and removal of water-level gaging stations, the consistent use of water-level data relative to the North American Vertical Datum of 1988, and availability of recent data (March 1, 2006, to September 30, 2011). Up to three linear regression equations were developed for each station by using three different input stations to minimize the occurrences of missing data for an input station. Of the 667 water-level estimation equations developed to fill missing data at 223 stations, more than 72 percent of the equations have coefficients of determination greater than 0.90, and 97 percent have coefficients of determination greater than 0.70.

Solute Response To Arid-Climate Managed-River Flow During Storm Events

NASA Astrophysics Data System (ADS)

McLean, B.; Shock, E.

2006-12-01

Storm pulses are widely used in unmanaged, temperate and subtropical river systems to resolve in-stream surface and subsurface flow components. Resulting catchment-scale hydrochemical mixing models yield insight into mechanisms of solute transport. Managed systems are far more complicated due to the human need for high quality water resources, which drives processes that are superimposed on most, if not all, of the unmanaged components. As an example, an increasingly large portion of the water supply for the Phoenix metropolitan area is derived from multiple surface water sources that are impounded, diverted and otherwise managed upstream from the urban core that consumes the water and produces anthropogenic impacts. During large storm events this managed system is perturbed towards natural behavior as it receives inputs from natural hydrologic pathways in addition to impervious surfaces and storm water drainage channels. Our goals in studying managed river systems during this critical transition state are to determine how the well- characterized behavior of natural systems break down as the system responds then returns to its managed state. Using storm events as perturbations we can contrast an arid managed system with the unmanaged system it approaches during the storm event. In the process, we can extract geochemical consequences specifically related to unknown urban components in the form of chemical fingerprints. The effects of river management on solute behavior were assessed by taking advantage of several anomalously heavy winter storm events in late 2004 and early 2005 using a rigorous sampling routine. Several hundred samples collected between January and October 2005 were analyzed for major ion, isotopic, and trace metal concentrations with 78 individual measurements for each sample. The data are used to resolve managed watershed processes, mechanisms of solute transport and river mixing from anthropogenic inputs. Our results show that concentrations of major solutes change slowly and are independent of discharge downstream from the dams on two major tributaries. This is indicative of reservoir release water. In addition, a third input is derived from the Colorado River via the Central Arizona Project canal system. Cross plots including concentrations of solutes such as nitrate and sulfate from downstream of the confluence indicate at least three end-member sources, as do Piper diagrams using major anion and cation data. Dynamic contributions from natural event water and urban inputs can be resolved from the slowly changing release water, and may dictate the short-term transport of pollutants during the storm-induced transition state.

Effects of farmhouse hotel and paper mill effluents on bacterial community structures in sediment and surface water of Nanxi River, China.

PubMed

Lu, Xiao-Ming; Lu, Peng-Zhen

2014-11-01

The pyrosequencing technique was used to evaluate bacterial community structures in sediment and surface water samples taken from Nanxi River receiving effluents from a paper mill and a farmhouse hotel, respectively. For each sample, 4,610 effective bacterial sequences were selected and used to do the analysis of diversity and abundance, respectively. Bacterial phylotype richness in the sediment sample without effluent input was higher than the other samples, and the surface water sample with addition of effluent from the paper mill contained the least richness. Effluents from both the paper mill and farmhouse hotel have a potential to reduce the bacterial diversity and abundance in the sediment and surface water, especially it is more significant in the sediment. The effect of the paper mill effluent on the sediment and surface water bacterial communities was more serious than that of the farmhouse hotel effluent. Characterization of microbial community structures in the sediment and surface water from two tributaries of the downstream river indicated that various effluents from the paper mill and farmhouse hotel have the similar potential to decrease the natural variability in riverine microbial ecosystems.

High resolution production water footprints of the United States

NASA Astrophysics Data System (ADS)

Marston, L.; Yufei, A.; Konar, M.; Mekonnen, M.; Hoekstra, A. Y.

2017-12-01

The United States is the largest producer and consumer of goods and services in the world. Rainfall, surface water supplies, and groundwater aquifers represent a fundamental input to this economic production. Despite the importance of water resources to economic activity, we do not have consistent information on water use for specific locations and economic sectors. A national, high-resolution database of water use by sector would provide insight into US utilization and dependence on water resources for economic production. To this end, we calculate the water footprint of over 500 food, energy, mining, services, and manufacturing industries and goods produced in the US. To do this, we employ a data intensive approach that integrates water footprint and input-output techniques into a novel methodological framework. This approach enables us to present the most detailed and comprehensive water footprint analysis of any country to date. This study broadly contributes to our understanding of water in the US economy, enables supply chain managers to assess direct and indirect water dependencies, and provides opportunities to reduce water use through benchmarking.

Surface water polycyclic aromatic hydrocarbons (PAH) in urban areas of Nanjing, China.

PubMed

Wang, Chunhui; Zhou, Shenglu; Wu, Shaohua; Song, Jing; Shi, Yaxing; Li, Baojie; Chen, Hao

2017-10-01

The concentration, sources and environmental risks of polycyclic aromatic hydrocarbons (PAHs) in surface water in urban areas of Nanjing were investigated. The range of ∑ 16 PAHs concentration is between 4,076 and 29,455 ng/L, with a mean of 17,212 ng/L. The composition of PAHs indicated that 2- and 3-ring PAHs have the highest proportion in all PAHs, while the 5- and 6-ring PAHs were the least in proportion. By diagnostic ratio analysis, combustion and petroleum were a mixture input that contributed to the water PAH in urban areas of Nanjing. Positive matrix factorization quantitatively identified four factors, including coke oven, coal combustion, oil source, and vehicle emission, as the main sources. Toxic equivalency factors of BaP (BaP eq ) evaluate the environmental risks of PAHs and indicate the PAH concentration in surface water in urban areas of Nanjing had been polluted and might cause potential environmental risks. Therefore, the PAH contamination in surface water in urban areas of Nanjing should draw considerable attention.

Water fluxes and diffuse nitrate pollution at river basin scale: coupling of agro-economic models and hydrological approaches.

PubMed

Wendland, F; Kunkel, R; Bogena, H; Gömann, H; Kreins, P

2007-01-01

An integrated model system has been developed to estimate the impact of nitrogen reduction measures on the nitrogen load in groundwater and in river catchment areas. The focus lies on an area-wide, regionally differentiated, consistent link-up between the indicator "nitrogen balance surplus" and nitrogen charges into surface waters. As a starting point of the analysis actual nitrogen surpluses in the soil were quantified using the agro-economic RAUMIS-model, which considers the most important N-inputs to the soil and N-removals from the soil through crop harvest. The most important pathways for diffuse nitrogen inputs into river systems are modelled with the water balance model GROWA. Additionally, the time-dependent nitrogen degradation along the nitrogen pathways in soil and groundwater are modelled using the WEKU-model. The two selected river basins in Germany cover a variety of landscape units with different hydrological, hydrogeological and socio-economic characteristics. The results indicate a wide range of annual nitrogen surpluses for the rural areas between than 10 kg N ha(-1) x a(-1) and 200 kg N ha(-1) x a(-1) or more, depending on the type and intensity of farming. The level of nitrogen inputs into the surface waters is reduced because of degradation processes during transport in soil and groundwater. Policy impact analyses for a nitrogen tax and a limitation of the livestock density stress the importance of regionally adjusted measures.

Stereoscopic Feature Tracking System for Retrieving Velocity of Surface Waters

NASA Astrophysics Data System (ADS)

Zuniga Zamalloa, C. C.; Landry, B. J.

2017-12-01

The present work is concerned with the surface velocity retrieval of flows using a stereoscopic setup and finding the correspondence in the images via feature tracking (FT). The feature tracking provides a key benefit of substantially reducing the level of user input. In contrast to other commonly used methods (e.g., normalized cross-correlation), FT does not require the user to prescribe interrogation window sizes and removes the need for masking when specularities are present. The results of the current FT methodology are comparable to those obtained via Large Scale Particle Image Velocimetry while requiring little to no user input which allowed for rapid, automated processing of imagery.

Theory for source-responsive and free-surface film modeling of unsaturated flow

USGS Publications Warehouse

Nimmo, J.R.

2010-01-01

A new model explicitly incorporates the possibility of rapid response, across significant distance, to substantial water input. It is useful for unsaturated flow processes that are not inherently diffusive, or that do not progress through a series of equilibrium states. The term source-responsive is used to mean that flow responds sensitively to changing conditions at the source of water input (e.g., rainfall, irrigation, or ponded infiltration). The domain of preferential flow can be conceptualized as laminar flow in free-surface films along the walls of pores. These films may be considered to have uniform thickness, as suggested by field evidence that preferential flow moves at an approximately uniform rate when generated by a continuous and ample water supply. An effective facial area per unit volume quantitatively characterizes the medium with respect to source-responsive flow. A flow-intensity factor dependent on conditions within the medium represents the amount of source-responsive flow at a given time and position. Laminar flow theory provides relations for the velocity and thickness of flowing source-responsive films. Combination with the Darcy-Buckingham law and the continuity equation leads to expressions for both fluxes and dynamic water contents. Where preferential flow is sometimes or always significant, the interactive combination of source-responsive and diffuse flow has the potential to improve prediction of unsaturated-zone fluxes in response to hydraulic inputs and the evolving distribution of soil moisture. Examples for which this approach is efficient and physically plausible include (i) rainstorm-generated rapid fluctuations of a deep water table and (ii) space- and time-dependent soil water content response to infiltration in a macroporous soil. ?? Soil Science Society of America.

Impact of anthropogenic atmospheric nitrogen and sulfur deposition on ocean acidification and the inorganic carbon system.

PubMed

Doney, Scott C; Mahowald, Natalie; Lima, Ivan; Feely, Richard A; Mackenzie, Fred T; Lamarque, Jean-Francois; Rasch, Phil J

2007-09-11

Fossil fuel combustion and agriculture result in atmospheric deposition of 0.8 Tmol/yr reactive sulfur and 2.7 Tmol/yr nitrogen to the coastal and open ocean near major source regions in North America, Europe, and South and East Asia. Atmospheric inputs of dissociation products of strong acids (HNO(3) and H2SO(4)) and bases (NH(3)) alter surface seawater alkalinity, pH, and inorganic carbon storage. We quantify the biogeochemical impacts by using atmosphere and ocean models. The direct acid/base flux to the ocean is predominately acidic (reducing total alkalinity) in the temperate Northern Hemisphere and alkaline in the tropics because of ammonia inputs. However, because most of the excess ammonia is nitrified to nitrate (NO(3)(-)) in the upper ocean, the effective net atmospheric input is acidic almost everywhere. The decrease in surface alkalinity drives a net air-sea efflux of CO(2), reducing surface dissolved inorganic carbon (DIC); the alkalinity and DIC changes mostly offset each other, and the decline in surface pH is small. Additional impacts arise from nitrogen fertilization, leading to elevated primary production and biological DIC drawdown that reverses in some places the sign of the surface pH and air-sea CO(2) flux perturbations. On a global scale, the alterations in surface water chemistry from anthropogenic nitrogen and sulfur deposition are a few percent of the acidification and DIC increases due to the oceanic uptake of anthropogenic CO(2). However, the impacts are more substantial in coastal waters, where the ecosystem responses to ocean acidification could have the most severe implications for mankind.

Climate and the equilibrium state of land surface hydrology parameterizations

NASA Technical Reports Server (NTRS)

Entekhabi, Dara; Eagleson, Peter S.

1991-01-01

For given climatic rates of precipitation and potential evaporation, the land surface hydrology parameterizations of atmospheric general circulation models will maintain soil-water storage conditions that balance the moisture input and output. The surface relative soil saturation for such climatic conditions serves as a measure of the land surface parameterization state under a given forcing. The equilibrium value of this variable for alternate parameterizations of land surface hydrology are determined as a function of climate and the sensitivity of the surface to shifts and changes in climatic forcing are estimated.

Towards a Near Real-Time Satellite-Based Flux Monitoring System for the MENA Region

NASA Astrophysics Data System (ADS)

Ershadi, A.; Houborg, R.; McCabe, M. F.; Anderson, M. C.; Hain, C.

2013-12-01

Satellite remote sensing has the potential to offer spatially and temporally distributed information on land surface characteristics, which may be used as inputs and constraints for estimating land surface fluxes of carbon, water and energy. Enhanced satellite-based monitoring systems for aiding local water resource assessments and agricultural management activities are particularly needed for the Middle East and North Africa (MENA) region. The MENA region is an area characterized by limited fresh water resources, an often inefficient use of these, and relatively poor in-situ monitoring as a result of sparse meteorological observations. To address these issues, an integrated modeling approach for near real-time monitoring of land surface states and fluxes at fine spatio-temporal scales over the MENA region is presented. This approach is based on synergistic application of multiple sensors and wavebands in the visible to shortwave infrared and thermal infrared (TIR) domain. The multi-scale flux mapping and monitoring system uses the Atmosphere-Land Exchange Inverse (ALEXI) model and associated flux disaggregation scheme (DisALEXI), and the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) in conjunction with model reanalysis data and multi-sensor remotely sensed data from polar orbiting (e.g. Landsat and MODerate resolution Imaging Spectroradiometer (MODIS)) and geostationary (MSG; Meteosat Second Generation) satellite platforms to facilitate time-continuous (i.e. daily) estimates of field-scale water, energy and carbon fluxes. Within this modeling system, TIR satellite data provide information about the sub-surface moisture status and plant stress, obviating the need for precipitation input and a detailed soil surface characterization (i.e. for prognostic modeling of soil transport processes). The STARFM fusion methodology blends aspects of high frequency (spatially coarse) and spatially fine resolution sensors and is applied directly to flux output fields to facilitate daily mapping of fluxes at sub-field scales. A complete processing infrastructure to automatically ingest and pre-process all required input data and to execute the integrated modeling system for near real-time agricultural monitoring purposes over targeted MENA sites is being developed, and initial results from this concerted effort will be discussed.

Analysis of heavy metal sources in storm water from urban areas

NASA Astrophysics Data System (ADS)

Scherer, U.; Fuchs, S.

2009-04-01

The input of heavy metals into surface waters is a serious impairment of the aquatic environment. The emissions of heavy metals via point and diffuse pathways into the German river basins were thus quantified for the period of 1985 through 2005. The total emission into the German river systems decreased for each metal during the observed period. This reduction is mainly caused by the decline of emissions via point sources. The measures taken by industry and implemented within the scope of a stringently water legislation have decisively contributed to an improvement of environmental conditions. Today's emissions of heavy metals into river basins of Germany are dominated by the input via diffuse pathways. One of the most important diffuse input is the storm water discharged from paved urban areas into the surface waters via storm sewers and combined sewer overflows especially for the metals copper, zinc and lead. The objective of this project was to identify the sources of these three heavy metals washed of from paved urban areas. The use of copper, zinc and lead on the outsides of buildings results in emissions to water and soil via rainwater due to weathering and runoff of soluble and insoluble metallic compounds. Copper and zinc are traditionally used materials in the building sector especially for roofs, gutters and facades. Lead, in contrast, plays only a subordinate role due to its more limited outdoor use. The corrosion rates vary widely. Climatic factors (temperature, humidity etc.), above all the presence of corrosive gases (sulphur dioxide, nitrogen oxide, ozone etc.) influence the corrosion processes. Estimates of industrial associations were referred to in order to determine the corrosion relevant metal surfaces. Heavy metal emissions caused by traffic are complex and depend on many parameters which vary by locality, time and substance. In principle, substances can be emitted by vehicles, the road surface and by maintenance. Emissions of copper, lead and zinc are mainly caused by wear and tear of tyres and brake pads. The reference figures of the environmental emissions are usually the kilometres driven per vehicle. The emissions can then be calculated based on the road performance. Furthermore atmospheric deposition on paved urban areas was considered. The heavy metal emission from each individual source and the portion discharged into surface waters via storm sewers and combined sewer overflows was quantified. The emission sum of all sources was validated using emission data of storm sewers based on measured heavy metal concentrations and the discharge volume showing a good agreement.

The Influence of Topography on Subaqueous Sediment Gravity Flows and the Resultant Deposits: Examples from Deep-water Systems in Offshore Morocco and Offshore Trinidad

NASA Astrophysics Data System (ADS)

Deng, H.; Wood, L.; Overeem, I.; Hutton, E.

2016-12-01

Submarine topography has a fundamental control on the movement of sediment gravity flows as well as the distribution, morphology, and internal heterogeneity of resultant overlying, healing-phase, deep-water reservoirs. Some of the most complex deep-water topography is generated through both destructive and constructive mass transport processes. A series of numerical models using Sedflux software have been constructed over high resolution mass transport complexes (MTCs) top paleobathymetric surfaces mapped from 3D seismic data in offshore Morocco and offshore eastern Trinidad. Morocco's margin is characterized by large, extant rafted blocks and a flow perpendicular fabric. Trinidad's margin is characterized by muddier, plastic flows and isolated extrusive diapiric buttresses. In addition, Morocco's margin is a dry, northern latitude margin that lacks major river inputs, while Trinidad's margin is an equatorial, wet climate that is fed by the Orinoco River and delta. These models quantitatively delineate the interaction of healing-phase gravity flows on the tops of two very different topographies and provide insights into healing-phase reservoir distribution and stratigraphic trap development. Slopes roughness, curvatures, and surface shapes are measured and quantified relative to input points to quantify depositional surface character. A variety of sediment gravity flow types have been input and the resultant interval assessed for thickness and distribution relative to key topography parameters. Mathematical relationships are to be analyzed and compared with seismic data interpretation of healing-phase interval character, toward an improved model of gravity sedimentation and topography interactions.

ESA's Soil Moisture dnd Ocean Salinity Mission - Contributing to Water Resource Management

NASA Astrophysics Data System (ADS)

Mecklenburg, S.; Kerr, Y. H.

2015-12-01

The Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, is the European Space Agency's (ESA) second Earth Explorer Opportunity mission. The scientific objectives of the SMOS mission directly respond to the need for global observations of soil moisture and ocean salinity, two key variables used in predictive hydrological, oceanographic and atmospheric models. SMOS observations also provide information on the characterisation of ice and snow covered surfaces and the sea ice effect on ocean-atmosphere heat fluxes and dynamics, which affects large-scale processes of the Earth's climate system. The focus of this paper will be on SMOS's contribution to support water resource management: SMOS surface soil moisture provides the input to derive root-zone soil moisture, which in turn provides the input for the drought index, an important monitoring prediction tool for plant available water. In addition to surface soil moisture, SMOS also provides observations on vegetation optical depth. Both parameters aid agricultural applications such as crop growth, yield forecasting and drought monitoring, and provide input for carbon and land surface modelling. SMOS data products are used in data assimilation and forecasting systems. Over land, assimilating SMOS derived information has shown to have a positive impact on applications such as NWP, stream flow forecasting and the analysis of net ecosystem exchange. Over ocean, both sea surface salinity and severe wind speed have the potential to increase the predictive skill on the seasonal and short- to medium-range forecast range. Operational users in particular in Numerical Weather Prediction and operational hydrology have put forward a requirement for soil moisture data to be available in near-real time (NRT). This has been addressed by developing a fast retrieval for a NRT level 2 soil moisture product based on Neural Networks, which will be available by autumn 2015. This paper will focus on presenting the above applications and used SMOS data products.

Input dynamics of pesticide transformation products into surface water

NASA Astrophysics Data System (ADS)

Kern, Susanne; Singer, Heinz; Hollender, Juliane; Schwarzenbach, René P.; Fenner, Kathrin

2010-05-01

Some pesticide transformation products have been observed to occur in higher concentrations and more frequently than the parent active pesticide in surface water and groundwater. These products are often more mobile and sometimes more stable than the parent pesticide. If they also represent the major product into which the parent substance is transformed, these transformation products may dominate observed pesticide occurrences in surface water and groundwater. Their potential contribution to the overall risk to the aquatic environment caused by the use of the parent pesticide should therefore not be neglected in chemical risk and water quality assessments. The same is true for transformation products of other compound classes that might reach the soil environment, such as veterinary pharmaceuticals. However, the fate and input pathways of transformation products of soil-applied chemicals into surface water are not yet well understood, which largely prevents their appropriate inclusion into chemical risk and water quality assessments. Here, we studied whether prioritization methods based on available environmental fate data from pesticide registration dossiers in combination with basic fate models could help identify transformation products which can be found in relevant concentrations in surface and groundwater and which should therefore be included into monitoring programs. A three-box steady state model containing air, soil, and surface water compartments was used to predict relative inputs of pesticide transformation products into surface waters based on their physico-chemical and environmental fate properties. The model predictions were compared to monitoring data from a small Swiss river located in an intensely agricultural catchment (90 km2) which was flow-proportionally sampled from May to October 2008 and screened for 74 pesticides as well as 50 corresponding transformation products. Sampling mainly occurred during high discharge, but additional samples during baseflow conditions were also taken. The analytical measurements included solid phase extraction, liquid chromatography and high resolution mass spectrometry (SPE-LC-HR-MS/MS). Quantification was achieved using reference standards and internal standards. Besides the well-known transformation products of triazine and chloroacetanilide herbicides, transformation products of other compound classes such as azoxystrobin acid (from azoxystrobin, strobilurin fungicide), chloridazon-desphenyl and chloridazon-methyl-desphenyl (from chloridazon, pyridazinone herbicide), and metamitron-desamino (from metamitron, triazinone herbicide) were analyzed in surface water. For a selection of widely used pesticides in the catchment, modelled ratios of transformation product versus parent pesticide concentrations were compared to the measured concentration ratios in the river for the application period and for two 2-month periods following application. Concentration ratios agreed within a factor of 10 for all pairs of parent pesticides and transformation products, and for all seasons, with a single exception. The ratio of chloridazon-desphenyl to chloridazon was under-predicted by a factor of approximately 20. The data revealed that chloridazon-desphenyl was also found in elevated concentrations in all baseflow samples, indicating its presence in the groundwater component of the catchment. The same was true for other transformation products (e.g., metamitron-desamino, chloridazon-methly-desphenyl, metolachlor-ESA), but to a lesser degree. Based on baseflow separation of the hydrograph, the concentration ratio estimation model was supplemented with an additional baseflow component. The concentrations in the baseflow component were estimated with a simple leaching relationship that was compared against measured baseflow concentrations and groundwater findings in Switzerland. The final model yielded good agreement for all compounds and is therefore deemed suitable for prioritization of transformation products with a relevant exposure potential. It also clearly indicated the contribution of groundwater to the overall occurrence of pesticides and their transformation products in Swiss surface waters.

In-lake carbon dioxide concentration patterns in four distinct phases in relation to ice cover dynamics

NASA Astrophysics Data System (ADS)

Denfeld, B. A.; Wallin, M.; Sahlee, E.; Sobek, S.; Kokic, J.; Chmiel, H.; Weyhenmeyer, G. A.

2014-12-01

Global carbon dioxide (CO2) emission estimates from inland waters include emissions at ice melt that are based on simple assumptions rather than evidence. To account for CO2 accumulation below ice and potential emissions into the atmosphere at ice melt we combined continuous CO2 concentrations with spatial CO2 sampling in an ice-covered small boreal lake. From early ice cover to ice melt, our continuous surface water CO2 concentration measurements at 2 m depth showed a temporal development in four distinct phases: In early winter, CO2 accumulated continuously below ice, most likely due to biological in-lake and catchment inputs. Thereafter, in late winter, CO2 concentrations remained rather constant below ice, as catchment inputs were minimized and vertical mixing of hypolimnetic water was cut off. As ice melt began, surface water CO2 concentrations were rapidly changing, showing two distinct peaks, the first one reflecting horizontal mixing of CO2 from surface and catchment waters, the second one reflecting deep water mixing. We detected that 83% of the CO2 accumulated in the water during ice cover left the lake at ice melt which corresponded to one third of the total CO2 storage. Our results imply that CO2 emissions at ice melt must be accurately integrated into annual CO2 emission estimates from inland waters. If up-scaling approaches assume that CO2 accumulates linearly under ice and at ice melt all CO2 accumulated during ice cover period leaves the lake again, present estimates may overestimate CO2 emissions from small ice covered lakes. Likewise, neglecting CO2 spring outbursts will result in an underestimation of CO2 emissions from small ice covered lakes.

Surface-Water Nutrient Conditions and Sources in the United States Pacific Northwest1

PubMed Central

Wise, Daniel R; Johnson, Henry M

2011-01-01

Abstract The SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was used to perform an assessment of surface-water nutrient conditions and to identify important nutrient sources in watersheds of the Pacific Northwest region of the United States (U.S.) for the year 2002. Our models included variables representing nutrient sources as well as landscape characteristics that affect nutrient delivery to streams. Annual nutrient yields were higher in watersheds on the wetter, west side of the Cascade Range compared to watersheds on the drier, east side. High nutrient enrichment (relative to the U.S. Environmental Protection Agency's recommended nutrient criteria) was estimated in watersheds throughout the region. Forest land was generally the largest source of total nitrogen stream load and geologic material was generally the largest source of total phosphorus stream load generated within the 12,039 modeled watersheds. These results reflected the prevalence of these two natural sources and the low input from other nutrient sources across the region. However, the combined input from agriculture, point sources, and developed land, rather than natural nutrient sources, was responsible for most of the nutrient load discharged from many of the largest watersheds. Our results provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to environmental managers in future water-quality planning efforts. PMID:22457584

Effects of near-surface hydraulic gradients on nitrate and phosphorus losses in surface runoff.

PubMed

Zheng, Fen-Li; Huang, Chi-Hua; Norton, L Darrell

2004-01-01

Phosphorous (P) and nitrogen (N) in runoff from agricultural fields are key components of nonpoint-source pollution and can accelerate eutrophication of surface waters. A laboratory study was designed to evaluate effects of near-surface hydraulic gradients on P and N losses in surface runoff from soil pans at 5% slope under simulated rainfall. Experimental treatments included three rates of fertilizer input (control [no fertilizer input], low [40 kg P ha(-1), 100 kg N ha(-1)], and high [80 kg P ha(-1), 200 kg N ha(-1)]) and four near-surface hydraulic gradients (free drainage [FD], saturation [Sa], artesian seepage without rain [Sp], and artesian seepage with rain [Sp + R]). Simulated rainfall of 50 mm h(-1) was applied for 90 min. The results showed that near-surface hydraulic gradients have dramatic effects on NO(3)-N and PO(4)-P losses and runoff water quality. Under the low fertilizer treatment, the average concentrations in surface runoff from FD, Sa, Sp, and Sp + R were 0.08, 2.20, 529.5, and 71.8 mg L(-1) for NO(3)-N and 0.11, 0.54, 0.91, and 0.72 mg L(-1) for PO(4)-P, respectively. Similar trends were observed for the concentrations of NO(3)-N and PO(4)-P under the high fertilizer treatment. The total NO(3)-N loss under the FD treatment was only 0.01% of the applied nitrogen, while under the Sp and Sp + R treatments, the total NO(3)-N loss was 11 to 16% of the applied nitrogen. These results show that artesian seepage could make a significant contribution to water quality problems.

Harmful freshwater algal blooms, with an emphasis on cyanobacteria.

PubMed

Paerl, H W; Fulton, R S; Moisander, P H; Dyble, J

2001-04-04

Suspended algae, or phytoplankton, are the prime source of organic matter supporting food webs in freshwater ecosystems. Phytoplankton productivity is reliant on adequate nutrient supplies; however, increasing rates of nutrient supply, much of it manmade, fuels accelerating primary production or eutrophication. An obvious and problematic symptom of eutrophication is rapid growth and accumulations of phytoplankton, leading to discoloration of affected waters. These events are termed blooms. Blooms are a prime agent of water quality deterioration, including foul odors and tastes, deoxygenation of bottom waters (hypoxia and anoxia), toxicity, fish kills, and food web alterations. Toxins produced by blooms can adversely affect animal (including human) health in waters used for recreational and drinking purposes. Numerous freshwater genera within the diverse phyla comprising the phytoplankton are capable of forming blooms; however, the blue-green algae (or cyanobacteria) are the most notorious bloom formers. This is especially true for harmful toxic, surface-dwelling, scum-forming genera (e.g., Anabaena, Aphanizomenon, Nodularia, Microcystis) and some subsurface bloom-formers (Cylindrospermopsis, Oscillatoria) that are adept at exploiting nutrient-enriched conditions. They thrive in highly productive waters by being able to rapidly migrate between radiance-rich surface waters and nutrient-rich bottom waters. Furthermore, many harmful species are tolerant of extreme environmental conditions, including very high light levels, high temperatures, various degrees of desiccation, and periodic nutrient deprivation. Some of the most noxious cyanobacterial bloom genera (e.g., Anabaena, Aphanizomenon, Cylindrospermopsis, Nodularia) are capable of fixing atmospheric nitrogen (N2), enabling them to periodically dominate under nitrogen-limited conditions. Cyanobacteria produce a range of organic compounds, including those that are toxic to higher-ranked consumers, from zooplankton to further up the food chain. Both N2- and non-N2-fixing genera participate in mutualistic and symbiotic associations with microorganisms, higher plants, and animals. These associations appear to be of great benefit to their survival and periodic dominance. In this review, we address the ecological impacts and environmental controls of harmful blooms, with an emphasis on the ecology, physiology, and management of cyanobacterial bloom taxa. Combinations of physical, chemical, and biotic features of natural waters function in a synergistic fashion to determine the sensitivity of water bodies. In waters susceptible to blooms, human activities in water- and airsheds have been linked to the extent and magnitudes of blooms. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on nitrogen (N) and/or phosphorus (P). The types and amount of nutrient input constraints depend on hydrologic, climatic, geographic, and geologic factors, which interact with anthropogenic and natural nutrient input regimes. While single nutrient input constraints may be effective in some water bodies, dual N and P input reductions are usually required for effective long-term control and management of harmful blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by enhanced flushing and artificial mixing (in conjunction with nutrient input constraints) can be particularly effective alternatives. Implications of various management strategies, based on combined ecophysiological and environmental considerations, are discussed.

Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands.

PubMed

Baken, Stijn; Degryse, Fien; Verheyen, Liesbeth; Merckx, Roel; Smolders, Erik

2011-04-01

Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R2=0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.

Groundwater Contributions to Intermittent Streamflow in a Headwater Catchment: How do Geoclimatic Controls Influence Downstream Water Quality?

NASA Astrophysics Data System (ADS)

Smull, E. M.; Gooseff, M. N.; Singha, K.

2014-12-01

Hydrologic connectivity of headwater catchments affects surface water yield and quality of downstream drinking water supplies. Lower Gordon Gulch, a 2.75 km2 catchment, is part of the Boulder Creek watershed - the primary drinking water supply for the city of Boulder, Colorado. We hypothesize that the geologic and climatic environment within the catchment controls the magnitude, timing, and duration of hydrologic connection between the landscape and the stream, and thus the distribution of major ions to the surface water. Specifically, bedrock patterns, vegetation type and density, and snowpack dynamics influence how precipitation inputs move from the hillslopes to the catchment outlet. Preliminary results suggest that north-facing hillslopes with steeper slopes, deeper weathering of bedrock, denser vegetation stands, and a seasonal snowpack, provide consistently greater groundwater inputs to the stream compared to the south-facing hillslopes. We believe that this is in part due to subsurface bedrock patterns forcing a dominate cross-valley gradient. Through an extensive observation network of hillslope wells, periodic stream water balance measurements, and synoptic chemistry samples, we plan to continue our assessment of the spatio-temporal connectivity dynamics throughout the seasonal dry down (late summer through winter), during which streamflow can be intermittent. Results will help to guide landuse practices of upland catchments with respect to their role in Boulder's drinking water supply.

EXPERIMENTAL EVALUATION OF THE THERMAL PERFORMANCE OF A WATER SHIELD FOR A SURFACE POWER REACTOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

REID, ROBERT S.; PEARSON, J. BOSIE; STEWART, ERIC T.

2007-01-16

Water based reactor shielding is being investigated for use on initial lunar surface power systems. A water shield may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a 100 kWt lunar surface reactor shield design is evaluated with 2 kW power input to the water in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WSTmore » is used to validate a CFD model. Performance of the water shield on the lunar surface is then predicted with a CFD model anchored to test data. The experiment had a maximum water temperature of 75 C. The CFD model with 1/6-g predicts a maximum water temperature of 88 C with the same heat load and external boundary conditions. This difference in maximum temperature does not greatly affect the structural design of the shield, and demonstrates that it may be possible to use water for a lunar reactor shield.« less

Improvements to water use and water stress estimates with the addition of IR and net radiometers to weather stations

USDA-ARS?s Scientific Manuscript database

Evapotranspiration (ET) is often estimated with the Penman-Monteith (P-M) equation. Net radiation (Rn) is a major component of the surface energy balance and an input to the P-M equation, but it is challenging and expensive to measure accurately. For these reasons, most weather stations do not inclu...

Linking land use changes to surface water quality variability in Lake Victoria: some insights from remote sensing

NASA Astrophysics Data System (ADS)

Mugo, R. M.; Limaye, A. S.; Nyaga, J. W.; Farah, H.; Wahome, A.; Flores, A.

2016-12-01

The water quality of inland lakes is largely influenced by land use and land cover changes within the lake's catchment. In Africa, some of the major land use changes are driven by a number of factors, which include urbanization, intensification of agricultural practices, unsustainable farm management practices, deforestation, land fragmentation and degradation. Often, the impacts of these factors are observable on changes in the land cover, and eventually in the hydrological systems. When the natural vegetation cover is reduced or changed, the surface water flow patterns, water and nutrient retention capacities are also changed. This can lead to high nutrient inputs into lakes, leading to eutrophication, siltation and infestation of floating aquatic vegetation. To assess the relationship between land use and land cover changes in part of the Lake Victoria Basin, a series of land cover maps were derived from Landsat imagery. Changes in land cover were identified through change maps and statistics. Further, the surface water chlorophyll-a concentration and turbidity were derived from MODIS-Aqua data for Lake Victoria. Chlrophyll-a and turbidity are good proxy indicators of nutrient inputs and siltation respectively. The trends in chlorophyll-a and turbidity concentrations were analyzed and compared to the land cover changes over time. Certain land cover changes related to agriculture and urban development were clearly identifiable. While these changes might not be solely responsible for variability in chlrophyll-a and turbidity concentrations in the lake, they are potentially contributing factors to this problem. This work illustrates the importance of addressing watershed degradation while seeking to solve water quality related problems.

Indicating anthropogenic effectson urban water system - indicators and extension

NASA Astrophysics Data System (ADS)

Strauch, G.; Ufz-Team

2003-04-01

Urban water systems are polluted by diffusive and direct contribution of anthropogenic activities. Besides industrial contaminants like aromatic and chlorinated HC and other persistent organic compounds, the urban aquatic environment is increasingly polluted by low concentrated but high eco-toxic compounds as pharmaceuticals, fragrances, plasticizers which most have disrupt endocrine functions, and trace elements carried in by surface and sub-surface waste water and seeping processes. This contamination could have a longtime impact on the urban ecosystem and on the human health. The interdisciplinary project on risk assessment of water pollution was initiated to explore new methodologies for assessing human activities on the urban water system and processes among urban watersheds. In a first assumption we used a flow model concept with in- and output and surface water transport represented by the city of Halle, Germany, and the river Saale. The river Saale acts as surface water system collecting waste water inputs along the city traverse. We investigated the anthropogenic effect on the urban water system using the indicators hydrological parameters, compound specific pattern of complex organic substances and trace elements, isotopic signatures of water (H, O) and dissolved substances (sulfate, DIC, nitrate), pathogens, and microbiota. A first balance modeling showed that main ions are not very sensitive concerning the direct urban input into the river. Depending on the discharge of the river in high and low flood stages the load of dissolved matter has no specific urban effect. However, the concentration pattern of fragrances (tonalid, galaxolid) and endocrine disrupters (t-nonylphenol) point to a different pollution along the city traverse: downstream of the sewage plant a higher load was observed in comparison to the upstream passage. Furthermore, a degradation ability of fungi and bacteria occurred in the bank sediments could be detected in lab experiments concerning the fragrances, and endocrine disrupters (t-nonylphenol, phthalate). The Saale water samples contain components able to eco-toxic and immunomodulated effects as measured on the vitality and cytokine-secretion profile of human peripheral blood mononuclear cells (PBMC). Even fragrances caused such effects which are unknown so far. The study of assessing urban effects onto the water system is still under investigation.

Assessment of spill flow emissions on the basis of measured precipitation and waste water data

NASA Astrophysics Data System (ADS)

Hochedlinger, Martin; Gruber, Günter; Kainz, Harald

2005-09-01

Combined sewer overflows (CSOs) are substantial contributors to the total emissions into surface water bodies. The emitted pollution results from dry-weather waste water loads, surface runoff pollution and from the remobilisation of sewer deposits and sewer slime during storm events. One possibility to estimate overflow loads is a calculation with load quantification models. Input data for these models are pollution concentrations, e.g. Total Chemical Oxygen Demand (COD tot), Total Suspended Solids (TSS) or Soluble Chemical Oxygen Demand (COD sol), rainfall series and flow measurements for model calibration and validation. It is important for the result of overflow loads to model with reliable input data, otherwise this inevitably leads to bad results. In this paper the correction of precipitation measurements and the sewer online-measurements are presented to satisfy the load quantification model requirements already described. The main focus is on tipping bucket gauge measurements and their corrections. The results evidence the importance of their corrections due the effects on load quantification modelling and show the difference between corrected and not corrected data of storm events with high rain intensities.

Anthropogenic phosphorus flow analysis of Hefei City, China.

PubMed

Li, Sisi; Yuan, Zengwei; Bi, Jun; Wu, Huijun

2010-11-01

The substance flow analysis (SFA) method was employed to examine phosphorus flow and its connection to water pollution in the city of Hefei, China, in 2008. As human activity is the driving force of phosphorus flux from the environment to the economy, the study provides a conceptual framework for analyzing an anthropogenic phosphorus cycle that includes four stages: extraction, fabrication and manufacturing, use, and waste management. Estimates of phosphorus flow were based on existing data as well as field research, expert advice, local accounting systems, and literature. The total phosphorus input into Hefei in 2008 reached 7810 tons, mainly as phosphate ore, chemical fertilizer, pesticides, crops and animal products. Approximately 33% of the total phosphorus input left the area, and nearly 20% of that amount was discharged as waste to surface water. Effluent containing excessive fertilizer from farming operations plays an important role in phosphorus overloads onto surface water; the other major emission source is sewage discharge. We also provide suggestions for reducing phosphorus emissions, for example reducing fertilizer use, recycling farming residues, and changing human consumption patterns. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

[Further reduction of nitrogen fertilizer application in paddy field under green manuring of Taihu Area, China].

PubMed

Zhao, Dong; Yan, Ting-mei; Qiao, Jun; Yang, Lin-zhang; Tang, Fang; Song, Yun-fei

2015-06-01

This study focused on the nitrogen loss via runoff, change of nitrogen in different forms in surface water in paddy field, and grain yield, through further reduction of nitrogen fertilizer application rate under green manuring without basal dressing. Results showed that with 150 kg · hm(-2) inorganic N fertilizer input after return of green manure to soil, no basal dressing could not only sharply reduce N concentration in surface water and decrease 17.2% of N loss, but also increase 2.8% of grain yield in comparison with basal dressing. It was a worthwhile farming method that inorganic nitrogen fertilizer was not used for basal dressing but for topdressing after return of green ma- nure to soil in Taihu Area. However, the grain yield would decrease if the rate of topdressing nitro- gen was excessively reduced or increased. After all, it was feasible to realize harmonization of grain yield and environmental benefits in Taihu Area, with 133 kg · hm(-2) inorganic N fertilizer input after return of green manure to soil as well as no application of basal dressing, which could greatly reduce N fertilizer input and N loss as well as ensure rice yield.

Remote sensing inputs to water demand modeling

NASA Technical Reports Server (NTRS)

Estes, J. E.; Jensen, J. R.; Tinney, L. R.; Rector, M.

1975-01-01

In an attempt to determine the ability of remote sensing techniques to economically generate data required by water demand models, the Geography Remote Sensing Unit, in conjunction with the Kern County Water Agency of California, developed an analysis model. As a result it was determined that agricultural cropland inventories utilizing both high altitude photography and LANDSAT imagery can be conducted cost effectively. In addition, by using average irrigation application rates in conjunction with cropland data, estimates of agricultural water demand can be generated. However, more accurate estimates are possible if crop type, acreage, and crop specific application rates are employed. An analysis of the effect of saline-alkali soils on water demand in the study area is also examined. Finally, reference is made to the detection and delineation of water tables that are perched near the surface by semi-permeable clay layers. Soil salinity prediction, automated crop identification on a by-field basis, and a potential input to the determination of zones of equal benefit taxation are briefly touched upon.

Seasonal cycle of circulation in the Antarctic Peninsula and the off-shelf transport of shelf waters into southern Drake Passage and Scotia Sea

NASA Astrophysics Data System (ADS)

Jiang, Mingshun; Charette, Matthew A.; Measures, Christopher I.; Zhu, Yiwu; Zhou, Meng

2013-06-01

The seasonal cycle of circulation and transport in the Antarctic Peninsula shelf region is investigated using a high-resolution (˜2 km) regional model based on the Regional Oceanic Modeling System (ROMS). The model also includes a naturally occurring tracer with a strong source over the shelf (radium isotope 228Ra, t1/2=5.8 years) to investigate the sediment Fe input and its transport. The model is spun-up for three years using climatological boundary and surface forcing and then run for the 2004-2006 period using realistic forcing. Model results suggest a persistent and coherent circulation system throughout the year consisting of several major components that converge water masses from various sources toward Elephant Island. These currents are largely in geostrophic balance, driven by surface winds, topographic steering, and large-scale forcing. Strong off-shelf transport of the Fe-rich shelf waters takes place over the northeastern shelf/slope of Elephant Island, driven by a combination of topographic steering, extension of shelf currents, and strong horizontal mixing between the ACC and shelf waters. These results are generally consistent with recent and historical observational studies. Both the shelf circulation and off-shelf transport show a significant seasonality, mainly due to the seasonal changes of surface winds and large-scale circulation. Modeled and observed distributions of 228Ra suggest that a majority of Fe-rich upper layer waters exported off-shelf around Elephant Island are carried by the shelfbreak current and the Bransfield Strait Current from the shallow sills between Gerlache Strait and Livingston Island, and northern shelf of the South Shetland Islands, where strong winter mixing supplies much of the sediment derived nutrients (including Fe) input to the surface layer.

Estimating pesticide runoff in small streams.

PubMed

Schriever, Carola A; von der Ohe, Peter C; Liess, Matthias

2007-08-01

Surface runoff is one of the most important pathways for pesticides to enter surface waters. Mathematical models are employed to characterize its spatio-temporal variability within landscapes, but they must be simple owing to the limited availability and low resolution of data at this scale. This study aimed to validate a simplified spatially-explicit model that is developed for the regional scale to calculate the runoff potential (RP). The RP is a generic indicator of the magnitude of pesticide inputs into streams via runoff. The underlying runoff model considers key environmental factors affecting runoff (precipitation, topography, land use, and soil characteristics), but predicts losses of a generic substance instead of any one pesticide. We predicted and evaluated RP for 20 small streams. RP input data were extracted from governmental databases. Pesticide measurements from a triennial study were used for validation. Measured pesticide concentrations were standardized by the applied mass per catchment and the water solubility of the relevant compounds. The maximum standardized concentration per site and year (runoff loss, R(Loss)) provided a generalized measure of observed pesticide inputs into the streams. Average RP explained 75% (p<0.001) of the variance in R(Loss). Our results imply that the generic indicator can give an adequate estimate of runoff inputs into small streams, wherever data of similar resolution are available. Therefore, we suggest RP for a first quick and cost-effective location of potential runoff hot spots at the landscape level.

TRACE GAS CONCENTRATIONS IN STREAMS - EARLY WARNING INDICATORS OF STREAM IMPAIRMENT?

EPA Science Inventory

Surface water contamination and resultant impairment of aquatic ecosystem functioning are serious environmental problems, caused in large part by land use changes and excess organic waste inputs associated with agriculture and residential and industrial development. Headwater st...

Wetlands inform how climate extremes influence surface water expansion and contraction

USGS Publications Warehouse

Vanderhoof, Melanie; Lane, Charles R.; McManus, Michael L.; Alexander, Laurie C.; Christensen, Jay R.

2018-01-01

Effective monitoring and prediction of flood and drought events requires an improved understanding of how and why surface water expansion and contraction in response to climate varies across space. This paper sought to (1) quantify how interannual patterns of surface water expansion and contraction vary spatially across the Prairie Pothole Region (PPR) and adjacent Northern Prairie (NP) in the United States, and (2) explore how landscape characteristics influence the relationship between climate inputs and surface water dynamics. Due to differences in glacial history, the PPR and NP show distinct patterns in regards to drainage development and wetland density, together providing a diversity of conditions to examine surface water dynamics. We used Landsat imagery to characterize variability in surface water extent across 11 Landsat path/rows representing the PPR and NP (images spanned 1985–2015). The PPR not only experienced a 2.6-fold greater surface water extent under median conditions relative to the NP, but also showed a 3.4-fold greater change in surface water extent between drought and deluge conditions. The relationship between surface water extent and accumulated water availability (precipitation minus potential evapotranspiration) was quantified per watershed and statistically related to variables representing hydrology-related landscape characteristics (e.g., infiltration capacity, surface storage capacity, stream density). To investigate the influence stream connectivity has on the rate at which surface water leaves a given location, we modeled stream-connected and stream-disconnected surface water separately. Stream-connected surface water showed a greater expansion with wetter climatic conditions in landscapes with greater total wetland area, but lower total wetland density. Disconnected surface water showed a greater expansion with wetter climatic conditions in landscapes with higher wetland density, lower infiltration and less anthropogenic drainage. From these findings, we can expect that shifts in precipitation and evaporative demand will have uneven effects on surface water quantity. Accurate predictions regarding the effect of climate change on surface water quantity will require consideration of hydrology-related landscape characteristics including wetland storage and arrangement.

Soil aggregate stability and rainfall-induced sediment transport on field plots as affected by amendment with organic matter inputs

NASA Astrophysics Data System (ADS)

Shi, Pu; Arter, Christian; Liu, Xingyu; Keller, Martin; Schulin, Rainer

2017-04-01

Aggregate stability is an important factor in soil resistance against erosion, and, by influencing the extent of sediment transport associated with surface runoff, it is thus also one of the key factors which determine on- and off-site effects of water erosion. As it strongly depends on soil organic matter, many studies have explored how aggregate stability can be improved by organic matter inputs into the soil. However, the focus of these studies has been on the relationship between aggregate stability and soil organic matter dynamics. How the effects of organic matter inputs on aggregate stability translate into soil erodibility under rainfall impacts has received much less attention. In this study, we performed field plot experiments to examine how organic matter inputs affect aggregate breakdown and surface sediment transport under field conditions in artificial rainfall events. Three pairs of plots were prepared by adding a mixture of grass and wheat straw to one of plots in each pair but not to the other, while all plots were treated in the same way otherwise. The rainfall events were applied some weeks later so that the applied organic residues had sufficient time for decomposition and incorporation into the soil. Surface runoff rate and sediment concentration showed substantial differences between the treatments with and without organic matter inputs. The plots with organic inputs had coarser and more stable aggregates and a rougher surface than the control plots without organic inputs, resulting in a higher infiltration rate and lower transport capacity of the surface runoff. Consequently, sediments exported from the amended plots were less concentrated but more enriched in suspended particles (<20 µm) than from the un-amended plots, indicating a more size-selective sediment transport. In contrast to the amended plots, there was an increase in the coarse particle fraction (> 250 µm) in the runoff from the plots with no organic matter inputs towards the end of the rainfall events due to emerging bed-load transport. The results show that a single application of organic matter can already cause a large difference in aggregate breakdown, surface sealing, and lateral sediment-associated matter transfer under rainfall impact. Furthermore, we will present terrestrial laser scanning data showing the treatment effects on soil surface structure, as well as data on carbon, phosphorus and heavy metal export associated with the translocation of the sediments.

Not all water becomes wine: Sulfur inputs as an opportune tracer of hydrochemical losses from vineyards

USGS Publications Warehouse

Hinckley, Eve-Lyn S.; Kendall, Carol; Loague, Keith

2009-01-01

California's widespread and economically important vineyards offer substantial opportunities to understand the interface between hydrology and biogeochemistry in agricultural soils. The common use of native sulfur (S) as a fumigant or soil additive provides a novel way to isotopically differentiate among sulfate (SO42−) pools, allowing the estimation of water and SO42− budgets. The objectives of this study were (1) to characterize the near‐surface hydrological flow paths in a vineyard during irrigation and storm events and (2) to determine how those flow paths affect the fate and transport of SO42− across seasons. Integrating hydrological theory with measurements of SO42−concentration and sulfate‐S isotopic ratios (expressed as [SO42−] and δ34S, respectively) in inputs, soil water, and leachate provided a means of determining flow paths. Low [SO42−] and δ34S in leachate during 4‐h irrigation events reflect minimal engagement of the soil matrix, indicating that preferential flow was the dominant path for water in the near surface. In contrast, high [SO42−] and δ34S values during 8‐h irrigation and storm events reflect near‐complete engagement of the soil matrix, indicating that lateral flow was the dominant pathway. Because hydrologic response and SO42− mobility are tightly coupled in these soils, the magnitude of water fluxes through the near surface controls S cycling both on and off site. These results indicate that preferential flow is an important loss pathway to consider in managing both water resources and water quality (reactive elements) in vineyard land use systems.

Assessment of effectiveness of geologic isolation systems. CIRMIS data system. Volume 3. Generator routines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.; Argo, R.S.

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (ONWI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. The various input parameters required in the analysis are compiled in data systems. The data are organized and preparedmore » by various input subroutines for utilization by the hydraulic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required. The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System, a storage and retrieval system for model input and output data, including graphical interpretation and display is described. This is the third of four volumes of the description of the CIRMIS Data System.« less

Assessment of effectiveness of geologic isolation systems. CIRMIS data system. Volume 1. Initialization, operation, and documentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.

1980-01-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (ONWI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. The various input parameters required in the analysis are compiled in data systems. The data are organized and preparedmore » by various input subroutines for use by the hydrologic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required. The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System, a storage and retrieval system for model input and output data, including graphical interpretation and display is described. This is the first of four volumes of the description of the CIRMIS Data System.« less

Harmonize input selection for sediment transport prediction

NASA Astrophysics Data System (ADS)

Afan, Haitham Abdulmohsin; Keshtegar, Behrooz; Mohtar, Wan Hanna Melini Wan; El-Shafie, Ahmed

2017-09-01

In this paper, three modeling approaches using a Neural Network (NN), Response Surface Method (RSM) and response surface method basis Global Harmony Search (GHS) are applied to predict the daily time series suspended sediment load. Generally, the input variables for forecasting the suspended sediment load are manually selected based on the maximum correlations of input variables in the modeling approaches based on NN and RSM. The RSM is improved to select the input variables by using the errors terms of training data based on the GHS, namely as response surface method and global harmony search (RSM-GHS) modeling method. The second-order polynomial function with cross terms is applied to calibrate the time series suspended sediment load with three, four and five input variables in the proposed RSM-GHS. The linear, square and cross corrections of twenty input variables of antecedent values of suspended sediment load and water discharge are investigated to achieve the best predictions of the RSM based on the GHS method. The performances of the NN, RSM and proposed RSM-GHS including both accuracy and simplicity are compared through several comparative predicted and error statistics. The results illustrated that the proposed RSM-GHS is as uncomplicated as the RSM but performed better, where fewer errors and better correlation was observed (R = 0.95, MAE = 18.09 (ton/day), RMSE = 25.16 (ton/day)) compared to the ANN (R = 0.91, MAE = 20.17 (ton/day), RMSE = 33.09 (ton/day)) and RSM (R = 0.91, MAE = 20.06 (ton/day), RMSE = 31.92 (ton/day)) for all types of input variables.

Hydrological and chemical budgets in a volcanic caldera lake: Lake Kussharo, Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Chikita, Kazuhisa A.; Nishi, Masataka; Fukuyama, Ryuji; Hamahara, Kazuhiro

2004-05-01

The contribution of groundwater output and input to lake chemistry was examined by estimating the hydrological and chemical budgets of a volcanic caldera lake, Lake Kussharo, Hokkaido, Japan. The lake level, meteorology, river water discharge and water properties were measured in the ice-covered period of February-March and in the open-water period of June-October in 2000. The inorganic chemistry was then analyzed for sporadically sampled surface water and hot spring water. The chemistry of lake water at pH of 6.91-7.57 and EC25 (electric conductivity at 25 °C) of 29.2-32.7 mS/m appears to be controlled by the input of two types of hot spring water: the inflowing Yunokawa River (pH of 2.27-2.54 and EC25 of 197.8-258.0 mS/m) and groundwater discharging directly on the shore (pH of 7.13-8.32, water temperature of 35.0-46.5 °C and EC25 of 53.1-152.0 mS/m). Excluding the days with rainfall or a great change in lake level, the water budget in June-October gave a net groundwater input of -7.41 to 2.97 m 3/s. A combination of the water budget with the chemical budget of two solutes, Na + and Cl -, led to the best estimate of groundwater output, Gout, at 3.82±3.02 m 3/s, the total fresh groundwater input, ∑ Gfresh, at 2.14±1.00 m 3/s, and the total groundwater input of hot springs, ∑ Gspa, at 0.46±0.05 m 3/s. This is comparable to G out=3.87 m3/ s, ∑G fresh=1.49 m3/ s and ∑G spa=0.41 m3/ s during the ice-covered period. The chemical flux by the freshwater input plays an important role in the alkalinity of lake water, as does the chemical flux by the shoreline hot springs. The large groundwater output could occur by the leakage through the highly permeable, underground pumice, distributed from the east-to-south lake basin to southeast of the outlet.

Methodology for assessing quantities of water and proppant injection, and water production associated with development of continuous petroleum accumulations

USGS Publications Warehouse

Haines, Seth S.

2015-07-13

The quantities of water and hydraulic fracturing proppant required for producing petroleum (oil, gas, and natural gas liquids) from continuous accumulations, and the quantities of water extracted during petroleum production, can be quantitatively assessed using a probabilistic approach. The water and proppant assessment methodology builds on the U.S. Geological Survey methodology for quantitative assessment of undiscovered technically recoverable petroleum resources in continuous accumulations. The U.S. Geological Survey assessment methodology for continuous petroleum accumulations includes fundamental concepts such as geologically defined assessment units, and probabilistic input values including well-drainage area, sweet- and non-sweet-spot areas, and success ratio within the untested area of each assessment unit. In addition to petroleum-related information, required inputs for the water and proppant assessment methodology include probabilistic estimates of per-well water usage for drilling, cementing, and hydraulic-fracture stimulation; the ratio of proppant to water for hydraulic fracturing; the percentage of hydraulic fracturing water that returns to the surface as flowback; and the ratio of produced water to petroleum over the productive life of each well. Water and proppant assessments combine information from recent or current petroleum assessments with water- and proppant-related input values for the assessment unit being studied, using Monte Carlo simulation, to yield probabilistic estimates of the volume of water for drilling, cementing, and hydraulic fracture stimulation; the quantity of proppant for hydraulic fracture stimulation; and the volumes of water produced as flowback shortly after well completion, and produced over the life of the well.

Effective water surface mapping in macrophyte-covered reservoirs in NE Brazil based on TerraSAR-X time series

NASA Astrophysics Data System (ADS)

Zhang, Shuping; Foerster, Saskia; Medeiros, Pedro; de Araújo, José Carlos; Waske, Bjoern

2018-07-01

Water supplies in northeastern Brazil strongly depend on the numerous surface water reservoirs of various sizes there. However, the seasonal and long-term water surface dynamics of these reservoirs, particularly the large number of small ones, remain inadequately known. Remote sensing techniques have shown great potentials in water bodies mapping. Yet, the widespread presence of macrophytes in most of the reservoirs often impedes the delineation of the effective water surfaces. Knowledge of the dynamics of the effective water surfaces in the reservoirs is essential for understanding, managing, and modelling the local and regional water resources. In this study, a two-year time series of TerraSAR-X (TSX) satellite data was used to monitor the effective water surface areas in nine reservoirs in NE Brazil. Calm open water surfaces were obtained by segmenting the backscattering coefficients of TSX images with minimum error thresholding. Linear unmixing was implemented on the distributions of gray-level co-occurrence matrix (GLCM) variance in the reservoirs to quantify the proportions of sub-populations dominated by different types of scattering along the TSX time series. By referring to the statistics and the seasonal proportions of the GLCM variance sub-populations the GLCM variance was segmented to map the vegetated water surfaces. The effective water surface areas that include the vegetation-covered waters as well as calm open water in the reservoirs were mapped with accuracies >77%. The temporal and spatial change patterns of water surfaces in the nine reservoirs over a period of two consecutive dry and wet seasons were derived. Precipitation-related soil moisture changes, topography and the dense macrophyte canopies are the main sources of errors in the such-derived effective water surfaces. Independent from in-situ data, the approach employed in this study shows great potential in monitoring water surfaces of different complexity and macrophyte coverage. The effective water surface areas obtained for the reservoirs can provide valuable input for efficient water management and improve the hydrological modelling in this region.

Analysis of pesticides in surface water, stemflow, and throughfall in an agricultural area in South Georgia, USA.

PubMed

Glinski, Donna A; Purucker, S Thomas; Van Meter, Robin J; Black, Marsha C; Henderson, W Matthew

2018-06-18

To study spray drift contributions to non-targeted habitats, pesticide concentrations in stemflow (water flowing down the trunk of a tree during a rain event), throughfall (water from tree canopy only), and surface water in an agriculturally impacted wetland area near Tifton, Georgia, USA were measured (2015-2016). Agricultural fields and sampling locations were on the University of Georgia's Gibbs Research Farm, Tifton, GA. Samples were screened for more than 160 pesticides, and cumulatively, 32 different pesticides were detected across matrices. Data indicate that herbicides and fungicides were present in all types of environmental samples analyzed while insecticides were only detected in surface water samples. The highest pesticide concentration observed was 10.50 μg/L of metolachlor in an August 2015 surface water sample. Metolachlor, tebuconazole, and fipronil were the most frequently detected herbicide, fungicide, and insecticide, respectively, regardless of sample origin. The most frequently detected pesticide in surface water and stemflow samples was metolachlor (0.09-10.5 μg/L), however, the most commonly detected pesticide in throughfall samples was biphenyl (0.02-0.07 μg/L). These data help determine the importance of indirect chemical exposures to non-targeted habitats by assessing inputs from stemflow and throughfall into surface waters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Droplet ejection and sliding on a flapping film

NASA Astrophysics Data System (ADS)

Chen, Xi; Doughramaji, Nicole; Betz, Amy Rachel; Derby, Melanie M.

2017-03-01

Water recovery and subsequent reuse are required for human consumption as well as industrial, and agriculture applications. Moist air streams, such as cooling tower plumes and fog, represent opportunities for water harvesting. In this work, we investigate a flapping mechanism to increase droplet shedding on thin, hydrophobic films for two vibrational cases (e.g., ± 9 mm and 11 Hz; ± 2 mm and 100 Hz). Two main mechanisms removed water droplets from the flapping film: vibrational-induced coalescence/sliding and droplet ejection from the surface. Vibrations mobilized droplets on the flapping film, increasing the probability of coalescence with neighboring droplets leading to faster droplet growth. Droplet departure sizes of 1-2 mm were observed for flapping films, compared to 3-4 mm on stationary films, which solely relied on gravity for droplet removal. Additionally, flapping films exhibited lower percentage area coverage by water after a few seconds. The second removal mechanism, droplet ejection was analyzed with respect to surface wave formation and inertia. Smaller droplets (e.g., 1-mm diameter) were ejected at a higher frequency which is associated with a higher acceleration. Kinetic energy of the water was the largest contributor to energy required to flap the film, and low energy inputs (i.e., 3.3 W/m2) were possible. Additionally, self-flapping films could enable novel water collection and condensation with minimal energy input.

Assessment of groundwater input and water quality changes impacting natural vegetation in the Loxahatchee River and floodplain ecosystem, Florida

USGS Publications Warehouse

Orem, William H.; Swarzenski, Peter W.; McPherson, Benjamin F.; Hedgepath, Marion; Lerch, Harry E.; Reich, Christopher; Torres, Arturo E.; Corum, Margo D.; Roberts, Richard E.

2007-01-01

The Loxahatchee River and Estuary are small, shallow, water bodies located in southeastern Florida. Historically, the Northwest Branch (Fork) of the Loxahatchee River was primarily a freshwater system. In 1947, the river inlet at Jupiter was dredged for navigation and has remained permanently open since that time. Drainage patterns within the basin have also been altered significantly due to land development, road construction (e.g., Florida Turnpike), and construction of the C-18 and other canals. These anthropogenic activities along with sea level rise have resulted in significant adverse impacts on the ecosystem over the last several decades, including increased saltwater encroachment and undesired vegetation changes in the floodplain. The problem of saltwater intrusion and vegetation degradation in the Loxahatchee River may be partly induced by diminished freshwater input, from both surface water and ground water into the River system. The overall objective of this project was to assess the seasonal surface water and groundwater interaction and the influence of the biogeochemical characteristics of shallow groundwater and porewater on vegetation health in the Loxahatchee floodplain. The hypothesis tested are: (1) groundwater influx constitutes a significant component of the overall flow of water into the Loxahatchee River; (2) salinity and other chemical constituents in shallow groundwater and porewater of the river floodplain may affect the distribution and health of the floodplain vegetation.

Reconstruction of the Eocene Arctic Ocean Using Ichthyolith Isotope Analyses

NASA Astrophysics Data System (ADS)

Gleason, J. D.; Thomas, D. J.; Moore, T. C.; Waddell, L. M.; Blum, J. D.; Haley, B. A.

2007-12-01

Nd, Sr, O and C isotopic compositions of Eocene fish debris (teeth, bones, scales), and their reduced organic coatings, have been used to reconstruct water mass composition, water column structure, surface productivity and salinities of the Arctic Ocean Basin at Lomonosov Ridge between 55 and 44 Ma. Cleaned ichthyolith samples from IODP Expedition 302 (ACEX) record epsilon Nd values that range from -5.7 to -7.8, distinct from modern Arctic Intermediate Water (-10.5) and North Atlantic Deep Water. These Nd values may record some exchange with Pacific/Tethyan water masses, but inputs from local continental sources are more likely. Sr isotopic values are consistent with a brackish-to-fresh water surface layer (87Sr/86Sr = 0.7079-0.7087) that was poorly mixed with Eocene global seawater (0.7077-0.7078). Leaching experiments show reduced organic coatings to be more radiogenic (>0.7090) than cleaned ichthyolith phosphate. Ichthyolith Sr isotopic variations likely reflect changes in localized river input as a function of shifts in the Arctic hydrologic cycle, and 87Sr/86Sr values might be used as a proxy for surface water salinity. Model mixing calculations indicate salinities of 5 to 20 per mil, lower than estimates based on O isotopes from fish bone carbonate (16 to 26 per mil). Significant salinity drops (i.e., 55 Ma PETM and 48.5 Ma Azolla event) registered in oxygen isotopes do not show large excursions in the 87Sr/86Sr data. Carbon isotopes in fish debris record a spike in organic activity at 48.5 Ma (Azolla event), and otherwise high-productivity waters between 55 and 44 Ma. The combined Sr-Nd-O-C isotopic record is consistent with highly restricted basin-wide circulation in the Eocene, indicative of a highly stratified water column with anoxic bottom waters, a "fresh" water upper layer, and enhanced continental runoff during warm intervals until the first appearance of ice rafted debris at 45 Ma.

An integrated model for assessing both crop productivity and agricultural water resources at a large scale

NASA Astrophysics Data System (ADS)

Okada, M.; Sakurai, G.; Iizumi, T.; Yokozawa, M.

2012-12-01

Agricultural production utilizes regional resources (e.g. river water and ground water) as well as local resources (e.g. temperature, rainfall, solar energy). Future climate changes and increasing demand due to population increases and economic developments would intensively affect the availability of water resources for agricultural production. While many studies assessed the impacts of climate change on agriculture, there are few studies that dynamically account for changes in water resources and crop production. This study proposes an integrated model for assessing both crop productivity and agricultural water resources at a large scale. Also, the irrigation management to subseasonal variability in weather and crop response varies for each region and each crop. To deal with such variations, we used the Markov Chain Monte Carlo technique to quantify regional-specific parameters associated with crop growth and irrigation water estimations. We coupled a large-scale crop model (Sakurai et al. 2012), with a global water resources model, H08 (Hanasaki et al. 2008). The integrated model was consisting of five sub-models for the following processes: land surface, crop growth, river routing, reservoir operation, and anthropogenic water withdrawal. The land surface sub-model was based on a watershed hydrology model, SWAT (Neitsch et al. 2009). Surface and subsurface runoffs simulated by the land surface sub-model were input to the river routing sub-model of the H08 model. A part of regional water resources available for agriculture, simulated by the H08 model, was input as irrigation water to the land surface sub-model. The timing and amount of irrigation water was simulated at a daily step. The integrated model reproduced the observed streamflow in an individual watershed. Additionally, the model accurately reproduced the trends and interannual variations of crop yields. To demonstrate the usefulness of the integrated model, we compared two types of impact assessment of climate change on crop productivity in a watershed. The first was carried out by the large-scale crop model alone. The second was carried out by the integrated model of the large-scale crop model and the H08 model. The former projected that changes in temperature and precipitation due to future climate change would give rise to increasing the water stress in crops. Nevertheless, the latter projected that the increasing amount of agricultural water resources in the watershed would supply sufficient amount of water for irrigation, consequently reduce the water stress. The integrated model demonstrated the importance of taking into account the water circulation in watershed when predicting the regional crop production.

Culvert Analysis Program Graphical User Interface 1.0--A preprocessing and postprocessing tool for estimating flow through culvert

USGS Publications Warehouse

Bradley, D. Nathan

2013-01-01

The peak discharge of a flood can be estimated from the elevation of high-water marks near the inlet and outlet of a culvert after the flood has occurred. This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks on trees or buildings. When combined with the cross-sectional geometry of the channel upstream from the culvert and the culvert size, shape, roughness, and orientation, the high-water marks define a water-surface profile that can be used to estimate the peak discharge by using the methods described by Bodhaine (1968). This type of measurement is in contrast to a “direct” measurement of discharge made during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a streamgage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the streamgage, resulting in more accurate computation of high flows. The Culvert Analysis Program (CAP) (Fulford, 1998) is a command-line program written in Fortran for computing peak discharges and culvert rating surfaces or curves. CAP reads input data from a formatted text file and prints results to another formatted text file. Preparing and correctly formatting the input file may be time-consuming and prone to errors. This document describes the CAP graphical user interface (GUI)—a modern, cross-platform, menu-driven application that prepares the CAP input file, executes the program, and helps the user interpret the output

Thermal infrared remote sensing of water temperature in riverine landscapes

USGS Publications Warehouse

Handcock, Rebecca N.; Torgersen, Christian E.; Cherkauer, Keith A.; Gillespie, Alan R.; Klement, Tockner; Faux, Russell N.; Tan, Jing; Carbonneau, Patrice E.; Piégay, Hervé

2012-01-01

Water temperature in riverine landscapes is an important regional indicator of water quality that is influenced by both ground- and surface-water inputs, and indirectly by land use in the surrounding watershed (Brown and Krygier, 1970; Beschta et al., 1987; Chen et al., 1998; Poole and Berman, 2001).Coldwater fishes such as salmon and trout are sensitive to elevated water temperature; therefore, water temperature must meet management guidelines and quality standards, which aim to create a healthy environment for endangered populations (McCullough et al., 2009). For example, in the USA, the Environmental Protection Agency (EPA) has established water quality standards to identify specific temperature criteria to protect coldwater fishes (Environmental Protection Agency, 2003). Trout and salmon can survive in cool-water refugia even when temperatures at other measurement locations are at or above the recommended maximums (Ebersole et al., 2001; Baird and Krueger, 2003; High et al., 2006). Spatially extensive measurements of water temperature are necessary to locate these refugia, to identify the location of ground- and surface-water inputs to the river channel, and to identify thermal pollution sources. Regional assessment of water temperature in streams and rivers has been limited by sparse sampling in both space and time. Water temperature has typically been measured using a network of widely distributed instream gages, which record the temporal change of the bulk, or kinetic, temperature of the water (Tk) at specific locations. For example, the State of Washington (USA) recorded water quality conditions at 76 stations within the Puget Lowlands eco region, which contains 12,721 km of streams and rivers (Washington Department of Ecology, 1998). Such gages are sparsely distributed, are typically located only in larger streams and rivers, and give limited information about the spatial distribution of water temperature.

Thermal infrared remote sensing of water temperature in riverine landscapes: Chapter 5

USGS Publications Warehouse

Carbonneau, Rebecca N.; Piégay, Hervé; Handcock, R.N; Torgersen, Christian E.; Cherkauer, K.A; Gillespie, A.R; Tockner, K; Faux, R. N.; Tan, Jing

2012-01-01

Water temperature in riverine landscapes is an important regional indicator of water quality that is influenced by both ground- and surface-water inputs, and indirectly by land use in the surrounding watershed (Brown and Krygier, 1970; Beschta et al., 1987; Chen et al., 1998; Poole and Berman, 2001). Coldwater fishes such as salmon and trout are sensitive to elevated water temperature; therefore, water temperature must meet management guidelines and quality standards, which aim to create a healthy environment for endangered populations (McCullough et al., 2009). For example, in the USA, the Environmental Protection Agency (EPA) has established water quality standards to identify specific temperature criteria to protect coldwater fishes (Environmental Protection Agency, 2003). Trout and salmon can survive in cool-water refugia even when temperatures at other measurement locations are at or above the recommended maximums (Ebersole et al., 2001; Baird and Krueger, 2003; High et al., 2006). Spatially extensive measurements of water temperature are necessary to locate these refugia, to identify the location of ground- and surface-water inputs to the river channel, and to identify thermal pollution sources. Regional assessment of water temperature in streams and rivers has been limited by sparse sampling in both space and time. Water temperature has typically been measured using a network of widely distributed instream gages, which record the temporal change of the bulk, or kinetic, temperature of the water (Tk) at specific locations. For example, the State of Washington (USA) recorded water quality conditions at 76 stations within the Puget Lowlands eco region, which contains 12,721 km of streams and rivers (Washington Department of Ecology, 1998). Such gages are sparsely distributed, are typically located only in larger streams and rivers, and give limited information about the spatial distribution of water temperature (Cherkauer et al., 2005).

Real-Time monitoring of the eutrophication and hypoxia off the Changjiang Estuary

NASA Astrophysics Data System (ADS)

Chen, J. F.

2016-02-01

Inputs of anthropogenic nutrients and carbon dioxide-rich waters to the coastal waters can not only lead to eutrophication in the surface water and hypoxia in the bottom water, but also will enhance acidification of coastal water. In order to understand the details mechanism of concurrence of eutrophication and hypoxia in the Changjiang Estuary, a real time monitoring system has been established since 2010 under the support of Chinese National Key Technologies R&D Program and Chinese Marine Research Special Funds for Public Welfare Projects. The platforms of the monitoring system includes a 3-meter buoy with water column chain unit and a seabed mounted unit, the sensors includes those can detect wind speed and direction, air and water temperature, salinity, currents, PAR, DO, pH, nutrients, Chl a, turbidity and pCO2 etc.. Two highlights of our scientific findings will introduced in this presentation, one is how typhoon affected the coastal hypoxia (positive and negative), and the other is how fresh water input induced a algal bloom in the Changjiang Estuary in summer.

Recovery of atmospheric refractivity profiles from simulated satellite-to-satellite tracking data

NASA Technical Reports Server (NTRS)

Murray, C. W., Jr.; Rangaswamy, S.

1975-01-01

Techniques for recovering atmospheric refractivity profiles from simulated satellite-to-satellite tracking data are documented. Examples are given using the geometric configuration of the ATS-6/NIMBUS-6 Tracking Experiment. The underlying refractivity model for the lower atmosphere has the spherically symmetric form N = exp P(s) where P(s) is a polynomial in the normalized height s. For the simulation used, the Herglotz-Wiechert technique recovered values which were 0.4% and 40% different from the input values at the surface and at a height of 33 kilometers, respectively. Using the same input data, the model fitting technique recovered refractivity values 0.05% and 1% different from the input values at the surface and at a height of 50 kilometers, respectively. It is also shown that if ionospheric and water vapor effects can be properly modelled or effectively removed from the data, pressure and temperature distributions can be obtained.

Uncertainty analysis of the Operational Simplified Surface Energy Balance (SSEBop) model at multiple flux tower sites

USGS Publications Warehouse

Chen, Mingshi; Senay, Gabriel B.; Singh, Ramesh K.; Verdin, James P.

2016-01-01

Evapotranspiration (ET) is an important component of the water cycle – ET from the land surface returns approximately 60% of the global precipitation back to the atmosphere. ET also plays an important role in energy transport among the biosphere, atmosphere, and hydrosphere. Current regional to global and daily to annual ET estimation relies mainly on surface energy balance (SEB) ET models or statistical and empirical methods driven by remote sensing data and various climatological databases. These models have uncertainties due to inevitable input errors, poorly defined parameters, and inadequate model structures. The eddy covariance measurements on water, energy, and carbon fluxes at the AmeriFlux tower sites provide an opportunity to assess the ET modeling uncertainties. In this study, we focused on uncertainty analysis of the Operational Simplified Surface Energy Balance (SSEBop) model for ET estimation at multiple AmeriFlux tower sites with diverse land cover characteristics and climatic conditions. The 8-day composite 1-km MODerate resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) was used as input land surface temperature for the SSEBop algorithms. The other input data were taken from the AmeriFlux database. Results of statistical analysis indicated that the SSEBop model performed well in estimating ET with an R2 of 0.86 between estimated ET and eddy covariance measurements at 42 AmeriFlux tower sites during 2001–2007. It was encouraging to see that the best performance was observed for croplands, where R2 was 0.92 with a root mean square error of 13 mm/month. The uncertainties or random errors from input variables and parameters of the SSEBop model led to monthly ET estimates with relative errors less than 20% across multiple flux tower sites distributed across different biomes. This uncertainty of the SSEBop model lies within the error range of other SEB models, suggesting systematic error or bias of the SSEBop model is within the normal range. This finding implies that the simplified parameterization of the SSEBop model did not significantly affect the accuracy of the ET estimate while increasing the ease of model setup for operational applications. The sensitivity analysis indicated that the SSEBop model is most sensitive to input variables, land surface temperature (LST) and reference ET (ETo); and parameters, differential temperature (dT), and maximum ET scalar (Kmax), particularly during the non-growing season and in dry areas. In summary, the uncertainty assessment verifies that the SSEBop model is a reliable and robust method for large-area ET estimation. The SSEBop model estimates can be further improved by reducing errors in two input variables (ETo and LST) and two key parameters (Kmax and dT).

Spatial distribution of perchlorate, iodide and thiocyanate in the aquatic environment of Tianjin, China: environmental source analysis.

PubMed

Qin, Xiaolei; Zhang, Tao; Gan, Zhiwei; Sun, Hongwen

2014-09-01

Although China is the largest producer of fireworks (perchlorate-containing products) in the world, the pathways through which perchlorate enters the environment have not been characterized completely in this country. In this study, perchlorate, iodide and thiocyanate were measured in 101 water samples, including waste water, surface water, sea water and paired samples of rain water and surface runoff collected in Tianjin, China. The concentrations of the target anions were generally on the order of rain>surface water≈waste water treatment plant (WWTP) influent>WWTP effluent. High concentrations of perchlorate, iodide and thiocyanate were detected in rain samples, ranging from 0.35 to 27.3 (median: 4.05), 0.51 to 8.33 (2.92), and 1.31 to 107 (5.62) ngmL(-)(1), respectively. Furthermore, the concentrations of the target anions in rain samples were significantly (r=0.596-0.750, p<0.01) positively correlated with the concentrations obtained in the paired surface runoff samples. The anions tested showed a clear spatial distribution, and higher concentrations were observed in the upper reaches of rivers, sea waters near the coast, and rain-surface runoff pairs sampled in urban areas. Our results revealed that precipitation may act as an important source of perchlorate, iodide and thiocyanate in surface water. Moreover, iodide concentrations in the Haihe River and Dagu Drainage Canal showed a good correlation with an ideal marker (acesulfame) of domestic waste water, indicating that input from domestic waste water was an important source of iodide in the surface waters of Tianjin. Copyright © 2014 Elsevier Ltd. All rights reserved.

LAND-COVER CHANGE AND ITS IMPACT ON NUTRIENT EXPORT VARIANCE

EPA Science Inventory

Conversion of natural or semi-natural vegetation to anthropogenic use is widely cited as one of the principal threats to ecosystems worldwide. One consequence of these landcover conversions is increased input of nutrients into surface waters, which promotes eutrophication, noxiou...

South Platte River Basin Data Browser Report

EPA Science Inventory

The purpose of this data browser is to provide a spatial toolkit that delivers primary data that can be used for primary input information for assessments related to environmental endpoints, e.g. surface water hydrology and habitat mapping, related to ecosystem services. A neces...

Water-carbon Links in a Tropical Forest: How Interbasin Groundwater Flow Affects Carbon Fluxes and Ecosystem Carbon Budgets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genereux, David; Osburn, Christopher; Oberbauer, Steven

This report covers the outcomes from a quantitative, interdisciplinary field investigation of how carbon fluxes and budgets in a lowland tropical rainforest are affected by the discharge of old regional groundwater into streams, springs, and wetlands in the forest. The work was carried out in a lowland rainforest of Costa Rica, at La Selva Biological Station. The research shows that discharge of regional groundwater high in dissolved carbon dioxide represents a significant input of carbon to the rainforest "from below", an input that is on average larger than the carbon input "from above" from the atmosphere. A stream receiving dischargemore » of regional groundwater had greatly elevated emissions of carbon dioxide (but not methane) to the overlying air, and elevated downstream export of carbon from its watershed with stream flow. The emission of deep geological carbon dioxide from stream water elevates the carbon dioxide concentrations in air above the streams. Carbon-14 tracing revealed the presence of geological carbon in the leaves and stems of some riparian plants near streams that receive inputs of regional groundwater. Also, discharge of regional groundwater is responsible for input of dissolved organic matter with distinctive chemistry to rainforest streams and wetlands. The discharge of regional groundwater in lowland surface waters has a major impact on the carbon cycle in this and likely other tropical and non-tropical forests.« less

Estimating Water Storage Capacity of Existing and Potentially Restorable Wetland Depressions in a Subbasin of the Red River of the North

USGS Publications Warehouse

Gleason, Robert A.; Tangen, Brian A.; Laubhan, Murray K.; Kermes, Kevin E.; Euliss, Ned H.

2007-01-01

Executive Summary Concern over flooding along rivers in the Prairie Pothole Region has stimulated interest in developing spatially distributed hydrologic models to simulate the effects of wetland water storage on peak river flows. Such models require spatial data on the storage volume and interception area of existing and restorable wetlands in the watershed of interest. In most cases, information on these model inputs is lacking because resolution of existing topographic maps is inadequate to estimate volume and areas of existing and restorable wetlands. Consequently, most studies have relied on wetland area to volume or interception area relationships to estimate wetland basin storage characteristics by using available surface area data obtained as a product from remotely sensed data (e.g., National Wetlands Inventory). Though application of areal input data to estimate volume and interception areas is widely used, a drawback is that there is little information available to provide guidance regarding the application, limitations, and biases associated with such approaches. Another limitation of previous modeling efforts is that water stored by wetlands within a watershed is treated as a simple lump storage component that is filled prior to routing overflow to a pour point or gaging station. This approach does not account for dynamic wetland processes that influence water stored in prairie wetlands. Further, most models have not considered the influence of human-induced hydrologic changes, such as land use, that greatly influence quantity of surface water inputs and, ultimately, the rate that a wetland basin fills and spills. The goals of this study were to (1) develop and improve methodologies for estimating and spatially depicting wetland storage volumes and interceptions areas and (2) develop models and approaches for estimating/simulating the water storage capacity of potentially restorable and existing wetlands under various restoration, land use, and climatic scenarios. To address these goals, we developed models and approaches to spatially represent storage volumes and interception areas of existing and potentially restorable wetlands in the upper Mustinka subbasin within Grant County, Minn. We then developed and applied a model to simulate wetland water storage increases that would result from restoring 25 and 50 percent of the farmed and drained wetlands in the upper Mustinka subbasin. The model simulations were performed during the growing season (May-October) for relatively wet (1993; 0.79 m of precipitation) and dry (1987; 0.40 m of precipitation) years. Results from the simulations indicated that the 25 percent restoration scenario would increase water storage by 21-24 percent and that a 50 percent scenario would increase storage by 34-38 percent. Additionally, we estimated that wetlands in the subbasin have potential to store 11.57-20.98 percent of the total precipitation that fell over the entire subbasin area (52,758 ha). Our simulation results indicated that there is considerable potential to enhance water storage in the subbasin; however, evaluation and calibration of the model is necessary before simulation results can be applied to management and planning decisions. In this report we present guidance for the development and application of models (e.g., surface area-volume predictive models, hydrology simulation model) to simulate wetland water storage to provide a basis from which to understand and predict the effects of natural or human-induced hydrologic alterations. In developing these approaches, we tried to use simple and widely available input data to simulate wetland hydrology and predict wetland water storage for a specific precipitation event or a series of events. Further, the hydrology simulation model accounted for land use and soil type, which influence surface water inputs to wetlands. Although information presented in this report is specific to the Mustinka subbasin, the approaches

Hydrogeology and Simulated Ground-Water Flow in the Salt Pond Region of Southern Rhode Island

USGS Publications Warehouse

Masterson, John P.; Sorenson, Jason R.; Stone, Janet R.; Moran, S. Bradley; Hougham, Andrea

2007-01-01

The Salt Pond region of southern Rhode Island extends from Westerly to Narragansett Bay and forms the natural boundary between the Atlantic Ocean and the shallow, highly permeable freshwater aquifer of the South Coastal Basin. Large inputs of fresh ground water coupled with the low flushing rates to the open ocean make the salt ponds particularly susceptible to eutrophication and bacterial contamination. Ground-water discharge to the salt ponds is an important though poorly quantified source of contaminants, such as dissolved nutrients. A ground-water-flow model was developed and used to delineate the watersheds to the salt ponds, including the areas that contribute ground water directly to the ponds and the areas that contribute ground water to streams that flow into ponds. The model also was used to calculate ground-water fluxes to these coastal areas for long-term average conditions. As part of the modeling analysis, adjustments were made to model input parameters to assess potential uncertainties in model-calculated watershed delineations and in ground-water discharge to the salt ponds. The results of the simulations indicate that flow to the salt ponds is affected primarily by the ease with which water is transmitted through a glacial moraine deposit near the regional ground-water divide, and by the specified recharge rate used in the model simulations. The distribution of the total freshwater flow between direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds is affected primarily by simulated stream characteristics, including the streambed-aquifer connection and the stream stage. The simulated position of the ground-water divide and, therefore, the model-calculated watershed delineations for the salt ponds, were affected only by changes in the transmissivity of the glacial moraine. Selected changes in other simulated hydraulic parameters had substantial effects on total freshwater discharge and the distribution of direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds, but still provided a reasonable match to the hydrologic data available for model calibration. To reduce the uncertainty in predictions of watershed areas and ground-water discharge to the salt ponds, additional hydrogeologic data would be required to constrain the model input parameters that have the greatest effect on the simulation results.

Greenhouse gas (CO2 and CH4) emissions from a high altitude hydroelectric reservoir in the tropics (Riogrande II, Colombia)

NASA Astrophysics Data System (ADS)

Guérin, Frédéric; Leon, Juan

2015-04-01

Tropical hydroelectric reservoirs are considered as very significant source of methane (CH4) and carbon dioxide (CO2), especially when flooding dense forest. We report emissions from the Rio Grande II Reservoir located at 2000 m.a.s.l. in the Colombian Andes. The dam was built at the confluence of the Rio Grande and Rio Chico in 1990. The reservoir has a surface of 12 km2, a maximum depth of 40m and a residence time of 2.5 month. Water quality (temperature, oxygen, pH, conductivity), nitrate, ammonium, dissolved and particulate organic carbon (DOC and POC), CO2 and CH4 were monitored bi-monthly during 1.5 year at 9 stations in the reservoir. Diffusive fluxes of CO2 and CH4 and CH4 ebullition were measured at 5 stations. The Rio grande II Reservoir is weakly stratified thermally with surface temperature ranging from 20 to 24°C and a constant bottom temperature of 18°C. The reservoir water column is well oxygenated at the surface and usually anoxic below 10m depth. At the stations close to the tributaries water inputs, the water column is well mixed and oxygenated from the surface to the bottom. As reported for other reservoirs located in "clear water" watersheds, the concentrations of nutrients are low (NO3-<0.1ppm, NH4+<0.2ppm), the concentrations of DOC are high (2-8 mg L-1) and POC concentrations are low (< 3 mg L-1). Surface CH4 concentrations at the central stations of the reservoirs are 0.5 μmol L-1 (0.07-2.14 μmol L-1) and 3 times higher at the stations close to the tributaries inputs (up to 7 μmol L-1). In the hypolimnion, CH4 concentration is <100 μmol L-1 in the wet season and can reach up to 400 μmol L-1 in the dry season. The spatial and temporal variability are lower for CO2. Surface CO2 concentration was on average 72 μmol L-1 (up to 300) and hypolimnic concentration ranged between 250 and 1000 μmol L-1. The CO2 diffusive flux is 517±331 mmol m-2 d-1 with little seasonal and spatial variations. At the center of the reservoir, the median diffusive flux of CH4 is 1.75 mmol m-2 d-1 and sporadic high fluxes (>10 mmol m-2 d-1) were observed during the dry season. Close to the tributaries water inputs where the water column is well mixed, the average diffusive flux is 8 mmol m-2 d-1. CH4 ebullition was 3.5 mmol m-2 d-1 and no ebullition was observed for a water depth higher than 5m. The zone under the influence of the water inputs from tributaries represents 25% of the surface of the reservoir but contributed half of total CH4 emissions from the reservoir (29MgC month-1). Ebullition contributed only to 12% of total CH4 emissions over a year but it contributed up to 60% during the dry season. CH4 emissions from the Rio Grande Reservoir contributed 30% of the total GHG emissions (38GgCO2eq y-1). Overall, this study show that the majority of CH4 emissions from this reservoir occur through hotspot and hot moments and that mountainous reservoir located in the tropics could have emission factors as high as Amazonian reservoirs.

Why Do Organisms in the Atlantic Ocean Produce So Much CaCO3?

NASA Astrophysics Data System (ADS)

Toggweiler, J. R.

2010-12-01

Sediments in the Atlantic are richer in CaCO3 than sediments in the other oceans. Sediment trap observations show that sinking particles in the Atlantic also tend to have more CaCO3 in relation to organic carbon than sinking particles elsewhere. The reason for the extra production of CaCO3 has never been very clear. The Atlantic is unusual because it receives much more than its share of the global input of river water. River water adds alkalinity to the surface ocean while the production of CaCO3 takes it away. In this presentation a new tracer, called Alk*, is derived from the surface alkalinity distribution to highlight the impact of river inputs and the production of CaCO3. If the production of CaCO3 were evenly distributed across the ocean one would expect the Atlantic to have a higher level of Alk* becaused of its river inputs. We find instead that Alk* is lower in the middle of the Atlantic than almost any place else. This, of course, is consistent with the fact that organisms in the Atlantic produce a lot of CaCO3. Comparison with other areas with especially low values of Alk* (Red Sea and northern Arabian Sea) shows that the production of CaCO3 is highly correlated across the ocean with the surface salinity. Hence, we argue that organisms in the Atlantic produce a lot of CaCO3 simply because the Atlantic is so salty. Salty waters, by definition, have more CO3= ions, which increase the supersaturation with respect to calcite and aragonite. This finding, while extremely simple, has major implifications for the impact of ocean acidification on calcifying organisms.

Whole-stream response to nitrate loading in three streams draining agricultural landscapes

USGS Publications Warehouse

Duff, J.H.; Tesoriero, A.J.; Richardson, W.B.; Strauss, E.A.; Munn, M.D.

2008-01-01

Physical, chemical, hydrologic, and biologic factors affecting nitrate (NO3 −) removal were evaluated in three agricultural streams draining orchard/dairy and row crop settings. Using 3-d “snapshots” during biotically active periods, we estimated reach-level NO3 − sources, NO3 − mass balance, in-stream processing (nitrification, denitrification, and NO3 − uptake), and NO3 − retention potential associated with surface water transport and ground water discharge. Ground water contributed 5 to 11% to stream discharge along the study reaches and 8 to 42% of gross NO3 − input. Streambed processes potentially reduced 45 to 75% of ground water NO3 − before discharge to surface water. In all streams, transient storage was of little importance for surface water NO3 − retention. Estimated nitrification (1.6–4.4 mg N m−2 h−1) and unamended denitrification rates (2.0–16.3 mg N m−2 h−1) in sediment slurries were high relative to pristine streams. Denitrification of NO3 − was largely independent of nitrification because both stream and ground water were sources of NO3 − Unamended denitrification rates extrapolated to the reach-scale accounted for <5% of NO3 − exported from the reaches minimally reducing downstream loads. Nitrate retention as a percentage of gross NO3 − inputs was >30% in an organic-poor, autotrophic stream with the lowest denitrification potentials and highest benthic chlorophyll a, photosynthesis/respiration ratio, pH, dissolved oxygen, and diurnal NO3 − variation. Biotic processing potentially removed 75% of ground water NO3 − at this site, suggesting an important role for photosynthetic assimilation of ground water NO3 − relative to subsurface denitrification as water passed directly through benthic diatom beds.

Hydrochemical controls on reservoir nutrient and phytoplankton dynamics under storms.

PubMed

Chen, Nengwang; Mo, Qiongli; Kuo, Yi-Ming; Su, Yuping; Zhong, Yanping

2018-04-01

Eutrophication and undesired algal blooms in surface water are common and have been linked to increasing nutrient loading. Effects of extreme events such as storms on reservoir nutrient and phytoplankton remain unclear. Here we carried out continuous high-frequency measurements in a long and narrow dam reservoir in southeast China during a storm period in June-July 2015. Our results show a strong nutrient-phytoplankton relationship as well as a very rapid response to storm runoff. We observed an increase in total suspended matter (TSM), ammonium (NH 4 -N), and dissolved reactive phosphate (DRP), with a sharp decline in chlorophyll-a (Chl-a) in the high flow periods. Afterward, Chl-a, total phytoplankton abundance and Cyanophyta fraction elevated gradually. Nitrate was diluted at first with increasing discharge before concentration increased, likely following a delayed input of groundwater. Physiochemical parameters and Chl-a were evenly distributed in the water column during the flooding period. However, 10% of NH 4 -N and 25% of DRP were removed in surface water (0-1m) when an algal bloom (Chl-a>30μgL -1 ) occurred 10days after peak discharge. Conversely, total particulate P (TPP) of surface water was 58% higher than in the deeper water. Dynamic factor analysis (DFA) revealed that TSM, NH 4 -N, DRP, total P and discharge significantly explain Chl-a variations following storms (C eff =0.89). These findings highlight that the reservoir ecosystem was vulnerable to pulse input from storm runoff and the Cyanophyta bloom was likely fueled by phosphate and ammonium rather than nitrate. Copyright © 2017 Elsevier B.V. All rights reserved.

Design and optimization of input shapers for liquid slosh suppression

NASA Astrophysics Data System (ADS)

Aboel-Hassan, Ameen; Arafa, Mustafa; Nassef, Ashraf

2009-02-01

The need for fast maneuvering and accurate positioning of flexible structures poses a control challenge. The inherent flexibility in these lightly damped systems creates large undesirable residual vibrations in response to rapid excitations. Several control approaches have been proposed to tackle this class of problems, of which the input shaping technique is appealing in many aspects. While input shaping has been widely investigated to attenuate residual vibrations in flexible structures, less attention was granted to expand its viability in further applications. The aim of this work is to develop a methodology for applying input shaping techniques to suppress sloshing effects in open moving containers to facilitate safe and fast point-to-point movements. The liquid behavior is modeled using finite element analysis. The input shaper parameters are optimized to find the commands that would result in minimum residual vibration. Other objectives, such as improved robustness, and motion constraints such as deflection limiting are also addressed in the optimization scheme. Numerical results are verified on an experimental setup consisting of a small motor-driven water tank undergoing rectilinear motion, while measuring both the tank motion and free surface displacement of the water. The results obtained suggest that input shaping is an effective method for liquid slosh suppression.

Library Construction from Subnanogram DNA for Pelagic Sea Water and Deep-Sea Sediments

PubMed Central

Hirai, Miho; Nishi, Shinro; Tsuda, Miwako; Sunamura, Michinari; Takaki, Yoshihiro; Nunoura, Takuro

2017-01-01

Shotgun metagenomics is a low biased technology for assessing environmental microbial diversity and function. However, the requirement for a sufficient amount of DNA and the contamination of inhibitors in environmental DNA leads to difficulties in constructing a shotgun metagenomic library. We herein examined metagenomic library construction from subnanogram amounts of input environmental DNA from subarctic surface water and deep-sea sediments using two library construction kits: the KAPA Hyper Prep Kit and Nextera XT DNA Library Preparation Kit, with several modifications. The influence of chemical contaminants associated with these environmental DNA samples on library construction was also investigated. Overall, shotgun metagenomic libraries were constructed from 1 pg to 1 ng of input DNA using both kits without harsh library microbial contamination. However, the libraries constructed from 1 pg of input DNA exhibited larger biases in GC contents, k-mers, or small subunit (SSU) rRNA gene compositions than those constructed from 10 pg to 1 ng DNA. The lower limit of input DNA for low biased library construction in this study was 10 pg. Moreover, we revealed that technology-dependent biases (physical fragmentation and linker ligation vs. tagmentation) were larger than those due to the amount of input DNA. PMID:29187708

Using WorldView-2 Imagery to Track Flooding in Thailand in a Multi-Asset Sensorweb

NASA Technical Reports Server (NTRS)

McLaren, David; Doubleday, Joshua; Chien, Steve

2012-01-01

For the flooding seasons of 2011-2012 multiple space assets were used in a "sensorweb" to track major flooding in Thailand. Worldview-2 multispectral data was used in this effort and provided extremely high spatial resolution (2m / pixel) multispectral (8 bands at 0.45-1.05 micrometer spectra) data from which mostly automated workflows derived surface water extent and volumetric water information for use by a range of NGO and national authorities. We first describe how Worldview-2 and its data was integrated into the overall flood tracking sensorweb. We next describe the use of Support Vector Machine learning techniques that were used to derive surface water extent classifiers. Then we describe the fusion of surface water extent and digital elevation map (DEM) data to derive volumetric water calculations. Finally we discuss key future work such as speeding up the workflows and automating the data registration process (the only portion of the workflow requiring human input).

Review of literature on the finite-element solution of the equations of two-dimensional surface-water flow in the horizontal plane

USGS Publications Warehouse

Lee, Jonathan K.; Froehlich, David C.

1987-01-01

Published literature on the application of the finite-element method to solving the equations of two-dimensional surface-water flow in the horizontal plane is reviewed in this report. The finite-element method is ideally suited to modeling two-dimensional flow over complex topography with spatially variable resistance. A two-dimensional finite-element surface-water flow model with depth and vertically averaged velocity components as dependent variables allows the user great flexibility in defining geometric features such as the boundaries of a water body, channels, islands, dikes, and embankments. The following topics are reviewed in this report: alternative formulations of the equations of two-dimensional surface-water flow in the horizontal plane; basic concepts of the finite-element method; discretization of the flow domain and representation of the dependent flow variables; treatment of boundary conditions; discretization of the time domain; methods for modeling bottom, surface, and lateral stresses; approaches to solving systems of nonlinear equations; techniques for solving systems of linear equations; finite-element alternatives to Galerkin's method of weighted residuals; techniques of model validation; and preparation of model input data. References are listed in the final chapter.

Emerging contaminants in surface waters in China—a short review

NASA Astrophysics Data System (ADS)

Yang, Guang; Fan, Maohong; Zhang, Guangming

2014-07-01

Emerging contaminants (ECs) have drawn attention to many countries due to their persistent input and potential threat to human health and the environment. This article reviews the current contamination sources and their status for surface waters in China. The contamination levels of ECs in surface waters are in the range ng L-1 to μg L-1 in China, apparently about the same as the situation in other countries. ECs enter surface water via runoff, drainage, rainfall, and wastewater treatment effluent. The frequency of occurrence of ECs increased rapidly from 2006 to 2011; a significant reason is the production and consumption of pharmaceuticals and personal care products. As for the distribution of EC pollution in China, the frequency of occurrence of ECs in eastern regions is higher than in western regions. A majority of EC studies have focused on surface waters of the Haihe River and Pearl River watersheds due to their highly developed industries and intense human activity. Legislative and administrative regulation of ECs is lacking in China. To remove ECs, a number of technologies, such as absorption by activated carbon, membrane filtration technology, and advanced oxidation processes, have been researched.

Water balance model for mean annual hydrogen and oxygen isotope distributions in surface waters of the contiguous United States

NASA Astrophysics Data System (ADS)

Bowen, Gabriel J.; Kennedy, Casey D.; Liu, Zhongfang; Stalker, Jeremy

2011-12-01

The stable H and O isotope composition of river and stream water records information on runoff sources and land-atmosphere water fluxes within the catchment and is a potentially powerful tool for network-based monitoring of ecohydrological systems. Process-based hydrological models, however, have thus far shown limited power to replicate observed large-scale variation in U.S. surface water isotope ratios. Here we develop a geographic information system-based model to predict long-term annual average surface water isotope ratios across the contiguous United States. We use elevation-explicit, gridded precipitation isotope maps as model input and data from a U.S. Geological Survey monitoring program for validation. We find that models incorporating monthly variation in precipitation-evapotranspiration (P-E) amounts account for the majority (>89%) of isotopic variation and have reduced regional bias relative to models that do not consider intra-annual P-E effects on catchment water balance. Residuals from the water balance model exhibit strong spatial patterning and correlations that suggest model residuals isolate additional hydrological signal. We use interpolated model residuals to generate optimized prediction maps for U.S. surface water δ2H and δ18O values. We show that the modeled surface water values represent a relatively accurate and unbiased proxy for drinking water isotope ratios across the United States, making these data products useful in ecological and criminal forensics applications that require estimates of the local environmental water isotope variation across large geographic regions.

Low input verses traditional turfgrass: Comparing runoff quantity and quality

USDA-ARS?s Scientific Manuscript database

Strategies used to maintain managed biological systems, including golf course turf, often involve application of fertilizer and pesticides to optimize plant health and protection. The transport of applied chemicals with runoff to surrounding surface waters has been shown to result in enhanced algal ...

Variability of pesticides and nitrates concentrations along a river transect: chemical and isotopic evidence of groundwater - surface water interconnections

NASA Astrophysics Data System (ADS)

Baran, Nicole; Petelet-Giraud, Emmanuelle; Saplairoles, Maritxu

2015-04-01

Groundwater quality is increasingly monitored in Europe where various levels of nitrate and pesticide and/or metabolite contamination have been demonstrated (Loos et al., 2010, Stuart et al., 2012). The Groundwater Daughter Directive (2006/118/EC) to Water Framework Directive (WFD) particularly requires measures to prevent or limit inputs of pollutants into groundwater and compliance with good chemical status criteria (based on EU standards of nitrate and pesticides). The WFD mentioned the need to protect groundwater but also to have a particular regard to its impact and interrelationship with associated surface waters and directly dependent terrestrial Ecosystems. The Ariège river basin (SW France - 538 km²) is an alluvial plain under high agricultural pressure leading to a contamination of the aquifer by several pesticides and metabolites (Amalric et al., 2013). The Crieu is an allochtone river, crossing the plain (~ 10 km length) before joining the Ariège River. The Crieu is often dry in its middle section suggesting water leakage from surface water towards groundwater. At the opposite, the permanent flow observed downstream suggests an input of groundwater into surface water. In May 2014, while the Crieu flow was continuous through the plain, 7 river samples were collected and analyzed for pesticides, major ions, strontium concentration and isotopes. In situ measurements of electric conductivity were also performed as well as flow gauging. Two groundwaters close to the river were also sampled. The flow gauging measurements show a decreasing river discharge in the central area of the Crieu River, suggesting surface water leakage towards groundwater. Nevertheless, the electric conductivity increases along the river flow as well as some pesticides and nitrates concentrations. This chemical evolution of the river water is thus inconsistent with a simple water infiltration and another source of dissolved solutes is required to explain the increased of concentration. Finally, downstream the quantified pesticides were different from those observed in the upper part of the Crieu but similar to those observed in groundwater. Sr isotopes together with major elements and Sr concentrations allow to identify 3 distinct end-members to explain the river quality evolution : 1) surface water, 2) groundwater and 3) sub-surface water. On this basis, we first demonstrate that the contribution of the different end-members to the river flow is highly variable from upstream to downstream. Secondly, we evidence water exchanges between the river and the groundwater compartment and vice-versa. The combination of the isotopic and geochemical approaches was essential to understand the complex relations and exchanges between surface and ground-waters occurring in few kilometers along the Crieu River. This understanding allows the comprehension of spatial variability of surface water quality. This is of primary importance when to help water managers to select relevant sampling points to be monitored in the framework of the WFD. Amalric L., et al. (2013). International Journal of Environmental Analytical Chemistry, 93: 1660-1675 Loos R. et al. (2010). Water Research, 44: 4115-4126 Stuart M. et al. (2012). Science of the Total Environment, 416: 1-21.

C-band radar observes water level change in swamp forests

USGS Publications Warehouse

Lu, Zhong; Crane, Mike; Kwoun, Oh-Ig; Wells, Christopher J.; Rykhus, Russ

2005-01-01

Wetlands cover more than 4% of the Earth's land surface and interact with hydrologic, biogeochemical, and sediment transport processes that are fundamental in understanding ecological and climatic changes [Alsdorf et al, 2003; Prigent et al., 2001 ; Melack and Forsberg, 2000;Dunne et al., 1998]. Measurement of water level changes in wetlands, and consequently of changes in water storage capacity, provides a required input for hydrologic models, and is required to comprehensively assess flood hazards [e.g., Coe, 1998].

An Assessment of the Potential Impacts on Zooplankton and Fish of Ocean Dredged Material at the Norfolk Disposal Site.

DTIC Science & Technology

1984-09-07

McConaugha et al., 1983). This retention mechanism is entirely dependent upon southerly winds of sufficient magnitude to drive a northward current. Since the...Chesapeake Bay Inflow Streamline Patterns for Periods of Northerly (Figure 6a) and Southerly (Figure 6b) Winds ..... ...... .... 2-2 7 Surface Salinity ...layer flow: Low salinity water from rivers and other fresh water inputs moves seaward in the upper layer, while high salinity shelf water is drawn into

Mitigation of nutrient losses via surface runoff from rice cropping systems with alternate wetting and drying irrigation and site-specific nutrient management practices.

PubMed

Liang, X Q; Chen, Y X; Nie, Z Y; Ye, Y S; Liu, J; Tian, G M; Wang, G H; Tuong, T P

2013-10-01

Resource-conserving irrigation and fertilizer management practices have been developed for rice systems which may help address water quality concerns by reducing N and P losses via surface runoff. Field experiments under three treatments, i.e., farmers' conventional practice (FCP), alternate wetting and drying (AWD), and AWD integrated with site-specific nutrient management (AWD + SSNM) were carried out during two rice seasons at two sites in the southwest Yangtze River delta region. Across site years, results indicated that under AWD irrigation (i.e., AWD and AWD + SSNM), water inputs were reduced by 13.4~27.5 % and surface runoff was reduced by 30.2~36.7 % compared to FCP. When AWD was implemented alone, total N and P loss masses via surface runoff were reduced by 23.3~30.4 % and 26.9~31.7 %, respectively, compared to FCP. However, nutrient concentrations of surface runoff did not decrease under AWD alone. Under AWD + SSNM, total N and P loss masses via surface runoff were reduced to a greater extent than AWD alone (39.4~47.6 % and 46.1~48.3 % compared to FCP, respectively), while fertilizer inputs and N surpluses significantly decreased and rice grain yields increased relative to FCP. Therefore, by more closely matching nutrient supply with crop demand and reducing both surface runoff and nutrient concentrations of surface runoff, our results demonstrate that integration of AWD and SSNM practices can mitigate N and P losses via surface runoff from rice fields while maintaining high yields.

Slope-Area Computation Program Graphical User Interface 1.0—A Preprocessing and Postprocessing Tool for Estimating Peak Flood Discharge Using the Slope-Area Method

USGS Publications Warehouse

Bradley, D. Nathan

2012-01-01

The slope-area method is a technique for estimating the peak discharge of a flood after the water has receded (Dalrymple and Benson, 1967). This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks (HWMs) on trees or buildings. These indicators of flood stage are combined with measurements of the cross-sectional geometry of the stream, estimates of channel roughness, and a mathematical model that balances the total energy of the flow between cross sections. This is in contrast to a “direct” measurement of discharge during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a gage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the stream gage, resulting in more accurate computation of high flows. The Slope-Area Computation program (SAC; Fulford, 1994) is an implementation of the slope-area method that computes a peak-discharge estimate from inputs of water-surface slope (from surveyed HWMs), channel geometry, and estimated channel roughness. SAC is a command line program written in Fortran that reads input data from a formatted text file and prints results to another formatted text file. Preparing the input file can be time-consuming and prone to errors. This document describes the SAC graphical user interface (GUI), a crossplatform “wrapper” application that prepares the SAC input file, executes the program, and helps the user interpret the output. The SAC GUI is an update and enhancement of the slope-area method (SAM; Hortness, 2004; Berenbrock, 1996), an earlier spreadsheet tool used to aid field personnel in the completion of a slope-area measurement. The SAC GUI reads survey data, develops a plan-view plot, water-surface profile, cross-section plots, and develops the SAC input file. The SAC GUI also develops HEC-2 files that can be imported into HEC–RAS.

Water-level fluctuation in wetlands as a function of landscape condition in the prairie pothole region

USGS Publications Warehouse

Euliss, Ned H.; Mushet, David M.

1996-01-01

We evaluated water-level fluctuation (maximum water depth - minimum water depth/catchment size) in 12 temporary, 12 seasonal, and 12 semipermanent wetlands equally distributed among landscapes dominated by tilled agricultural lands and landscapes dominated by grassland. Water levels fluctuated an average of 14.14 cm in wetlands within tilled agricultural landscapes, while water levels in wetlands within grassland landscapes fluctuated an average of only 4.27 cm. Tillage reduces the natural capacity of catch meets to mitigate surface flow into wetland basins during precipitation events, resulting in greater water-level fluctuations in wetlands with tilled catchments. In addition, water levels in temporary and seasonal wetlands fluctuated an average of 13.74 cm and 11.82 cm, respectively, while water levels in semipermanent wetlands fluctuated only 2.77 cm. Semipermanent wetlands receive a larger proportion of their water as input from ground water than do either temporary or seasonal wetlands. This input of water from the ground has a stabilizing effect on water-levels of semipermanent wetlands. Increases in water-level fluctuation due to tillage or due to alteration of ground-water hydrology may ultimately affect the composition of a wetland's flora and fauna. In this paper, we also describe an inexpensive device for determining absolute maximum and minimum water levels in wetlands.

Hydraulic characteristics of the New River in the New River Gorge National River, West Virginia

USGS Publications Warehouse

Wiley, J.B.; Appel, David H.

1989-01-01

Traveltime, dispersion, water-surface and streambed profiles, and cross-section data were collected for use in application of flow and solute-transport models to the New River in the New River Gorge National River, West Virginia. Dye clouds subjected to increasing and decreasing flow rates (unsteady flow) showed that increasing flows shorten the cloud and decreasing flows lengthen the cloud. After the flow rate was changed and the flow was again steady, traveltime and dispersion characteristics were determined by the new rate of flow. Seven stage/streamflow relations identified the general changes of stream geometry throughout the study reach. Channel cross sections were estimated for model input. Low water and streambed profiles were developed from surveyed water surface elevations and water depths. (USGS)

Distribution and Risk Assessment of Antibiotics in a Typical River in North China Plain.

PubMed

Li, Qingzhao; Gao, Junxia; Zhang, Qiuling; Liang, Lizhen; Tao, He

2017-04-01

We evaluated the occurrence and distribution of 12 antibiotics from the sulfonamide (SAs), fluoroquinolone (FQs) and tetracycline (TCs) groups in the Weihe River, North China. The total antibiotic concentrations in surface water, pore water, and sediment samples ranged from 11.1 to 173.1 ng/L, 5.8 to 103.9 ng/L, and 9.5 to 153.4 μg/kg, respectively. The values of the sediment-water partitioning coefficient in the Weihe River varied widely, from not detected to 943, 2213, and 2405 L/kg for SAs, FQs, and TCs, respectively. The values of the partitioning coefficients between sediment and surface water were generally lower than those between sediment and pore water, which indicated ongoing inputs to the water. The risk assessment showed that there were relatively high ecological risks to aquatic algae in this area from sulfamethoxazole, norfloxacin, tetracycline, ofloxacin, and ciprofloxacin.

The use of organic markers in the differentiation of organic inputs to aquatic systems

NASA Astrophysics Data System (ADS)

Reeves, A. D.

1995-04-01

In previous projects the estuarine distributions of a variety of molecular organic markers have been described and discussed in relation to sources, transport mechanisms and fates of anthropogenic and biogenic inputs to estuaries. Molecular markers have been used successfully to establish terrestrial inputs to marine water and to trace pollutants in water-ways. One of the components selected for study was lignin. Lignin compounds are phenolic polymers that occur as major constituents of the cell walls of vascular plants. Their source, natural abundance, wide distribution and resistance to microbial degradation render them good terrestrial markers and, via their phenolic aldehyde oxidation products, afford characterisation of their source material. In previous work, ratios of various lignin components suggest that permanently suspended material contains a significant proportion of degraded angiosperm tissues whereas, in resuspended material, a component of gymnosperm material is indicated. Comparison of the lignin concentrations in the suspended material with those in underlying sediment reveals that the permanently suspended material is preferentially enriched in lignin. This is due, at least in part, to the relative buoyancy of lignin-containing prticles which causes them to float in near-surface water. This paper considers whether such methodology can be usefully applied to the determination of terrestrial inputs to lentic environments.

Unusually high (210)Po activities in the surface water of the Zhubi Coral Reef Lagoon in the South China Sea.

PubMed

Yang, Weifeng; Huang, Yipu; Chen, Min; Qiu, Yusheng; Li, Hongbin; Zhang, Lei

2011-10-01

Recent researches revealed the exciting application of (210)Po in tracing carbon and nitrogen cycling in the coral reef system. In order to quantify the recycling of particulate organic nitrogen (PON), both (210)Po and (210)Pb were examined at both high and low tides in the Zhubi Coral Reef lagoon, the South China Sea. Unusually, much higher (210)Po activities and (210)Po/(210)Pb ratios, in comparison with those found in the open seawater and the lagoon subsurface water, showed additional input of (210)Po besides production from in situ(210)Pb in the lagoon surface water. Statistical analysis identified that the reef flat seawater was the additional (210)Po source. Based on a mass balance model, the input rates of (210)Po varied from 0.04 Bq m(-3)year(-1) to 8.41 Bq m(-3)year(-1). On average, the additional (210)Po contributed more than 60% of the total (210)Po. The particulate (210)Po significantly correlated with the concentrations of PON, indicating that diffusion of (210)Po from sediment could be used to quantify the recycling of nitrogen. The average input rate of nitrogen was 16 mmol m(-3)year(-1), which can support up to 11% of the primary production rate. These results suggested that the unusual behavior of (210)Po could provide new insight into the nitrogen recycling in the coral reef system. Copyright © 2011 Elsevier B.V. All rights reserved.

Summary of Organic Wastewater Compounds and Other Water-Quality Data in Charles County, Maryland, October 2007 through August 2008

USGS Publications Warehouse

Lorah, Michelle M.; Soeder, Daniel J.; Teunis, Jessica A.

2010-01-01

The U.S. Geological Survey, in cooperation with the government of Charles County, Maryland, and the Port Tobacco River Conservancy, Inc., conducted a water-quality reconnaissance and sampling investigation of the Port Tobacco River and Nanjemoy Creek watersheds in Charles County during October 2007 and June-August 2008. Samples were collected and analyzed for major ions, nutrients, organic wastewater compounds, and other selected constituents from 17 surface-water sites and 11 well sites (5 of which were screened in streambed sediments to obtain porewater samples). Most of the surface-water sites were relatively widely spaced throughout the Port Tobacco River and Nanjemoy Creek watersheds, although the well sites and some associated surface-water sites were concentrated in one residential community along the Port Tobacco River that has domestic septic systems. Sampling for enterococci bacteria was conducted by the Port Tobacco River Conservancy, Inc., at each site to coordinate with the sampling for chemical constituents. The purpose of the coordinated sampling was to determine correlations between historically high, in-stream bacteria counts and human wastewater inputs. Chemical data for the groundwater, porewater, and surface-water samples are presented in this report.

A new approach to estimating evaporation from lakes and reservoirs based on energy balance and remote sensing data

NASA Astrophysics Data System (ADS)

Majidi, Maysam; Sadeghi, Morteza; Shafiei, Mojtaba; Alizadeh, Amin; Farid, Alireza; Azad, Mohammadreza; Vazifedoust, Majid

2016-04-01

Estimating evaporation from water bodies such as lakes and reservoirs is commonly a difficult task, especially due to the lack of reliable and available ground data. Remote sensing (RS) data has shown a great potential for filling the gap. Nonetheless, interpretation of the RS data (e.g. optical reflectance, thermal emission, etc.) for estimating water evaporation has remained as a challenge. In this paper, we present a novel approach for estimating water evaporation based on satellite RS data and some readily measurable ground data. In the proposed approach, named as "Reference and Water surface Energy Balance (RWEB)", we define a reference surface and then solve the energy balance equation simultaneously for the reference surfaces and water surface. This approach was tested over the Doosti dam reservoir (north east of Iran) using whether station and RS data as well as water temperature measured biweekly along the study. Accuracy of the RWEB algorithm was examined by comparison to the standard "Bowen Ratio Energy Balance (BREB)" RS algorithm. The RMSD value of 0.047 mm/year indicated a good agreement between RWEB and BREB algorithms, while RWEB provides an easier-to-use approach regarding its required input variables.

Extraction and development of inset models in support of groundwater age calculations for glacial aquifers

USGS Publications Warehouse

Feinstein, Daniel T.; Kauffman, Leon J.; Haserodt, Megan J.; Clark, Brian R.; Juckem, Paul F.

2018-06-22

The U.S. Geological Survey developed a regional model of Lake Michigan Basin (LMB). This report describes the construction of five MODFLOW inset models extracted from the LMB regional model and their application using the particle-tracking code MODPATH to simulate the groundwater age distribution of discharge to wells pumping from glacial deposits. The five study areas of the inset model correspond to 8-digit hydrologic unit code (HUC8) basins. Two of the basins are tributary to Lake Michigan from the east, two are tributary to the lake from the west, and one is just west of the western boundary of the Lake Michigan topographic basin. The inset models inherited many of the inputs to the parent LMB model, including the hydrostratigraphy and layering scheme, the hydraulic conductivity assigned to bedrock layers, recharge distribution, and water use in the form of pumping rates from glacial and bedrock wells. The construction of the inset models entailed modifying some inputs, most notably the grid spacing (reduced from cells 5,000 feet on a side in the parent LMB model to 500 feet on a side in the inset models). The refined grid spacing allowed for more precise location of pumped wells and more detailed simulation of groundwater/surface-water interactions. The glacial hydraulic conductivity values, the top bedrock surface elevation, and the surface-water network input to the inset models also were modified. The inset models are solved using the MODFLOW–NWT code, which allows for more robust handling of conditions in unconfined aquifers than previous versions of MODFLOW. Comparison of the MODFLOW inset models reveals that they incorporate a range of hydrogeologic conditions relative to the glacial part of the flow system, demonstrated by visualization and analysis of model inputs and outputs and reflected in the range of ages generated by MODPATH for existing and hypothetical glacial wells. Certain inputs and outputs are judged to be candidate predictors that, if treated statistically, may be capable of explaining much of the variance in the simulated age metrics. One example of a predictor that model results indicate strongly affects simulated age is the depth of the well open interval below the simulated water table. The strength of this example variable as an overall predictor of groundwater age and its relation to other predictors can be statistically tested through the metamodeling process. In this way the inset models are designed to serve as a training area for metamodels that estimate groundwater age in glacial wells, which in turn will contribute to ongoing studies, under the direction of the U.S. Geological Survey National Water Quality Assessment, of contaminant susceptibility of shallow groundwater across the glacial aquifer system.

High-Resolution Water Footprints of Production of the United States

NASA Astrophysics Data System (ADS)

Marston, Landon; Ao, Yufei; Konar, Megan; Mekonnen, Mesfin M.; Hoekstra, Arjen Y.

2018-03-01

The United States is the largest producer of goods and services in the world. Rainfall, surface water supplies, and groundwater aquifers represent a fundamental input to economic production. Despite the importance of water resources to economic activity, we do not have consistent information on water use for specific locations and economic sectors. A national, spatially detailed database of water use by sector would provide insight into U.S. utilization and dependence on water resources for economic production. To this end, we calculate the water footprint of over 500 food, energy, mining, services, and manufacturing industries and goods produced in the United States. To do this, we employ a data intensive approach that integrates water footprint and input-output techniques into a novel methodological framework. This approach enables us to present the most detailed and comprehensive water footprint analysis of any country to date. This study broadly contributes to our understanding of water in the U.S. economy, enables supply chain managers to assess direct and indirect water dependencies, and provides opportunities to reduce water use through benchmarking. In fact, we find that 94% of U.S. industries could reduce their total water footprint more by sourcing from more water-efficient suppliers in their supply chain than they could by converting their own operations to be more water-efficient.

Application of TREECS Modeling System to Strontium-90 for Borschi Watershed near Chernobyl, Ukraine.

PubMed

Johnson, Billy E; Dortch, Mark S

2014-05-01

The Training Range Environmental Evaluation and Characterization System (TREECS™) (http://el.erdc.usace.army.mil/treecs/) is being developed by the U.S. Army Engineer Research and Development Center (ERDC) for the U.S. Army to forecast the fate of munitions constituents (MC) (such as high explosives (HE) and metals) found on firing/training ranges, as well as those subsequently transported to surface water and groundwater. The overall purpose of TREECS™ is to provide environmental specialists with tools to assess the potential for MC migration into surface water and groundwater systems and to assess range management strategies to ensure protection of human health and the environment. The multimedia fate/transport models within TREECS™ are mathematical models of reduced form (e.g., reduced dimensionality) that allow rapid application with less input data requirements compared with more complicated models. Although TREECS™ was developed for the fate of MC from military ranges, it has general applicability to many other situations requiring prediction of contaminant (including radionuclide) fate in multi-media environmental systems. TREECS™ was applied to the Borschi watershed near the Chernobyl Nuclear Power Plant, Ukraine. At this site, TREECS™ demonstrated its use as a modeling tool to predict the fate of strontium 90 ((90)Sr). The most sensitive and uncertain input for this application was the soil-water partitioning distribution coefficient (Kd) for (90)Sr. The TREECS™ soil model provided reasonable estimates of the surface water export flux of (90)Sr from the Borschi watershed when using a Kd for (90)Sr of 200 L/kg. The computed export for the year 2000 was 0.18% of the watershed inventory of (90)Sr compared to the estimated export flux of 0.14% based on field data collected during 1999-2001. The model indicated that assumptions regarding the form of the inventory, whether dissolved or in solid phase form, did not appreciably affect export rates. Also, the percentage of non-exchangeable adsorbed (90)Sr, which is uncertain and affects the amount of (90)Sr available for export, was fixed at 20% based on field data measurements. A Monte Carlo uncertainty analysis was conducted treating Kd as an uncertain input variable with a range of 100-300 L/kg. This analysis resulted in a range of 0.13-0.27% of inventory exported to surface water compared to 0.14% based on measured field data. Based on this model application, it was concluded that the export of (90)Sr from the Borschi watershed to surface water is predominantly a result of soil pore water containing dissolved (90)Sr being diverted to surface waters that eventually flow out of the watershed. The percentage of non-exchangeable adsorbed (90)Sr and the soil-water Kd are the two most sensitive and uncertain factors affecting the amount of export. The 200-year projections of the model showed an exponential decline in (90)Sr export fluxes from the watershed that should drop by a factor of 10 by the year 2100. This presentation will focus on TREECS capabilities and the case study done for the Borschi Watershed. Published by Elsevier Ltd.

Questa baseline and pre-mining ground-water quality investigation. 5. Well installation, water-level data, and surface- and ground-water geochemistry in the Straight Creek drainage basin, Red River Valley, New Mexico, 2001-03

USGS Publications Warehouse

Naus, Cheryl A.; McCleskey, R. Blaine; Nordstrom, D. Kirk; Donohoe, Lisa C.; Hunt, Andrew G.; Paillet, Frederick L.; Morin, Roger H.; Verplanck, Philip L.

2005-01-01

The U.S. Geological Survey, in cooperation with the New Mexico Environment Department, is investigating the pre-mining ground-water chemistry at the Molycorp molybdenum mine in the Red River Valley, northern New Mexico. The primary approach is to determine the processes controlling ground-water chemistry at an unmined, off-site, proximal analog. The Straight Creek drainage basin, chosen for this purpose, consists of the same quartz-sericite-pyrite altered andesitic and rhyolitic volcanic rock of Tertiary age as the mine site. The weathered and rugged volcanic bedrock surface is overlain by heterogeneous debris-flow deposits that interfinger with alluvial deposits near the confluence of Straight Creek and the Red River. Pyritized rock in the upper part of the drainage basin is the source of acid rock drainage (pH 2.8-3.3) that infiltrates debris-flow deposits containing acidic ground water (pH 3.0-4.0) and bedrock containing water of circumneutral pH values (5.6-7.7). Eleven observation wells were installed in the Straight Creek drainage basin. The wells were completed in debris-flow deposits, bedrock, and interfingering debris-flow and Red River alluvial deposits. Chemical analyses of ground water from these wells, combined with chemical analyses of surface water, water-level data, and lithologic and geophysical logs, provided information used to develop an understanding of the processes contributing to the chemistry of ground water in the Straight Creek drainage basin. Surface- and ground-water samples were routinely collected for determination of total major cations and selected trace metals; dissolved major cations, selected trace metals, and rare-earth elements; anions and alkalinity; and dissolved-iron species. Rare-earth elements were determined on selected samples only. Samples were collected for determination of dissolved organic carbon, mercury, sulfur isotopic composition (34S and 18O of sulfate), and water isotopic composition (2H and 18O) during selected samplings. One set of ground-water samples was collected for helium-3/tritium and chlorofluorocarbon (CFC) age dating. Several lines of evidence indicate that surface water is the primary input to the Straight Creek ground-water system. Straight Creek streamflow and water levels in wells closest to the apex of the Straight Creek debris fan and closest to Straight Creek itself appear to respond to the same seasonal inputs. Oxygen and hydrogen isotopic compositions in Straight Creek surface water and ground water are similar, and concentrations of most dissolved constituents in most Straight Creek surface-water and shallow (debris-flow and alluvial) aquifer ground-water samples correlate strongly with sulfate (concentrations decrease linearly with sulfate in a downgradient direction). After infiltration of surface water, dilution along the flow path is the dominant mechanism controlling ground-water chemistry. However, concentrations of some constituents can be higher in ground water than can be accounted for by concentrations in Straight Creek surface water, and additional sources of these constituents must therefore be inferred. Constituents for which concentrations in ground water can be high relative to surface water include calcium, magnesium, strontium, silica, sodium, and potassium in ground water from debris-flow and alluvial aquifers and manganese, calcium, magnesium, strontium, sodium, and potassium in ground water from the bedrock aquifer. All ground water is a calcium sulfate type, often at or near gypsum saturation because of abundant gypsum in the aquifer material developed from co-existing calcite and pyrite mineralization. Calcite dissolution, the major buffering mechanism for bedrock aquifer ground water, also contributes to relatively higher calcium concentrations in some ground water. The main source of the second most abundant cation, magnesium, is probably dissolution of magnesium-rich carbonates or silicates. Strontium may also be

Health and environmental policy issues in Canada: the role of watershed management in sustaining clean drinking water quality at surface sources.

PubMed

Davies, John-Mark; Mazumder, Asit

2003-07-01

Sustaining clean and safe drinking water sources is increasingly becoming a priority because of global pollution. The means of attaining and maintaining clean drinking water sources requires effective policies that identify, document, and reduce watershed risks. These risks are defined by their potential impact to human health. Health and risk are, therefore, indelibly linked because they are in part defined by each other. Understanding pathogen ecology and identifying watershed sources remains a priority because of the associated acute risks. Surface water quality changes resulting from inputs of human waste, nutrients and chemicals are associated with higher drinking water risks. Nutrient input can increase primary production and the resulting increase of organic matter results in greater disinfection by-product formation or requires greater treatment intensity. Many drinking water disease outbreaks have resulted from breaches in treatment facilities, therefore, even with greater treatment intensity poor source water quality intrinsically has greater associated health risks. Government and international agencies play a critical role in developing policy. The goal of maintaining water supplies whose availability is maximized and risks are minimized (i.e. sustainable) should be a vital part of such policy. Health risks are discussed in the context of a multi-barrier perspective and it is concluded that both passive (protection) and active (prescriptive management) management is necessary for sustainability. Canadian aboriginal water systems, British Columbian water policy and US EPA policies are given as examples. The basis for developing effective policies includes a strong reliance on sound science and effective instrumentation with careful consideration of stakeholders' interests. Only with such directed policies can the future availability of clean drinking water sources be ensured.

Managing surface water inputs to reduce phosphorus loss from Cranberry farms

USDA-ARS?s Scientific Manuscript database

Calcium phosphate (Ca-P) precipitation holds great promise in the mitigation of dissolved phosphorus (DP) loss from cranberry bogs, with precipitated Ca-P potentially serving as a fertilizer source for the subsequent cranberry crop. We quantified Ca-P precipitation following calcite application to h...

SIMULATED CLIMATE CHANGE EFFECTS ON DISSOLVED OXYGEN CHARACTERISTICS IN ICE-COVERED LAKES. (R824801)

EPA Science Inventory

A deterministic, one-dimensional model is presented which simulates daily dissolved oxygen (DO) profiles and associated water temperatures, ice covers and snow covers for dimictic and polymictic lakes of the temperate zone. The lake parameters required as model input are surface ...

Nitrogen Control Through Decentralized Wastewater Treatment: Process Performance and Alternative Management Strategies

EPA Science Inventory

Decentralized or onsite wastewater treatment (OWT) systems have long been implicated in being a major source of N inputs to surface and ground waters and numerous regulatory bodies have promulgated strict total N (TN) effluent standards in N-sensitive areas. These standards, howe...

Effects of hypoxia on the response of fish to estrogen exposure

EPA Science Inventory

Natural and synthetic estrogens are common contaminants in surface waters and have the potential to affect reproduction in fish. Estrogens are likely to co-occur with low dissolved oxygen (DO) levels, which result from inputs of organic material in wastewater effluents or from an...

Thermal and Hydrologic Signatures of Soil Controls on Evaporation: A Combined Energy and Water Balance Approach with Implications for Remote Sensing of Evaporation

NASA Technical Reports Server (NTRS)

Salvucci, Guido D.

2000-01-01

The overall goal of this research is to examine the feasibility of applying a newly developed diagnostic model of soil water evaporation to large land areas using remotely sensed input parameters. The model estimates the rate of soil evaporation during periods when it is limited by the net transport resulting from competing effects of capillary rise and drainage. The critical soil hydraulic properties are implicitly estimated via the intensity and duration of the first stage (energy limited) evaporation, removing a major obstacle in the remote estimation of evaporation over large areas. This duration, or 'time to drying' (t(sub d)) is revealed through three signatures detectable in time series of remote sensing variables. The first is a break in soil albedo that occurs as a small vapor transmission zone develops near the surface. The second is a break in either surface to air temperature differences or in the diurnal surface temperature range, both of which indicate increased sensible heat flux (and/or storage) required to balance the decrease in latent heat flux. The third is a break in the temporal pattern of near surface soil moisture. Soil moisture tends to decrease rapidly during stage I drying (as water is removed from storage), and then become more or less constant during soil limited, or 'stage II' drying (as water is merely transmitted from deeper soil storage). The research tasks address: (1) improvements in model structure, including extensions to transpiration and aggregation over spatially variable soil and topographic landscape attributes; and (2) applications of the model using remotely sensed input parameters.

Thermal and Hydrologic Signatures of Soil Controls on Evaporation: A Combined Energy and Water Balance Approach with Implications for Remote Sensing of Evaporation

NASA Technical Reports Server (NTRS)

Salvucci, Guido D.

1997-01-01

The overall goal of this research is to examine the feasibility of applying a newly developed diagnostic model of soil water evaporation to large land areas using remotely sensed input parameters. The model estimates the rate of soil evaporation during periods when it is limited by the net transport resulting from competing effects of capillary rise and drainage. The critical soil hydraulic properties are implicitly estimated via the intensity and duration of the first stage (energy limited) evaporation, removing a major obstacle in the remote estimation of evaporation over large areas. This duration, or "time to drying" (t(sub d)), is revealed through three signatures detectable in time series of remote sensing variables. The first is a break in soil albedo that occurs as a small vapor transmission zone develops near the surface. The second is a break in either surface to air temperature differences or in the diurnal surface temperature range, both of which indicate increased sensible heat flux (and/or storage) required to balance the decrease in latent heat flux. The third is a break in the temporal pattern of near surface soil moisture. Soil moisture tends to decrease rapidly during stage 1 drying (as water is removed from storage), and then become more or less constant during soil limited, or "stage 2" drying (as water is merely transmitted from deeper soil storage). The research tasks address: (1) improvements in model structure, including extensions to transpiration and aggregation over spatially variable soil and topographic landscape attributes; and (2) applications of the model using remotely sensed input parameters.

Evidence for methane production by marine algae (Emiliana huxleyi) and its implication for the methane paradox in oxic waters

NASA Astrophysics Data System (ADS)

Lenhart, K.; Klintzsch, T.; Langer, G.; Nehrke, G.; Bunge, M.; Schnell, S.; Keppler, F.

2015-12-01

Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, frequently regional and temporal oversaturation of surface waters occurs. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the "oceanic methane paradox". In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two 13C-labelled carbon substrates, namely bicarbonate and a position-specific 13C-labelled methionine (R-S-13CH3). The CH4 production was 0.7 μg POC g-1 d-1, or 30 ng g-1 POC h-1. After supplementation of the cultures with the 13C labelled substrate, the isotope label was observed in headspace-CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that marine algae such as Emiliania huxleyi contribute to the observed spatial and temporal restricted CH4 oversaturation in ocean surface waters.

The role of nitrogen deposition in the recent nitrate decline in lakes and rivers in Northern Italy.

PubMed

Rogora, Michela; Arisci, Silvia; Marchetto, Aldo

2012-02-15

Deposition of inorganic nitrogen (N) in north-western Italy is around 20-25 kg N ha(-1)y(-1), and has remained constant during the last 30 years. This flux of N caused saturation of terrestrial catchments and increasing levels of nitrate (NO(3)) in surface waters. Recently, monitoring data for both rivers and lakes have shown a reversal in NO(3) trends. This change was widespread, affecting high-altitude lakes in the Alps and subalpine lakes and rivers, and occurred at almost the same time at all sites. The seasonal pattern of NO(3) concentrations in running waters has shown a change in the last few years, with a tendency towards slightly lower leaching of NO(3) during the growing season. Atmospheric input of N has also shown a recent decrease, mainly due to decreasing emissions and partly to the lower amount of precipitation occurring between 2003 and 2009. Surface waters are probably responding to these changing N inputs, but a further decrease of N deposition, especially reduced N, will be required to achieve full recovery from N saturation. Copyright © 2012 Elsevier B.V. All rights reserved.

Anthropogenic phosphorus (P) inputs to a river basin and their impacts on P fluxes along its upstream-downstream continuum

NASA Astrophysics Data System (ADS)

Zhang, Wangshou; Swaney, Dennis; Hong, Bongghi; Howarth, Robert

2017-04-01

Phosphorus (P) originating from anthropogenic sources as a pollutant of surface waters has been an environmental issue for decades because of the well-known role of P in eutrophication. Human activities, such as food production and rapid urbanization, have been linked to increased P inputs which are often accompanied by corresponding increases in riverine P export. However, uneven distributions of anthropogenic P inputs along watersheds from the headwaters to downstream reaches can result in significantly different contributions to the riverine P fluxes of a receiving water body. So far, there is still very little scientific understanding of anthropogenic P inputs and their impacts on riverine flux in river reaches along the upstream to downstream continuum. Here, we investigated P budgets in a series of nested watersheds draining into Hongze Lake of China, and developed a simple empirical function to describe the relationship between anthropogenic inputs and riverine TP fluxes. The results indicated that an average of 1.1% of anthropogenic P inputs are exported into rivers, with most of the remainder retained in the watershed landscape over the period studied. Fertilizer application was the main contributor of P loading to the lake (55% of total loads), followed by legacy P stock (30%), food and feed P inputs (12%) and non-food P inputs (4%). From 60% to 89% of the riverine TP loads generated from various locations within this basin were ultimately transported into the receiving lake of the downstream, with an average rate of 1.86 tons P km-1 retaining in the main stem of the inflowing river annually. Our results highlight that in-stream processes can significantly buffer the riverine P loading to the downstream receiving lake. An integrated P management strategy considering the influence of anthropogenic inputs and hydrological interactions is required to assess and optimize P management for protecting fresh waters.

Thermophysical effects of ointments in cold: an experimental study with a skin model.

PubMed

Lehmuskallio, E; Anttonen, H

1999-01-01

The use of emollients on the face is a traditional way to protect the skin against cold injuries in cold climate countries like Finland, but their preventive effect against frostbite has been questioned. The purpose of this investigation was to define the thermal insulation and occlusivity of ointments in cold by using a skin model with a sweating hot plate. The properties of four different emollients were studied in both dry and humid conditions simulating transepidermal water loss, sweating, and a combination of sweating and drying. The thermal insulation of ointments applied on a dry surface was minimal. Evaporation of water from an oil-in-water cream caused significant cooling for 40 min after its application. The diffusion of water through the applied emollients changed their thermal effects depending on their composition and on the amount of water. Low input of water increased and high input diminished slightly the thermal resistance of ointments. The minimal or even negative thermal insulation of emollients in varying conditions gives them at best only a negligible and at worst a disadvantageous physical effect against cold.

Roles of Fog and Topography in Redwood Forest Hydrology

NASA Astrophysics Data System (ADS)

Francis, E. J.; Asner, G. P.

2017-12-01

Spatial variability of water in forests is a function of both climatic gradients that control water inputs and topo-edaphic variation that determines the flows of water belowground, as well as interactions of climate with topography. Coastal redwood forests are hydrologically unique because they are influenced by coastal low clouds, or fog, that is advected onto land by a strong coastal-to-inland temperature difference. Where fog intersects the land surface, annual water inputs from summer fog drip can be greater than that of winter rainfall. In this study, we take advantage of mapped spatial gradients in forest canopy water storage, topography, and fog cover in California to better understand the roles and interactions of fog and topography in the hydrology of redwood forests. We test a conceptual model of redwood forest hydrology with measurements of canopy water content derived from high-resolution airborne imaging spectroscopy, topographic variables derived from high-resolution LiDAR data, and fog cover maps derived from NASA MODIS data. Landscape-level results provide insight into hydrological processes within redwood forests, and cross-site analyses shed light on their generality.

Problems in Assessment of the UV Penetration into Natural Waters from Space-based Measurements

NASA Technical Reports Server (NTRS)

Vasilkov, Alexander P.; Herman, Jay; Krotkov, Nickolay A.; Kahru, Mati; Mitchell, B. Greg; Hsu, Christina; Bhartia, P. K. (Technical Monitor)

2002-01-01

Satellite instruments currently provide global maps of surface UV (ultraviolet) irradiance by combining backscattered radiance data with radiative transfer models. The models are often limited by uncertainties in physical input parameters of the atmosphere and surface. Global mapping of the underwater UV irradiance creates further challenges for the models. The uncertainties in physical input parameters become more serious because of the presence of absorbing and scattering quantities caused by biological processes within the oceans. In this paper we summarize the problems encountered in the assessment of the underwater UV irradiance from space-based measurements, and propose approaches to resolve the problems. We have developed a radiative transfer scheme for computation of the UV irradiance in the atmosphere-ocean system. The scheme makes use of input parameters derived from satellite instruments such as TOMS (Total Ozone Mapping Spectrometer) and SeaWiFS (Sea-viewing Wide Field-of-view Sensor). The major problem in assessment of the surface UV irradiance is to accurately quantify the effects of clouds. Unlike the standard TOMS UV algorithm, we use the cloud fraction products available from SeaWiFS and MODIS (Moderate Resolution Imaging Spectrometer) to calculate instantaneous surface flux at the ocean surface. Daily UV doses can be calculated by assuming a model of constant cloudiness throughout the day. Both SeaWiFS and MODIS provide some estimates of seawater optical properties in the visible. To calculate the underwater UV flux the seawater optical properties must be extrapolated down to shorter wavelengths. Currently, the problem of accurate extrapolation of visible data down to the UV spectral range is not solved completely, and there are few available measurements. The major difficulty is insufficient correlation between photosynthetic and photoprotective pigments of phytoplankton absorbing in the visible and UV respectively. We propose to empirically parameterize seawater absorption in the UV on a basis of available data sets of bio-optical measurements from a variety of ocean waters. Another problem is the lack of reliable data on pure seawater absorption in the UV. Laboratory measurements of the UV absorption of both pure water and pure seawater are required.

Virtual mission stage I: Implications of a spaceborne surface water mission

NASA Astrophysics Data System (ADS)

Clark, E. A.; Alsdorf, D. E.; Bates, P.; Wilson, M. D.; Lettenmaier, D. P.

2004-12-01

The interannual and interseasonal variability of the land surface water cycle depend on the distribution of surface water in lakes, wetlands, reservoirs, and river systems; however, measurements of hydrologic variables are sparsely distributed, even in industrialized nations. Moreover, the spatial extent and storage variations of lakes, reservoirs, and wetlands are poorly known. We are developing a virtual mission to demonstrate the feasibility of observing surface water extent and variations from a spaceborne platform. In the first stage of the virtual mission, on which we report here, surface water area and fluxes are emulated using simulation modeling over three continental scale river basins, including the Ohio River, the Amazon River and an Arctic river. The Variable Infiltration Capacity (VIC) macroscale hydrologic model is used to simulate evapotranspiration, soil moisture, snow accumulation and ablation, and runoff and streamflow over each basin at one-eighth degree resolution. The runoff from this model is routed using a linear transfer model to provide input to a much more detailed flow hydraulics model. The flow hydraulics model then routes runoff through various channel and floodplain morphologies at a 250 m spatial and 20 second temporal resolution over a 100 km by 500 km domain. This information is used to evaluate trade-offs between spatial and temporal resolutions of a hypothetical high resolution spaceborne altimeter by synthetically sampling the resultant model-predicted water surface elevations.

Denitrification rates in marsh soils and hydrologic and water quality data for Northeast Creek and Bass Harbor Marsh watersheds, Mount Desert Island, Maine

USGS Publications Warehouse

Huntington, Thomas G.; Culbertson, Charles W.; Duff, John H.

2011-01-01

Nutrient enrichment from atmospheric deposition, agricultural activities, wildlife, and domestic sources is a concern at Acadia National Park because of the potential problem of water-quality degradation and eutrophication in estuaries. Water-quality degradation has been observed at the park's Bass Harbor Marsh estuary but minimal degradation is observed in Northeast Creek estuary. Previous studies at Acadia National Park have estimated nutrient inputs to estuaries from atmospheric deposition and surface-water runoff, and have identified shallow groundwater as an additional potential nutrient source. Previous studies at Acadia National Park have assumed that a certain fraction of the nitrogen input was removed through microbial denitrification, but rates of denitrification (natural or maximum potential) in marsh soils have not been determined. The U.S. Geological Survey, in cooperation with Acadia National Park, measured in situ denitrification rates in marsh soils in Northeast Creek and Bass Harbor Marsh watersheds during the summer seasons of 2008 and 2009. Denitrification was measured under ambient conditions and following inorganic nitrogen and glucose additions. Laboratory incubations of marsh soils with and without acetylene were conducted to determine average ratios of nitrous oxide (N2O) to nitrogen (N2) produced during denitrification. Surface water and groundwater samples were analyzed for nutrients, specific conductance, temperature, and dissolved oxygen. Water level was recorded continuously during the growing season in Fresh Meadow Marsh in the Northeast Creek Watershed.

Impact of Uncertainties in Meteorological Forcing Data and Land Surface Parameters on Global Estimates of Terrestrial Water Balance Components

NASA Astrophysics Data System (ADS)

Nasonova, O. N.; Gusev, Ye. M.; Kovalev, Ye. E.

2009-04-01

Global estimates of the components of terrestrial water balance depend on a technique of estimation and on the global observational data sets used for this purpose. Land surface modelling is an up-to-date and powerful tool for such estimates. However, the results of modelling are affected by the quality of both a model and input information (including meteorological forcing data and model parameters). The latter is based on available global data sets containing meteorological data, land-use information, and soil and vegetation characteristics. Now there are a lot of global data sets, which differ in spatial and temporal resolution, as well as in accuracy and reliability. Evidently, uncertainties in global data sets will influence the results of model simulations, but to which extent? The present work is an attempt to investigate this issue. The work is based on the land surface model SWAP (Soil Water - Atmosphere - Plants) and global 1-degree data sets on meteorological forcing data and the land surface parameters, provided within the framework of the Second Global Soil Wetness Project (GSWP-2). The 3-hourly near-surface meteorological data (for the period from 1 July 1982 to 31 December 1995) are based on reanalyses and gridded observational data used in the International Satellite Land-Surface Climatology Project (ISLSCP) Initiative II. Following the GSWP-2 strategy, we used a number of alternative global forcing data sets to perform different sensitivity experiments (with six alternative versions of precipitation, four versions of radiation, two pure reanalysis products and two fully hybridized products of meteorological data). To reveal the influence of model parameters on simulations, in addition to GSWP-2 parameter data sets, we produced two alternative global data sets with soil parameters on the basis of their relationships with the content of clay and sand in a soil. After this the sensitivity experiments with three different sets of parameters were performed. As a result, 16 variants of global annual estimates of water balance components were obtained. Application of alternative data sets on radiation, precipitation, and soil parameters allowed us to reveal the influence of uncertainties in input data on global estimates of water balance components.

Simulations of Water Migration in the Lunar Exosphere

NASA Astrophysics Data System (ADS)

Hurley, D.; Benna, M.; Mahaffy, P. R.; Elphic, R. C.; Goldstein, D. B.

2014-12-01

We perform modeling and analysis of water in the lunar exosphere. There were two controlled experiments of water interactions with the surface of the Moon observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE) Neutral Mass Spectrometer (NMS). The Chang'e 3 landing on the Moon on 14 Dec 2013 putatively sprayed ~120 kg of water on the surface on the Moon at a mid-morning local time. Observations by LADEE near the noon meridian on six of the orbits in the 24 hours following the landing constrain the propagation of water vapor. Further, on 4 Apr 2014, LADEE's Orbital Maintenance Manuever (OMM) #21 sprayed the surface of the Moon with an estimated 0.73 kg of water in the pre-dawn sector. Observations of this maneuver and later in the day constrain the adsorption and release at dawn of adsorbed materials. Using the Chang'e 3 exhaust plume and LADEE's OMM-21 as control experiments, we set limits to the adsorption and thermalization of water with lunar regolith. This enables us to predict the efficiency of the migration of water as a delivery mechanism to the lunar poles. Then we simulate the migration of water through the lunar exosphere using the rate of sporadic inputs from meteoritic sources (Benna et al., this session). Simulations predict the amount of water adsorbed to the surface of the Moon and the effective delivery rate to the lunar polar cold traps.

Estimation water vapor content using the mixing ratio method and validated with the ANFIS PWV model

NASA Astrophysics Data System (ADS)

Suparta, W.; Alhasa, K. M.; Singh, M. S. J.

2017-05-01

This study reported the comparison between water vapor content, the surface meteorological data (pressure, temperature, and relative humidity), and precipitable water vapor (PWV) produced by PWV from adaptive neuro fuzzy inference system (ANFIS) for areas in the Universiti Kebangsaan Malaysia Bangi (UKMB) station. The water vapor content value was estimated with mixing ratio method and the surface meteorological data as the parameter inputs. The accuracy of water vapor content was validated with PWV from ANFIS PWV model for the period of 20-23 December 2016. The result showed that the water vapor content has a similar trend with the PWV which produced by ANFIS PWV model (r = 0.975 at the 99% confidence level). This indicates that the water vapor content that obtained with mixing ratio agreed very well with the ANFIS PWV model. In addition, this study also found, the pattern of water vapor content and PWV have more influenced by the relative humidity.

Distribution and evolution of sterols and aliphatic hydrocarbons in dated marine sediment cores from the Cabo Frio upwelling region, SW Atlantic, Brazil.

PubMed

Lourenço, Rafael André; Martins, César C; Taniguchi, Satie; Mahiques, Michel Michaelovitch; Montone, Rosalinda Carmela; Magalhães, Caio Augusto; Bícego, Márcia Caruso

2017-08-01

We report the distribution of selected lipid biomarkers specifically sterols and aliphatic hydrocarbons in sediment cores from Cabo Frio, SW Atlantic continental shelf, Brazil, corresponding approximately to the last 700 years. In the Cabo Frio region, a costal upwelling occurs as a quasi-seasonal phenomenon characterized by nutrient-rich bottom waters that intrude on the continental shelf and promote relatively high biological productivity compared to other Brazilian continental shelf areas. The results for sterols indicate the predominance of organic matter (OM) inputs related to marine organisms, mainly plankton, in all of the cores along the time scale studied. Principal component analyses show three different groups of variables, which may be associated with (i) the more effective intrusion of the nutrient-rich South Atlantic Central Water, resulting in the increase of marine lipid biomarkers such as sterols and short-chain n-alkanes; (ii) the influence of the Coastal Water with higher surface water temperature and subsequently lower primary productivity; and (iii) OM characterized by high total organic carbon and long-chain n-alkanes related to an allochthonous source. Relatively high concentrations of sterols and n-alkanes between 1450 and 1700 AD, chronologically associated with the Little Ice Age, suggest a period associated with changes in the local input of specific sources of these compounds. The concentrations of lipid biomarkers vary over core depth, but this does not suggest a notably high or low intensity of upwelling processes. It is possible that the climatic and sea surface temperature changes reported in previous studies did not affect the input of the sedimentary lipid biomarkers analyzed here.

The NASA/GEWEX Surface Radiation Budget: Integrated Data Product With Reprocessed Radiance, Cloud, and Meteorology Inputs

NASA Astrophysics Data System (ADS)

Stackhouse, P. W.; Gupta, S. K.; Cox, S. J.; Mikovitz, J. C.; Zhang, T.

2015-12-01

The NASA/GEWEX Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. Spatial resolution is 1 degree. The current release 3.0 (available at gewex-srb.larc.nasa.gov) uses the International Satellite Cloud Climatology Project (ISCCP) DX product for pixel level radiance and cloud information. This product is subsampled to 30 km. ISCCP is currently recalibrating and recomputing their entire data series, to be released as the H product, at 10km resolution. The ninefold increase in pixel number will allow SRB a higher resolution gridded product (e.g. 0.5 degree), as well as the production of pixel-level fluxes. Other key input improvements include a detailed aerosol history using the Max Planck Institut Aerosol Climatology (MAC), temperature and moisture profiles from HIRS, and new topography, surface type, and snow/ice. At the time of abstract submission, results from the year 2007 have been produced. More years will be added as ISCCP reprocessing occurs. Here we present results for the improved GEWEX Shortwave and Longwave algorithm (GSW and GLW) with new ISCCP data, the various other improved input data sets and the incorporation of many additional internal SRB model improvements. Improvements in GSW include an expansion of the number of wavelength bands from five to eighteen, and the inclusion of ice cloud vs. water cloud radiative transfer. The SRB data produced will be released as part of the Release 4.0 Integrated Product, recognizing the interdependence of the radiative fluxes with other GEWEX products providing estimates of the Earth's global water and energy cycle (I.e., ISCCP, SeaFlux, LandFlux, NVAP, etc.).

A Consistent Treatment of Microwave Emissivity and Radar Backscatter for Retrieval of Precipitation over Water Surfaces

NASA Technical Reports Server (NTRS)

Munchak, S. Joseph; Meneghini, Robert; Grecu, Mircea; Olson, William S.

2016-01-01

The Global Precipitation Measurement satellite's Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR) are designed to provide the most accurate instantaneous precipitation estimates currently available from space. The GPM Combined Algorithm (CORRA) plays a key role in this process by retrieving precipitation profiles that are consistent with GMI and DPR measurements; therefore, it is desirable that the forward models in CORRA use the same geophysical input parameters. This study explores the feasibility of using internally consistent emissivity and surface backscatter cross-sectional (sigma(sub 0)) models for water surfaces in CORRA. An empirical model for DPR Ku and Ka sigma(sub 0) as a function of 10m wind speed and incidence angle is derived from GMI-only wind retrievals under clear-sky conditions. This allows for the sigma(sub 0) measurements, which are also influenced by path-integrated attenuation (PIA) from precipitation, to be used as input to CORRA and for wind speed to be retrieved as output. Comparisons to buoy data give a wind rmse of 3.7 m/s for Ku+GMI and 3.2 m/s for Ku+Ka+GMI retrievals under precipitation (compared to 1.3 m/s for clear-sky GMI-only), and there is a reduction in bias from GANAL background data (-10%) to the Ku+GMI (-3%) and Ku+Ka+GMI (-5%) retrievals. Ku+GMI retrievals of precipitation increase slightly in light (less than 1 mm/h) and decrease in moderate to heavy precipitation (greater than 1 mm/h). The Ku+Ka+GMI retrievals, being additionally constrained by the Ka reflectivity, increase only slightly in moderate and heavy precipitation at low wind speeds (less than 5 m/s) relative to retrievals using the surface reference estimate of PIA as input.

Improved ground hydrology calculations for global climate models (GCMs) - Soil water movement and evapotranspiration

NASA Technical Reports Server (NTRS)

Abramopoulos, F.; Rosenzweig, C.; Choudhury, B.

1988-01-01

A physically based ground hydrology model is presented that includes the processes of transpiration, evaporation from intercepted precipitation and dew, evaporation from bare soil, infiltration, soil water flow, and runoff. Data from the Goddard Institute for Space Studies GCM were used as inputs for off-line tests of the model in four 8 x 10 deg regions, including Brazil, Sahel, Sahara, and India. Soil and vegetation input parameters were caculated as area-weighted means over the 8 x 10 deg gridbox; the resulting hydrological quantities were compared to ground hydrology model calculations performed on the 1 x 1 deg cells which comprise the 8 x 10 deg gridbox. Results show that the compositing procedure worked well except in the Sahel, where low soil water levels and a heterogeneous land surface produce high variability in hydrological quantities; for that region, a resolution better than 8 x 10 deg is needed.

[Model simulation of the transportation, transformation and accumulation of synthetic musks in soils input through recycle water irrigation].

PubMed

Wang, Mei-E; Chen, Wei-Ping; Jiao, Wen-Tao

2012-12-01

Environmental pollution of synthetic musks HHCB and AHTN, one type of PPCPs, have been attracted great attentions in latest years. One of the main input pathways of HHCB/AHTN to soils is reclaimed water irrigation. In this study, we monitored HHCB and AHTN in soils irrigated by reclaimed water and irrigation water and modeled the transportation and accumulation of HHCB and AHTN in soils using HYDRUS-1D. Results showed that concentrations of HHCB and AHTN in soils irrigated by recycling water were 5 times higher than tape water irrigation soils although both of the concentrations are trace. The temporal increase of accumulation was exponential when lgK(oc) value was 3.44, while linear when lgK(oc) were 4.12 and 4.86. Changes of half life of HHCB/AHTN did not affect their accumulation in surface soils. The downward transportation of HHCB and AHTN under recycling water irrigation was very slow. After 40 years of irrigation, it could only 53 cm at most favored conditionals. The downward movement was greatly impacted by the lgK(oc) values. The dissipation of those two synthetic musks through biological degradation and plant uptake were tiny. The highest dissipation rate through biological degradation and plant uptake was only 7.69% of the total input by reclaimed water irrigation after 40 years. The dissipation rate was increased with the decrease of lgK(oc) values and irrigation time. Results of this work may offer base for accurate assessing the ecological risks of HHCB and AHTN in soils caused by reclaimed water irrigation.

DOTAGWA: A CASE STUDY IN WEB-BASED ARCHITECTURES FOR CONNECTING SURFACE WATER MODELS TO SPATIALLY ENABLED WEB APPLICATIONS

EPA Science Inventory

The Automated Geospatial Watershed Assessment (AGWA) tool is a desktop application that uses widely available standardized spatial datasets to derive inputs for multi-scale hydrologic models (Miller et al., 2007). The required data sets include topography (DEM data), soils, clima...

Plant Growth and Phosphorus Uptake of Three Riparian Grass Species

USDA-ARS?s Scientific Manuscript database

Riparian buffers can significantly reduce sediment-bound phosphorus (P) entering surface water, but control of dissolved P inputs is more challenging. Because plant roots remove P from soil solution, it follows that plant uptake will reduce dissolved P losses. We evaluated P uptake of smooth bromegr...

Watershed Nitrogen Modeling: Benefits of Diverse Approaches Using a Case Study from New York State

EPA Science Inventory

Watershed-scale models have evolved as an important tool for estimating the sources, transformation, and transport of contaminants to surface water systems. A wide variety of modeling approaches exist for estimating inputs, fate, and transport of constituents but most are broadl...

Development of a classical force field for the oxidized Si surface: application to hydrophilic wafer bonding.

PubMed

Cole, Daniel J; Payne, Mike C; Csányi, Gábor; Spearing, S Mark; Colombi Ciacchi, Lucio

2007-11-28

We have developed a classical two- and three-body interaction potential to simulate the hydroxylated, natively oxidized Si surface in contact with water solutions, based on the combination and extension of the Stillinger-Weber potential and of a potential originally developed to simulate SiO(2) polymorphs. The potential parameters are chosen to reproduce the structure, charge distribution, tensile surface stress, and interactions with single water molecules of a natively oxidized Si surface model previously obtained by means of accurate density functional theory simulations. We have applied the potential to the case of hydrophilic silicon wafer bonding at room temperature, revealing maximum room temperature work of adhesion values for natively oxidized and amorphous silica surfaces of 97 and 90 mJm(2), respectively, at a water adsorption coverage of approximately 1 ML. The difference arises from the stronger interaction of the natively oxidized surface with liquid water, resulting in a higher heat of immersion (203 vs 166 mJm(2)), and may be explained in terms of the more pronounced water structuring close to the surface in alternating layers of larger and smaller densities with respect to the liquid bulk. The computed force-displacement bonding curves may be a useful input for cohesive zone models where both the topographic details of the surfaces and the dependence of the attractive force on the initial surface separation and wetting can be taken into account.

Nanotexturing of polystyrene surface in fluorocarbon plasmas: from sticky to slippery superhydrophobicity.

PubMed

Mundo, Rosa Di; Palumbo, Fabio; d'Agostino, Riccardo

2008-05-06

In this work plasma etching processes have been studied to roughen and fluorinate polystyrene surface as an easy method to achieve a superhydrophobic slippery character. Radiofrequency discharges have been fed with CF(4)/O(2) mixtures and the effect of the O(2):CF(4) ratio, the input power, and the treatment duration have been investigated in terms of wettability, with focus on sliding performances. For this purpose, surface morphological variations, evaluated by means of scanning electron microscopy and atomic force microscopy, together with the chemical assessment by X-ray photoelectron spectroscopy, have been correlated with water contact angle hysteresis and volume resolved sliding angle measurements. Results indicate that by increasing the height and decreasing the density of the structures formed by etching, within a tailored range, a transition from sticky to slippery superhydrophobicity occurs. A short treatment time (5 min) is sufficient to obtain such an effect, provided that a high power input is utilized. Optimized surfaces show a unaltered transparency to visible light according to the low roughness produced.

A comprehensive surface-groundwater flow model

NASA Astrophysics Data System (ADS)

Arnold, Jeffrey G.; Allen, Peter M.; Bernhardt, Gilbert

1993-02-01

In this study, a simple groundwater flow and height model was added to an existing basin-scale surface water model. The linked model is: (1) watershed scale, allowing the basin to be subdivided; (2) designed to accept readily available inputs to allow general use over large regions; (3) continuous in time to allow simulation of land management, including such factors as climate and vegetation changes, pond and reservoir management, groundwater withdrawals, and stream and reservoir withdrawals. The model is described, and is validated on a 471 km 2 watershed near Waco, Texas. This linked model should provide a comprehensive tool for water resource managers in development and planning.

Water balance of rice plots under three different water treatments: monitoring activity and experimental results

NASA Astrophysics Data System (ADS)

Chiaradia, Enrico Antonio; Romani, Marco; Facchi, Arianna; Gharsallah, Olfa; Cesari de Maria, Sandra; Ferrari, Daniele; Masseroni, Daniele; Rienzner, Michele; Battista Bischetti, Gian; Gandolfi, Claudio

2014-05-01

In the agricultural seasons 2012 and 2013, a broad monitoring activity was carried out at the Rice Research Centre of Ente Nazionale Risi (CRR-ENR) located in Castello d'Agogna (PV, Italy) with the purpose of comparing the water balance components of paddy rice (Gladio cv.) under different water regimes and assessing the possibility of reducing the high water inputs related to the conventional practice of continuous submergence. The experiments were laid out in six plots of about 20 m x 80 m each, with two replicates for each of the following water regimes: i) continuous flooding with wet-seeded rice (FLD), ii) continuous flooding from around the 3-leaf stage with dry-seeded rice (3L-FLD), and iii) surface irrigation every 7-10 days with dry-seeded rice (IRR). One out of the two replicates of each treatment was instrumented with: water inflow and outflow meters, set of piezometers, set of tensiometers and multi-sensor moisture probes. Moreover, an eddy covariance station was installed on the bund between the treatments FLD and IRR. Data were automatically recorded and sent by a wireless connection to a PC, so as to be remotely controlled thanks to the development of a Java interface. Furthermore, periodic measurements of crop biometric parameters (LAI, crop height and rooting depth) were performed in both 2012 and 2013 (11 and 14 campaigns respectively). Cumulative water balance components from dry-seeding (3L-FLD and IRR), or flooding (FLD), to harvest were calculated for each plot by either measurements (i.e. rainfall, irrigation and surface drainage) or estimations (i.e. difference in the field water storage, evaporation from both the soil and the water surface and transpiration), whereas the sum of percolation and capillary rise (i.e. the 'net percolation') was obtained as the residual term of the water balance. Incidentally, indices of water application efficiency (evapotranspiration over net water input) and water productivity (grain production over net water input) were calculated for each treatment. The outcomes show that the water application efficiencies of all treatments were higher in 2013 than in 2012 (by 23%, 25% and 4% for FLD, 3L-FLD, and IRR respectively). These results could be ascribed to the higher groundwater level observed in 2013 (about 10-15 cm closer to the soil surface), likely due to the conversion of the field beyond the monitored plots from soybean to flooded rice. Moreover, a small increase of the water application efficiency of 3L-FLD was found if compared to FLD (3% on average), while the water application efficiency of IRR was, on average, higher by 67% compared to FLD. The good performance of IRR is related to lower percolation rates and a relevant contribution of capillary rise due to the shallow groundwater table maintained by the continuous submergence of the surrounding paddy fields. The performed experiment highlighted that significant improvement in the water use efficiency at the field scale can be achieved. However, a widespread adoption of water regimes different from continuous flooding should be carefully evaluated by a larger-scale approach since a consequent drop in the groundwater table depth could have repercussions on the potential gains themselves.

Comparative Risk Assessment of spill response options for a deepwater oil well blowout: Part 1. Oil spill modeling.

PubMed

French-McCay, Deborah; Crowley, Deborah; Rowe, Jill J; Bock, Michael; Robinson, Hilary; Wenning, Richard; Walker, Ann Hayward; Joeckel, John; Nedwed, Tim J; Parkerton, Thomas F

2018-06-01

Oil spill model simulations of a deepwater blowout in the Gulf of Mexico De Soto Canyon, assuming no intervention and various response options (i.e., subsea dispersant injection SSDI, in addition to mechanical recovery, in-situ burning, and surface dispersant application) were compared. Predicted oil fate, amount and area of surfaced oil, and exposure concentrations in the water column above potential effects thresholds were used as inputs to a Comparative Risk Assessment to identify response strategies that minimize long-term impacts. SSDI reduced human and wildlife exposure to volatile organic compounds; dispersed oil into a large water volume at depth; enhanced biodegradation; and reduced surface water, nearshore and shoreline exposure to floating oil and entrained/dissolved oil in the upper water column. Tradeoffs included increased oil exposures at depth. However, since organisms are less abundant below 200 m, results indicate that overall exposure of valued ecosystem components was minimized by use of SSDI. Copyright © 2018 Elsevier Ltd. All rights reserved.

HCMM energy budget data as a model input for assessing regions of high potential groundwater pollution

NASA Technical Reports Server (NTRS)

Moore, D. G. (Principal Investigator); Heilman, J.; Beutler, G.

1978-01-01

The author has identified the following significant results. In early April 1978, heavy spring runoff from snowmelt caused significant flooding along a portion of the Big Sioux River Basin in southeastern South Dakota. The flooded area was visible from surrounding areas on a May 15 HCMM IR test image. On May 15, the flood waters had receded but an area of anomalous residual high soil moisture remained. The high soil moisture area was not visible on a HCMM day visible test image of the same scene, or on LANDSAT imagery. To evaluate the effect of water table depth on surface temperatures, thermal scanner data collected on September 5 and 6, 1978 at approximate HCMM overpass times at an altitude of 3650 m were analyzed. Apparent surface temperatures measured by the scanner included emittance contributions from soil surface and the land cover. Results indicated that the shallow water tables produced a damping of the amplitude of the diurnal surface temperature wave.

ORCHIDEE-MICT (v8.4.1), a land surface model for the high latitudes: model description and validation

NASA Astrophysics Data System (ADS)

Guimberteau, Matthieu; Zhu, Dan; Maignan, Fabienne; Huang, Ye; Yue, Chao; Dantec-Nédélec, Sarah; Ottlé, Catherine; Jornet-Puig, Albert; Bastos, Ana; Laurent, Pierre; Goll, Daniel; Bowring, Simon; Chang, Jinfeng; Guenet, Bertrand; Tifafi, Marwa; Peng, Shushi; Krinner, Gerhard; Ducharne, Agnès; Wang, Fuxing; Wang, Tao; Wang, Xuhui; Wang, Yilong; Yin, Zun; Lauerwald, Ronny; Joetzjer, Emilie; Qiu, Chunjing; Kim, Hyungjun; Ciais, Philippe

2018-01-01

The high-latitude regions of the Northern Hemisphere are a nexus for the interaction between land surface physical properties and their exchange of carbon and energy with the atmosphere. At these latitudes, two carbon pools of planetary significance - those of the permanently frozen soils (permafrost), and of the great expanse of boreal forest - are vulnerable to destabilization in the face of currently observed climatic warming, the speed and intensity of which are expected to increase with time. Improved projections of future Arctic and boreal ecosystem transformation require improved land surface models that integrate processes specific to these cold biomes. To this end, this study lays out relevant new parameterizations in the ORCHIDEE-MICT land surface model. These describe the interactions between soil carbon, soil temperature and hydrology, and their resulting feedbacks on water and CO2 fluxes, in addition to a recently developed fire module. Outputs from ORCHIDEE-MICT, when forced by two climate input datasets, are extensively evaluated against (i) temperature gradients between the atmosphere and deep soils, (ii) the hydrological components comprising the water balance of the largest high-latitude basins, and (iii) CO2 flux and carbon stock observations. The model performance is good with respect to empirical data, despite a simulated excessive plant water stress and a positive land surface temperature bias. In addition, acute model sensitivity to the choice of input forcing data suggests that the calibration of model parameters is strongly forcing-dependent. Overall, we suggest that this new model design is at the forefront of current efforts to reliably estimate future perturbations to the high-latitude terrestrial environment.

Utility of a Two-source Energy Balance Approach for Daily Mapping of Landsat-scale Fluxes Over Irrigated Agriculture in a Desert Environment

NASA Astrophysics Data System (ADS)

Houborg, R.; McCabe, M. F.; Rosas Aguilar, J.; Anderson, M. C.; Hain, C.

2014-12-01

The Middle East and North Africa (MENA) region is an area characterized by limited fresh water resources, an often inefficient use of these, and relatively poor in-situ monitoring as a result of sparse meteorological observations. Enhanced satellite-based monitoring systems are needed for aiding local water resource and agricultural management activities in these data poor arid environments. A multi-sensor and multi-scale land-surface flux monitoring capacity is being implemented over parts of MENA in order to provide meaningful decision support at relevant spatiotemporal scales. The integrated modeling system uses the Atmosphere-Land Exchange Inverse (ALEXI) model and associated flux disaggregation scheme (DisALEXI), and the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) in conjunction with model reanalysis data and remotely sensed data from polar orbiting (Landsat and MODIS; MODerate resolution Imaging Spectroradiometer) and geostationary (MSG; Meteosat Second Generation) satellite platforms to facilitate daily estimates of land surface fluxes down to sub-field scale (i.e. 30 m). Within this modeling system, thermal infrared satellite data provide information about the sub-surface moisture status and plant stress, obviating the need for precipitation input and error-prone soil surface characterizations. In this study, the integrated ALEXI-DisALEXI-STARFM framework is applied over an irrigated agricultural region in Saudi Arabia, and the daily estimates of Landsat scale water, energy and carbon fluxes are evaluated against available flux tower observations and other independent in-situ and satellite-based records. The study addresses the challenges associated with time-continuous sub-field scale mapping of land-surface fluxes in a harsh desert environment, and looks into the optimization of model descriptions and parameterizations and meteorological forcing and vegetation inputs for application over these regions.

Estimating the volume of supra-glacial melt lakes across Greenland: A study of uncertainties derived from multi-platform water-reflectance models

NASA Astrophysics Data System (ADS)

Cordero-Llana, L.; Selmes, N.; Murray, T.; Scharrer, K.; Booth, A. D.

2012-12-01

Large volumes of water are necessary to propagate cracks to the glacial bed via hydrofractures. Hydrological models have shown that lakes above a critical volume can supply the necessary water for this process, so the ability to measure water depth in lakes remotely is important to study these processes. Previously, water depth has been derived from the optical properties of water using data from high resolution optical satellite images, as such ASTER, (Advanced Spaceborne Thermal Emission and Reflection Radiometer), IKONOS and LANDSAT. These studies used water-reflectance models based on the Bouguer-Lambert-Beer law and lack any estimation of model uncertainties. We propose an optimized model based on Sneed and Hamilton's (2007) approach to estimate water depths in supraglacial lakes and undertake a robust analysis of the errors for the first time. We used atmospherically-corrected data from ASTER and MODIS data as an input to the water-reflectance model. Three physical parameters are needed: namely bed albedo, water attenuation coefficient and reflectance of optically-deep water. These parameters were derived for each wavelength using standard calibrations. As a reference dataset, we obtained lake geometries using ICESat measurements over empty lakes. Differences between modeled and reference depths are used in a minimization model to obtain parameters for the water-reflectance model, yielding optimized lake depth estimates. Our key contribution is the development of a Monte Carlo simulation to run the water-reflectance model, which allows us to quantify the uncertainties in water depth and hence water volume. This robust statistical analysis provides better understanding of the sensitivity of the water-reflectance model to the choice of input parameters, which should contribute to the understanding of the influence of surface-derived melt-water on ice sheet dynamics. Sneed, W.A. and Hamilton, G.S., 2007: Evolution of melt pond volume on the surface of the Greenland Ice Sheet. Geophysical Research Letters, 34, 1-4.

Soil Water and Temperature System (SWATS) Instrument Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, David R.

2016-04-01

The soil water and temperature system (SWATS) provides vertical profiles of soil temperature, soil-water potential, and soil moisture as a function of depth below the ground surface at hourly intervals. The temperature profiles are measured directly by in situ sensors at the Central Facility and many of the extended facilities of the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) site. The soil-water potential and soil moisture profiles are derived from measurements of soil temperature rise in response to small inputs of heat. Atmospheric scientists use the data in climate models tomore » determine boundary conditions and to estimate the surface energy flux. The data are also useful to hydrologists, soil scientists, and agricultural scientists for determining the state of the soil.« less

Coupled Spatiotemporal Dynamics of Microbial Community Ecology, Biogeochemistry, and Hydrologic Mixing

NASA Astrophysics Data System (ADS)

Stegen, J.; Johnson, T. C.; Fredrickson, J.; Wilkins, M.; Konopka, A.; Nelson, W.; Arntzen, E.; Chrisler, W.; Chu, R. K.; Fansler, S.; Kennedy, D.; Resch, T.; Tfaily, M. M.

2015-12-01

The hyporheic zone (HZ) is a critical ecosystem component that links terrestrial, surface water, and groundwater ecosystems. A dominant feature of the HZ is groundwater-surface water mixing and the input of terrestrially—as well as aquatically—derived organic carbon. In many systems the HZ has a relatively small spatial extent, but in larger riverine systems groundwater-surface water mixing can occur 100s of meters beyond the surface water shoreline; we consider these more distal locations to be within the 'subsurface interaction zone' (SIZ) as they are beyond the traditional HZ. Microbial communities in the HZ and SIZ drive biogeochemical processes in these system components, yet relatively little is known about the ecological processes that drive HZ and SIZ microbial communities. Here, we applied ecological theory, aqueous biogeochemistry, DNA sequencing, and ultra-high resolution organic carbon profiling to field samples collected through space (400m spatial extent) and time (7 month temporal extent) within the Hanford Site 300 Area. These data streams were integrated to evaluate how the influence of groundwater-surface water mixing on microbial communities changes when moving from the HZ to the broader SIZ. Our results indicate that groundwater-surface water mixing (i) consistently stimulated heterotrophic respiration, but only above a threshold of surface water intrusion, (ii) did not stimulate denitrification, (iii) caused deterministic shifts in HZ microbial communities due to changes in organic carbon composition, and (iv) did not cause shifts in SIZ microbial communities. These results suggest that microbial communities and the biogeochemical processes they drive are impacted by groundwater-surface water mixing primarily in the HZ and to a lesser extent in the SIZ.

Managing agricultural phosphorus for water quality: lessons from the USA and China.

PubMed

Sharpley, Andrew; Wang, Xiaoyan

2014-09-01

The accelerated eutrophication of freshwaters and to a lesser extent some coastal waters is primarily driven by phosphorus (P) inputs. While efforts to identify and limit point source inputs of P to surface waters have seen some success, nonpoint sources remain difficult to identify, target, and remediate. As further improvements in wastewater treatment technologies becomes increasingly costly, attention has focused more on nonpoint source reduction, particularly the role of agriculture. This attention was heightened over the last 10 to 20 years by a number of highly visible cases of nutrient-related water quality degradation; including the Lake Taihu, Baltic Sea, Chesapeake Bay, and Gulf of Mexico. Thus, there has been a shift to targeted management of critical sources of P loss. In both the U.S. and China, there has been an intensification of agricultural production systems in certain areas concentrate large amounts of nutrients in excess of local crop and forage needs, which has increased the potential for P loss from these areas. To address this, innovative technologies are emerging that recycle water P back to land as fertilizer. For example, in the watershed of Lake Taihu, China one of the largest surface fresh waters for drinking water supply in China, local governments have encouraged innovation and various technical trials to harvest harmful algal blooms and use them for bio-gas, agricultural fertilizers, and biofuel production. In any country, however, the economics of remediation will remain a key limitation to substantial changes in agricultural production. Copyright © 2014. Published by Elsevier B.V.

A digital model for planning water management at Benton Lake National Wildlife Refuge, west-central Montana

USGS Publications Warehouse

Nimick, David A.; McCarthy, Peter M.; Fields, Vanessa

2011-01-01

Benton Lake National Wildlife Refuge is an important area for waterfowl production and migratory stopover in west-central Montana. Eight wetland units covering about 5,600 acres are the essential features of the refuge. Water availability for the wetland units can be uncertain owing to the large natural variations in precipitation and runoff and the high cost of pumping supplemental water. The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, has developed a digital model for planning water management. The model can simulate strategies for water transfers among the eight wetland units and account for variability in runoff and pumped water. This report describes this digital model, which uses a water-accounting spreadsheet to track inputs and outputs to each of the wetland units of Benton Lake National Wildlife Refuge. Inputs to the model include (1) monthly values for precipitation, pumped water, runoff, and evaporation; (2) water-level/capacity data for each wetland unit; and (3) the pan-evaporation coefficient. Outputs include monthly water volume and flooded surface area for each unit for as many as 5 consecutive years. The digital model was calibrated by comparing simulated and historical measured water volumes for specific test years.

Hydrologic and Water-Quality Conditions During Restoration of the Wood River Wetland, Upper Klamath River Basin, Oregon, 2003-05

USGS Publications Warehouse

Carpenter, Kurt D.; Snyder, Daniel T.; Duff, John H.; Triska, Frank J.; Lee, Karl K.; Avanzino, Ronald J.; Sobieszczyk, Steven

2009-01-01

Restoring previously drained wetlands is a strategy currently being used to improve water quality and decrease nutrient loading into Upper Klamath Lake, Oregon. In this 2003-05 study, ground- and surface-water quality and hydrologic conditions were characterized in the Wood River Wetland. Nitrogen and phosphorus levels, primarily as dissolved organic nitrogen and ammonium (NH4) and soluble reactive phosphorus (SRP), were high in surface waters. Dissolved organic carbon concentrations also were elevated in surface water, with median concentrations of 44 and 99 milligrams of carbon per liter (mg-C/L) in the North and South Units of the Wood River Wetland, respectively, reaching a maximum of 270 mg-C/L in the South Unit in late autumn. Artesian well water produced NH4 and SRP concentrations of about 6,000 micrograms per liter (ug/L), and concentrations of 36,500 ug-N/L NH4 and 4,110 ug-P/L SRP in one 26-28 ft deep piezometer well. Despite the high ammonium concentrations, the nitrate levels were moderate to low in wetland surface and ground waters. The surface-water concentrations of NH4 and SRP increased in spring and summer, outpacing those for chloride (a conservative tracer), indicative of evapoconcentration. In-situ chamber experiments conducted in June and August 2005 indicated a positive flux of NH4 and SRP from the wetland sediments. Potential sources of NH4 and SRP include diffusion of nutrients from decomposed peat, decomposing aquatic vegetation, or upwelling ground water. In addition to these inputs, evapoconcentration raised surface-water solute concentrations to exceedingly high values by the end of summer. The increase was most pronounced in the South Unit, where specific conductance reached 2,500 uS/cm and median concentrations of total nitrogen and total phosphorus reached 18,000-36,500 ug-N/L and about 18,000-26,000 ug-P/L, respectively. Water-column SRP and total phosphorus levels decreased during autumn and winter following inputs of irrigation water and precipitation, which have lower nutrient concentrations. The SRP concentrations, however, decreased faster than the dilution rate alone, possibly due to precipitation of phosphorus with iron, manganese, or calcium. The high concentrations of dissolved nitrogen and phosphorus during the growing season give rise to a rich plant community in the wetland consisting of emergent and submergent macrophytes and algae including phytoplankton and benthic and epiphytic algae that have pronounced effects on dissolved oxygen (DO) and pH. Midday readings of surface-water DO during summer often were supersaturated (as much as 310 percent saturation) with elevated pH (as much as 9.2 units), indicative of high rates of photosynthesis. Minimum DO concentrations in the shallow ground-water piezometer wells were 0.4 mg/L in the North Unit and 0.8 mg/L in the South Unit during summer, which is probably low enough to support microbial denitrification. Denitrification was confirmed during in-situ experiments conducted at the sediment-water interface, but rates were low due to low background nitrate (NO3). Nevertheless, denitrification (and plant uptake) likely contribute to low nitrate levels. Another possible cause of low nitrate levels is dissimilatory nitrate reduction to ammonia (DNRA), a microbial process that converts and decreases nitrate to ammonia. DNRA explains the excess ammonia production measured in the chambers treated with nitrate. Surface-water levels and standing surface-water volume in the Wood River Wetland reached a maximum in early spring, inundating 80-90 percent of the wetland. Surface-water levels and standing volume then declined reaching a minimum in August through November, when the South Unit was only 10 percent inundated and the North Unit was nearly dry. The shallow ground-water levels followed a trend similar to surface-water levels and indicated a strong upward gradient. A monthly water budget was developed individually for the North

A model for the estimation of the surface fluxes of momentum, heat and moisture of the cloud topped marine atmospheric boundary layer from satellite measurable parameters. M.S. Thesis

NASA Technical Reports Server (NTRS)

Allison, D. E.

1984-01-01

A model is developed for the estimation of the surface fluxes of momentum, heat, and moisture of the cloud topped marine atmospheric boundary layer by use of satellite remotely sensed parameters. The parameters chosen for the problem are the integrated liquid water content, q sub li, the integrated water vapor content, q sub vi, the cloud top temperature, and either a measure of the 10 meter neutral wind speed or the friction velocity at the surface. Under the assumption of a horizontally homogeneous, well-mixed boundary layer, the model calculates the equivalent potential temperature and total water profiles of the boundary layer along with the boundary layer height from inputs of q sub li, q sub vi, and cloud top temperature. These values, along with the 10m neutral wind speed or friction velocity and the sea surface temperature are then used to estimate the surface fluxes. The development of a scheme to parameterize the integrated water vapor outside of the boundary layer for the cases of cold air outbreak and California coastal stratus is presented.

Streamwater nitrate concentrations in six agricultural catchments in Scotland.

PubMed

Hooda, P S; Moynagh, M; Svoboda, I F; Thurlow, M; Stewart, M; Thomson, M; Anderson, H A

1997-08-01

The concentrations of nitrate-N (NO3-N) in catchment inputs and outputs have been compared and contrasted between 6 farm catchments in Scotland, 3 in the West and 3 in the North-East. Forms of intensive animal farming ranging between beef and dairy cattle, sheep and poultry give different sources for potential NO3-N leakage from the systems. While stream reaches bordered by intensive cereal production give rise to the largest inputs to surface waters, climatic influences result in the more-efficient use of fertilizer- and farm waste-N in the West, and an enhanced potential for N-loss to waters in the cooler North-East, regardless of the N-inputs being considerably lower in the latter region. Although the EC Nitrate Directive limit of 11.3 mg NO3-N 1(-1) was not exceeded, peak values occurring during summer baseflows and autumn soil rewetting were commonly larger than the 'target' maximum concentration of 5.65 mg NO3-N 1-1.

On the radiocarbon record in banded corals: exchange parameters and net transport of /sup 14/CO/sub 2/ between atmosphere and surface ocean

DOE Office of Scientific and Technical Information (OSTI.GOV)

Druffel, E.M.; Suess, H.E.

1983-02-20

We have made radiocarbon measurements of banded hermatypic corals from Florida, Belize, and the Galapagos Islands. Interpretation is presented here of these previously reported results. These measurements represent the /sup 14/C//sup 12/C ratios in dissolved inorganic carbon (DIOC) in the surface ocean waters of the Gulf Stream and the Peru Current at the time of coral ring formation. A depletion in radiocarbon concentration was observed incoral rings that grew from A.D. 1900--1952. It was caused by dilution of existing /sup 14/C levels with dead CO/sub 2/ from fossil fuel burning (the Suess effect, or S/sub e/). A similar trend wasmore » observed in the distribution of bomb-produced /sup 14/C in corals that had grown during the years following A.D. 1952. The concentration of bomb-produced radiocarbon was much higher in corals from temperate regions (Florida, Belize, Hawaiian Islands) than in corals from tropical regions (Galapagos Islands and Canton Island). The apparent radiocarbon ages of the surface waters in temperate and tropical oceans during the preanthropogenic period range from about 280 to 520 years B.P. (-40 to -69%). At all investigated locations, it is likely that waters at subsurface depths have the same apparent radiocarbon age of about 670 years B.P. From the change of oceanic ..delta../sup 14/C in the surface during post-bomb times, the approximate annual rate of net input of /sup 14/CO/sub 2/ to the ocean waters is calculated to be about 8% of the prevailing /sup 14/C difference between atmosphere and ocean. From this input and from preanthropogenic ..delta../sup 14/C values found at each location, it can be seen that vertical mixing of water in the Peru Current is about 3 times greater than that in the Gulf Stream.« less

Atmospheric aerosol deposition influences marine microbial communities in oligotrophic surface waters of the western Pacific Ocean

NASA Astrophysics Data System (ADS)

Maki, Teruya; Ishikawa, Akira; Mastunaga, Tomoki; Pointing, Stephen B.; Saito, Yuuki; Kasai, Tomoaki; Watanabe, Koichi; Aoki, Kazuma; Horiuchi, Amane; Lee, Kevin C.; Hasegawa, Hiroshi; Iwasaka, Yasunobu

2016-12-01

Atmospheric aerosols contain particulates that are deposited to oceanic surface waters. These can represent a major source of nutrients, trace metals, and organic compounds for the marine environment. The Japan Sea and the western Pacific Ocean are particularly affected by aerosols due to the transport of desert dust and industrially derived particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) from continental Asia. We hypothesized that supplementing seawater with aerosol particulates would lead to measurable changes in surface water nutrient composition as well as shifts in the marine microbial community. Shipboard experiments in the Pacific Ocean involved the recovery of oligotrophic oceanic surface water and subsequent supplementation with aerosol particulates obtained from the nearby coastal mountains, to simulate marine particulate input in this region. Initial increases in nitrates due to the addition of aerosol particulates were followed by a decrease correlated with the increase in phytoplankton biomass, which was composed largely of Bacillariophyta (diatoms), including Pseudo-nitzschia and Chaetoceros species. This shift was accompanied by changes in the bacterial community, with apparent increases in the relative abundance of heterotrophic Rhodobacteraceae and Colwelliaceae in aerosol particulate treated seawater. Our findings provide empirical evidence revealing the impact of aerosol particulates on oceanic surface water microbiology by alleviating nitrogen limitation in the organisms.

A global, 30-m resolution land-surface water body dataset for 2000

NASA Astrophysics Data System (ADS)

Feng, M.; Sexton, J. O.; Huang, C.; Song, D. X.; Song, X. P.; Channan, S.; Townshend, J. R.

2014-12-01

Inland surface water is essential to terrestrial ecosystems and human civilization. The distribution of surface water in space and its change over time are related to many agricultural, environmental and ecological issues, and are important factors that must be considered in human socioeconomic development. Accurate mapping of surface water is essential for both scientific research and policy-driven applications. Satellite-based remote sensing provides snapshots of Earth's surface and can be used as the main input for water mapping, especially in large areas. Global water areas have been mapped with coarse resolution remotely sensed data (e.g., the Moderate Resolution Imaging Spectroradiometer (MODIS)). However, most inland rivers and water bodies, as well as their changes, are too small to map at such coarse resolutions. Landsat TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) imagery has a 30m spatial resolution and provides decades of records (~40 years). Since 2008, the opening of the Landsat archive, coupled with relatively lower costs associated with computing and data storage, has made comprehensive study of the dynamic changes of surface water over large even global areas more feasible. Although Landsat images have been used for regional and even global water mapping, the method can hardly be automated due to the difficulties on distinguishing inland surface water with variant degrees of impurities and mixing of soil background with only Landsat data. The spectral similarities to other land cover types, e.g., shadow and glacier remnants, also cause misidentification. We have developed a probabilistic based automatic approach for mapping inland surface water bodies. Landsat surface reflectance in multiple bands, derived water indices, and data from other sources are integrated to maximize the ability of identifying water without human interference. The approach has been implemented with open-source libraries to facilitate processing large amounts of Landsat images on high-performance computing machines. It has been applied to the ~9,000 Landsat scenes of the Global Land Survey (GLS) 2000 data collection to produce a global, 30m resolution inland surface water body data set, which will be made available on the Global Land Cover Facility (GLCF) website (http://www.landcover.org).

Potential contribution of surface-dwelling Sargassum algae to deep-sea ecosystems in the southern North Atlantic

NASA Astrophysics Data System (ADS)

Baker, Philip; Minzlaff, Ulrike; Schoenle, Alexandra; Schwabe, Enrico; Hohlfeld, Manon; Jeuck, Alexandra; Brenke, Nils; Prausse, Dennis; Rothenbeck, Marcel; Brix, Saskia; Frutos, Inmaculada; Jörger, Katharina M.; Neusser, Timea P.; Koppelmann, Rolf; Devey, Colin; Brandt, Angelika; Arndt, Hartmut

2018-02-01

Deep-sea ecosystems, limited by their inability to use primary production as a source of carbon, rely on other sources to maintain life. Sedimentation of organic carbon into the deep sea has been previously studied, however, the high biomass of sedimented Sargassum algae discovered during the VEMA Transit expedition in 2014/2015 to the southern North Atlantic, and its potential as a regular carbon input, has been an underestimated phenomenon. To determine the potential for this carbon flux, a literature survey of previous studies that estimated the abundance of surface water Sargassum was conducted. We compared these estimates with quantitative analyses of sedimented Sargassum appearing on photos taken with an autonomous underwater vehicle (AUV) directly above the abyssal sediment during the expedition. Organismal communities associated to Sargassum fluitans from surface waters were investigated and Sargassum samples collected from surface waters and the deep sea were biochemically analyzed (fatty acids, stable isotopes, C:N ratios) to determine degradation potential and the trophic significance within deep-sea communities. The estimated Sargassum biomass (fresh weight) in the deep sea (0.07-3.75 g/m2) was several times higher than that estimated from surface waters in the North Atlantic (0.024-0.84 g/m2). Biochemical analysis showed degradation of Sargassum occurring during sedimentation or in the deep sea, however, fatty acid and stable isotope analysis did not indicate direct trophic interactions between the algae and benthic organisms. Thus, it is assumed that components of the deep-sea microbial food web form an important link between the macroalgae and larger benthic organisms. Evaluation of the epifauna showed a diverse nano- micro-, meio, and macrofauna on surface Sargassum and maybe transported across the Atlantic, but we had no evidence for a vertical exchange of fauna components. The large-scale sedimentation of Sargassum forms an important trophic link between surface and benthic production and has to be further considered in the future as a regular carbon input to the deep-sea floor in the North Atlantic.

Mercury in sediment, water, and fish in a managed tropical wetland-lake ecosystem.

PubMed

Malczyk, Evan A; Branfireun, Brian A

2015-08-15

Mercury pollution has not been well documented in the inland lakes or fishes of Mexico, despite the importance of freshwater fish as a source of protein in local diets. Total mercury and methylmercury in waters, sediments, and the commercial fish catch were investigated in Lake Zapotlán, Mexico. Concentrations of total and methylmercury were very high in runoff and wastewater inputs, but very low in sediments and surface waters of the open water area of the lake. Concentrations of total mercury in tilapia and carp were very low, consistent with the low concentrations in lake water and sediments. Particle settling, sorption, the biogeochemical environment, and/or bloom dilution are all plausible explanations for the significant reductions in both total mercury and methylmercury. Despite very high loading of mercury, this shallow tropical lake was not a mercury-impaired ecosystem, and these findings may translate across other shallow, alkaline tropical lakes. Importantly, the ecosystem services that seemed to be provided by peripheral wetlands in reducing mercury inputs highlight the potential for wetland conservation or restoration in Mexico. Copyright © 2015. Published by Elsevier B.V.

Filamentary superhydrophobic Teflon surfaces: Moderate apparent contact angle but superior air-retaining properties.

PubMed

Di Mundo, Rosa; Bottiglione, Francesco; Palumbo, Fabio; Notarnicola, Michele; Carbone, Giuseppe

2016-11-15

Micro-scale textured Teflon surfaces, resulting from plasma etching modification, show extremely high water contact angle values and fairly good resistance to water penetration when hit by water drops at medium-high speed. This behavior is more pronounced when these surfaces present denser and smaller micrometric reliefs. Tailoring the top of these reliefs with a structure which further stabilizes the air may further increase resistance to wetting (water penetration) under static and dynamic conditions. Conditions of the oxygen fed plasma were tuned in order to explore the possibility of obtaining differently topped structures on the surface of the polymer. Scanning Electron Microscopy (SEM) was used to explore topography and X-ray Photoelectron Spectroscopy (XPS) to assess chemical similarity of the modified surfaces. Beside the usual advancing and receding water contact angle (WCA) measurements, surfaces were subjected to high speed impacting drops and immersion in water. At milder, i.e. shorter time and lower input power, plasma conditions formation of peculiar filaments is observed on the top of the sculpted reliefs. Filamentary topped surfaces result in a lower WCA than the spherical ones, appearing in this sense less superhydrophobic. However, these surfaces give rise to the formation of a more pronounced air layer when placed underwater. Further, when hit by water drops falling at medium/high speed, they show a higher resistance to water penetration and a sensitively lower surface-liquid contact time. The contact time is as low as previously observed only on heated solids. This behavior may be ascribed to the cavities formed beneath the filaments which, similarly with the salvinia leaf structures, require a surplus of pressure to be filled by water. Also, it suggests a different concept of superhydrophobicity, which cannot be expected on the basis of the conventional water contact angle characterization. Copyright © 2016 Elsevier Inc. All rights reserved.

MSWT-01, flood disaster water treatment solution from common ideas

NASA Astrophysics Data System (ADS)

Ananto, Gamawan; Setiawan, Albertus B.; Z, Darman M.

2013-06-01

Indonesia has a lot of potential flood disaster places with clean water problems faced. Various solution programs always initiated by Government, companies CSR, and people sporadical actions to provide clean water; with their advantages and disadvantages respectively. One solution is easy to operate for instance, but didn't provide adequate capacity, whereas the other had ideal performance but more costly. This situation inspired to develop a water treatment machine that could be an alternative favor. There are many methods could be choosed; whether in simple, middle or high technology, depends on water source input and output result quality. MSWT, Mobile Surface Water Treatment, is an idea for raw water in flood area, basically made for 1m3 per hour. This water treatment design adopted from combined existing technologies and related literatures. Using common ideas, the highlight is how to make such modular process put in compact design elegantly, and would be equipped with mobile feature due to make easier in operational. Through prototype level experiment trials, the machine is capable for producing clean water that suitable for sanitation and cooking/drinking purposes although using contaminated water input source. From the investment point of view, such machine could be also treated as an asset that will be used from time to time when needed, instead of made for project approach only.

Comparison of Three Operative Models for Estimating the Surface Water Deficit using ASTER Reflective and Thermal Data

PubMed Central

García, Mónica; Villagarcía, Luis; Contreras, Sergio; Domingo, Francisco; Puigdefábregas, Juan

2007-01-01

Three operative models with minimum input data requirements for estimating the partition of available surface energy into sensible and latent heat flux using ASTER data have been evaluated in a semiarid area in SE Spain. The non-evaporative fraction (NEF) is proposed as an indicator of the surface water deficit. The best results were achieved with NEF estimated using the “Simplified relationship” for unstable conditions (NEFSeguin) and with the S-SEBI (Simplified Surface Energy Balance Index) model corrected for atmospheric conditions (NEFS-SEBIt,) which both produced equivalent results. However, results with a third model, NEFCarlson, that estimates the exchange coefficient for sensible heat transfer from NDVI, were unrealistic for sites with scarce vegetation cover. These results are very promising for an operative monitoring of the surface water deficit, as validation with field data shows reasonable errors, within those reported in the literature (RMSE were 0.18 and 0.11 for the NEF, and 29.12 Wm-2 and 25.97 Wm-2 for sensible heat flux, with the Seguin and S-SEBIt models, respectively).

Inevitable end-of-21st-century trends toward earlier surface runoff timing in California's Sierra Nevada Mountains

NASA Astrophysics Data System (ADS)

Schwartz, M. A.; Hall, A. D.; Sun, F.; Walton, D.; Berg, N.

2015-12-01

Hybrid dynamical-statistical downscaling is used to produce surface runoff timing projections for California's Sierra Nevada, a high-elevation mountain range with significant seasonal snow cover. First, future climate change projections (RCP8.5 forcing scenario, 2081-2100 period) from five CMIP5 global climate models (GCMs) are dynamically downscaled. These projections reveal that future warming leads to a shift toward earlier snowmelt and surface runoff timing throughout the Sierra Nevada region. Relationships between warming and surface runoff timing from the dynamical simulations are used to build a simple statistical model that mimics the dynamical model's projected surface runoff timing changes given GCM input or other statistically-downscaled input. This statistical model can be used to produce surface runoff timing projections for other GCMs, periods, and forcing scenarios to quantify ensemble-mean changes, uncertainty due to intermodel variability and consequences stemming from choice of forcing scenario. For all CMIP5 GCMs and forcing scenarios, significant trends toward earlier surface runoff timing occur at elevations below 2500m. Thus, we conclude that trends toward earlier surface runoff timing by the end-of-the-21st century are inevitable. The changes to surface runoff timing diagnosed in this study have implications for many dimensions of climate change, including impacts on surface hydrology, water resources, and ecosystems.

CIRMIS Data system. Volume 2. Program listings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.

1980-01-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologicmore » systems, model the transport of released radionuclides through the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. The various input parameters required in the analysis are compiled in data systems. The data are organized and prepared by various input subroutines for utilization by the hydraulic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required.The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System is a storage and retrieval system for model input and output data, including graphical interpretation and display. This is the second of four volumes of the description of the CIRMIS Data System.« less

Assessment of effectiveness of geologic isolation systems. CIRMIS data system. Volume 4. Driller's logs, stratigraphic cross section and utility routines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.

1980-01-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (ONWI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologicmore » systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. The various input parameters required in the analysis are compiled in data systems. The data are organized and prepared by various input subroutines for use by the hydrologic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required. The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System is a storage and retrieval system for model input and output data, including graphical interpretation and display. This is the fourth of four volumes of the description of the CIRMIS Data System.« less

Water shortage risk assessment considering large-scale regional transfers: a copula-based uncertainty case study in Lunan, China.

PubMed

Gao, Xueping; Liu, Yinzhu; Sun, Bowen

2018-06-05

The risk of water shortage caused by uncertainties, such as frequent drought, varied precipitation, multiple water resources, and different water demands, brings new challenges to the water transfer projects. Uncertainties exist for transferring water and local surface water; therefore, the relationship between them should be thoroughly studied to prevent water shortage. For more effective water management, an uncertainty-based water shortage risk assessment model (UWSRAM) is developed to study the combined effect of multiple water resources and analyze the shortage degree under uncertainty. The UWSRAM combines copula-based Monte Carlo stochastic simulation and the chance-constrained programming-stochastic multiobjective optimization model, using the Lunan water-receiving area in China as an example. Statistical copula functions are employed to estimate the joint probability of available transferring water and local surface water and sampling from the multivariate probability distribution, which are used as inputs for the optimization model. The approach reveals the distribution of water shortage and is able to emphasize the importance of improving and updating transferring water and local surface water management, and examine their combined influence on water shortage risk assessment. The possible available water and shortages can be calculated applying the UWSRAM, also with the corresponding allocation measures under different water availability levels and violating probabilities. The UWSRAM is valuable for mastering the overall multi-water resource and water shortage degree, adapting to the uncertainty surrounding water resources, establishing effective water resource planning policies for managers and achieving sustainable development.

Impact of mine wastewaters on greenhouse gas emissions from northern peatlands used for mine water treatment

NASA Astrophysics Data System (ADS)

Palmer, Katharina; Ronkanen, Anna-Kaisa; Klöve, Björn; Hynynen, Jenna; Maljanen, Marja

2015-04-01

The amount of wastewaters generated during mining operations is increasing along with the increasing number of operation mines, which poses great challenges for mine water management and purification. Mine wastewaters contain high concentrations of nitrogen compounds such as nitrate (NO3-) and ammonium (NH4+) originating from remnant explosives as well as sulfate (SO42-) originating from the oxidation of sulfidic ores. At a mine site in Finnish Lapland, two natural peatlands have been used for cost-effective passive wastewater treatment. One peatland have been used for the treatment of drainage waters (TP 1), while the other has been used for the treatment of process-based wastewaters (TP 4). In this study, the impact of mine water derived nitrogen compounds as well as SO42- on the emission of the potent greenhouse gases methane (CH4) and nitrous oxide (N2O) from those treatment peatlands was investigated. Contaminant concentrations in the input and output waters of the treatment peatlands were monitored which allowed for the calculation of contaminant-specific retention efficiencies. Treatment peatlands showed generally good retention efficiencies for metals and metalloids (e.g. nickel, arsenic, antimony, up to 98% reduction in concentration) with rather low input-concentrations (i.e., in the μg/l-range). On the other hand, retention of contaminants with high input-concentrations (i.e., in mg/l-range) such as NO3-, NH4+ and SO42- was much lower (4-41%, 30-60% and -42-30%, respectively), indicating the limited capability of the treatment peatlands to cope with such high input concentrations. NO3- and NH4+ concentrations were determined in surface and pore water from TP 4 in July 2013 as well as in surface water from TP 1 and TP 4 in October 2013. Up to 720 μM NO3- and up to 600 μM NH4+ were detected in surface water of TP 4 in July 2013. NO3- and NH4+ concentrations in surface waters were highest near the mine wastewater distribution ditch and decreased with increasing distances from the ditch. NO3- concentrations were lower in pore water than in surface water, and the peak in NO3- concentration shifted further away from the distribution ditch with increasing depth. On the contrary, NH4+ concentrations were generally higher in pore water than in surface water, and peak concentrations increased with increasing depth. Highest NH4+ concentrations were detected in 30 to 60 cm depth near the outlet at the south end of TP 4. Fluxes of the greenhouse gases CH4 and N2O from 4 sampling points (2 from TP 4, 1 from TP 1, 1 from reference area) were measured on 7 different occasions 2013 and 2014. CH4 emissions were in the same range as measured in other northern pristine peatlands in the reference area, which is not influenced by mine wastewaters. Treatment peatlands showed only very minor CH4 emissions or even CH4 uptake. On the other hand, treatment peatlands showed high N2O emissions, which were in the same range as N2O emissions observed from northern peat soils used for agriculture. Highest emissions were generally observed near the wastewater distribution ditch of TP 4. N2O emissions from the reference area were negligible or even negative. NO3-, NH4+ and SO42- concentrations were determined from surface waters from each sampling point and sampling occasion. N2O emissions were positively correlated with NO3- concentrations, indicating denitrification-derived N2O production in treatment peatlands. On the other hand, CH4 emissions were negatively correlated with SO42- and NO3- concentrations, indicating that the presence of alternative electron acceptors in large amounts suppresses CH4 production in treatment peatlands. In conclusion, the study revealed that (i) treatment peatlands receive high loads of NO3-, NH4+ and SO42- which are not well retained in the peatlands, (ii) mine wastewaters positively and negatively affect N2O and CH4 emissions, respectively, (iii) N2O emissions are positively correlated with NO3- concentrations, and (iv) CH4 emissions are negatively correlated with NO3- and SO42- concentrations. This study thus illustrates the pronounced impacts of mine wastewaters on processes involved in greenhouse gas turnover in peatlands ecosystems.

Use of simulated evaporation to assess the potential for scale formation during reverse osmosis desalination

USGS Publications Warehouse

Huff, G.F.

2004-01-01

The tendency of solutes in input water to precipitate efficiency lowering scale deposits on the membranes of reverse osmosis (RO) desalination systems is an important factor in determining the suitability of input water for desalination. Simulated input water evaporation can be used as a technique to quantitatively assess the potential for scale formation in RO desalination systems. The technique was demonstrated by simulating the increase in solute concentrations required to form calcite, gypsum, and amorphous silica scales at 25??C and 40??C from 23 desalination input waters taken from the literature. Simulation results could be used to quantitatively assess the potential of a given input water to form scale or to compare the potential of a number of input waters to form scale during RO desalination. Simulated evaporation of input waters cannot accurately predict the conditions under which scale will form owing to the effects of potentially stable supersaturated solutions, solution velocity, and residence time inside RO systems. However, the simulated scale-forming potential of proposed input waters could be compared with the simulated scale-forming potentials and actual scale-forming properties of input waters having documented operational histories in RO systems. This may provide a technique to estimate the actual performance and suitability of proposed input waters during RO.

Groundwater geochemistry of Isla de Mona, Puerto Rico

USGS Publications Warehouse

Wicks, C.M.; Troester, J.W.

1998-01-01

In this study, we explore the differences between the hydrogeochemical processes observed in a setting that is open to input from the land surface and in a setting that is closed with respect to input from the land surface. The closed setting was a water-filled passage in a cave. Samples of groundwater and of a solid that appeared to be suspended in the relatively fresh region of saline-freshwater mixing zone were collected. The solid was determined to be aragonite. Based on the analyses of the composition and saturation state of the groundwater, the mixing of fresh and saline water and precipitation of aragonite are the controlling geochemical processes in this mixing zone. We found no evidence of sulfate reduction. Thus, this mixing zone is similar to that observed in Caleta Xel Ha, Quintana Roo, also a system that is closed with respect to input from the land surface. The open setting was an unconfined aquifer underlying the coastal plain along which four hand-dug wells are located. Two wells are at the downgradient ends of inferred flowpaths and one is along a flowpath. The composition of the groundwater in the downgradient wells is sulfide-rich and brackish. In contrast, at the well located along a flow line, the groundwater is oxygenated and brackish. All groundwater is oversaturated with respect to calcite, aragonite, and dolomite. The composition is attributed to mixing of fresh and saline groundwater, CO2 outgassing, and sulfate reduction. This mixing zone is geochemically similar to that observed in blue holes and cenotes.

Moss stable isotopes (carbon-13, oxygen-18) and testate amoebae reflect environmental inputs and microclimate along a latitudinal gradient on the Antarctic Peninsula.

PubMed

Royles, Jessica; Amesbury, Matthew J; Roland, Thomas P; Jones, Glyn D; Convey, Peter; Griffiths, Howard; Hodgson, Dominic A; Charman, Dan J

2016-07-01

The stable isotope compositions of moss tissue water (δ(2)H and δ(18)O) and cellulose (δ(13)C and δ(18)O), and testate amoebae populations were sampled from 61 contemporary surface samples along a 600-km latitudinal gradient of the Antarctic Peninsula (AP) to provide a spatial record of environmental change. The isotopic composition of moss tissue water represented an annually integrated precipitation signal with the expected isotopic depletion with increasing latitude. There was a weak, but significant, relationship between cellulose δ(18)O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ(13)C values were dependent on moss species and water content, and may reflect site exposure to strong winds. Testate amoebae assemblages were characterised by low concentrations and taxonomic diversity, with Corythion dubium and Microcorycia radiata types the most cosmopolitan taxa. The similarity between the intra- and inter-site ranges measured in all proxies suggests that microclimate and micro-topographical conditions around the moss surface were important determinants of proxy values. Isotope and testate amoebae analyses have proven value as palaeoclimatic, temporal proxies of climate change, whereas this study demonstrates that variations in isotopic and amoeboid proxies between microsites can be beyond the bounds of the current spatial variability in AP climate.

Turnover and release of P-, N-, Si-nutrients in the Mexicali Valley (Mexico): interactions between the lower Colorado River and adjacent ground- and surface water systems.

PubMed

Orozco-Durán, A; Daesslé, L W; Camacho-Ibar, V F; Ortiz-Campos, E; Barth, J A C

2015-04-15

A study on dissolved nitrate, ammonium, phosphate and silicate concentrations was carried out in various water compartments (rivers, drains, channels, springs, wetland, groundwater, tidal floodplains and ocean water) in the Mexicali Valley and the Colorado River delta between 2012 and 2013, to assess modern potential nutrient sources into the marine system after river damming. While nitrate and silicate appear to have a significant input into the coastal ocean, phosphate is rapidly transformed into a particulate phase. Nitrate is, in general, rapidly bio-consumed in the surface waters rich in micro algae, but its excess (up to 2.02 mg L(-1) of N from NO3 in winter) in the Santa Clara Wetland represents a potential average annual source to the coast of 59.4×10(3)kg N-NO3. Despite such localized inputs, continuous regional groundwater flow does not appear to be a source of nitrate to the estuary and coastal ocean. Silicate is associated with groundwaters that are also geothermally influenced. A silicate receiving agricultural drain adjacent to the tidal floodplain had maximum silicate concentrations of 16.1 mg L(-1) Si-SiO2. Seepage of drain water and/or mixing with seawater during high spring tides represents a potential source of dissolved silicate and nitrate into the Gulf of California. Copyright © 2015 Elsevier B.V. All rights reserved.

High Resolution Observations of Dissolved Iron Distribution Along a Coastal Offshore Transect in the Eastern North Atlantic.

NASA Astrophysics Data System (ADS)

Blain, S.; Laes, A.; Laan, P.; Achterberg, E.; de Baar, H.

2002-12-01

In order to better understand and quantify the inputs of iron from below in the water column a detailed section from the coast to offshore has been studied in the eastern North Atlantic. The section, extended from 47°36 58 N, 4°14 51 W (depth 96 m) to 46°00 00 N, 8°00 00 W (depth 4912 m). The cruise took place in March 2002, on board R/V Pelagia, as part of the European Union project IRONAGES. Fifteen stations have been sampled for dissolved iron (DFe) and nutrients analysis. Go Flo bottles mounted on a kevlar cable were used for clean seawater sampling in the water column. A torpedo fish and trace metal clean bellows pump were used for surface sampling. Sample were filtered on-line through an 0.2 μm cartridge. The DFe concentrations were measured onboard using a FIA method with on line preconcentration (8-HQ resin) and chemiluminescence detection (mean blank = 28 pM, mean limit of detection= 39 pM). The coastal stations over the shelf showed the highest concentrations of DFe. In this part of the transect, the concentration decreased from the surface to the bottom. Maxima (1-2.4 nM) were associated with increase in turbidity demonstrating the DFe inputs associated with re-suspended sediments and/or pore waters. In the eastern part of the transect, water of the Loire river has been identified has a source of iron. Close to the shelf break the two dimensional iron distribution became more complex. A tidal front, internal waves and slope currents created a patchy distribution of DFe. Evertheless the input from below was always observable at depth between 500 and 1200 m. Finally, in the western part of the transect, off the plateau, the concentration of DFe was strongly correlated with the occurrence of different water masses (see abstract by A. Laës).

Modeling transport phenomena and uncertainty quantification in solidification processes

NASA Astrophysics Data System (ADS)

Fezi, Kyle S.

Direct chill (DC) casting is the primary processing route for wrought aluminum alloys. This semicontinuous process consists of primary cooling as the metal is pulled through a water cooled mold followed by secondary cooling with a water jet spray and free falling water. To gain insight into this complex solidification process, a fully transient model of DC casting was developed to predict the transport phenomena of aluminum alloys for various conditions. This model is capable of solving mixture mass, momentum, energy, and species conservation equations during multicomponent solidification. Various DC casting process parameters were examined for their effect on transport phenomena predictions in an alloy of commercial interest (aluminum alloy 7050). The practice of placing a wiper to divert cooling water from the ingot surface was studied and the results showed that placement closer to the mold causes remelting at the surface and increases susceptibility to bleed outs. Numerical models of metal alloy solidification, like the one previously mentioned, are used to gain insight into physical phenomena that cannot be observed experimentally. However, uncertainty in model inputs cause uncertainty in results and those insights. The analysis of model assumptions and probable input variability on the level of uncertainty in model predictions has not been calculated in solidification modeling as yet. As a step towards understanding the effect of uncertain inputs on solidification modeling, uncertainty quantification (UQ) and sensitivity analysis were first performed on a transient solidification model of a simple binary alloy (Al-4.5wt.%Cu) in a rectangular cavity with both columnar and equiaxed solid growth models. This analysis was followed by quantifying the uncertainty in predictions from the recently developed transient DC casting model. The PRISM Uncertainty Quantification (PUQ) framework quantified the uncertainty and sensitivity in macrosegregation, solidification time, and sump profile predictions. Uncertain model inputs of interest included the secondary dendrite arm spacing, equiaxed particle size, equiaxed packing fraction, heat transfer coefficient, and material properties. The most influential input parameters for predicting the macrosegregation level were the dendrite arm spacing, which also strongly depended on the choice of mushy zone permeability model, and the equiaxed packing fraction. Additionally, the degree of uncertainty required to produce accurate predictions depended on the output of interest from the model.

Modeling the Effects of Irrigation on Land Surface Fluxes and States over the Conterminous United States: Sensitivity to Input Data and Model Parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leng, Guoyong; Huang, Maoyi; Tang, Qiuhong

2013-09-16

Previous studies on irrigation impacts on land surface fluxes/states were mainly conducted as sensitivity experiments, with limited analysis of uncertainties from the input data and model irrigation schemes used. In this study, we calibrated and evaluated the performance of irrigation water use simulated by the Community Land Model version 4 (CLM4) against observations from agriculture census. We investigated the impacts of irrigation on land surface fluxes and states over the conterminous United States (CONUS) and explored possible directions of improvement. Specifically, we found large uncertainty in the irrigation area data from two widely used sources and CLM4 tended to producemore » unrealistically large temporal variations of irrigation demand for applications at the water resources region scale over CONUS. At seasonal to interannual time scales, the effects of irrigation on surface energy partitioning appeared to be large and persistent, and more pronounced in dry than wet years. Even with model calibration to yield overall good agreement with the irrigation amounts from the National Agricultural Statistics Service (NASS), differences between the two irrigation area datasets still dominate the differences in the interannual variability of land surface response to irrigation. Our results suggest that irrigation amount simulated by CLM4 can be improved by (1) calibrating model parameter values to account for regional differences in irrigation demand and (2) accurate representation of the spatial distribution and intensity of irrigated areas.« less

Nitrate dynamics within the Pajaro River, a nutrient-rich, losing stream

USGS Publications Warehouse

Ruehl, C.R.; Fisher, A.T.; Los, Huertos M.; Wankel, Scott D.; Wheat, C.G.; Kendall, C.; Hatch, C.E.; Shennan, C.

2007-01-01

The major ion chemistry of water from an 11.42-km reach of the Pajaro River, a losing stream in central coastal California, shows a consistent pattern of higher concentrations during the 2nd (dry) half of the water year. Most solutes are conserved during flow along the reach, but [NO 3-] decreases by ???30% and is accompanied by net loss of channel discharge and extensive surface-subsurface exchange. The corresponding net NO3- uptake length is 37 ?? 13 km (42 ?? 12 km when normalized to the conservative solute Cl-), and the areal NO3- uptake rate is 0.5 ??mol m -2 s-1. The observed reduction in [NO3-] along the reach results from one or more internal sinks, not dilution by ground water, hill-slope water, or other water inputs. Observed reductions in [NO3-] and channel discharge along the experimental reach result in a net loss of 200-400 kg/d of NO3--N, ???50% of the input load. High-resolution (temporal and spatial) sampling indicates that most of the NO3- loss occurs along the lower part of the reach, where there is the greatest seepage loss and surface-subsurface exchange of water. Stable isotopes of NO 3-, total dissolved P concentrations, and streambed chemical profiles suggest that denitrification is the most significant NO 3- sink along the reach. Denitrification efficiency, as expressed through downstream enrichment in 15N-NO3-, varies considerably during the water year. When discharge is greater (typically earlier in the water year), denitrification is least efficient and downstream enrichment in 15N-NO3- is greatest. When discharge is lower, denitrification in the streambed appears to occur with greater efficiency, resulting in lower downstream enrichment in 15N-NO3-. ?? 2007 by The North American Benthological Society.

Anthropogenic organochlorine compounds as potential tracers for regional water masses: A case study of estuarine plume, coastal eddy, wind-driven upwelling and long-range warm current.

PubMed

Ya, Miaolei; Wu, Yuling; Li, Yongyu; Wang, Xinhong

2017-03-01

Water masses are the crucial factor driving the terrigenous anthropogenic organochlorine compounds (OCs) migration from the coast to open sea. Therefore, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the Northern South China Sea (NSCS), where different types of water masses are generated by the East Asian summer monsoon: Pearl River estuary plume (PREP), Guangdong offshore eddy (GDEC), South China Sea warm current (SCSWC) and wind-driven upwelling current (WDUC). No discrepant distributions of OC concentrations were found in these water masses (p > 0.05). However, compositions and diagnostic ratios of HCHs, DDTs, trans- or cis-chlordane and PCBs could reflect the discrepancies in the input, transport and transformation of OCs caused by the hydrological characteristics of water masses, therefore, this allowing them to serve as potential tracers of regional water masses. In detail, α/γ-HCH and β-HCH percentages could indicate the weathered residue in the GDEC, long-range transport in the SCSWC, rapid photodegradation in the surface WDUC and biodegradation in the deep WDUC, respectively. The predominance of o, p'-DDT and p, p'-DDT could indicate fresh input in the PREP, GDEC and WDUC. DDT/DDTs of ratios <0.5 also reflected long-range transport in the SCSWC. Different DDD/DDE ratios indicated different oxygen environments of microbial degradation in the surface and deep water of the WDUC. Trans/cis-chlordane ratios could indicate the selective degradation of trans-chlordane in different water masses. Finally, a higher proportion of penta-PCB could reflect the strong paint additive sources carried by river erosion in the PREP. Copyright © 2016 Elsevier Ltd. All rights reserved.

78 FR 58938 - Endangered and Threatened Wildlife and Plants; Determination of Endangered Species Status for the...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-25

..., especially in crop fields and pastures where silt, chemicals, and fertilizers can be directly deposited into... provide consistent water flow, high organic input, and connection to surface streams, which allow for... County cave streams were contaminated by a mixture of organic pollutants that included both current-use...

Evaluation of individual and combined management practices to reduce the off-site transport of pesticides from golf course turf

USDA-ARS?s Scientific Manuscript database

The detection of pesticides, associated with turfgrass management, in storm runoff and surface waters of urban watersheds has raised concerns regarding their source, potential environmental effects and a need for strategies to reduce their inputs. In previous research we discovered that hollow tine ...

Runoff Water Quality During Drought in a Zero-Order Georgia Piedmont Pasture: Nitrogen and Total Organic Carbon

EPA Science Inventory

Approximately 11% of the Southern Piedmont (1.8 million ha) is used for pasture and hay production, mostly under low-input management. Few studies have investigated in the region long-term nitrogen and carbon losses in surface runoff, which can be significant. We present 1999 to ...

The influence of data characteristics on detecting wetland/stream surface-water connections in the Delmarva Peninsula, Maryland and Delaware

USGS Publications Warehouse

Vanderhoof, Melanie; Distler, Hayley; Lang, Megan W.; Alexander, Laurie C.

2018-01-01

The dependence of downstream waters on upstream ecosystems necessitates an improved understanding of watershed-scale hydrological interactions including connections between wetlands and streams. An evaluation of such connections is challenging when, (1) accurate and complete datasets of wetland and stream locations are often not available and (2) natural variability in surface-water extent influences the frequency and duration of wetland/stream connectivity. The Upper Choptank River watershed on the Delmarva Peninsula in eastern Maryland and Delaware is dominated by a high density of small, forested wetlands. In this analysis, wetland/stream surface water connections were quantified using multiple wetland and stream datasets, including headwater streams and depressions mapped from a lidar-derived digital elevation model. Surface-water extent was mapped across the watershed for spring 2015 using Landsat-8, Radarsat-2 and Worldview-3 imagery. The frequency of wetland/stream connections increased as a more complete and accurate stream dataset was used and surface-water extent was included, in particular when the spatial resolution of the imagery was finer (i.e., <10 m). Depending on the datasets used, 12–60% of wetlands by count (21–93% of wetlands by area) experienced surface-water interactions with streams during spring 2015. This translated into a range of 50–94% of the watershed contributing direct surface water runoff to streamflow. This finding suggests that our interpretation of the frequency and duration of wetland/stream connections will be influenced not only by the spatial and temporal characteristics of wetlands, streams and potential flowpaths, but also by the completeness, accuracy and resolution of input datasets.

Nitrogen inputs to a river course in a heavily impacted watershed: a combined hydrochemical and isotopic evaluation (Oglio River Basin, N Italy).

PubMed

Delconte, C A; Sacchi, E; Racchetti, E; Bartoli, M; Mas-Pla, J; Re, V

2014-01-01

This study aims at evaluating sources and processes affecting NO₃(-) concentrations in the Oglio River. Five sampling campaigns considered the main watercourse, tributaries, point pollution sources, springs, and groundwater. Physico-chemical parameters, N forms, B, Sr(2+), stable isotopes (δ(2)HH₂O, δ(18)OH₂O, δ(15)NNO₃, δ(18)ONO₃, δ(11)B) and discharge were measured. Hydrological modelling was performed using mass balance and End Member Mixing Analysis equations. During the irrigation period, in the upstream reach, up to 90% of the natural river flow is diverted for irrigation and industrial purposes; excess water drained from agricultural fields is returned to river in the downstream reach. Results evidenced, in the middle reach, a large input of NO₃(-)-rich groundwater which could be quantified using hydrological modelling. Groundwater inputs are responsible for the sharp, tenfold increase in NO₃(-) in the river water, from 2.2-4.4 up to 33.5 mgL(-1), and are more evident in summer, when discharge is lower. Nevertheless, river water preserves its natural B isotopic composition, indicating that the two tracers do not have a common origin and are not co-migrant. In the lower plain, surface-groundwater interconnections and human disturbances in the water cycle favour the recycling of the compounds in the environment, and lead to a similarity in composition of the different water bodies (Oglio River, tributaries and groundwater). The long lasting agronomical practices have profoundly modified the surface-groundwater equilibrium and chemical characteristics, resulting in a highly buffered system. Infiltrating irrigation water leaches down NO₃(-) which is subsequently denitrified; when returned to the Oglio River, groundwater modifies the river water composition by dilution, in the case of NO₃(-), or by addition, for other constituents (e.g. Cl(-), B). The results of this study indicate that, in order to reduce the NO3(-) transport towards the Adriatic Sea, groundwater contamination should be addressed first, with expected long recovery times. © 2013.

Modeling the impacts of dryland agricultural reclamation on groundwater resources in Northern Egypt using sparse data

NASA Astrophysics Data System (ADS)

Switzman, Harris; Coulibaly, Paulin; Adeel, Zafar

2015-01-01

Demand for freshwater in many dryland environments is exerting negative impacts on the quality and availability of groundwater resources, particularly in areas where demand is high due to irrigation or industrial water requirements to support dryland agricultural reclamation. Often however, information available to diagnose the drivers of groundwater degradation and assess management options through modeling is sparse, particularly in low and middle-income countries. This study presents an approach for generating transient groundwater model inputs to assess the long-term impacts of dryland agricultural land reclamation on groundwater resources in a highly data-sparse context. The approach was applied to the area of Wadi El Natrun in Northern Egypt, where dryland reclamation and the associated water use has been aggressive since the 1960s. Statistical distributions of water use information were constructed from a variety of sparse field and literature estimates and then combined with remote sensing data in spatio-temporal infilling model to produce the groundwater model inputs of well-pumping and surface recharge. An ensemble of groundwater model inputs were generated and used in a 3D groundwater flow (MODFLOW) of Wadi El Natrun's multi-layer aquifer system to analyze trends in water levels and water budgets over time. Validation of results against monitoring records, and model performance statistics demonstrated that despite the extremely sparse data, the approach used in this study was capable of simulating the cumulative impacts of agricultural land reclamation reasonably well. The uncertainty associated with the groundwater model itself was greater than that associated with the ensemble of well-pumping and surface recharge estimates. Water budget analysis of the groundwater model output revealed that groundwater recharge has not changed significantly over time, while pumping has. As a result of these trends, groundwater was estimated to be in a deficit of approximately 24 billion m3 (±15%) in 2011, compared to 1957. A significant trend in water level declines beginning in the 1990s that has been observed in monitoring records was evident in the model results and is directly attributed to abstraction.

Importance of monsoon rainfall in mass fluxes of filtered and unfiltered mercury in Gwangyang Bay, Korea.

PubMed

Jang, Jiyi; Han, Seunghee

2011-03-15

We investigated the effects of the East Asian Summer Monsoon (EASM), which brings approximately half of Korea's annual rainfall in July, on the concentration and particle-water partitioning, and sources of Hg in coastal waters. Surface seawater samples were collected from eight sites in Gwangyang Bay, Korea, during the monsoon (July, 2009) and non-monsoon dry (April and November, 2009) seasons and the concentrations of suspended particulate matter, chlorophyll-a, and unfiltered and filtered Hg were determined. We found significant (p<0.05) increases in filtered Hg in the monsoon season (1.8 ± 0.019 pM) compared to the dry season (0.62 ± 0.047 pM). In contrast, the Hg concentrations associated with particles showed no significant differences (p>0.05) between the monsoon (459 ± 141 pmol g(-1)) and the dry season (346 ± 30 pmol g(-1)), which resulted in decreased particle-water partition coefficients of Hg in the monsoon season compared to the values in the dry season: 5.7 ± 0.1 in April, 5.3 ± 0.1 in July, and 5.8 ± 0.1 in November. The annual Hg input to Gwangyang Bay was estimated at 64 ± 6.6 mol yr(-1) and 27 ± 1.9 mol yr(-1) for unfiltered and filtered Hg, respectively. The Hg discharged from rivers was a major source of Hg in Gwangyang Bay: the river input contributed 83 ± 13% of total input of unfiltered and 73 ± 6.0% of filtered Hg. On a monthly basis, unfiltered Hg input was 17 ± 11 mol month(-1) in the monsoon season and 3.2 ± 0.70 mol month(-1) in the dry season, while filtered Hg input was 7.1 ± 4.1 mol month(-1) in the monsoon and 1.3 ± 0.26 mol month(-1) in the dry. Consequently, the EASM resulted in an unfiltered Hg input 5.3 times greater than the mean dry month input and a filtered Hg input 5.5 times greater than the mean dry month input, which is mainly attributable to enhanced river water discharge during the monsoon season. Copyright © 2011 Elsevier B.V. All rights reserved.

Primary factors affecting water quality and quantity in four watersheds in Eastern Puerto Rico

USGS Publications Warehouse

Murphy, Sheila F.; Stallard, Robert F.

2009-01-01

As part of the U.S. Geological Survey (USGS) Water, Energy, and Biogeochemical Budgets (WEBB) program, four small watersheds in eastern Puerto Rico were monitored to identify and evaluate the effects of geology, landcover, atmospheric deposition, and other factors on stream water quality and quantity. Two catchments are located on coarse-grained granitic plutonic rocks, which weather to quartz- and clay-rich, sandy soils, and two are located on fine-grained volcanic rocks and volcaniclastic sediments, which weather to quartz-poor, fine-grained soils. These differing soil materials result in different hydrologic regimes. Soils on the granitic rocks have greater permeability than those developed on the volcaniclastic rocks, allowing more water infiltration and potentially greater landslide erosion rates. For each bedrock type, one catchment was covered with mature rainforest, and the other catchment was affected by agricultural practices typical of eastern Puerto Rico. These practices led to the erosion of much of the original surface soil in the agricultural watersheds, which introduced large quantities of sediment to stream channels. The agricultural watersheds are undergoing natural reforestation, like much of Puerto Rico. Eastern Puerto Rico receives large atmospheric inputs of marine salts, pollutants from the Northern Hemisphere, and Saharan Desert dust. Marine salts contribute over 80 percent of the ionic charge in precipitation, with peak inputs in January. Intense storms, mostly hurricanes, are associated with exceptionally high chloride concentrations in stream waters. Temperate pollution contributes nitrate, ammonia, and sulfate, with maximum inputs during northern cold fronts in January, April, and May. Pollution inputs have increased through time. Desert dust peaks in June and July, during times of maximum dust transport from the Saharan Desert across the Atlantic Ocean.

Parameterizing a Large-scale Water Balance Model in Regions with Sparse Data: The Tigris-Euphrates River Basins as an Example

NASA Astrophysics Data System (ADS)

Flint, A. L.; Flint, L. E.

2010-12-01

The characterization of hydrologic response to current and future climates is of increasing importance to many countries around the world that rely heavily on changing and uncertain water supplies. Large-scale models that can calculate a spatially distributed water balance and elucidate groundwater recharge and surface water flows for large river basins provide a basis of estimates of changes due to future climate projections. Unfortunately many regions in the world have very sparse data for parameterization or calibration of hydrologic models. For this study, the Tigris and Euphrates River basins were used for the development of a regional water balance model at 180-m spatial scale, using the Basin Characterization Model, to estimate historical changes in groundwater recharge and surface water flows in the countries of Turkey, Syria, Iraq, Iran, and Saudi Arabia. Necessary input parameters include precipitation, air temperature, potential evapotranspiration (PET), soil properties and thickness, and estimates of bulk permeability from geologic units. Data necessary for calibration includes snow cover, reservoir volumes (from satellite data and historic, pre-reservoir elevation data) and streamflow measurements. Global datasets for precipitation, air temperature, and PET were available at very large spatial scales (50 km) through the world scale databases, finer scale WorldClim climate data, and required downscaling to fine scales for model input. Soils data were available through world scale soil maps but required parameterization on the basis of textural data to estimate soil hydrologic properties. Soil depth was interpreted from geomorphologic interpretation and maps of quaternary deposits, and geologic materials were categorized from generalized geologic maps of each country. Estimates of bedrock permeability were made on the basis of literature and data on driller’s logs and adjusted during calibration of the model to streamflow measurements where available. Results of historical water balance calculations throughout the Tigris and Euphrates River basins will be shown along with details of processing input data to provide spatial continuity and downscaling. Basic water availability analysis for recharge and runoff is readily available from a determinisitic solar radiation energy balance model and a global potential evapotranspiration model and global estimates of precipitation and air temperature. Future climate estimates can be readily applied to the same water and energy balance models to evaluate future water availability for countries around the globe.

Understanding the unique biogeochemistry of the Mediterranean Sea: Insights from a coupled phosphorus and nitrogen model

NASA Astrophysics Data System (ADS)

Powley, Helen R.; Krom, Michael D.; Van Cappellen, Philippe

2017-06-01

The Mediterranean Sea (MS) is an oligotrophic basin whose offshore water column exhibits low dissolved inorganic phosphorus (P) and nitrogen (N) concentrations, unusually high nitrate (NO3) to phosphate (PO4) ratios, and distinct biogeochemical differences between the Western Mediterranean Sea (WMS) and Eastern Mediterranean Sea (EMS). A new mass balance model of P and N cycling in the WMS is coupled to a pre-existing EMS model to understand these biogeochemical features. Estimated land-derived inputs of reactive P and N to the WMS and EMS are similar per unit surface area, but marine inputs are 4 to 5 times greater for the WMS, which helps explain the approximately 3 times higher primary productivity of the WMS. The lateral inputs of marine sourced inorganic and organic P support significant fractions of new production in the WMS and EMS, similar to subtropical gyres. The mass balance calculations imply that the MS is net heterotrophic: dissolved organic P and N entering the WMS and EMS, primarily via the Straits of Gibraltar and Sicily, are mineralized to PO4 and NO3 and subsequently exported out of the basin by the prevailing anti-estuarine circulation. The high deepwater (DW) molar NO3:PO4 ratios reflect the high reactive N:P ratio of inputs to the WMS and EMS, combined with low denitrification rates. The lower DW NO3:PO4 ratio of the WMS (21) compared to the EMS (28) reflects lower reactive N:P ratios of inputs to the WMS, including the relatively low N:P ratio of Atlantic surface water flowing into the WMS.